US 2681512 A
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Description (OCR text may contain errors)
June 22, 1954 FiledApril 20. 1949 TO A TM OSPHERE F. J. ARMSTRONG DRY CLEANING SYSTEM 1 SOLVENT IN STEAM IN 3 Sheets-Sheet 1L SOLVENT RECOVERY Ill 1 TO 5 TORA GE INVENTOR. FRANCIS J. ARMSTRONG V m humrg I ATTOR m s.
June 22, 1954 -F. J. ARMSTRONG 2,681,512
DRY CLEANING SYSTEM Filed April 20, 1949 a Sheets-Sheet :5
INVENTOR. v FRANCIS J. ARMSTRONG Patented June 22, 1954 DRY CLEANING SYSTEM Francis J. Armstrong, Syracuse, N. Y., assignor to United States Hoffman Machinery Corporation, New York, N. Y., a corporation of Delaware Application April 20, 1949, Serial No. 88,630
This invention relates to a low temperature dry cleaning apparatus, and more particularly to a condensing system adapted to be used and especially useful in condensing solvent vapors in such a low temperature dry cleaning process.
In the copending application of H. F. Hamlin, Serial No. 729,500, filed February 19, 1947, now Patent No. 2,573,966, a low temperature dry cleaning process is disclosed to which the method and apparatus of the present invention are particularly applicable. In accordance with the process disclosed in the Hamlin application, goods to be dry cleaned are introduced into a tumbler comprising a horizontal, cylindrical, rotatable drum having perforated walls and mounted in a casing in such manner that a non-aqueous solvent can be introduced into the casing and drum and the drum rotated to agitate the goods, thereby promoting effective contact between the goods and solvent to wash dirt and oily or greasy materials from the goods. Upon completion of the washing step, the solvent is drained from the goods, and the rotational speed of the drum is increased to an extent sufiicient to remove solvent from the goods by centrifugal force. The speed of rotation of the drum is then decreased, the casing evacuated .and residual solvent removed from the goods by bringing steam into contact with the goods under controlled conditions.
In practicing such a process it is desirable that the drying step be carried out at a relatively low temperature, e. g., 109 F. to 105 F., and since the tumbler contains liquid solvent, vapor and steam under approximately equilibrium condi tions during the drying step, the desired low temperature can be conveniently maintained by con trolling the pressure in the tumbler at a relatively low value. Various methods of controlling tumbler pressure might be used such as adjusting the steam flow to the tumbler, admitting a controlledfiow of air to the tumbler or maintaining the steam flow constant and removing the vapors from the tumbler and condensing them at a controlled rate. Of these various methods of controlling the tumbler pressure the last is preferable from the point of view of economy and eiiec'tiveness of control. However, certain problems arise in controlling the vapor condensation rate because of the low temperatures that it is desired to use.
It is apparent that if sufiicient refrigeration is used, the condensing rate may be varied as desired even at the low temperatures that are preferably employed for drying, but the use of refrigeration is expensive and for economical operation of the dry cleaning process it is necessary that less expensive cooling media, such as ordinary cooling water, be used. Moreover it is important that rapid fluctuations in the tumbler pressure be avoided and that the pressure be maintained uniformly at the desired low value. From this point of view it is desirable that a relatively small but readily controllable cooling potential be available to condense the vapors withdrawn from the tumbler and maintain the tumbler pressure in the desired manner.
Accordingly, it is an object of the present invention to provide an improved low temperature method of removing residual organic solvent from goods that have been dry cleaned with such a solvent. It is another object of the invention to provide an economical method of maintaining the pressure within a dry cleaning drier at a desired relatively low value. It is a further object of the invention to control automatically the drying step of a low temperature dry cleaning process. It is a still further object of the invention to provide apparatus for so condensing vapors from a dry cleaning drier as to maintain the drier pressure at a desired low value. Other objects of the invention will be in part obvious and in part pointed out hereafter.
The many objects and advantages of the present invention may best be appreciated by reference to the accompanying drawings which illustrate apparatus embodying the present apparatus invention and capable of being used to carry out the method of the invention. In the drawings:
Fig. l is a schematic drawing of a dry clean ing system showing a tumbler adapted to be used as a combination washer-drier, a condenser for condensing solvent vapors withdrawn. from the tumbler, and certain auxiliary equipment;
Fig. 2 is an enlarged axial section through the condenser of Fig. 1 showing the internal construction of the condenser;
Fig. 3 is a top plan view of the condenser of Fig. 2; and
Fig. 4 is a transverse section through the condenser of Fig. 2 taken on the line d-4 of Fig. 2.
Referring to the drawings and more particularly to Fig. 1, there is shown in the left-hand portion of this figure a combination washer-drier it which may be generally similar in construction to conventional tumblers used in the dry cleaning art. It comprises an outer stationary casing l2 and an inner rotatable drum l4 within which the goods are placed for cleaning. The
casing I2 is provided with a door I6 which is adapted to register with a door I8 of the rotatable drum i i to permit introduction of the goods into the drum. The casing I2 and door 5 are made air-tight to permit the interior of the easing to be evacuated, and the casing I2 is made strong enough to withstand external atmospheric pressure when the interior of the casing is highly evacuated.
The drum M comprises a perforated cylindrical shell 20, the perforated end plates 22 and 23 and the flared inlet 26 through which steam passes to the interior of the drum. The central portion of end plate 23 is imperforate, that is to say, the perforations of end plate 23 are annularly arranged near the periphery of the plate to reduce the possibility of steam passing through the drum without coming in contact with the goods in the drum. Mounted on the inner surface of the shell 20 there are spaced longitudinal ribs 26 which extend radially inward toward the center of the drum and serve to lift and tumble the goods as the drum is rotated. 7
To rotate the drum I4 a motor 23 is provided which is connected through pulley 3t, belt 32 and pulley 34 with a shaft 36 by which the drum I4 is rotated. The shaft 36 is mounted inva suitable bearing 38 and is provided with a conventional seal .40 which permits rotation of shaft 36 and at the same time prevents any substantial amount of leakage of air into the casing I2 when the casing is evacuated. The other end of drum I4 is mounted by means of the narrow portion of the flared inlet 24 in the bearings t2 and a vacuum-tight seal is provided by housing as.
Steam and solvent may be introduced into the casing I2 and drum I4 through a pipe 4% that extends through the housing 34 and the initial portion of the flared inlet 24 to substantially the point at which the wall of the flared inlet begins to diverge. Solvent is supplied to pipe 46 through a branch pipe 58 provided with a valve 50 and steam is supplied to pipe 46 through a branch pipe 52 provided with a shutoff valve and steam flow control valve 56. To remove solvent from the apparatus there is connected to the bottom of casing I2 a drain pipe 58 provided with a shutoff valve 60 and pump 62, by means of which solvent may be pumped from the casing to a solvent storage tank (not shown).
Steam and solvent vapor flow out of casing IE through a pipe 64 which is preferably connected to the casing at several spaced points as indicated in Fig. 1. Vapors are conducted through pipe as to a condenser 06, which as shown in Figs. 2, 3 and 4, is of the direct contact type and will be described hereafter in connection with those figures. Continuing now to refer to Fig. 1, cooling water is admitted to the condenser 66 through a pipe 68 and condensed solvent and water flow from the condenser through a pipe T0 to a pump I2 driven by a motor 14. A check valve II is provided in the pipe III to prevent back-flow through this pipe to the condenser. The condensate is pumped by the pump I2 through pipe 16 to a separator 18 wherein the liquid solvent and water separate from each other, the solvent forming an upper layer and the water a lower layer. Solvent is removed from the separator I3 through a pipe 30 containing a shutofi valve 82. A portion of the water from the separator 78 is returned through pipe 60 to the condenser 66 and the remainder of the water flows through an overflow pipe 34 to a sewer or other point of disposal. Fresh cooling water is supplied to the pipe 68 and thus to the condenser 65 through a pipe 86 provided with a regulating valve 88.
Connected to the top of condenser 66 by a pipe 92, containing shutoff valve 94, is a vacuum pump 9! to evacuate the tumbler I0 during the drying step. To permit venting of the system comprising the tumbler I 0 and condenser 65, pipe 92 is provided with a vent pipe 95 having a shutoff valve 98. When the system is being evacuated, valve Q8 is closed and valve 94 open whereas when the system is operating under atmospheric pressure, valve 98 is open and valve 94 closed.
In order to prevent excessive pressures from building up in the tumber I0 and to maintain the tumbler pressure at the desired value certain controls are provided and operatively connected at various points in the system. Thus the steam valve 55 is of the solenoid-operated type and is energized by a pair of conductors I95 and IE2 which are connected to a suitable source of energy. Connected in series in conductor I02 there is a vacuum switch I04 that communicates with the pressure within the casing I2 of tumbler I0. The switch I04 is normally closed during the drying operation but opens when the pressure within the casing rises above a predetermined value, say 5 inches of mercury absolute. During the period that switch I04 is closed,v the solenoid motor of steam valve 56 is energized and the valve remains open. If for any reason the pressure within casing I2 rises above the value that causes switch I04 to open, the solenoid motor is deenergized and the steam valve 56 closes. Thus the pressure within casing I2 is automatically prevented from rising to an excessive valve during the vacuum drying process.
Also connected in series with the switch I04 across the conductors I00 and I02 are a switch I06 operated by a temperature responsive element IGI located in the pipe 68 and a solenoid motor Hi8 for operating the water valve 88. The arrangement is such that while the switch I04 is closed the flow of water through pipe is determined by operation of switch I06 which is effectively a thermostat that maintains the flow of fresh cooling water through pipe 86 at such a value as to maintain the temperature of the water supplied to the condenser substantially constant. sponse to an increase in pressure in tumbler I0, solenoid motor Hi8 remains deenergized and valve 88 remains closed, thus preventing further quantities of cooling water from being supplied to pipe 68 and to the condenser 65, even though the water temperature in pipe 68 may have risen above its control value.
When the pressure within the casing I2 is sufficient to open switch I04 the condensate pump I2 is automatically stopped. The motor I4 is provided with a solenoid operated switch III] which is connected in series with the switch I04. Hence opening of the switch I04 stops motor I4 and pump I2.
As indicated above, the vapors from the tumbler I0 are condensed by being brought into direct contact with cooling water in the condenser 66, the internal structure of which is best shown in Figs. 2, 3 and 4 of the drawings. Referring to Fig. 2, the condenser 66 comprises a cylindrical casing H2 having at its lower end an integral closure plate I I4 and being provided at its upper end with a peripheral flange II6 to which the cover H8 is bolted by the nuts I20. Suspended from the cover H8 and extending down When the switch I04 opens in re-' condensing chamber.
through the casing N2 of the condenser 66 there is a cylindrical condensing chamber 122. The vapor pipe 54 is connected to the top of condensing chamber I22 in such manner that vapors flowing through the pipe '64 flow downwardly through the condensing chamber I22.
Mounted within the condensing chamber I22 there is a series of water sprays I24 that spray water into the interior of condensing chamber I22 and thereby condense vapors flowing into the The water supply pipe 68 is connected to a pipe I26 that is mounted in the cover H8 of the condenser 66 and extends down within the space I21 between the condensing chamber I22 and the wall II2 of the condenser. At its lower end pipe I26 is connected to a channel I28 which is formed adjacent the outer surface of condensing chamber I22 and communicates with the sprays I24 in such manher that water entering the condenser 66 flows through pipe we the sprays I24.
Within the lower portion of the pipe I there is a valve member I253 adapted to cooperate with a seat 32 formed in the interior of the pipe to regulate the flow of water therethrough. The valve member I] has a stem I34 that extends down through a guide I35 at the lower end of pipe I25 and engages one end of a lever I38 pivoted at I46 on the fixed support MI. The other end of lever I 33 is pivotally connected to a float hi2 that floats in a body of liquid at the bottom of the condenser 66. The arrangement is such that the float I 42 actuates valve stem I24 to open or close the valve I38 as more fully described hereafter.
The vacuum pipe 92 is connected to the top of condenser in such manner that non-condensible gases from the tumbler Iii are drawn through the condensing chamber I22, space I21 and through pipe 22 to the vacuum pump 92. At a point spaced somewhat from its lower end, the condenser 66 is provided with a liquid discharge connection I 56 which is connected to the pipe 19 (see Fig. 1) through which cooling water and condensate are drawn by the pump 12. The discharge connection I56 as shown in Fig. 2 is located somewhat above the lower rim of condensing chamber I22 so that normally a body of condensate collects in the bottom of the condenser 66. At the bottom of the condenser 55 there is a drain connection I58 through which residual liquid may be drained from the condenser.
Under certain circumstances as described below there is a tendency for an excessive pressure difference to build up between the interior of the condensing chamber I22 and the space I21 within the condenser 86. To prevent such excessive pressure differences from building up, there is provided in the wall of condensing chamber I 22 a liquid seal it comprising an open-top seal chamber I52 mounted on the exterior of the condensing chamber I22 and adapted to contain a quantity of water, and a bafiie I52 ex-' tending down into the sealing liquid in the chamber. The seal chamber IEt communicates with the interior of condensing chamber I22 through an opening his and the construction is such that the chamber I52 is continuously supplied with water from one of the sprays I24 to maintain the water level in the seal chamber even with the bottom of the opening I 18. The bafiie I52 extends down into the body of water in the seal chamber I52 to an extent sufficient to preand channel I28 to and through 6 vent flow of gas or vapor from the interior of condensing chamber I22 to the space I21 under normal circumstances but permits such a flow of gas or vapor when the pressure difference on opposite sides of the wall of the condensing chamber I22 exceeds a predetermined amount.
The operation of the apparatus shown in the drawings is largely apparent from its description. Goods to be dry cleaned are introduced into the perforated drum I I of the tumbler IE] and solvent is introduced into the casing I2 and drum I4 through pipe 48. The drum I4 is rotated to produce intimate contact between the goods and the solvent. The direction of rotation of the drum Iii is preferably reversed periodically in the usual manner to secure effective washing of the goods.
When the washing step has been completed solvent is pumped from the casing I2 by pump 62 and the speed of rotation of the drum I4 increased to cause additional solvent to be removed from the goods by centrifugal action. When such further solvent as can be removed by centrifugal action has been expressed from the goods, the speed of rotation of the drum I 2 is reduced, preferably to a speed such that the goods are reasonaioly uniformly distributed throughout the drum. Solvent inlet valve 50, solvent discharge valve as and vent valve 28 are then closed, vacuum valve 94 is opened and vacuum pump 98 is started to evacuate the system.
During this initial period of evacuation, a large volume of air passes through the condenser 68 and, if the condensate level is above the lower edge of condensing chamber I22, the air flowing downwardly through the condensing chamber will tend to force Water out of the condensing chamber and up in the space I21. The resulting drop in the water level causes float I42 to open valve I30, and water in separator 18, which is under atmospheric pressure, is drawn through pipes 68 and I26 and sprays I22 into the condensing chamber I22. Because of the large flow of air through the condensing chamber and since the condensate pump 12 is not yet in operation,
this water tends to accumulate in the space I21. Such an accumulation of water in space I21 is undesirable for a number of reasons. It produces a pressure drop between the interior of the tumbler and the vacuum pump, thereby preventing the pump from evacuating the tumbler to the desired extent. Moreover if the accumulation of water in space I21 is unchecked, water will eventually be carried over into the suction cylinder of the vacuum pump. The seal M 5 prevents such an accumulation of water in space I21. When a relatively small pressure difference has been built between chamber I22 and space 521 due to flow of water into the condenser, the liquid is blown out of the seal chamber I50 and air flows from the interior of condensing chamber I22 through the opening I43 to the space I21 and thence out through pipe 92 to the vacuum pump 90. The resulting pressure equalization causes a corresponding equalization of the liquid levels in space E21 and chamber I22 and float M2 is raised to close valve I30. Thus the seal I26 prevents excessive pressure differences from developing between the condensing chamber 22 and the space I21 and reduces the possibility of water being carried by the air stream into the suction cylinders of the vacuum pump 99.
When the pressure in tumbler casing I2 has been reduced to the control point of switch I104, the switch closes, steam valve 56 opens, pump 1-2 starts removing condensate from condenser 65 and thermostat We is energized so that it will control the water temperature in pipe 68 by adjustment of valve 83. As pump 12 removes condensate from the condenser, the liquid level in condensing chamber I22 drops and float I42 moves downwardly to open valve I30 and permit cooling water to be drawn into the condenser.
The steam flowing into the drum ill through pipe 48 vaporizes the residual solvent from the goods in the drum and the steam-solvent-vapor mixture passes to the condenser 66 where it is condensed by water sprayed from the sprays I24. Solvent and steam condensate and cooling water are pumped from the condenser 66 by the pump 12 to the separator 18 from which water is recirculated to the condenser through pipe 68. It has been found that the recirculated water in passing through pipe 19, pump E2, pipe 16, separator l8 and pipe 68 loses enough heat by radiation and convection so that when it is re-introduced into the condenser 58 it is capable of condensing substantial quantities of vapors therein.
If the pump 72 goes out of service or is incapable of handling the liquid discharge from the condenser 66, the liquid level in the condenser rises causing float M2 to rise to close valve I30 and cut off the cooling water supply. Thus the float I42 is effectively a safety device for limiting the water content of the condenser 66 and preventing the water level from building up in such manner as to cause condensate or cooling water to pass through pipe 92 to the vacuum pump 90.
From the foregoing description it is apparent that the present invention provides an improved method and apparatus for controlling the removal of residual organic solvent from goods that have been dry cleaned with such a solvent. The steam-solvent mixture is condensed by direct contact with cooling water and hence cooling water at the ordinarily available temperatures can be used to so control the pressure within the tumbler as to maintain a desired low temperature therein. Recirculation of the condensate and cooling medium provides operational stability and prevents sudden changes in the pressure within the tumbler. By recirculating the cooling medium and bringing it into direct contact with vapors to be condensed it becomes practicable to operate the condensing system with a very small temperature diiference between the cooling medium and the vapors, thus providing a relatively small cooling potential and avoiding large or rapid changes in the tumbler pressure. Moreover substantial economies in cooling water may be effected by operating in this manner.
A controlled flow of fresh cooling medium is added through pipe 86 and mixes with the recirculated cooling medium flowing in pipe 68. Thus the heat content of the cooling medium supplied to the condenser is controlled to maintain the tumbler pressure at the desired relatively low value.
It should be understood that certain oi the novel structural features described above are useful independently of the other novel structures described. For example, the vacuum switch I94 of tumbler i9 is useful in controlling the conditions under which steam is admitted to the tumbler whetherthe vapors leaving the tumbler are condensed in a spray condenser such as that specifically disclosed or whether they are con densed in a conventional surface condenser. Also steam jets may be used in place'of the vacuum pump 99 to evacuate the tumbler l and other portions of the system. Since many embodiments might be made of the present invention and since many changes might be made in the embodiment disclosed herein, it is to be understood that the foregoing description is to be interpreted as illustrative only and not in a limiting sense.
1. In a system for removing residual quantities of a dry cleaning solvent from goods that have been'dry cleaned with said solvent wherein said goods are confined in a drying chamber and exposed to the action of live steam at a reduced pressure to vaporize the solvent, the resulting solvent vapors and steam are condensed in a condenser and the resulting condensate is removed from the condenser by a pump, apparatus for controlling the operation of said system comprising, in combination, first control means for controlling the operation of said pump and second control means responsive to the pressure in said chamber and operative when said pressure drops below a predetermined value to cause said pump to be started to remove condensate from said condenser.
2. In a system for removing residual quantities of a dry cleaning solvent from goods that have been dry cleaned with said solvent wherein said goods are confined in a drying chamber and exposed to the action of live steam at a reduced pressure to vaporize the solvent, the resulting solvent vapors and steam are condensed in a condenser by being brought into direct contact with a cooling medium and the resulting condensate is removed from the condenser by a pump, apparatus for controlling the operation of said system comprising, in combination, first control means for regulating the flow of said cooling medium to said condenser, second control means responsive to the temperature of said cooling medium and adapted when energized to adjust said first control means to maintain the temperature of the cooling medium entering said con denser substantially constant and third control means responsive to the pressure within said chamber and operative when said pressure drops below a predetermined value to energize said second control means.
3. In a system for removing residual quantities of a dry cleaning solvent from goods that have been dry cleaned with said solvent wherein said goods are confined in a drying chamber and exposed to the action of live steam at a reduced pressure to vaporize the solvent, the resulting solvent vapors and steam are condensed in a con denser by being brought into direct contact with a cooling medium and the resulting condensate is removed from the condenser by a pump, apparatus for controlling the operation of said system comprising, in combination, first control means for controlling the flow of steam into said chamher, second control means for controlling the operation of said pump, third control means for controlling the flow of said cooling medium to said condenser, fourth control means responsive to the temperature of said cooling medium and adapted when energized to operate said third control means to maintain the temperature of the cooling medium entering said condenser substantially constant, fifth control means responsive to the pressure within said chamber and adapted when said pressure drops below a predetermined value to energize said first control means to cause steam to flow into said chamber, said second means to cause said pump to draw condensate late the flow of said cooling medium to said condenser.
References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Mende Oct. 29, 1901 Nash Apr. 7, 1908 Hurley et a1 Jan. 18, 1910 Bataille Apr. 1, 1924 Chapin Dec. 10, 1929 Pantenburg June 21, 1932 Number 10 Name Date Ketterer June 26, 1934 Johnson Oct. 29, 1935 Bonotto July 6, 1937 Dill Aug. 3, 1937 Kampfer Feb. 28, 1939 McDonald Apr. 23, 1940 Merriam Sept. 15, 1942 Vieira Feb. 4, 1947 OTHER REFERENCES of the Link-Belt Company.
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