US 3801274 A
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United States Patent 1191 Gleason METHOD FOR CLEANING FABRICS AND CLOTHES  Inventor: John OFarrell Gleason, 1907 Third Ave., Milwaukie, Oreg. 97222 22 Filed: Dec. 13, 1971 211 Appl. No.: 207,181
 US. Cl....: 8/l42, 8/l37, 68/18  Int. Cl D061 1/00  Field of Search 8/142, 137; 68/18  References Cited UNITED STATES PATENTS 3,134,990 6/1964 I Bodine, Jr 8/137X I [111 3,801,274 [4 1. Apr. 2, 1974 Primary Examiner-Mayer Weinblatt Attorney, Agent, or Firm-Oliver D. Olson  ABSTRACT A mixture of water and a cleaning. solvent having a boiling point lower than water is used to clean fabrics, clothes and like materials, and there'after'the solvent is recovered by subjecting the mixture to microwave energy at a frequency which causes heating only of the water molecules which, in turn, effect heating and selective vaporization of the solvent.
5 Claims, 2 Drawing Figures METHOD FOR CLEANING FABRICS AND CLOTHES BACKGROUND OF THE INVENTION This invention relates to the cleaning of fabrics,' clothes and the like, and more particularly to novel method and apparatus by which to achieve substantially complete refining and recovery of cleaning solvent after each cleaning cycle.
Conventional dry cleaning processes utilize a solvent, for example per'chloroethylene, having a boiling point greater than water, which is continuously filtered to remove solids. Periodically, for example once a day, the solvent is distilled to refine it. A significant amount of the solvent is lost by evaporation and by retention in the clothes and in the distillation residue, and therefore must be replaced at significant cost.
Attempts have been made heretofore to utilize a cleaning solvent, for example trichlorotrifluoroethane, commonly known as R-ll3, having a boiling point lower than water, by operating the apparatus under high vacuum and redistilling the solvent after each tion and condensing system. Accordingly, such apparatus is very costly, bulky and heavy. Moreover, the distillation residue constitutes an ecolologically deleterious waste product which presents a problem of disposal.
Conventional laundering involves the use of large volumes of hot water together with significant amounts of soaps, detergents, water softeners and like additives, all of which are discarded after use. It has been estimated that the amount of water utilized for laundering in the United States represents an average of at least about 25 gallons per person per week. The initial costs involved in providing and heating such quantities of water and additives are significant. Most important, however, is the deleterious ecological effects resulting from the disposalof such magnitudes of waste.
SUMMARY OF THE INVENTION In its basic concept, this invention utilizes microwave energy of a frequency predetermined to selectively heat water molecules in a mixture of water and a cleaning solvent having a boiling point lower than water,
pound capacity dry cleaning washer, a 50 pound solvent recovery drying tumbler, a solvent still, filtering system, muck cooker, carbon adsorber solvent recovery unit, a BHP high pressure boiler, water cooling system, 100 pound laundry washer, 100 pound extractor, 100 pound dryer, water softener, water storage tank, water heater and a multiplicity of supplies and controls. It further eliminates the costs of installation and maintenance of these components.
Another important object of this invention is the provision of a cleaning method which enables apparatus of this invention to be compact, light-weight and portable,
thereby accommodating use on vehicles for door-todoor processing of residential, commercial and industrial goods, and as portable units for direct use in sections or floors of hospitals, hotels, motels and other similar establishments.
Still another object of this invention is the provision of method and apparatus by which all types of clothing and the like may be cleaned at about one-third the current cost of laundering or dry cleaning supplies and with all of the benefits of both laundering and dry cleaning, for'example, maximum removal of waterborne soils, spots and stains and whiteness retention of laundering, and the removal of oil base stains with avoidance of wrinkling, shrinking, color fading or bleeding and loss of surface protective additives of dry cleaning, with equipment of about one-tenth the cost.
Another objective of this invention is the provision of a cleaning method and apparatus in which the water content of the solvent mixture is recovered by distillation and the distilled water reused, thereby eliminating the costs of large volumes of water and water softeners and the problems of disposal of the waste, as presently involved in conventional laundering.
A further objectof this invention is to provide a cleaning method and apparatus by which to achieve sterilization of fabrics contemporaneously with their cleaning. v I
A still further object of this invention is the provision of a cleaning method and'apparatuswhichis characterized bythe production of sterile organic and inorganic waste capable of use as a fertilizer.
A further object of this invention is the provision of acleaning method and apparatus in which the cleaning solvent isrecovered for reuse after each cleaning cycle by distillation under conditions of minimum heating, whereby to minimize the production of deleterious de composition products fromthe solvent, I g It is a general object; of this invention to provide a method-of separating 'the lower boiling point constituent of a mixture by selectively heating the higher boiling point constituent, whereby the latterjtransfers its heat to the lower boiling point constituent to effect vaporization of the latter.
The foregoing and other objects and advantages of this invention will appear from the following detailed description taken in connection with the accompanying drawing of a preferred embodiment.
BRIEF DESCRIPTION or THE DRAWING DESCRIPTION OF THE PREFERRED EMBODIMENT The cleaning apparatus illustrated diagrammatically in the drawing includes a hollow housing 10 in which a clothes-containing tub 12 is mounted for rotation on a horizontal axis, by means of 'a shaft 14 coupled to an speed type, whereby to accommodate rotation of the tub at slow speed during the washing'portion of the cycle and at higher speed for the spin drying portion of the cycle, as will be understood.
The front of the housing is provided with an opening 18 (FIG. 2), removably closed by a hinged door 20, for gaining access to the tub. Suitable seal means 22 is provided between the door and housing to provide a substantially vapor tight sea]. In the preferred embodiment illustrated the seal means comprises an annular resillent ring secured to the door and arranged to abut the exterior of the housing outwardly of the edge 18 defining the opening l8,for purposes explained more fully hereinafter.
"Within the housing there is a solvent level sensing switch 24, for example of the float type, to control the maximum level of cleaning solvent in the housing, Additionally, the housing also may contain a relative humidity sensor- 26 for controlling the termination of the drying portion of the cycle and the addition of an'optithereof.:-lnterm'ediate the ends of the drain pipe is a drain control valve 30 for opening andclosing the pipe. The lower end of the drain pipe extends through the top wall 32 of'a distillation container 34 and terminates at its lower end slightly above the bottom wall 36 of the container. r v I I ln the preferred embodiment illustrated, the distillation container overlies and is integral with a solvent storage container 38, the top wall of which is formed by the bottom wall 36 of the distillation container.
The upper end-of a solvent fill pipe 40 communicates with the housing through the bottom wall thereof, and .the lower end of the pipe terminates adjacent the bottom wall of the solvent storage container 38. A fill control valve 42 is interposed in the till pipe intermediate the ends thereof.
The' upper end of a'sludge cleanout pipe 44 communicates withthe interior of the distillation container through the bottom wall thereof and extends outward therefrom. A'control valve 46 is associated with the sludge cleanout pipe. l
Thedistillation container'and solvent storagechamber preferably are interconnected adjacent their upper ends through a connecting pipe 48 and interposed control valve 50, for purposes explained in detail hereinafter.
- An air inlet pipe 52 communicates withthe interior of the housing and .is provided with a control valve 54 for controlling the admittance of air into the housing, as explained hereinafter.
An elongated condensate trap 56 communicates at its lower end with the interior of the distillation container through the top wall thereof. The condensate trap extends vertically upward and is closed at its upper end. A vapor inlet pipe 58 extends radially through the wall of the condensate trap adjacent the upper end thereof and is bent upwardly within the condensate trap to terminate adjacent the closed upper end thereof. This arrangement insures against the admittance of condensed and solid materials into the vapor inlet pipe. v
The opposite end of the inlet pipe communicates with the inlet of a conventional circulating pump 60,
v 4 preferably of the positive displacement type. The outlet of the pump communicates through an outlet pipe 62 with a refrigeration condenser 64, preferably of the conventional two-temperature type. in this regard, refrigerant infeed and return tubes 66 and 68 connect the two stages of the condenser to a compressor unit 70. The heat radiator of the compressor is connected through tube 72 and valve 74 to the portion of the coil in the lower stage of the condenser, for defrost purposes, in conventional manner. An expansion valve 76 in the infeed tube 66 prevents flow of hot gases back through said tube.
The bottom of the condenser communicates through a condensate return pipe 78 with the upper end of the solvent storage container 38. lf desired, a branch pipe 78 from the return pipe may communicate with one or more auxiliary supply containers 80 each through a control valve 82. The auxiliary containers may serve as storage for such additives as soap, detergent, fabric" whitener, water proofing, moth proofing, fire retardent, water and others. It will be understood that the additive containers will be pressurized, by any conventional means, in order to introduce the additives to the return pipe 78 which is pressurized by the circulating pump.
A vent inletpipe 84 communicates at its lower end i with the interior of the condenser through the top thereof and includes a safety bleed control valve 86. The upper end of the vent pipe communicates with the interior of a solvent extraction-tower 88-through the bottom thereof. The tower is filled with particles of activated charcoal or other material which functionsto adsorb cleaning solvent which may be contained in the vapor leaving the condenser. A vent outlet pipe 90 communicates with the interior of the tower through the top thereof and is provided with a check valve 92 which functions to open the pipe to the atmosphere for venting air from the system, but does not allow atmospheric air to enter the pipe. The check valve thus is adjusted to open at a pressure above atmospheric but below the pressure set for the safety bleed control valve Means is provided for recovering the solvent vapor adsorbed on the material in the tower 88. Thus, a cooling and heating coil 94 in the tower communicates at its infeed endthrough tube 96 and expansion valve 98 with the refrigerant infeed tube 66 and selectively through tube 100 and valve 102 with the hot gas infeed tube 72. The return end of the coil 94 communicates through tube 104 with return tube 68. Periodically, as explained hereinafter, the valve 102 is adjusted to circulate hot gases from the compressor radiator through the coil 94, to. release the solvent vapors. At other times, refrigerant is circulated through the coil 94, through tube 96 and valve 98, to cool the adsorbent material in the tower.
A solvent vapor bypass pipe 106 communicates at one end with the upper end of the tower and at the opposite end with the vapor inlet pipe 58. A control valve 108 is provided in the bypass pipe for opening and closing the latter.
A pressure relief pipe 110 communicates at one end with the interior of the housing, above the level of cleaning sosution, and at the opposite end with the vapor inlet pipe 58. A control valve 112 is provided in the pressure relief pipe for opening and closing the latter.
In accordance with this invention, the recovery and refining of the cleaning solution is accomplished by means of microwave radiant energyv For this purpose a microwave generator 114 of conventional design is utilized to provide the desired frequency, as explained hereinafter. The output of the generator is connected, by means of a selector switch 116, either through a flexible conductor 118 to a radiating head 120 mounted in the door 20 of the housing, or through a conductor 122 to a radiating head 124 mounted in the distillation container 34. I
The operation of the apparatus described hereinbefore, and hence the method of this invention, is as follows:
The door 20 of the housing is opened, clothes or other materials to be cleaned are deposited in the tub l2, and the door reclosed. All of the control valves are closed, with the exception of the drain control valve 30 and air inlet control valve 54. The tub drive motor 16 and circulating pump 60 then are activated. It will be understood that the compressor 70 will have been activated earlier to chill the condensor system.
As the clothes tumble in the tub, any loose dirt, lint and other loose debris gravitate downward through the drain pipe 28 into the distillation chamber 34. This is aided by the slight sub-atmospheric pressure in the distillation chamber resulting from operation of the chem lating pump. Thus, air from the housing, with entrained particles of debris, is bubbled through cleaning solution container in the distillation chamber from the rinse portion of'the preceding cycle. The particles of debris are trapped in the solution, while the air passes on through the circulating pump. Use of the solution in the distillation container to trap solid debris, eliminates the necessity of conventional filters in the system, and the attendant disadvantages of periodic cleaning or replacement.
The vapor output from the pump pressurizes the condenser 64 and solvent storage chamber 38. When the pressure exceeds the value set on the safety bleed valve 86, the latter opens and allows vapor to pass upward through the extraction tower 88 where any solvent vapor is collectedon the adsorbent material contained therein. The remaining clean air is exhausted through check valve 92 to the atmosphere.
After a short period of time, for example A minute, during which the clothes in the tub have tumbled adequately to release loos'e debris and the circulating pump has pressurized the solvent storage chamber 38, the drain control valve 30 and air inlet control valve 54 are closed and the fill control valve 42 and pressure relief control valve 112 are opened. Clean solution thus is forced upward through the fill pipe 40 into the housing 10 to the level established by the level control switch 24. The slightly elevated pressure in the housing, resulting from the admission of cleaning solution thereto, is relieved through the pressure relief pipe 110 to the inlet pipe 58 of the circulating pump.
The cleaning solution comprises a mixture of a minor proportion of water and a major proportion of cleaning solvent having a boiling point lower than water. One such solvent is trichlorotrifluoroethane as previously mentioned. The amount of water in the mixture may be varied over a substantial range, depending in part upon the amount of water-borne soils in the materials to be cleaned. The water may be added directly, or from aqueous solutions of additives such as those enumerated hereinbefore. In general, the water content may vary from about 1 percent to about 10 percent, and preferably is maintained at about 4 percent, of the cleaning solution. It will be understood that the'cleaning solution also may contain one or more additives, such as those enumerated hereinbefore.
Simultaneously with the filling of the housing, the microwave generator 114 is energized and the selector switch 116 operated to direct microwave energy from the head 124 into the distillation chamber 34 in which is contained dirty rinse solution from the prior cleansing cycle, as previously mentioned.
Since the cleaning solution contains a proportion of water, the frequency of microwave energy is chosen to be preferentially absorbed by the water. At least two such frequencies are known for water; namely, 950 mhz and 2,450 mhz. At these frequencies the water molecules are caused to be heated preferentially without materially heating the solvent molecules directly. However, the heated water molecules transfer heat to the solvent molecules. Accordingly, since the boiling point of water is greater than the boiling point of the solvent, th'elatter ultimately vapo'rizes in the distillation chamber.
The solvent vapor passes upward through the condensate trap 56 and thence through the vapor inlet pipe 58 to the circulating pump 60, from whence it is delivered to the refrigeration condenser 64. The solvent vapors are condensed to liquid form and returned through the pipe 78 to the refined solution storage container 38.
In the event the safety bleed valve 86 opens to relieve excessive pressure in the condenser, all solvent content of the vapor is adsorbed on the activated charcoal or other appropriate material in the tower 88. The remaining clean, dry and sterile air passes through the check valve 92 to the atmosphere.
When distillation of the solvent is complete, continued application of microwave radiant energy results in distillation of the water content of the solution. The resulting water vapor is drawn through the circulating pump to the condenser, where it is collected in frozen form. Accordingly, the valve 74 is opened periodically to defrost the condenser coil, whereupon the liquified, distilled water is returned to the storage container 38 for reuse. This arrangement thus eliminates the need for water softeners and also overcomes the cost and depend in part upon the amount of solvent and water 7 to be distilled in a desired length of time.
Dlstillation of the dirty rinse solvent and water in the distillation chamber 34 continues during the wash cycle following filling of the housing with solvent and closure of the fill control valve 42. The wash cycle may involve, for example, five minutes or so.
When the distillation is completed and the micro wave energy to the distillation chamber is cut off, valve 102 is adjusted to communicate hot gas tube 72 with infeed tube 100 of tower coil 94, and vapor bypass control valve 108 is opened, for example for about 1 minute, to release'solvent vapor from the activated charcoal or other appropriate material in the tower and return it through the circulation pump 60 and condenser 64 to the storage container 38.
Upon completion of the washing portion of the cycle, the pressure relief valve 112 is closed and the drain control valve 30 is opened to discharge the cleaning slutionfrom the housing 10 to the distillation container 34, with the aid of the slight sub-atmospheric pressure in the latter, as previously mentioned. Simultaneously, the speed of the tub drive motor 16 is increased to effect extraction of solution from the clothing. This extraction portion of the cycle involves, for example, about one to one and one-half minutes, whereupon the drain valve is: closed, the fill and pressure relief control valves are opened and the tub drive motor speed is reduced to normal washing speed.
' The housing thus is once again filled with clean solution for rinsing the clothes. During this rinsing portion of the cycle, which involves about minutes, microwave energy is again delivered to the distillation chamber 34 to effect'distilla tion of the dirty solution just received therein following the preceding washing portion of the cycle. Followingthe rinse portion of the cycle, the pressure relief valve 112 is closed and the drain control valve 30 is opened todischarge the rinse solution from the housing to the now empty distillation chamber. Simultaneously therewith the tub'drive motor is increased to extraction speed, for about one to 1% minutes, and thereafter reduced to regular speed to allow continued tumbling of the clothes.
(ioncurrently with reductionof the tub drive 'motor to washing-speed, the microwave generator 114 is activated and the selector switch 116 is moved to direct microwave energy to the head 120 mounted on the door 20 of the housing. The tumbling clothes thus are caused to fall downward through the field of microwave energy, whereupon the latter effects heating of the water molecules in the solution remaining in theclothes. As explained hereinbefore, the heated water molecules transfer heat to the solvent molecules to effect-vaporization of the latter, while the clothes remain substantially unheated.
The i'ield of radiation of microwave energy may be I tion of the water also isvaporized following complete vaporization of the solvent. The vaporized solvent and water are drawn into the distillation chamber by virtue of the slight sub-atmospheric pressure in the latter resulting from operation of the circulating pump.
When the moisture content in the housing is reduced to a pre-determined value, as established by the relative humidity sensor 26, the associated switch operates to activate the tub air inlet valve 54 to open the inlet pipe 52. By virtue of the slight sub-atmospheric pressure in the housing, atmospheric air is drawn into the housing, and a portion of the warmed water still retained in the clothing transfers to this incoming air. A steaming effect thus is produced on the clothes. At this time the tub motor and microwave-generator are deactivated. By removing the clothes quickly from the tub and hanging them up, they develope a wrinkle-free condition.
Periodically, following completion of distillation in the distillation chamber, the sludge control valve 46 is opened to allow gravity removal of sludge collected in the bottom of the distillation container. This sludge inciudes dirt, lint and oils removed from the clothes, and residues of soap and other additives. Such gravity removal of sludge is facilitated by the retained excess water, rendering the sludge fluid, as explained hereinbefore. Removal also may be assisted by opening the valve 50 to pressurize the distillation chamber from the elevated pressure in the storage container 38.
Since the sludge is subjected to microwave radiation in the distillation chamber, it is sterilized before re moval. Accordingly, it may be utilized safely as a garden fertilizer.
it is to be noted that the use of microwave energy in drying the tumbling materials provides the added advantage of sterilizing the materials contemporaneously with their cleaning.'This renders the present invention particularly advantageous for use in hospitals. To insure a sterile exit for the cleaned and sterilized materials from the housing, the seal 22 (FIG. 2) is spaced outwardly of the edge 18 defining the housing opening 18. Accordingly, the exteriorsurface of the housing between the edge 18' and the seal 22 is subjected to microwa've radiation and, is thus sterilized in the same manner as the interior of the housing and the contents thereof. v
The use of microwave radiant energy in the tub l2 offers an alternative meansfor measuring and controlling relative humidity in the housing,. in place of the sensor 26. j
. Still another advantage attending the use of microwave radiant energy in the tub and distillation chamber,'resides in its provision of minimum heating of the solvent. Thus, since the radiant energy heats only the water to the maximum temperature of its boiling point, the solvent is subjected to minimum decomposition and consequent insignificant production of corrosive or other hazardous compounds whichmight damage the I equipment or be toxic-to the h'uman'body. Thisrenders the method and apparatus of this invention practicable for coin-operated, do-it-yourself use. Further, microwave energy insures complete removal of solvent from thick articles such as clothes, paddings, sleeping bags, stuffed toys and others which thus may be cleaned quickly and safely by the method and apparatus of this invention.
It is to be noted that during the entire cleaning cycle the housing 10 is maintained at a slight subatmospheric pressure, by operation of the circulating pump 60. Accordingly, whatever leakage might occur in the housing is always inward, and therefore'substantially no solvent vapors are lost from the closed system. This factor minimizes the cost 'of cleaning, since solvent replacement-is minimal. Accordingly, the process may be utilized in place of conventional laundering or dry cleaning, with all of the attendant advantages of both, but at considerable cost savings and elimination of pol lution factors, as discussed hereinbefore; Further, the process may be utilized with complete safety in the presence of open flame and incandescent metals, since no solvent vapor is exhausted to the atmosphere.
It will be understood that the foregoing sequence of operations of the cleaning cycle may be controlled automatically, by appropriate use of electrical timers and sensors in association with electrically actuated valves, in manner well known in the art.
It will be further understood that, although the apparatus herein illustrated includes a horizontally rotatable tub, the tub may be stationary and means, such as vertically or horizontally oscillating vanes, or ultrasonic generator means, may be utilized to effect relative motion between the clothes and cleaning solution. Further, in the drying of the clothes the latter may remain stationary and the field of microwave energy moved relative thereto. In any case, it is desirable to provide relative motion between the clothes and microwave energy in order to minimize the development of localized heating of the clothes.
The apparatus of this invention is of simplified construction for economical manufacture and is relatively compact and light in weight. Accordingly, it may take the form of a portable unit capable of mounting, for example, on a'smal] low bed trailer for door-to-door use. Alternatively, it may be mounted on wheels for mobility through selected areas or floors of hospitals and the like.
Thebasic concept of this invention, which renders practicable the cleaning method and apparatus described hereinbefore, resides in the use of microwave radiant energy of a frequency predetermined to effect selective heating of the higher boiling point constituent of a mixture, with consequent transfer of such heat from the heated constituent to the lower boiling point constituent and resultant vaporization of-the latter constituent. This basic concept may be utilized in a variety of applications other than cleaning, as will be apparent.
It will be further apparent to those skilled in the art that various changes may be made in the method steps and in the size, shape, number, type and arrangement of parts of the apparatus described hereinbefore, without departing from the spirit of this invention.
Having now described my invention and the manne in which it may be used, I claim:
1. The method of cleaning fabrics and clothes, comprising a. washing the material in a closed housing in a mixture of water and a cleaning solvent having a boiling point lower than water,
b. removing a substantial proportion of the mixture from the housing and material, and
c. subjecting the material in the housing to a field of microwave energy of a frequency predetermined to effect heating substantially only of water, while moving the material and field relative one to the other, whereby the heated water content of the remaining mixture transfers heat to the solvent content of said remaining mixture and effects vaporization of said solvent.
2. The method of claim 1 including;
a. providing a closed fluid circuit including the housing, a solvent storage container, a solvent distillation container, a circulating pump and vapor condensing means,
b. after washing the material, removing to the distilla- 10,. tion container a substantial proportion of the solvent mixture from the housing and material,
c. subjecting the mixture in the distillation container to microwave energy of a frequency predetermined to effect heating substantially only of the water content of the mixture, whereby the heated water transfers heat to the solvent content of the mixture and effects vaporization of the solvent,
d. circulating the vaporized solvent from the distil|a-.
tion container through the circulating pump to the vapor condensing means, and
e. returning the condensed solvent from the vapor condensing means to the storage container.
3. The method of claim 2 including the step, after removing a substantial proportion of the solvent mixture to the distillation container and subjecting the material in the housing to said microwave energy, of removing the solvent vapor in the housing to the distillation container.
4. The method of cleaning fabrics and clothes, comprising I a. providing a closed fluid circuit including a housing for a mixture of water and a cleaning solvent having a boiling point lower than water, a tub in the housing forcontaining material to be cleaned, a storage container, a distillation container, a circulating pump and vapor condensing means,
b. filling the housing to a predetermined level with said solvent mixture from the storage container, c. washing the material in said mixture,
. removing to the distillation container a substantial proportion of the solvent mixture from the housing and material,
e. subjecting the material in the housing to a field of microwave energy of a frequency predetermined to effect heating substantially only of water, while moving the material and field relative one to the other, whereby the heated water content of the remaining mixture transfers heat to the solvent content of said remaining mixture and effects vaporization of said solvent,
f. removing the solvent vapor from the housing to the distillation container,
g. subjecting the mixture in the distillation container to microwave energy of a frequency predetermined to effect heating substantially only of the water content of the mixture, whereby the heated water transfers heat to the solvent content of the mixture and effects vaporization of the solvent,
circulating the vaporized-solvent from the distillation container through the circulating pump to the vapor condensing means, and
i. returning the condensed solvent from the vapor condensing means to the storage container.
5. The method of claim 4 including the steps, following vaporization and return of the solvent to the storage container, of subjecting at least a portion of the remaining water in the distillation container to said microwave energy to effect vaporization-of the water, circulating the vaporized water from the distillation container through the circulating pump to the vapor condensing means, and returning the condensed water from the vapor condensing means to the storage container.