US 3144872 A
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Description (OCR text may contain errors)
T. J. KEARNEY THROUGH-TYPE SOLVENT WASHER Filed Aug. 16, 1965 Aug. 18, 1964 QW 55M i- United States Patent 3,144,872 TRUGH-TYPE SLVENT WASHER Thomas J. Kearney, Detroit, Mich., assigner to Detrex Chemical industries, Inc., Detroit, Mich., a corporation of Michigan Filed Aug. 16, 1963, Ser. No. 302,686 4 Claims. (Cl. 134-72) This invention relates to an apparatus for removing soils from the surface of non-absorbent Work pieces and, in particular, to an improved Washer apparatus in which highly volatile chlorinated hydrocarbon solvents such as perchlorethylene are used in combination with structure which prevents substantial vapor loss thereby providing an economically feasible cleaning system.
Vapor-type dcgreasers commonly employ a vaporizing chamber to boil the solvent and a vapor zone through which the articles to be cleaned are conveyed. Such articles, while passing through the vapor zone are subjected to temperatures in the range of the boiling point,
of the solvent used. In many cases, this is not objectionable.
However, many articles or their components cannot be subjected to the boiling temperature of the solvent or a temperature in the range of 190 degrees F. to 250 degrees F. without harmful effects. Further, some soils such as lapping, buiing and dry polishing compounds become more difficult to remove after being subjected to high temperatures. In these cases, the lubricant present in the cleaning compound is removed but the insoluble residue remains making subsequent removal very difficult.
Further, in conventional vapor degreasing equipment, the work to be cleaned is often introduced through a top opening in the vapor zone and this places a restriction upon the size and contour of objects that can be degreased.
The structure of the washer of this invention overcomes the objections and limitations described above and includes novel structure and arrangement that enhances the cleaning and at the same time reduces solvent losses through the open ends of the unit. Superior cleaning is 5 A preferred form of the solvent washer of this invention having the advantages described hereinbelow, is identified generally in the drawings by the numeral 10. The washer 10 is depicted in two parts with the apparatus on the left side identified generally as the washing section 12 and that on the right side as the drying section 14. The washer 10 consists of a substantially sealed or airtight, elongated chamber 16 having an open entrance 18 and an open exit 20 at opposing ends. A slat or wire mesh, belt type continuous conveyor 22 extends the length 60 of chamber 16 around sleeves 24, the conveyor 22 being driven by power means (not shown). In general, articles or work pieces W to be cleaned are placed on the conveyor 22 at the entrance 18 and carried along progressively and in sequence into an entrance vestibule 26, a rst spraying zone 28, a spray rinse zone 30, a distillate spray rinse zone 32, a drain zone 34, a blow off or drying zone 36 and nally through the exit vestibule 3S to the exit 20 at which point the articles are removed from the conveyor 22.
In more detail, the preferred form of cleaning appa- 3,144,872 Patented Aug. 18, 1964 ICC ratus of this invention comprises a sump 40, containing a reservoir of a high volatile, chlorinated hydrocarbon solvent such as perchlorethylene, positioned adjacent the front of chamber 16. A sump pump 42 driven by motor 43 and fed by conduit 44 withdraws solvent from the sump 40 and discharges the solvent through conduit 45 into a series of spray pipes 46 and discharge nozzles 47. The discharge nozzles 47 are arranged to spray the solvent from all directions on the work piece W (shown in broken lines) passing along on the conveyor 22. The pressure created by pump 42 and the volume of solvent passing through conduit 45 is suicient to discharge a high pressure solvent spray all over the work piece and thus insure good cleaning. After the solvent has dissolved and otherwise removed soils from the work piece, the solvent falls onto drip pans 48, shown in broken lines :and also in solid lines in the cutaway portion of the drawing. The solvent thereafter flows into settling tank Sil and, after it reaches a sufficient level, passes over baffle 52 whereby it returns to sump 40 for further discharge by pump 42. If desired, an automatic filler 54 can be used to remove the insolubles from the settling tank 50, retaining the solids within the iilter and returning the pure solvent to sump 40.
A bafed approach zone 56 is located between the entrance 18 and the first spraying zone 28 so as to deflect any ricochet of fluid sprayed from the discharge nozzles 47.
An entrance solvent recovery apparatus, generally designated by the numeral 60, is located adjacent the entrance 18 and collects atomized vapors from the first spray zone 28 and thereby prevents the vaporized solvent from leaving the front of chamber 16. The solvent vapor recovery apparatus 60 comprises an exhaust plenum 62 into which the solvent-laden air is drawn by an exhaust fan 64 through a conduit 63. The arrows in the drawing indicate the direction of flow of the vapor. A condenser 66 having a condensing medium flowing in a coil 68, acts to condense the vapors and pass them through return conduit 69 to the sump 40. The condensing medium is cold water but can also be chemical coolant in a refrigerator unit. The solvent-laden air stream, originally taken in through plenum 62, after it has given up substantially the vapor solvent, is returned through duct 7i) to vestibule 26.
By virtue of the articles passing through the vigorous spray in zone 28, the majority of the soils, soluble and insoluble, have been removed. To insure complete soil removal, the article Wa is carried by the conveyor 22 through a spray rinse zone 3i). In this zone, the same or similar solvent is held in a separate sump 74 and supplied to a series of discharge pipes 78 and discharge nozzles 79 by a pump 75, a motor 76 and a conduit 77. The discharge nozzles 79 are arranged to spray solvent to all points on the surface of the work piece on the conveyor. After flowing over the article, the solvent returns to sump 74 for reuse.
As the article progresses forward through the chamber 1 6 on'the conveyor, it is subjected to a distilled solvent r1nse 1n zone 32. The solvent distillate is supplied by a solvent still 80 which is of the conventional type havlng heating and condensing coils (not shown). Solvent, only slightly contaminated by soluble soils, is withdrawn from sump 74 through a conduit 82 by a pump 84 which delivers the solvent when required to still 80 by conduit 86. The distillate from the still 80 passes through conduit 87 to a discharge nozzle88 providing the article Wc with the rinse of pure distilled solvent. The drain or offal of this rinse falls on plate 89 and is 0 returned to sump 74.
It should be clear that additional cleaning is attained by use of still 80. Resulting from a high distillate rate,
the entire solvent contents of sump 74 can be re-distilled two or three times per hour thus reducing its contamination to a minium and assisting greatly in producing a high degree of cleanliness on the article passing through the washer.
After passing through the distillate rinse in zone 32, the article moves through drain zone 34 which allows the draining distillate to flow along shed plate 89 to sump 74.
The cleaned article is then carried on the conveyor into the latter part of the washing apparatus and into a blow-off or drying zone 36 where all traces of the solvent are removed from the articles identified by the numeral Wd. In drying zone 36, heated air is discharged over the articles through a series of nozzles 90 connected to a pair of plenum chambers 92 which are fed by a supply duct 94. The heated air, after it has absorbed or evaporated the solvent, is exhausted from the blow-off zone 36 through a series of openings 96 Within the top of the chamber 16 and into an exhaust duct 98 by means of suction created by an exhaust fan 100. The fan discharges the solvent-laden air into coil housings 102 which has a series of coils 104 mounted therein. A cooling medium passing into coil inlets 106, through the coils 104 and from the outlets 108 thereby condenses a major part of the solvent vapors present in the air ilowing through housings 102. The condensate drops to the bottom of the housings 102 and through drain 110 where it is conducted to sump 74.
The air just denuded of solvent is conducted by duct 112 around heating coils 114 having steam inlets 116 and steam condensate outlets 118. From this point, the heated air passes into supply duct 94 and is recirculated through the drying zone 36.
The cleaned and dryed article Wf passes along the conveyor to the exit vestibule where a second solvent recovery apparatus 120, similar to apparatus 60 associated with the entrance vestibule, is positioned. The exit solvent recovery apparatus 120, as only partly shown, comprises an exhaust plenum 122, a duct 124, a suction fan 126 and a returned duct 128. As in the entrance vapor recovery apparatus, the air ows in the direction of the arrows and the solvent vapor recovered from the air adjacent the open end of the chamber 16 is condensed and returned to sump 74.
The washing apparatus described herein is specially designed to use highly volatile chlorinated hydrocarbon solvents without losing substantial amounts of the solvent by evaporation. By means of a re-circulating blow-off and recovery system, the lm of solvent normally adhering to the surface of the article after washing is vaporized by the hot drying air and then removed from the air stream continuously by the condensation action of the cooling coils. At the entrance and exit openings of the apparatus, the solvent that would normally escape to the atmosphere as vapor is captured by a more than adequate exhaust system which collects and passes the captured solvent-laden air over condensing and cooling coils, returning the condensate to the sump and the denuded air into the vestibule. The recircled drying air together with the vapor recovery apparatus in both vestibules substantially prevents the escape of solvent vapors into the surrounding atmosphere. By so doing, the economy of the system is preserved and health hazards' are eliminated.
Although this invention has been described with reference to specific forms and embodiments thereof, it will be apparent to those skilled in the art that various changes other than those referred to above may be made in the form of the apparatus, that equivalent elements may be substituted for those illustrated in the drawings, that parts may be reversed, and that certain features of the invention may be used to advantage independently of the use of other features, or within the spirit and scope of the invention as defined in the appended claims.
Having described my invention, I claim:
1. A through-type volatile solvent washer for removing soils from the surface of non-absorbent articles, said washer comprising:
a substantially air-tight treatment chamber having an in let and an exit,
a continuous conveyor extending the length of the chamber for transporting articles through the treatment zone,
a first spraying zone having means for discharging a chlorinated hydrocarbon solvent from a plurality of discharge nozzles on articles located on the conveyor,
a second spraying zone located adjacent said first zone and having means for discharging said solvent on the articles on the conveyor after the articles have passed through the rst spraying zone,
a distillate rinse zone located adjacent said second spraying zone and having means for discharging a distillate of the solvent on the articles on the conveyor after the articles have passed through the second spraying zone,
a blow-off zone located adjacent said distillate rinse zone and having means for discharging heated air on the articles as they pass on the conveyor, said means including an exhaust fan, a distillation apparatus whereby vapor solvent is condensed from the heated air after it is passed over the articles and means for returning said condensed solvent for subsequent spraying use, and
a pair of vapor solvent recovering means located adjacent both ends of the chamber whereby solventladen air is withdrawn from the ends of the chamber and the solvent distilled from the air for re-use in the spraying zone.
2. The washer as defined in claim 1 wherein a solvent sump is provided with a settling tank, said tank having an overow wall and a lter whereby solid materials are withdrawn from the solvent.
3. The washer as dened in claim 1 wherein the vapor solvent recovery means comprises a plenum located adjacent an end opening in the chamber, an exhaust fan and a vapor condenser whereby vapor-laden air is withdrawn from within and adjacent the ends of the chamber and thereafter the solvent condensed for reuse.
4. A through-type volatile solvent washer for removing soils from the surface of non-absorbent articles, said washer comprising:
a substantially air tight treatment chamber having an inlet and exit, a continuous conveyor extending the length of the chamber transporting articles therethrough,
a rst spraying zone having associated therewith a sump of chlorinated hydrocarbon solvent, a solvent pump, a conduit and solvent discharge means for spraying solvent on articles passing through the first spraying zone on the conveyor,
a vestibule located between the chamber inlet and the rst spraying zone,
solvent vapor recovery means associated with said vestibule, said means having an exhaust plenum, an exhaust fan connected to the plenum, a vapor condenser connected to the fan for condensing the solvent vapor into liquid solvent, a conduit connecting the condenser to the sump and an air conduit for returning the extracted air to the entrance vestibule,
a drying zone having means for discharging heated air on the articles after they have passed through the spraying zone, said means comprising an exhaust fan sucking the vapor laden air from the drying chamber, a vapor condenser connected to the exhaust fan whereby the vapor solvent is condensed to liquid solvent, an conduit connecting the condenser to the sump, means for heating the air passing out of the condenser and a supply conduit conis condensed to liquid solvent, a conduit connected necting the air heating means to the drying zone so to the condenser and the sump for returning the that the solvent denuded heated air is returned to solvent for reuse and a conduit for returning the the drying zone, solvent-free air to the exit chamber.
an exit vestibule located between the drying zone 5 and the chamber exit, and Refel'ellcs Cited in the file Of thiS patent second solvent vapor recovery means associated with UNITED STATES PATENTS said exit vestibule, said means having an exhaust plenum connected to the exit vestibule, an exhaust lsrgtijtl 21? fan connected to the exhaust plenum, a vapor con- 10 698:627 Kearney Jan. 4, 1955 denser connected to the fan whereby solvent vapor