US 3256613 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
June 21, 1966 Original Filed April 5, 1963 L. E. MOULTHROP FABRIC TREATMENT 2 Sheets-Sheet 1 INVENTOR. LEROY E. MOULTHROP ROBERT J PATCH A TTORNE Y June 21, 1966 L. E. MOULTHROP 3,256,613
FABRIC TREATMENT Original Filed April 5, 1963 2 Sheets-Sheet 2 F|G 2 TIME-MINUTES 3 4 5 6 7 8 9 IO II I2 I3 I4 I5 TIMER MOTOR FILTER PUMP MOTOR 27 EDUCTOR PUMP MOTOR 89 WASH MOTOR I5 VAPOR REMOVAL VALVE 55 FAN IO7 BY-PASS VALVE 39 FILL VALVE 3| DUMP VALVE 47 VACUUM BREAK VALVE 5I EXTRACT MOTOR l7 VAPOR RECYCLE VALVE II5 HEATER III WASH EXTRACT RECLAIM FIG.. 3
TIME MINUTES OI23456789IOIII2IEII4I5 PRESSURE INCHES OF MERCURY '6 INVENTOR. E. MOULTH ROP ROBERT J. PATCH ATTORNEY United States Patent 3,256,613 FABRIC TREATMENT Le Roy E. Moulthrop, Alhambra, Calif, assignor of twenty-five percent to Robert J. Patch, Chevy Chase, Md. Uriginal application Apr. 5, 1363, Ser. No. 270,832, new Patent No. 3,110,544, dated Nov. 12, 1963. Divided and this application Nov. 12, 1963, Ser. No. 345,829
12 Claims. (Cl. 34-15) This application is a division of copending application Serial No. 270,832, filed April 5, 1963, now Patent No. 3,110,544, November 12, 1963.
The present invention relates to cleaning methods for removing dirt such as grease, grime or stains or the like from fabric by contact with a cleaning liquid. The fabrics thus treated are comprised of animal, vegetable or certain synthetic fibers or the like, and may for example be woven, knitted, felted, and so on. The principal field of application of this invention is in the cleaning of wearing apparel.
The invention will be particularly described and illustrated in connection with dry cleaning by the use of organic liquids of the type of perchlorethylene, 1,1,2-trichloro-l,2, 2,-trifluoroethane (Freon 113), Stoddard solvent and other petroleum fraction solvents, trichlorethylene, carbon tetrachloride, and the like. It is to be expressly understood, however, that the invention in many of its aspects is not limited to dry cleaning but rather is applicable also to water washing, and that the term cleaning includes washing both with organic cleaning liquids and with inorganic cleaning liquids such as water. Similarly, the term cleaning liquid includes both organic and inorganic cleaning liquids and includes water.
The prior art cleaning methods are deficient in that they provide no satisfactory methods for drying the fabric after cleaning, and in the case of dry cleaning, no satisfactory methods for reclaiming the dry cleaning solvent. In the first place, the drying methods of the prior art are so slow that they must be practiced in separate dryers or tumblers so that the washing equipment will not be unduly tied up during the long and slow drying process. As a result, it has been necessary to provide, in addition to the machines designed to wash and spin the fabric until it is damp dry, separate dryers or reclaimers so that an economically large quantity of fabric can be handled in the generally more expensive washing and extracting apparatus. But the multiplication of the numbers of pieces of equipment thus necessary not only increases the capital investment of the professional cleaner but .also ties up expensive fioor space and necessitates a larger plant. Also, in the case of highly odorous dry cleaning solvents, the transfer of the damp fabric from the washer-extractor to the dryer or tumbler causes a great deal of malodorous vapor to be thrown out into the plant, and this in turn necessitates installation of larger capacity ventilating equipment for the plant.
In addition to their inability to dry fabric quickly, the cleaning systems of the prior art have also suffered from the disadvantage that they damage fabric by over-heating it during drying or reclamation. In the case of all types of cleaning, excessive temperature during drying of the fabric can damage the fabric by charring and in other ways; and in particular, in the case of dry cleaning with organic solvents, excessive temperature can decompose and carbonize the solvent with resultant damage not only to the fabric but also to the equipment, and in the case of halogenated hydrocarbon solvents, can give rise to the production of such poisonous gases as phosgene and/ or hydrogen fluoride.
Accordingly, still another object of the present invention is the provision of cleaning methods which will be 3,256,6l3 Patented June 21, 1966 ice so fast that they can be economically practiced in a single piece of equipment having a dry-to-dry cycle time that is shorter than any known heretofore under comparable circumstances.
The invention also contemplates the provision of cleaning methods characterized in that drying or reclamation can be carried out at a temperature low enough to avoid damage to the fabric, and in the case of dry cleaning, to avoid damage to the equipment and the production of noxious decomposition products of the solvent.
In the particular field of dry cleaning, in which the cost of the solvent makes it necessary to reuse the solvent, it is necessary to purify the solvent from time to time by passing it through a porous body of solid material in the nature of filtration and/ or adsorption means. Most commonly, these means for cleaning the solvent employ a finely divided solid material as a principal constituent of the porous body, in the-nature of filter powder which may be supported on a foraminous support that permits the passage of liquid through the support but not the pass-age of the filter powder. Filter powder for example may be diatomaceous earth or silica or the like, or, depending on the nature of the impurity to be removed from the solvent, charcoal. In any event, the finely divided material of the porous body of solid material from time to time becomes so highly charged with removed impurity that it must be removed and discarded and a fresh quantity of finely divided material added to the system. However, the spent material, or muck as it is known in this art, contains a large quantity of solvent, which must be reclaimed it the cleaning operation is to be conducted economically. In the past, it has been the practice to clean out the muck and put it in a cooker which heats the muck to the point that the solvent is distilled off. The vapor phase solvent distilled off the muck is then condensed with refrigeration and reused. Such a procedure, however, has the disadvantages that it requires special equipment and consumes a substantial quantity of power. Also, the transfer of muck to the cooker is a messy and disagreeable job. Furthermore, recovery of the solvent by use of a cooker is a long and time-consuming process.
Therefore, a further object of the present invention is the provision of dry cleaning methods characterized by simple, easy, rapid and economical reclamation of solvent from muck,
Finally, it is an object of the present invention to pro.-
vide cleaning methods that will be relatively simple, fast and inexpensive to practice, and that are well-adapted to be practiced by apparatus that is desirably compact in size, inexpensive to manufacture, easy to operate, and rugged and durable in use.
Other objects and advantages of the present invention will become apparent from a consideration of the following description, taken in connection with the accompanying drawings, in which:
FIGURE 1 is a diagrammatic view of a cleaning system according to the present invention;
FIGURE 2 is :a time sequence chart showing one embodiment of a cycle of operation of the present invention; and
FIGURE 3 is .a graph of pressure against time, showing the pressure variations to which the fabric under treatment is subjected during a cleaning cycle of the present invention according to the embodiment of FIGURE 2.
A very important feature of the invention is the drying portion of the cycle which is carried out first by heating the fabric and then by drawing a deep vacuum on it. The principalportion of the reclamation cycle follows immediately on the extraction-cycle, and is characterized by a relatively slow tumbling of the fabric in the chamber. Hot vapors, preferably laden with vapors of cleaning liquid, are circulated through the fabric to raise the fabric a to arr elevated temperature. Thereafter, a deep vacuum is drawn on the heated wet fabric, and the remaining liquid in the fabric is quickly boiled off, leaving the fabric quite dry but not too hot to be comfortably removed from the machine by hand.
The drying or reclamation process of the present invention is not be confused with drying processes in which vacuum is continuously pulled during drying and heat is continuously simultaneously applied to fabric. In such prior art drying or reclamation processes, it is necessary to apply the heat directly to the fabric, as by heating elements in contact with the fabric, in order to supply the necessary heat to the fabric. By contrast, in the present invention, in which the fabric is heated by circulation of hot vapors prior to drawing the deep vacuum, it is possible to apply as much heat as is desired to the fabric in the shortest possible time, by increasing the flow rate and/ or heat content of the hot circulating vapors, thereby to heat the fabric in the minimum time. For this purpose, the heating elements are disposed outside the chamber. When it is attempted simultaneously to heat-the fabric and draw vacuum, however, or alternately to heat the fabric and draw vacuum in a plurality of repeating cycles, it is found that the heating must be performed quite slowly so as to avoid charring the fabric or carbonizing the cleaning liquid because the heat must be applied directly to the fabric by the heating elements.
Thus, an important feature of the drying or reclamation process of the present invention is that the heat content of the fabric and its contained liquid at the higher temperature and pressure is at least about as great as the heat content of the fabric at the lower temperature and pressureto which it falls upon drawing the deep vacuum, plus the total heat of vaporization of the contained solvent at that lower temperature and pressure.
Another very important feature of the present invention is the way in which this vacuum is achieved and maintained. The kinetic energy of a relatively high pressure stream of liquid is used to withdraw a relatively low pressure stream of vapor from the cleaning chamber. This liquid is the same cleaning liquid that is used in the wash cycle. A body of cleaning liquid is maintained, and the relatively high pressure stream of liquid, with its entrained relatively low pressure stream of vapor, is directed beneath the surface of this body of liquid. Preferably, the vacuum-producing device is in the form of an eductor with the high pressure stream of liquid supplied from the body of liquid and the outlet of the eductor directed to a point below the surface of the body of liquid. Preferably, at least the outlet of the eductor is submerged in the body of cleaning liquid. This method of vacuum production is especially desirable in connection with the recovery of dry cleaning solvent vapors, because the vapors are partially condensed as they enter the low pressure inlet of the eductor and contact the higher pressure liquid stream, and are still further condensed when they emerge from the eductor and bubble up through the body of dry cleaning solvent.
In the case of dry cleaning, a further feature of the invention in connection with the production of vacuum is that the vapors withdrawn from the cleaning chamber under vacuum are partially condensed to the extent necessary to condense substantially all the water in the vapors and a portion of the dry cleaning solvent. The remaining vapors, and the condensed water and the condensed solvent, are then gravity separated in a phase separator, with the uncondensed vapor going to the low pressure inlet of the eductor, the water being discarded and the dry cleaning solvent being returned to the collected body of solvent. It has been found that in this way, the formation of wrinkles in the fabric in the course of the dry cleaning process can be entirely avoided.
Still another feature of the present invention in connection with dry cleaning is the provision of a closed circuit refrigeration cycle, characterized in that a refrigerant moves in a closed cycle alternately through compression and expansion, with the heated refrigerant following compression being used to heat vapors that are introduced into the cleaning chamber to heat the fabric, and the cooled refrigerant following expansion being used in the partial condensation of vapors from the cleaning chamber, referred to immediately above, and also to condense excess vapors vented from storage. The refrigerant following expansion is also used to refrigerate the collected body of dry cleaning solvent.
Finally, the invention is characterized by an easy method of recovering dry cleaning solvent from the muck, comprising backwashing the filter, that is, running liquid through the filter and/or adsorber units in the reverse of the normal direction so as to dislodge finely divided filter aid and/or adsorbent from the solvent cleaning equipment, followed by a vacuum reclamation of the muck thus dislodged. Preferably, the muck from which the solvent is to be reclaimed is placed in vacuum communication with the low pressure inlet of the eductor, so that no application of large quantities of extraneous heat is necessary to remove and recover the solvent from the muck in a short period of time.
One of the many embodiments of appartus by which the present invention may be practiced is shown schematically in FIGURE 1. The entire operation of the apparatus of FIGURE 1 including washing, extracting and reclaiming, is conducted in a closed cleaning chamber 9 which is a pressure-type vessel having a closure comprising a door (not shown). Preferably, the vessel is cylindrical for added strength under pressure. Cleaning chamber 9 contains a rotatable basket or cylinder 11, the outer cylindrical periphery of which is multiperforate. Chamber 9 and cylinder 11 are coaxial about a horizontal axis. Cylinder 11 rotate on its axis relative to stationary chamber 9 and contains a plurality of inwardly extending batlies 13 on the inner side of its cylindrical periphery, for the purpose of agitating the fabric and the cleaning liquid as the cylinder turns.
Means are provided for turning the cylinder at variable speeds, comprising a wash motor 15 which rotates the cylinder at a relatively low speed of rotation, for example 40 r.p.m., and an extract motor 17 that rotates the cylinder at a relatively high speed of rotation, for example, 625 r.p.m. Motor 15 operates during washing and drying, while motor 17 operates during spin drying or extraction.
In the case of a dry cleaning operation, a closed and hermetically sealed tank 19 is provided that serves to store 'a body of dry cleaning solvent 21. As used herein, the term body may include several separate sub-bodies of solvent maintained under different temperatures and/ or pressures. Solvent 21 is withdrawn from the bottom of the supply through a supply conduit 23 and passes through a filter and/or adsorber unit indicated at 25, on its way to the cleaning chamber. The solvent cleaning means indicated generally at 25 can of course take the form of plural units containing different porous solids for cleaning the liquid and preferably includes finely divided solid material in the form of filter aids or adsorbents or the like, as discussed above. However, for the sake of brevity, the solvent cleaning system will hereafter be referred to as filter 25, it being understood that this term may refer to a plurality of different units including adsorption units.
A filter pump 27 in conduit 23 urges solvent toward filter 25 under the control of a valve 29. Downstream of filter 25, a fill valve 31 regulates the flow of solvent into the cleaning chamber. A conduit 33 is provided, under control of a valve 35, that permits the flow of solvent past filter 25. A bypass conduit 37 also permits the flow of solvent from filter 25 back to tank 19. Conduit 37 is controlled by by-pass valve 39. A conduit 41 controlled by a valve 43 permits the flow of solvent back to tank 19 without going through filter 25. Ac-
cordingly, liquid from tank 19 may be sent either through filter 25 and into chamber 9, or through filter Z5 and back to tank 19, or past filter 25 into chamber 9, or past filter 25 and back to tank 19, or along several other paths, as will be apparent from FIGURE 1.
Liquid in chamber 9 can drain by gravity through 'a dump conduit 15 under control of a dump valve 4-7,
back into tank 19. To permit the pressure in chamber 9' to rise toward atmospheric, a vacuum break conduit 19 is provided that lets air into chamber 9 under control of vacuum break valve 51.
To remove vapor from th chamber so as to create a vacuum in chamber 9 and/ or to dry the fabric, a vapor removal conduit 53 is provided that communicates with a peripheral portion of chamber 9 outside cylinder 11. A pair of vapor removal valves 55 and 57 are provided in conduit 53 in parallel to each other. Valve 55 is operable between fully opened and fully closed positions, while valve 57 is more in the nature of a bleed Valve that can be set for a continuous, rather restricted flow of vapor therethrough.
The vapor leaving chamber 9 through conduit 53 passes through a condenser 59 in which it is partially condensed to the extent needed to condense substantially all of the water and a substantial proportion of the solvent in the vapor. Even if the solvent boils higher than water,- as in the case of perchlorethylene, substantially all of the water can be condensed while only partially condensing the perchlorethylene, because the quantity of water in the vapor in conduit 53 from a dry cleaning operation will be only a small fraction of the quantity of solvent in the vapor.
The partially condensed mixture enters a phase separator 61, from which uncondensed vapor phase material containing at least a substantial proportion of vapors of solvent is removed through an overhead conduit 63. The condensed water and solvent will accumulate in two layers in the bottom of the phase separator, because they have different densities and ar immiscible. In the case of a solvent such as perchlorethylene, which is substantially heavier than water, there Will be an upper layer 65 of water which may be removed through a conduit 67 and sewered, and a lower layer 69 of solvent which can be removed through conduit 71 past check valve 73, past control valve 75 and returned to tank 19. Phase separator 61 is of course shown only very schematically. It will be understood that it can take any of the usual forms for separating unmixed liquids by gravity, such as by means of a float that will sink in water and float in perchlorethylene and which regulates the operation of control valv 75, closing valve 75 at a lower position of the float and opening valve 75 at an upper position of the float, in combination with a liquid overflow for water into conduit 67.
Vapor is moved through the system by means of an eductor 77 submerged in tank 19. Eductor 77 has a high pressure inlet 79 and a low pressure inlet 81, a stream of liquid under relatively high pressure passing through the high pressure inlet serving to draw in a stream of relatively low pressure fluid through the low pressure inlet 81. The mixed stream then passes through a reduced throat 83 and emerges from an outlet 85 beneath the surface of and in contact with solvent 21. An eductor pump 87 draws liquid from beneath the surface of solvent 21 in tank 19 and forces it through high pressure inlet 79 at elevated pressure and at a substantial velocity as the high pressure stream. A motor 89 is mounted on a removable cover 91 on tank 19 and has its drive shaft 93 extending vertically down to pump 87 to drive pump 87. Conduit 63 also passes downwardly through cover 91 to the low pressur inlet of eductor 77. A coupling 95 in conduit 63 permits the portion of conduit 63 secured to cover 91 to be detached from the rest of conduit 63, so that cover 91 with motor 89 and shaft 93 and pump 37 and eductor 77 can be removedas a unit from the top of g. the tank without the need for draining the solvent from the tank. Detachable fastenings 97 remova bly secure cover 91 in hermetically sealed relationship with tank 19. Tank 19 is thus entirely sealed except for the entrance and exit conduits for liquid and vapor and drive shaft 93.
A vent conduit 99 provides egress for vapors in tank 19 above body of solvent 21. The vapors pass through a condenser 1111 in which substantially all of the solvent vapors are condensed and fall *backwardly into tank 19 in liquid phase. A check valve in the form of a butterfly valve 103 ensures that vapor. can move only one way through conduit 99, and is especially usefulin climates characterized by high humidity, so that the quantity of water added to the system will be kept to a minimum.
A vapor recycle conduit 105 is also provided, for removing vapors from chamber 9 from the outer side of cylinder 11, heating the vapors, and returning them to the interior of the chamber within cylinder 11. A filter 10:: catches and removes solid particles of dirt and lint from the vapor circulating in conduit 195. To facilitate circulation of the vapors, a fan 107 is provided in conduit 1115. Heaters 109 and 111 are also traversed in series by the vapors in conduit 1115. Heater 109 operates at a lower temperature level and heater 111 operates at a higher temperature level. Heater 111 is heated by a heating coil 113, which preferably is supplied with steam from a boiler. A vapor recycle valve 115 in a conduit 117 controllably connects'conduit 1115 with vent conduit 99 so that vapors free from water can be added ot the vapor recycling in conduit 105. Of course, instead of connecting conduit 117 to conduit 99 downstream of condenser 101, it is also possible to connect conduit 117 directly with the vapor space in tank 19.
A closed cycle refrigeration circuit 119 is also provided, comprising the usual compressor 121 and' expansion valve 123. However, the refrigeration circuit of the present invention diifers from those heretofore known in this art in that relatively warm vapor following compression in compressor 121 is utilized in a heating coil 125 that provides heat for heater 109. Heating coil 125 is thus downstream of compressor 121 and upstream of expansion valve 123. Cooling coils 127' and 129 are provided in condensers 59 and 1111, respectively, and a further cooling coil 131 is submerged in the solvent 21 in tank 19 so as to maintain the solvent temperature at a desirably low level, e.g., not more than about 70 F. or lower depending on the nature of the solvent. Cooling coils 127, 129, and 131 are shown in parallel with each other; but of course it will be realized that they can be in series or in other arrangements, depending upon the desired refrigeration duty to be borne by them. In any event, cooling coils 127, 129, and 131 are downstream of expansion valve 123 and upstream of compressor 121 in circuit 119. Of course, the temperature level of re frigeration circuit 119 may be adjusted upwardly or downwardly as desired. For example, an air cooler (not shown) for the refrigerant can be provided downstream of heating coil 125 and upstream of expansion valve 123. The refrigerant itself may be any of the usual refrigerants, such as ammonia or the halogenated hydrocarbons,
e.g., chlorodifluoromethane (Freon 22).
For reclaiming solvent from spent muck from filter 25, a filter backwash conduit 133 is provided under the control of a valve 135. Conduit 1333 delivers into a muck reclaimer 137 characterized. by a tube sheet 139 provided with a plurality of openings in each of which is set a multiperforate tubeor screen tube 141, so that backwashed muck can enter reclaimer 137 above tube sheet 139 and its liquid drain and be drawn through tubes 14.1 and out through a conduit 143 controlled by a valve 145, that communicates with conduit 63, so that the vacuum in conduit 63 induced by eductor 77 also pulls on muck reclaimer 137 when valve is closed.
A dry cleaning cycle according to the present invenvention will now be described in connection with the cycle diagram and pressure diagram of FIGURES 2 and 3. It is of course to be understood that the following cycle is merely one of many that can be devised to carry out the principles of the present invention. It is also to be understood that the pressures indicated on FIGURE 3 are only generally representative of what goes on in the cleaning chamber. It should be noted, however, that FIGURES 2 and 3 are in vertical alignment with each other, so that the events depicted in FIGURE 2 correspond to the pressures indicated directly below them in FIGURE 3. It should further be noted at the outset that the total cycle time, dry-to-dry, is only minutes, which is incredibly short for a commercial dry cleaning machine using a solvent such as perchlorethylene. This cycle time is not merely illustrative but is one of the actual very short cycle times that have been achieved by the practice of the present invention. In general, the short cycle time is achieved by the unique cleaning methods, by certain novel steps during extraction, by the unique reclamation process of the present invention, and by so arranging the cycle that a number of the events in the cycle overlap each other timewise. These various features of the invention coact together to permit an extremely short overall cycle time for the dry-to-dry process adapted to be carried out in a single machine.
Beginning at the left hand margin of FIGURE 8, therefore, it will be seen that as the cycle begins, the timer motor (not shown) is actuated which may for example turn a cam shaft (not shown) through one full revolution during the cycle. The .cam shaft may carry a series of generally circular cams (not shown) each of which corresponds to one of the timed elements of the present invention. Although the cycle of the present invention is novel in many respects, the mechanical operation of the timer motor and cam shaft, and the concept of timing the various elements each by means of its individual cam on .the cam shaft, are quite conventional and hence need not be illustrated in the drawings.
The filter pump motor 27 is shown as being in op eration throughout the cycle. Of course, it will be understood that except when flow valve 31 is open and solvent is being introduced into chamber 9, filter pump motor 27 may be operated or not as desired and as necessary to keep the solvent clean. Thus, filter pump motor 27 may be operated during the entire cycle, or during only part of the cycle, and during periods of operation that fall between cycles.
The eductor pump motor 89 operates throughout the cycle and a vacuum is constantly being drawn on conduit 63 by eductor 77. Even when vapor removal valve 55 is closed, bleed valve 57 is open, so that vacuum is continuously being drawn on chamber 9, although at a greater or lesser rate depending on whether valve 55 is open or closed, respectively. It is thus assured that the pressure in chamber 9 will never exceed atmospheric, with the result that there is a minimum opportunity for solvent vapors to escape from the system to the ambient atmosphere.
Wash motor 15 is also shown as operating throughout the cycle. Actually, wash motor 15 turns cylinder 11 at its characteristic slow speed only during the first few minutes of the cycle, generally corresponding to the wash cycle, and during the last half of the cycle generally corresponding to reclamation for drying. Extract motor 17 spins the cylinder at relatively high speed during the intervening extract cycle, but it is easier to leave wash motor 15 running during extraction, disconnecting it by means of a clutch, than to turn it on and off, although of course wash motor 15 may, if desired be shut off during the extract cycle corresponding to the time between the four and seven minute intervals.
As the cycle starts, therefore, vapor removal valve 55 is open, fan 107 is operating and by-pass valve 39 is open. Fill valve 31 is closed, as are also dump valve 47 and vacuum break valve 51. This means that no solvent is entering chamber 9, but that fan 107 is circulating air at high speed through conduit and filter 106 and through the chamber while cylinder 11 slowly turns and eductor 77 draws a fairly deep vacuum in chamber 9, as represented by the sharply descending line on FIGURE 9 during the first 45 seconds or so of the first minute.
At 45 seconds, vapor removal valve 55 closes, fan 107 shuts off, by-pass valve 39 closes and fill valve 31 opens. Solvent now begins to enter and partially fill the chamber and contact and immerse the fabric.
From 45 seconds to about a minute and three-quarters, the solvent continues to enter chamber 9 until solvent fills about half the chamber or somewhat less. Depending upon the rate of solvent entry and the setting of bleed valve 57, the pressure in the chamber may or may not rise from the fairly deep vacuum of 45 seconds. In the illustrated embodiment, FIGURE 3 indicates a pressure rise due to solvent entering chamber 9 faster than vapor is bled through valve 57. In any event, at a minute and three-quarters, dump valve 47 is opened to drain the solvent through dump conduit 45. The draining of the solvent would be very slow were it not for the fact that at the same time, vacuum break valve 51 opens to let air enter through conduit 49, so that the pressure in chamber 9 rises rapidly toward atmospheric and solvent dumps quickly through conduit 45 into tank 19. After about 10 seconds, vacuum break valve 51 closes, whereupon the draining through dump valve 47 is greatly reduced or stopped altogether. However, fill valve 31 remains open, so that solvent is-moving back into chamber 9 tending to replenish that which was dumped when vacuum break valve 51 was briefly open. At the same time, however, a vacuum is being drawn through bleed valve 57, and at this time, vapor is being withdrawn through bleed valve 57 at a faster rate than solvent is entering the chamber through conduit 23. As a result, the pressure in the chamber falls off somewhat, as is indicated by the descending line immediately following the two-minute interval in FIGURE 3. Shortly after two minutes, the vacuum break valve 51 opens again, and dump valve 47 remains open, so that even though the solvent level rapidly falls, air rushes in still faster, which accounts for the rise in chamber pressure between two minutes up until about three minutes in FIGURE 3. At almost three minutes, the vacuum break valve closes and the fill valve 31 remains open, which causes the pressure to again fall because vapor is being withdrawn through bleed valve 57 faster than solvent is entering through fill valve 31, until a low pressure is reached at about 15 seconds after three minutes, as shown in FIGURE 3. During this portion of the cycle, dump valve 47 is closed for this final filling of the chamber. At the end of this final filling, fill valve 31 closes and by-pass valve 39 opens, so that thereafter throughout the cycle the solvent will simply be recycled to the tank 19. After this final fill, dump valve 47 and vacuum break valve 51 both open, at about three minutes and 15 seconds, whereupon the pressure rapidly rises as is shown by the ascending line after the three minute interval and up to about the four minute interval, which is the end of the wash cycle.
At four minutes, the extract motor 17 starts to operate and the cylinder 11 starts to spin at relatively high velocity. It should be noted that cylinder 11 is provided with bafiles 13, and also that the fabric within cylinder 11 is never uniformly arranged about the periphery of the cylinder. As a result, cylinder 11 presents a somewhat uneven interior, and as the cylinder with its uneven interior peripheral portion spins at high speed, it has the ability to act as the rotor of a centrifugal fan. A very unique feature of the present invention is that the potentiality of the cylinder to act as the rotor of a centrifugal fan is utilized by withdrawing vapor through conduit 105 from the periphery of chamber 9, circulating it through heaters 169 and 111, and return it to the interior of 9 chamber 9 within cylinder 11. Circulation through conduit 105 is thus assured by the centrifugal fan action of cylinder 11 during extraction. At the same time, refrigeration circuit 119 is in operation and coil 125 is serving to heat heater 109, so that the vapors circulating through conduit 105 are heated and tend to raise the temperature of the fabric during extraction.
After extraction is partly over, heater 111 with its stem coil 113 is actuated to impart additional heat to.
the vapor circulating in conduit 105. At the same time, fan 107 is actuated to increase the circulation and also increase the heat transfer to the fabric. As the fabric increases in temperature, the amount of solvent leaving it in vapor phase increases, so that vapor removal valve 55 is also opened, whereupon the withdrawal of vaporized solvent from chamber 9 through conduit 53 is greatly increased. These vapors withdrawn through conduit 53 are, as mentioned above, partially condensed in condenser 59, then further condensed by contact with the relatively high pressure stream of liquid solvent as they enter eductor 77 through the low pressure inlet, still further condensed when the remainder of the vapor emerges from outlet 85 of eductor 77 and bubbles through the relatively cool solvent 21, and then finally substantially completely condensed as they pass out through vent conduit 99 through condenser 101.
Heating the fabric preparatory to reclamation of the solvent has thus begun at the very onset of extraction and is increased toward the end of extraction. The reclamation and extraction cycles thus overlap each other in the present invention, and this is another example of doubling up the events of the cycle of the present invention so as to reduce overall cycle time.
At the seven minute interval, extraction is over and cylinder 11 returns to its previous relatively slow speed of rotation so that the damp dried fabric is tumbled in the cylinder. However, fan 107 continues to operate, and hot solvent vapors continue to recycle at high velocity through conduit 105. The build-up of excessive solvent vapor in the cleaning chamber is prevented by continu ous vapor removal through valve 55. Heat continues to be added to the fabric by heat exchange in heaters 109 and 111. The temperature and heat content of the wet fabric is rapidly rising during the first four and one-half minutes of reclamation, up to about the 11 /2 minute interval.
At the 11 /2 minute interval, vapor recycle valve 115 closes. This means that the only communication between the cleaning chamber and tank 19 is now through the inlet 31 of eductor 77. As a result, a deep vacuum is again very swiftly drawn in chamber 9, for the apparatus is now in the same condition as during the first 45 seconds of the cycle; however, the fabric is now damp dry and quite hot. As the pressure drops to a fairly deep vacuum, the boiling point of the solvent rapidly falls. The remaining solvent entirely boils off, leaving the fabric dry. The boil-off is quite rapid, and this final drying need proceed only for a short time. It is important, however, that prior to drawing the vacuum, the temperature of the damp dry fabric be sufiiciently high that its heat content will be at least about as great as the heat content of the dry fabric after drawing the vacuum plus the total heat of vaporization of the solvent at the conditions of temperature and pressure under which vaporization occurred. In this condition, it will be remembered that the temperature of the fabric and solvent will drop during boil-off, and that the heat of vaporization of the solvent will in general vary inversely as the temperature. The temperature to which the fabric and solvent drop during boil-off should of course be suificiently high that the solvent boils off and the fabric is left dry.
When this specification and the claims speak of the heat content of the hot damp fabric at the higher temperature and pressure being about equal to at least the heat content of the fabric plus the total heat of vaporiza- 1 11 tion at the lower temperature and pressure, it is to be remembered that heater 111 continues in operation for a short time after the deep vacuum is drawn, so that heat is still added to the fabric for a short time after the deep vacuum begins to be drawn. Therefore, the term about is to be construed with this proviso in mind.
The precise temperature conditions at the higher and' lower temperatures cannot be set forth with accuracy but must be determined having regard for the quantity of fabric, the nature of the dry cleaning solvent, the heating equipment, and other factors well known to persons skilled in this art. The temperature of the fabric cannot be meas ured with accuracy and therefore cannot be set forthin this specification. Suffice it to say, however, that the necessary quantities of heat to be added to and removed from the fabric so as to arrive at a dry fabric at the lower temperature and pressure after drawing the deep vacuum can readily be ascertained by those having ordinary skill in this art, having regard for the vapor pressure and latent heat of vaporization curves of the particular solvent in question and the specific heats of the fabric undergoing cleaning.
In the cycle of the present invention, therefore, the rapid boil-off of the solvent depends upon adding sub stantially all of the heat'necessary to achieve that boil-off to the damp dry fabric prior to drawing the deep vacuum. This heat addition is effected by rapid circulation of hot solvent vapors through the tumbling fabric. The addition of solvent to what would otherwise be hot air increases the heat content of this rapidly recirculating vapor, and the quantity of heat to be added in this manner can be increased as much as desired by increasing the rate of recirculation of the hot vapors. Moreover, damage to the fabric is avoided because the heat exchange between the heating elements and the fabric is indirect. The heaters are outside the chamber and are not in direct contact with the fabric. In this connection, the use of steam heat in heater 111 for the high temperature level heater is preferred, because the pressure of the steam can be so controlled that its temperature will never rise'high enough to cause an organic cleaning solvent to carbonize or form toxic decomposition products.
At the end of vacuum reclamation, vacuum break valve 51 opens again to let in sufficient air to raise the pressure of the chamber to atmospheric. Fan 107 continues to operate and the cylinder continues to turn during these last 45 seconds or so of the cycle, and vapor removal valve 55 remains open with eductor 77 operating, so that solvent vapor within the chamber tends to be progressively displaced and replaced by air entering the chamber through vacuum break conduit 49'at the very end of the cycle. At the same time, the fabric is aired out by the tumbling and the fan action in the presence of fresh air, so that solvent vapors and odors are to a large extent removed from the fabric before it is removed from the cleaning chamber.
With the return of the chamber to atmospheric pressure, the door can be opened and the dry fabric removed. The fabric will then be found to be at a temperature such that it can be handled comfortably, for the relatively high heat of the fabric just before the deep vacuum was drawn during reclamation was reduced by the boiling away of the solvent at the end of reclamation.
From time to time, the filter powder or other finely divided solid solvent cleaning agent on filter 25 will become spent and must be reclaimed to recover its solvent content. To do this, it is necessary only to open valves 35, 135, and and close valves" 29, 31, 39, and 43, with pump 27 operating, so that solvent enters filter 25 from the opposite direction and reverse washes or back Washes filter 25, so that the muck is stripped from filter 25 and passes through conduit 133 in a slurry and enters muck reclaimer 137 where it surrounds screen tubes 14-1. Eductor 77 is operating to draw vacuum through conduit 14.3 with valve 145 open, and the solvent is rapidly drained off through tubes 141 and conduit 143 and is returned to tank 19. Thereafter, valve 135 is closed, whereupon a relatively deep vacuum is drawn in reclaimer 137. After reclamation, the dry muck can be removed from reclaimer 137 through a door (not shown).
Although the solvent in the muck does not necessarily boil during reclamation in 137, nevertheless, the rate of evaporation of the solvent from the muck at ambient temperature is greatly increased. Moreover, with valve 135 closed, a vacuum can be drawn in reclaimer 137 with the rest of the system in operation. The evaporation of the solvent from the muck in reclaimer 137 under vacuum does not substantially affect the operation of any other portion of the system, so that muck can be transferred to reclaimer 137 and left there to be dried under vacuum While the system of the present invention is otherwise in normal operation. This is in sharp contrast to the usual muck reclaimers, which in the first place have no such provision for convenient transfer to the reclaimer as in the present invention, and in the second place use steam or other heat to try to boil off the solvent at elevated temperature. Such elevated temperature muck reclaimers or cookers, moreover, have the great disadvantage that they are slow, consume a great deal of power, and require a great deal of extra equipment. The reclamation method of the present invention, however, obviously requires only a minimum of additional equipment, and is fast and inexpensive to practice.
From a consideration of the foregoing disclosure, therefore, it will be evident that all of the initially recited objects of the present invention have been achieved.
Although the present invention has been described and illustrated in connection with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit of the invention, as those skilled in this art will readily understand. In particular, there are many alternative Ways of producing pressure change in the cleaning chamber during the washing cycle. In the illustrated embodiment, the pressure rises upon discharge of the solvent and falls upon reintroduction of rinse solvent; but the reverse arrangement can be effected, in which case the dump conduit 45 and dump valve 47 are made sufiiciently large that a substantial dumping flow rate of solvent can be achieved even with vacuum break valve 51 closed, so that the dumping of solvent would drop the pressure in the chamber and the refilling with solvent would again raise the pressure. These and many other modifications and variations are considered to be within the purview and scope of the present invention as defined by the appended claims.
What is claimed is:
1. A method of removing dry cleaning solvent from fabric in a chamber, comprising establishing a body of dry cleaning solvent outside a chamber containing fabric wet with dry cleaning solvent, establishing a relatively high pressure stream of said dry cleaning solvent in liquid phase, and applying the kinetic energy of said stream to solvent vapors from the interior of said chamber to force said solvent vapors beneath the surface of and in contact with said body of solvent thereby to condense vapors phase dry cleaning solvent.
2. A method as claimed in claim 1, and condensing from the vapor from the interior of said chamber solvent and water emanating from the chamber and separating the condensed water and solvent from each other prior to introduction of the vapor into contact with said body of solvent.
3. A method as claimed in claim 1, and condensing from the vapor from the interior of said chamber solvent and water emanating from the chamber and separating the condensed water and solvent from each other prior to application of said kinetic energy to the vapor.
4. A method as claimed in claim 1, and passing the solvent in liquid phase through a porous body of solid material to clean the solvent, removing solvent from the solid material in vapor phase, and introducing the latter vapor-phase material beneath the surface of and in contact with said body of solvent.
5. A method as claimed in claim 1, and passing the solvent in liquid phase through a porous body of solid material to clean the solvent, and removing solvent from the solid material by placing the solid material in fluid communication with the low pressure region resulting from said application of kinetic energy.
6. A method of removing dry cleaning solvent from fabric, comprising evaporating solvent from the fabric, condensing the evaporated solvent, collecting the condensed solvent in a body, establishing a refrigeration cycle in which a refrigerant is compressed and expanded in a closed fluid circuit, cooling the body of solvent by heat exchange with the refrigerant after expansion, and warming the fabric to evaporate thesolvent by heat exchange with the refrigerant after compression.
7. A method of handling dry cleaning solvent, comprising removing dry cleaning solvent from fabric wet with dry cleaning solvent, collecting the removed solvent in a body, establishing a refrigeration cycle in which a refrigerant is compressed and expanded in a closed fluid circuit, cooling the body of solvent by heat exchange with the refrigerant after expansion, and warming the fabric by heat exchange with the refrigerant after compression.
8. A method of handling cleaning liquid, comprising removing cleaning liquid from fabric wet with cleaning liquid, collecting the removed liquid in a body, establishing a refrigeration cycle in which a refrigerant is compressed and expanded in a closed fluid circuit, cooling the body of liquid by heat exchange with the refrigerant after expansion, and warming the fabric by heat exchange with the refrigerant after compression.
9. A method of removing cleaning liquid from fabric, comprising establishing a quantity of fabric Wet with a cleaning liquid in a chamber at a first pressure, heating the wet fabric to an elevated first temperature, and reducing the pressure on the wet fabric to a second pressure thereby to boil off the liquid and reduce the temperature of the fabric to a second temperature, said first and second pressures and said first and second temperatures being so related that the heat content of the fabric and the liquid at the first temperature and pressure are at least about as great as the heat content of the fabric plus the total heat of vaporization of the liquid at the second temperature and pressure.
10. A method of removing dry cleaning solvent from fabric, comprising heating the fabric to remove dry cleaning solvent from the fabric by evaporation at elevated temperature, establishing a refrigeration cycle in which a refrigerant is compressed and expanded in a closed fluid circuit, warming the fabric by heat exchange with the refrigerant after compression, and cooling and condensing evaporated solvent by heat exchange with the refrigerant after expansion.
11. A method of removing dry cleaning solvent from fabric, comprising heating the fabric to remove dry cleaning solvent from the fabric by evaporation at elevated temperature, cooling and condensing evaporated solvent and collecting the condensed solvent in a body, establishing a refrigeration cycle in which a refrigerant is compressed and expanded in a closed fluid circuit, warming the fabric by heat exchange with the refrigerant after compression, and cooling and condensing solvent vapors emerging from above said body of solvent by heat exchange with the refrigerant after expansion.
12. A method of removing dry cleaning solvent from fabric in a chamber, comprising establishing a body of dry cleaning solvent outside a chamber containing fabric wet with dry cleaning solvent and water, removing vapor from the interior of said chamber, condensing from said removed vapor solvent and water and separating the condensed water and solvent and the uncondensed vapor from each other, combining said separated solvent with said References Cited by the Examiner UNITED STATES PATENTS 1,775,699 9/1930 Silver 34-77 1,947,174 2/1934 Sando 34-77 1,960,914 5/1934 McCoy -2 261-77 1,983,422 12/1934 Voorhees 122-479 10 Sando 34-77 Johnson 34-77 McDonald 34-73 Cohen 34-37 Smith 34-77 Williams 34-76 Severance 3477 WILLIAM J. WYE, Primary Examiner.