US 3646960 A
An arrangement for injecting a defined volume of a first fluid into a second streaming fluid is provided. The injection is carried out by separating two normally sealed tube sections through which the streaming fluid passes. The fluid to be injected is supplied to a chamber which surrounds the junction of the sections. An overpressure is obtained in the chamber, the overpressure generating an axial force which separates the sections and opens a passage through which the fluid is injected.
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Description (OCR text may contain errors)
United States Patent Jidling et al.  Mar. 7, 1972  INJECTION AND DOSING  References Cited ARRANGEMENTS UNITED STATES PATENTS [721 3 Spams; 3,443,570 5/1969 King et al ..l37/I va'lmgby bah Swede 3,517,69l 6/1970 Kilgore ..l37/565 x  Assignee: LKB-Produkter AB, Bromma, Sweden 3,524,366 8/1970 Hrdina 137/! [221 Primary Examiner-William R. Cline [2!] App]. No.: 23,716 Attorney-ChristenrSzSabol  Foreign Application Priority Data  ABS CT An arrangement for injecting a defined volume of a first fluid Apr. 25, I969 Sweden ..5949/69 mm a Second Streaming fluid is provided. The injection is ried out by separating two normally sealed tube sections  U.S.Cl ..l37/565, 12%71//68Ol2,2266ll//l3, through which the streaming fluid passes- The fluid m be  Int Cl 6 loo jected is supplied to a chamber which surrounds the junction  Field 417/65 of the sections. An overpressure is obtained in the chamber,
the overpressure generating an axial force which separates the sections and opens a passage through which the fluid is injected.
6 Claims, 1 Drawing Figure INJECTION AND DOSING ARRANGEMENTS The present invention refers to an arrangement for injecting one fluid into another, especially for injecting a gas into a liquid.
It is sometimes desirable in certain chemical applications to insert a defined volume of gas bubbles into a streaming liquid. One reason for carrying out such an injection is to separate a liquid streaming in a tube into parts or fractions of a determined length for sampling or the like. In other applications it might be desirable to supply agas for reaction with streaming liquid.
In the arrangements for dosing or injection of a gas into a liquid previously used, the supply of gas is carried out by supplying a number of bubbles of varying size. This method is of course not satisfactory especially not at such applications where by dosing of a gas one wants to cut ofi a streaming liquid at definite intervals. The difl'iculty at dosing consists in that the liquid in which the injection is to take place moves with a higher or lower velocity in consequence of which the supplied gas is disintegrated into fragments or bubbles. It might of course also be desirable to insert a liquid into a streaming gas and it is of course also at such applications necessary to avoid that the supplied liquid is disintegrated into small framents by the streaming gas.
An object of the present invention is to provide an arrangement by means of which an injection into a streaming fluid can take place in a controllable way both concerning the injected amount and the supplying without the supplied fluid being disintegrated into fragments.
The arrangement according to the invention for injecting a first fluid into a second streaming fluid, preferably a gas into a liquid, comprises a tube in which the second fluid is streaming, conducting means for transferring the first fluid to the injeclion point and in connection with this point a passage through which the first fluid can be transferred into the tube. The arrangement according to the invention is characterized by a chamber which surrounds the tube at the injection point at which the conducting means terminate, and that it is provided with pressure-generating means which are arranged to supply said first fluid to the chamber via the conducting means and generate an overpressure in the chamber which pressure opens the passage, which surrounds said streaming second fluid so that a determined amount of said first fluid is supplied into said second streaming fluid.
By means of the surrounding passage of the tube in which the second fluid is streaming an injection of a continuous quantity of the first fluid into the second streaming fluid is obtained without the injected material being disintegrated into small fragments of the streaming fluid.
According to a preferred embodiment of the invention the tube consists of two parts, which are sealed to each other, one part being axially movable so as to make it possible to form said passage. Other characteristics of the preferred embodiment of the arrangement according to the invention will appear from the enclosed claims.
The arrangement will be described in detail with reference to the enclosed drawings which partly sectionally shows a preferred embodiment of the arrangement according to the present in vention.
The arrangement shown in the drawing is intended to be used for injection of air into the streaming liquid. The apparatus consists of a housing 1 made from light metal, for instance aluminumv The housing is provided with a recess 2 and a channel 4 which terminates in the recess 2. The recess comprises a resiliently suspended apparatus 3 which in turn suspends the tube in which the fluid is streaming, the tube consisting of two parts, a stationary part 5 and a movable part 7. These two parts 5 and 7 together form a central passage 6, through which the fluid into which air is to be injected streams upwards, as indicated by the arrow at the bottom of the part 7.
The apparatus 3 consists substantially of three parts; a lower casing [7, an upper socket l9 and a flanged casing 21 that sur rounds the socket and the top ofthe casing I7.
The movable tube 7 is at the top provided with an extended part 9, which in turn is terminated by'a surrounding flange l I. At the top of the tube 7 a circular thin-walled collar 13 is ar ranged, which collar along its periphery is clamped between the casing 17 and the socket l9 and is sealed by an O-seal20.
The stationary tube 5 is mounted in the socket 19 which is arranged within the flanged casing 21 and sealed against the flangeby means of an O-seal 22. The sealed flange is by means of rubber seals 23 resiliently suspended in the recess 2 of the housing 1 and is provided with a surrounding slot 28.The purpose of this slot will appear from the description below.
The movable tube 7 is attached to the stationary tube 5 by means of a spring 15, whichis clamped to the lowerpart of the flange ll and also clamped to a plate 18 attached to the lower casing'l7. The plate 18 can by means of screwing be moved upward or downward in the casing 17 so as to regulate the pressure of the spring 15. The collar I'Jtogether with lower part of the socket 19 form the walls of chamber H which surrounds the junction between the stationary tube 5 and the movable tube 7.
The chamber I4 is connected to atmosphere via a channel 25 the purpose of which will be explained below. The socket 19 is provided with several channels -26 by means of which a connection of the chamber 14 and the surrounding slot 28 is obtained, so as to connect the chamber 14 to atmosphere via the channel 25.
The top of the housing 1 is provided with a recess 44 in which a screw 46 is arranged, the lower part of the screw being provided with an O-seal 47 for sealing against the surrounding wall of the recess. The screw 46 forms the upper wall of a cavity 49, the cavity being connected to the channel 25 via a channel 51. By turning the screw 46 this is raised or lowered in the recess 44.
The left part of the housing 1 is provided with a projecting part 27 which suspends a membrane 29. This membrane is clamped to the part 27 by means of two rings 31 and 33 respectively. The membrane 29 is arranged on the projecting part 27 where the channel 25 terminates. The center of the membrane is provided with an opening 35 through which a connection between the channel 25 and the surrounding atmosphere is established.
At the very left of the drawing the pressure-generating means are shown. These means consist of an electromagnetically controlled plunger 39. The plunger 39 is connected to a through shaft 4! which comprises an armature disposed within the electromagnet 37 so as to obtain an axial moving of the shaft 41 when a current passes through the electromagnet 37, a moving of the axis implying that a spring 43 mounted between a flange 4S and the electromagnet 37 is extended. The part of the plunger 39 which is turned to the membrane 29 is provided with a rubber film 36, for instance made from the same material as the membrane 29.
The function of the above-defined arrangement will now be described. The fluid into which air is to be supplied is streaming upwards through the passage 6 within the tube 5, 7, the direction of the flow being as indicated by the arrow. When air is to be supplied to the streaming fluid the arrangement is in the state shown in the figure. When a current is supplied to the electromagnet 37 the plunger 39 is moved to the right so as to seal the rubber film 39 against the membrane 29 thus sealing the opening 35. When the plunger 39 moves further to the right air will be pressed through the channel 25 to the cavity 28 and via the channel 26 into the chamber 14. When the pressure in the chamber l4 has reached a certain value the spring 15 will be compressed and the tube 7 moves downwards. This implies that a surrounding slot between the endings of the tubes 5 and 7 will be formed, air being impressed through the slot because of the pressure in the chamber 14. The air forms a bubble in the passage 6 which bubble completely cuts off the streaming fluid. When air is injected in the streaming fluid the pressure in the chamber 14 will be reduced which in turn implies that the top of the tube 7 is moved upwards so as to seal against the lower end of the tube 5. When the current through the magnet 37 is switched off, the plunger 39 will return to the position shown in the figure and the above-described procedure can be repeated.
The magnet 37 may preferably be controlled electronically so as to obtain bubbles of a predetermined length and having a predetermined distance from each other. If the stationary tube 5 is made from for instance glass it is possible to control the current through the magnet 37 by detecting alterations of the refraction index of the fluid. it is for instance possible to locate two indication devices at the tube 5, the devices being located with a definite distance between them, the distance being equal to the length of the gas bubble and the first of the devices being located at a desired distance from the junction between the tubes 5 and 7. When the front of the streaming fluid reaches the first indication device a current is supplied to the magnet 37, this implying that air is impressed into the fluid as described above. When the front of the fluid reaches the second indication device the current is switched off so as to obtain a bubble of a predetennined size in the streaming fluid. This procedure might then be repeated an arbitrary number of times so as to form a desired number of fluid columns of desired length.
The purpose of the channels 26 in the socket I9 is to provide an even pressure in the chamber 14, the number of channels being two or more. Thus it might be preferable to have three channels 26, which are off set I20 in relation to each other.
By using the above-described arrangement the amount of air can be varied in different ways. By turning the plate 18 the plate can be moved upward or downward thus changing the pressure of the spring and the opening pressure of the chamber l4. By changing the position of the screw 46 in the recess 44 the cavity 49 and thus the size of the bubbles might be varied.
The above-described arrangement might of course be modified within the scope of the invention. The essential feature of the invention is that the injected fluid is supplied to the periphery of the streaming fluid so as to cut off this fluid by one single continuous amount of the injected fluid. The pressure-generating member might of course be of various kinds and the invention is not restricted to the described electromagnet controlling. it is for instance also possible to use a displacement pump. The movable tube 7 might of course be made from Teflon, as this material seals well to glass.
1. Apparatus for injecting a first fluid into the stream of a second fluid comprising two axially aligned tubes for confining a stream of said second fluid, a chamber having at least one flexible wall, means to position the adjacent ends of said tubes within said chamber and to connect one of the tubes with said flexible wall for axial movement toward and away from the other tube, biasing means to urge the adjacent ends of said tubes into abutting engagement with each other, means to introduce said first fluid into said chamber in contact with said flexible wall under pressure sufficient to overcome said biasing means to move said one tube axially away from the other tube to introduce said first fluid into the stream of said second fluid.
2. The invention defined in claim I, wherein the other of said tubes is stationary, and said biasing means comprises spring means.
3. The invention defined in claim 2, wherein said flexible wall comprises an annular collar surrounding said one tube and another wall of said chamber is disposed opposite to said collar, the end of the stationary tube being disposed in said another wall of the chamber.
4. The invention defined in claim 1, wherein said means to introduce said first fluid includes a channel having one end in communication with the interior of said chamber, the other end of said channel being in communication with an opening and means to confine a predetermined amount of said first fluid in said channel and opening, said last means including flexible membrane means disposed across said opening and plunger means movable into engagement with the mem rane means to force said first fluid into said chamber.
5. The invention defined in claim 4, wherein said flexible membrane means is provided with a central aperture, and said aperture is closed by said plunger means when in engagement with the membrane means.
6. The invention defined in claim 4, wherein said means to introduce said first fluid also includes a second chamber in communication with said channel, and means to vary the volume of said second chamber to vary the pressure and amount of the first fluid introduced into the stream of the second fluid.