CA2334137A1 - Method and apparatus for concentrating a solute in solution with a solvent - Google Patents
Method and apparatus for concentrating a solute in solution with a solvent Download PDFInfo
- Publication number
- CA2334137A1 CA2334137A1 CA002334137A CA2334137A CA2334137A1 CA 2334137 A1 CA2334137 A1 CA 2334137A1 CA 002334137 A CA002334137 A CA 002334137A CA 2334137 A CA2334137 A CA 2334137A CA 2334137 A1 CA2334137 A1 CA 2334137A1
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- CA
- Canada
- Prior art keywords
- solution
- mixture
- evaporating
- dilute
- solvent
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/42—Regulation; Control
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/40—Concentrating samples
- G01N1/4022—Concentrating samples by thermal techniques; Phase changes
- G01N2001/4027—Concentrating samples by thermal techniques; Phase changes evaporation leaving a concentrated sample
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N35/00—Automatic analysis not limited to methods or materials provided for in any single one of groups G01N1/00 - G01N33/00; Handling materials therefor
- G01N35/10—Devices for transferring samples or any liquids to, in, or from, the analysis apparatus, e.g. suction devices, injection devices
- G01N2035/1027—General features of the devices
- G01N2035/1034—Transferring microquantities of liquid
- G01N2035/1037—Using surface tension, e.g. pins or wires
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S159/00—Concentrating evaporators
- Y10S159/12—Radioactive
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S159/00—Concentrating evaporators
- Y10S159/19—Acid
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S159/00—Concentrating evaporators
- Y10S159/20—Additive
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S159/00—Concentrating evaporators
- Y10S159/37—Ported
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S203/00—Distillation: processes, separatory
- Y10S203/11—Batch distillation
Abstract
A method and an apparatus for forming a prescribed concentration of a substance in a mixture with a fluid from a dilute mixture which is a solutio n of a solute in a solvent, the apparatus (10) including a frame (12) carrying a vertically oriented syringe (14), a stepper motor (16), a laser micrometer (18), a heater (38) for heating and evaporating a drop of the solution suspended from the syringe to concentrate the solution, and further for heating the concentrated solution after it has been loaded into a source, evaporating the solvent and plating the solute onto the surface, and a contr ol system.
Description
METHOD AND APPARATUS rOR CONCENTRtITING A
SOLUTE IN SOLUT10N ~VITII A SOI~VI:NT
I3ACICGROUND Or TIIIJ INVENTION
This invention relates generally to the production of concentrated solutions, and, more particularly, to a method and an apparahrs for forming a concentrated solution, of a prescribed concentration of solute in a solvent, frorn a comparatively dilute solution.
Innumerable chemical applications require concentrated solutions of a solute dissolved in a solvent. IJach application has unique requirements for the tye of solute, the type of solvent, and the concentration of tire solute in the solvent. Such solutions, however, are generally available only in a limited number of concentrations from traditional suppliers. The ability to vary a solution's concentration is therefore an important art for a wide variety of applications.
The concentration of a solution can be increases! through the addition of more solute, or the evaporation of solvent from the solution. In the case of some solutions, such as radioactive solutions, additional solute is often not readily available, and thus the addition of more solute is,not practicable. These solutions require evaporative concentration methods.
In conventional evaporative concentration methods, tire solution is located in a container, such as a beaker. The solvent is then evaporated, preferably with the addition of heat, and the level of solution in the container tlurs goes down to an appropriate level for a smaller volume of solution. As the solution evaporates, solute precipitates out onto the container walls above the reduced level of the solution, leaving; a crust of dry precipitate where the solution level receded. This Precipitation removes solute from the solution, limiting; both the efficiency and tire accuracy of concentration. These problems are exacerbated when dealing with hazardous and/or costly solutions, such as solutions containing; radioactive solutes, in that the quantity of precipitated solute is unknown, and it is difficult to efficiently recover tire solute in a practical form. .
Accordingly, there has existed a definite need for a method, and related apparatus, to concentrate a solute in solution with a solvent without significant precipitation of the solvent. The present invention fulfills this need and provides further related advantages.
SUMMARY Or TIIC INVh.N'TION
The present invention provides a method, and an apparatus, for forming a prescribed concentration of a substance in a mixture with a fluid, from a comparatively dilute mixhrre. The mixture is most preferably a solution of a solute in a solvent. The following summary and description generally discuss the invention in terms of a particularly preferred solution and a preferred use for that solution;
however, in its broadest embodiments, the invention encompasses both the use for other solutions, and the use for a suspension of a solid substance in a fluid to form a mixUrre (which can also be refewed to as a slurry). The invention provides for significant economic, safety and quality benefits over conventional evaporative systems.
The apparatus of the invention features a syringe configured to pass the dilute solution through an orifice to form a suspended globule (such as a droplet) of the dilute solution from which solvent is evaporated. The apparatus is configured such that the suspended globule is in contact with sufficiently little solid material to avoid significant precipitation and plating of solute as the solvent evaporates.
Preferably, tire solution becomes suspended as a drop hanging by surface tension forces from a flat, horizontal, contact surface surrounding the orifice. The orifice adjoins a narrow passageway that is configured to substantially prevent concentration gradient diffusion from the evaporating dilute solution as it becomes concentrated. 'fire apparatus of tire invention preferably also feahrres a measuring device; such as a laser rnicrometer, configured to gauge the amount of suspended solution, as well as a heater configured to provide a stream of heated gas to the suspended solution to accelerate the evaporation of solvent from the solution.
The inventive method and apparahrs provide significant advantages over known methods and apparahrs, such as the known method of simply evaporating solvent from a solution contained in a container. Por the inventive method and apparatus, the suspended solution has little contact with a solid contact surface, thus minimizing the solid surface on which plating can occur. Purtlrennore, the area of contact is substantially constant, and tlnrs remains wet. Tlris advantage is particularly beneficial when the relevant solution is difficult to handle, such as is the case for radioactive solutions.
The invention also features monitoring the size of the suspended solution, and further feahrres passing additional dilute solution from the orifice to maintain the size of the drop between a prescribed minimum size and a prescribed rnaximurn size, during evaporation of the solvent. The monitoring and emission continue until the drop has reached the prescribed concentration. These feahrres advantageously provide for the concentration of substantially larger quantities of solution to substantially higher concentration levels within the natural limitations on drop size (i.e., the limitations on the amount of weight that the surface tension forces can support). These features also provide for little to no precipitation losses of solute during evaporation of the solvent.
Additionally, the invention feattrres a computerized control system that, in combination with the syringe, the measuring device and the beater, advantageously provides for tire production of extremely accurate quantities of solution that are concentrated to very specific concentrations.
Other features and advantages of the invention will become apparent from llre following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.
IiRIIJF DTSCRIPTION Or 'f III: DRA1VINGS
1~IG. IA is a perspective view of an apparatus for concentrating an amount of solute in solution, embodying features of the present invention.
F'IG. IB is a front elevational view of the apparatus depicted in 1~IG. IA.
1~1G. IC is a left side elevational view of the apparahrs depicted in I:IG.
lA.
1~IG. 2A is a front elevational view of tfre apparatus depicted in PIG. lA, with a laser micrometer and a pick-off device not depicted to better depict the devices behind the laser micrometer and pick-off device.
hIG. 2B is a side elevational view of the apparahrs depicted in I;IG. 2A.
I~IG. 3A is an elevational view of a syringe used in the ahparams cl~picte~l in hlG. 1 A.
1~IG. 3I3 is a Partial, cross-sectional, elevational view of a cuicl-portion of the syringe depicted in rIG. 3A.
(~IG. 3C is a partial, cross-sectional, elevatiorcal view of a lower tij~ of Ilce syringe: depicted in rIG. 3A.
I~1G. 4A is a cross-sectional elevational view of a beater used in tl~e al~pnratus clel~icle~i in rIG. lA, taken along line 4-~I of IUG. 2A.
I~IG. X113 is a plan view of the Neater delicte:d is TIG. ~1A.
IvIG. ~1C is a side elevatioccal view of the Iceater depicted in lIG. ~tA.
I~IG. 5A is a front elevational view of flee alyaratus del~ictecl in I~I(.~.
lA, with n final-evaporation port of a beater directly I~elow a source, and with a laser micrometer not depicted to Fetter depict Ilce devices Fclcind the laser ruicrorneter.
1~1G. 513 is ~ side elevational view of the all~aratus depicted in I~IG. SA.
I~IG. fiA is ~ front elevational view of the apparatus clelicted iu l~ ICi.
2A, with n rrst vial entirely Felow a needle.
f~IG. CI3 is a front elevational view of flee apparatus depicted is I~IC~.
f>A, witU
tlce ueeclle extending fully into flee f first viU.
hIG. 6C is a front elevational view of tire apparatus depicted in f IG. GA, wit! a concentration port of a heater directly below the needle.
FIG. 6D is a front elevational view of the apparatus depicted in FIG. 6A, with a second vial entirely below the needle.
FIG. 6E is a front elevational view of the apparatus depicted in F1G. 6A, with the needle extending fully into the second vial.
DLTAILTD DIJSCRIPTION Oh' TIIr PRrrIJtZRIaD r111130D11111?NTS
An apparahrs 10 for forming a concentrated solution, from a comparatively dilute solution, according to the present invention, is shown in FIGS. lA - 1C. The apparatus is usefirl in concentrating a solution to a prescribed concentration level from a comparatively dilute concentration level. Tlie apparatus is particularly useful for concentrating a solute that is costly, irazarclous, and/or particularly susceptible to precipitating and plating onto a solid surface, to a prescribed concentration of solute in a solvent, and most particularly to concentrations in a solvent that entail the evaporation of a comparatively large portion of the solution.
One such solution is radioactive orlhoplrosplroric acid in a water solvent.
The apparahrs is firrther usefirl for providing the concentrated solution in a suspended drop that can be used to form a substantially uniform plated coating of solute within a source, which is preferably a tubular device for receiving the solute. Tlre resulting source, being coated with the radioactive solute, provides a useful radiation source for intravascular radiotherapy in the prevention of restinosis following percutaneous transluminal angioplasly, as described in U.S. Patent No. 5,199,939, wliiclr is incorporated herein by reference. A preferred source for use in the rIlVeIrtloll Is described in the concurrently filed and commonly assigned application for U.S.
patent, entitled RADIATION SOURCC, having application Serial No. , wllicil is incorporated herein by reference.
The apparahrs 10 includes a frame 12 canying a vertically oriented syringe 14, a stepper motor 16, a laser micrometer 18, a high-resolution camera 20, a pick-off device 22, and a table 24. A manual syringe-adjuster 26 is configured to vertically adjust the position of the syringe with respect to the frame. The stepper motor connects to both the frame and the syringe, being conflgurec! to actuate the syringe to form a drop-sized duantity of solution, the size of which can be measured by the laser micrometer. Preferably the laser micrometer is configured to measure the drop at an angle to better adapt to the changing configuration of tile drop at different sizes.
A Model 50300 pump, available from the Kloelln Company, Inc., of Las Vegas, Nevada, provides a suitable stepper motor configured to be used with a syringe, where the stepper motor is controllable by a computer through an RS-232 interface.
An LS-3100 Series Laser Scan Micrometer, available from the Keyence Corporation of America, of Saddle Brook New Jersey, provides a suitable laser micrometer, and is capable of doing 400 scans per second at,a measurement precision of i2lun.
Verrical, in the context of this embodiment, generally refers to a gravity-based reference frame defining the direction of forces necessary to suspend a drop of the solution from the syringe. However, for an appropriate embodiment it can be considered eduivalent to reference frames relevant to defining the forces necessary to suspend the solution. ror example, a drop hanging from a spinning embodiment will exhibit "centrifugal force" effects, and tiers will have a partially momentum-based reference frame.
As seen in PIGS. 2A - 2B, which depict tire apparatus of 1' IGS. 1 A - 1 C
with the laser micrometer 18 and tire pick-off device 22 removed, a first motor 28 is configured to laterally adjust the position of the table 24 with respect to the frame by way of a first screw drive 30 (see FIG. lA). The table carries a platter 32, whicfr is vertically adjusted with respect to the table by a second motor 34, in cooperation with a second screw drive 36. The table also carries a beater 38 configured to Treat and evaporate a drop of solution suspended from the syringe 14 to concentrate the solution, and further configured ~.o Treat the concentrated solution after it lras been loaded into a source, evaporating the solvent and plating the solute onto tire source.
The apparatus firrtlrer includes a computerized control system (not shown) configured to control the first motor 28, the second motor 3~, the stepper motor 16 and the heater 38. The control system can he firr-ther configured to control all other controllable aspects of the apparatus, such as tire syringe-adjuster 26, anti any related production devices.
As seen in FIGS. 3A - 3C, tire syringe 14 includes a vertically oriented body 50, a vertically oriented needle 52, a vertically oriented plunger 54, and a mounting lnrb 56 configured to mount the syringe's body and needle to tire frame 12.
The syringe body is configured in the standard form of a syringe, having a cylindrical chamber 58 with a consistent cross section extending down to a bottom end, where tire chamber rounds down to a small opening 60. The syringe body is preferably transparent, having striations (not shown) indicating the VOltrrrle Of the Cllalllber from the point of the striation down to the small opening. The striations serve to allow an operator of the system to visually verify tire proper functioning of tire syringe.
The plunger S~1 includes a shaft 62 drat can to clriverr into and otrt of the syrinl;e body's chlmher S8 by the stepper motor 16. A head 6Il is aftixecl to a hottorn end of the shaft, and is situated within the clraml>er. 'flre head conforms to the cross section of the chamber, forming art airtiglrt seal between the bead arrd t1m chamber as the bead slides up alld down tire chamber, motivated by the shaft. '1'Ite plmyer, driven by the stepper motor, tltrts acts as a piston, capa(rle of drawinb a fluid tlrrorrglr the srnall opeuitrg 60 arui into the chamber, and driving a Cltri<I tlrroublr tire small openirtb and orrt of the chamber, by moving up and down with respect to the clranth~r.
At any given position within tire ciraruher SF, tire lrlrrttger bead 6_I
therefore forms an enclosed cavity witlritr tire cltmuber, the cavity lreitrg open only, tltrouglr the small opening 60. Advancinb tire player into tire clratuber r~clnces the cavity's volume, driving tire contents of tire cavity out tltroublr tile sruall openiul;.
Wltert the plunger is fully advanced clown into tire cltanrlrer, the cavity's volrrtne is lowered to essentially zero, anc! tire cavity is emlrtied of srrl>starttially all fluid or gas tlrrouglt tire small opening. A fully advanced plrrnber, therefore, el~lectively c:vactrates Ilte syringe. Retracting the lrlunger from tire clr,ma(~er increases the voltrtrre of tlrc cavity, slurs drawing fluid or gas into tire cavit~~.
'1'lte mounting lutb S6 is a block-like slructurc, an Itpper chef of wlriclr conforrrtirtgly receives tire lower end of the syrinl;e body S0, lroldinl; the syritrt;e Uoci~, rigidly in place relative to Ilte frame. An it(111esrVe StICII 1S ~I)0?~)' is used to frond the syrittgc body to Ilte mounting ftub. 'flte mourrtinb loth defines a hollow sprats 66 providing a corridor for tire needle 52 to extend clown froth tile Cllilllll)er'S Stlritll opening 60.
'fire needle S2 Iris bout an outer shell 6F, and a concentric, hollow inner trrpre 7U extending tltroublr the older shell. An upper earl of tire irtrrer l W is alTixed tc~
the syringe body, such as by epoxy. It is affixed to tire small opening of tire syringe body, providing a vertical passage 72 in communication with tire chamber through the small opening. The inner tube extends down from the small opening 60 to a lower tip 74 of the needle. The passage has a generally constant cross sectional area, which necks down to form an orifice at the lower tip of the needle. The orifice preferably ranges from .005 in. to .010 in. in diameter.
Tire needle's outer shell 68 extends from tire lower tip 74 of the needle 52, up to a lower end of the mounting lmb 56. The outer shell has a generally consistent cross section that necks down at its lower end to merge with tire inner tube's lower end, forming the lower tip of the needle. Tire needle's outer shell is affixed to the lower end of the mounting hub, such as with epoxy, providing sh-rrctural support to the needle and holding the needle rigidly in place relative to tire frarne 12 and the syringe body 50.
The needle's lower tip 74 provides a contact surface 76 that is preferably not convex, and that is most preferably substantially flat and horizontal, the contact surface including both the lower end of the inner tutee 70 and the lower end of the outer shell 68. This horizontal contact surface is srnootlr, providing a substantial area to support a drop at tire lower tip of the needle 52. Tlurs, tire syringe 1~l for-rns a container, having an orifice at the needles lower tip, and being configured to pass fluids from within the container out through the orifice.
Preferably, the contact surface has a diameter ranging between .030 in.
and .090 in. As the size of the contact surface increases, the stability of a drop suspended from the contact surface increases. I-Iowever, the final concentrated size of a drop banging from the contact surface can be reduced from its original size, and thus, after concentration, a larger contact surface may cause the drop to be difficult to see.
rurihennore, a larger contact surface can lead to surface tension forces that make it diffrcult to remove the drop from the contact surface.
While the above-described components of the syringe l~t are preferred, a wide variety of components fall within the definition of, or are equivalent to, a syringe.
In particular, a syringe as claimed could be embodied in any device drat can controllably pass a substance from a chamber out of an orifice, where tire emission of the substance is controllable. Likewise, for syringes having a body, a needle, and a plunger, a wide variety of configurations are within the scope of the invention. Por example, a horizontally oriented body, a plunger and a needle, that can provide the same essential fimctions of the vertical syringe, fall within the scope of tire invention.
Components that are to come into contact with the solution, and particularly with the solution after it has been concentrated, are~preferably made of materials compatible with the solution. Tlrus, the needle 52 and tire body 50 are preferably made from duartz.
Returning to rlGS. lA and 2A - 2I3, the table 24 is confil;ured to be laterally positionable vertically below the needle 52. Tlre first motor 28 can laterally adjust the table's position, by use of the screw drive 30, so as to place either tire heater 38 or the platter 32 directly below the needle. The platter is configured to carry a plurality of vessels, such as vials, each of which can be laterally positioned directly under the needle by the first motor. A first vial 80 of the plurality of vessels contains a fluid for flushing the syringe 14, such as tire solvent, water. A second vial 82 of tire plurality of vessels contains a dilute solute in solvent, such as dilute radioactive orthophosphoric acid in water.
Preferably, tire viols 80, 82 are received in spring-loaded Ir,rys ti.l irr the platter 32. Tlre spring-loaded bays provide protection against the needle 52 breakine if it strikes the bottom of one of tire vials.
Tlre lreater 3S, wlriclr is configured to beat a drop of llrrid suspended fronn tire lower- tip 7~1 of tire needle 52, can Ire of a wide variety of clesi~ns. 1'referalrly tire beater is configured to beat and evaporate tire drop by creatinb a column of heated bas (lowinb up arrd around tire drop. 'fire gas can be air or any other srrbslance drat would allow and encoura6e the evaporation of the solvent. 1'refera(ly the bas is an inert has such as nitrogen. 1'lre gas is treated to a soft icient level to encourage the evaporation of the solvent.
lvor example, tire beater can be a verlic~ll~~ oriented coil of a resistor wire, wlriclr can be heated by the application of a voltabe across tlrc wire.
Srrclr a Beater beats tire air in the vicinity of the wire, wlriclr urea rises tlrrorrglr tire cooler surrounding air to form a column of heated air.
A preferred heater, as seen in 1~IG~. ~IA - ~1C, inclrrcles tr tatty OU and a valve: O2. t1n inlet 9~1 on tire body is configured to receive exparulinl;
l;as, lrref~raUly being nitro6en, from a pressurized supply (not shown). Gas received by the inlet expands tlrrouglr a tubular main passage 96, wlriclr is partially surrounded by a beater element 98, preferably being a nicbrorne wire spiraled alonb the outside of tire hod~~, the wire hein~ encased in a Biglr-temperature epoxy. Passing tlworrl;lr tlrrr main passage, ilre gas is directed by tyre valve tlrrouglr one of two Irons, Ireirrg a concentration port 100 anti a final-evaporation port 102.
'flre valve 92 includes a tubular portion 10=I, tlrc exterior oC wlriclr conlorms to the interior of the heater body's maim ~assa8e 9G so as to receive tire gas into the valve. Two holes 106 in the valve's tubular portron are configured to allow il~e gas to pass through only one port 100, 102 at a time, which can be selected by rotatiorrally positioning the valve to align one hole with the selected port.
Tlie valve can be manually operated, or can be configured to be controlled by the computerized control system.
The concentration port 100 is a round vertical tube conFgured to form a column of air having an approximately round cross section when the beater 38 is activated. Tlre final-evaporation port 102 is configured to form a column of air having a band-shaped cross-section, having a larger clirnension and a smaller dimension. The final-evaporation port includes a diffusion screen 108 to produce a column of heated air having a more even distribution of heat over its cross-section.
As seen in rIGS. lA - 1C, as well as rIGS SA - 513, the pick-off device 22 is configured to retain a source 110, being a preferably tubular appliance configured to receive the drop of concentrated solution after the process of concentrating the solution on the syringe is complete. The pick-off device is further configured to position and move the retained source, while moving into contact with the drop to receive the drop from the syringe. ror proper positioning, the pick-off device includes a top adjustment screw 112, a side adjustment screw 114, and a front adjustment screw 116. ror use with radioactive solutions, these screws can include long shafts so that they can be used from outside of a radiation shield (not shovm) around the apparatus 10.
1'he source I 10, which can take numerous forms, preferably takes the for-rn of a thin hollow tube perforated with a plurality of holes, the tine being configured to draw a drop of fluid into the hrbe with capillary forces.
Preferably, the source is sized to precisely contain one drop of solution.
The high-resolution camera 20 is equipped with a zoom lens 118, and is configured to image a drop of fluid being suspended from the needle's lower tip 74.
The image can be displayed on a monitor (not shown) for an operator of the apparatus 10. The camera's configuration can also image the source 110.
Under the power of tire second motor 34, tire platter 32 is configured to vertically move the plurality vials with respect to the syrinl;e 14. Using the second screw drive 36, tire platter can be raised by the second motor such drat tire needle 52 extends fully into a vial that is located directly below tire needle, as can be seen in fIG.
6B. Likewise, the platter can be lowered such that a vial directly tinder the needle is entirely below the lower tip 74 o~'the needle, as seen in PIG. 6A, allowing tire vials to pass laterally below the needle without contacting the needle. It is preferable that the platter is configvrred to lower to a level that is convenient for posrtronrng and removing vials without sil;nificant risk of the vials hitting the needle, such as tire level depicted in rIG. 2A.
As seers in I:IGS. lA - 1C and 2A - 2B, a rnetlrod embodying tire present invention for concenri~atinl; the amount of a solute in solution with a solvent to a prescribed concentration begins by setting up tire above described apparatus and adjusting it for use. In parUicular, tire syringe-adjuster 26 is actuated to vertically adjust tire position of the syringe such that the lower tip 74 of the needle 52 resides slightly above the measurement zone of the laser micrometer 18, tlnrs configuring the laser micrometer to measure the size of a drop of solution suspended from the needle while the drop is still hanging from the needle. The stepper motor 16 firll~~
advances tire plunger 54 into the syringe body 50 to minimize the clamber size and effectively evacuate the syringe.
WO 99/62607 PG"T/US99/12554 Additionally, the heater valve 92 is adjusted to direct flue lrentui bas tlrroubir tire concentration port 100. 'fire source l 10 IS rnounted arul retainer! in tire pick-off device 22 (as seen in rIG. SI3), which is adjusted by its adjustment screws to hold tire source in close proximity to tire needle for fast and convenient use alter the solution has peen concentrarted ty the syrinbe l~t. 'l'lris position, however, must lie selected to not interfere with the operation of the apparatus' components, such as the laser micrometer 18. Two vials are positioned on the platter 32. '1'lve first vial 80 contains a solvent, such as water, to he used for flushing the syrirrbe.
'1'lie second vial 82 contains a dilute solution of a solute in a solvent, hreferalrly lrciab tire same solvent as is contained in solution in the f first vial.
With the apparatus 10 set uh and adjusted, it is olUion,rlly (and preferably) flushed and tested prior to evaporatively concentrating the solution. 'fire plrurger S4 is withdrawn from lire syringe body SO Iry the stelrlrer motor 1 C
to cause a predeter-ruine<l amount of air to tie drawn into the cavity of the clraW rer St;. 'fire table 2~1, with Ilre platter 32 adjusted such drat tire vials 80, F2 are low enough to pass laterally below tire needle S2, is laterally adjusted to place tire first vial FO directly below Ilre needle, as seen in PIG. 6A. hIGS. 6A - fit-: do not clelrict tlic laser micrometer and a pick-off device to better illustrate the positions of the umlerl~~inl;
harts of tire apparatus 10.
'fhe first viol 80 is vertically adjusted such drat tlri: needle S? extends into thi; first vial, and into lire solvent tlrerein, as seem in 1-~IG. fil3.
'I'Ire steplrer motor IC firrther witlolra~,vs tire plunger S4 from tire syringe body S0 by a calculated amount, making the clramher S8 larger, and tlurs drawing a predeterruined duantity ol' the solvent from the first vial into the syringe ciramher. Tire platter 32 is then lowered Io a position low enough to allow tire vials to hiss under the needle.
I'rel~raUly, tire platter is lowered to its lowest position, where it cannot interfere with Ilrc operation c~( tS
the laser micrometer 18 or the view of tire camera 20. The table 24 is then moved longihrdinally such that the concentration port 100 of the heater 38 is directly below the needle, as seen in rIG. 6C.
The solvent in the syringe chamber 58 is then evaporated dowry to the volume of a drop, using the same evaporation method as is described in more detail below for evaporatively concentrating the solution in the second vial 82. Tire solvent is passed out of the needle to form a drop suspended from tire needle; the drop size is measured; some of the solvent is evaporated; and the volume of tire drop is replenished to maintain the drop's size. When the solvent in tire syringe chamber is preferably reduced to a single drop, the table is moved longitudinally and vertically to a position such that the plunger can be advanced fully into the clrarnber to eject the remaining;
drop of solvent back into the first vial, such as tire position depicted in PIG. 6A.
After the apparatus 10 is set up and adjusted, and after it is optionally flushed and tested, a procedure similar to the flush and test procedure is used to evaporatively concentrate the solution in tire second vial 82. T'he plunger 54, which is fully advanced into the syringe body S0, is withdrawn from tire syringe body by the stepper motor 16 to cause a predetermined amount of air to lie drawn into the cavity.
Nahrrally, in tire parlance of this application, air can be any environment deemed preferable to conduct the procedure. The table 24, with the platter 32 adjusted such that the vials 80, 82 are low enough to pass laterally below the needle 52, is laterally adjusted to place dye second vial directly below the needle, as seen in rIG.
6I7.
The second vial 82 is vertically adjusted such that tire needle 52 extends into the dilute solution in the second vial to a depth adequate to draw a predetermined quantity of solution from tire vial, as seen in T'IG. 6C. The stepper motor 16 further withdraws the plunger 54 from the syringe body 50 by an amount selected to draw tire predetermined amount of the solution up through tire needle's hollow inner tale 70 and into the cavity. Preferably, the air previously drawn into the chamber separates the solution from the plunger's head 64, minimizing potential chemical degradation of either the plunger's bead or the solution by contact with each other.
The platter 32 is then lowered to a position low enough to allow the vials 80, 82 to pass under the needle 52 without coming into contact with the needle, or any drop of solution drat might be hanging from tire needle. If a drop is visibly hanging from the needle, the stepper motor tnay further withdraw the plunger from the syrirrge to draw the drop into the needle. Preferably, tire platter is lowered to its lowest position, where it cannot interfere with the laser micrometer I 8 or block the view of the camera 20 during evaporation. The table 24 is then moved longitudinally such drat the concentration port 100 of the heater 38 is directly below tire needle 52 to provide for evaporation of the solvent in the solution, as is seen in rIG. 6C.
Once the heater's concentration port 100 is positioned below tire needle 52, the laser micrometer takes an initial measurement of the diameter of any drop (ranging from the contact surface 78 at the lower tip 74 of tire needle.
The measurement of the drop is relayed to the computerized control system, which preferably controls the stepper motor to draw tire drop up into tire needle.
The heater is then preferably used to dry the exterior of the needle to prevent solution from later being hulled up the needle by surface tension forces.
Under the control of tire computerized control system, tire stepper motor 16 then causes the syringe 14 to produce a drop. Tlre laser micrometer 18 measures tire drop and compares the measurement with prescribed limits, being a prescribed minimum size and a prescribed maximum size. The Prescribed maximum size is selected such that surface tension forces will. reliably suspend the drop li~om tile contact surface 78 at the lower tip of the needle.
The prescribed minimum size is selected to be lame enough such that tile suspended solution is in contact with sufficiently little solid material (i.e., on the contact surface) to avoid significant precipitation and plating of solute as the solvent evaporates. It is also selected to be large enough to provide an acceptably fast evaporation rate. The prescribed minimum size is selected to be small enou6ll such that its difference from the maximum size is adeduate to accommodate tile tolerance of the stepper motor 16 (i.e., its ability to cause the emission of enough dilute solution to exceed the prescribed minimum size, but not to exceed the prescribed maximum size).
Preferably, there is little or no change in the amoluU of contact area behveen the drop and the contact surface so long as the drop is between tile Il1lI11lrlllln aIld maximum sizes, and thus the contact surface remains wet.
Under control of the control system, the stepper motor 16 advances the plunger to pass dilute solution out of the needle to the formed or forming drop, or retracts the plunger to draw solution from the drop into the needle, to adjust the size of the drop such that its measurement is greater than the prescribed rninimum measurement and less than the prescribed maximum measurement. As before, the solution is passed out of the needle or drawn into the needle by moving tile plunger 54 further into, or out of, the syringe body 50, respectively.
With tire drop adjusted to be within the prescribed limits, the heater 38 is activated to create a column of heated gas flowing over the drop llanglng from the needle 52. In particular, with reference to I:IGS. 4A - 4C, pressurized nitrogen gas is released from its supply (not shown), through the heater's inlet 94, throu6ll tile main passage 96 and out through the concentration port 100. The heater element 98 is energized, which in turn heats tire nitrogen gas as it passes through the main passage.
The heater is configured to create a column of heated gas sufficient to cause evaporation of solvent from within the drop. While the above-described beater is the prefewed embodiment of the heater, any device configured to accelerate the rate of the solvent's evaporation, whether through temperature, barometric pressure, or other relevant factors, is within the scope of the invention. While it is preferable that tire heater is energized when the drop is within tire prescribed limits, it is well within the scope of the invention to energize the heater prior to passing any solution out of the needle.
The column of heated gas evaporates some of tire solvent within the drop, causing the volume of the drop to be reduced and the size of the drop to shrink.
While the solvent within the drop is evaporating, the laser micrometer monitors the drop by continuing to measure the size of the drop. The measurements are relayed to the control system, which compares the measurements with tire prescribed limits.
Returning to rIGS. IA - 1C and 2A - ZI3, when tire size of tire drop falls below the prescribed minimum, the control system instincts the stepper motor 1G to advance the plunger 54 into the syringe body 50, increasing tire size of the drop to a size larger than tire prescribed minimum. Preferably, tire plunger is not advanced far enough to make the drop larger than the prescribed rrlaXllllilllr Slze, as it is not preferable to draw concentrated solution back into the needle 52.
Preferably, the needle is configured to he nawow enough near tire orifice to substantially prevent the concentrated solution fr'OIrl diffusing rrp tire needle durinf;
tire evaporation. hurtherntore, the stepper motor and heater are preferably configured, and the prescribed minimum and maximum sizes are preferably chosen, to provide for evaporation and addition of solution to occur at a rate allowing near-continuous a<lclition, so as to substantially prevent concentration gradient diffusion from tire evaporating mixture as it becornes more concentrated.
The size of the drop is continuously monitored and adjusted until enoug;lr solvent has been evaporated to cause the drop to reach a prescribed concentration of solute in solution with tire remaining; solvent, or until all of the dilute solution in tire syringe passes out into the drop. Depending; on tire desired concentration, it might be necessary to frlrther concentrate the drop, reducing its size below tile prescribed minimum. As the drop reaches the desired concentration, the greater is turned off, so as to stop or limit any filrther evaporation.
Little or no precipitation occurs on the contact surface 78 so long as tire drop is maintained between tire minimum and IrIaXIIrlrrrrl SIZeS. Preferably, tile contact surface is shaped, sized and oriented such that the contact area between it and the drop changes little (or not at ail) if the drop is to be shrunk below the minimum size. ror such a contact surface, little or no precipitation occurs on the contact surface even when tire drop is reduced below the minimum size.
The resulting drop of concentrated solution may then be removed from the needle 52. 1n tlris embodiment, tire concentrated solution is used to form a substantially uniform coating of solute plated within the source 110.
Preferably, tire drop of concentrated solution is removed from the needle by touclring the bottom ed6e of tire drop with the center of the source. Upon touching the source, the drop is drawn into the source through its perforations by capillary action, pulling the drop off of the needle.
The position of the source is adjusted to touch tire drop throul;ll tire use of the pick-off device's top adjustment screw I 12, side adjustment screw 1 l~l, and front adjustment screw 116. While the above describes the preferred embodiment, a variet~~
of pick off techniques are envisioned as within the scope of the invention.
Por example, an open end of the source can be touched to the side of the drop, drawing the drop into the end of the source by capillary forces.
As seen in FIGS. SA - SI3, tire concentrated solution within the source 110 is then heated to evaporate the solvent, precipitating the solute and causing it to plate onto the source, forming a layer of solute in the interior of the source. To do so, the table is first laterally adjusted to position the heater's final-evaporation port 102 under the source. The heater valve 92 is then actuated to align the concentration-port valve's hale (see 106 in FIG. 4A) with the final-evaporation ,port. Tlre nitrogen gas is again passed through the heater with the heater element energized, causing a band-shaped, diffused column of heated air, which approximates the shape of the source, to rise up to the source and evaporate the last of tl~e solvent.
lxample An number of experimental nrns have been ruade in the ambient conditions comprising an air temperature of 90-95 ° C. Tlte syringe was configured with a needle having a .OIO in. bore, which reduced to .005 in. at tire lower tip (i.e., at the orifice). The needle also had a .090 in. outer diameter, which reduced to .070 in. at the lower tip.
A dilute solution of radioactive ortltophosphoric acid in water, exhibiting approximately 1.5 - 2.0 mCi/mm3 was used as the starting material. After the syringe was set up and adjusted, and was flushed and tested with water, 225 mnt' of the dilute solution were drawn up into the syringe. The size of the suspended drop, which was estimated to have adequate surface tension forces to support a drop size up to ~1 mrn, WO 99/b2607 PCT/US99/12554 was approximately maintained in the vicinity of 2.~1 mm (1 .2) mm for sal~~t~~. llho«
heating, evaporation typically occurred at rates of S a«n'/miu. At this rate, flue (1«id velocity through tire orifice averaged 395 mm/rui«., effectively peeve«tillg diffusion hack lllrougli the orifice. Tlle volume of tile concentrated drop vws in tll~
vie;iait~~ of .t~
men', which exhibited 200 - 350 mCi, an<I preferably 300 mCi.
'flee above-described metltocl and ahparat«s embody a broad array of novel li:atlrres of the invention. However, these features :Ira not limited is scone Ily the descrilaed embodiments, as n«mero«s other embodiments are willtin Ille scope of the invention. To demonstrate the breadth of the i«ventioll, a «lllnller of embodiment variations are discussed below.
'flee described embodiments characterize tile solution as sllshe«decl in air.
However the invention is equally applicable to any cnvironnlent, gascolls clr otherwise, tlral allows tile solution to be s«spe«ded witflirl it, ,nut that can accolnnmlalo tile removal of the sot«tio«'s solvent, s«clr as by evaporation.
l~nrtlyermore, the removal of the sot«tioll's solve) does not necessarily )lave to be accelerated by the addition of heat. Other euvironllle«tal cllaracteristics, s«clt as pressure, may instead he varied to improve tile evaporation rate.
lncle~el, tile solvent could he allowed to evaporate without any stirnlllation, altllollgll it could ~re1lly len~tllen the necessary tithe for many emlaodirnents.
'lvvo aspects of the invention have been described as simullaneoltsl~- used to minimize the precipitatio« of solute d«rin~ evaporation. 'l'lle first aspect is tlm suspension of tile solution such that it is in contact with little sllrlilce area of a contact surface, Irrovidin~ for little or no change in the contact s«rface area.
'I'lle second aspect is tile adclilion of dilute s~IWion to the glollule of sollltiorl (O
Illallllillll the vt>Illlll(' of combined SOlI1I10r1 Wltllllr 1 bound, providing for little or no cllauge in the contact surface area. >;ach of these aspects may lie used individually within the scup of the invention.
rrom the foregoing description, it will be appreciated that the present invention provides a method and apparatus to concentrate a solute in solution with a solvent, without the inefficiencies and problems associated with conventional evaporative systems. While particular fornis of the invention leave been illustrated and described, it will be apparent that various other modifications can be made without departing from the spirit and scope of the invention. Thus, although tile invention has been described in detail with reference only to the preferred ernbodunents, those having ordinary skill in the art will appreciate that various modifications can be made without departing from the invention. Accordingly, the invention is not intended to lie limited, and is defined with reference to the following claims.
SOLUTE IN SOLUT10N ~VITII A SOI~VI:NT
I3ACICGROUND Or TIIIJ INVENTION
This invention relates generally to the production of concentrated solutions, and, more particularly, to a method and an apparahrs for forming a concentrated solution, of a prescribed concentration of solute in a solvent, frorn a comparatively dilute solution.
Innumerable chemical applications require concentrated solutions of a solute dissolved in a solvent. IJach application has unique requirements for the tye of solute, the type of solvent, and the concentration of tire solute in the solvent. Such solutions, however, are generally available only in a limited number of concentrations from traditional suppliers. The ability to vary a solution's concentration is therefore an important art for a wide variety of applications.
The concentration of a solution can be increases! through the addition of more solute, or the evaporation of solvent from the solution. In the case of some solutions, such as radioactive solutions, additional solute is often not readily available, and thus the addition of more solute is,not practicable. These solutions require evaporative concentration methods.
In conventional evaporative concentration methods, tire solution is located in a container, such as a beaker. The solvent is then evaporated, preferably with the addition of heat, and the level of solution in the container tlurs goes down to an appropriate level for a smaller volume of solution. As the solution evaporates, solute precipitates out onto the container walls above the reduced level of the solution, leaving; a crust of dry precipitate where the solution level receded. This Precipitation removes solute from the solution, limiting; both the efficiency and tire accuracy of concentration. These problems are exacerbated when dealing with hazardous and/or costly solutions, such as solutions containing; radioactive solutes, in that the quantity of precipitated solute is unknown, and it is difficult to efficiently recover tire solute in a practical form. .
Accordingly, there has existed a definite need for a method, and related apparatus, to concentrate a solute in solution with a solvent without significant precipitation of the solvent. The present invention fulfills this need and provides further related advantages.
SUMMARY Or TIIC INVh.N'TION
The present invention provides a method, and an apparatus, for forming a prescribed concentration of a substance in a mixture with a fluid, from a comparatively dilute mixhrre. The mixture is most preferably a solution of a solute in a solvent. The following summary and description generally discuss the invention in terms of a particularly preferred solution and a preferred use for that solution;
however, in its broadest embodiments, the invention encompasses both the use for other solutions, and the use for a suspension of a solid substance in a fluid to form a mixUrre (which can also be refewed to as a slurry). The invention provides for significant economic, safety and quality benefits over conventional evaporative systems.
The apparatus of the invention features a syringe configured to pass the dilute solution through an orifice to form a suspended globule (such as a droplet) of the dilute solution from which solvent is evaporated. The apparatus is configured such that the suspended globule is in contact with sufficiently little solid material to avoid significant precipitation and plating of solute as the solvent evaporates.
Preferably, tire solution becomes suspended as a drop hanging by surface tension forces from a flat, horizontal, contact surface surrounding the orifice. The orifice adjoins a narrow passageway that is configured to substantially prevent concentration gradient diffusion from the evaporating dilute solution as it becomes concentrated. 'fire apparatus of tire invention preferably also feahrres a measuring device; such as a laser rnicrometer, configured to gauge the amount of suspended solution, as well as a heater configured to provide a stream of heated gas to the suspended solution to accelerate the evaporation of solvent from the solution.
The inventive method and apparahrs provide significant advantages over known methods and apparahrs, such as the known method of simply evaporating solvent from a solution contained in a container. Por the inventive method and apparatus, the suspended solution has little contact with a solid contact surface, thus minimizing the solid surface on which plating can occur. Purtlrennore, the area of contact is substantially constant, and tlnrs remains wet. Tlris advantage is particularly beneficial when the relevant solution is difficult to handle, such as is the case for radioactive solutions.
The invention also features monitoring the size of the suspended solution, and further feahrres passing additional dilute solution from the orifice to maintain the size of the drop between a prescribed minimum size and a prescribed rnaximurn size, during evaporation of the solvent. The monitoring and emission continue until the drop has reached the prescribed concentration. These feahrres advantageously provide for the concentration of substantially larger quantities of solution to substantially higher concentration levels within the natural limitations on drop size (i.e., the limitations on the amount of weight that the surface tension forces can support). These features also provide for little to no precipitation losses of solute during evaporation of the solvent.
Additionally, the invention feattrres a computerized control system that, in combination with the syringe, the measuring device and the beater, advantageously provides for tire production of extremely accurate quantities of solution that are concentrated to very specific concentrations.
Other features and advantages of the invention will become apparent from llre following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.
IiRIIJF DTSCRIPTION Or 'f III: DRA1VINGS
1~IG. IA is a perspective view of an apparatus for concentrating an amount of solute in solution, embodying features of the present invention.
F'IG. IB is a front elevational view of the apparatus depicted in 1~IG. IA.
1~1G. IC is a left side elevational view of the apparahrs depicted in I:IG.
lA.
1~IG. 2A is a front elevational view of tfre apparatus depicted in PIG. lA, with a laser micrometer and a pick-off device not depicted to better depict the devices behind the laser micrometer and pick-off device.
hIG. 2B is a side elevational view of the apparahrs depicted in I;IG. 2A.
I~IG. 3A is an elevational view of a syringe used in the ahparams cl~picte~l in hlG. 1 A.
1~IG. 3I3 is a Partial, cross-sectional, elevational view of a cuicl-portion of the syringe depicted in rIG. 3A.
(~IG. 3C is a partial, cross-sectional, elevatiorcal view of a lower tij~ of Ilce syringe: depicted in rIG. 3A.
I~1G. 4A is a cross-sectional elevational view of a beater used in tl~e al~pnratus clel~icle~i in rIG. lA, taken along line 4-~I of IUG. 2A.
I~IG. X113 is a plan view of the Neater delicte:d is TIG. ~1A.
IvIG. ~1C is a side elevatioccal view of the Iceater depicted in lIG. ~tA.
I~IG. 5A is a front elevational view of flee alyaratus del~ictecl in I~I(.~.
lA, with n final-evaporation port of a beater directly I~elow a source, and with a laser micrometer not depicted to Fetter depict Ilce devices Fclcind the laser ruicrorneter.
1~1G. 513 is ~ side elevational view of the all~aratus depicted in I~IG. SA.
I~IG. fiA is ~ front elevational view of the apparatus clelicted iu l~ ICi.
2A, with n rrst vial entirely Felow a needle.
f~IG. CI3 is a front elevational view of flee apparatus depicted is I~IC~.
f>A, witU
tlce ueeclle extending fully into flee f first viU.
hIG. 6C is a front elevational view of tire apparatus depicted in f IG. GA, wit! a concentration port of a heater directly below the needle.
FIG. 6D is a front elevational view of the apparatus depicted in FIG. 6A, with a second vial entirely below the needle.
FIG. 6E is a front elevational view of the apparatus depicted in F1G. 6A, with the needle extending fully into the second vial.
DLTAILTD DIJSCRIPTION Oh' TIIr PRrrIJtZRIaD r111130D11111?NTS
An apparahrs 10 for forming a concentrated solution, from a comparatively dilute solution, according to the present invention, is shown in FIGS. lA - 1C. The apparatus is usefirl in concentrating a solution to a prescribed concentration level from a comparatively dilute concentration level. Tlie apparatus is particularly useful for concentrating a solute that is costly, irazarclous, and/or particularly susceptible to precipitating and plating onto a solid surface, to a prescribed concentration of solute in a solvent, and most particularly to concentrations in a solvent that entail the evaporation of a comparatively large portion of the solution.
One such solution is radioactive orlhoplrosplroric acid in a water solvent.
The apparahrs is firrther usefirl for providing the concentrated solution in a suspended drop that can be used to form a substantially uniform plated coating of solute within a source, which is preferably a tubular device for receiving the solute. Tlre resulting source, being coated with the radioactive solute, provides a useful radiation source for intravascular radiotherapy in the prevention of restinosis following percutaneous transluminal angioplasly, as described in U.S. Patent No. 5,199,939, wliiclr is incorporated herein by reference. A preferred source for use in the rIlVeIrtloll Is described in the concurrently filed and commonly assigned application for U.S.
patent, entitled RADIATION SOURCC, having application Serial No. , wllicil is incorporated herein by reference.
The apparahrs 10 includes a frame 12 canying a vertically oriented syringe 14, a stepper motor 16, a laser micrometer 18, a high-resolution camera 20, a pick-off device 22, and a table 24. A manual syringe-adjuster 26 is configured to vertically adjust the position of the syringe with respect to the frame. The stepper motor connects to both the frame and the syringe, being conflgurec! to actuate the syringe to form a drop-sized duantity of solution, the size of which can be measured by the laser micrometer. Preferably the laser micrometer is configured to measure the drop at an angle to better adapt to the changing configuration of tile drop at different sizes.
A Model 50300 pump, available from the Kloelln Company, Inc., of Las Vegas, Nevada, provides a suitable stepper motor configured to be used with a syringe, where the stepper motor is controllable by a computer through an RS-232 interface.
An LS-3100 Series Laser Scan Micrometer, available from the Keyence Corporation of America, of Saddle Brook New Jersey, provides a suitable laser micrometer, and is capable of doing 400 scans per second at,a measurement precision of i2lun.
Verrical, in the context of this embodiment, generally refers to a gravity-based reference frame defining the direction of forces necessary to suspend a drop of the solution from the syringe. However, for an appropriate embodiment it can be considered eduivalent to reference frames relevant to defining the forces necessary to suspend the solution. ror example, a drop hanging from a spinning embodiment will exhibit "centrifugal force" effects, and tiers will have a partially momentum-based reference frame.
As seen in PIGS. 2A - 2B, which depict tire apparatus of 1' IGS. 1 A - 1 C
with the laser micrometer 18 and tire pick-off device 22 removed, a first motor 28 is configured to laterally adjust the position of the table 24 with respect to the frame by way of a first screw drive 30 (see FIG. lA). The table carries a platter 32, whicfr is vertically adjusted with respect to the table by a second motor 34, in cooperation with a second screw drive 36. The table also carries a beater 38 configured to Treat and evaporate a drop of solution suspended from the syringe 14 to concentrate the solution, and further configured ~.o Treat the concentrated solution after it lras been loaded into a source, evaporating the solvent and plating the solute onto tire source.
The apparatus firrtlrer includes a computerized control system (not shown) configured to control the first motor 28, the second motor 3~, the stepper motor 16 and the heater 38. The control system can he firr-ther configured to control all other controllable aspects of the apparatus, such as tire syringe-adjuster 26, anti any related production devices.
As seen in FIGS. 3A - 3C, tire syringe 14 includes a vertically oriented body 50, a vertically oriented needle 52, a vertically oriented plunger 54, and a mounting lnrb 56 configured to mount the syringe's body and needle to tire frame 12.
The syringe body is configured in the standard form of a syringe, having a cylindrical chamber 58 with a consistent cross section extending down to a bottom end, where tire chamber rounds down to a small opening 60. The syringe body is preferably transparent, having striations (not shown) indicating the VOltrrrle Of the Cllalllber from the point of the striation down to the small opening. The striations serve to allow an operator of the system to visually verify tire proper functioning of tire syringe.
The plunger S~1 includes a shaft 62 drat can to clriverr into and otrt of the syrinl;e body's chlmher S8 by the stepper motor 16. A head 6Il is aftixecl to a hottorn end of the shaft, and is situated within the clraml>er. 'flre head conforms to the cross section of the chamber, forming art airtiglrt seal between the bead arrd t1m chamber as the bead slides up alld down tire chamber, motivated by the shaft. '1'Ite plmyer, driven by the stepper motor, tltrts acts as a piston, capa(rle of drawinb a fluid tlrrorrglr the srnall opeuitrg 60 arui into the chamber, and driving a Cltri<I tlrroublr tire small openirtb and orrt of the chamber, by moving up and down with respect to the clranth~r.
At any given position within tire ciraruher SF, tire lrlrrttger bead 6_I
therefore forms an enclosed cavity witlritr tire cltmuber, the cavity lreitrg open only, tltrouglr the small opening 60. Advancinb tire player into tire clratuber r~clnces the cavity's volume, driving tire contents of tire cavity out tltroublr tile sruall openiul;.
Wltert the plunger is fully advanced clown into tire cltanrlrer, the cavity's volrrtne is lowered to essentially zero, anc! tire cavity is emlrtied of srrl>starttially all fluid or gas tlrrouglt tire small opening. A fully advanced plrrnber, therefore, el~lectively c:vactrates Ilte syringe. Retracting the lrlunger from tire clr,ma(~er increases the voltrtrre of tlrc cavity, slurs drawing fluid or gas into tire cavit~~.
'1'lte mounting lutb S6 is a block-like slructurc, an Itpper chef of wlriclr conforrrtirtgly receives tire lower end of the syrinl;e body S0, lroldinl; the syritrt;e Uoci~, rigidly in place relative to Ilte frame. An it(111esrVe StICII 1S ~I)0?~)' is used to frond the syrittgc body to Ilte mounting ftub. 'flte mourrtinb loth defines a hollow sprats 66 providing a corridor for tire needle 52 to extend clown froth tile Cllilllll)er'S Stlritll opening 60.
'fire needle S2 Iris bout an outer shell 6F, and a concentric, hollow inner trrpre 7U extending tltroublr the older shell. An upper earl of tire irtrrer l W is alTixed tc~
the syringe body, such as by epoxy. It is affixed to tire small opening of tire syringe body, providing a vertical passage 72 in communication with tire chamber through the small opening. The inner tube extends down from the small opening 60 to a lower tip 74 of the needle. The passage has a generally constant cross sectional area, which necks down to form an orifice at the lower tip of the needle. The orifice preferably ranges from .005 in. to .010 in. in diameter.
Tire needle's outer shell 68 extends from tire lower tip 74 of the needle 52, up to a lower end of the mounting lmb 56. The outer shell has a generally consistent cross section that necks down at its lower end to merge with tire inner tube's lower end, forming the lower tip of the needle. Tire needle's outer shell is affixed to the lower end of the mounting hub, such as with epoxy, providing sh-rrctural support to the needle and holding the needle rigidly in place relative to tire frarne 12 and the syringe body 50.
The needle's lower tip 74 provides a contact surface 76 that is preferably not convex, and that is most preferably substantially flat and horizontal, the contact surface including both the lower end of the inner tutee 70 and the lower end of the outer shell 68. This horizontal contact surface is srnootlr, providing a substantial area to support a drop at tire lower tip of the needle 52. Tlurs, tire syringe 1~l for-rns a container, having an orifice at the needles lower tip, and being configured to pass fluids from within the container out through the orifice.
Preferably, the contact surface has a diameter ranging between .030 in.
and .090 in. As the size of the contact surface increases, the stability of a drop suspended from the contact surface increases. I-Iowever, the final concentrated size of a drop banging from the contact surface can be reduced from its original size, and thus, after concentration, a larger contact surface may cause the drop to be difficult to see.
rurihennore, a larger contact surface can lead to surface tension forces that make it diffrcult to remove the drop from the contact surface.
While the above-described components of the syringe l~t are preferred, a wide variety of components fall within the definition of, or are equivalent to, a syringe.
In particular, a syringe as claimed could be embodied in any device drat can controllably pass a substance from a chamber out of an orifice, where tire emission of the substance is controllable. Likewise, for syringes having a body, a needle, and a plunger, a wide variety of configurations are within the scope of the invention. Por example, a horizontally oriented body, a plunger and a needle, that can provide the same essential fimctions of the vertical syringe, fall within the scope of tire invention.
Components that are to come into contact with the solution, and particularly with the solution after it has been concentrated, are~preferably made of materials compatible with the solution. Tlrus, the needle 52 and tire body 50 are preferably made from duartz.
Returning to rlGS. lA and 2A - 2I3, the table 24 is confil;ured to be laterally positionable vertically below the needle 52. Tlre first motor 28 can laterally adjust the table's position, by use of the screw drive 30, so as to place either tire heater 38 or the platter 32 directly below the needle. The platter is configured to carry a plurality of vessels, such as vials, each of which can be laterally positioned directly under the needle by the first motor. A first vial 80 of the plurality of vessels contains a fluid for flushing the syringe 14, such as tire solvent, water. A second vial 82 of tire plurality of vessels contains a dilute solute in solvent, such as dilute radioactive orthophosphoric acid in water.
Preferably, tire viols 80, 82 are received in spring-loaded Ir,rys ti.l irr the platter 32. Tlre spring-loaded bays provide protection against the needle 52 breakine if it strikes the bottom of one of tire vials.
Tlre lreater 3S, wlriclr is configured to beat a drop of llrrid suspended fronn tire lower- tip 7~1 of tire needle 52, can Ire of a wide variety of clesi~ns. 1'referalrly tire beater is configured to beat and evaporate tire drop by creatinb a column of heated bas (lowinb up arrd around tire drop. 'fire gas can be air or any other srrbslance drat would allow and encoura6e the evaporation of the solvent. 1'refera(ly the bas is an inert has such as nitrogen. 1'lre gas is treated to a soft icient level to encourage the evaporation of the solvent.
lvor example, tire beater can be a verlic~ll~~ oriented coil of a resistor wire, wlriclr can be heated by the application of a voltabe across tlrc wire.
Srrclr a Beater beats tire air in the vicinity of the wire, wlriclr urea rises tlrrorrglr tire cooler surrounding air to form a column of heated air.
A preferred heater, as seen in 1~IG~. ~IA - ~1C, inclrrcles tr tatty OU and a valve: O2. t1n inlet 9~1 on tire body is configured to receive exparulinl;
l;as, lrref~raUly being nitro6en, from a pressurized supply (not shown). Gas received by the inlet expands tlrrouglr a tubular main passage 96, wlriclr is partially surrounded by a beater element 98, preferably being a nicbrorne wire spiraled alonb the outside of tire hod~~, the wire hein~ encased in a Biglr-temperature epoxy. Passing tlworrl;lr tlrrr main passage, ilre gas is directed by tyre valve tlrrouglr one of two Irons, Ireirrg a concentration port 100 anti a final-evaporation port 102.
'flre valve 92 includes a tubular portion 10=I, tlrc exterior oC wlriclr conlorms to the interior of the heater body's maim ~assa8e 9G so as to receive tire gas into the valve. Two holes 106 in the valve's tubular portron are configured to allow il~e gas to pass through only one port 100, 102 at a time, which can be selected by rotatiorrally positioning the valve to align one hole with the selected port.
Tlie valve can be manually operated, or can be configured to be controlled by the computerized control system.
The concentration port 100 is a round vertical tube conFgured to form a column of air having an approximately round cross section when the beater 38 is activated. Tlre final-evaporation port 102 is configured to form a column of air having a band-shaped cross-section, having a larger clirnension and a smaller dimension. The final-evaporation port includes a diffusion screen 108 to produce a column of heated air having a more even distribution of heat over its cross-section.
As seen in rIGS. lA - 1C, as well as rIGS SA - 513, the pick-off device 22 is configured to retain a source 110, being a preferably tubular appliance configured to receive the drop of concentrated solution after the process of concentrating the solution on the syringe is complete. The pick-off device is further configured to position and move the retained source, while moving into contact with the drop to receive the drop from the syringe. ror proper positioning, the pick-off device includes a top adjustment screw 112, a side adjustment screw 114, and a front adjustment screw 116. ror use with radioactive solutions, these screws can include long shafts so that they can be used from outside of a radiation shield (not shovm) around the apparatus 10.
1'he source I 10, which can take numerous forms, preferably takes the for-rn of a thin hollow tube perforated with a plurality of holes, the tine being configured to draw a drop of fluid into the hrbe with capillary forces.
Preferably, the source is sized to precisely contain one drop of solution.
The high-resolution camera 20 is equipped with a zoom lens 118, and is configured to image a drop of fluid being suspended from the needle's lower tip 74.
The image can be displayed on a monitor (not shown) for an operator of the apparatus 10. The camera's configuration can also image the source 110.
Under the power of tire second motor 34, tire platter 32 is configured to vertically move the plurality vials with respect to the syrinl;e 14. Using the second screw drive 36, tire platter can be raised by the second motor such drat tire needle 52 extends fully into a vial that is located directly below tire needle, as can be seen in fIG.
6B. Likewise, the platter can be lowered such that a vial directly tinder the needle is entirely below the lower tip 74 o~'the needle, as seen in PIG. 6A, allowing tire vials to pass laterally below the needle without contacting the needle. It is preferable that the platter is configvrred to lower to a level that is convenient for posrtronrng and removing vials without sil;nificant risk of the vials hitting the needle, such as tire level depicted in rIG. 2A.
As seers in I:IGS. lA - 1C and 2A - 2B, a rnetlrod embodying tire present invention for concenri~atinl; the amount of a solute in solution with a solvent to a prescribed concentration begins by setting up tire above described apparatus and adjusting it for use. In parUicular, tire syringe-adjuster 26 is actuated to vertically adjust tire position of the syringe such that the lower tip 74 of the needle 52 resides slightly above the measurement zone of the laser micrometer 18, tlnrs configuring the laser micrometer to measure the size of a drop of solution suspended from the needle while the drop is still hanging from the needle. The stepper motor 16 firll~~
advances tire plunger 54 into the syringe body 50 to minimize the clamber size and effectively evacuate the syringe.
WO 99/62607 PG"T/US99/12554 Additionally, the heater valve 92 is adjusted to direct flue lrentui bas tlrroubir tire concentration port 100. 'fire source l 10 IS rnounted arul retainer! in tire pick-off device 22 (as seen in rIG. SI3), which is adjusted by its adjustment screws to hold tire source in close proximity to tire needle for fast and convenient use alter the solution has peen concentrarted ty the syrinbe l~t. 'l'lris position, however, must lie selected to not interfere with the operation of the apparatus' components, such as the laser micrometer 18. Two vials are positioned on the platter 32. '1'lve first vial 80 contains a solvent, such as water, to he used for flushing the syrirrbe.
'1'lie second vial 82 contains a dilute solution of a solute in a solvent, hreferalrly lrciab tire same solvent as is contained in solution in the f first vial.
With the apparatus 10 set uh and adjusted, it is olUion,rlly (and preferably) flushed and tested prior to evaporatively concentrating the solution. 'fire plrurger S4 is withdrawn from lire syringe body SO Iry the stelrlrer motor 1 C
to cause a predeter-ruine<l amount of air to tie drawn into the cavity of the clraW rer St;. 'fire table 2~1, with Ilre platter 32 adjusted such drat tire vials 80, F2 are low enough to pass laterally below tire needle S2, is laterally adjusted to place tire first vial FO directly below Ilre needle, as seen in PIG. 6A. hIGS. 6A - fit-: do not clelrict tlic laser micrometer and a pick-off device to better illustrate the positions of the umlerl~~inl;
harts of tire apparatus 10.
'fhe first viol 80 is vertically adjusted such drat tlri: needle S? extends into thi; first vial, and into lire solvent tlrerein, as seem in 1-~IG. fil3.
'I'Ire steplrer motor IC firrther witlolra~,vs tire plunger S4 from tire syringe body S0 by a calculated amount, making the clramher S8 larger, and tlurs drawing a predeterruined duantity ol' the solvent from the first vial into the syringe ciramher. Tire platter 32 is then lowered Io a position low enough to allow tire vials to hiss under the needle.
I'rel~raUly, tire platter is lowered to its lowest position, where it cannot interfere with Ilrc operation c~( tS
the laser micrometer 18 or the view of tire camera 20. The table 24 is then moved longihrdinally such that the concentration port 100 of the heater 38 is directly below the needle, as seen in rIG. 6C.
The solvent in the syringe chamber 58 is then evaporated dowry to the volume of a drop, using the same evaporation method as is described in more detail below for evaporatively concentrating the solution in the second vial 82. Tire solvent is passed out of the needle to form a drop suspended from tire needle; the drop size is measured; some of the solvent is evaporated; and the volume of tire drop is replenished to maintain the drop's size. When the solvent in tire syringe chamber is preferably reduced to a single drop, the table is moved longitudinally and vertically to a position such that the plunger can be advanced fully into the clrarnber to eject the remaining;
drop of solvent back into the first vial, such as tire position depicted in PIG. 6A.
After the apparatus 10 is set up and adjusted, and after it is optionally flushed and tested, a procedure similar to the flush and test procedure is used to evaporatively concentrate the solution in tire second vial 82. T'he plunger 54, which is fully advanced into the syringe body S0, is withdrawn from tire syringe body by the stepper motor 16 to cause a predetermined amount of air to lie drawn into the cavity.
Nahrrally, in tire parlance of this application, air can be any environment deemed preferable to conduct the procedure. The table 24, with the platter 32 adjusted such that the vials 80, 82 are low enough to pass laterally below the needle 52, is laterally adjusted to place dye second vial directly below the needle, as seen in rIG.
6I7.
The second vial 82 is vertically adjusted such that tire needle 52 extends into the dilute solution in the second vial to a depth adequate to draw a predetermined quantity of solution from tire vial, as seen in T'IG. 6C. The stepper motor 16 further withdraws the plunger 54 from the syringe body 50 by an amount selected to draw tire predetermined amount of the solution up through tire needle's hollow inner tale 70 and into the cavity. Preferably, the air previously drawn into the chamber separates the solution from the plunger's head 64, minimizing potential chemical degradation of either the plunger's bead or the solution by contact with each other.
The platter 32 is then lowered to a position low enough to allow the vials 80, 82 to pass under the needle 52 without coming into contact with the needle, or any drop of solution drat might be hanging from tire needle. If a drop is visibly hanging from the needle, the stepper motor tnay further withdraw the plunger from the syrirrge to draw the drop into the needle. Preferably, tire platter is lowered to its lowest position, where it cannot interfere with the laser micrometer I 8 or block the view of the camera 20 during evaporation. The table 24 is then moved longitudinally such drat the concentration port 100 of the heater 38 is directly below tire needle 52 to provide for evaporation of the solvent in the solution, as is seen in rIG. 6C.
Once the heater's concentration port 100 is positioned below tire needle 52, the laser micrometer takes an initial measurement of the diameter of any drop (ranging from the contact surface 78 at the lower tip 74 of tire needle.
The measurement of the drop is relayed to the computerized control system, which preferably controls the stepper motor to draw tire drop up into tire needle.
The heater is then preferably used to dry the exterior of the needle to prevent solution from later being hulled up the needle by surface tension forces.
Under the control of tire computerized control system, tire stepper motor 16 then causes the syringe 14 to produce a drop. Tlre laser micrometer 18 measures tire drop and compares the measurement with prescribed limits, being a prescribed minimum size and a prescribed maximum size. The Prescribed maximum size is selected such that surface tension forces will. reliably suspend the drop li~om tile contact surface 78 at the lower tip of the needle.
The prescribed minimum size is selected to be lame enough such that tile suspended solution is in contact with sufficiently little solid material (i.e., on the contact surface) to avoid significant precipitation and plating of solute as the solvent evaporates. It is also selected to be large enough to provide an acceptably fast evaporation rate. The prescribed minimum size is selected to be small enou6ll such that its difference from the maximum size is adeduate to accommodate tile tolerance of the stepper motor 16 (i.e., its ability to cause the emission of enough dilute solution to exceed the prescribed minimum size, but not to exceed the prescribed maximum size).
Preferably, there is little or no change in the amoluU of contact area behveen the drop and the contact surface so long as the drop is between tile Il1lI11lrlllln aIld maximum sizes, and thus the contact surface remains wet.
Under control of the control system, the stepper motor 16 advances the plunger to pass dilute solution out of the needle to the formed or forming drop, or retracts the plunger to draw solution from the drop into the needle, to adjust the size of the drop such that its measurement is greater than the prescribed rninimum measurement and less than the prescribed maximum measurement. As before, the solution is passed out of the needle or drawn into the needle by moving tile plunger 54 further into, or out of, the syringe body 50, respectively.
With tire drop adjusted to be within the prescribed limits, the heater 38 is activated to create a column of heated gas flowing over the drop llanglng from the needle 52. In particular, with reference to I:IGS. 4A - 4C, pressurized nitrogen gas is released from its supply (not shown), through the heater's inlet 94, throu6ll tile main passage 96 and out through the concentration port 100. The heater element 98 is energized, which in turn heats tire nitrogen gas as it passes through the main passage.
The heater is configured to create a column of heated gas sufficient to cause evaporation of solvent from within the drop. While the above-described beater is the prefewed embodiment of the heater, any device configured to accelerate the rate of the solvent's evaporation, whether through temperature, barometric pressure, or other relevant factors, is within the scope of the invention. While it is preferable that tire heater is energized when the drop is within tire prescribed limits, it is well within the scope of the invention to energize the heater prior to passing any solution out of the needle.
The column of heated gas evaporates some of tire solvent within the drop, causing the volume of the drop to be reduced and the size of the drop to shrink.
While the solvent within the drop is evaporating, the laser micrometer monitors the drop by continuing to measure the size of the drop. The measurements are relayed to the control system, which compares the measurements with tire prescribed limits.
Returning to rIGS. IA - 1C and 2A - ZI3, when tire size of tire drop falls below the prescribed minimum, the control system instincts the stepper motor 1G to advance the plunger 54 into the syringe body 50, increasing tire size of the drop to a size larger than tire prescribed minimum. Preferably, tire plunger is not advanced far enough to make the drop larger than the prescribed rrlaXllllilllr Slze, as it is not preferable to draw concentrated solution back into the needle 52.
Preferably, the needle is configured to he nawow enough near tire orifice to substantially prevent the concentrated solution fr'OIrl diffusing rrp tire needle durinf;
tire evaporation. hurtherntore, the stepper motor and heater are preferably configured, and the prescribed minimum and maximum sizes are preferably chosen, to provide for evaporation and addition of solution to occur at a rate allowing near-continuous a<lclition, so as to substantially prevent concentration gradient diffusion from tire evaporating mixture as it becornes more concentrated.
The size of the drop is continuously monitored and adjusted until enoug;lr solvent has been evaporated to cause the drop to reach a prescribed concentration of solute in solution with tire remaining; solvent, or until all of the dilute solution in tire syringe passes out into the drop. Depending; on tire desired concentration, it might be necessary to frlrther concentrate the drop, reducing its size below tile prescribed minimum. As the drop reaches the desired concentration, the greater is turned off, so as to stop or limit any filrther evaporation.
Little or no precipitation occurs on the contact surface 78 so long as tire drop is maintained between tire minimum and IrIaXIIrlrrrrl SIZeS. Preferably, tile contact surface is shaped, sized and oriented such that the contact area between it and the drop changes little (or not at ail) if the drop is to be shrunk below the minimum size. ror such a contact surface, little or no precipitation occurs on the contact surface even when tire drop is reduced below the minimum size.
The resulting drop of concentrated solution may then be removed from the needle 52. 1n tlris embodiment, tire concentrated solution is used to form a substantially uniform coating of solute plated within the source 110.
Preferably, tire drop of concentrated solution is removed from the needle by touclring the bottom ed6e of tire drop with the center of the source. Upon touching the source, the drop is drawn into the source through its perforations by capillary action, pulling the drop off of the needle.
The position of the source is adjusted to touch tire drop throul;ll tire use of the pick-off device's top adjustment screw I 12, side adjustment screw 1 l~l, and front adjustment screw 116. While the above describes the preferred embodiment, a variet~~
of pick off techniques are envisioned as within the scope of the invention.
Por example, an open end of the source can be touched to the side of the drop, drawing the drop into the end of the source by capillary forces.
As seen in FIGS. SA - SI3, tire concentrated solution within the source 110 is then heated to evaporate the solvent, precipitating the solute and causing it to plate onto the source, forming a layer of solute in the interior of the source. To do so, the table is first laterally adjusted to position the heater's final-evaporation port 102 under the source. The heater valve 92 is then actuated to align the concentration-port valve's hale (see 106 in FIG. 4A) with the final-evaporation ,port. Tlre nitrogen gas is again passed through the heater with the heater element energized, causing a band-shaped, diffused column of heated air, which approximates the shape of the source, to rise up to the source and evaporate the last of tl~e solvent.
lxample An number of experimental nrns have been ruade in the ambient conditions comprising an air temperature of 90-95 ° C. Tlte syringe was configured with a needle having a .OIO in. bore, which reduced to .005 in. at tire lower tip (i.e., at the orifice). The needle also had a .090 in. outer diameter, which reduced to .070 in. at the lower tip.
A dilute solution of radioactive ortltophosphoric acid in water, exhibiting approximately 1.5 - 2.0 mCi/mm3 was used as the starting material. After the syringe was set up and adjusted, and was flushed and tested with water, 225 mnt' of the dilute solution were drawn up into the syringe. The size of the suspended drop, which was estimated to have adequate surface tension forces to support a drop size up to ~1 mrn, WO 99/b2607 PCT/US99/12554 was approximately maintained in the vicinity of 2.~1 mm (1 .2) mm for sal~~t~~. llho«
heating, evaporation typically occurred at rates of S a«n'/miu. At this rate, flue (1«id velocity through tire orifice averaged 395 mm/rui«., effectively peeve«tillg diffusion hack lllrougli the orifice. Tlle volume of tile concentrated drop vws in tll~
vie;iait~~ of .t~
men', which exhibited 200 - 350 mCi, an<I preferably 300 mCi.
'flee above-described metltocl and ahparat«s embody a broad array of novel li:atlrres of the invention. However, these features :Ira not limited is scone Ily the descrilaed embodiments, as n«mero«s other embodiments are willtin Ille scope of the invention. To demonstrate the breadth of the i«ventioll, a «lllnller of embodiment variations are discussed below.
'flee described embodiments characterize tile solution as sllshe«decl in air.
However the invention is equally applicable to any cnvironnlent, gascolls clr otherwise, tlral allows tile solution to be s«spe«ded witflirl it, ,nut that can accolnnmlalo tile removal of the sot«tio«'s solvent, s«clr as by evaporation.
l~nrtlyermore, the removal of the sot«tioll's solve) does not necessarily )lave to be accelerated by the addition of heat. Other euvironllle«tal cllaracteristics, s«clt as pressure, may instead he varied to improve tile evaporation rate.
lncle~el, tile solvent could he allowed to evaporate without any stirnlllation, altllollgll it could ~re1lly len~tllen the necessary tithe for many emlaodirnents.
'lvvo aspects of the invention have been described as simullaneoltsl~- used to minimize the precipitatio« of solute d«rin~ evaporation. 'l'lle first aspect is tlm suspension of tile solution such that it is in contact with little sllrlilce area of a contact surface, Irrovidin~ for little or no change in the contact s«rface area.
'I'lle second aspect is tile adclilion of dilute s~IWion to the glollule of sollltiorl (O
Illallllillll the vt>Illlll(' of combined SOlI1I10r1 Wltllllr 1 bound, providing for little or no cllauge in the contact surface area. >;ach of these aspects may lie used individually within the scup of the invention.
rrom the foregoing description, it will be appreciated that the present invention provides a method and apparatus to concentrate a solute in solution with a solvent, without the inefficiencies and problems associated with conventional evaporative systems. While particular fornis of the invention leave been illustrated and described, it will be apparent that various other modifications can be made without departing from the spirit and scope of the invention. Thus, although tile invention has been described in detail with reference only to the preferred ernbodunents, those having ordinary skill in the art will appreciate that various modifications can be made without departing from the invention. Accordingly, the invention is not intended to lie limited, and is defined with reference to the following claims.
Claims
We Claim:
1. A method of forming a concentrated mixture, leaving a prescribed concentration of a substance mixed with a fluid, from a comparatively dilute mixture, comprising:
evaporating fluid from a quantity of the dilute mixture until the concentration of the evaporating mixture reaches the prescribed concentration; and adding additional dilute mixture to the evaporating mixture to maintain the amount of evaporating mixture above a prescribed minimum amount.
2. The method of claim 1, wherein:
the substance is a solute;
the fluid is a solvent for the solute; and the mixture is a solution formed from the solute in the solvent.
3. The method of claim 2, wherein the step of adding additional dilute mixture includes measuring the amount of evaporating mixture to determine if it is between the prescribed minimum amount and a prescribed maximum amount.
4. The method of claim 2, wherein the step of evaporating the fluid includes heating the evaporating mixture.
5. The method of claim 2, wherein the step of evaporating fluid comprises energizing a heater configured to pass a stream of heated gas over the evaporating mixture.
6. The method of claim 1, wherein:
the additional dilute mixture for the step of adding additional dilute mixture is provided in a chamber of a syringe having a plunger and an orifice, the plunger being advanceable into the clamber to pass the dilute mixture through the orifice;
the step of adding additional dilute mixture includes advancing the plunger into the chamber to pass dilute mixture through the orifice and into the evaporating mixture; and the step of adding additional dilute mixture maintains the amount of evaporating mixture between the prescribed minimum amount and a prescribed maximum amount.
7. The method of claim 6, wherein a motor advances the plunger into the chamber.
8. The method of claim 6, wherein the syringe further contains a quantity of gas, and wherein the syringe is oriented such that gas forms a buffer between the plunger and the dilute mixture.
9. The method of claim 6, wherein:
the substance is a solute;
the fluid is a solvent for the solute;
the mixture is a solution formed from the solute in the solvent;
the step of evaporating fluid comprises energizing a heater configured to pass a stream of heated gas over the evaporating mixture;
a motor advances the plunger into the chamber;
the syringe further contains a quantity of gas, the syringe being oriented such that gas forms a buffer between the plunger and the dilute mixture; and the step of adding additional dilute mixture includes measuring the amount of evaporating mixture to determine if it is between the prescribed minimum amount and the prescribed maximum amount.
10. A method of concentrating a solution to a prescribed concentration of a radioactive solute in a solvent, from a comparatively dilute solution, comprising:
evaporating solvent from a quantity of the dilute solution until the concentration of the evaporating solution reaches the prescribed concentration; and adding additional dilute solution to the quantity of dilute solution to maintain the amount of evaporating solution above a prescribed minimum amount.
11. The method of claim 10, wherein the step of adding additional dilute solution includes measuring the amount of evaporating solution to determine if it is between the prescribed minimum amount and a prescribed maximum amount.
12. The method of claim 10, wherein the step of evaporating the fluid includes heating the evaporating solution.
13. The method of claim 10, wherein the step of evaporating fluid comprises energizing a heater configured to pass a scream of heated gas over the evaporating solution.
14. The method of claim 10, wherein:
the additional dilute mixture for the step of adding additional dilute mixture is provided in a chamber of a syringe having a plunger and an orifice, the plunger being advanceable into the chamber to pass the dilute mixture through the orifice;
the step of adding additional dilute mixture includes advancing the plunger into the chamber to pass dilute mixture through the orifice and into the evaporating mixture; and the step of adding additional dilute mixture maintains the amount of evaporating mixture between the prescribed minimum amount and a prescribed maximum amount.
15. The method of claim 14, wherein a motor advances the plunger into the chamber.
16. The method of claim 14, wherein the syringe further contains a quantity of gas, and wherein the syringe is oriented such that gas forms a buffer between the plunger and the dilute solution.
17. The method of claim 14, wherein:
the step of evaporating fluid comprises energizing a heater configured to pass a stream of heated gas over the evaporating solution;
a motor advances the plunger into the chamber;
the syringe further contains a quantity of gas, the syringe being oriented such that gas forms a buffer between the plunger and the dilute solution; and the step of adding additional dilute solution includes measuring the amount of evaporating solution to determine if it is between the prescribed minimum amount and the prescribed maximum amount.
18. A method of forming A concentrated mixture, having a prescribed concentration of a substance mixed with a fluid, from a comparatively dilute mixture, comprising:
evaporating fluid from a quantity of the dilute mixture until the concentration of the evaporating mixture reaches the prescribed concentration; and adding additional dilute mixture to the evaporating mixture such that substantially no concentration gradient diffusion occurs from the evaporating mixture as it becomes more concentrated.
19. The method of claim 18, wherein:
the substance is a solute;
the fluid is a solvent for the solute; and the mixture is a solution formed from the solute in the solvent.
20. The method of claim 19, wherein the step of adding additional dilute mixture occurs at a rate allowing near-continuous addition so as to substantially prevent concentration gradient diffusion from the evaporating mixture as it becomes more concentrated.
21. The method of claim 20, wherein the step of adding additional dilute mixture includes measuring the amount of evaporating mixture to determine if it is between a prescribed minimum Amount and a prescribed maximum amount.
22. The method of claim 20, wherein the step of evaporating fluid comprises energizing a heater configured to pass a stream of heated gas over the evaporating mixture.
23. The method of claim 18, wherein the step of adding additional dilute mixture includes passing such additional dilute mixture through a passageway that is configured as narrow enough to substantially prevent concentration gradient diffusion from the evaporating mixture as it becomes more concentrated.
24. The method of claim 23, wherein:
the additional dilute mixture for the step of adding additional dilute mixture is provided in a chamber of a syringe that includes a plunger, the passageway and an orifice, the plunger being advanceable into the chamber to lass the dilute mixture through the passageway and through the orifice;
the step of adding additional dilute mixture includes advancing the plunger into the chamber to pass dilute mixture through the orifice and into the evaporating mixture; and the step of adding additional dilute mixture maintains the amount of evaporating mixture between a prescribed minimum amount and a prescribed maximum amount.
25. The method of claim 24, wherein:
the substance is a solute;
the fluid is a solvent for the solute;
the mixture is a solution formed from the solute in the solvent;
the step of evaporating fluid comprises energizing a heater configured to pass a stream of heated gas over the evaporating mixture;
a motor advances the plunger into the chamber;
the syringe further contains a quantity of gas, the syringe being oriented such that gas forms a buffer between the plunger and the dilute mixture; and the step of adding additional dilute mixture includes measuring the amount of evaporating mixture to determine if it is between the prescribed minimum amount and the prescribed maximum amount.
26. A method of precipitating a solute from a quantity of solution, onto a surface, the quantity of solution being at an initial concentration, comprising:
evaporating solvent from a first portion of the quantity of solution to concentrate the quantity of solution to a prescribed concentration that is higher than the initial concentration;
adding further portions of the quantity of solution to the evaporating solution to maintain the amount of evaporating solution above a prescribed minimum amount during the step of evaporating solvent to concentrate the quantity of solution; and evaporating solvent from the quantity of solution, after the step of evaporating solvent to concentrate the quantity of solution, and after the step of adding further portions of the quantity of solution to the evaporating solution, to precipitate the solute onto the surface.
27. The method of claim 26, wherein the surface is the interior of a hollow tube, and further comprising drawing the quantity of solution into the tube after the step of evaporating solvent to concentrate the quantity of solution, and prior to the step of evaporating the solvent to precipitate the solute onto the surface.
28. The method of claim 26, wherein the step of evaporating solvent to concentrate the quantity of solution, and the step of evaporating the solvent to precipitate the solute onto the surface, each include beating the evaporating solution to accelerate the evaporation of solvent.
the step of adding additional dilute mixture includes measuring the amount of evaporating mixture to determine if it is between the prescribed minimum amount and the prescribed maximum amount.
26. A method of precipitating a solute from a quantity of solution, onto a surface, the quantity of solution being at an initial concentration, comprising:
evaporating solvent from a first portion of the quantity of solution to concentrate the quantity of solution to a prescribed concentration that is higher than the initial concentration;
adding further portions of the quantity of solution to the evaporating solution to maintain the amount of evaporating solution above a prescribed minimum amount during the step of evaporating solvent to concentrate the quantity of solution; and evaporating solvent from the quantity of solution, after the step of evaporating solvent to concentrate the quantity of solution, and after the step of adding further portions of the quantity of solution to the evaporating solution, to precipitate the solute onto the surface.
27. The method of claim 26, wherein the surface is the interior of a hollow tube, and further comprising drawing the quantity of solution into the tube after the step of evaporating solvent to concentrate the quantity of solution, and prior to the step of evaporating the solvent to precipitate the solute onto the surface.
28. The method of claim 26, wherein the step of evaporating solvent to concentrate the quantity of solution, and the step of evaporating the solvent to precipitate the solute onto the surface, each include beating the evaporating solution to accelerate the evaporation of solvent.
32. A method of forming a concentrated solution, of a prescribed concentration of solute in a solvent, from a comparatively dilute solution, comprising:
suspending a globule of the dilute solution such that the globule is in contact with sufficiently little solid material to avoid significant precipitation of solute as solvent evaporates from the globule;
evaporating solvent from the suspended globule until the globule has reached the prescribed concentration of solute in the solvent; and adding additional dilute solution to the suspended globule during the step of evaporating solvent.
33. The method of claim 32, wherein the step of evaporating solvent is accelerated by a device configured to accelerate the rate of the solvent's evaporation.
34. The method of claim 32, wherein the step of evaporating solvent includes heating the suspended globule.
35. The method of claim 34, wherein the step of heating comprises passing a stream of heated gas past the suspended globule.
36. The method of claim 35, wherein the heated gas is nitrogen.
37. The method of claim 32, wherein the additional dilute solution added during the step of adding additional dilute solution maintains the amount of solution in the suspended globule above a prescribed minimum amount.
38. The method of claim 32, wherein the solution consists essentially of radioactive orthophosphoric acid in water.
39. The method of claim 32, wherein the suspended globule is is contact with a solid surface.
40. The method of claim 32, wherein the globule is a drop supported from a contact surface by surface tension forces during the step of evaporating solvent.
41. The method of claim 40, wherein the additional dilute solution added during the step of adding additional dilute solution maintains the amount of solution in the drop above a prescribed minimum amount.
42. The method of claim 40, wherein the step of evaporating solvent comprises energizing a heater configured to pass a stream of heated gas bast the drop.
43. The method of claim 40, wherein:
the additional dilute solution added during the step of adding additional dilute solution maintains the amount of solution in the drop above a prescribed minimum amount; and the step of evaporating solvent comprises energizing a heater configured to pass a stream of heated gas past the drop.
44. The method of claim 32, wherein:
the globule is a drop supported from a contact surface by surface tension forces during the step of evaporating solvent;
the step of adding additional dilute solution includes passing such additional dilute solution through an orifice in a container containing the dilute solution; and the additional dilute solution added during the step of adding additional dilute solution maintains the amount of solution in the drop above a prescribed minimum amount and below a prescribed maximum amount.
45. A method of forming.a concentrated mixture, of a measuring the amount concentration of a substance in a mixture with a fluid, from a comparatively dilute mixture, comprising:
suspending a drop of the dilute mixture from a contact surface by surface tension forces;
evaporating fluid from the drop until the drop has reached the prescribed concentration; and adding additional dilute mixture to the drop during the step of evaporating fluid.
46. The method of claim 45, wherein:
the substance is a solute;
the fluid is a solvent for the solute; and the mixture is a solution formed from the solute in the solvent.
47. The method of claim 46, wherein the step of evaporating fluid includes heating the drop.
48. The method of claim 46, wherein:
the step of adding additional dilute mixture includes measuring the amount of mixture in the drop to determine if it is above a prescribed minimum amount; and the additional dilute mixture added during the step of adding additional dilute mixture maintains the amount of mixture in the drop above the prescribed minimum amount.
49. The method of claim 45, wherein:
the dilute mixture is provided in a chamber of a syringe having a plunger and an orifice, the plunger being advanceable into the chamber to pass the dilute mixture through the orifice;
the step of suspending a drop includes advancing the plunger into the chamber to pass dilute mixture out of the chamber through the orifice; and the step of adding additional dilute mixture includes further advancing the plunger into the chamber to bass dilute mixture through the orifice and into the evaporating mixture; and the step of adding additional dilute mixture maintains the amount of mixture in the drop between a prescribed minimum amount and a prescribed maximum amount.
50. The method of claim 49, wherein a motor causes the plunger to be advanced in the step of suspending a drop and the step of adding additional dilute mixture.
51. The method of claim 49, wherein the syringe further contains a quantity of gas, and wherein the syringe is oriented such that gas rises to form a buffer between the plunger and the dilute mixture.
52. The method of claim 49, wherein the step of adding additional dilute mixture includes measuring the amount of mixture in the drop to determine if it is between the prescribed minimum amount and the prescribed maximum amount.
53. The method of claim 49, wherein the mixture is radioactive orthophosphoric acid in water.
54. The method of claim 49, wherein the step of evaporating fluid comprises energizing a heater configured to pass a stream of heated gas over the suspended drop.
55. The method of claim 49, wherein:
the substance is a solute;
the fluid is a solvent for the solute;
the mixture is a solution formed from the solute in the solvent.
the step of evaporating fluid comprises energizing a heater configured to pass a stream of heated gas over the suspended drop;
the plunger is advanced into the chamber by a motor during the steps of suspending a drop and adding additional dilute mixture;
the syringe further contains a quantity of gas, and wherein the syringe is oriented vertically such that gas rises to form a buffer between the plunger and the dilute mixture; and the step of adding additional dilute mixture includes measuring the amount of mixture in the drop to determine if it is between the prescribed minimum amount and the prescribed maximum amount.
56. An apparatus for forming a concentrated mixture, of a prescribed concentration of substance in a fluid, from a comparatively dilute mixture, comprising:
a syringe configured to suspend a drop of the dilute mixture after passing it through an orifice; and a measuring device configured to gauge the amount of mixture in a drop suspended by the syringe.
57. The apparatus for forming a concentrated mixture of claim 56, the syringe defining a passageway that is configured as narrow enough to substantially prevent concentration gradient diffusion from the evaporating mixture as it becomes more concentrated.
58. The apparatus for forming a concentrated mixture of claim 56, the syringe comprising:
a body having a chamber defining an opening;
a needle in communication with the opening, the needle defining the orifice;
and a plunger movable into and out of the chamber;
wherein the plunger can be advanced into the chamber to pass mixture out of the chamber and through the orifice; and wherein the plunger can be withdrawn from the chamber to draw mixture into the chamber through the orifice.
59. The apparatus for forming a concentrated mixture of claim 56, and further comprising a heater configured to evaporate the fluid from the drop.
60. The apparatus for forming a concentrated mixture of claim 56, wherein the measuring device is a laser micrometer.
61. The apparatus for forming a concentrated mixture of claim 56, and further comprising a motor configured to actuate the syringe to pass dilute mixture through the orifice.
62. The apparatus for forming a concentrated mixture of claim 61, wherein the motor actuates the syringe at a rate allowing near-continuous addition of dilute solution so as to substantially prevent concentration gradient diffusion from the evaporating mixture as it becomes more concentrated.
63. The apparatus for forming a concentrated mixture of claim 56, and further comprising a platter that's position can be both vertically and laterally adjusted.
64. The apparatus for forming a concentrated mixture of claim 56, and further comprising a platter that's position can be both vertically and laterally adjusted, the platter including one or more spring-loaded bays.
65. The apparatus for forming a concentrated mixture of claim 56, wherein the syringe is oriented such that gas in the syringe will rise to form a buffer between the plunger and the dilute mixture in the syringe.
66. The apparatus for forming a concentrated mixture of claim 56, and further comprising a computerized control system configured to control the emission of dilute mixture from the syringe in response to readings from the measurement device.
67. The apparatus for forming a concentrated mixture of claim 56, wherein the syringe includes a needle made from quartz tubing.
68. The apparatus for forming a concentrated mixture of claim 56, wherein the syringe includes a needle having a lower lip that provides a substantially flat and horizontal contact surface.
69. The apparatus for forming a concentrated mixture of claim 56, wherein the syringe includes a horizontal contact surface configured to suspend a drop produced by the syringe.
70. The apparatus for forming a concentrated mixture of claim 56, and further comprising a heater configured to evaporate fluid from a drop suspended by the syringe.
71. The apparatus for forming a concentrated mixture of claim 70, wherein the heater is a vertically oriented coil of a resistor wire configured to be energized by the application of a voltage across the wire.
72. The apparatus for forming a concentrated mixture of claim 70, wherein the heater is configured to selectively deliver heated gas through one of a plurality of ports, one of the ports being configured to form a substantially round column of heated gas, and another of the ports being configured to form band-shaped column of heated gas.
73. The apparatus for forming a concentrated mixture of claim 56, and further comprising a thin hollow tube perforated with a plurality of holes, the tube being configured to draw a drop of mixture, which has been produced by the syringe, into the tube under capillary forces.
74. The apparatus for forming a concentrated mixture of claim 56, and further comprising a heater configured to evaporate solvent from mixture suspended from the syringe, wherein the syringe comprises:
a body having a chamber defining an opening;
a needle in communication with the opening, the needle defining the orifice;
and a plunger movable into and out of the chamber;
wherein the plunger can be advanced into the chamber to pass dilute mixture out of the chamber and through the orifice;
wherein the plunger can be withdrawn from the chamber to draw dilute mixture into the chamber through the orifice; and wherein the needle includes a contact surface configured to suspend a drop produced by the syringe.
75. A method of forming a concentrated solution, of a prescribed concentration of solute in a solvent, from a comparatively dilute solution, comprising:
providing the apparatus for forming a concentrated solution of claim 74;
locating dilute solution in the chamber;
advancing the plunger into the chamber to pass the dilute solution through the orifice and form a drop of solution suspended from the contact surface, the size of the drop of solution being between a prescribed minimum size and a prescribed maximum size as measured by the measuring device;
and energizing the heater, while continuing the step of advancing the plunger, until the drop of solution has reached the prescribed concentration.
76. The method of claim 75, wherein the step of advancing the plunger is controlled by a computerized control system.
77. The method of claim 75, wherein the solution is a radioactive orthophosphoric acid in water.
78. The method of claim 75, wherein the step of locating the solution in the chamber comprises:
providing a vessel containing the dilute solution;
adjusting the relative positions of the vessel containing the dilute solution and the needle to bring the orifice into the solution;
withdrawing the plunger to draw a prescribed amount of the dilute solution into the syringe chamber; and adjusting the relative positions of the vessel containing the dilute solution and the needle to remove the orifice from the dilute solution.
79. The method of claim 78, wherein the step of locating the dilate solution in the chamber further comprises adjusting the plunger to locate a prescribed amount of air into the syringe prior to bringing the orifice into the dilute solution.
80. The method of claim 78, wherein prior to the step of locating the solution in the chamber the method further comprises:
providing a vessel containing a solvent of the type in the dilute solution;
adjusting the relative positions of the vessel of solvent and the needle to bring the orifice into the solvent;
withdrawing the plunger to draw a prescribed amount of the solvent into the syringe chamber;
adjusting the relative positions of the vessel and the needle to remove the orifice from the solvent;
advancing the plunger into the chamber to bass the solvent through the orifice and form a drop of solvent suspended from the contact surface, the size of the drop of solvent being between a prescribed minimum size and a prescribed maximum size as measured by the measuring device; and energizing the heater, while continuing the step of advancing the plunger, until the solvent has been evacuated from the chamber.
81. An apparatus for forming a concentrated solution, of a prescribed concentration of solute in a solvent, from a comparatively dilute solution, comprising:
a means for suspending a globule of the dilute solution such that solvent can be evaporated from the suspended globule; and a means for measuring the amount of solution in the globule.
82. The apparatus for forming a concentrated solution of claim 81, and further comprising a means for adding additional dilute solution to a globule of solution suspended by the means for suspending a globule.
83. The apparatus for forming a concentrated solution of claim 81, and further comprising a means for accelerating the evaporation of solvent from a globule of solution suspended by the means for suspending a globule.
84. The apparatus for forming a concentrated solution of claim 81, and further comprising:
a means for adding additional dilute solution to a globule of solution suspended by the means for suspending a globule;
a means for accelerating the evaporation of solvent from a globule of solution suspended by the means for suspending a globule; and a means for controlling the means for adding in response to readings from the means for measuring.
85. A method of precipitating substantially all of the solute from a quantity of dilute solution onto a precipitation surface, the volume of the quantity of dilute solution exceeding an amount that can be accommodated in contact with the surface without contacting other surfaces, comprising:
forming a concentrated solution from the quantify of dilute solution, the concentrated solution having substantially all of the solute that was in the dilute solution, wherein the volume of the concentrated solution does not exceed an amount that can be accommodated in contact with the precipitation surface without contacting other surfaces;
evaporating the remaining solvent from the concentrated solution to precipitate the solute onto the precipitation surface.
1. A method of forming a concentrated mixture, leaving a prescribed concentration of a substance mixed with a fluid, from a comparatively dilute mixture, comprising:
evaporating fluid from a quantity of the dilute mixture until the concentration of the evaporating mixture reaches the prescribed concentration; and adding additional dilute mixture to the evaporating mixture to maintain the amount of evaporating mixture above a prescribed minimum amount.
2. The method of claim 1, wherein:
the substance is a solute;
the fluid is a solvent for the solute; and the mixture is a solution formed from the solute in the solvent.
3. The method of claim 2, wherein the step of adding additional dilute mixture includes measuring the amount of evaporating mixture to determine if it is between the prescribed minimum amount and a prescribed maximum amount.
4. The method of claim 2, wherein the step of evaporating the fluid includes heating the evaporating mixture.
5. The method of claim 2, wherein the step of evaporating fluid comprises energizing a heater configured to pass a stream of heated gas over the evaporating mixture.
6. The method of claim 1, wherein:
the additional dilute mixture for the step of adding additional dilute mixture is provided in a chamber of a syringe having a plunger and an orifice, the plunger being advanceable into the clamber to pass the dilute mixture through the orifice;
the step of adding additional dilute mixture includes advancing the plunger into the chamber to pass dilute mixture through the orifice and into the evaporating mixture; and the step of adding additional dilute mixture maintains the amount of evaporating mixture between the prescribed minimum amount and a prescribed maximum amount.
7. The method of claim 6, wherein a motor advances the plunger into the chamber.
8. The method of claim 6, wherein the syringe further contains a quantity of gas, and wherein the syringe is oriented such that gas forms a buffer between the plunger and the dilute mixture.
9. The method of claim 6, wherein:
the substance is a solute;
the fluid is a solvent for the solute;
the mixture is a solution formed from the solute in the solvent;
the step of evaporating fluid comprises energizing a heater configured to pass a stream of heated gas over the evaporating mixture;
a motor advances the plunger into the chamber;
the syringe further contains a quantity of gas, the syringe being oriented such that gas forms a buffer between the plunger and the dilute mixture; and the step of adding additional dilute mixture includes measuring the amount of evaporating mixture to determine if it is between the prescribed minimum amount and the prescribed maximum amount.
10. A method of concentrating a solution to a prescribed concentration of a radioactive solute in a solvent, from a comparatively dilute solution, comprising:
evaporating solvent from a quantity of the dilute solution until the concentration of the evaporating solution reaches the prescribed concentration; and adding additional dilute solution to the quantity of dilute solution to maintain the amount of evaporating solution above a prescribed minimum amount.
11. The method of claim 10, wherein the step of adding additional dilute solution includes measuring the amount of evaporating solution to determine if it is between the prescribed minimum amount and a prescribed maximum amount.
12. The method of claim 10, wherein the step of evaporating the fluid includes heating the evaporating solution.
13. The method of claim 10, wherein the step of evaporating fluid comprises energizing a heater configured to pass a scream of heated gas over the evaporating solution.
14. The method of claim 10, wherein:
the additional dilute mixture for the step of adding additional dilute mixture is provided in a chamber of a syringe having a plunger and an orifice, the plunger being advanceable into the chamber to pass the dilute mixture through the orifice;
the step of adding additional dilute mixture includes advancing the plunger into the chamber to pass dilute mixture through the orifice and into the evaporating mixture; and the step of adding additional dilute mixture maintains the amount of evaporating mixture between the prescribed minimum amount and a prescribed maximum amount.
15. The method of claim 14, wherein a motor advances the plunger into the chamber.
16. The method of claim 14, wherein the syringe further contains a quantity of gas, and wherein the syringe is oriented such that gas forms a buffer between the plunger and the dilute solution.
17. The method of claim 14, wherein:
the step of evaporating fluid comprises energizing a heater configured to pass a stream of heated gas over the evaporating solution;
a motor advances the plunger into the chamber;
the syringe further contains a quantity of gas, the syringe being oriented such that gas forms a buffer between the plunger and the dilute solution; and the step of adding additional dilute solution includes measuring the amount of evaporating solution to determine if it is between the prescribed minimum amount and the prescribed maximum amount.
18. A method of forming A concentrated mixture, having a prescribed concentration of a substance mixed with a fluid, from a comparatively dilute mixture, comprising:
evaporating fluid from a quantity of the dilute mixture until the concentration of the evaporating mixture reaches the prescribed concentration; and adding additional dilute mixture to the evaporating mixture such that substantially no concentration gradient diffusion occurs from the evaporating mixture as it becomes more concentrated.
19. The method of claim 18, wherein:
the substance is a solute;
the fluid is a solvent for the solute; and the mixture is a solution formed from the solute in the solvent.
20. The method of claim 19, wherein the step of adding additional dilute mixture occurs at a rate allowing near-continuous addition so as to substantially prevent concentration gradient diffusion from the evaporating mixture as it becomes more concentrated.
21. The method of claim 20, wherein the step of adding additional dilute mixture includes measuring the amount of evaporating mixture to determine if it is between a prescribed minimum Amount and a prescribed maximum amount.
22. The method of claim 20, wherein the step of evaporating fluid comprises energizing a heater configured to pass a stream of heated gas over the evaporating mixture.
23. The method of claim 18, wherein the step of adding additional dilute mixture includes passing such additional dilute mixture through a passageway that is configured as narrow enough to substantially prevent concentration gradient diffusion from the evaporating mixture as it becomes more concentrated.
24. The method of claim 23, wherein:
the additional dilute mixture for the step of adding additional dilute mixture is provided in a chamber of a syringe that includes a plunger, the passageway and an orifice, the plunger being advanceable into the chamber to lass the dilute mixture through the passageway and through the orifice;
the step of adding additional dilute mixture includes advancing the plunger into the chamber to pass dilute mixture through the orifice and into the evaporating mixture; and the step of adding additional dilute mixture maintains the amount of evaporating mixture between a prescribed minimum amount and a prescribed maximum amount.
25. The method of claim 24, wherein:
the substance is a solute;
the fluid is a solvent for the solute;
the mixture is a solution formed from the solute in the solvent;
the step of evaporating fluid comprises energizing a heater configured to pass a stream of heated gas over the evaporating mixture;
a motor advances the plunger into the chamber;
the syringe further contains a quantity of gas, the syringe being oriented such that gas forms a buffer between the plunger and the dilute mixture; and the step of adding additional dilute mixture includes measuring the amount of evaporating mixture to determine if it is between the prescribed minimum amount and the prescribed maximum amount.
26. A method of precipitating a solute from a quantity of solution, onto a surface, the quantity of solution being at an initial concentration, comprising:
evaporating solvent from a first portion of the quantity of solution to concentrate the quantity of solution to a prescribed concentration that is higher than the initial concentration;
adding further portions of the quantity of solution to the evaporating solution to maintain the amount of evaporating solution above a prescribed minimum amount during the step of evaporating solvent to concentrate the quantity of solution; and evaporating solvent from the quantity of solution, after the step of evaporating solvent to concentrate the quantity of solution, and after the step of adding further portions of the quantity of solution to the evaporating solution, to precipitate the solute onto the surface.
27. The method of claim 26, wherein the surface is the interior of a hollow tube, and further comprising drawing the quantity of solution into the tube after the step of evaporating solvent to concentrate the quantity of solution, and prior to the step of evaporating the solvent to precipitate the solute onto the surface.
28. The method of claim 26, wherein the step of evaporating solvent to concentrate the quantity of solution, and the step of evaporating the solvent to precipitate the solute onto the surface, each include beating the evaporating solution to accelerate the evaporation of solvent.
the step of adding additional dilute mixture includes measuring the amount of evaporating mixture to determine if it is between the prescribed minimum amount and the prescribed maximum amount.
26. A method of precipitating a solute from a quantity of solution, onto a surface, the quantity of solution being at an initial concentration, comprising:
evaporating solvent from a first portion of the quantity of solution to concentrate the quantity of solution to a prescribed concentration that is higher than the initial concentration;
adding further portions of the quantity of solution to the evaporating solution to maintain the amount of evaporating solution above a prescribed minimum amount during the step of evaporating solvent to concentrate the quantity of solution; and evaporating solvent from the quantity of solution, after the step of evaporating solvent to concentrate the quantity of solution, and after the step of adding further portions of the quantity of solution to the evaporating solution, to precipitate the solute onto the surface.
27. The method of claim 26, wherein the surface is the interior of a hollow tube, and further comprising drawing the quantity of solution into the tube after the step of evaporating solvent to concentrate the quantity of solution, and prior to the step of evaporating the solvent to precipitate the solute onto the surface.
28. The method of claim 26, wherein the step of evaporating solvent to concentrate the quantity of solution, and the step of evaporating the solvent to precipitate the solute onto the surface, each include beating the evaporating solution to accelerate the evaporation of solvent.
32. A method of forming a concentrated solution, of a prescribed concentration of solute in a solvent, from a comparatively dilute solution, comprising:
suspending a globule of the dilute solution such that the globule is in contact with sufficiently little solid material to avoid significant precipitation of solute as solvent evaporates from the globule;
evaporating solvent from the suspended globule until the globule has reached the prescribed concentration of solute in the solvent; and adding additional dilute solution to the suspended globule during the step of evaporating solvent.
33. The method of claim 32, wherein the step of evaporating solvent is accelerated by a device configured to accelerate the rate of the solvent's evaporation.
34. The method of claim 32, wherein the step of evaporating solvent includes heating the suspended globule.
35. The method of claim 34, wherein the step of heating comprises passing a stream of heated gas past the suspended globule.
36. The method of claim 35, wherein the heated gas is nitrogen.
37. The method of claim 32, wherein the additional dilute solution added during the step of adding additional dilute solution maintains the amount of solution in the suspended globule above a prescribed minimum amount.
38. The method of claim 32, wherein the solution consists essentially of radioactive orthophosphoric acid in water.
39. The method of claim 32, wherein the suspended globule is is contact with a solid surface.
40. The method of claim 32, wherein the globule is a drop supported from a contact surface by surface tension forces during the step of evaporating solvent.
41. The method of claim 40, wherein the additional dilute solution added during the step of adding additional dilute solution maintains the amount of solution in the drop above a prescribed minimum amount.
42. The method of claim 40, wherein the step of evaporating solvent comprises energizing a heater configured to pass a stream of heated gas bast the drop.
43. The method of claim 40, wherein:
the additional dilute solution added during the step of adding additional dilute solution maintains the amount of solution in the drop above a prescribed minimum amount; and the step of evaporating solvent comprises energizing a heater configured to pass a stream of heated gas past the drop.
44. The method of claim 32, wherein:
the globule is a drop supported from a contact surface by surface tension forces during the step of evaporating solvent;
the step of adding additional dilute solution includes passing such additional dilute solution through an orifice in a container containing the dilute solution; and the additional dilute solution added during the step of adding additional dilute solution maintains the amount of solution in the drop above a prescribed minimum amount and below a prescribed maximum amount.
45. A method of forming.a concentrated mixture, of a measuring the amount concentration of a substance in a mixture with a fluid, from a comparatively dilute mixture, comprising:
suspending a drop of the dilute mixture from a contact surface by surface tension forces;
evaporating fluid from the drop until the drop has reached the prescribed concentration; and adding additional dilute mixture to the drop during the step of evaporating fluid.
46. The method of claim 45, wherein:
the substance is a solute;
the fluid is a solvent for the solute; and the mixture is a solution formed from the solute in the solvent.
47. The method of claim 46, wherein the step of evaporating fluid includes heating the drop.
48. The method of claim 46, wherein:
the step of adding additional dilute mixture includes measuring the amount of mixture in the drop to determine if it is above a prescribed minimum amount; and the additional dilute mixture added during the step of adding additional dilute mixture maintains the amount of mixture in the drop above the prescribed minimum amount.
49. The method of claim 45, wherein:
the dilute mixture is provided in a chamber of a syringe having a plunger and an orifice, the plunger being advanceable into the chamber to pass the dilute mixture through the orifice;
the step of suspending a drop includes advancing the plunger into the chamber to pass dilute mixture out of the chamber through the orifice; and the step of adding additional dilute mixture includes further advancing the plunger into the chamber to bass dilute mixture through the orifice and into the evaporating mixture; and the step of adding additional dilute mixture maintains the amount of mixture in the drop between a prescribed minimum amount and a prescribed maximum amount.
50. The method of claim 49, wherein a motor causes the plunger to be advanced in the step of suspending a drop and the step of adding additional dilute mixture.
51. The method of claim 49, wherein the syringe further contains a quantity of gas, and wherein the syringe is oriented such that gas rises to form a buffer between the plunger and the dilute mixture.
52. The method of claim 49, wherein the step of adding additional dilute mixture includes measuring the amount of mixture in the drop to determine if it is between the prescribed minimum amount and the prescribed maximum amount.
53. The method of claim 49, wherein the mixture is radioactive orthophosphoric acid in water.
54. The method of claim 49, wherein the step of evaporating fluid comprises energizing a heater configured to pass a stream of heated gas over the suspended drop.
55. The method of claim 49, wherein:
the substance is a solute;
the fluid is a solvent for the solute;
the mixture is a solution formed from the solute in the solvent.
the step of evaporating fluid comprises energizing a heater configured to pass a stream of heated gas over the suspended drop;
the plunger is advanced into the chamber by a motor during the steps of suspending a drop and adding additional dilute mixture;
the syringe further contains a quantity of gas, and wherein the syringe is oriented vertically such that gas rises to form a buffer between the plunger and the dilute mixture; and the step of adding additional dilute mixture includes measuring the amount of mixture in the drop to determine if it is between the prescribed minimum amount and the prescribed maximum amount.
56. An apparatus for forming a concentrated mixture, of a prescribed concentration of substance in a fluid, from a comparatively dilute mixture, comprising:
a syringe configured to suspend a drop of the dilute mixture after passing it through an orifice; and a measuring device configured to gauge the amount of mixture in a drop suspended by the syringe.
57. The apparatus for forming a concentrated mixture of claim 56, the syringe defining a passageway that is configured as narrow enough to substantially prevent concentration gradient diffusion from the evaporating mixture as it becomes more concentrated.
58. The apparatus for forming a concentrated mixture of claim 56, the syringe comprising:
a body having a chamber defining an opening;
a needle in communication with the opening, the needle defining the orifice;
and a plunger movable into and out of the chamber;
wherein the plunger can be advanced into the chamber to pass mixture out of the chamber and through the orifice; and wherein the plunger can be withdrawn from the chamber to draw mixture into the chamber through the orifice.
59. The apparatus for forming a concentrated mixture of claim 56, and further comprising a heater configured to evaporate the fluid from the drop.
60. The apparatus for forming a concentrated mixture of claim 56, wherein the measuring device is a laser micrometer.
61. The apparatus for forming a concentrated mixture of claim 56, and further comprising a motor configured to actuate the syringe to pass dilute mixture through the orifice.
62. The apparatus for forming a concentrated mixture of claim 61, wherein the motor actuates the syringe at a rate allowing near-continuous addition of dilute solution so as to substantially prevent concentration gradient diffusion from the evaporating mixture as it becomes more concentrated.
63. The apparatus for forming a concentrated mixture of claim 56, and further comprising a platter that's position can be both vertically and laterally adjusted.
64. The apparatus for forming a concentrated mixture of claim 56, and further comprising a platter that's position can be both vertically and laterally adjusted, the platter including one or more spring-loaded bays.
65. The apparatus for forming a concentrated mixture of claim 56, wherein the syringe is oriented such that gas in the syringe will rise to form a buffer between the plunger and the dilute mixture in the syringe.
66. The apparatus for forming a concentrated mixture of claim 56, and further comprising a computerized control system configured to control the emission of dilute mixture from the syringe in response to readings from the measurement device.
67. The apparatus for forming a concentrated mixture of claim 56, wherein the syringe includes a needle made from quartz tubing.
68. The apparatus for forming a concentrated mixture of claim 56, wherein the syringe includes a needle having a lower lip that provides a substantially flat and horizontal contact surface.
69. The apparatus for forming a concentrated mixture of claim 56, wherein the syringe includes a horizontal contact surface configured to suspend a drop produced by the syringe.
70. The apparatus for forming a concentrated mixture of claim 56, and further comprising a heater configured to evaporate fluid from a drop suspended by the syringe.
71. The apparatus for forming a concentrated mixture of claim 70, wherein the heater is a vertically oriented coil of a resistor wire configured to be energized by the application of a voltage across the wire.
72. The apparatus for forming a concentrated mixture of claim 70, wherein the heater is configured to selectively deliver heated gas through one of a plurality of ports, one of the ports being configured to form a substantially round column of heated gas, and another of the ports being configured to form band-shaped column of heated gas.
73. The apparatus for forming a concentrated mixture of claim 56, and further comprising a thin hollow tube perforated with a plurality of holes, the tube being configured to draw a drop of mixture, which has been produced by the syringe, into the tube under capillary forces.
74. The apparatus for forming a concentrated mixture of claim 56, and further comprising a heater configured to evaporate solvent from mixture suspended from the syringe, wherein the syringe comprises:
a body having a chamber defining an opening;
a needle in communication with the opening, the needle defining the orifice;
and a plunger movable into and out of the chamber;
wherein the plunger can be advanced into the chamber to pass dilute mixture out of the chamber and through the orifice;
wherein the plunger can be withdrawn from the chamber to draw dilute mixture into the chamber through the orifice; and wherein the needle includes a contact surface configured to suspend a drop produced by the syringe.
75. A method of forming a concentrated solution, of a prescribed concentration of solute in a solvent, from a comparatively dilute solution, comprising:
providing the apparatus for forming a concentrated solution of claim 74;
locating dilute solution in the chamber;
advancing the plunger into the chamber to pass the dilute solution through the orifice and form a drop of solution suspended from the contact surface, the size of the drop of solution being between a prescribed minimum size and a prescribed maximum size as measured by the measuring device;
and energizing the heater, while continuing the step of advancing the plunger, until the drop of solution has reached the prescribed concentration.
76. The method of claim 75, wherein the step of advancing the plunger is controlled by a computerized control system.
77. The method of claim 75, wherein the solution is a radioactive orthophosphoric acid in water.
78. The method of claim 75, wherein the step of locating the solution in the chamber comprises:
providing a vessel containing the dilute solution;
adjusting the relative positions of the vessel containing the dilute solution and the needle to bring the orifice into the solution;
withdrawing the plunger to draw a prescribed amount of the dilute solution into the syringe chamber; and adjusting the relative positions of the vessel containing the dilute solution and the needle to remove the orifice from the dilute solution.
79. The method of claim 78, wherein the step of locating the dilate solution in the chamber further comprises adjusting the plunger to locate a prescribed amount of air into the syringe prior to bringing the orifice into the dilute solution.
80. The method of claim 78, wherein prior to the step of locating the solution in the chamber the method further comprises:
providing a vessel containing a solvent of the type in the dilute solution;
adjusting the relative positions of the vessel of solvent and the needle to bring the orifice into the solvent;
withdrawing the plunger to draw a prescribed amount of the solvent into the syringe chamber;
adjusting the relative positions of the vessel and the needle to remove the orifice from the solvent;
advancing the plunger into the chamber to bass the solvent through the orifice and form a drop of solvent suspended from the contact surface, the size of the drop of solvent being between a prescribed minimum size and a prescribed maximum size as measured by the measuring device; and energizing the heater, while continuing the step of advancing the plunger, until the solvent has been evacuated from the chamber.
81. An apparatus for forming a concentrated solution, of a prescribed concentration of solute in a solvent, from a comparatively dilute solution, comprising:
a means for suspending a globule of the dilute solution such that solvent can be evaporated from the suspended globule; and a means for measuring the amount of solution in the globule.
82. The apparatus for forming a concentrated solution of claim 81, and further comprising a means for adding additional dilute solution to a globule of solution suspended by the means for suspending a globule.
83. The apparatus for forming a concentrated solution of claim 81, and further comprising a means for accelerating the evaporation of solvent from a globule of solution suspended by the means for suspending a globule.
84. The apparatus for forming a concentrated solution of claim 81, and further comprising:
a means for adding additional dilute solution to a globule of solution suspended by the means for suspending a globule;
a means for accelerating the evaporation of solvent from a globule of solution suspended by the means for suspending a globule; and a means for controlling the means for adding in response to readings from the means for measuring.
85. A method of precipitating substantially all of the solute from a quantity of dilute solution onto a precipitation surface, the volume of the quantity of dilute solution exceeding an amount that can be accommodated in contact with the surface without contacting other surfaces, comprising:
forming a concentrated solution from the quantify of dilute solution, the concentrated solution having substantially all of the solute that was in the dilute solution, wherein the volume of the concentrated solution does not exceed an amount that can be accommodated in contact with the precipitation surface without contacting other surfaces;
evaporating the remaining solvent from the concentrated solution to precipitate the solute onto the precipitation surface.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US09/090,891 US6391149B1 (en) | 1998-06-04 | 1998-06-04 | Method and apparatus for concentrating a solute in solution with a solvent |
| US09/090,891 | 1998-06-04 | ||
| PCT/US1999/012554 WO1999062607A1 (en) | 1998-06-04 | 1999-06-04 | Method and apparatus for concentrating a solute in solution with a solvent |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2334137A1 true CA2334137A1 (en) | 1999-12-09 |
Family
ID=22224824
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002334137A Abandoned CA2334137A1 (en) | 1998-06-04 | 1999-06-04 | Method and apparatus for concentrating a solute in solution with a solvent |
Country Status (6)
| Country | Link |
|---|---|
| US (2) | US6391149B1 (en) |
| EP (1) | EP1085928A1 (en) |
| JP (1) | JP2002516737A (en) |
| AU (1) | AU4420399A (en) |
| CA (1) | CA2334137A1 (en) |
| WO (1) | WO1999062607A1 (en) |
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-
1999
- 1999-06-04 EP EP99927253A patent/EP1085928A1/en not_active Withdrawn
- 1999-06-04 AU AU44203/99A patent/AU4420399A/en not_active Abandoned
- 1999-06-04 CA CA002334137A patent/CA2334137A1/en not_active Abandoned
- 1999-06-04 WO PCT/US1999/012554 patent/WO1999062607A1/en not_active Application Discontinuation
- 1999-06-04 JP JP2000551857A patent/JP2002516737A/en not_active Withdrawn
- 1999-09-14 US US09/395,880 patent/US6461572B1/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| US6391149B1 (en) | 2002-05-21 |
| US6461572B1 (en) | 2002-10-08 |
| EP1085928A1 (en) | 2001-03-28 |
| JP2002516737A (en) | 2002-06-11 |
| AU4420399A (en) | 1999-12-20 |
| WO1999062607A1 (en) | 1999-12-09 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |