US2316491A - Gas handling apparatus - Google Patents

Description

April 1943- R. R. TEICHNER 2,316,491

GAS HANDLING APPARATUS Filed Oct. 7, 1939 INVE/V r01? R. R. TEICHNER A TTORIVEY Patented Apr. 13, 1943 GAS HANDLING APPARATUS Rudolph R. Teiclmer, Jackson Heights, N. Y., assignol to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application October 7, 1939, Serial No. 298,392

6 Claims.

This invention relates to gas handling apparatus, and more particularly to air purifying means as applied in a booth or the like for spray painting.

Painting or other coating procedures with an air brush or similar device for spraying a coating means in liquid form, are ordinarily carried on in a spray booth having space closed in by three vertical walls, a roof and a bottom, with one veriical side open through which the spraying is carried on. Means are usually provided to exhaust air from the booth and thereby to create an indraft through the open side to prevent emission of fumes, spray and the like and also to remove these from the booth. Furthermore, means are also usually provided to form a downrunning curtain or film of water on the vertical walls of the booth to further collect and absorb spray, fumes and the like and remove them from the working space as well as to prevent their accumulation on the walls.

An object of the present invention is to provide a system of means to remove spray, fumes and the like from a spray booth by the use of air currents and water curtains together with new and improved means to separate particularly the air used from its burden.

With the above and other objects in view, the invention may be embodied in means to separate a gas, such as air, from a burden of entrained impurities, which means comprises an unobstructed passageway of varying cross-section through which the gas passes in one direction while a sheet or film of liquid flows in another direction along a varyingly oriented wall of the passage.

Other objects and features of the invention will appear from the following detailed description of one embodiment thereof, taken in connection with the accompanying drawing in which Fig. 1 is a view in side elevation, with portions broken away, of a spray booth constructed in accordance with the invention;

Fig. 2 is a fragmentary sectional detail somewhat enlarged n the line 22 of Fig. 1;

Fig. 3 is a fragmentary sectional detail somewhat enlarged on the line 3-3 of Fig. 1; and

Fig. 4 is a fragmentary partial view in end elevation showing the front of the base portion of the booth.

The embodiment of the invention herein disclosed is a completely unitary or self contained booth for spray painting relatively small objects, and which, according to size, may be set on a suitable bench, trestle, or the like, or may stand on a floor. The booth has two identically similar side walls, the nearer one in Fig. 1 being'indicated by the number 29. Between these side walls is the working space proper, open in front (at the left in Fig. l) and closed at the rear by a back wall 2|.

In all the following the observer is assumed to be standing at the left of Fig. 1, and facing toward the right, looking into the booth.

The working space merges below, without any intervening floor or septum into a tank, generally indicated at 22, ordinarily containing a supply of water. A turntable 23 to support articles to be sprayed is suitably arranged in the working space. The working space is closed at the top by a suitable roof or ceiling {member 24 which also serves to support an electric motor 25 which drives an exhaust fan 26, here shown as exhausting into the open air above the booth through an opening 21, but which ordinarily discharges into a stack.

The fan 26 draws air, through a flexible antivibration sleeve 28, from an air box 29 mounted on the rear of the top of the booth. The box 29 communicates through a set of separator baflles 30 with a vertical passageway 3| immediately behind the rear wall 2| of the booth. The rear and side walls of the passageway 3| may well present plane inner surfaces. The front wall of the passageway, however, as herein disclosed, comprises a sheet member 32 extending across the passage from side to side, and slanting rearwardly and downwardly from its upper portion, curving down, at 33, and slanting again forwardly and downwardly to the wall 2|. The bottom of the wall 2| is continued in a curve to the rear, as at 34, and then horizontally. Then it curves upwardly at 35, and slants upwardly and forwardly, as at 36, to its vertical part 2| somewhat below the bottom edge of the member 32.

The top of the member 32 is horizontal for a short distance out from its contact with the wall 2| to where it curves down into its first slanting portion. A horizontal water pipe 31 runs across the passage from side to side a little above and parallel to this horizontal shelf, and is provided with a number of perforations from which water is distributed along the shelf and thence flows down in a film over the whole member 32. At 33 a part of this film will drip off and fall straight down in a curtain of drops uponthe portion 36 below. The rest of the water film runs on along the surface of the member 32 to its end, down the wall 2| and back over the portion 36, to drop off at the curve 35.

The rear wall 2| of the working space is slanted back, as at 38, near its top and secured under the shelf of the member 32. A vertical sheet 39 is fastened along its lower part to the wall 2| so that the wall portion 38 and the sheet 39 define a water trough ill of V-shaped cross-section extending across the wall 2| from side to side. The top edge of the sheet 39 is rolled inwardly, as at 4|, making a lip for the forward side of the trough. The sheet I2I, which is in effect an extension of the wall 2I upwardly, has its lower edge spaced from the lip 4|. Water is fed into the trough 40 through one or more feed pipes 42 ending well below the lip 4|. Flat bailie plates 43 are mounted on each pipe 42 and extend completely across the trough 40 from front to rear. Each baiiie extends also along the trough a sufficient distance, as shown at I43 in connection with a similar bafile. so that water from the pipes 42 will have lost substantially all turbulence before rising past the bailies. Thus the water overflows the lip 4| in a smooth, unbroken film over the entire length of the lip and runs down over the front face of the entire rear wall 2| likewise in a smooth and unbroken film or curtain.

Each side wall is provided, in similar manner, with a trough I having a curled lip I4I, baffles I43 and water feed pipes I42, to provide a film or curtain of water flowing continuously down over the inside face of each side wall.

In all such spray booths where a curtain or film of water running down over the walls is used to collect and carry away spray debris, a secondary but nevertheless important problem is to ensure a complete and even coverage of the wall surface by the running film, which in turn requires that the water be delivered over the top edge of the wall surface in an unbroken sheet of continuously and substantially uniform thickness. If this delivery be not uniform, the water running down will tend to gather into streams separated by dry areas and the purpose of the water flhn is defeated.

Hence the troughs 40 and I40 and their modes of construction and operation in detail embody a subsidiary invention, dependent upon the main invention, whose purpose is to deliver water from the supply pipes 42 and I42 to form a continuous substantially uniform, downfiowing film on the walls 2I and 20. Characterizing features are the baflles 43 and I43 and the incurved lip M or I4I over which the water changes direction gradually from horizontal downwardly as in the case of the trough 40, or even overhangingly downwardly as in the case of the trough I40, without being forced or even allowed to lose adhesive contact with the wall surface.

The bottom of the booth is formed by the trough 22 whose side walls are, in effect, continuations of the walls 20 and whose rear wall is a continuation of the rear wall of the passageway 3|. The bottom of the trough is closed by a floor, but its top is open. Water running down the various walls of the booth will accumulate in the trough and is pumped thence back to the pipes 31, 42 and I42 by a motor pump unit 44 which draws from a suction 45 positioned transversely in the trough below the normal water level 46.

A filtering screen or septum 41 extends entirely across the trough, from side to side and front to back, somewhat below the normal water level and above the intake pipe 45. As here shown, a woven wire or otherwise meshed or multiperforate metal sheet 48 is stretched across from wall to wall and secured, as by welding, soldering or the like, to suitable supports on the walls. A suitably sized rectangle 49 of cloth, tough filter paper, fine meshed wire screen or the like is laid on and supported by the sheet 46, and may be easily removed and cleaned or exchanged for a like clean filter sheet as desired.

A float chamber 50 is secured on the outside of the right hand wall of the trough, partly below the waterline 46 and communicates with the interior of the trough only through a pipe BI entering the trough below the screen 41 to deliver clean water only to the tank. A float and lever 52 inside the chamber 50 controls a valve 53 also within the chamber to admit water thereto and thus through the pipe 5| to the trough whenever the water in the trough drops below Ihe level 46. The valve 53 is fed through a hand valve 54 and a pipe 55 from a T 56 connected through a pipe 51 to any convenient pressure supply of water. The trough may be filled rapidly to commence operations or as desired through the pipe 51 and valve 58. An overflow or drain pipe 59 may be connected to any convenient sewer or drain, and leads from a T 60 and thence via a pipe 6| from an outlet 62 in the wall of the trough above the level 46. An outlet 63 at the bottom of the trough leads via a valve 64 to the T 60 and drain pipe 59, and may be used to empty the trough when desired.

In normal operation the trough 22 is full of water up to the level 46. This water is drawn by the motor pump 44 from below the screen 41 and delivered to the pipes 31, 42 and I42 through adjustable control valves 65 and 66, respectively. The water runs down over the side and rear walls as described. The water running down the side walls flows directly into the trough 22 through the screen 41 and so back to the pump 44.

At the same time the fan 26 is drawing a considerable volume of air in through the open front of the booth, down between the water surface 46 and the bottom curve 34 of the back wall and up through the passageway 3|, through the eliminator baffles 30, and into the air box 29, whence the air is expelled through the fan and the opening 21 into the open.

The water running down over the back wall follows the curve 34 more or less, but either falls off before it has travelled very far on the curve or is torn oiI by the relatively powerful current of air passing under the curve. Likewise a goodly portion of the water running down over the portron 36 of the passage wall falls or is torn off by the air at the curve 35. The water thus coming off the curves 34 and 35 is more or less atomized and mixed with and carried along by the air current and washes the air with which it is mixed clean of both suspended paint spray and evaporated paint vehicle.

The air current thus laden with water and spray debris is compressed by passing between the surface of the water and the curve 34 and fiat 65, and may be still more compressed by its further passage between the convexity of the curve 35 and the back wall of the passage, for the parts 34, 35 and 36 are so proportioned that the cross-sectional area through which the air current is drawn in passing the curve 35 is preferably less than and in any event not substantially greater than that between the surface 46 of the water and the flat portion 65 of the bent back wall 2I between 34 and 35. On passing the curve 35, the air expands abruptly along the slope 36. In so doing a strong degree of turbulence is produced in the air, still more effectively washing the air with its carried along water. At the same time, the speed of the air current i greatly diminished and it drops most of its burden of mechanically entrained water which carries down with it the greater part of the paint spray residues.

With the continuing addition of water to the air at 34 and 35 and the redeposit of most of this water on 36, together with the water continually running down over 36 from the pipe 31, a condition of equilibrium is attained at which only a part of the water from 35 is carried up again by the air, the rest falling into the trough along with part of the water from 34 to pass through the filter 41, and, when thus cleaned, to be recirculated by the pump 44.

The air rising past 36 is again compressed and forced to speed up by the slope 66, and is again filled with mechanically entrained and more or less atomized water at the curve 33. The air is then again thoroughly mixed by the turbulence and deposits its burden of water in expanding again along the slope 32. Finally the air passes up through the eliminator baflies 30, which remove the last traces of entrained water, and is exhausted at 21.

It will be found that, when the various crosssections of the air passage are suitably proportioned, and when the air velocity is properly gauged, and when the rates of delivery of water to the pipes 31, 42 and I42 are properly adjusted, air delivered from the baifles 30 is substantially free from any admixture of paint spray residues whatever, whether solid particles of pigment or vapors of evaporated paint vehicle. In fact, in one instance the upper planes of the baffles 30 and the inside surfaces of the box 29 showed neither dust of any kind nor moisture after a considerable period of operation. Hence in many instances the bafiies may be dispensed with, as the air will be substantially completely cleaned before it arrives at them.

Although no moisture will be deposited in the box 29, the air will nevertheless carry a considerable charge of evaporated water out through the fan. Such loss of water from the circulation system described will be made up by the action of the float and lever 52 on the valve 53.

The embodiment of the invention herein disclosed is merely illustrative and may be modified and varied in many ways without departing from the spirit and scope of the invention as pointed out in and limited solely by the appended claims.

What is claimed is:

1. In a spray booth having vertical walls, means to deliver a liquid to one of the walls to form a continuous film of substantially uniform thickness to run down over a front surface of the wall, the said means comprising a trough extending horizontally along the top edge of the wall on the rear side thereof, the top edge of the wall forming a lip for the trough, a liquid supply pipe extending down into the trough to deliver liquid thereinto below the level of the lip, and a platelike horizontal baffle surrounding the pipe at a level above the outlet of the pipe and below the top of the trough.

2. In a spray booth having vertical walls, means to deliver a liquid to one of the walls to form a continuous film of substantially uniform thickness to run down over a front surface of the wall, the said means comprising a trough extending horizontally along the top edge of the wall on the rear side thereof, the top portion of the wall being curled backwardly to form a lip for the trough, a liquid supply pipe extending down into the trough to deliver liquid thereinto below the level of the lip, and a platelike horizontal bafile surrounding the pipe at a level above the outlet of the pipe and below the top of the trough.

3. Apparatus to separate a gas from impurities,

which apparatus comprises means defining an upwardly extending passageway of cross-sectional area varying along the length thereof, there being a plurality ofdiminutions of crosssectional area each followed by an enlargement of cross-sectional area to produce a plurality of compressions and subsequent expansions in a current of gas passing therethrough, means to create a current of gas to be cleaned upwardly through the passageway, and means to create a film of liquid flowing downwardly over a surface of the passageway, which surface varies along the direction of fiow of the liquid both as to amount and direction of slope to cause the gas to carry away liquid from the wall as spray where compressed.

4. Apparatus to separate a gas from impurities, which apparatus comprises walls defining an upwardly extending passageway, one of the said walls varying both as to amount and direction of slope along the length of the passageway to make the cross-sectional area of the passageway vary along the length thereof, there being a plurality of diminutions of cross-sectional area each followed by an enlargement of cross-sectional area to produce a plurality of compressions and subsequent expansions in a current of gas passing therethrough, means to create a film of liquid flowing downwardly over the said varyingly sloping wall, and means to create a current of gas to be cleaned upwardly through the passageway.

5. Apparatus to separate a gas from impurities, which apparatus comprises means to create a current of gas to be cleaned, walls defining an upwardly extending passageway through which the current of gas to be cleaned fiows upwardly, the said walls being so formed that the passageway will comprise a plurality of successive narrowings and widenings to alternately compress and expand the gas flowing therethrough, and means to create a film of liquid flowing downwardly over one of the walls within the passageway, the parts being so proportioned and arranged that the upwardly fiowing gas will carry away a portion of the downwardly flowing liquid from the wall as spray where the gas is compressed and release its burden of liquid spray where the gas is expanded, and the passageway being otherwise substantially free from obstruction.

6. Apparatus to separate a gas from impurities, which apparatus comprises means to create a current of gas to be cleaned, walls defining an upwardly extending passageway through which the current of gas to be cleaned flows upwardly, one of said walls varying in both amount and direction of slope along the length thereof to alternately approach to and recede from the opposite walls a plurality of times so that the passageway will comprise a plurality of successive narrowings and widenings to alternately compress and expand the gas flowing therethrough, and means to create a film of liquid flowing down over the surface of the varyingly sloping wall within the passageway, the parts being so proportioned and arranged that the upwardly fiowing gas will carry away a portion of the downwardly flowing liquid from the wall as spray where the gas is compressed and release its burden of liquid spray where the gas is expanded, and the passageway being otherwise substantially free from obstruction.

RUDOLPH R. 'IEICHNER.

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