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09.191991. ' D. B, BANKS Em 2,996,914 APPARATUS FOR DISLODGING FILTER CAKE FROM FILTERS Filedvoct. 2, 1935 4 sheets-sheet 1 ' Och 19, 1937- D. B. BANKS er A1. 2,096,314 >APPARATUS FOR DISLODGING FILTER CAKE FROM FILTERS ' Filed Oct. 2, 1955 F/G‘. 2. 4 Sheets-Sheet 2 Oct.~ 19, 1937. D. B. BANKS Er Al. v 2,096,314 APPARATUS FOR DISLODGING FILTER CÀKE FROM FILTERS Filed Oct. `2, 1935 . 4 Sheets-Sheet 3 o¢1.19,1937. ~ ' D, B BANKS ETAL 2,096,314 APPARATUS FOR DISLODGING FILTER CAKE FROM FILTERS Filed Oct. 2, 1935 4 Sheets-5h68# 4 Patented Oct. 19, 1937 2,096,314 UNITED STATES PATENT OFFICE 2,096,314 APPARATUS FOR DISLODGING FILTER CAKE FROM FILTERS Daniel B. Banks, Drexel Hill, and Paul D. Barton, Merìon, Pa., assignors to Sun Oil Company, Philadelphia, Pa., a. corporation of New Jersey Application october 2, 1935, serial No. 43,170 ' 1c claims. (o1. 21o-20o) In an application filed by us November 26, 1934, Serial No. 754,714, we disclose a filteringv apparatus which is especially adapted to filter precipitated wax from mineral oil. In that ap 5 paratus a number of annular trays are arranged, one above another, Within a tower. Each tray comprises a filtering section, a wash section and a filter-cake removal section. The mixture of -oil and wax is admitted'to- the ñltering sections 10 of the trays; and a washing liquid is admitted to the washing sections of the> trays. A number of sets of ñlter leaves is arranged circumferen tially over each tray. The sets of ñlter leaves are rotated together so that each set passes suc ' cessively through a filtering section, a washing section and a filter-cake removing section. A vacuum is applied to the filter leaves while‘they are in the filtering and washing sections of the trays. When a set of ñlter leaves is in the filter cake removing section of a tray, gas under pres sure is applied to` said leaves in order to dis lodge therefrom the wax that was previously de posited thereon while such leaves were passing through the filtering section of such tray. . given time in communication with the gas blow opening of the stationary valve member. Com municati‘on begins, of course, as soon as the ad 'vance edge of a channel passes beyond the near edge-of the blow opening in the stationary valve member and such communication is maintained until the rear edge of the rotating channel passes beyond the rear edge of the blow opening. The ) gas blowing operation, therefore, involves a grad ually increasing flow of gas followed by a maxi 10 mum gas flow vfollowed by a gradually decreas ing-flow of gas. While the operation is effective, with a suñî cient gas pressure, to blow the ñlter cakes olf the ñlter, it is open to certain serious objec 15 tions. 'I’he gradual application of the gas pres sure does not establish the ideal condition re quired to completely dislodge the wax, some of which tends to tightly adhere to the filter leaves. Further, the duration of the gas flow through 20 each rotating channel is prolonged, and the flow through successive channels is-almost continu ous, since the disconnection of one rotary chan ble hollow vertical shaft extends along the axis nel with the gas inflow is almost immediately followed by connection of the next rotary chan 25 nel of the series with the gas flow. Further, of the tower. Within this shaft is a number of the pressure of the gas must be maintained at ' In the apparatus of said application, a revolu vertical collecting pipes, arranged around the a high value to insure the approximately com axis of the shaft and rotating bodily with thel plete removal of the wax cake- from the ñlter 30 shaft, having mechanical and fluid-channel con leaves. The expense involved in an almost con 30 nection with the filter leaves so `thatl the latter rotate with the shaft and pipes and so that tinuous flow of gas under high pressure is a serious factor of operating costs. In a propane dewaxing plant, the most desirable gas to use means are afforded for passage of filtrate and wash'liquid from each set of filter leaves to a _ is propane and the cost of condensing the propane corresponding pipe and for passage of gas un gas used in the cake-removing operation is very 35 der pressure from each pipe to the correspond considerable. ing set of filter leaves of each tray. These pipes, bodily rotatable, as stated, with the shaft, com municate, at their lower ends, with vertically ex We have discovered that the most effective way to apply the gas pressure is to apply it in the tending channels formed in a valve member that rotates with the shaft. These channels may be, and substantiallyare, mere continuations of the short duration. The blast must, therefore, be 40 released after the channels in the two valve members are in complete register. Such opera tion is not only eifective to completely remove the wax cakefrom the filter leaves, but the vol ume of gas required is much reduced and the 45 gas pressure may also be permissively reduced. The object of our invention is to provide a reliable means to enable the gas pressure to be so applied. Another object of the invention is 50 to provide means whereby the'precise time of application of the gas pressure may be prede termined as desired and whereby, also, the dura. tion of the gas ñow may be predetermined as de 'aired` pipes. They open at their ‘lower ends through the base of the rotary valve member and are 45 adapted, in the rotation of the valve memben'to successively communicate with a. filtrate out let, a wash fluid outlet and a gas inlet or blow opening, all formed in a stationary valve member the top of which is pressed upward against the 50 base of the rotary valve member. The two out lets named are connected with a source of vacu um. The blow opening is connected with a supply of gas under pressure. In the voperation of the apparatus only one channel of the rotary valve member is at any x form of a sudden blast of maximum volume and 2 2,096,314 A preferred embodimentofl the invention is shown in the accompanying drawings, wherein.: Fig. 1 is a diagrammatic view of the means for supplying successive blasts of fllter cake dis rays; the photo-electric> cell controlling the oper ation of- electric and mechanical means, herein after described, for charging and discharging the tank 31. lodging gas. j _ The light apertures may be formed in any 5 Fig. 2 is a vertical sectional view of the sta tionary and rotary valve members and of the "electric eye” which is operable, through means suitable devices which rotatel with the rotating elements of the iilter. The devices that we have devised and consider preferable will now be de- - shown in Fig. l, to control thel admissionr of gas ' scribed (see Figs. 2, 4 and 5),. y 10 to the channels communicating with the filter y In our prior application above mentioned, we 10 leaves. , disclose a contrivance providing a mercury seal Fig. 31s a transverse section looking in the-.di . between the rotary and stationary valve members rection of arrows 3, 3 of Fig. 2. f to exclude admission >of air to the joint between Fig. ‘i is a transverse'section looking in the di 15 rection of the arrows 4, 4 of Fig. 2. ` Fig. 5 is an enlarged sectional view of a short section oi!l one of the annular rotary plates and of one of the apertures formed thereby for pas said members, and since we mount the devices > carrying the light apertures on this contrivance, it will be briefly described. vSurrounding and in tegral with `the stationary valve member 20 Vis a laterally and upwardly extending flange 40, to the >upper edge of which-is bolted a ring 4| support 20 The rotary valve member I0 (see Fig. 2) is pro ing a. mercury-containing J-shaped cup 42, which vided with tubulanchannels ||, which, at their. ’ extends within the deep annular groove formed by upper ends, communicate with the pipes, carried the iiange 40. A ring 43 is bolted to an annular` by the central rotary shaft of the ñltering appa flange on the rotary valve member I0 and carries ratus, through whichr the filtrate and the used a depending cylindrical sleeve 44 which extends 25 wash liquid are conveyed from the filter trays into cup 42 nearly to its bottom and well below through .the rotary filter leaves, and through the bath of mercury in the cup. ' > \ which gas under pressure is blown through the Secured to sleeve 44 is an annular ñange 45 rotary filter leaves'to dislodge the wax therefrom. to which is«bolted an annular plate 50 having The channels || at their lower ends assume the spaced apart arcuately extending slots 48 corre 30 shape or radial slots. The filtering 'elements are sponding in number to the channels ||. Resting not shown, since they form no part of the inven on the annular plate 50 is another an-nular plate tion. 5| having similar arcuately extending slots 49. 'I'he stationary valve member 20 is’provided The upper plate 5 I, is circumferentiaily adjustable sage of light to the photo-electric cell. _ with three arcuate channels, namely, a filtratev 35 outlet 2|, a wash iiuid outletd22, and a gas inlet 23, the opening‘of which is comparatively short. measured circumferentially (see Fig. 3), so that on the lower plate 5|) so as to provide light aper tures, of any desired dimensions, which will regis terwith the light rays (from the lamp 51 herein after described) at any desired equally spaced it cannot align, at any given point in the rotation , apart points in the rotation of the rotary elements, of valve member I0, with more than one chan 40. nel ||. ' ` Depending from'the base of the rotary valve member I0 is a bolt 24 having two collars 25 and 26 between which'is conñned a spring/ 21. By means of a roller bearing 28 on collar 26 the sta 45 tionary valve member 20 is supported, and spring of the filter. Plate 5| will, of course,«be so jad justed that the light apertures 4Willfregister with 40 the light rays when successive channels | | in the rotary valve member I0 register with the blow opening 23, but a liner adjustment than that is desired, since it is desirable that the blast of `gas should not be admitted to the iiow opening 2,3 and 45 2] operates to. maintain the stationary vvalve thence to a channel |`| until nearly or quite the member pressed against the rotary valve mem full width of the channel is open tothe blow ber. A cap 29 depending from the base of the. . opening. Further, it is desirable to control the v stationary valve member excludes admission; to 50 the space around the bolt and spring, of air which might possibly leak through the bearing to the ñl \trate or used wash ñuid ñow channels, 2| and 22. ¿instant of admission of the gas charge with-even more accuracy, since with different wax-bearing 50 'oils the time and duration of the wax-expulsion gas blast y'should be^ varied.- The construction The stationary valve member 20 is connected above'described enables this line control and regu to ,the yoke 32 by pins 3|, the yoke being support 5 ed from frame 33 in any suitable way that wi1l« lation to be accomplished. . The plates 50 and 5| must, of course, be held in » 1 prevent- valve member 20Lfrom turning. the fixed relation to which they are adjusted. l.Connected with the blow opening 23 of _the sta- ' ‘ Extending around ythe periphery of plate 50 is tionary valve member 26 is one end of a pipe 34 a ring 52 having >an inwardly extending lowerv whose other end /(see Fig. l) communicates with flange bolted to _plate l5|) and an inwardly 'extend-f 60 a valve chamber 35,` which is connected, through ~ ing upper ñange overhanging plate P5|) and eX a pipe 36, with a tankror chamber-31 adapted to tending over and contacting with the peripheral ` hold, under suitable pressure, say 20 pounds gage, portion of ~plate'5|. Spring/strips 53 attached to 'intermittent charges of gas, each of a volume plate 5| extend-‘over plate, 5| and ring `52and 'i 65 equal to that intended to be admitted intermit-` thence curve around and extendl under ring 52. tently to blow opening 23 for` transmission . By means of a"bolt and nut 54 each spring strip 65 through’each of the rotating channels .| | vas they may be tightened tcî hold it firmly against fring successively register, ,in the `rotation of valve `52 and thereby prevent circumferential displace `member I0, with blow opening 23. While any channel || registers with the ‘blow 70 opening 23, the precise time of admission to theA ment of the plate 5| upon plate 505. By un- f screwing the nuts on these -bolts, theßpressure' of the spring strips'53 upon plate 5| may be re 70 lieved sufficiently to permit such plate to be read the action upon a photo-electric cell of light rays justed as desired. The annular Íiange 45, sup which pass through aperturesvwhich, infthe ro y.porting plates.50 and 5|, is,` in effect, a split - tation of the rotary elements of the í-ltering appa clamping ring which is held tightly Iabout sleeve ratus, are moved successively into the path of said >41| by means of »a clamping bolt (not shown) so blow opening of the gas charge is determined by 2,096,314. l that the iixed plate 58 may be adjusted with re spect to ysleeve 44 by loosening the clamping bolt and moving the annular Iii'ange 45 as desired. 3 . thereby closing valve 15 and opening valve 38 as shown. The charge of gas in tank 31 then im mediat/ely discharges through pipes 36 and 34 Secured to ring 4I is a frame 55 upon which is into the blow opening 23 of the stationary valve ' mounted a cylinder 56 whose axis coincides with member and thence Vinto the aligning channel il "il al circumferential line extending through the light of the rotary valve member i6. Thence the' apertures 48-49. Screwed into the bottom of ' charge of gas is blown through the illter leaves cylinder 56 is a tube 62 .carrying an incandescent (not shown) that are in open communication with lamp 51. Within and between the top and bottom f channels Il and the wax dislodged therefrom. 10 of cylinder 56 are plano-convex lenses 58 which From the foregoing description, it will be un 10 converge the light rays from the lamp to a focal derstood that the charge of gas is not transmitted point within‘the light apertures 48--49 as they gradually to the filter leaves as the, mouth of a are successively brought, in the rotation~ of the channel Il, in the rotation of the rotatable ele rotatable elements of the apparatus, into register ments of the apparatus, starts to overlap the» 15 with such rays. Above the plates 50 and 5| is edge of the blow opening 23, and the charge -is positioned a photo-electric cell 59. not gradually cut oiî as the mouth of the channel Carried on frame 55 is a support 6| for electric- l is gradually closed. On the contrary, no gas is wire conduits 63 and 64`, the former having a ñex- " admitted to blow opening 23 until a predeter ible section connected with tube 62. On the top mined time aiter a channel Il starts to register 20 of conduit 64 is mounted a T conduit 85, one with the blow opening and, ordinarily, not until 20 lateral arm of which carries the photo-electric after said channel is open to said blow opening to cell 59, while the other arm is connected with the iull extent of its arcuate width. A gas blast an electric wire conduit 66 leading to a Arelay panel of maximum volume will therefore be delivered 98 (see Fig. 1_). Through the conduits described to the filter leaves suddenly and with maximum 25 extend the wires through which current is sup force, thereby insuring the - complete dislodg plied from the relay panel to the photo-electric ment of the wax from the ñlter leaves. Not only cell 59 and the lamp 51. is the wax-dislodging power of the gas thus great Connected with a source of supply of actuating ly increased, but the amount of gas required may fluid intended tol‘be introduced to the tank 31 is 30 a pipe 18 (see Fig. 1) which, through a pressure be materially reduced. In the prior apparatus the gas pressure was required to be high and reducing valve 69, communicatesv with a bulk the rate of Yñowrapid during the entire time that supply tank 1i which is under a suitable pressure, which should be the same as that desired to be applied to tank 31. A pipe 12 connects tanks 1i 35 witha valve chamber 13. A pipe 14 connects a channel- Ii was open to blow opening 23 and therefore involved the consumption of a quantity , valve chamber 13 with tank 31. Within valve chamber 35 is a valve 38 having a stem 39 extending through one wallfof a dia phragm chamber 11 and connected with a dia 40 phragm 18 within chamber 11. Within valve chamber 13 is a valve 15 having a stem 16 ex of gas materially greater than that required in the present apparatus. As soon as an aperture 48, 99 passes beyond the point of impingement of the light rays, the photo-»electric cell is rendered inactive and the circuit through solenoid 9i is opened, and valve 88 is turned to disconnect pipes 83 and 86 and Il@ connect pipe 85 with vent 86. Thereby the pres tendingthrough the other wall of the diaphragm .sure on opposite sides of f the diaphragm 18 is chamber and connected with diaphragm 18. A again balanced and spring 80 operates to close spring 80 is confined between a collar on valve valve 38 and open valve 15. The opening of valve stem 39 and a fhged abutment 19. When the 15 allowsanother charge of gas to iiow from bulk pressure is balanced on opposite sides of dia tank 1i to tank 31, which is released immediately n phragm 18, spring 80 holds valve 38 closed and 'after the rïext aperture 48, 49 moves into posi valve 15 open, allowing a charge oi' gas to enter tion to allow the light from lamp 51 to again im tank 31. TheY capacity of this tank, and, there pinge upon the photo-electric cell 59. n -fore, the volume of »gas ,admitted thereto, isfde What we claim and desire to protect by Letters termined by admitting a predetermined volume of Patent is: . ` a suitable liquid into the tank through an inlet pipe 8|. The gas capacity of the tank may be reduced by admitting more liquid totank 31 and ' may be increased by drawing oil' liquid through » 1. The combination with a iilter of a rotary valve having a rotating member and a substan tially stationary member, said rotating member having an opening communicating with the iilter, pipe 82. i said stationary member having a blow opening A three-way valve chamber 81 has a pipe con with which said opening in said rotating member nection 83 with pipe 12, a pipe connection 85 with during its rotation is adapted to register, a gas diaphragm chamber 11, and'a vent pipe 88 ywhich supply, a gas flow passage between the gas supply 60 may open to the atmosphere. On pipe 83 is a ’ and the Mblow opening, means to open the gas iiow 60 pressure reducing valve 84. In ~valve chamber 81 passage, and cooperating means on said rotating is,a valve 88 having an arm which is actuated member and said stationary member adapted at .by a solenoid 9| which is electrically connected through wires 92 with the'relay panel 38. 'I'he relay panel 98 is of conventional type and a predetermined point in the rotation of said rotating member and while its opening is in registry with said blow opening _to operate the gas need not be described. When the photo-electric ñow opening means. y " cell 59 is activated by the impingementv thereon D 2. In a filtering apparatus in which gas under ' of the light rays from Llamp 51 passing through pressure is admitted through a traveling mem a light aperture 48, 4 in plates 50, 8i, the cir ber having aY channel communicating with a cuit through solenoid .8 is cl L thereby turn illter to eiïect dislodgment therefrom of a illter ing valve 88 into the position shown in Fig. l. cake, the combination, with said channel mem 'I'his connects' pipes 83 and 85 and the pressure ber, oi' a relatively flxed member having a blow of the'gas thereby admitted to pipe 85 and the ‘ 'opening with whieh'the mouth of said channel diaphragm chamber ilexes diaphragm 18 to the during its travel is adapted to register; a gas sup right (Fig. 1) `against the action oi' spring 80, ply, a photo-electric cell, means controlled by 75 -accenna. 4 . ï _ the photo-electric cell to open said blow opening to the gas supply, and means adapted, in the travel of said member and while its channel is ,in registry with said blow opening, to activate said while said channel is in registry with said blow `opening and at a predetermined point in its' cell at a predetermined point in the travel of said '7. In' a filtering apparatus in which gas under travel, to open communication through said pipe - between said tank and the blow opening. member, whereby the time of admission of gas ’ pressure is admitted through a traveling member to said channel may be controlled. " . having a channel communicating with a filter to; 3. In a filtering apparatus in which gas under effect dislodgment therefrom of a filter cake, the pressure is'admitted through a traveling member combination, with said channel member, of a rel atively fix°ed member having a blow opening with 10 having a chan'nel communicating with a filter to effect dislodgmentr therefrom of a ,filter cake, vwhich the mouth Vof said'channel during its travel the combination, with said channel member, of a is adapted to register, a gastank adapted to re-F relatively fixed member having a blow opening ceive, hold and discharge successive 'charges of with which the mouth of said channel during its gas to 'said blow opening, means, including a 15 travelis adapted to register, a >gas supply, a source of light and a photo-electric cell, con 15 photo-electric cell, 'means controlled by the trolling the discharge of gas from the tank to photo-electric cell to open said blow opening to, the blow opening, and means moving coordinately the» gas supply, a' sourca of light and a plate with the traveling channel adaptedgwhile said traveling coordinately with said channel member channel is in registry with said blow opening and and having an aperture through which, in the at a predetermined point in its travel, to expose 20 il# 0 course of travel of said plate, and while said chan nel is in registry with the blow opening, light , said cell to the light from said source. 8. In a filtering apparatus in which gas under from said source is adapted to impinge upon said . vpressure is admitted through a traveling member cell, whereby the time of admission .of said gas 25 to said channel may be controlled. 4. In a filtering apparatus in which gas under pressure is admitted through a traveling member having a channel communicating with a filter to effect dislodgment therefrom of a filter cake, the 30 combination, with said channel member, of a relatively fixed member having a blow opening with which the mouth of said channel during its travel isadapted to register, a gas supply, a photo-electric cell, means controlled by the 35 photo-electric cell to open said blow opening to the gas supply, a source of light, plates traveling coordinately with said channel member having light apertures through which, while said chan nel is in registry with the blow opening, light 40 from said source is adapted to impinge upon said cell, said plates being relatively adjustable to vary the position in said plate of the effective light opening provided by said apertures. 5. Ina filtering apparatus in whic gas under 45 pressureL is successively admitted through a number'.fof rotating channels communicating with filters to effect dislodgment therefrom of filter cakes, the combination, withsaid rotatable having a channel communicating with a filter to effect dislodgment therefrom of a filter cake, the 25 combination, with said channel member of a rela tively flxed member having a blow opening with which the mouth of said channel during its travel is adapted to register, a gas tank adapted to re ceive, hold and.> discharge successive charges of 30 gas, a gas outflow passage from said tank to the blow opening, a gas reservoir, a gas infiow pas sage“ to said tank from said reservoir, means to open the iirst‘gas outñow passage and close the gas infiow passage and alternately therewith to 35 open cthe gas inflow `passage and;l close the gas outflow passage, devices controlling the opera-y tion of said means, and means moving coordi nately with the traveling channel adapted to con trol the operation of said devices at predetermined 40 pointsin the movement of said traveling channel. 9. In a filtering apparatus in which gas under pressure is admitted through a traveling member having a channel communicating with a filter to effect dislodgment therefrom of a filter cake, the 45 combination, with said channel member, of a relatively fixed member having a blow opening with which the mouth of said. channel during its channels, of a relatively fixed member having a travel is adapted to register, a gas tank adapted to receive, hold and discharge successive charges 50 50 blow opening wit which the mouths of said channels, lduring ' eir rotation, successively -of gas, a gas outflowvpassage from said tank ~to register, a gas supply, a yphoto-electric cell, a the blow opening, a gas reservoir, a gas infiow light“ source, means controlled by the photo-elec tric cell to open said blow opening to the gas 55 supply, an annular “plate surrounding said chan-y nels and rotatable therewith and having aper tures, correspondingnin number to the channels, through which, in the course of its rotation, and while successive channels register with the blow 60 opening, light from said source is adapted to impinge upon said cell. ’ 6. In a filtering apparatus in which gas underI pressure is admitted through a traveling member having a channel communicating with a filter to 65 -effect. dislodgment therefrom of a filter cake, the combination, with said channel member, of a relatively fixed member having a blow opening with which the mouth of said channel during its travelis adapted _to register, a gas tank, a pipe f passage to' said tank from said reservoir, valves controlling the respective passages, meanstend ing to open the valve in the second passage and 55 close the valve in the first passage, a pressure a'ctuable device adapted when actuated to open the valve in the first passage and close the vvalve in the second passage, a third passage communi-v cating with ysaid gas reservoir and said pressure actuable device„ a valve in the thirdV passage adapted in one position to open‘the, passage to» allow pressure to be transmitted to said devic'e _ and in another _position to relieve said pressure, ,means controlling the last named- valve, and 65 means moving'coordinately with -the.traveling Vchannel adapted, at ipredeterminedpoints in the travel of said channel, to control the operation of said valve-controlling means. 70 through which gas is adapted to be conveyedpfrom l0. In a, filtering apparatus in which gas under 70 said tank to said blow opening, and means, oper-` f pressure is _admitted through a traveling memben‘ ating coordinately with the traveling ,element , havinga channel communicating with a filter td j. adapted while said channel mouth is not in regis- I effect dislodgment therefrom of a filter cake,»the ter with said blow opening, to convey predeterl combination, with said-channel member, of a 75 mined charges of gas to V'said tank and adapted, relatively fixed member having a blow opening 75 5 2,096,314 with which< the mouth of said channel during its the photo-electric cell to open said blow opening travel is adapted to register, a gas tank adapted to the gas supply, a source of light, plates travel yto receive, hold and discharge successive charges ing coordinately with said channel member hav ing light apertures through which, while said of gas, a gas outñow passage from said tank to the blow opening, a gas reservoir, a gas inflow passage to said tank from said-reservoir, valves controlling the respective passages, means to open one valve and close the other and alternately therewith to open the second valve and close the ñrst valve, devices, including a photo-electric cell, 10 adapted to control the operation of said valve operating means, and means adapted, in the travel of the channel member and while it is in registry with said blow opening, to activate said cell at a predetermined point in the travel of said - member. ' 11. In a ?ilteringapparatus in which gas under pressure is successively admitted through a num ber of rotating channels communicating with ñlters to effect dislodgment therefrom of filter cakes, the combination, with said rotatable chan nels, of a relatively fixed member having'a blow opening with which the mouths of said channels, during their rotation, successively register, a gas supply, a, passage between the gas supply and the blow opening, a stationary photo-electric cell, a stationary light source, means controlled .by the photo-electric cell adapted to control the clos ing and opening of said passage, an annular plate 30 surrounding said channels and rotatable there with and having spaced apart apertures, corre sponding in number to said channels, arranged in a circumferential line intersecting the light rays channel is in registry with the blow opening, light from said source is adapted to impinge upon said cell, said plates being relatively adjustable to vary the position in said plate of the effective light opening provided by said apertures, and spring clips engaging said plates and adapted to be 10 loosened to permit said adjustment and to be made and tightened to holdA the plates in their adjusted position. 14. In a filtering apparatus in which gas under pressure is admitted through a traveling member 15 having a channel communicating with a ñlter to effect dislcdgment therefrom of a filter cake, the combination, with said channel member, of a relatively fixed member having a blow opening with which the mouth of said channel during its 20 travel is- adapted to register, a gas tank adapted to receive, hold and discharge, to said blow open ing, successive charges of gas, a gas reservoir from which successive charges of gas are supplied to said tank, and means to connect said gas tank 25 alternately with said reservoir and said blow opening. l5. In a filtering apparatus in which gas under pressure is admitted through a traveling mem ber having a channel communicating with a' 30 ñlter to effect dislcdgment therefrom of a ñlter cake, the combination, with said channel mem ber, of a relatively iixed member having a blow from the light source to the photo-electric cell, I opening with which the mouth of said channel whereby, in the rotation of said plate, said photo during its travel is 'adapted to register, a gas 35 electric 'cell is rendered alternately acti-ve and tank adapted to receive, hold and discharge, to inactive at predetermined points in the rotation said blow opening, successive charges of gas, a. of said channels. ‘ ' gas reservoir from which successive charges of 12.' In a filtering apparatus in which gas under gas are supplied to said tank, means adapted to pressure is successively admitted through a num 40 connect said gas tank alternately with s'aid res 40 ber of rotating channels communicating with ervoir and said blow opening, and means moving ñlters to effect dislcdgment therefrom of' filter ' coordinately with the traveling channel and cakes, the combination, with'said rotatable chan nels, of a relatively fixed member having a blow opening with which the mouths of said channels, during their rotation, successively register, a gas 50 adapted, at predetermined points in its travel, to> render the ñrst named means operative to effect said alternate operation. 45 16. In a iiltering apparatus in which gas under supply, a photo-electric cell, a light source, means controlled by the photo-electric cell to open said blow opening to the gas supply, two annular pressure is admitted through a traveling mem ber having a channel communicating with a iìlter- plates> surrounding said channels and rotatable therewith, said- plates each having light aper tures, corresponding in number to the number of the combination, with said channel member, of, 50 rotating channels, through which, in the course of their rotation, light from said source is 55 adapted to impinge upon said cell, said plates be ing circumferentially adjustable, one relatively to the other, to predetermine the points in their rotation whereat the photo-electric cell is actu ated by the light from said source. 13. In a ñltering apparatus in which gas under pressure is admitted through a traveling mem ber having a channel communicating with a ñlter to eiîect dislcdgment therefrom of a filter cake, the combination, with said channel mem 65 ber, of a relatively fixed member having a blow opening with which the mouth of said channel during its travel is adapted to register, a gas sup 60 ply, a photo-electric cell, means controlled by to effect dislcdgment therefrom of a iilter' cake, ~ a relatively fixed member 'having a blow open ing with which the mouth of said channel dur ing its travel is adapted to register, a gas tank adapted to receive, hold and discharge to said blow opening, successive charges of gas,-a gas 55 reservoir from which successive charges 'of gas are supplied to said tank, means, including a photo-electric cell, a source of light, and mech anism controlled thereby, adapted to connect said‘gas tank alternately with said reservoir and 60 said blow opening, and means, moving coordi nately with the travelingchannel and adapted, at predetermined points in its travel, to render said photo-electric cell alternately active and inac tive and thereby effect said alternate operation. 65 DANIEI.. B. BANKS. PAUL D. BARTON.