US3411986A - Axial flow rotary feeder for cellulose digester - Google Patents

Description

NOV- 19, 1958 R. L''BUcHBr-:RGER ETAL 3,411,986

AXIAL FLOW ROTARY FEEDER FOR CELLULOSE DGESTEH Filed Aug. 4, 1965 5 Sheets-Sheet l [uw 2%/ ATTORNEYS l M l I 291/ Nov. 19, 1968 R. l.. BUCHBERGER ETAL 3,411,986

AXIAL FLOW ROTARY FEEDER FOR CELLULOSE DIGESTER Filed Aug. i., 1965 3 Sheets-Sheet 2 46 mw ATTORNEYS Nov. 19, 1968 R. L. BUCHBERGER ETAL AXAL FLOW ROTARY FEEDER FOR CELLULOSE DIGESTER Filed Aug. 4, 1965 5 Sheets-Sheet 5 Q M ATTORNEYS United States Patent 3,411,986 AXIAL FLOW ROTARY FEEDER FOR CELLULOSE DIGESTER Ronald L. Buchberger and Arnold J. Roerig, Beloit, Wis.,

assignors to Beloit Corporation, Beloit, Wis., a corporation of Wisconsin Filed Aug. 4, 1965, Ser. No. 477,242 4 Claims. (Cl. 162-246) ABSTRACT OF THE DISCLOSURE Apparatus for feeding cellulosic material to a continuous pulping digester. The apparatus is a rotary feeder valve having -a frusto-conically shaped bore with at least two pairs of inlets and outlets therein and a complementarily shaped rotor in the bore with passages in the rotor. The passages are arranged to interconnect rst one of the said pairs of inlets and outlets -an'd then the other pair upon rotation of the rotor and screens are placed in either the rotor or the outlets in the bore for collecting chips in the passages.

This invention relates generally to pulp and paper-making apparatus `and more particularly to apparatus for transferring and feeding wood chips during a continuous pulping process.

Advances have been made in the development of continuous pulping processes `and there are now a number of soundly developed systems for continuous pulping, particularly of the chemical and semi-chemical types. Continuous pulping can afford many advantages over a batch operation, among which are reduced time requirements, a more uniform product, utilization of better control methods, greater exibility and the ability to use lower liquor ratios.

Continuous pulping processes are often complicated, however, and have presented problems of mechanical design. For example, in some operations such as in feeding wood chips to the digesters or in transferring the wood ychips from one digester to another the chips may desirably be first carried in one fluid medium such as a first liquor and then transferred to another liuid medium such as a second liquor which might be at a different pressure, temperature, etc., than the lirst liquor.

The present invention is addressed to such problems and provides means not only for effecting such transfer but for accomplishing the transfer continuously las required in feeding wood chips in a continuous pulping process.

The feeding or transfer apparatus of the present invention is simple in design, relatively inexpensive in manufacture, provides a high transfer or feeding capacity, is easy to operate, can be controlled automatically, is rugged in construction and can serve a long, useful life.

It is, therefore, an object of the present invention to provide means for transferring wood chips from a first liquor to a second liquor, the two liquors having different conditions of pressure or temperature or the like.

Another object of the invention is to provide a digesting system for a continuous pulping process including means for continuously delivering wood chips to the digester for processing.

Another object `of the invention is to provide `a rotary feeder for a digester system incorporating a stationary stator and :a rotatable rotor and including means for reducing wear between the stator and the rotor.

A further object of the invention is to provide, in a vertical feeder having la rotor rotatable within the bore of a stationary stator, a pressurized chamber within the bore to counterbalance the weight of the stator to reduce wear.

3,41 1,986 Patented Nov. 19, 1968 "ice Yet another object of the invention is to provide a feeder for 'a digester system in a continuous pulping process whereby wood chips are continuously transferred from `a first liquor to `a second liquor for delivery to a digester, and in which only one moving part is required in the feeder.

Still another object of the invention is to provide a feeder or transfer mechanism which is simple in design, relatively inexpensive in manufacture, provides a high transfer capacity, is easy to operate, is rugged in construction, `and can serve a long, useful life.

Many other features, advantages and additional objects of the present invention will become manifest t0 those versed in the :art upon making reference to the detailed description which follows and the accompanying sheets lof drawings, in which preferred structural embodiments incorporating the principles of the present invention are shown by way of illustrative example only.

In the drawings FIGURE 1 is a schematic plumbing diagram of a continuous digesting system incorporating the principles of the present invention;

FIGURE 2 is a side elevational view of a transfer or feeder unit constructed in accordance with the principles of the present invention;

FIGURE 3 is a top plan view of the feeder unit of FIGURE 2;

FIGURE 4 is a sectional side view of the feeder unit taken along lines IV-IV of FIGURE 3;

FIGURE 5 is a horizontal sectional view of the feeder unit taken along lines V-V of FIGURE 4; and

FIGURE 6 is a fragmentary vertical sectional view of the feeder illustrating another embodiment of .a screening rmeans thereof.

As shown in the drawings Although the principles of the present invention are applicable in any system wherein solids are to be transferred from one fluid medium to another; a particularly useful application is made to a pulping process in the Imanufacture of stock for making paper products wherein wood chips are treated mechanically and/or chemically at a plurality of treatment stations or zones and may be transferred from one treatment zone to another in one or more liquor mediums, as will be understood by those skilled in the art.

The present invention is also particularly useful where the transfer of the solids is essentially a continuous process. For example, generally in a pulping process the wood chips are subjected to ycertain treatment before entering the digesters. In a batch operation, the chips are moved periodically lfrom one treatment station or zone to another, and then delivered to the digester or digesters in a slug or batch. As noted hereinabove, a batch operation is not generally as desirable as a continuous process wherein the chips are continuously moved through the various treatment zones and into and through the digesters.

A continuous pulping lprocess, however, raises certain problems, not the least of which involves the continuous transfer of the chips from one fluid medium to another through the various treatment zones and into the digesters.

The present invention provides improved means for effecting such transfer and for continuously moving the chips through the various treatment zones and into the digesters. Y

Referring to FIGURE 1, a typical digester is indicated generally at reference numeral 10. Usually the digester receives the chips after they have been worked on in other treatment zones.

For example, in some pulping processes the chips are delivered from a chipper or a grinder ina first liquor medium to a first treatment zone. The particular liquor utilized is generally necessary for the proper treatment of the chips and after this phase of the process is completed the chips may be moved to a second treatment zone. The second treatment may require a second liquor, which may be chemically dilferent from the first liquor or may differ only in temperature or pressure. In any event, it may not be the same liquor or lmay not be maintained under the same conditions as the first liquor, and therefore the chips are transferred from the first to the second liquor. In so doing the two treatment zones should re- -main isolated from one another so that a higher pressure or temperature of the liquor of one will not be reduced to that of the other.

In FIGURE 1 it will be assumed that the treatment involved in the digester requires a high pressure liquor and that the next preceding treatment station utilizes a liquor similar to the liquor used in the digester process, but maintained at a lower pressure. It will be understood, however, that the difference between the two liquors could be temperature rather than pressure, or temperature and Ipressure, or the two liquors could differ chemically. However, for one or more of these reasons it is assumed that it is desirable to keep the two liquors separated, or at least substantially so.

Reference numeral 11 denotes a conduit for conveying a flow of low pressure liquor having wood chips suspended therein from a treatment zone which next precedes the digester 10 in a pulping process. Assume that the digester 10 utilizes a high pressure liquor which is conveyed by a conduit 12 and which ows in the direction indicated from a source thereof. The wood chips being carried in the low pressure liquor in conduit 11 are to be transferred to the high pressure liquor iiowing in conduit 12, and `for that purpose the respective conduits are connected to a feeder or transfer unit indicated generally at 13 which is constructed in accordance with the principles Iof the present invention.

Reference numeral 14 denotes a conduit carrying the Vlow pressure liquor after it has passed through the feeder unit 13 and after the wood chips have been removed therefrom and transferred to the high pressure liquor. Reference numeral 16 denotes a conduit carrying the high pressure liquor after it has passed through the feeder 13 and after the chips have been transferred thereto, and this conduit is connected to the digester 10 for feeding the digester with a supply of treated chips.

Referring to FIGURES 2 and 3, the feeder unit 13 is more particularly characterized as comprising a generally cylindrically shaped vertically upstanding stator portion 17, a drive portion 18 at the lower end of the stator and having suitable drive means such as an electric motor 19, connected thereto, and a top portion 20 situated at the upper end of the stator and having mounted thereon a bearing assembly indicated generally at reference numetal 21.

A plurality of conduit connectors extend from the stator 17 and are adapted for connection to the various conduits which receive and deliver theliquor and wood chips transferred to and from the feeder 13.

For example, in the illustrated embodiment of the feeder 13 four connectors indicated respectively at reference numerals 22a-22d are connected in fixed assembly by suitable means such as a weldl connection or the like to the upper portion of the body or stator 17 and are spaced circumferentially 90 around the periphery of the stator. At the lower end of the stator another group of four connectors indicated at 23a-23d are also mounted on the stator in vertical alignment with connectors 22a-22d. Each 0f the connectors includes a ange 24 for connection to the various conduits 11, 12, 14 and 16 although it will be understood that where two or more of the connectors are connected to a single conduit suitable means such as a header `may be utilized in making the connection.

Referring to FIGURES 4 and 5 it will be noted that all of the connectors are in open communication with the interior of the body or stator portion 17 through a plurality of complementarily aligned openings as indicated at 25 formed in a longitudinal wall 26 of the stator 17.

Rotatably carried within the stator 17 is a generally cylindrically shaped rotor 27 having formed therein a plurality of axially extending passages which in the embodiment illustrated are constructed as recesses formed in a peripheral wall 28 of the rotor 27. The passages are eight in number indicated respectively at reference characters 29g-2911 and are spaced circumferentially equi- -distantly around the periphery of the rotor. Each of the passages is separated from adjacent passages by means of a pair of diverging walls 30 and 31 which extend-radially outwardly from a center or hub portion 32 of the rotor.

Also housed within the stator 17 is a tubular liner 33 Iwhich is shaped complementarily to an inner surface 34 of the stator wall 26 and the peripheral surface 28 of the rotor 27. The liner 33 also has formed therein a plurality of complementarily aligned openings as at 36 to afford open communication of the connectors with the interior of the stator 17.

A pair of coaxial shafts 37 and 38 extend from opposite end walls 39 and 40 of the rotor 27, shaft 37 extending upwardly into the top portion 20 of the feeder and shaft 38 extending vertically ldownwardly into the drive portion 18. Suitable packing members 41 and 42 are provided on the respective shafts 37 and 38 for pre'- venting excessive leakage therepast. A pair of radial thrust bearings 43 and 44 are mounted respectively in the top portion 20 and the drive portion 18 for journalling shafts 37 and 38 and in order to rotate the rotor 27 a lower end 46 of the shaft 28 is splined for driving connection with a gear 47 which is in meshing engagement with a Aworm gear co-rotatably connected to a drive shaft 48 driven by the motor 19 (FIGURE 2).

In order to explain the operation of the feeder 13 assume that connectors 221, and 22d are connected by suitable header means to con-duit 11 which is, in turn, connected to the source of a first liquor and chips, and connectors 23h and 23d, which are spaced axially from connectors 22h and 22d, are connected =by suitable header means to conduit 14 for carrying away the first or low pressure liquor from the feeder after the chips Ihave' been removed therefrom. Connectors 22a and 22e are connected by conduit 12 to the second or high pressure liquor to which the chips are to be transferred and connectors 23,l and 23c are connected to the conduit 16 for delivering the second liquor and chips to the digester 10. It will be appreciated, however, that connectors 22a and 22c could be connected to conduit 16 and connectors 23a and 23c to conduit 12 for reverse -ow of the second liquor through the feeder 13.

As the rotor 27 is turned by the drive mechanism each of the passages 29-291l will sequentially interconnect in fluid communication first connectors 22d and 23d (likewise 22h and 23h) and then connectors 22a and 23a (likewise 22c and 23C). y

For example, in FIGURE 4 the passage 29g is situated so as to communicate connector 22d with connector 23d. The first liquor and chips thereby flow from connector 22d into the passage 29g, wherein the chips are retained bymeans of a screen 49 formed in the liner 33 across the opening of the connector 23d. Y

Upon continued rotation of the rotor 27 (approximately for the embodiment illustrated) the passage 29g with the chips collected therein will communicate connectors 22,a and 23a, whereupon the chips will be hushed from the passage to be delivered with the second liquor to the digester.

It will lbe appreciated that as a resultof the arrangement of the passages 29g-29h, a quantity of chips are continuously collected in two of the passages and are continuously flushed from two different passages, as a result of which the transfer of the chips from the first to the second liquor and the delivery of the second liquor and chips to the digester is a substantially continuous operation.

lt may be desirable for the screen means to be for-med directly on the rotor 27 rather than in the liner 49 (which is effectively the body wall 26). Referring to FIGURE 6, in an alternative arrangement a screen member 49a shaped complementarily to the curvature of the liner 26 is mounted at the lower end of a typical passage 29 for collecting the chips in the passage. It will be appreciated that in this arrangement a screen member 49a is required for each of the passages 29,72%, and furthermore it will be appreciated that the second liquor must be backflushed through the rotor to ush the chips therefrom. In FIGURE 4, for example, if a plurality of screen members 49a were -mounted respectively at the lower end of each of the passages 29g-29h, the conduit 12 (FIGURE 1) would be connected to the connector 23 rather than 22 and conduit 16 would be connected to connector 22a, whereby the second liquor would back ush the chips olf of the screen members 49.,1 and out of the passages as the respective passages interconnected connectors 23a and ln or-der to provide a good sealing or substantially leakproof relation between the engaging faces of the rotor 27 and the liner 33, in the illustrated embodiment the wall 26 of the stator 17, the liner 33 and the peripheral wall 28 of the rotor 27 are frusto-conically shaped and taper inwardly at the lower end thereof. A gap or space 50 is provided between the top end wall 39 of the rotor 27 and a radial face or end plate 51 of the top portion 20. A relatively larger space or chamber 52 is provided between the lower end wall of the rotor 27 and a radial end plate 53 of the drive portion 18. As a consequence thereof the rotor 27 is movable axially within the stator 17 Iwithin the limits defined by the end plates 51 and 53.

ln or-der to counterbalance the weight of the rotor 27 and the axial forces acting on the rotor as a result of the flow of liquor therethrough, and also to reduce wear between the engaging faces of the rotor 27 and the liner 33, a conduit 54 is connected at one end 56 thereof to the lower chamber 52, and at the other end thereof to a suitable source of pressurized uid. A pressure regulator valve 57 is mounted in conduit 54 in order to regulate the pressure of chamber 52 and to thereby control the counterbalancing effect on the rotor 27.

Any pressurized uid may be utilized for this purpose. If steam is available an additional conduit 58 may also be connected to chamber 52 for removing condensate from the chamber and a steam trap or condensate Valve 59 may preferably be mounted in the conduit 58 as will be understood by those skilled in the art.

In order to accommodate axial thrust of the rotor 27 as a result of the pressurization of chamber 52, an axial thrust bearing 60 is mounted at the upper end of shaft 37 and is restricted in upward movement thereof by a collar 61 and the axial thrust bearing 60, a handle 66 is mounted may be adjusted vertically by means of a threaded stud 62 connected to the collar 61 and received in a complementarily threaded bore 63 formed in a cover 64 of the bearing assembly 21. In order to facilitate rotation of the stud 62 and consequently vertical adjustment of the collar 61 and the axial thrust bearing 60, a handle 66 is mounted at the upper end of the stud 62.

As a result ofthe axial adjustability of the thrust bearing 60, the lower chamber 52 may be pressurized to a relatively high pressure but the rotor 27 will be limited in axial movement to provide for minimum wear between the engaging faces of the rotor 27 and the liner 33 while also maintaining a substantially leak-proof relationship therebetween.

With respect to radial thrust forces acting on the rotor 27 it will be noted that as a result of the diametrically opposite arrangement of the connectors 22h and 22d, both of which yare connected to the first liquor, the diametrically opposite arrangement of the connectors 22,L and 22C, which are spaced circumferentially with respect to connectors 22h and 22d and both of which are connected to the second liquor, and the diametrically opposite arrangement of the corresponding connectors 23a-233, the radial thrust forces acting on the rotor 27 are completely balanced, regardless of the angular disposition of the rotor during rotation thereof.

Although in the embodiment illustrated the lower connectors 23a-23d are in vertical alignment with the connectors 22a-22d, it will be appreciated that the upper and lower connectors may be lsomewhat circumferentially offset with respect to one another while maintaining a 90 circumferential spacing between the connectors 22B-22d and `between connectors 23a-23d to maintain a balanced radial thrust condition on the rotor 27.Such arrangement, of course, would necessitate a corresponding helical construction of the passages 29-291l in the event that the degree of offset between the axially spaced upper and lower connectors required such modification.

Although these and other minor modifications might be suggested by those versed in the art, it should be understood that we wish to embody within the scope of the patent warranted hereon all such modifications as reasonably come Within the scope of our contribution to the art.

We claim as our invention:

1. In a digester system for digesting wood chips,

a rotary feeder for liquor and chips comprising a stator having means forming a vertically extending frusto-conically shaped bore therein, means forming at least two pairs of openings in said stator each of which pairs comprises an inlet and an outlet,

a complementarily shaped rotor rotatably carried in said bore and having means forming a plurality of passages therein,

said passages each being arranged to successively interconnect lirst one of said pairs of said openings and then another of said pairs upon rotation of said rotor,

screen means between said one pair of said openings for collecting chips in said passages as each passage interconnects said one pair of said openings,

means for rotating said rotor in said stator,

bearing means for journalling Isaid 'rotor in said stator and for accommodating axial thrust, and

means for moving said bearing means axially to provide axial movement of said rotor in said stator.

2. In a digester system for digesting wood chips,

a rotary yfeeder for liquor and chips comprising a stator having means forming a vertically extending frustoconically shaped bore therein with the larger diameter end of said bore situated at the upper end thereof,

means forming at least two pairs of openings in said stator each of which pairs comprises an inlet and an outlet,

a complementarily shaped rotor rotatably carried in said bore and having means `forming a plurality of passages therein,

said passages each being arranged to successively interconnect rst one of said pairs of said openings and then another of said pairs upon rotation of said rotor,

the length of said rotor being less than the length of said bore to provide a chamber therebetween at the lower end thereof,

screen means between said one pair of said openings for collecting chips in said passages as each passage interconnects said one pair of said openings,

means for rotating said rotor in said stator, and

" conduit means for introducing a pressurized uid into said chamber to counterbalance the effective weight of said rotor and to reduce wear between said rotor and the wall of said bore.

3. In a digester system for digesting wood chips,

a rotary feeder for liquor and chips comprising a stator having means forming a vertically extending frustoconically shaped bore therein with the larger diameter end of said bore situated at the :upper end thereof means forming at least two pairs of openings in said stator each of which pairs comprises an inlet and an outlet,

' a complementarily shaped rotor rotatably carried in said bore and having means forming a plurality of passages therein,

said passages each being arranged to successively interconect rst one of said pairs of said openings and then another of said pairs upon rotation of said rotor, the length of said rotor being less than the length of said bore to provide a chamber therebetween at the lower end thereof, screen means between said one pair of said openings for collecting chips in said passages as each passage interconects said one pair of said openings, means for rotating said rotor in said stator, conduit means for introducing a pressurized uid into said chamber to counterbalance the effective weight of said rotor and to reduce wear between said rotor and the Wall of said bore, and valve means in said conduit means for controlling the pressure of the iluid in said chamber. 4. In a digester system for digesting wood chips, a rotary feeder for liquor and chips comprising a stator having means forming a vertically extending frustoconically shaped bore therein,

means forming at least two pairs of openings in said stator each of which pairs comprises an inlet and an outlet,

a complementarily shaped rotor rotatably carried in said bore and having means forming a plurality of passages therein.

said passages each being arranged to successively interconnect first one of said pairs of said openings and then another of said pairs upon rotation of said rotor, the length of said rotor being less than the length of said bore to provide a chamber therebetween at one end of the bore,

screen means between said one pair of said openings for collecting chips in said passages as each passage interconects said one pair of said openings,

means for rotating said rotor in said stator,

axially adjustable bearing means for journalling said rotor in said stator and for accommodating axial thrust,

1 conduit means for introducing a pressurized uid into said chamber, and

valve means in said conduit means for controlling the pressure of the fluid in said chamber in order to control the axial thrust on said bearing means.

References Cited UNITED STATES PATENTS a S. LEON BASHORE, Primary Examiner.

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