US1732086A - Gas scrubber - Google Patents

Description

Oct. l5, `1929. J, P, FLIPPEN 1,732,086

GAS scRUBBER Filed Jan. 6. 1926 2 Sheets-Sheet 1 FIELI.

WHA/6555 I l l y y.

Patented oat. 15, 1929 PATENT OFFICE JOHN Pr FLIPPEN, OF PITTSBURGH, PENNSYLVANIA GAS SCRUBBER Application filed January e, 192e. serial No. I29,544.

This invention relates to scrubbers or washers such as are ordinarily employed for removing foreign material from gaseous fluids.

An object of the invention is to produce a simple and inexpensive scrubber which is more effective in operation than scrubbers now in use and known to me. f

A further object is to produce a gas scrubber in which means are employed for maintaining the efliciency and the effectiveness of the scrubber under varying conditions of operation.

These and other objects are attained by means'of apparatus embodying the features herein described and illustrated in the drawings accompanying and forming a part hereof.

In the drawings- Figure 1 is a vertical sectional view of a scrubber embodying my invention;

Fig. 2 is a sectional view on an enlarged scale of a portion of the apparatus shown in elevation'in Fig. 1;

Fig. 3 is a plan view of a detail of the scrubber embodying my invention; and

Fig. 4 is a plan view of a segment of a grid forming a detail of the invention.

Apparatus of the character herein de- 30 scribed is ordinarily employed for the purpose of removing dust or other extraneous materials from gaseous fluids, and in this operation it is necessary to subject all the gas traversing the scrubber to the wetting and cool* ing action of a washing liquid. It is a'lso essential, from the standpoint of efficiency, to

utilize a minimum amount of washing liquid,

but under conditions that will give the desired results. For this reason, it is not only desirable but almost essential to provide means which will enable the operator or attendant to vary Ythe supply of washing liquid as the s upply of gaseous Huid to be washed varies but,

at the same time, to employ the washing liquid effectively and to minimize the amount vof power utilized during the washing operation.

Scrubbers now in` use Aemploy means for varying the amount of washing liquid employed but no means are employed in such scrubbers for compensating for varying flows of 11qu1d 1n such a way as to mamtain a minimum resistance to flow of the tus and at the same time accomplish effective scrubbing under all variations in flow of gaseous Huid. This advantageous result is attained by means of apparatus embodying my invention. As illustrated, the scrubbing apparatus set forth as a practical embodiment of my invention consists of a chamber 4 provided wit'h a gas inlet port 5, gas outlet port 6, liquid distributing devices 7 and revolving and stationary grids 8 and 9 which are located in pairs and in such relation to the liquid distributing devices that they not only supplement the scrubbing action of the liquid but insure a substantially uniform distribution of the gaseous stream traversing the scrubber so that all portions of the stream are uniformly scrubbed.

The chamber 4 is enclosed by a shell or casing 10-in which the inlet and outlet ports 5 and 6 are formed. The interior of the casing is preferably divided into two compartments by means of a specially formed baille 11 which also performs the function of collecting liquid which has been employed in the scrubbing operation in the upper of the two compartments. As illustrated, the baffle 11 is rigidly secured at its outer circumferential edge to the shell 10, which is prefer' ably cylindrical. This baie is substantially frustro-conical in shape and is provided at its upper edge with an upwardly extending y ange 12 which surrounds a central port 13 formed in thevbaie and also co-operates with the baille in forming a recept-acle for scrubbing liquid. The port 13 forms a free passage for the gas from the lower to the upper compartment of the chamber 4 and is shielded by a stationary directing ballie 14 which as illustrated may be mounted on the adjacent stationary grid 9.

As has been said, the grids 8 and 9 are located in pairs and, as illustrated, each of these grids is frustro-conical in shape and are so located that their outer edges are located above their centers or inner edges. As shown, each stationary grid is secured to the shell 10 gaseous fluid through the scrubbing apparaing grids.

by any suitable means, such for example, as an annular flange, shown in the drawings as a spider 15 rigidly secured to the shell, and having radially extending arms 15a. The inner edge of each grid 9 extends into close proximity lwith a central shaft 16 which extends centrally through the chamber 4 and on which the rotating grids 8 are mounted.

As shown, the rotating grids are of substantially the same shape and size 'as the stationary grids and are secured at their centers or inner edges .to the shaft 16 by means of spiders 17 rigidly mounted on the shaft. Each grid extends radially from the shaft to a point immediately adjacent to the shell 10 and the relation of each rotating and stationary grid forming a co-operating pair is such that all gaseous uid traversing the chamber 4 must pass through at least one of the grids ofthe pair.

As shown in the drawings, three pairs of cooperating grids are located in the upper compartment and two pairs are located inv the lower compartment of the chamber 4. It will, however, be understood that any number of such pairs may be located in each compartment.

Each compartment is also provided with a liquid distributing device 7 which as illus-4 trated is a ring surrounding the shaft 16 and provided with a plurality of delivery apertures so located as to discharge a spray or divided stream of liquid which substantially fills the compartment. As shown, each ring 7 ,-is 'substantially half the diameter of the `shell 10 and communicates with a source of liquid supply through piping 18 which is provided with suitable control valves 19. A moisture separator 20, shown in the form of a wire gauze, is located inthe upper compartment above the ring'7 of that compartment and between it and the outlet port 6.

During the operation of this'device, the shaft 16 is driven by a motor 21 at a speed depending upon the diameter of the rotat- While varying conditions may make it desirable to vary the speed of rotation of the shaft 16, I now prefer to rotate y the shaft at about 20 R. P. M. where the rotating grids are approximately eighteen feet in diameter.

The gas entering the inlet port 5 is distributed by a deflector 22 located above 'and immediately adjacent to that port and is further distributed as it passes through the grids 8 and 9 of the lowermost'pair., It will be apparent that these grids are wet by liquid issuing from the lower ring 7 and passing through the next adjacent pair of rotating and stationary grids. Consequently, the gas, in passing through each pair of cooperating grids is not only broken up into small streams but is subjected to the extended wetted surface of the grids with the lresult that the gas is thoroughly scrubbed i cooled.

I Will be apparent to those skilled in this art'that the scrubbing and cooling operation of the grids is supplemented to some extent by liquid falling through the chamber 4 and ,j that the foreign material carried by the gas is eventually collected by the liquid. even though its removal from the gasy is first accomplished by Contact with the wetted surface of one of the grids.

The gas, after having passed through the (zo-operating stationary and rotating grids of the lower compartment and through thev having passed through the spray or `massof separate streams of liquid issuing from the uppermost ring 7.

One advantage of employing two compartments is that it may be desirable, with certain gases, to employ different washing liquids or liquids of different concentration, and under such circumstances, the two compartments readily contribute to such a use of the apparatus. Another advantage is that, where the same character or quality of washing liquid is employed in each compartment, the heavier and more easily condensable vapors are collected in the lowermost compartment and may be disposed of independently of the liquid and foreign material collected in the uppermost compartment. Another advantage is that the amount of liquid employed may be conserved and used to thc best advantage 'by varying the amount delivered to one or the other of the rings, dependent upon the character of foreign ma.- terial contained in the gas Ibeing scrubbed. In most gas scrubbers employing rotary arts, there is a tendency for the scrubbing liquid to be thrownY outwardly y,toward the Ashell of the scrubbing chamber with the reedges above their centers. With thisarrangement, both the rotating and stationary grids minimize the centrifugalidisplacement of the scrubbing liquid, since the tendency for liquid deposited on a rotating grid to move outwardly across that grid is overcome, or at least materially minimized, by the fact that suchA outward movement would of necessity also be an upward movement of the liquid. Again, the shape of the stationary' grids 9 is such as to offset any slight centrifugal displacement of the liquid, which may be occasioned by the rotating grids,since liquid deposited or thrown onto the stationary grids will tend to move inwardly toward the center of the grids or in a direction opposite to the movement occasioned by centrifugal force. As a result of this arrangement of grids, the entire interior of the chamber 4 will be subjected to a substantially uniform flow of liquid, and there will be little or no tendency for the outer portions of the grids to receive more liquid than is delivered to the inner portions. From this, it will be apparent that the gas will be uniformly scrubbed even though there is a tendency for longitudinal stratification in the gas` stream traversing the chamber 4. i i

Such a tendency will, however,'be 'offset and, asa matter of fact prevented by the grids Sand 9, since they are preferably so formed as to contribute to'ua uniform distribution across the chamber of the gas traversing the chamber. This is accomplished by forming the gridsof heavy wire'gauze and by soconstructing the gauzey thaty the resistance to gaseous fiowthrough Iit will be as low as is consistent with the; provisions of the necessary scrubbing actiony of the gaseous fluid.`

As shown'in Fig. 3,'the grids are ymade up of radiating wires 23 which are so arranged that theJ gaspassages between them and the interwoven circumferential Wires 23a are not uniform radially of the disk. As shown, the smaller passages are 4located at an intermediate point of thedisk which tends'to offset the centrifugal action on the gas itself and Aalso tends toy make the resistance through i each pair of grids substantially uniform from the center to the periphery of the grid. Another advantage of this form of grid is that it not only presents a maximum wetted surface to the gas passing through it but also resists centrifugal action to which I have referred. It will be apparent that the circumferential wires in effect form barriers which will tendto check outward travel of the liquid on the rotating grids, since if any liquid is thrown outwardly by centrifugal force, some portion of such liquid will be thrown onto an adjacent circumferential wire or barrier 24 and will be broken up and redistributed by that barrier, thereby not only checking the outward movement of the liquid but rendering the liquid less susceptible to centrifugal force by reason of its reduction in mass. In addition, the frustro-conical shape tionary grid to intercept any liquid thrownl outwardly by centrifgual force before it has' moved very far toward the shell. Then, too, I

the barriers will form points of discharge, for centrifugally displaced liquid, with the result that each rotating disk will, under the influence of centrifugal force, discharge a multiplicity of sprays of liquid instead of a. single spray at its outer edge. This fact, and also the fact that each grid is inclined upwardly, contributes to the effectiveness of the scrubber, since it will be apparent that the space intervening between each pair of rotating and stationary grids Will be more or less uniformly flooded by such annular sprays issuing from the rotating grid, and that therefore,

gas moving upwardly through the co-oper' ating pairs will be subjected to a cross stream of liquid as well as to the wettedsurface of'the stationary and rotating grids.

On the other hand, the .circumferential wires 23a of the stationary vgrids'will not be so effective as barriers to the inward flow of the'liquid lalong the stationary grid, since the flow there will be much -slower'and the liquid will find' its way yalongfthe ygrid withoutbeing materially impeded by the circumferential barriers. 'It will also' be vapparent that the interweaving of the radial and circumferential wires will form a multiplicity f.

of pointson which liquid will collect, and that, therefore, the liquid droppingfrom the stationary grids will be uniformly distributed across the chamber. 5' r As shown in Fig. 1, the por`t13isl shielded by the shield 14. This prevents any substantial amount'of liquid from'the upper com"- partment entering the lower compartment and substantially all' the liquid employed in the upper compartmentl may therefore be drawn ofi' through the liquid outlet passage .24 of the upper compartment. In the lower compartment, the liquid outlet port 25 is preferably provided with an upwardly eX- tending flange 26 so that liquid will collect on the bottom of the lower compartment to a predetermined height.

One of the features of my invention is that the distance between the rotatingand stationary grids of each pair may be varied to suit the varying conditions of operation.

This is accomplished by so mounting the shaft 16 that it is capable of longitudinal or vertical adjustment, so that each rotating grid may be moved toward or away from its co-operating stationary grid. The advantage of such an arrangement is that washing liquid may be conserved during kperiods of low flow of gas to be washed, and at the same time the scrubbing may be effectively accomplished. It will be apparent that, as the rotating and stationary grids of each pair are moved together, they increase the resistance to flow of the gaseous fluid, since they in effect c0- operate to reduce the effective area of the gas delivery ports formed in each of them. It will, therefore, be apparent that an increased scrubbing action is obtained by moving the rotating and stationary grids closer together, and that, consequently, less washing liquid need be employed to accomplish the same result. From this, it follows that, as the flow of gas is reduced and as the resistance to ilow is consequently reduced, the scrubbing action may be maintained at a maximum, even though the amount of scrubbing liquid employed is reduced, by moving the rotating grids closer to their co-operating stationary grids.

In the drawings, I have illustrated a practical method of mounting the shaft 16 so that its longitudinalV adjustment may be accomplished even while the shaft is rotating. As shown, the driving shaft 28, which is shown coupled to themotor 21 in Fig. 1, is provided with a worm (not shown) which meshes with a worm wheel 29 shown in Fig. 2. The hub portion 30 of this wheel is mounted on a thrust bearing 31 and is operatively connected to the shaft 16 by means of a collar 32. Thecollar 32 is splined to the shaft 16 and the shaft is .adjustable to different positions relative thereto by means of a cap nut 33 which is screwed onto the threaded upper end of the shaft, and bears against the collar 32.

The thrust bearing 31 is preferably a roller bearing and the hub portion 30 is also preferably provided with a roller bearing 34 which is located between it and an annular fiange formed on the standard or support 35 and surrounding the shaft. The standard 35 is mounted on the shell 10.

With this arrangement, the shaft may be adjusted to different vertical positions even while it is rotating. As shown in Fig. 1, the lower end of the shaft extends into a guide bearing 36 which is protected from moisture Within the chamber 10 by means of a collar 37 mounted on the bottom of the chamber 4 and extending upwardly around the shaft 16 in telescoped relation with a downwardly extending sleeve 38 which is mounted on the supporting collar 17 of the lowermost rotating grid.

Another feature of the invention is that the circular grids 8 and 9 are preferably made up of a number of segments as shown in Fig. 4, for the purpose of simplifying the operation, assembling the scrubber and of renewing the grids. For this ipurp'ose, the shell 10 is provided with manholes 39, which are of such shape and size that the vsectors of the grids may be readily passed through them. The edges ofv each sector are rigidly secured to the supporting spider in any suitable manner, such for example as by means of bolts not shown.

While I have described the preferred embodiment of my invention, it will be apparent to those skilled in the art that various changes, additions, omissions and modifications may bemade therein without departying from the spirit and scope of the invenfor dividing the chamber into two communicating compartments, co-operating stationary and rotary grids mounted in each,,colnpartl ment in the path of gas travel therethrough, means for introducing a spray of separate liquids in each compartment in the path of gas travelvpassing therethrough, and means in each compartment for collecting and discharging liquid from said spray.

2. A as scrubber comprising a shell provided w1th a gas inlet port, a gas outlet port, a liquid inlet, a liquid outlet, and an opening for giving access to the interior thereof, a closure for said opening, a rotatable shaft extending axially through said shell, alternately arranged rotating and stationary grids located within said shell and intervening between said gas inlet and outlet ports, said rotary grids being mounted on and rotated by said shaft and each of said grids being frustro-conical in shape and made up of segmental sections of interwoven wire of such.'

size as to be removable through said opening.

3. In a gas scrubber comprising a shell'having a gas inlet port located near the bottom thereof and a gas delivery port located near the top thereof,arotatable shaft extending axially through said shell, frustro-conical grids of interwoven metal mountedon said shaft, each grid extending therefrom substantially to said shell and intervening between said ports with the outer edge of each grid located above its center, a stationary frustro-conical grid located in cooperative relation with each rotating grid and extending downwardly from said shell substantially to said shaft and means for` delivering a liquid spray downwardly through said shell.

4. In a gas scrubber comprising a shell having a gas inlet port located near the bottom thereof and a as delivery port located near the top thereogf, a rotatable shaft extending axially through said shell, frustro-conical grids of interwoven metal mounted on said shaft, each grid extending therefrom substantially to said shell and vintervening between said ports with its outer edge located above its center, -a stationary frustro-conical grid located in cooperative relation with each rotating grid and extending downwardly from said shell substantially to said shaft, mean for delivering a liquid spray downwardly through said shell and means for varying the distance between the rotary and stationary grids.

5. In a gas scrubber comprising a shell having a gas inlet port located near the bottom thereof and a gas delivery port located near the top thereof, a rotatable shaft extending axially through said shell, outwardly extending upwardly inclined woven wire grids secured to said shaft for rotary movement therewith and extending outwardly substantially v to said shell, a stationary woven wire grid mountedon said shell adjacent each of said rotary grids and extending inwardly substantially parallel therewith, means for deliver- ,ing a liquid spray above said grids and means for rotating said shaft.

In testimony whereof, I have hereunto subscribed my name this 4th day of January,

, JOHN P. FLIPPEN.

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