US 3728074 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
Apnl 17, 1973 VICTOR 3,728,074
PROCESS FOR THE CLEANSING OF GARMENTS AND TEXTILES 2 Sheets-Sheet 1 Filed June 13, 1961 uvwgNroR. Ir v/ng V/cf0r BY W M M A TTORNEYS I. VICTOR A ril 17, 1973 PROCESS FOR THE CLEANSING OF GARMENTS AND TEXTILES 2 Sheets-Sheet 2 Filed June 13, 1961 3 wkm kwmmbmdi ENDS x92 MSQQS mmksx K01 83 Sam $553 Q Q R w .wwkbate 1 w bxb Aw m m E NC N W R m m r g A U l N 1 United States Patent Oflice 3,728,074 Patented Apr. 17, 1973 US. Cl. 8-142 8 Claims ABSTRACT OF THE DISCLOSURE A process of dry cleaning textiles and garment materials with compositions including 1,l,2-trichloro-1,2,2- trifiuoroethane, trichloromonofluoromethane, and methyl chloroform, wherein the materials are washed and dried at low temperature, together with steps or procedures for the economical handling and recovery of solvent.
This invention relates to improvements in the cleansing or cleaning of materials with organic solvents. In general, the invention is concerned with the cleansing or cleaning of garments and textiles of all kinds with organic agents including synthetic solvent, and the economical handling and recovery of the solvent. More particularly, the invention is concerned with providing process by which those serving the public, or the general public itself in self-service establishments may satisfactorily cleanse garments and textiles, and in which proper safe guards are provided for the protection of personnel, and the materials being cleansed, and in which the solvent can be economically recovered for reuse.
The earliest method of dry cleaning garments and the like, consisted of applying a liquid organic solvent to a cloth and brushing or sweeping the garment to loosen the soil and transfer it to the solvent ladened cloth. The garments were then hung in contact with air for the evaporation of the residual solvent vapors. This type of cleaning did not remove embedded soil and consequently a dry cleaning trade came into existence that performed the cleansing operation with the use of commercial apparatus, which embodied immersing the textiles in the liquid solvent and suitably agitating the mixture to remove the soil, whereafter the textiles were placed in a closed chamber and the residual solvent removed by means of a column of air with much of the vapors being discharged to the atmosphere. The solvents used in the earlier operations were the natural hydrocarbons derived from petroleum or coal, or mixtures thereof. While some of these solvents have good cleansing properties, they are all highly flammable and have a low flash point, and are, therefore, dangerous to use, and have frequently been the cause of accidents in the home or in dry cleaning plants.
To surmount the fire hazard associated with the natural hydrocarbons, the chlorinated hydrocarbons came into use for dry cleaning purposes. The earliest solvent of this class was carbon tetrachloride. Although the cleansing power of carbon tetrachloride is passable, and the solvent is completely nonflammable, it was not satisfactory for dry cleaning purposes because its vapors are highly toxic, and when the solvent is used in the presence of moisture, even in relatively small amounts, it decomposes liberating free chlorine, which in addition to being toxic is also corrosive to surrounding metal surfaces.
Other forms of non-stable chlorinated hydrocarbons received passing attention, but when the chemical industry succeeded in synthesizing perchlorethylene, this solvent received wide acceptance, and it is in general use at this time by the dry cleaning trade. Perchlorethylene is stable and less toxic than carbon tetrachloride and it has good cleaning properties, as indicated by its high Kauri butanol number; in fact, its solubility powers are so great that the solvent causes injury to some forms of buttons and ornaments used in conjunction with garments, and it may cause bleeding of certain types of dyes, particularly when those dyes are applied to fabrics by printing, such as in the case of draperies. Also, its high solvency power tends to impart a harsh texture in some types of textiles, making it necessary to use an additive having lubricating qualities to give a softening effect to the textiles. The chief objection to perchlorethylene is in the difi'iculty of removing the solvent and its vapors from textiles after cleaning. The solvent has a high boiling point and a relatively low vapor pressure, so that the vapors are not readily evaporated at a low temperature, and consequently, in order to speed up the drying operation, it is necessary to force heated air through the textiles. In the conventional practice of cleansing textiles with perchlorethylene, after the free solvent has been removed by rotary extraction, the drying is performed by blowing air heated to a temperature of l50190 F. through the materials. Blowing heated air through the textiles is objectionable because it creates a static charge in the textiles, and this in turn causes linting. Also if garments contain stains of a non-soluble nature, heating may cause many such stains to be set in the material. The presence of staining substances in garments is a cause of considerable concern to the dry cleaning trade, for if the stains become permanent, the customer may make a claim for damage. The removal of stains is a specialized practice, and experience has taught that except for stains which have become permanent before cleaning, they can best be removed if the fabric has not been heated, so that it is preferred that the cleaning process not embody the use of heat or of heated air for solvent vapor removal, and this is particularly true in the absence of expert service.
In recent years, and subsequent to the development of automatically operated home laundry equipment, such as washers and dryers, there has been a phenomenal growth of self-service establishments where by the use of coin operated equipment, the general public may launder textiles and garments without having to make the capital investment necessary to purchase such equipment. -I have recognized that there is an existing need for dry cleaning apparatus to be made available to the general public in self-service establishments, similar to coin operated laundries, for the reason that the cost of dry cleaning of garments of the class that normally cannot be laundered has been such that much of the public do not ordinarily clean such garments as frequently as might be desirable for their proper care. Provision of a self-service dry cleaning system does, however, present many problems, since dry cleaning operations normally require the services of skilled operators, and to be successful, self-service establishments for this general purpose must require only a minimum of maintenance by a skilled person.
In the present invention, I have provided an improved concept of dry cleaning garments and textiles, that involves a substantial departure from recognized procedures and apparatus, and which is of such a nature that it might be safely utilized by the general public in selfservice cleaning establishments, as well as by the trade that serves the general public.
One feature of the present invention, which embodies a major departure from the prior practices, is in the selection of the cleansing solvent. I have found that 1,1,2-trichloro-1,2,2-trifiuoroethane is a highly desirable solvent for dry cleaning purposes. This solvent is quite remarkable, forwhile it is comparable to perchlorethylene in cleansing power, it is compatible with garments and textiles, and it s q 's uameuro pua suonnq oustqd o1 snormgur-uou st solvent is extremely safe for use in dry cleaning, because of its low toxicity and the fact that it is non-flammable. Theselection of a solvent of this class for dry cleaning of garments and textiles represents a radical departure from the;prior practice because this solvent has a low boiling point and a relatively high vapor presure, and it has a relatively high rate of evaporation. These seemingly undesirable characteristics may however be advantageously used under proper conditions. Garments and textiles cleansed with thissolvent can be readily dried with air at ambient temperature, which greatly shortens drying time and also makes it unnecessary to heat the fabrics for vapor removal. Also, because of its low boiling point, when 1,1,2-trichloro-1,2,2-trifiuoroethane isburdened with soil which it has removed from the textiles, the solvent can be easily purified by distillation at a relatively low temperature, thus avoiding the expensive purifying systems used in the past that required filtration and involved several procedural steps which required special apparatus. However, because of its high volatility and the fact that it is much more costly than the non-flammable solvents used in the past, special precautions must be followed in handling this solvent, and in the recovery of the vapors thereof. Consequently, the apparatus in which the textiles are cleansed must be substantially airtight and must embody provisions for purifying the solvent by distillation, together with appropriate means and procedures for conserving and recovering the highly volatile vapors formed during the several procedural steps. i I have also found that another highly volatile solvent, trichloromonofluoromethane, can be used as a cleansing solvent. This solvent is less expensive than 1,1,2-trichlorb- 1,2,2-trifluoroethane, and has a lower boiling point, but under proper conditions could be substituted for use in dry cleaning textiles. I
Because the present system in all of its various phases deals with costly evanescent solvents, particular care must a be exercised inthe handling and transfer of the liquid and its vapors during the various steps of the procedure, with care being exercised to recover the vapors' during each stage of the process, and particularly during the drying'jof the textiles. While it is possible to condense a high percentage of the vapors by bringing them into contact with a cold surface, such as a refrigerant evaporator and/ or to combine refrigeration with an adsorption medium, a generally preferred process is to gather or catch the vapors with an adsorbent, and then recover the liquid solvent by steam distilling the adsorbent. It is recognized that the recovery of the vapors of a dry cleaning solvent .by an adsorbent is not basically new, for I have disclosed one method of performing this operation in my prior Pat. 2,910,137. However, the procedure and apparatus 'dis closed in my prior patent is not well adapted 'foruse'in the'system forming the present invention. It is presently contemplated that the system disclosed herein wouldbe used by the general public in a self-service establishment. These conditions require that the unit be operable by 'a person having no technical skill and that the unit be capable of v repeated independent operation in' rapid sequence; Moreover, the entire unit must occupy a minimum of space. To meet these requirements, each cleaning unit is preferably provided with a pair of adsorbers, each of which'is capable of receiving all of the vapors formed 4 during the cleansing and drying of one or two batches of garments or textiles. Thus, the unit is adaptable to batch operation, and while one of the adsorbers is receiving vapors, another will normally be undergoing desorption and cooling.
I have found that a highly eflicient adsorption system may be composed by utilizing a pair of cylindrical adsorbers of limited size, each of which contains a bed of activated carbon or equivalent adsorbent sufficient to safely receive all of the vapors formed during the cleansing of one batch of fabrics. I have also found that by following certain procedures, the adsorption efiiciency of each of the adsorbers may be substantially increased. Under the ordinary circumstances of combining a large volume of air with solvent vapors, after at least one initial use, the activated carbon will only retain about 8% of its weight of adsorbed solvent before breakthrough of unadsorbed vapors. However, I have found that the adsorbing capacity of activated carbon can be increased to the range of 30%40% of its weight of solvent before breakthrough by a number of combined steps. I have also found that the capacity of the carbon can still be maintained substantially above 8% by the elimination of some of the steps. The several improvement steps embody: passing a vapor rich mixture to the adsorbent at a relatively low velocity; shutting down the flow of air to the adsorption bed immediately after the drying of the clothes; and/or obtaining a substantially dry carbon bed after desorption. This latter step can be accomplished by the use of superheated steam, heated air, or prolonged use of air at a high velocity, or a combination of these factors.
During the various steps of the procedure, other than the direct drying of the fabrics by the passage of air in contact therewith, a certain amount of voltile vapors are formed during the transfer of liquid solvent, and a venting system is provided for collecting these vapors, as well as vapors that might be formed as a result of spillage or leakage of the solvent. These lesser amounts of vapors are normally combined with a column of ambient air passing to one of the adsorbers following a desorption operation.
In a typical operation of the entire system, a complete washing and drying cycle can be performed in a minimum period of about 15 minutes or less, using dual adsorption apparatus, and an adequate distillation apparatus for purifying the solvent. The operations may continue indefinitely on such cycles, requiring only periodic removal of still residue, and occasional replenishment of the solvent supply. If the apparatus is in proper working condition, total solvent losses are minimized to about 20 grams of solvent per pound of textiles cleansed.
To aid in soil removal from the textiles and to prevent redeposition thereof it is desirable to incorporate with the solvent during the cleansing stage a surface active agent which is compatible with the solvent and preferably forms a colloidal suspension in the solvent, and which will form an emulsion with water. It is recognized that the textile fibers will normally absorb and retain moisture from the air and such natural moisture will ordinarily be sufficient cleansing operation.
In the preferred embodiment of the present process, the textiles are first subjected to a washing action with a mixture of solvent and additive, whence the soil ladened liquid is extracted and removed. This is followed by a rinsing action with an equal volume of clean solvent, which after agitation is also extracted and removed from the textiles before drying. I
To accommodate the apparatus in which the various steps of the process are conducted for use on a selfservice basis by the general public, the apparatus is pro vided with motorized controls which are placed under the automatic control or semiautomatic control of a'programming device, such as to preclude error in operation.
An object of the invention is to provide improvements in the dry cleaning of garments and textiles of all kinds by a system composed of process and apparatus which is safe for the personnel conducting the operation, and the materials undergoing treatment.
Another object is to provide a process and apparatus for the economical use and recovery of relatively costly evanescent solvents for purposes of dry cleaning garments and textiles.
A further object is to provide a system for the cleansing of textiles with low boiling solvents, wherein such solvents can be substantially fully recovered, so that the cleaning process can be economically conducted.
Other and further objects may become apparent from the following specification and claims, and in the appended drawing in which:
FIG. 1 is a partially schematic elevational view, with some parts broken away, of apparatus for dry cleaning of textiles and the like, together with means for recovering solvent vapors; and
FIG. 2 is a timing diagram illustrating the sequence of operation of parts of the system shown in FIG. 1.
Having reference to the accompanying drawings, the invention will now be explained in detail.
Referring to FIG. 1, reference character designates the casing of a combined washer-dryer utilized for the dry cleaning of garments and the like and is provided on its front surface with an access door 12. Casing 10 is also provided with an air inlet 14 sealed by a movable damper 16 that is controlled by an actuator 18 connected thereto. Although not specifically shown the door 12 and damper 16 carry suitable resilient gaskets or other sealing means so that when closed, they substantially seal their respective openings in casing 10. Within the interior of the casing and illustrated with dotted lines is a formainous cage 20 which is adapted to hold the garments or textiles to be cleaned, and is rotatably driven by a motor 22 controlled by a 2-speed actuator 24. A belt or similar transmission 26 extends from motor 22 to a suitable connection with the cage 20.
A substantially airtight container 28 constitutes a solvent reservoir from which liquid solvent is supplied to the interior of casing 10 by a pump 30 which may be immersed in the liquid in container 28. The pump delivers the liquid through a conduit 32 containing a suitable valve 34 controlled by an actuator 36. Since the casing 10 and its associated parts are substantially airtight as liquid is admitted to casing 10, gases or air within the interior of said casing will be displaced, and these gases are permitted to pass through a conduit 38 which returns to reservoir 28 and contains a valve 40 controlled by an actuator 42. The reservoir 28 has disposed therein a cooling coil 44 which is normally connected to a source of coolant.
A smaller container 46 constitutes a reservoir for the additive which is combined with the cleansing solvent. A pump 48 which may conveniently be disposed Within container 46 has its low pressure side communicating with the reservoir 46 and discharges into a conduit 50 to a receiver 52 which has a return conduit 54 connected thereto and returns to the reservoir 46. A conduit 56 extends from the receiver 52 to container 10 and is provided with a valve 58 which is controlled by an actuator 60.
After the washing action is completed, the used solvent within container 10 is passed through a conduit 62 that contains a valve 64 controlled by an actuator 66. Conduit 62 extends to a still 68. The still 68 is connected to the reservoir 28 by a pressure balancing conduit 70 that contains a check valve 72. The still 68 is also provided with a heat exchanger disclosed as a coil 74 that is connected to a source of heat, such as a hot water system, and as disclosed, a 2-Way valve 76 controls the fiow of the hot Water either to the coil 74 or to a conduit 78. The valve 76 is controlled by an actuator 80. Still 68 is provided with a drain line 82 that contains a manual valve 84. Extending from the still 68 is a distillate conduit 86 that extends to a condenser 88. A conduit 90 extends from the bottom of condenser 88 to a cross 92 situated above a liquid separator 94. A conduit 96 extends from separator 94 to the reservoir 28 and constitutes a solvent return to the reservoir.
To collect solvent vapors formed during various stages of the process, a trunk duct 98 extends to a casing portion 100 that contains an appropriate filter bag, not shown, that may be periodically exchanged through a door 102 leading into the interior of casing 100. A fan casing 104 contains a fan rotor 106 driven by a suitable motor 108. The low pressure side of the fan rotor 106 communicates with casing 100 for drawing vapors into the trunk duct 98. At the outer end of duct 98 is a container 110 that forms a collector and mixing chamber for vapors. A vent conduit 112 extends between the reservoir 28 and container 110 and a second duct 114 extends between cross 92 and container 110 and is joined by a branch conduit 116 extending from conduit 96 and serves to prevent conduit 96 from syphoning all of the liquid from the separator 94. An open ended conduit 118 extends into the upper part of container 110, and contains a damper 120 that is controlled by an actuator 122. A conduit 124 whose lower portion is shown by dotted lines extends from a lower portion of container 10 to the trunk duct 98. Duct 124 contains a damper 126 controlled by an actuator 128. It will be noted that the inlet end of duct 124 is generally diametrically opposed to the inlet opening 14 of container 10.
The discharge portion of fan casing 104 extends to a conduit 130 which is joined to a T from which extend branches 134, 136. Each of the branches 134, 136 communicate with the upper extremity of a pair of adsorbers designated by reference characters 138, 138a. These adsorbers are similar in construction and therefore only one will be described. The adsorber consists of a casing 140 having an inlet connection 142 with branch 134 which is controlled by a damper 144, which in turn is controlled by an actuator 146. Within its interior, the casing carries a foraminous plate 148 that supports a mass of adsorbent here disclosed as pellets of activated carbon designated by reference character 150. Beneath the formaninous plate 148 the container 140 is provided with an exit opening 152 that is controlled by a damper 154 which in turn is connected to an actuator 156. The discharge openings of each of the adsorbers extends to a duct 158 having an outlet connection 160 that may extend to a point exterior to the enclosure in which the equipment is situated.
To desorb the carbon pellets 150, a conduit 162 extends from a source of steam to a valve 164 controlled by an actuator 166. Extending from the upper extremity of the container 140 is a conduit 168 containing a valve 170 controlled by an actuator 172. The conduit 168 extends to a T 174 from whence a vapor line 176 extends to a condenser 178. A condensate conduit 180 extends to cross 92 above the liquid separator 94. The condenser 178 is shown with a cold water connection 182, and a hot water discharge pipe 184 that extends to valve 176 and forms a source of heating liquid for coil 74.
The several elements associated with the adsorber 138 have their counterparts in the adsorber 138a and the several parts bear the same reference character as for adsorber 138 with the letter a appended thereto.
To control the various actuators and motors associated with the apparatus, there is provided a program timer 185, that contains a number of electrical relays and switches which are in turn joined to the various electrical devices described heretofore by electric conductors, not shown. The program timer 185 and its associated conductor s is conventional, and is not described in detail.
Considering next the solvents, which have been described heretofore, the following table derived principally from information published by E. I. du Pont de Nemours Company, Inc., sets forth the pertinent characteristics of these solvents:
CHA RACTE RISTICS OF SOLVENTS where it intermingles with the damp fabrics being tumbled in the cage 20. The admission of air into container Kauri Toxicity Flashbutanol (MAC) able value p.p.m.
N orrz. -With respect to the evaporation rate, the rate listed is not an absolute value, butis based on the evaporation of carbon tetrachloride under a particular set of conditions. The relative rate will probably be similar under other conditions. However, the values listed in the table should be considered only as a guide and not as a precise value.
An additive is combined with the solvent to increase the cleansing power thereof and to hold soil in suspension in the solvent to prevent redeposition on the textiles. The additive must be compatible with the solvent and preferably should form a colloidal suspension in the solvent. The additive must be capable of forming an emulsion with water and since these characteristics are found among most detergents and surfactants, a wide range of materials can be used for this purpose including alkyl sulfates and alkyl amides, and several varieties of soaps. Normally the additive is combined with solvent and supplied to the container 46. Generally a small amount of the additive is combined with the solvent in proportions to give not more than about 0.l%0.5% by weight of the additive in the batch of solvent used for washing in container 10.
A typical operation of the process and the apparatus during a cleansing operation will now be described. As shown, the system operates in a timed sequence under the direction of the control 185, and with reference to FIG. 2, the periods of operation of the various parts of the apparatus are indicated in black, and periods when those various devices are inoperative are shown as blank space. Normally, the control 185 is energized when the proper number of coins have been deposited in a conventional coin operated control, but it should be understood that it is within the scope of the invention that various parts of the apparatus may be manually energized and the periods allowed for the various operations are subject to change.
A weighed load of textiles or garments are placed in the cage 20 and door 12 is closed. The system is then placed in automatic operation by control 185. Pump 30, valves 34, 40 and 58 are simultaneously energized so that a charge of solvent from the reservoir, and a small charge of solvent and surfactant are simultaneously admitted to container 10, and concomitantly air and vapors present in the container are forced through conduit 38 to the reservoir 28. Then motor 22 is energized to rotate the cage 20 at slow speed to perform the Washing action. When the washing time limit has been reached, valve 64 is opened and the cage 20 is rotated at a higher speed to centrifuge the soiled solvent from the fabrics, and transfer the same to the still 68, whereafter valve 64 is closed and the cage is again rotated at a slow speed. Then pump 30 is again energized to deliver a second charge of clean solvent to provide a rinsing operation, and after a short period valve 64 is again opened and the cage is again rotated at a high speed to dispose of the free liquid solvent to the still 6 8. Then, valves 64 and 40 are closed and the system operates to perform the drying operation.
The fan rotor 106 has been in operation during the washing and rinsing action, and during this same period damper 120 has been opened to permit air to flow through duct 98 to the active adsorber 138, or 138a, and such air as is passing through the duct will carry with it any vapors that have been forced into container 110 from the conduits 112 and 114 in a volume sufiicient to admix with the air entering opening 118 in container 110. When the drying operation commences, damper 120 is at least partially closed to materially reduce air flow from the inlet 118, and dampers 16 and 126 are opened thereby permitting air ambient to container to enter opening 14 10 sweeps the vapors downwardly into the open end of duct 124 whence such vapors are drawn by the fan into trunk duct 98 and forced into one of the adsorbers 138, 138a. It may be assumed that the normal capacity of the fan 106 is such that it would draw substantially cu. ft. of air per minute into container 110 where such air would flow at a rate of about 75 linear feet per minute to the adsorbent. But when the main source of air is cut oli and damper 16 is opened the flow of air through the small opening 14 in container 10 is diminished to about 20 cu. ft. per minute or less. This phase of the operation is relatively important, because the apparatus is now functioning to remove the residual solvent from the textiles, transferring the same to the adsorbent 150, and it is desirable that the highest possible concentration of vapors be maintained in the gases passing to the adsorbent.
Initially the vapors passing to the adsorbent 150' will be in a relatively pure condition since they are merely being swept to the adsorbent by the limited amount of air entering container 10. As the rich vapors contact the adsorbent, a substantial rise in temperature of the adsorbent occurs. It has been observed that the temperature of the adsorbent will rise to a degree substantially above the boiling point of the solvent, if the adsorbent is relatively dry. Since the rate of flow of the vapors to the adsorbent has been reduced from the original air speed, the adsorbent becomes progressively saturated from its upper extremity and any air contained in the gases is stripped of vapors before it is discharged into the duct 158. Each of the adsorbers is, of course, provided with suficient adsorbent to fully adsorb all vapors formed in one batch operation plus a safety factor of about 20% to avoid any possible loss of solvent. Because of the high volatility of the solvent, the vapors are readily liberated from the textiles so that at the end of approximately 4 minutes from the opening of damper 16 the textiles are substantially dry and at most will retain only a minimal unmeasurable amount of solvent. If the adsorbent was relativel free of moisture at the time the heavy concentration of vapors commenced to flow therethrough, I have found that commencing from the top of the adsorbent mass the pellets of activated carbon will retain a relatively large amount of solvent being in the range of substantially 25% or more of the weight of the adsorbent.
Distillation of the used solvent occurs during all phases of operation, except during the transfer of the rinsing charge from container 10. As disclosed in the drawing, heat for distillation is provided by the energization of the actuator 80 to rotate the two-way valve 76 so as to divert the how of hot water from the discharge line 78 to the coil 7-4. As disclosed, the source of hot water is from the discharge 184 of condenser 178, but it should be understood that any other source of heat can be utilized for this purpose. When 1,1,2-trichloro-1,2,2-trifluoroethane is utilized as the cleansing solvent, water having a temperature of F. is an adequate source of heat, and under normal conditions, the two charges of solvent in the still 68 can be distilled during the cycle time for processing one batch of textiles. The distilled solvent is cooled in condenser 88 and passes to the liquid separator $4 and is returned to the reservoir 28 through the conduit 96. The cooling coil 44 in the reservoir 28 is provided to maintain the temperature of the solvent therein sufficiently low to avoid the formation of any substantial amount of vapors.
During the several stages of the process, including the charging of container 10, the distillation of solvent from still 68, and the recovery of solvent from the adsorbent,
a certain amount of vapors of the highly volatile solvent are formed, and these vapors are transferred through the conduits 112 and 114 to the container 110, where they enter the lower portion of said container. Such vapors as build up within the container 110 are admixed in the upper portion thereof with air entering the conduit 118, and are passed through the trunk duct 98 to one of the adsorbers, so that substantially all such vapors formed anywhere in the system are conserved.
With the commencement of one washing cycle in the container 10, the last adsorber used for adsorption of vapors undergoes a desorption operation which is accomplished by the closing of the upper and lower dampers 144, 154, the opening of valve 170, and the admission of steam through valve 164 into the lower portion of the adsorber. That action permits steam to pass upwardly through the adsorbent passing outwardly through the conduit 168, and the vapor tube 176 to the condenser 178, whence the condensate passes through the conduit 180 to cross 92 and the liquid separator 94. Following the application of steam, air in a large volume is passed through the adsorbent to cool it, and more importantly, to evaporate moisture deposited on the particles of the adsorbent. Adsorption is a selective process, and as the organic vapors contact the particles moisture is displaced, which causes a desired cooling of the adsorbent; however, the displacement action tends to retard the rate of adsorption, and it also limits the extent to which the adsorbent can be loaded with the organic vapors.
Desorption and drying of the particles can be accomplished in different ways. One method is to use superheated steam, preferably of a temperature above 300 F., for at that temperature any condensate will be eventually removed. This treatment is then followed by passing ambient air through the adsorbent, principally to cool it. Another method is to utilize an aqueous fluid of lower temperature and follow it with air which has been substantially heated, as by a heater 186 disposed in duct 98, 5 and controlled by an actuator 188-. In either instance, the result sought is to reduce the moisture content of the adsorbent. As a measure of the desired degree of dryness of the adsorbent the air leaving the adsorbent should have a relative humidity of substantially 25%-30%. Under these conditions the adsorbing capacity of the activated carbon can be increased to 25% or more of the weight of the carbon before breakthrough of the vapors occurs.
In the manner described, a batch of garments or textiles may be cleaned and dried, on a dry-to-dry basis within substantially 15 minutes, although any of the steps of the process may be extended to a longer period if desired.
The maintenance of the unit requires a periodic removal of soil and residue from the still 68. For this purpose a temporary steam connection, not shown, is coupled to the still 68 to sweep solvent vapors therefrom, and thereafter the valve 84 is opened to remove the residual muck. It is also necessary to periodically add new solvent to the container 28, and to add a mixture of solvent and the emulsifying additive to container 46.
The selection of the solvent to be used as the cleansing agent is largely a matter of individual choice. At the time of submitting this application, 1,1,2-trichloro-1,2,2-trifluoroethane is the most expensive solvent, but based on its overall characteristics, it is the preferred solvent. Trichlo- 70 ro monofluoromethane is an efficient cleanser and is considerably cheaper, but because of its low boiling point this solvent is more difiicult to handle, particularly in areas where the ambient temperature is above the boiling point of the solvent. Under those circumstances, a sub- 10 stantial cooling system must be used in conjunction with reservoir 28 to maintain the solvent at a temperature not in excess of substantially 72 F., or the system must be modified to operate under pressure.
Emphasis has been placed upon the procedural steps of washing the textiles with a combination of solvent and an emulsifying additive and extracting this soil ladened liquid from the textiles followed by a rinsing action with clean distilled solvent. Repeated tests have established that superior soil removal may be accomplished by this procedure as compared to a continuous circulation and filtration of an additive bearing solvent, as practiced in the prior art. This new procedure enables the system to operate on a much smaller amount of liquid solvent than has heretofore been possible. By utilizing a low boiling point solvent, together with a distillation system, relatively pure solvent can be quickly recovered, so that it is unnecessary to maintain a large supply of solvent for the system.
The principal advantage of the present invention is in the greatly reduced amount of time necessary to properly clean and dry fabrics. With the process and apparatus disclosed herein, a complete cleaning cycle can be obtained in approximately /3 to A of the time presently required in processes and apparatus currently available. This shortening of time not only adds to the public convenience, but greatly reduces the capital investment in equipment required to process a given quantity of textiles.
Another important advantage of the present invention is in the provision of the safe and economical method of dry cleaning garments and textiles of all kinds. The use of a solvent having a relatively low Kauri butanol number leaves the textiles in a better condition and prevents damage to materials having fugitive dyes, and to garments having plastic buttons or ornaments. By utilizing a solvent having high maximum allowable toxicity level, the process can be made safe for use by the general public, and even in the event of spillage, the ventilating system provided by container with its air inlet opening 118 near the fioor level can conserve the lost vapors.
By utilizing a solvent of high volatility, and particularly in a moving column of air, the textiles can be quickly dried without heating, so that if the garments contain stains, these stains will not be set in the fabric.
By providing the apparatus and process described heretofore to be utilized in self-service establishments a new industry is created which will be of great benefit to the public, for this invention makes it possible to properly cleanse garments and other textiles at a very low cost, and in a remarkably short period of time.
The invention is not limited to the disclosure of the drawings, which are merely illustrative, but it is defined in the terms of the appended claims.
1. A process of dry cleaning textiles with a nonflashing chloro-fluorohydrocarbon solvent having a vapor pressure in excess of 300 at 25 C., said solvent having a Kauri butanol value not substantially in excess of 70, an evaporation rate substantially greater than that of carbon tetrachloride and a toxicity level of at least 500 p.p.m. in air, which comprises:
(a) placing textiles in a closable container and closing said container;
(b) charging the closed container with solvent from a reservoir of solvent while concomitantly collecting air and vapors displaced from said container by in coming solvent by allowing said air and vapors to pass through a channel combined with said container and containing a vapor recovery system to effect disposition of solvent in said reservoir;
(c) subjecting the textiles in the container to mechanical action while washing said textiles and allowing solvent vapors generated by said action to pass through a channel combined with said container to said solvent vapor recovery system to recover the solvent;
(d) removing the solvent after the washing operation to a reservoir other than the aforesaid reservoir and purifying the solvent for reuse; Y
(e) drying the textiles in said container and allowing vapors formed to pass through a channel combined with, said container to said solvent vapor recovery system;
(f) said process being such that the total solvent vapor loss is no more than about 20 grams of solvent per pound of textiles cleaned.
2. The process as claimed in claim 1, wherein the solvent vapors are directed to a body of solid adsorbent to collect the solvent vapor which is recovered from the adsorbent by steam distillation.
3. The process as claimed in claim 1, in which the chloro-flurohydrocarbon solvent is 1,1,2-trichloro-l,2,2- trifluoroethane.
4. The process as claimed in claim 1, in whichthe chloro-fiuorohydrocarbon solvent is trichloromonofluoromethane.
5. The process as claimed in claim 1, in which the flow of gases to the solvent vapor recovery system is controlled to reduce the rate of flow of said gases when the proportion of solvent vapors therein is relatively high.
6. The process as claimed in claim 5, wherein the solvent vapors are directed to a body of solid adsorbent to 12' collect the solvent vapor which is recovered from the adsorbent by steam distillation. 1 7. The process as claimed in claim 5,'in which the chloro-fluorohydrocarbon solvent is 1,1,2-trichloro-1,2,2'- trifluoroethane.
8. The process as claimed in claim 5, in which the chloro-fluorohydrocarbon solvent is trichloromonofluoro methane. a
References Cited UNITED STATES PATENTS I 1 I 2/1932 Welles et al. s '142 GEORGE LESMES, Primary Examiner I CANNON, Assistant Examiner US. Cl. X.R.
68-18 C, 18 R; 3475, 252l62, 171