US3479252A - Apparatus for the degreasing of articles by means of a solvent - Google Patents

Description

Nov. 18, 1969 HOLM ET AL 3,479,252

APPARATUS FOR THE DEGREASING OF ARTICLES BY MEANS OF A SOLVENT Filed Nov. 5, 1967 2 Sheets-Sheet 1 TO SOURCE OF SUCTION ELECTRlC HEATERS INVENTORS KUH; Anders HoLTn Rune Em HCU'ISSon BY W JJA SLKLY PNL,

ATTORNEYS NOV. 18, 1969 K HOLM ET AL 3,479,252

APPARATUS FOR THE DEGREASING 0F ARTICLES BY MEANS OF A SOLVENT Filed Nov. 5, 1967 2 Sheets-Sheet 2 Fig.2

INVENTORS kin-(3 Anders HoLm Rune Einar Hamsson BY M JWWX ma ATTORNEY United States Patent 3,479,252 APPARATUS FOR THE DEGREASING 0F ARTICLES BY MEANS OF A SOLVENT Kurt Anders Holm, Skoghall, and Rune Einar Hansson, Karlstad, Sweden, assignors to Uddeholms Aktiebolag, Uddeholm, Sweden, a company of Sweden Filed Nov. 3, 1967, Ser. No. 680,584 Claims priority, application Sweden, Nov. 14, 1966,

15,569/66 Int. Cl. B01d 3/42, 3/00 US. Cl. 202-170 4 Claims ABSTRACT OF THE DISCLOSURE The invention is concerned with an apparatus for degreasing articles by means of a boiling solvent or vapour originating therefrom. The apparatus has double walls, and cooling means are provided between said double walls. The cooling means comprise water spraying means, and means for passing ventilation air through the space defined by said double walls. Consequently, the ventilation air has the double function of withdrawing solvent vapour and cooling the wall of the apparatus.

The invention is concerned with an apparatus for the degreasing of articles by means of a solvent, preferably a chlorinated hydrocarbon, usually trichlorethylene and tetrachlorethylene. The invention is concerned not only with treating the articles with a liquid heated solvent, but also with treating the articles with the vapour of the boiling solvent, resulting in the vapour condensing on the comparatively cold articles, thus dissolving oil and fat.

An apparatus for this purpose usually contains a cooler on which the solvent vapour condenses when it has reached a certain level. The cooler usually consists of cooling tubes situated at the wall of the apparatus. An apparatus of this type also usually contains ventilation means, usually a suction slot extending around the opening through which the articles are inserted into and withdrawn from the apparatus, said suction slot communieating with a suction fan. This ventilation prevents air containing solvent vapour from leaving the apparatus.

It is the object of the invention to provide cooling means operating with a minimum of cooling water. This object is attained, according to the invention, by the space for the solvent vapour being provided with double walls, and by the cooling means comprising means for spraying water into the space between the double walls, and by the ventilation means being designed to lead the ventilation air through the space between the double walls, for cooling the water sprayed into said space.

Consequently, in the apparatus of the invention the ventilation air will serve two purposes, namely to prevent an uncontrolled outlet of solvent to the surroundings, and to cool the cooling water. The latter purpose is mainly fulfilled by the evaporation of cooling water, the water vapour thus formed being removed by the ventilation air. Therefore, the consumption of water need not exceed the quantity required by this evaporation.

The invention will now be described with reference to the accompanying drawing. FIG. 1 illustrates an embodiment of the invention. FIG. 2 illustrates another embodiment of the cooling means. 7

The apparatus of FIG. 1 contains an open top container 1 having a liquid solvent 2 in its lower portion. The solvent is heated to boil by means of electric heating elements 3. The vapour fills the central portion 4 of the apparatus. The goods to be degreased is lowered into said central portion 4.

3,479,252 Patented Nov. 18, 1969 The upper portion of the apparatus includes a spaced wall structure comprising inner and outer, spaced walls 5a and 5b and upper and lower end walls 5c and 5d. This spaced wall structure surrounds the upper portion of container 1 and extends to a level above the open top of the container to provide a space for condensing solvent vapour above the container. A vertical partition 6 is provided in the upper portion of the space between said walls, thus dividing said space into two spaces 7 and 8. The Walls 5a and 5b define a water supply sump 9 below said partition 6. The level of the water in said supply is kept constant by means of a float 13 actuating a valve 14 in a feed water pipe 15, to compensate for the water which is lost.

The inlet side of a pump 10 communicates with the water supply 9, and the outlet side of said pump communicates through a pipe 11 With nozzles 12 in the upper portion of the space 7. Consequently, spray water will flow downwards in the space 7.

This spray water meets a stream of air which has been produced by a suction fan, not illustrated, which communicates with the space 7 through a pipe 19. The air enters the space between the inner and outer walls through a slot 16 extending around the inlet opening 5e of the apparatus provided in the upper end wall 50 of the spaced wall structure, this opening 5e also being the one through which the articles to be degreased are lowered into the open top container 1. The solvent vapour which would otherwise have leaked out to the surroundings accompanies said air. The air passes down through the space 8, cooling the upper portion of the wall 5b, and then passes up through the space 7; cooling the water passing down. The moist air is sucked out through the pipe 19.

The upper level of the solvent vapour is defined by a vertical wall 18. The heavy solvent vapour flows over the upper edge of said wall, thus coming into contact with the water-cooled portion of the wall 5b. The vapour condenses on said cooled wall, and the liquid solvent flows back to the boiling zone 2 through a pipe 17, while passing through a water separator and alkalizor 20 for the removal of acid impurities.

Small quantities of water enter into the apparatus, for instance accompanying the goods to be degreased. This water produces a zone consisting of an azeotropic mixture of vapours of water and solvent, said zone being situated just above the wall 18. The height of this zone is limited by the air which is sucked in through the slot 16, thus cooling the upper portion of the wall 5b.

FIG. 2 uses the same reference characters as FIG. 1 for corresponding parts. In FIG. 2 the space defined by the double walls 5a and 5b is not divided by a partition, but the ventilation air passes straight through said space from the inlet slot 16, and is withdrawn through the tube 19, which communicates with the lower portion of said space. The cooling water is supplied through a pipe 25 to the nozzles 12 spraying out the water as fine droplets. The droplets are evaporated entirely or partially during their passage down said space. Remaining non-evapoarted water, if any, is drained off through a pipe 24. This remaining quantity of water is kept at a minimum by the supplied quantity of water being adapted to the current need of coolant. This adaption takes place, first, by the nozzles 12 being dimensioned exactly for the quantity of water corresponding to the maximal need of coolant, or for a slightly larger quantity, and, second, by the water supply being shut off when there is no need of coolant, that is when the vapour level is below the upper edge of the wall 18. This is usually the case when new cold articles have been introduced. A thermostat 21 is situated in the degreasing chamber, at the level defined by the upper edge of the wall 18. When the solvent vapour has reached this level the thermostat 21 actuates a magnetic relay 22 that opens a valve 23 in the coolant supply pipe 25.

What is claimed is:

1. In an apparatus for the degreasing of articles by means of a boiling solvent or vapour originating therefrom, the combination comprising an open top container in which the articles are placed for degreasing, liquid solvent in the lower part of said container, means for heating said liquid solvent to a boil, a spaced wall structure comprising inner and outer side walls spaced from each other and upper and lower end walls, said spaced wall structure surrounding the upper portion of said container and extending to a level above the open top of said container to provide a space for condensing solvent vapour above the top of said container and within said inner wall, an inlet through said upper end wall for air and for articles to be degreased, means providing a slot-like opening extending around the upper end of said inner wall for passing air from said inlet into the space between said inner and outer walls, means for spraying water into said space between said inner and outer walls to cool said inner wall and condense the solvent vapour flowing upwardly and out through the open top of said container, means for returning the solvent condensate into said container and means including an outlet through said outer wall for withdrawing the air from said space between said inner and. outer walls together with such solvent vapour as may reach said space above said container and be drawn into said spot-like opening along with the air and together with such water vapour as may have resulted from an evaporation of the water sprayed into said space.

2. Apparatus as defined in claim 1 for degreasing articles which further includes a partition wall located intermediate said inner and outer walls and extending longitudinally thereof, and wherein said means for spraying water into said space between said inner and outer walls comprises a pump having its intake side in communication with a sump in the lower portion of said space and its outlet side connected to spray nozzles located between said partition wall and said outer wall, said outlet for withdrawing air from said space between said spaced walls being located at a level above the lower end of said partition wall thereby to draw said air downwardly from said slot through the space between said inner wall and said partition wall and thence upwardly through the space between said partition wall and said outer Wall.

3. Apparatus as defined in claim 2 and which further includes a water supply pipe leading into said space between said inner and outer walls, a valve in said pipe, and a float in said space which controls operation of said valve to compensate for water lost by evaporation.

4. Apparatus as defined in claim 1 wherein said means for spraying water into said space between said inner and outer walls comprises spray nozzles situated at a level above the desired vapour level, said nozzles being dimensioned for a water quantity corresponding to the maximal quantity of coolant, a thermostat positioned within said container at the desired highest vapour level, pipe means for supplying water to said nozzles, and a control valve in said pipe, said valve being controlled by said thermostat.

References Cited UNITED STATES PATENTS 339,201 4/1886 Merz 202-195 1,043,305 11/1912 Duensing 202189 2,020,335 11/1935 Savage 202-170 2,243,093 5/1941 Flahive 202187 X 2,650,085 8/1953 Burnett 202189 X 2,779,723 1/1957 Prymek 202-187 X 3,011,956 12/1961 Smith et a1. 202-206 3,015,613 1/1962 Edmondson 202-l87 3,165,455 1/1965 Rose et al. 202189 3,375,177 3/1968 Rand 202170 X 3,242,057 3/ 1966 Talian et al. 202170 X FOREIGN PATENTS 657,686 2/ 1963 Canada.

NORMAN YUDKOFF, Primary Examiner F. E. DRUMMOND, Assistant Examiner US. Cl. X.R.

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