US2657131A - Discharge device for finely divided fibrous material from a pressure system - Google Patents

Description

H. S. MESSING DISCHANGE DEVICE F0 Oct. 27, 1953 R FINELY DIVIDED FIBROUS MATERIAL FROM A PRESSURE SYSTEM Filed May 26, 1949 4 Sheets-Sheet 2 ATTO N Oct. 27, 1953 H. s. MESS DISCHANGE DEVICE FOR FINE DIVIDED FIBROUS MATERIAL FROM A PRESSURE SYSTEM Filed May 26, 1949 4 Sheets-Sheet 3 .l/ly

J dbm INVENTOR Oct. 27, 1953 H s. MESSING 2,657,131

DISCHANGE DEVICE FOR FINELY DIVIDED FIBROUS MATERIAL FROM A PRESSURE SYSTEM Filed May 26. 1949 4 Sheets-Sheet -4 INVENTOR. Hjflnfir S- Hass I .1

BY Z

' ATT'QRNEY.

Patented Oct. 27, 1953 DISCHARGE DEVICE FOR FINELY DIVIDED FIBROUS MATERIAL FROM A PRESSURE SYSTEM Hjalmar S. Messing, New York, N. Y., assignor to American Defibrator, Inc., New York, N. Y., a corporation of Delaware Application May 26, 1949, Serial No. 95,561

2 Claims. 1

This invention relates to an improved device for continuously discharging solid material, more especially finely divided or comminuted fibrous material suspended or entrained in a fiuid medium in a pressure system, while minimizing the loss of fluid medium and drop in pressure in the system. The present invention is a continuation-in-part of my co-pending application Serial No. 547,686 filed August 2, 1944, now abandoned and is particularly advantageous for discharging fibrous stock from mechanical abrading or defibrating apparatus wherein the defibration of the raw material is carried out in an atmosphere of steam at temperatures considerably above 212 F. and at pressures from approximately 100 to 200 lbs. per square inch. Since such defibrating apparatus is operated continuously it is essential to provide a discharge device for withdrawing fibrous stock which de vice will not deleteriously affect the efiicient operation of the apparatus by requiring the supply of excessive amounts of steam or by allowing a pressure drop within the apparatus.

In one well-known type of defibrating apparatus, the material to be treated, such as wood chips, bagasse, bamboo, sawmill waste and the like, is continuously fed into a mechanical defibrator or abrader in which steam is maintained at a pressure and temperature sufiiciently high to soften the ligneous material of the middle lamella which binds the fibers together. The material being refined is maintained at elevated temperature and pressure while being subjected to the abrading action of relatively rotating refining members. Since the binding effect of the middle lamella of the fibers has been reduced by the high temperature of the steam, a minimum expenditure of power is required to separate the fibers and a minimum of breakage of individual fibers occurs, thereby producing a homogeneous defibrated product.

Heretofore, the refined fibrous stock has been discharged from the defibrator through an outlet duct controlled by a pair of alternately actuated valves arranged in series Within the duct. While this arrangement has operated satisfactorily to discharge fibrous stock from the defibrator without concomitant waste of steam and drop in pressure within the system, the valve controlled outlet mechanism is characterized by a number of distinct disadvantages. For eX- ample, a suitable system of cams, rollers and associated movable valve mechanism are required for rapid opening and closing and a1- ternate actuation of the valves. Moreover, the

rapid operation of the valves results in wear and necessitates frequent inspection, dismantling of the parts and replacement of the valve cones and seats in order to maintain the efficiency of the refining unit. Furthermore the discharge opening could not be changed without removal and replacement of parts.

Accordingly, it is an object of the present in vention to provide a device of the character indicated which may be readily adjusted for variable discharge and which is adapted for continuously delivering fibrous material from a pressure system while substantially maintaining a pressure seal thereon without occasioning excessive wear and replacement of parts.

Another object of the invention is the provision of a discharge device which is constructed and arranged in such a manner as to minimize the possibility of clogging.

An additional object of the invention is the provision of a discharge device having relatively adjustable rotary impingement members serving to dissipate the energy of the fiber jet as it passes through the device and simultaneously operating to break up residual bundles or agglomerations of fibers, thereby resulting in further refining of the fibers as they pass through the discharge device.

A further object of the invention is the provision of a discharge device which may be successfully employed in connection with digesters or cookers in continuous pulp digesting processes.

A particular object of the invention is the provision of an improved discharge device over that disclosed in my co-pending application Serial No. 547,686 filed August 2, 19%, now abandoned, of which latter application, the present application constitutes a continuation-in-part.

The features and advantages of the present invention will be readily apparent in the course of the following detailed description taken in connection with the accompanying drawing which illustrates a preferred embodiment of the invention, and wherein:

Fig. 1 is a plan view, partially in cross-section showing the improved discharge apparatus associated with a defibrating machine;

Fig. 2 is a cross-sectional view on an enlarged scale showing a preferred embodiment of the discharge apparatus itself;

Fig. 3 is a view similar to Fig. 2, but showing another embodiment of my invention;

Fig. 4 is a cross-sectional view taken on line 44 of Fig. 3;

Fig. 5 is a cross-sectional view taken on line 5-5 of Fig. 3;

Fig. 6 is an elevational view, partly in section on line B6 of Fig. 7, of a third embodiment of a discharge device;

Fig. 7 is an end elevation of the device of Fig. 6 with the control wheel removed;

Fig. 8 is an elevational view on an enlarged scale of the adjustable rotor element of the device showing the knurled segments of the conical impingement members; and

Fig. 9 is an enlarged fragmentary detail illustrating the cooperation between one of the ro tary impingement members and its respective surrounding housing portion to define an adjust able path of flow through the device.

Referring to the drawings, reference character I6 designates generally a feeding device. This includes a hopper E2 to which is supplied lignocellulose material, preferably in the form of wood chips. A twin-screw conveyor l4 located at the bottom of the hopper carries the chips into a cylinder It within which is located a piston which is reciprocated by means of a piston rod 28 connected to a cross-head 26. A connecting rod 22 is connected between the cross-head 2t and a crank 24, the latter being rotated through suitable gearing 26 by means of an electric motor 28.

The interior of the left-hand portion of cylinder i6 is formed as a plurality of frustro-conical sections 39 and opens into the upper part of a receiver 32. A conduit 3 connects the lower part of the receiver with the center of the housing 36 of a rotary disc refiner. A screw conveyor 38 driven by an electric motor ii! is disposed within the conduit 34.

A stationary disc 42 is located within the housing 36 and is formed with a central opening in alignment with the conduit 34. A rotary disc 44 is mounted on a shaft 45 which is rotated by a motor 43 through a multiple belt drive 56. The clearance between the discs 42 and M may be adjusted by means of a handwheel 52. The housing 36 is provided with a tangential outlet opening 54. Steam under suitable pressure is admitted to the receiver 32 through the conduit 56 and to the refiner through the conduit 58.

The apparatus so far described is a standard commercial product and is substantially shown in Asplund Patents No. 2,008,892 and No. 2,145,- 851.

Connected to the outlet 54 of the refiner is a conduit 68 which leads to the cylindrical casing 62 of the improved discharge device. As shown in Fig. 2, a nozzle GA may be located between the outlet 54 and the conduit 6!], although it is to be understood that the nozzle may be omitted.

A conduit 58 communicates with the cylinder 62 and leads to a cyclone T0 or other suitable receptacle. Located in the cylinder 62 between the conduits B l and 68 is one or more transverse disc-shaped partitions 12 provided with central openings M. Between the partitions and between the forward partition and the inlet end of the cylinder 62 are liners it. Both the partitions and the liners are preferably made from a very hard and wear-resisting material having an abrasive surface, such as Carborundum.

A shaft 18 is rotatably mounted in combined radial and thrust bearings 80 and 82 carried in pedestals 84 and 85, respectively, and in a slide bearing 88 supported in the rear end wall 90 of the cylinder 62. A stuffing box 82 is provided where the shaft extends through the wall 90. Affixed to the forward end of this shaft is one or more Carborundum discs 94, the number of discs being equal to the number of partitions 12. At the outlet side of the rearmost disc the shaft :3 preferably carries a baflle disc 95, which may be of Carborundum or steel.

The bearings and 82 are shiftable axially in their pedestals 84 and 86 by means of a handwheel 98 so as to vary the axial clearance between the rotary discs 94 and the stationary partitions 12. A pulley Hill is mounted on the shaft 18 and is driven through a multiple belt drive its by an electric motor I84. A water pipe 166 may communicate with the left-hand end of the cylinder 52 as by being connected to a suitable aperture in the end wall 99.

The above described device operates as follows:

Suitable ligno-cellulose material such as wood in the form of chips is introduced into the hopper [2, the chips being conveyed by the twinscrew conveyor l4 into the cylinder l6 and as the piston reciprocates therein it compresses the chips so as to form a suitable solid plug in the left-hand end of the cylinder. This plug is able to hold the steam pressure within the apparatus and thus prevent the escape of any substantial amount of steam at the feed end, The conical sections 30 prevent the plug from being blown back by the steam pressure as the piston reciprocates to the right. When the piston again moves to the left additional chips have been fed into the cylinder and these are compacted between the piston and the plug, with the result that the plug is advanced to the left into the receiver 32. As soon as the end of the plug is relieved of its confinement as it enters the relatively large receiver, it breaks up and the individual chips fall to the bottom of the receiver. From here they are moved by the screw conveyor 38 to within refiner housing 35. Steam is admitted through the conduits 56 and 58 at a pressure such that the temperature is at or above that at which the middle lamella which bind the fibers of the wood together is markedly softened.

The chips in this heated condition are introduced between the discs 42 and 44 and due to rotation of the latter the fibers are separated from each other. A minimum amount of power is required for this operation due to the fact that the middle lamella has lost its adhesive property due to the temperature. Moreover, the fibers may be separated by the discs with a minimum of damage to the individual fibers.

From the housing 35 the fibers in separated state pass through the outlet 54 to within the conduit 60. If the nozzle 64 is provided this introduces a certain resistance to flow, thus reducing the rate at which steam escapes from the housing into the conduit $5,

From the conduit 69 the stock is introduced into the cylinder 62 and strikes the first rotating disc 94. This disc imparts a rotary movement to the stock and consequently centrifugal force aids in causing it to flow outward against the liner 16. Here its direction of flow is abruptly changed and the stock is caused to flow around the outer edge of disc 94 and thence must pass radially inwardly to the central openings 'M in the stationary partition 12. Centrifugal force tends to retard flow in this direction. From here the stock strikes the next rotating disc 94 and must pass outwardly around its periphery and thence inwardly to the central opening 14 in the next stationary partition.

Due to the fact that the partitions, liners and discs are made of an abrasive material, such as Carborundum, they have a further refining action on the stock and consequently tend to separate any bundles of fibers which may have passed through the defibrating machine.

Stock passing through the central opening I4 in the left-hand partition strikes the baffle 96 which is provided chiefly for preventing the stock from impinging directly around the bearing 88. From the left-hand end of the cylinder 62 the stock passes through the conduit 68 to the cyclone 10. If desired, water may be introduced through the conduit I02; to aid in slushing the stock out of the cylinder 62 and into the cyclone and it also serves to condense steam.

The velocity of stock and steam which passes through the discharging device may be controlled by varying the speed of rotation of the discs 94 and the clearance between these discs and the partitions 12 so as to pass just the amount discharged from the defibrator, and consequently the escape of excess steam may be prevented. The greater the speed of the discs, the greater will be the centrifugal force tending to retard passage of the stock from the outer regions of the cylinder to the central openings 14 in the stationary partitions. Likewise, reducing the clearance between the discs and the partitions will also reduce the flow. Also, the provision of additional discs and partitions would have the same effect.

In the embodiment illustrated in Figs. 3, 4 and 5 a nozzle III} is located within the conduit 50 which is connected to the outlet 54 of the defibrator. An annular space H2 is provided between the nozzle and the conduit 60, into which water may be introduced tangentially through the conduits H4 and H6, as is shown more particularly in Fig. l. An annular injector nozzle I18 is provided between the inner end of the nozzle I I8 and a partition I28.

Mounted within the casing 62 on the shaft 18 of this embodiment are three rotary discs 96a, which are similar to the discs 96 of Fig. 2, but as shown are provided with convex peripheries. Ahead of the first disc 96a is a stationary liner I22 formed with a funnel-shaped aperture I24. Behind this disc is a stationary partition I26 which is similar to the partition 12 in Fig. 2, except that the central aperture therein is formed with a convex surface.

Next to the partition I26 is a disc-shaped member IZS having a central aperture with which communicates a tangential passage I30, as is shown more particularly in Fig. 5. This passage is connected to a conduit I32 through which water may be supplied. On the other side of the disc I28 is a partition I34, which is located ahead of the next rotary disc 96a. A similar partition I36 is located between the second and third rotary discs, while another similar partition I32 is located behind the last disc.

Between the various partitions and in radial alignment with the rotary discs are annular liners I ill, the openings through which are provided with concave surfaces. The partitions, rotary discs and liners are preferably made of abrasive material, such as carborundum.

The shaft 78 may be moved axially in a manner similar to that shown in Fig. 2 in order to vary the clearance between the rotary and stationary members, and may be driven in a similar manner.

This embodiment operate as follows:

The stock discharged from the defibrator through the outlet 54 enters the nozzle I I9 which, due to its decreasing diameter, introduces a certain resistance to flow and increases the velocity of the stock. Water supplied through the conduits II4 and H6 is caused to flow through the nozzle H8 by injector action and consequently the pressure of the water supplied through these conduits need not be as high as the steam pressure in the defibrator. The water introduced through the nozzle III; is mixed with the stock and aids in the further refining of the latter as it passes through the discharge device.

The mixture of water and fibers passes around the rotary discs and through the apertures in the stationary partitions in the manner as described in connection with the first embodiment. The abrasive nature of the discs, partitions and liners serves to further refine the stock, and the pressure is reduced in the same manner as above described.

Suihcient water may be introduced through the conduit I32 between two of the rotary discs 96a to form a suspension of the fibers, which aids further in the refining thereof as they pass the subsequent rotating discs. The mixture of fibers and water may be discharged into a cyclone or other suitable receptacle in the same manner as above described.

Actual tests have proved that the above described device due to the relatively narrow and tortuous passages, restricts the rate of flow sufficiently so that the quantity of steam escaping is maintained within reasonable and economic limits, while clogging of the passages by the stock is prevented due to the rotation of the discs. In addition, the abrasive action is such as to separate into individual fibers substantially all of any remaining fiber bundles.

Referring now to Figs. 6 to 9 of the drawings, the discharge device includes an inlet conduit 2I0 which leads to the casing ZII of the device. As shown in Fig. 6, a nozzle 2I2 may be disposed in the inlet conduit 2H! adjacent the casing 2| I. A shaft 2I3 is rotatably mounted in combined roller and thrust bearings 2 I4 carried on supports 2I5. A combined slide bearing and stuifing box 2 I6 is provided in the rear end wall 2| Ia of easing 2! I where the shaft 2 I 3 extends through said rear wall.

Afiixed to the forward end of shaft 2I3 within casing 2II is one or more rotary impingement members ZI'I and 2l8 which are preferably formed with rearwardly divergent or conical impingement surfaces in order toutilize the centrifugal force exerted upon the fiber jet passing through the discharge device in such a manner as to offer minimum resistance to the flow of the fibrous stock and to prevent clogging of the device. The foremost rotary member ZI'I may be threaded upon the front end of the shaft 2I3 as shown at 2I9 and may be secured in place by inserting a suitable tool in a hole 220 extending transversely through said member adjacent the forward end thereof. Rotary member 2 I8 is preferably frusto-conical in shape and may be secured on shaft 2I3 in any suitable manner.

Rotary members 2H and 2I8 cooperate with internal liners ZIIa and H811 to provide for variable discharge through the device by axial displacement of shaft 2I3, as will be more fully described hereinbelow. The angular inclination of the surface of the liners 211a and 218a is preferably slightly less than that of the impingement surfaces of rotary members 2H? and 2m respectively in order to effect positive closure of the passage through casing 2 when required. As best shown in Figs. 8 and 9 the impingement surfaces of rotary members 2 If and 2m are provided with a plurality of spaced grooves 225 defining therebetween knurled segments 226 and 221 respectively. The presence of grooves 225 serves to increase the centrifugal force exerted on the fiber jet as it is whirled against the rotary impingement members 2|? and 2 i8. Simultaneously the knurled segments 226 and 22? serve to break up and further refine any residual fiber bundles, clusters or agglomerations in th fibrous stock passing through the device. The angularly inclined surfaces of casin liners 2lla and HM may also be knurled, if desired. The material leaves casing 2 by means of a discharge conduit 228 which may be connected to any suitable receiver (not shown). The liners Mia and 218a and the rotary impingement members Zil and H8 may be made from suitable abrasive material, such as Carborundum, as an alternative to being knurled, in order to achieve the desired refining action.

In order to vary the discharge rate through the device means are provided for varying the axial clearance between th rotary impingement members 2|! and H8 and the casing liners HM and H80. by axial displacement of the shaft 2 l3. Bearing supports 2 l are mounted on a carriage or base plate 230 which is slidably received between bearing members 23l fixed to a frame or channel members 232. An upright plate 233 is fixed to channel member 232 and carries the threaded shaft 234 of a handwheel 235, the inner end of said shaft being secured to the outer bearing support 2H3. The rate of discharge through the device may thus be varied by adjusting the handwheel 235 to vary the clearance between the rotary impingement members 2i? and 2m and the casing liners Zll'a and Zita. Ihe forward displacement of shaft 2i3 may be limited by means of an adjustable stop-bolt 236, as shown in Fig. 6.

In order to prevent damage to the rotary impingement members and the casing liners if some foreign material such as a nail should become lodged between said members and liners provision is made for automatic retraction of shaft 213. Handwheel shaft 2% carries a fixed collar 23? and a compression spring 238 is interposed between outer bearing support 215 and said collar. Excessive pressure on shaft 2 l3 beyond the limit of tension of spring 238 will result in temporary retraction of said shaft and the rotary member 2 I1 and 218 until the foreign object is blown out of the casing through outlet conduit 228.

A pulley 242) is mounted on shaft 2i3 which may be driven from a suitable power source through a multiple belt drive 2 5i. A water pipe 242 may communicate with the inlet end of the casing 2H by means of a jacket 243 and inlet openings 244 to aid in flushing the material through the discharge device.

The arrangement shown in Figures 6 to 9 presents significant advantages over the disclosure in Figures 1 to 5 wherein variable passage of material through the discharge device is provided by a series of relatively adjustable discs and liners. In the aforementioned application the control of clearance between the discs and liners is not positive and the now of material through the central aperture of each liner is resisted by sistance to flow occurs and the rate at which steam enters casing 211 is reduced. Also the presence of nozzle 2l2 concentrates the stream of fibrous stock into a jet which impinges against the pointed end of rotary member 2H. Rotary member 2!? imparts a rotary movement to the fibrous stock and generates centrifugal force aided by the grooves 225. Because of the rear- Wardly divergent impingement surfaces of the rotary members 2!! and 2|8 and their cooperation with the liners 2|?a and Zita which are complementary in contour to said impingement surfaces, the discharge device advantageously utilizes the centrifugal force generated therewithin to promote the flow of fibrous stock there through and prevent clogging. Simultaneously the knurled segments 226 and 221 serve to break up and further refine residual fiber bundles and clusters.

Since certain modifications may be made in the discharge device of the present invention without departing from the scope thereof, it is intended that all matter contained in the foregoing description and shown in the accompanying drawing be interpreted merely as illustrative and not in a limitin sense.

Vfhat is claimed is:

l. A device for continuously discharging finely divided fibrous material from a pressure system while substantially maintaining a pressure seal thereon, comprising a casing having a restricted inlet opening provided with a flaring portion extending away from the opening, a shaft rotative within the casing, said shaft being longitudinally adjustable and carrying a plurality of spaced conical members, one of said conical members being a cone having an apex located in said flared portion and spaced from the wall thereof, the second conical member being frustro-conical, each of the conical members having at least a portion of its surface roughened and grooved, the apex portion of the cone that is located in the flared part of the inlet opening being relatively smooth and free of the roughness and grooves, the interior of the casing being provided with a plurality of spaced liners maintained in end-toend abutment, one of each of said liners extending about and being spaced from the periphery of each conical member, one of the liners being formed with a recess in one end of greater diameter than the conical members, which recess is situated at a location to form a chamber located intermediately of the conical members.

2. A device for continuously discharging finely divided fibrous material from a pressure system while substantiall maintaining a pressure seal thereon comprising a casing having an inlet passage having converging walls leading to a restricted opening, the passage flaring beyond the opening, a shaft rotative within the casing, said shaft being longitudinally adjustable and carrying a cone at one end, said cone having a pointed 9 apex defining the end of the shaft, said apex being located in and surrounded by and spaced from the flared portion of the wall of the inlet passage, a frustro-conical member fitted on the shaft and spaced from the cone, the cone and frustro-conical member each having at least a portion of its surface roughened and grooved, the apex portion of the cone that is located in the flared part of the inlet passage being relatively smooth and free of the roughness and grooves, the interior of the casing being provided with a plurality of spaced liners maintained in end to end abutment, one of each of said liners extending about and being spaced from, the cone and frustro-conical member respectively, one of the liners being formed with a recess in one end of greater diameter than the cone and frustroconical member, which recess is situated at a location to form a chamber located intermediately of the cone and conical member.

HJALMAR S. MESSING.

References Cited in the rim of this patent UNITED STATES PATENTS Number Number Name Date Herron May 19, 1874 Gould Jan. 20, 1885 Clafiin May 2, 1893 Manson Mar. 11, 1924 Barnot et al. Sept. 15, 1925 Hussey Mar. 10, 1931 Fraser Sept. 26, 1933 Wollenberg Nov. 2'7, 1934 Asplund July 23, 1935 Asplund Feb. 7, 1939 Inglis Feb. 5, 1946 FOREIGN PATENTS Country Date Great Britain of 1909 Sweden Dec. 19, 1944

Claims (1)

1. A DEVICE FOR CONTINUOUSLY DISCHARGING FINELY DIVIDED FIBROUS MATERIAL FROM A PRESSURE SYSTEM WHILE SUBSTANTIALLY MAINTAINING A PRESSURE SEAL THEREON, COMPRISING A CASING HAVING A RESTRICTED INLET OPENING PROVIDED WITH A FLARING PORTION EXTENDING AWAY FROM THE OPENING, A SHAFT ROTATIVE WITHIN THE CASING, SAID SHAFT BEING LONGITUDINALLY ADJUSTABLE AND CARRYING A PLURALITY OF SPACED CONICAL MEMBERS, ONE OF SAID CONICAL MEMBERS BEING A CONE HAVING AN APEX LOCATED IN SAID FLARED PORTION AND SPACED FROM THE WALL THEREOF, THE SECOND CONICAL MEMBER BEING FRUSTRO-CONICAL, EACH OF THE CONICAL MEMBERS HAVING AT LEAST A PORTION OF ITS SURFACE ROUGHENED AND GROOVED, THE APEX PORTION OF THE CONE THAT IS LOCATED IN THE FLARED PART OF THE INLET OPENING BEING RELATIVELY SMOOTH AND FREE OF THE ROUGHNESS AND GROOVES, THE INTERIOR OF THE CASING BEING PROVIDED WITH A PLURALITY OF SPACED LINERS MAINTAINED IN END-TOEND ABUTMENT, ONE OF EACH OF SAID LINEAR EXTENDING ABOUT AND BEING SPACED FROM THE PERIPHERY OF EACH CONICAL MEMBER, ONE OF THE LINERS BEING FORMED WITH A RECESS IN ONE END OF GREATER DIAMETER THAN THE CONICAL MEMBERS, WHICH RECESS IS SITUATED AT A LOCATION TO FROM A CHAMBER LOCATED INTERMEDIATELY OF THE CONICAL MEMBERS.

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