USRE21723E - Continuous pressure separating - Google Patents

Description

Feb'. `18, 1941. R. THOMPSON 10,121,723

CONTINUOUS PRESSURE SEPARATING DEVICE Original Filed Jan. l0, 1933 13 Sheets-Shet 1 Feb. 18, 1941. R. M. THoMPsoN Re. 21,723

COTINUOUS PRESSURE SEPARATING DEVICE Original Filed Jan. 10, 1933 13 Sheets-Sheet 2 aso 393 389 /l/ INVENTOR obefI/V. 77701224050 www ` ATTORNEY Feb. 18, 1941. R M THQMPSQN Re. 21,723

CONTINUOUSPRESSUHE SEPARATING DEVICE Original Filed Jan. l. 1955 15 Sheet-s-Sheet 5 i 6A /95 I -f ,wifi/ifi!! l [40J v' my. .s

Feb. 18, 1941. R M. THOMPSON l A Re- 21,723

Y CONTINUOUS PRESSURE SEPARATING DEVICE i original Filed Jan. 1o, 195:5 13 sheets-she@ 5 I lNvEN-roR ATTORNEY Feb. 18, 1941. y R, M THOMPSQN Re. 21,723

CONTINUOUS APRIEJSSURE. SEPARATING DEVIQCE Original Filed Jan. 10. 1933 13 Sheets-Sheet 6 31mo4@ @3% o INVENTOR Feb. 18, 1941. R. M. THOMPSON R 21,723

CONTINUOUS PRESSURE SEPRATING DEVICE l Original Filed Jan. 10. 1953 13 Sheets-Sheet 7 1N V EN TOR.

allvgeff Tompson ATTORNEY Feb. 18, 1941 R. M. THOMPSON Re- 21,723

CONTNOUS PRESSURE SEPRATING DEVICE Original Filed Jan. 10. 1933 13 Sheets-Shea?r 8 les,

INVENTOR oerf. Thompson ATTORNEY Feb. 18, 1941. R. M. THOMPSON Re 21,723

C ONTINUOUS PRESSUI'IE SEPARATING DEVICE origamall Filed Jan. 1o, 195s 13 sheets-sheet 9 INVENTOR ATTORNEY Feb. 18, 1941. R. M. THOMPSON Re- 21,723

'CONTINUOUS PRESSURE SEPARATING DEVICE Original Filed Jan. 10, 1953 15 Sheets-Sheet 10 IN VEN TOR.

l/lz Robez'i T/.Pompson ATTORNEY Feb. 18, 1941. R. M. THoMPsoN Re- 211723 CONTINUOUS PRESSURE SEPARATING DEVICE Original Filed Jan. 10, 19355 ,lsheets-'Sheet 1l I llllllflllll ooooooQGQlO0000 ssa INVENTOR ATTORNEY Feb. 18, R. M THMPSON Re. 21,723

CONTINUOUS PRESSURE SEPARATING DEVICE Original Filed Jan. l0, 1933 13 Sheets-Sheet 12 INVENTOR 2896611 M T /zompso I /34 2a@ o .1 f f l 1 my. 43 ATTORNEY Y Feb. 18, 1941. R. M. THOMPSON Re 21,723

CONTINUOUS PRESSURE SEPARATING DEVICE Original Filed Jan. 10, 19325v 13 Sheets-Sheet' l5 IIIAIIIIIIIIIIIL VIIIIIIl/II A 205 JNVENTOR gaberf". T/lompson Y ATTORNEY Reissued Feb.y 18, 1941r Re. 21,723 'y CONTINUOUS PRESSURE SEPARATING DEVICE Robert M. Thompson, Seattle,iWash., assigner to Thompson Continuously Operating Filter Press Company, a corporation of Washington Original N0. 2,112,869, dated April 5, 1938, Se-

rial No. 650,990, January 10, 1933. Application i'or reissue September 23, 1938, Serial No.

36 Claims.

My invention relates to the art of devices designed to separate uids or liquids from other fluids or liquids of greater fluidity and uids or liquids from solids.

More particularly, my invention relates to a combined press and lter press or to a press designed for continuous operation which is characterized by the development of extremely high pressures and practical and eiilcient operation. Particularly does my invention relate to simplifying and reducing the cost of the filtration or fil tration step in the industrial arts, which step at present constitutes one of the expensive operations in manufacturing. The invention in general relates to the art of filtering or filtration disclosed in Patent No. 1,778,342, issued to me October 14, 1930 and in my application, Ser, No. 509,595, Patent No. 1,997,611, issued to me April 16, 1935.

Itis common practice in the art of filtration to refer to devices designed for the separation of materials by the application of force or pressure tothe materials from without, as "presses; while devices designed for the separation of materials by' having the force or' pressure transmitted through the materials themselves as filter presses. Filter presses are usually used where the amount of solids to be separated is but a small proportion of the total mobile mass. composed of said solids and liquids in which said solids are disposed and hence the said materials are pumped into the tler press. Presses on the other hand. are used where the proportion of solid matter is much greater in relation to that oi' the liquid composing said materials to be filtered. The distinction between the two devices willdevelop clearly in the following paragraphs.

By rendering the filtering continuous, my device herein disclosed provides for utilizing the filter press principle with materials in which the solids are the predominant percentage of the material being treated. 'I'hls is lust the reverse of the common practice. Heretofore, the devices in common use for materials having only a small percentage of liquids, has been the press type rather than the illter press type. By providing for relatively excessively high pressures and fluid tight chambers and continuous discharge of cake in a filter press type of device, themachine embodying my invention herein set forth, has solved one of the difficult steps in -manufacturing processes.

In the industrial arts filtration is very often a costly item in the manufacturing process. This is due 1n part to the intermittent character of the operation of the filter devices and to the large amount of manual attention which is incident thereto. Moreover, in the filtering process there are points at which the expressed liquids are more clear than at other,4 points. The clearer liquids are usually obtained during the 'later stages of the separating process due to the fact that these liquids pass through the filtering me- 10 dium after a deposit of the retained solids on the filtering medium has accumulated, which retained solids usually forman important part of the filtering medium. The early liquids' expressed before the deposit of said solids in the 15 form of a lter on the filter cloth or medium may be cloudy. By separately drawing on the cloudy Aportion of the expressed liquid during the early stages of the filtration process, a minimum quantity of the cloudy filtrate is retained with the clear filtrate.

Objection obtains to the devices as heretofore designed in the leakage that takes place by the joints formed between the stationary parts and moving parts of the device. Also serious objec- 25 tion obtains to the friction developed between said parts. This friction results in excessive .wearing away of the filter cloth as well as other parts.

Aas heretofore in common use are not capable of this dual use. This involves the installation of bot-h devices which involves great expense as well as the loss of important floor space. l 4 4The general objects of my present invention are to overcome the objectionsr to prior devices of the nature hereinabove pointed out and to generally improve and increase the eliciency of continuous presses and filter presses, as Well as to 45` provide new means and modes of operation with new results.

Another important object of my invention is to provide an upright or substantially vertical press or filter press of this nature embodying two pend- (it)A ent press members, pivotally supported from their upper ends, between which press members the material passes while being filtered, said press members being connectedA with each other by .transverse iloatingly mountedtie means, whereby 55 the heavy pressures produced between the two press members are counterbalanced at frequent intervals or section by section without being transmitted to other or mounting parts of the frame. This tie means may include springs capable of yielding to pressure exerted between the two pendent press members.

Another object is to provide equalizer means in connection with both the top and bottom of the pendent press members for compelling equal movement of said press members toward and away from the ycentral medial vertical plane of the machine at all times, the upper equalizing means preferably being in the form of manually operated adjusting mechanism and the lower equalizing means preferably being automatically operated in response to pressure.

, Another primary object is to provide a press and iilter press of this nature having a filter 20 chamber formed by four belts, all moving in the same direction and at substantially the same rate of speed, whereby wear and needless consumption of power. due` to friction is reduced to a minimum, vand the problem of preventing leakage of liquids even under relatively excessively high as well as ordinary pressures is very much simplied, two of said belts preferably being of material impervious to the passage of liquid and being supported by resilient. means. l

A further object is to provide for the application of intermittent or periodic increase of pressure to the material being treated, whereby short drainage periods are afforded during the intervals Awhen the pressure is relatively sustained but. not increased, as well as during such periods of increasingt-he pressure. The preferred means for effecting such periodic action may be in the form of a ratchet drive for transmitting the power to the filter means, said ratchetdrive affording an 40 intermittent drive of relatively slow and readily variable speed.

Other and more specific objects are to provide eiiicient self-adjusting plug means for maintaining a substantially liquid tight contact with the 45 moving belts; to provide suction means forpicking up any liquid which escapes around the plug means; to provide new and eiiicient means for picking up or collecting the liquid filtrate after it has passed through the filter cloths and slats 5 (to prevent reabsorption of the liquid -by the solid matter (cake) during its emergence from the pressure zone) to provide types of slatmembers for slat'belts new as toform and construc- `tion, whereby the withdrawal. of itrate away 55 from the pressing face of the slats is facilitated;

to provide for employing traveling porous absorbent means as an assistance to carrying through the pressure chamber the material being treated and promoting the drainage of the uid 60 part of the material; and to provide automatic means for governing the speed and the rate of feed tothe machine in proportion to the thickness of the cake or layer of solid matter in the machine at the point of maximum pressure.

v65 'ine above mentioned general objects of my invention, together with.others inherent inA the: same, are attained by the mechanism illustrated 75 Figure 2 is a side elevation of the same.

Figure 3 is a vertical section substantially on broken line 3-3 of Fig. 2.

Figure 4` is a cross section substantially on broken line 4-4 of Fig. 3.

Figure 5 is a cross section substantially on broken line 5 5 of Fig. 3.l

Figure 6 is a detached elevation from the outer or rear side of the frame/of one of the main .pendent press members.

Figure 'l is an edge view of the same.

Figure 8 is a cross section substantially `on broken line 8 8 of Fig. 6.

Figure 9 is a detached elevation of a frame rail used to vsupport the impervious side belts of my machine.

Figure l0 is a, detached plan View of a filtrate pick-up device used in my invention.

Figure 11 is a sectional view substantially on broken line II-II of Fig. 10.

Figure 12 is a detached cross section of a cup like packing plugused in the upper portion of my pressure chamber to form a seal against the escape of liquids, a leather packing cup being shown.

Figure 13 is a fragmentary view partly in section and partly in elevation of the upper portion of my press and filter press, showing a preferred form of packing plug means in end elevation.

Figure 14 is a detail view partly in elevation and partly in longitudinal section of va preferred form of multiple packing plug used in my machine. V

Figure 15 is a cross section substantially on broken line |5-I5 of Fig. 14.

Figure 16 is an inverted fragmentary plan view of one of the packing plugs shown in Figs.' 14

and 15. l A.

Figure 17 is a fragmentary sectional view through the side belt rail and side belts, showing a fragment of the main lter belts in the position in whichthey make sealing contact with the side belts.

Figure 18 is a front elevation, with parts broken away, of one form of slat for the main slat belts, a wire mesh being used on the face of said slat.

Figure 19 is a 1sectional View on broken line l9-l9ofFig. 18.

Figure 20 is a fragmentary sectional view substantially on broken line 2li- 2n of Fig. 18 illustrating details of the drainage means of the slat shown in Figs. 18 and 19.

Figure 21 is an end view of said slat.

Figure 22 is a plan view with parts broken away of another form'of filter belt slat in which a slotted plate is used on the face of the slat.

Figure 23 is an edge view of the slat shown in Fig. 22.

Figure 24 is a sectional view substantially on broken line 24-24 of Fig. 22.

Figure 25 is a sectional View of a preferred form of filter belt slat of rhomboidal shape in cross section to afford Walls which are inclined downwardly from the face to the rear of said slat to promote drainage of liquid.

Figure 26 is a fragmentary elevation of a perforated plate which may be used on the lter belt slat shownv in Figs. 18 to 21 in place of the wire mesh plate shown in said Figs. 18 to 2l.

Figure 27 is a sectional view of still another form of filter belt slat in which said slat is of rhomboidal shape in cross section to aiford walls .which are" inclined downwardly from the face to the rear of said slat to promote drainage of a liquid, and inwhich a plat of porous -iilter ma- Figure 29 is a fragmentary cross section on.

broken line 2.-29 of Fig. 28.

Figure 30 is a sectional view on a larger scale substantially on broken line 30-30 of Fig. 28.

Figure 31 is a detached elevation illustrating one means for varying the speed oi the ratchet drive and one means for compelling an equal travel of each ratchet arm.

Figure 32 is a detached fragmentary elevation illustrating one centering means which may be used in connection with the ratchet drive.

Figure 33 is a detached fragmentary elevation of other centering means for the ratchet drive.

Figure 34 is an elevation showing means for varying either the feed of the machine or the speed of movement of the belts, or both, automatically in proportion to the thickness of the cake or body of solid matter between the iilter belts at the location where said cake'is most highly compressed.

Figure 35 shows a modified form of my invention in which the filter -belts are supported on chain mesh belts, which, in turn, are supported on rollers, the chain mesh rbelts taking the place of the slat belts shown'in the preceding figures. 'Ihis iigure also shows a movable carrier member in the nature of a very porous fabric disposed between the filter belts, said carrier member pro- Figure 39 is a cross 'section substantially on line 35-38 of Fig. 38.

Figure 40 is an enlarged detail showing the flexible means for supporting the packing plug between the four moving lter belts in such a -manner as to insure an equal pressure of the plug against all filter belts.

Figure 41 is a somewhat diagrammatic side elevation of another modied form of ratchet drive for my combined press and filter press in which the ratchet levers are connected directly to the crank arms.

Figure 42 is avfragmentary plan view of parts of a bevel gear drive which may be used for the side chains of my combined press and filter press.

Figure 43 is a view partly in section and partly in elevation showing the complete drive of the bevel gear mechanism shown partly in Fig. 4,2.

Figure 44 is a somewhat diagrammatic side elevation illustrating one means of guiding' iilter belts into my combined press and filter press.

Figure 45 is a fragmentary sectional view showing an alternative spring supporting structure for the main pendent frames. Y

Figure 46 is a cross section through a side framel of my machine showing a coil spring resiliently supporting the side belt rail, said coil spring a1'- fording greater travel and being less subject to breakage than the flat springs shown in Figs. 4 and 1'7.

Figure 47 is a somewhat diagrammatic side elevation showing a modied form of my4 invention in which one of the pendent frame members is amas these bearings.

xedly and adiustably secured at its lower end to a non-movable partof the frame.

Figure .48 is a fragmentary sectional view of a modiiied form of the invention in which the impervious moving side belts are dispensed with and a highly polished non-movable plate is substituted in place thereof. v

Figure 49v is a somewhat diagrammatic view partly insection.and partly in elevation, showing means for supporting the impervious side belt means with a pressure which varies in proportion to the pressure in the lter chamber.

Referring particularly .to Figs. 1 to 17, inclusive, wherein I have illustrated one embodiment of my invention', I show a Amain frame formed of two upright parallel, spaced apart, channel shaped side members IIB provided with base members I I I and rigidly connected at their bottom ends by a cross plate II2, see Fig'. 2. At their upper ends the side members III each have an angle bar |I3 secured thereto. These angle bars extend at right angles to the member IIU and are rigidly secured together by transverse vplates III positioned near the outer ends of thef angle bars |I3. A.' transverse angle bar IIS (Fig. 3) also extends cross wise between the top ends o1' the side frame members IIIl and cooperates with the transverse plates I I4 in rigidly connecting the two upper ends of the spaced apart side members IIII together. The angle bar IIS also provides support for .a packing plug hereinafter described. The previously described parts form a rigid stationary and substantialframe on which the apparatus hereinafter described may be mounted.

. l35 Two pendent frame members, designated gentioned in depressions H9' in plates |20' which rest slidably on brackets |20 and permit the small amount of swinging movement required by the pendent frames. I'he pivotal supports which are thus formed for the pendent frame members IIS are located near the upper ends of said frame members andiin substantially vertical alignment between upper bearings I2I and lower bearings |22, see Figs. 6 and 7, which are provided on these frame members. The upper bearings I2 lare adjustably supported from shelf like portions4 |23 at the upper ends of the pendent frames IIB by adjustable screw and nut means I 24. This makes it possible to adjust the tension of slat belts,

hereinafter described, which are supported by The pendent frames, hereinafter also called strongbacks, IIC are essentially of strong and rigid construction, designed to withstand heavy pressure. They are preferably each formed of an upright medial plate portion |25 having a relatively fiat plane inner face provided with track members |28. Reinforcing cross members' |21" of.' substantially U shaped cross section are rigidly connected with the medial plate portions |25 and extend crosswise of the rear sides thereof at spaced apart intervals. Longltudinally extending web `members |28 extend along the rear side of the medial plate portions built up of a plurality of pieces welded together,

|25 and through the cross members |21, as more clearly shown in Figs. 4, 6, 7, and 8. The medial plate portions |25 of the pendent frame members are provided with openings |23 positioned between the U shaped cross members, through which openings, liquid may be taken ofi', as hereinafter described. The .outer ends of the U shaped cross members are provided with tie rod holes |30, as more clearly shown in Figs. 6 and 8. The pendent frame members IIB, are shown as but it will be understood that they may be cast in one piece, if the use permits.

The bearing members |2| at the top ends of the pendent frames ||8 support shafts |3| and |32 upon each oi' which shafts are mounted two spaced` apart sprocket wheels |33. The lower bearing brackets |22 support shafts |34 and |35, upon each of which are mounted two spaced apart sprocket wheels |36. A greater or less number of sprocket wheels |33 and |38 maybe provided on each of the respective shafts if desired. The lower sprocket wheels |38 are keyed to the shafts |34 and |35 as shown in Fig. 5yand theupper sprocket wheels |33 may be similarly keyed to their shafts I3| and |32.

Two endless slat belts are operatively mounted on the sprocket wheels |33"\and |38 and are supported on the pendent frames ||8 in such a manner as to cooperate with other parts in forming a pressure or filter chamber |38 having as two sides the two opposed and adjacent portions of said slat belts. 'Ihis pressure or iilter chamber |38 is wider at the top and converges toward the lower end inY such a manner that material which is introduced at the top end will be subjected to increasing pressure as it moves downwardly through said chamber. The opposed portions of the slat belts which form walls of the pressure chamber |38 move downwardly in the operation of the machine.

'Ihe slat belts are formed of transverse slats designated generally by |39. 'Ihese slats are secured to link belts |40 which run on the sprocket wheels |33 and |38. The link belts |40'have rollers |4|, see Figs. 44 and 5, at the locations where the links of said belts are plvotally connected, which rollers run on the track members |26 and serve as an antifriction means for supwith drainage means whereby filtrate expelled from material within the chamber |38 may readily pass outwardly through said. slats. Several forms of these slats are shown in Figs. 18 to 30, inclusive. WhereA reference is made in this specification to top edge and bottom edge of these Islats,'it will be understood that these terms refer to the slats in the positionin which they form the filter cloth supporting means or walls of the filter chamber.l it being obvious that these slats are reversed in position as they pass around the upper and lower sets of sprocket wheels |33 and |38, respectively.

These slats have three importantfunctions; first, they form `supporting means to withstand Rollerv or ball bearings ofA cloths or belts; second, they serve tocollect and direct the liquid filtrate to a denite position; third, they serve to `drain the ltrate promptly away from the filter cloth or slat face. In every y case the cracks between the edges of adjacent slats slope downwardly and away from the filter chamber, due to the fact that the lter chamber is'slightly wedge shape or convergent from top to bottom. This slope is greatly accentuated in the rhomboidal form of slat shown inFig. 27.

The slat shown in Figs. 28, 29 and 30 is one form of slat which may be used. This type of slat may be of non-metallic material, as of hardword made liquid proof by subjecting it to a hotparafllne bath. 'I'his slat has holes |42 for the reception of suitable bolts, not shown, by which said slat may be secured to the link belts |40, The holes |42 are counterbored as at |43A on the front side of the slat for the reception of the bolt heads. This slat |39 isfurther. provided, on the side against which the filter belt is pressed, with spaced apart longitudinal grooves |44, which extend from the ends of the slat to a point near the center and are connected, by a,

transverse intersecting groove |45, with drain holes |48, which drain holes extend from face to rear of the slat and afford passageways through which filtrate may be passed through the slat, so that said filtrate may be picked up at the rear side thereof. Each groove |44 preferably has a saw kerf |41 in the bottom thereof so that if a filter cloth is pressed into the groove, the saw kerf will still afford a channel for the drainage of liquidfto the holes |48. A packingmember |48 in the nature of a thin fiat piece of resilient material, as rubber, may be secured, preferably by cementing the same,to the bottom edge of each slat. These packing members tend to pre-- vent leakage between the slats. The top edge of each slat is provided with a longitudinal recess |43 which communicates with a medially positioned transverse notch or groove |50, whereby any filtrate which enters the crack between the slats is drained to the center and discharged to the rear of the slat. 'Ihe packing members |48 and recesses |40V and |58 are more clearly shown in Fig. 30, which is on a larger scale than Fig. 28. A plurality of grooves |5| are provided in the backs of the slats for the purpose of draining, toward the center of the slat, any nltrate which may escape the other grooves and trickle down the base of the slats. The grooves |5| are inclined downwardly from outer to inner ends and are cut at any angle as illustrated in enlarged detail; Fig. 29, whereby they will form channels in which the liquid may flow toward the center of the slats. When a filter cloth is pressed, against the front side` of this slat, said cloth will be supported by the lands'or surfaces |52 between the grooves |44 and filtrate may be forced through said filter cloth into the grooves `|44 and thence disposed of to the rear of the slats.

In Figs. 18, 19, 20 'and 21 I have shown a metal slat |53 provided with internal cavities |54 having ribs |55 therebetween. The face side of the slat l53 is recessed to leave a narrow marginal Yportion |55 which projects beyond the plane common to the front edges of the ribs |55. Ther face of the slat may be formed rby a relatively the pressures which are exerted against the filter the'slat |53 to-facilitate securing the same to a l link belt. The wire mesh 51 serves as a support against vwhich nlter cloth may be pressed. Liquid nitrate which is forced through said nlter cloth presses readily through said wire mesh into the cavities |54. The front edges of the ribs |55 may be notched as at |58 and |60, so that this liquid nitrate may now from the cavities |54 to a centrailylocated discharge opening |6| and be discharged through the back wall of the slat where it is picked up by liquid nitrate pick-up mechanism, as hereinafter described. The top edge of the slat |53-has a. depression |62 therein |65 forming an edge from which liquid will tend to drip, and the bevel |64 tending to prevent this drip from running forwardly between'the slats.

' Grooves |64', having'the same purpose and function as the grooves in Figs. 28 and 29 may be provided in the rear wall of the slat |53.

- The space between the two lowermost hori-v zontal wires of the wire mesh member |51 is preferably nlled or otherwise blocked up or obstructed as shown at |66, Fig. 19, to thereby f form a lip or dam to cause the liquid nltrate to now rearwardly away from the wire mesh and to further prevent anyv residual nitrate from -running back into the nlter cloth as the slat moves away from the body of material which has just passed out of the pressure zone. A narrow ledge or dam |68' .positioned just inside of the bottom edge of the slat face |51 may be used instead of the nlling |66. Also, there may be provided a dam' |56', whereby nitrate which trickies down the screen may be maintained away from the compressed solid matter of the material being treated forming the cake and positively directed to passageways |61, providing positive isolating for nitrate from the expanding vacuum-creating cake. Experience has taught that the nitrate tends to collect in the lower meshes of the nlter face from which, unless provision such-as dam |56' is provided, itis reabsorbed into the cake by the vacuum action of the expanding cake when the pressure is released. Passageways |61, Fig. 20, extend from the lbottom of the screen |51 to the bottom edge of the slat, whereby nitrate may be drained into the depression |62 in the top ofthe next adjacent slat below. A vertical groove |68 is provided ineach end of each slat |53 near the front side thereof and one or more holes |69 are prohereinafter described and shown in Fig. 1'1, and i any liquid nitrate whichA is forced edgewise through this nlter cloth may enter the groove |68 and pass into the inside of the slat through the holes |68.

When a wire mesh face |51 is used on the face side or the mier slats, as 'shown 1n Figs. 1a m 21,

it permits the liquid nitrate to pass freely through the nlter cloths which are pressed against said wire mesh, but I nnd that the heavy of the wire Vmesh |51.

pressures within the pressure chamber may stretch and eventear the nlter cloth, by pressing it into the spaces between the wires. I overcome this tendency preferably by subjecting the wire mesh to a very high pressure to thereby flatten out said wire mesh before it is installed on the faces of the slats. 'I'he flattening of the wire mesh affords a nattery surface and more bearing area for the nlter cloth and prevents injury of the nlter cloth. This flattening of the wires is shown in Fig. 20.

Fig. 26 shows a fragment of a perforated plate |10, which may be used on the slat |53 in place One advantage of this perforated plate over the wire mesh |51 is that it affords a more even surface and there is less tendency to stretch a nlter cloth which is pressed against the front .of the slat. By omitting or nlling one row of holes near the bottom edge of the plateA |10, as shown at |1|, the same result is obtained as by the use of the nlter |66 in Fig. 19, a consideration particularly important where excessive pressures are employed.

The slat |12 shown inFigs. 22, 23,'and 24 is also of metal construction and has cavities |13 on the inside into which liquid nitrate may pass. A rib |14 extends lengthwise within said slat |12 and is flush with the front edge of the slat. The face of the slat |12 is formed by a metal plate |15 which has slots |16 with rearwardly diverging walls and is secured to the slat |12 by screws |11. The slots |16 and the supporting surfaces between said slots are of suitable shape, size and positioning so that liquid nitrate which is pressed through a nlter cloth, supported by the plate |15, will pass through the slotsj|16 into the interior cavities |13 of the slat andbe discharged from the rear side of the slat through openings |18. Openings I 18', shown'by dotted linesvin Fig. 22, may be -providedin the rib |14 for nitrate to pass through. 'Ihe slat |1-2 has holes |18 formed in enlarged portions of the rib |14 .through which holes |18 bolts or cap screws |80 may extend for the purpose of securing the slats |12 to the link belts. The heads of the cap screws |80 are positioned in openings |8| in the plates |12 and may be nush-with the front side of said plates |12, see Fig. 24. The bottom edge of each slat |12 may have a.l packing strip |82 cemented or otherwise secured thereto, which tends to exclude nitrate from the space between said slats. The top edge of each slat |12 may have a. depression |83 communicably connected with the interior of the slat by notches |84 to catch anynitrate which nnds its way between the slats 4and to direct said nitrate into the cav.- ity within the slat. A horizontal slot '|85 is provided along the bottom of the plate |15 to afford a means for receiving nitrate in a portion of the plate not otherwise provided with slots. The n1- trate entering the slot |85 passes down through openings formed by notches |86 in the inner sideof the plate and will ordinarily nnd its way into the cavities of theAnext adjacent slat through the depression |83 and notches |84. It will'be noted, in Figs. 22 and 24 that the slots |16 ter' minate above the level of the bottom of the interior cavity |13 of the slat |12, and that thel slot |85 is closed at the innerside'by the edge of the slat, thereby leaving a lip or dam at. |81 which corresponds in purpose andl function with the lip or-dam |66 in Figs.,l8 and 20, previously described. Drain holes |88 are provided in the back of each slat |12, preferably just below the t0? Wall and just below the. rib |14 oi saidl s iat, to

facilitate washing out, cleaning and sterilization of the interior cavities of said slats. It will be apparent that these drain holes |88 will be in a suitable position to allow all-liquid to drain out f theslats when the position of the slats is reversed after said slats have passed around the lower sprocket wheels |33 at the beginning of their upward excursion and before they have passed around the upper sprocket wheels |36 at 4the beginning of their downward excursion.

This washing out may be done by directing a sprayof water through the slotted face of the slats as they are moving upwardly on the outer sides of the machine, said slats then being free from the nlter cloth. The end walls of the slats |12 are notched at the front edges, as at |89, Fig.

24, to afford passageways through which liquid nitrate in the edges of a niter cloth which extends around the ends of said slats may now into the slats. In Fig. 24 I also disclose a preferred method of mounting the links MII on .the slats j byncountersinking the base portion of each link into the siat, whereby the ends of the link portion IIB' will abut against solid metal shoulders in the slat and the tendency toshear on the bolts |88 will be greatly lessened. v

'I'he filter beltsll (Fig. 24) contacting the slat faces |15 may be treated or impregnated to render them repellent to nitrate. An example of such a nitrate repellent material, when water constitutes the nitrate, would be a nlter belt made of a fabric in which the threads had been treated or impregnated with paranln. A nitrate repeiflent fabric or belt of this nature will cause the -nltrate which collects in the holes or slots 'of the siat face |15 to form globules 106 when said nitrate is exposed to the vacuum suction action arising from the expanding cake when pressure is released. When nitrate is thus induced to assume the globular form, spaceis left between said globules for air to pass to relieve the vacuum like action without carrying said nitrate back into the niter belt and into the cake. Treating the slat faces with nitrate repellent material, such as aluminum stearate, also renders these faces repellent to the return of nitrate and helps to cause any nitrate in the passageways in said slat faces where experience teaches it naturally forms as a nim, to assume a globular form and y aiiowairtopass inwardly without carrying the ni of rhomboidal form in vertical cross section, the

' top and bottom of said slats'being inclined downwardly and backwardly from the face of the Slat to thereby promote rapid drainage of -nitrate from face to back, both within the siat and between the respective slats in the niter zone. 'I'he said rhomboidai form of the slat has been found,

by experience, to be a most important change in preventing-the re-absorption of the expressed nitrate by the vacuum created 'by the expanding cake when thepressure is released and in .in-`

cursion of the slat outside of the niter zone, the

same rhomboidal form has the important advantage of shedding or discharging the residual nitrate cleaning fluid away from the machine, so that injury to the metallic parts of the machine is prevented. Particularly is this important when the nitrate is of a character detrimental to .the materials of which the machine is constructed. The top walls of the slats |950 and lill' are each recessed as at |89 to provide sufficient space between the closely super-imposed slats to A permit the drainage of the nitrate from the niter .face to the rear of the siat, said space being necessary to prevent the blocking of the drainage by nim production as otherwise results. 'I'he recessed portions |89 may be suitably sloped to deliver the nitrate thus drained to pick-Yup means at any desired location between the two ends vof the slat. The inclined top and bottom walls of slats |90 and |90 cause nitrate to be removed quickly from the proximity of the filter belts, cloths, or nlter faces and tend to prevent-'reabsorption of liquid by expanding solid material at the location where pressure is released. I nnd thatthere is a strong tendency for nitrate to be withdrawn from the siat and re-absorbed by the solid material after said solid material has passed the location of maximum pressure and has started to expand, said expansion exerting a vacuum like.- action. The slats shown in Figs. 25 and 27 minimizes this tendency. by rapidly removing substantially all of the nitrate so that said nitrate has no opportunity to be thus drawn back and reabsorbed by the solid matter. Also in Fig. 25v I provide a relatively thin walled/pervious siat face |10' which cooperates to permit prompt drainage by retaining a thinner nlm of the nitrate in the interstices o f the permeable siat` face. This thin slat face is preferably reinforced by a plurality of webs |14 winch may parailel the top and bottom walls of the slat. The

providing of a plurality of such web members also' provides for an increased drainage surface to the tendencyof the nitrate tov now backwardly,

due to the vacuum produced by the expanding cake when the pressure is released. Drainage ports IBI' may be formed in the rear wail of slat |90' illustrated in Fig. 25 on the plane of each rib member |14'. vThe rib members |14 are preferably provided with relativeiysharp and abrupt frontal edge portions ISI' to act as a dam to retard the return of the nitrate' to the said expanding cake due to the' suction `tendency occurring when the cake expands when the pressure is relieved. Ports |62' may be provided-in the rear wail above ports IGI' to admit air to. relieve any vacuum createdby the expanding 'cake without carrying the filtrate back into the cake and without interfering with the drainage of the nitrate through ports Ill'. v

The siat l" shown in Fig. 27 diners in one respect yfrom the slat shown in Fig. 2 5 in that the front side of said slat is recessed'as at ISI for the reception of a slatiface |52 which is formed of a plate or block of porous niter material. Also inclined rib in Fig. 27 may have passageway IN' adjacent the rear wall to permit nitrate to pas's'downwardly to a discharge out- The two pendent frames lli, Figs. 1 to 5 are connected with each other-by a plurality of noatingiy mounted tie rods' |83, which extend through the holes Ill in the outer ends of the u 'shaped cross'members |21. Relatively strongI soY and heavy compression springs |94 may be provided on the floatingly mounted tie rods |93 at the outer sides of the U shaped cross members |21, and nuts |95 on the ends of said tie rods may serve as adjustable holding means for the springs |94. Suitable washers |99 may be provided at both ends of the springs |94. Due to the fact that the pressure between the pendent frames increases toward the lower end of the machine, I prefer to provide stronger oatingly mounted tie rod members and heavier springs toward the lower end. In Fig. 3, it will be noted that the lowermost springs |94 are made larger and heavier. may be obtained toward the lower end oi' the pendent frames by providing a greater number of springs, which may be done as hereinafter more "fully described, with specific reference to Fig. 45.

By interconnecting the two pendent frames' with the iloatingly mounted tie rods |93 it will be apparent that the pressure of material in the pressure chamber |39 between the two pendent frames will be borne as a tension by said tie rods |93 and will not be transmitted to the stationary frame of the machine. This provides a balanced structure of great strength and minimum weight and affords a very' advantageous construction for high pressure operation.

It will be noted .that rthe uppermost tierrods |93' which connect .fthe two pendent frame members are positioned a short distance above the pivot screws ||1 on which said pendent frame members are swingingly supported and that no springs are provided on these tie rods |93. This is more clearly shown in Figs. 1 to 4 inclusive. The nuts |91 on these -top tie rods are preferably non-rotatably secured to the cross members |21. This may be done by welding said nuts |91 to washers or plates |99 which are welded to the cross members |21. The tie rods |93 each have right hand threads at one end and' left hand threads at the other end, whereby rotation of said tie rods in one direction, withinl Ithe relatively xed and non-rotatable nuts |91 will cause the two pendent frame members to be moved .toward each other and rotation of said .'tie rods in an opposite direction will cause said .two pendent frame members to be moved away from each other, it being apparent that each pendent frame member will be moved the same amount toward or away rfrom the medial vertical plane of 'the pressure chamber |39 in response to rotation of the tie rods |93. To insure equal angular movemen-t of the two tie rods |93' in the same direction, I preferably provide a sprocket Wheel |99 on each of said tie rods and I inter-connect said .two sprocket wheels by an endless link belt 2,00,

see Fig. 2. The tie rods |93' may be .turned by exerting a pull on the link belt 200, it being understood that -these adjustments will' be made when the machine is inoperative and when the pendent frames are not subjected to pressure.

' .and .that a small amount of power will sumce to ifrom being pressed together with the 4possibility 4 of damagingthe same when there is no material in the chamber |38 of the machine. These sleeve members 20| are shownin Fig. 1.

The slat belts which are carried on the two Obviously more spring pressurev pendent frame members |25 serve as supports for woven or fabricated iiltering members. Each tabricated filtering member may be in the nature of an endless illter cloth belt 205 for use in connection with each slat belt, as shown by broken lines in Figs. 1 and 3, or it'may be in the nature of one or more straight strips of filter cloth material not in endless form', orit may be in the na- .ture of a plurality of superimposed illter cloth strips or belts all as hereinafter described and shown in the drawings. The endless lter belts 205, shown in Figs. 1, 3, 4, 5 and 17 are wider than the slat belts and .the edges 205' of said filter belts fold over the ends of the slats |39 as shown in Figs. 4, 5 and 17. These filter belts 205 pass around rollers 200, 201, 200 and 209 at Ithe upper end of the frame and around rollers 2|0 and 2| at the lower end of the frame, see Fig. 3. 'I'hey are pressed against the slat belts by the material within the pressure chamber |39, and movement may be imparted to -them -by the slat belts. In Fig. 3 the filter belts are shown as passingover the guide rollers 206 just before they engage with the slat belts in their downward movement. In

Fig. 44 I have shown a guide member 2|2 posi tioned at the side of the slat belt near lthe upper end thereof and serving Ito fold the edge-of the filter `belt at right angles, whereby the edge of the illter belt may be caused to fold correctly over the ends of thesla-ts |39 as it passes in-to the pressure area of the machine.

Positioned at the sides of -the previously described slat belts and in engagement with the portions 205' of the filter cloths 205, which extend around the ends of .the slats |39, are two side |belts 2|3, preferably impervious and preferably of metallic character to provide low friction. These side belts form walls of the pressure chamber |30 and may be of duplicate construction. Each of the side belts 2|3 is carried on a slat bel-t composed of slats 2|! secured Ito .an endless link belt 2|5. 'I'he link belts 2|5 are mounted on upper sprocket wheels 2 6 and low-er sprocket wheels 2|1, see Fig. 2, and said link belts 2 I 5 have rollers 2|9 provided on the pivot pins 2| 9, which connect the respective links of said` link belts, see

Fig. 17. The rollers 2|9 may run on trackways 220, see Figs. 4, 9 and 17, which may be positioned opposite the. sides of the pressure chamber |39 and extend between the upper and lower sprocket wheels 2|.9 and 2| 1, respectively. The trackways 220 support the link belts 2|5 and slats 2|! and said slats 2li support the impervious side belts 2|3 in close liquid tight contact with the marginal portions 205' of the filter belts 205, which marginal portions 205' are folded over the ends of 'the slats |39 .to provide a iiuid tight Joint between the ends of the slats `arid the side belts. The trackways 220 for .the side belts may be supported by flat springs 22| which extend cross wise of said trackways 220 at frequent intervals, asshown in Figs. 4, 9 and 17. This track 220 is slightly flexible orresilient so that the same may be locally adjusted to make the joint between the side Vb elt vand the filter belts filter tight. The ends of the flat springs 22| have holes 222 for the reception of portions 223 of reduced diameter on the ends of cap' screws 224, Figs. 4 .and 17. The cap screws 224 are .threaded through bosses 225 on the upright side frame members l0, see-Fig. 4, and may be adjusted to vary the pressure of the side belts 2`I 3 against the ends of lthe slats |39 of the main slat bel-ts to make the joints of desired tightness. lThe ilat springs 22| are provided at frequent intervals and are adiustably

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