US 3606896 A
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' .APPARATUS FOR DEGiiEAING OBJECTS WITH VAPOR FROM A BOILING SOLVENT Filed June 27, 1969 Fig.1
nvveuroa KURT ANDERS H LM hwwm HTTORUE/S United States Patent 3,606,896 APPARATUS FOR DEGREASING OBJECTS WITH VAPOR FROM A BOILING SOLVENT Kurt Anders Holm, Skoghall, Sweden, assignor to Uddeholms Aktiebolag, Uddeholm, Sweden Filed June 27, 1969, Ser. No. 837,094 Claims priority, applic9aizoln/6sgveden, July 17, 1968,
Int. oi. B08b 3/04 U.S. Cl. 174-79 8 Claims ABSTRACT OF THE DISCLOSURE The invention relates to an apparatus for degreasing objects with vapor from a boiling solvent. The vapor condenses on the relatively cold object and the condensed solvent flows off the object, carrying with it oil and grease. The invention relates particularly to degreasing by means of vapor from chlorinated hydrocarbon, such as trichlcroethylene and tetrachloroethylene. Vapor from these solvents is considerably heavier than air, and the vapor thus forms a well-defined layer from the air lying above it in the degreasing apparatus.
In an apparatus of this type for degreasing some of the solvent is lost because the vapor from the solvent mixes with the air above. Even if the objects to be degreased are immersed in the steam and taken up extremely carefully, a loss takes place which is substantially proportional to the size of the contact surface between the vapor layer and the air above.
According to the invention it has been found that this loss of solvent can be substantially reduced if the transport means carrying the objects down into the vapor and up out of the vapor is designed so that it considerably reduces the size of the contact surface between the vapor layer and the air. The degreasing apparatus according to the invention thus comprises a container having a vapor zone, a means for boiling solvent and to introduce the vapor produced into the vapor zone, and a transport means for moving the objects down into and up out of the vapor zone, and is characterized in that the transport means consists of a cylinder rotatable about a horizontal'shaft and arranged partly in the vapor zone, the cylinder being provided along its periphery with openings in which the objects to be degreased are placed, the cylinder being so dimensioned that it takes up substantially the entire cross sectional area of the container at the level corresponding to the upper surface of the vapor zone in order to reduce the losses of solvent from the vapor zone.
In the following the invention will be further described with reference to the accompanying drawing which shows one embodiment of the apparatus according to the invention. FIG. 1 shows the apparatus seen from the side, partly in section. FIG. 2 shows the apparatus seen from above, partly in section.
The apparatus illustrated consists of a container 1 having a liquid zone 2, above this a vapor zone 3 and above this a zone 4 containing air and some solvent vapor. The zone 4 communicates via a conduit 5 with a fan to prevent solvent vapor from coming out into the working premises. Under the bottom 6 of the liquid zone is a boiling zone 7 in which liquid solvent is heated to boiling by means of heating elements 8. The vapor produced passes through a pipe 12 to the vapor zone 3. In the vapor zone is a wall 9 behind which cooling tubes 10 are arranged. The solvent vapor flows over the upper edge of the wall 9 and condenses on the cooling tubes 10. The upper edge of the wall 9 thus defines the upper surface 14 of the vapor zone.
The solvent condensed on the cooling tubes 10 flows through a pipe 11 down to the liquid zone 2. The surface 15 of the liquid zone is defined by a pipe 13 acting as an overflow through which the solvent flows down into the boiling zone 7.
The container 1 contains a cylinder 16 supported by a horizontal shaft 17 which can be rotated with the help of a motor via a gear '18. The cylinder consists of two parallel Walls 20, 21 and side 'walls 22 which give the cylinder a twelve-sided circumference. On each two side walls an opening 25 is arranged which is produced by making a rectangular opening in the Walls 20, 21, and joining these walls 20, 21 by means of walls 23, 24. The openings 25 are thus limited by four walls. The centre of the cylinder 16 is thus completely closed. So that temperature alterations shall not result in an over or under-pressure in the cylinder, the shaft 17 is provided with a longitudinal slit 26 which communicates through a channel 27 with the centre of the cylinder.
A conveyor 28 is arranged on a level with the bottom of the upper opening 25. Buckets 29 are fed forwards on the transport path, containing the objects to be degreased. The buckets are provided with lids and have walls of perforated sheet metal or netting. The buckets can be inserted in the upper opening 25 with the help of a pusher 30 which is operated via a piston rod 31 by a hydraulic or pneumatic cylinder 32. The buckets can be pushed back onto the conveyor with the help of a pusher 33 operating in the opposite direction which is operated via a piston rod 34 by a hydraulic or pneumatic cylinder 35.
The described apparatus operates in the following manner: The cylinder 16 is turned 60. The bucket with degreased objects in the upper opening 25 is pushed out onto the conveyor and a bucket with objects to be degreased is inserted in the opening 25. When the bucket reaches the vapor zone 3 solvent vapor condenses on the cold objects and the condensed solvent flows down into the liquid zone 2 carrying with it grease and oil from the objects. When the cylinder is again turned 60 the objects reach the liquid zone 2. Here, remnants of grease and oil, if any, are removed from the objects. The temperature of the liquid is preferably kept 30-5 0 below the boiling point of the solvent. At the next turn of the cylinder the objects come up into the vapor zone 3 again. Since the objects are now relatively cool, further condensation of vapor occurs on the objects, thus removing the solvent containing oil which accompanied the objects from the liquid zone 2. When the objects reach the upper position of the cylinder 16, the process is complete and they are pushed out onto the conveyor as described previously.
During the treatment the buckets 29 will be turned in a complete circle. Solvent which has collected in hollow parts of the objects will thus run out and all surfaces of the objects will be effectively cleansed.
The cylinder 16 covers practically the entire cross sectional area of the container 1 at the level where the interface 14 between the vapor and the air is situated. The remaining small interface 14 does, of course, result in a small quantity of solvent vapor mixing with the air in the zone 4 and being drawn out through the fan, but this quantity is considerably less than if the entire 'i-ce cross sectional area of the container 1 had constituted an interface between the vapor and air.
For objects which are difficult to degrease it may be advisable to rotate the cylinder 16 in reverse so that the objects are treated alternately with liquid and vapor at least twice. It is simplest if the cylinder 16 is permitted to turn two steps in one direction and one step in the opposite direction. Of course, the number of openings 25 need not be six as shown in the drawings.
What is claimed is:
1. Apparatus for degreasing objects with vapor from a boiling solvent, comprising a container having a vapor zone, means for boiling solvent to produce vapor and to introduce the vapor produced into the vapor zone, transport means for moving the objects down into and up out of the vapor zone, said transport means comprising a hollow and closed cylinder rotatable about a horizontal shaft and arranged partly in the vapor zone, said cylinder being provided along its periphery with openings in which the objects to be degreased are placed, said cylinder being so dimensioned that it takes up substantially the entire cross sectional area of the container at the level corresponding to the upper surface of the vapor zone in order to reduce the losses of solvent from the vapor zone.
2. An apparatus according to claim 1 wherein the horizontal axis of said cylinder is situated at approximately the upper surface of the vapor zone.
3. An apparatus according to claim 1, wherein said cylinder is rotatably supported on a hollow shaft, said hollow shaft being in communication with the interior of said container and with the atmosphere.
4. An apparatus for degreasing objects comprising a container having a liquid solvent reservoir adjacent the bottom thereof, means for maintaining a substantially constant liquid level within said container, solvent boiling means adjacent said container for boiling a solvent and delivering a solvent vapor into said container above the solvent liquid level, level control means in said container above the liquid level of said solvent for maintaining a vapor zone above the liquid level with a substantially constant upper level in said vapor zone, a rotatable cylinder conveyor having a plurality of substantially spaced object receiving compartments located adjacent its circumferential periphery, means rotatably supporting said cylinder conveyor in said container for rotation about a substantially horizontal axis and at a location so that the lower portion of said cylinder conveyor and the object receiving compartment located therein passes through .the vapor zone and dips into the liquid solvent, said container being disposed in closely spaced relationship with said cylinder conveyor, and said cylinder conveyor occupying substantially the entire cross sectional area of said container at the level corresponding to the upper level of the vapor zone for reducing the losses of solvent from the vapor zone, each object receiving compartment being separated from the interior of said cylinder conveyor and being opened for the replacement of objects when the compartments are oriented uppermost during the rotation of said cylinder conveyor.
5. An apparatus, as set forth in claim 4, characterized in that said level control means comprises a cooler located within said container above the solvent liquid level therein and the upper portion of said cooler being located substantially at the upper level of the vapor zone.
6. An apparatus, as set forth in claim 4, wherein said object receiving compartments are separated from the interior of said cylinder conveyor and are opened at two opposite sides, said container having openings in two opposite sides in the upper portion thereof to provide access to the receiving compartment of said cylinder conveyor located in the uppermost position within said container, and pusher means for displacing objects from the receiving compartments when they are located in the uppermost position and for displacing the objects outwardly through the openings in said container.
7. An apparatus according to claim 4, 'wherein said means for maintaining a substantially constant level of liquid solvent in said container includes an overflow conduit, said solvent boiling means comprising an extension of said container enclosing a boiling zone connected to said overflow conduit and including a vapor delivery conduit connected from said boiling zone into the container above the level of the liquid therein.
'8. An apparatus according to claim 7, wherein said level control means includes a cooler located with its uppermost portion adjacent the upper level of the vapor zone and having a connection for leading condensed solvent hacking into the lower portion of said liquid solvent reservoir.
References Cited UNITED STATES PATENTS 2,816,065 12/1957 Legler 202--170 3,106,928 10/1963 Rand 134-79 2,335,833 11/1943 Wood 24854 FOREIGN PATENTS 314,912 7/1929 Great Britain 202170 146,453 8/1954 Sweden 202l70 CHANCELLOR E. HARRIS, Primary Examiner US. Cl. X.R. 202-470