US3617208A

US3617208A - Methods and apparatus for cleaning textiles

Info

Publication number: US3617208A
Application number: US877762A
Authority: US
Inventors: Manfred Rolf Burger
Original assignee: Individual
Current assignee: Individual
Priority date: 1968-11-25
Filing date: 1969-11-18
Publication date: 1971-11-02
Anticipated expiration: 1988-11-02
Also published as: FR2024154A2; GB1250480A; FR2024154B2; GB1296704A; DE1957178A1

Abstract

Low-boiling solvent is circulated in a dry cleaning apparatus during cleaning from a cleaning tank through a filter to a storage tank and back to the cleaning tank. Mechanical refrigeration units control the temperature and pressure in the apparatus by drawing solvent vapors from the tanks and returning cold liquid solvent to the storage tank. One of the units also condenses the solvent vapors driven out of the cleaned objects by heating after the cleaning step, and makes a vent unnecessary.

Description

United States Patent Inventor Appl. No.

Priorities Manfred Rolf Burger Munich, Germany Nov. 18, 1969 Nov. 2, 1971 Daniel Stephen Delany London, England a part interest Nov. 25, 1968 Great Britain July 22, 1969, Great Britain, No. 36,879/69 Continuation-impart of application Ser. No. 125,293, Apr. 30, 1968, now abandoned.

METHODS AND APPARATUS FOR CLEANING TEXTILES 7 Claims, 2 Drawing Figs.

US. Cl

"511 'inTIEI D061 1/02 [50] Field of Search 8/142; 68/ l 8 A, 18 R [56] References Cited UNITED STATES PATENTS 3,122,908 3/1964 Stanulis et al 68/18 A 3,426,446 2/1969 Lotzsch 68/78 R Primary Examiner-Mayer Weinblatt Attorney-Low & Berman ABSTRACT: Low-boiling solvent is circulated in a dry cleaning apparatus during cleaning from a cleaning tank through a filter to a storage tank and back to the cleaning tank. Mechanical refrigeration units control the temperature and pressure in the apparatus by drawing solvent vapors from the tanks and returning cold liquid solvent to the storage tank. One of the units also condenses the solvent vapors driven out of the cleaned objects by heating after the cleaning step, and

makes a vent unnecessary.

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By :mww HO/M H GEN 75 METHODS AND APPARATUS FOR CLEANING TEXTILES CROSS-REFERENCE TO RELATED APPLICATION Ser. No. 725,293,filed Apr. 30, 1968.

BACKGROUND OF THE INVENTION This invention relates to drycleaning apparatus and its operation, and particularly to the solvent circuit and solvent handling in such a plant. It is concerned with facilitating the use of drycleaning solvents which have low boiling points, in particular monofluorotrichloromethane (CFCl which boils at 23 C. The present invention is applicable not only to clothes but to textiles in general.

In conventional drycleaning plants, the objects to, be cleaned, typically garments of textile material, are mechanically agitated in a cleaning tank while at least partly immersed in a solvent. When an adequate amount of impurities has been removed from the garments, the solvent is largely drained off, and the contents of the tank, mainly consisting of the garv ments, are heated to evaporate residual solvent. The solvent vapor is removed from the tank, a portion of the solvent is recovered in a heat exchanger, and the remainder is vented to the atmosphere.

The temperature to which the contents of the cleaning tank can be heated is limited by the fact that excessive evaporation of water from the garments can cause harshness and mustbe avoided. The cleaning tank ultimately is filled with a mixture of air ans solvent vapor saturated at the prevailing temperature. This vapor is not readily recovered. If the boiling point of the solvent is low and the solvent is not recovered, the resulting solvent loss significantly affects the economics of the process. The known equipment necessary for recovering the solvent present in vapor form is bulky and expensive to build and operate.

In British Pat. No. 1,079 ,703 published in 1967, there is a proposal to use monctluorotrichloromethane as a drycleaning;

solvent. The vapor is cooled at atmospheric pressure by a circulating liquid, which is in turn cooled by a refrigerator. This involves a complex apparatus with considerable problems of formation of ice both inside and outside some of the heat exchange surfaces.

in Dutch Pat. Application No. 6,6l6,930, published in 1967 there is a proposal to use monofluorotrichloromethane as a drycleaning solvent, but this proposal cannot be operative, as it supposes that a mixture of air and solvent vapor can be split into its constituent parts by the mere action of gravity in a separating chamber.

An object of the present invention is a modification of the conventional drycleaning plant and of its mode of operation. which reduces solvent looses to almost zero in a simple manner and with compact equipment which can be built and operated at low cost.

A concomitant object is a general improvement in drycleaning plants which permits the use of solvents whose boiling point is only slightly above or even below the ambient temperature without requiring complex and costly thermal insulation or cooling jackets.

SUMMARYOF THE INVENTION With these and other objects in view, as will hereinafter become apparent, the invention provides a drycleaning plant with at least one mechanical refrigeration unit whose compressor intake communicates with the solvent circuit of the plant. the circuit including the aforementioned cleaning tank and a storage tank, and apparatus for transferring solvent between the tanks. A cooling means of the unit communicates with the compressor to receive compressed fluid and for cooling the samc,.and an expansion nozzle connected to the cooling means communicates with the solvent circuit for releasing the compressed and cooled fluid into the circuit.

The briefly described apparatus is effective in controlling the solvent temperature and its vapor pressure in the solvent circuit, and thus permits the use of low-boiling solvents. It is particularly useful in removing solvent vapor from the cleaning tank after residual solvent in the objects to be cleaned has been converted to vapor by heating the contents of the tank. The vapor is compressed until its temperature is sufficiently increased, cooled while its pressure is maintained, and the pressure is then released to cause at least partial condensation the vapor to liquid. The liquid then is removed readily.

If the liquid discharged from the mechanical refrigeration unit has a temperature substantially lower than that of the heated contents of the tank and the vapor in the tank is contacted with the cold liquid, the partial pressure of the vapor in the tank is determined by the temperature of the liquid solvent, and can be made as low as desired by suitably dimensioning and operating the refrigeration unit.

More specifically the essential features of the present invention are that the vapor, which is compressed and thereby heated, is then cooled but not condensed in a heat exchanger, and then expanded, and thereby the vapor chills itself below its condensation temperature, and the resultant liquid solvent is collected.

In practice, air is also present in the chamber, and moisture is present both in the air and in the textiles. Air and moisture enter the compressor in a mixture with the solvent vapor. It is therefore the mixture which is chilled by expansion, and the presence of the air, which expands, means that the majority of the solvent becomes liquid. The air is separated from the liquid solvent at the point of lowest temperature in the system, so that it carries with it only a very small amount of solvent as vapor. Hence the amount of solvent lost in escaping air each time a door is opened to permit a load of textiles to be removed from the chamber is very small, and the main advantage of this invention is the low consumption of solvent.

Preferably the heat exchanger is cooled by atmospheric air. The moisture may freeze at the point in the circuit where the solvent vapor/air/moisture mixture is expanded, because the temperature here may go as low as 28 C., but the expansioncan take place into a space which can readily be arranged to avoid blockage by ice. In the heat exchanger the solvent vapor/air/moisture mixture is at a temperature above atmospheric so no ice formation can occur there.

Preferably air which has been separated from the liquid solvent is then heated and returned to the chamber. By this means, during. the stage of recovering solvent from the textiles, the air acts as a means of warming the textiles sufficiently, without any excessive local warming. In this way the solvent is recovered, while the moisture content of the textiles is scarcely altered. During the cleaning stage, while liquid solvent is present in the chamber, air and vapor may be withdrawn and subjected to compression, cooling. and expansion, and the chilled air then returned to the chamber without heating, to thereby prevent excessive pressure developing in the chamber. This means that the process may be operated in a wholly enclosed apparatus, without any need for a ventto relieve pressure. This assists in keeping consumption of solvent low.

Other features and many of the attendant advantages of this invention will readily be appreciated as the same becomes better understood by reference to the following detailed description of two preferred embodiments, when considered in connection with the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows the solvent circuit of a drycleaning plant of the invention in elevation, and partly in section; and

FIG. 2 shows the solvent circuit of a second plant, in diagrammatic form.

DESCRIPTIONOF THE PREFERRED EMBODIMENTS FIG. 1 shows a plant as described in my application Ser. No. 725,293, while FIG. 2 shows a plant which embodies the same invention, but also incorporates some improvements.

FIG. 1 shows as much of an otherwise conventional drycleaning plant as is necessary for an understanding of this invention. are to be A stationary. cylindrical cleaning tank having a horizontal axis is equipped with a nonillustrated door for introducing and withdrawing garments and the like which are to be drycleaned in a rotary, perforated drum, not itself relevant to this invention, which is represented by a circle 12 only. The tank 10 and the entire solvent circuit are normally sealed from the atmosphere.

Electric resistance heating elements 14 are arranged near the bottom of the tank 10, and a pipe 16a equipped with a centrifugal pump 18 draws liquid from the lowermost point of the tank 10 for delivery to a filter 20. A check valve 66 is arranged in the pipe 16a between the tank 10 and the pump 18, and a portion 68 of the line is transparent. A siphon 16b drains the liquid from the filter 20 to the top of a storage tank 22 whose bottom communicates through a shutoff valve 24 and connecting nipples 16c with the upper portion of the cavity 26 in the tank 10.

An approximately U-shaped duct 28 communicates with the cavity 26 through an intake orifice 30 and a discharge orifice 32 at a level higher than that of the orifice 30. Baffles 34 in the duct 28 create turbulence when vapor is drawn from the cavity 26 by a fan 36 in the duct 28, the fan being motor-driven in a conventional manner, not shown.

A mechanical refrigeration unit 38 draws vapor from the cavity 26 through the suction intake 40 of its compressor 42 which is driven by a nonillustrated electric motor. Cooling means 44 is connected to the compressor outlet, and condensed liquid and some noncondensed gas are discharged into the duct 28 near the baffles 34 through an expansion nozzle 46. The cooling means comprises a heat exchanger which is water cooled in a conventional manner. At least a major portion of the discharged liquid is caught in a trap 70 and is drained to the intake of the pump 18 through a return line 72 without entering the cleaning tank.

The storage tank 22 is equipped with a sight glass 48 and a valved overflow pipe 50 whose downwardly directed intake orifice is at approximately N5 of the total inner height of the upright cylindrical tank 22 above the tank bottom. Baffles 52 are arranged near the top of the tank 22 which is equipped with a mechanical refrigeration unit 54 closely similar to or identical with the aforedescribed unit 38. The suction intake I 56 ofa compressor 57 is at the very top of the cavity 58 in the tank 22, and a water cooled heat exchanger 60 connected to the high-pressure discharge conduit of the compressor 57 is equipped with an expansion nozzle 62 directed toward the baffles 52.

An auxiliary drain line 80 draws a portion of the filtered liquid from the bottom of the filter 20 into an evaporator 82 equipped with electric resistance heaters 84, and the vapors formed are drawn through a suction line 86 into a compressor 88 from which they are released at high pressure and temperature through a discharge line 90 into cooling means 92. An expansion nozzle 94 attached to the cooling means 92 is located in a condensate trap 96 connected to the cavity 58 in the tank 22 by a return line 98. A line 100 connects the trap 96 to the evaporator 82 to equalize the pressure in the respective vapor spaces.

The aforedescribed apparatus may be operated with a wide variety of solvents, preferably not miscible with water over its range of operating temperatures, but practical considerations normally limit its application to solvents having boiling points between approximately 9 C. (dichloro-fluoromethane) and 120 C. (perchloroethylene). lts advantages are greatest with solvents boiling between approximately 20 and 50" C., and monofluorotrichloromethane, which has a boiling point of 23.7 C., is typical both of the fluorocarbon solvents preferred for this invention, and of the solvents boiling in the preferred range. The operation of the apparatus will be described hereinafter with reference to CCl F.

Enough solvent is charged into the apparatus to maintain a liquid level 64 slightly below the orifice 30 of the duct 28 in the normal operating condition of the apparatus, that is, with a normal load of garments and the like (not shown) in the drum l2 and while the pump 18 is driven at its normal, constant speed. The valve 24 is adjusted during the cleaning operation to maintain the solvent level in the storage tank 22 just below the intake of the drain 50. The dwell time of the solvent in the tank 22 is long enough to cause dispersed water to collect above the solvent surface and to be drained off through the pipe 50.

The cleaning process is continued until the liquid passing the transparent section 68 of the line 16a is clear and all impurities insoluble in the solvent and released from the garments by mechanical action are transferred to the filter 20.

The ambient temperature is normally close to the boiling point of monofluorotrichloromethane, and the temperature of the solvent tends to rise because of mechanical energy being converted to thermal energy of the liquid by the pump 18 and the drum 12. The temperature of the circulating solvent and its vapor pressure are held within safe limits mainly by the refrigerating

units

38, 54.

A vapor mixture consisting primarily of solvent vapor, but also containing air, and water vapor extracted from the garments, is drawn into the duct 28 through the orifice 30 by the fan 36. More of the same vapor mixture is drawn into the refrigerating unit 38 through the intake 40, and is discharged from the expansion nozzle 46. Most of the solvent and the small amount of water present are released from the nozzle 46 toward the baffles 34 as liquids cooled well below the boiling point of the solvent so that additional solvent is condensed in the duct 28 from the mixture drawn through the orifice 30. A relatively small portion of the liquid solvent evaporates again so that the vapor discharged from the orifice 32 into the cavity 26 is significantly cooler than the vapor drawn into the orifice 30. More of the liquid solvent, still well below its boiling point, is caught in the trap 70 and holds the temperature of the pump 18 within adequate limits.

Similarly, solvent vapor is drawn from the vapor space in the cavity 58 of the storage tank 22, cooled in the refrigeration unit 54, and injected as liquid into the cavity 58 near the baffles 52, thereby controlling the temperature of the liquid entering the cleaning tank 10 from the bottom of the storage tank 22.

While a major portion of the solvent flows from the filter 20 to the storage tank 22 through the siphon 16b a smaller solvent portion is heated to its boiling point in the evaporator 82, and is cooled in the cooling means 92 and by the expansion nozzle 94, and is returned to the cleaning cycle in the storage tank 22. Soluble impurities extracted by the solvent from the gannents are retained in the evaporator 82 whose contents are drained to a nonillustrated waste receptacle from time to time.

When the cleaning operation is to be terminated, the valve 24 and the overflow pipe 50 are closed, and most of the solvent is removed from the tank 10 through the bottom opening and the pump 18. The heaters 14 are then energized, and the solvent evaporated from the heated garments is condensed by the refrigerating unit 38 and in the duct 28, collected in the trap 70, and ultimately transferred to the storage tank 22. The check valve 66 prevents liquid flowing in the return line 72 from entering the tank 10. The temperature and vapor pressure of the solvent in the storage tank 22 are controlled by the refrigeration unit 54 whose intake 56 is located high enough to prevent entry of liquid into the compressor 57 under all operating conditions.

Because the vapor pressure of the solvent in the tank 10 is ultimately determined by the temperature of the material leaving the expansion nozzle 46 which is in contact with the vapor in the tank 10, only traces of solvent remain in the tank 10 and in the garments when the tank is opened for removal of the clean garments. No solvent is lost during the cleaning operation because the refrigerating units permit operation in a tightly sealed system. A vent is not required.

The fluorinated hydrocarbons are therefore preferred as solvents but perchloroethylene and other chlorinated solvents having a fairly high vapor pressure at ambient temperature can be used. The advantages of the invention are greatest with solvents whose boiling points are only slightly above the prevailing ambient temperature, that is, approximately to 50 C. in moderate climates. The efficiency of .the refrigeration units increases with the partial pressure of the solvent vapor in the vapor mixture drawn into the units, and is highest with solvents whose boiling point is barely above ambient temperature under otherwise identical conditions. 7

The cooling means 44, 60, 92 transmit thermal energy from hot compressed vapors to water which need not be colder than the ambient air in order to be effective. Actually refrigerating units have been operated successfully in drycleaning plants of the invention with air-cooled cooling means. This is incontrast to heat-exchanging apparatus operating on solventat ambient pressure, whose efficiency approaches zeroas the boiling point of the solvent approaches the temperature of the coolant.

Solvents boiling below 50 C. have the added advantage that relatively little moisture is lost from textiles-during the 'last stage of the drycleaning cycle. The drycleaned garments therefore have a softer hand than those cleaned with relatively high-boiling liquids that mist ultimately be driven off at temperatures at which much water is lost from the garments. The cost of operating the refrigeration units is insignificant with fluorotrichloromethane even if the ambient temperature reaches C. and quitetolerable at an ambient temperature of C. is obviously higher with solvents whose boiling points are below 20 C. and such solvents are economical only where the ambient temperature is normally quite low or where electric power is cheap.

The refrigeration-units employed are compact and inexpensiven Their components are staple articles of commerce. Because the material to be cooled is used as the refrigerant, their operation is extremely simple and thermal losses are minimal.

in the second plant, plan, shown in FIG. 2, textiles are cleaned in a chamber 100, which contains a perforated rotary drum (not shown) as is usual in drycleaning machines. A supply of liquid solvent is held in a tank 102. For thecleaning of textiles which have been placed'in the chamber 100, valves V and V, are opened-to allow solvent to till the chamber up to a level indicated by a level-indicating device 104a or 104b, as may be required. Then the valve V, isclosed, and the drum is rotated (by means not shown) while liquid solvent is circulated by a pump 106 through a circuit, indicated by arrows A, including a valve V,, a button trap 108, a valve V,,, a filter 1-10 and valves V, and V A level switch 112 ensures that the pump must be flooded with solvent before it can be operated. This is a precaution against cavitation with a low boiling point solvent. In addition the valve V, isset to restrict the flow of liquid and so has a cooling effect. The same result may be produced by an orifice-at the pump outlet.

Before cleaning, the filter is coated with powder, .by circulating liquid througha valve V, bypassing the chamber 100. The powder is charged into the button trap. At the conclusion of cleaning, the valve V is closed and the valve V is opened so that liquid drains from the chamber 100 and is'returned to the tank 102. Further'liquid is extracted centrifugally by rotating the drum at high speed. Then the pump is stopped.

Residual solvent in the textiles is recovered by operating a compressor 114 in a circuit indicated by arrows B, C. A solvent vapor/air mixture is drawn from the chamber 100 through a connection 116 by the compressor, and'is delivered through a heat exchanger 118 and an expansion orifice 121 to the tank 102. Here condensed solvent collects while air returns to the chamber through a heater 122 and a connection 124.

The compressor raises the ressure of the solvent vapor/air mixture to about 7 to 8 atmospheres absolute. The temperature in the chamber 100 is about 0 to 20 C. and the pressure about 0 to 1 atmosphere above atmospheric, and the temperature at the outlet from the compressor, using monot'luorotrichloromethane as solvent, is about to l00 C. These figures relate to the start of recovery. The heat exchanger [.18 is a finned pipe coil'cooled-by a flow of atmospheric air drawn through it by a fan l26.-Between the heat exchanger and the expansion orifice there is a chamber 128 and a valve 120, which opens only when the upstream pressure exceeds a preset value. This ensures that the flow through the expansion orifice is always either nil orabove a minimum value, which ensures adequate temperature'fall. The temperature in the chamber 128 is about 25 to 40 C. It is undesirable for any condensation of vapor to commence in the chamber 128. Such condensation would mean thatfor the same work doneby the compressor 114 the pressure in-the chamber 128 would be less, and the cooling effect of. the expansion through the nonle 121 would be less. The pressure setting at which the valve 120 opens can be adjusted to suit the average atmospheric indoor temperature of the country in which the machine is being used, in therange l8 to 40 C. Thecompressor 114 may have an output greater than the 7 to 8 atmospheres absolute, mentioned above.

The expansion orifice 12] can consist of a length of narrow pipe, e:g., I00 mm. longand 4 mm. nominal diameter (about 2 mm. bore). The pressure in the tank 102 is about-0 to l atmosphere above atmospheric. The expanded solvent vapor/air mixture entering the tank 102 is wet" with solvent droplets due to thefall in-temperature caused by expansion. and these droplets join the main body of liquid solvent in the tank. The

.air attains a temperature of about 20to 30 C. Although the air issaturated with solvent vapor, the amount of vapor. at so low a temperature, is very small. There should be sufficient spaceabovethe liquid level in the tank 102 to enable the air to leave the tank without carrying droplets with it.

In the heater 122 the temperature of the air is raised from -20 to l20 C. By the end of the recovery. the temperature in the chamber 1001s about 23 to 25 C. and the pressure'about 0 to 0.02- atmosphere above atmospheric. The amount of solvent remaining inthe textiles after recovery carried'out in thiswayforaboutSto l0 minutes is insignificant.

The solventzvapor/air mixture drawn from the chamber I00 also contains-some moisture, originating from the textiles. On entering the tank 102 this becomes dissolved in the droplets of solvent. The quantity of moisture is too small to form any distinct body ofice. in the operation of recovering solvent from sludge by heating, described below, the temperatures used are so low that some moisture remains with the solids, and hence when the solids are discharged from the still. moisture also leaves the system. An equilibrium situation is thus reached, and there is no buildup of moisture within the system.

During the cleaning operation, the mechanical agitation produced by the rotation of the drum tends to raise the temperature of the solvent. To prevent too great a rise of vapor pressure, with possible danger of leakage, the circuit containing the compressor 114 may be operated as described above, but without use of the heater 122. In this way the chilled air returned from the tank serves to lower the temperature in the chamber There may be a control (not shown) arranged to cause the compressor tooperate in response to rise of pressure in the chamber above a predetermined value.

During the latter part of draining liquid solvent from the chamber, the drum may be rotated at high speed so as to extract liquid solvent centrifugally from the textiles. This highspeed rotation may be repeated at intervals during the subsequent recovery of solvent, alternating with low-speed rota tion, to assist the exposure of all parts of the textiles to the heated air.

From time to time sludge which accumulates in the filter is released through a valve V to a still 130. The sludge is then heated to enable solvent in the sludge to be recovered as vapor. This vapor, mixed with air present in the still. is then passed intoa circuit indicated by arrows D, E, containing a compressor 134, a heat exchanger 136, a chamber 138, a valve 140, an expansion orifice 141, a tank 142 and a heater 144, analogous to those in the circuit B, C. Liquid solvent collects in the tank 142 and is returned to the circuit A by opening a valve V from time to time. The conditions of temperature and pressure in the circuit D, E are generally similar to those in the circuit B, C.

In order to avoid any risk of local overheating, which can lead to cracking of the solvent, there may be electric or steam heater 132 spaced from the outside face of the lower wall of the still. An air gap of 5 to l mm. is satisfactory. Alternatively, use may be made ofa water jacket, itself heated by an electric immersion heater. Preferably the heater is controlled by a timer, with an overriding cutout sensitive to the temperature of the bottom ofthe still.

As an alternative, the compressor 134, between the still 130 and the heat exchanger 136, may be omitted. That is to say the pressure in the still, and the heat exchanger, as far as the expansion orifice 141, is established by application of heat to the still. This is a simplification which nevertheless is found to operate satisfactorily. [f the solvent is monofluorotrichloromethane, the heating of the still is preferably controlled by a thermostat in the still set at 30 C. lt is found that the working pressure is about 2 atmospheres absolute. A safety valve on the still is set at 3 atmospheres absolute.

Instead of the orifice 121 discharging into the tank 102, it may discharge into a distinct separation chamber, having a lower outlet to the tank 102, and an upper outlet connected to the air heater 122. For best efficiency, a distinct separation chamber is used in conjunction with intermittent flow, ensured by a valve such as the valve 120. Towards the end of each period of flow, pressure rises in the separation chamber and expels air quickly, with minimum pickup ofliquid.

Alternatively, the orifice 121 may deliver into the air space in the button trap 108. These alternatives also apply to the orifice 141.

lf desired, the chamber 100 may have a heater to supplement the efiect of the air heater 122.

The filter may drain not direct to the still, but to the button trap, from which liquid is pumped to the still. In a simplified apparatus there may be no filter, and no provision for circulating liquid during cleaning, Instead, there is provision for draining liquid from the chamber 100 into the still, as illustrated by the valve V Safety valves should be provided to protect the chamber and tanks against excessively high or low pressure. This is not the same as providing a vent which is continuously open.

Each liquid outlet from a tank is via a syphon, to ensure that vapor is not entrained into a vortex.

Monofluorotrichloromethane (CFCl is the solvent preferred in putting the present invention into practice. Other halogenated hydrocarbon solvents could be used, in particular monofluorodichloromethane (Cl'lFCl and trifluorotrichloroethane (CFCl,-CF,CI). The respective boiling points are 23 C., 8.9 C., 47.6 C. All are nontoxic and noninflammable. The first is preferred on grounds of cleaning effectiveness, and cost at the present time.

In smaller apparatus, e.g., with a capacity for 2.7 kg. of textiles at a time, the filter may have a throwaway cartridge element. Then no still is required. The amount of solvent lost when the cartridge is thrown away is small.

I claim:

1. In a drycleaning method in which textiles to be cleaned are agitated in a cleaning tank while immersed in a drycleaning solvent having a boiling point of 9 to l20 C., a major portion of the solvent thereafter is drained from the tank, the contents of the tank thereafter are heated until residual solvent is converted to vapor, and the vapor is removed from the tank, the improvement in removing the vapor which comprises:

a. compressing said vapor to an elevated pressure, thereby increasing the temperature thereof;

b. cooling the compressed vapor while maintaining the elevated pressure thereof; c. thereafter releasing said elevated pressure,

1. said elevated pressure, said increased temperature, and said cooling being sufficient to cause at least partial condensation ofsaid vapor to liquid; and

d, removing said liquid,

2. In a method as set forth in claim 1, said solvent having a boiling point between 20 and 50 C.

3. In a method as set forth in claim 1, said solvent being a halogenated hydrocarbon.

4. In a method as set forth in claim 1, said contents of the tank being heated to the boiling point of said solvent, and said cooling being sufficient to make the temperature of said liquid substantially lower than said boiling point, said liquid and said vapor being kept in contact with each other prior to said removing of the liquid.

5. A method according to claim 1, including removing air present in the cleaning tank with the solvent vapor separating the air from the resultant liquid solvent, and heating the separated air and returning it to the cleaning tank chamber,

6. A method according to claim 1 in which the solvent is monofluorotrichloromethane.

7. ln a drycleaning method in which textiles to be cleaned are agitated in a cleaning tank partly filled with a drycleaning solvent having a boiling point between 9 and l20 C., the remainder of said tank containing vapor of said solvent, the improvement which comprises:

a. withdrawing a portion of said vapor from said cleaning tank;

b. compressing the withdrawn portion ofsaid vapor until the temperature thereof increases;

c. cooling the compressed vapor while maintaining the pressure thereof;

d. reducing said pressure to a lower value,

1. said increased temperature, said pressure, said cooling, and the difference between said pressure and said lower value being sufficient to cause at least partial condensation ofsaid vapor to liquid; and

e. returning said liquid to said tank.

Claims

2. In a method as set forth in claim 1, said solvent having a boiling point between 20* and 50* C.
3. In a method as set forth in claim 1, said solvent being a halogenated hydrocarbon.
4. In a method as set forth in claim 1, said contents of the tank being heated to the boiling point of said solvent, and said cooling being sufficient to make the temperature of said liquid substantially lower than said boiling point, said liquid and said vapor being kept in contact with each other prior to said removing of the liquid.
5. A method according to claim 1, including removing air present in the cleaning tank with the solvent vapor separating the air from the resultant liquid solvent, and heating the separated air and returning it to the cleaning tank chamber.
6. A method according to claim 1 in which the solvent is monofluorotrichloromethane.
7. In a drycleaning method in which textiles to be cleaned are agitated in a cleaning tank partly filled with a drycleaning solvent having a boiling pOint between 9* and 120* C., the remainder of said tank containing vapor of said solvent, the improvement which comprises: a. withdrawing a portion of said vapor from said cleaning tank; b. compressing the withdrawn portion of said vapor until the temperature thereof increases; c. cooling the compressed vapor while maintaining the pressure thereof; d. reducing said pressure to a lower value,