US3034576A

US3034576A - Continuous cooker

Info

Publication number: US3034576A
Application number: US767620A
Authority: US
Inventors: Edgar G Putnam; Fred G Greaves
Original assignee: NAT BANK OF COMMERCE OF SEATTL
Current assignee: NAT BANK OF COMMERCE OF SEATTL; NATIONAL BANK OF COMMERCE OF SEATTLE
Priority date: 1958-10-16
Filing date: 1958-10-16
Publication date: 1962-05-15
Anticipated expiration: 1979-05-15

Description

May 15, 1962 E. G. PUTNAM ETAL CONTINUOUS COOKER Filed Oct. 16, 1958 INVENTOR. FRED G. GREAVES EDGAR G. PUTNAM Fm ESO x030:

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May 15, 1962 E. G. PUTNAM ET AL CONTINUOUS COOKER 2 SheetsSheet 2 Filed Oct. 16, 1958 INVENTOR.

FRED G. GREAVES BY EDGAR G.PUTNAM @MM United States atet hhce 3,634,575 Patented May 15, 1962 3,034,576 CQNTINUOUS COGKER Edgar G. Putnam and Fred G. Grea /es, Seattle, Wash, assignors, by mesne assignments, to National Bank oi Commerce of Seattle, Seattle, Wash, a corporation of Washington Filed Get. 16,1958, Ser. No. 7157,6259 29 Claims. (Cl. 162237) This invention relates generally to improved apparatus for effecting continuous chemical treatment and cooking of various fibrous materials and has particular application to the continuous cooking under pressure of material such as wood chips in steam-heated chemical liquor during the manufacture of wood pulp.

One of the objects of the invention is to provide an improved continuous cooker by which chemical concentration at various stages of the cooking cycle can readily be more accurately controlled.

Another object is to provide such a cooker which is constructed of demountable units permitting ease of rearrangement for handling various types of raw products and varying required end results so that pulp of smaller capacity are madeeconomically possible due to the ability of the mill to furnish pulps for a greater variety of markets than can be done with conventional mills.

The invention also aims to provide a cooker whereby a three-stage cook is possible in a single vessel, and namely a cycle having continuous steam, liquor-impregnation, and vapor phases.

Still another object is to provide a cooker wherein variations in pulp consistency are possible to a greater degree and which has a lower chemical consumption- With yet additional objects and advantages .in view which, with the foregoing, will appear and be understood in the course of the following description and claims, the invention consists inthe novelconstruction and in the adaptation and combination of parts hereinafterdescribed nd claimed.

in the accompanying drawings:

FIGURE l-is a semi-diagrammatic.elevational sectional view of one form of our improved cooker;

FIG. 2 is a similar view of another form of the cooker.

FIG. 3 is an enlarged view of the lower end portion of the modified cooker; and

FIG. 4 is a horizontal sectional view taken as indicated by the line 4-4 of FIG. 3.

Referring to the drawings it is seen that our continuous cooker is generally U-shaped, and that theiirst embodiment has inlet and outlet towers which extend upwardly from the ends of a central section 19 at elbows 11-12. The inlet tower may be oftwo piece construction, the upper half 13 of which is'provided with an inlet branch 14 which intersects therewith a short distance above the lower half 15 of the tower. Numeral 15 is applied to the outlet tower and it will be noted that an elbow 17 leads from the upper end thereof into an outlet branch 18 which extends horizontally.

The wood chips to beprocessed are fed to the inlet branch 14 by a feed valve 26 and the processed fibers are discharged from the outlet branch through an egress neck 1 into a discharge valve 22. These valves 26, ZZ-must be capable of continually feeding and discharged material without loss of pressure and may be of the type shown in U.S. Patent No. 2,816,693.

For conveying material through the inlet tower there is provided a feed screw 23 which cantilevers downwardly from the top section of the inlet 13 to the mouth of the elbow 11. Alined bosses 24-25 project oppositely from the elbows 1l12 to receive the ends of a second feed screw 26 which extends through the center section it} of the cooker. The feed conveyor at the inlet is complemented in the outlet tower by an upwardly working screw conveyor 27 which is cantilevered downwardly from a boss extension 28 provided on the upper elbow 17. Material is fed from this elbow through the outlet branch 18 to the egress neck 21 by a discharge feed screw 30 journaled in a cover plate 29 at the free end of the branch. Suitable bearings and seals are provided at the top of the inlet section 13, in the bosses 24 25 and Z8, and at the outer end of the outlet branch 18 for the respeotive ends of the

screw conveyor sections

23, 26, 2.7 and 3%). A respective variable speed drive motor 31 is coupled to the conveyor sections so that each of these can be driven independently of the others at selected difierent speeds.

For some applications it may be desirable to rearrange portions of the cooker and for this reason and for ease of erection the various afore-described sections are connected together by bolts 32 which pass through neck flanges 33 which are welded into position at the ends of the various sections. All parts of the cooker which are to be in contact with the liquor are made corrosion resistive. It Will be noted that the outlet section it; is equipped with a cylindrical strainer 34 to prevent the fibers from clogging a staggered set of liquor outlet pipes 35.

The outlet pipes 35 are at various levels and each has an independent control valve 36. Headers 37 lead from the outlet pipes to a liquor outlet line 38 from whence the liquor can be dumped or recirculated.

'Ihe fibrous material is first subjected to liquor in the inlet branch 14 by means of two liquor pipes 49 discharging at opposite sides thereof. Liquor impregnation also occurs in the lower half 15 of the inlet tower by means of a grou of vertically staggered feed pipes 41 arranged similarly to the outlet pipes 35. These inlet pipes 41 have control valves 42 and are fed from inlet headers 4-3 which are supplied from an inlet line 44. Thus it is seen that both the inlet and outlet towers have manifold arrangements which permit the liquor level to be closely controlled for various types of cooks.

A third liquor manifold is provided for the center section ll) of the cooker.- This manifold also has a plurality of inlet pipes 46 staggered along its length which connect to a pair of headers 47 supplied from a feed line 48. Control valves 49 are provided in the pipes 46 and this arrangement permits regulation of the chemical concentration as the pulp travels along. Steam and Water for the cook may be supplied through pipes 5tl51 lo- As the material then passes into the elbow it it comes under the influence of the center feed screw 26 which causes it to progress along the length of the center cooker section 1%. During this part of its travel the material is subjected to a fresh supply of liquor entering through the pipes 47 as controlled by the valves 46. This control makes it possible to maintain a substantially constant chemical concentration when such is desired. The impregnated material next passes into the elbow 12 to be caught up by the outlet feed screw 27 which causes it to move upwardly through the outlet tower 16 to the elbow 17. During this time the cylindrical screen 34 prevents the fibers from passing outwardly with the liquor through the outlet pipes 35. The valves 36 are used to control the level of the liquor in the outlet tower and as the feed screw 27 carries the material above this level the material commences a vapor cook. Such continues as the material is pushed through the elbow 17 to be acted upon by the screw 36 in the outlet branch 13. The treated material then drops through the egress neck 21 into the outlet valve 22 which discharges it for further treatment.

The fact that the cooker of the present invention has no tie between its upper ends affords a variable pressure depending upon the plug effect of the material in the center feed screw 26. This plug effect is adjustable by varying the speeds of the

screws

23, 26, and 27 relative to one another. Also, a three-stage cook is possible in the cooker by using a short steaming time at the beginning of the cycle, and namely above the level of the liquor in the inlet tower, this level being determined by the valves 42. The second stage, and namely that of impregnation, commences in the lower section of the inlet tower and continues through the center section 1%) for completion partway up the outlet tower 16, this depending of course upon the liquor level as set by the outlet control valves 36. As before mentioned, at this time the material undergoes a vapor phase cook.

It can be readily seen that variable pitch or tapered screws can be used as Well as the illustrated standard pitch screws to vary the conditions of cooks for varying types of raw products and varying required results. The latter is also made possible by the use of the demountable units in building the cooker. For example, the outlet tower 16 and its manifold can be interchanged with the lower inlet tower section 15 and its feed manifold should it be desired to have the liquor moving in counterfiow to the travel of the fibrous material through the cooker. In this case the outlet line 38 would be made the inlet while the inlet line 44 would become the outlet.

The variable speed drives 31 on the conveyor screws enable variations in cooking time which will make possible any type of cook from a straight steam or water cook to a complete chemical cook to produce a higher yield of high grade chemical pulp. This can be done without variations in tube length. However, it will be realized that tube lengths can be easily changed because of the flange connections at the various cooker sections. The various liquor manifolds can be used to supply fresh liquor or recirculated liquor depending upon the desired results.

Thus it is seen that the flexibility of the continuous cooker of the present invention enables the economic construction of pulp mills of smaller capacity than is now possible and gives the mill the ability to furnish pulps for a greater variety of markets than can be done with conventional apparatus.

In FIG. 2 we have illustrated a simplified cooker embodying our invention in which a central cooker section is substantially eliminated. The inlet and outlet towers of this modified embodiment diverge at an acute angle rather than being in parallel relation and each are of two part construction quite similar to the inlet tower of the first embodiment. The lower sections 6% 61 of the inlet and outlet towers are joined by

flanges

62, 63, respectively, to a pair of bottom T-

sections

64, 65. These T-sections have their legs connected together at flanges 66 to make a short center section interconnecting the towers. The extreme lower ends of the T-sections have end plates 67 for closing the towers and holding suitable bearings and seals for feed and discharge screw conveyors 686. These conveyors extend the full length of the towers and are journaled at the top on end plates 71-72 mounted at the upper ends of top inlet and outlet tower sections 73-74. 7

Intermediate their ends these top tower sections have upwardly and downwardly extending inlet and outlet branches 7576, respectively, which are supplied and evacuated by feed and discharge valves 7778 such as those aforementioned. Variable speed drives 80 are also provided for the conveyors. The liquor, steam and water feeds to the inlet tower are the same as those described for the inlet tower of the first embodiment and hence identical numerals have been applied to the inlet pipes thereof. Similarly, the outlet section 61 is provided with the same screen and discharge manifold as the cooker section 16 of the first embodiment. Thus, a generally U-shaped cooker is provided which gives results very similar to that which can be obtained by use of the first embodiment with its center section and screw conveyor 26 removed and the elbows 11 and 12 thereof directly connected together. This arrangement shortens the impregnation phase of the cycle but gives excellent results in a wide range of cooks. The fiber material after completing its cook drops from the upper end portion of the discharge conveyor 69 into the outlet branch 76 for dischargeby the outlet valve 78.

The advantages of the invention, it is thought, will have been clearly understood from the foregoing detailed description. Minor changes will suggest themselves and may be resorted to without departing from the spirit of the invention, wherefore it is our intention that no limitations be implied and that the hereto annexed claims be given a scope fully commensurate with the broadest interpretation to which the employed language admits.

What we claim is:

1. In a continuous cooker, a generally U-shaped cooking vessel having upright ingress and egress sections sealed at the top from one another and from the atmosphere and interconnected at the bottom by a center section, respective screw conveyors driven externally of said vessel and extending through the major part of the length of said ingress and egress sections for moving material downwardly toand upwardly from said center section, a material inlet branch intersecting said ingress section below the top of the latters conveyor, a material outlet branch intersecting said egress section at the top thereof, continuous material handling feed and discharge valves operatively connected to said inlet and outlet branches, respectively, and means for pressurizing said vessel and introducing liquor thereto.

2. In a continuous cooker, a generally U-shaped cooking vessel having upright ingress and egress sections sealed at the top from one another and from the atmosphere and interconnected at the bottom by a center section, respective screw conveyors driven externally of said vessel and depending into said ingress and egress sections from journal mountings at the top thereof for moving material downwardly to and upwardly from said center section, a screw conveyor in said center section journal-mounted at the ends of the latter and driven externally of the vessel for moving material from the ingress to the egress section, a material inlet branch intersecting said ingress section below the top of the latters conveyor, a material outlet branch intersecting said egress section at the top thereof, continuous material handling feed and discharge valves operatively connected to said inlet and outlet branches, respectively, and means for pressurizing said vessel and introducing liquor thereto.

3. In a continuous cooker, a generally U-shaped cooking vessel having upright ingress and egress sections sealed at the top from one another and from the atmosphere and interconnected at the bottom by a center section, respective independent conveyor means driven externally of said vessel and extending through a major part of the length of said ingress and egress sections for moving material downwardly to and upwardly from said center section, feed means operatively associated with said ingress section for continuously feeding material thereto at a level below the top of the conveyor means therein, discharge means operatively associated with said egress section for continuously withdrawing material from the top thereof, and means for pressurizing said vessel and introducing liquor thereto.

4. In a continuous cooker, a generally U-shaped cooking vessel having upright ingress and egress sections sealed at the top from one another and from the atmosphere and interconnected at the bottom by a center section, respective independent conveyor means driven externally of said vessel and extending through a major part of the length of said ingress and egress sections for moving material downwardly to and upwardly from said center section, additional conveyor means driven externally of said vessel and extending through the length of said center section for moving material from the ingress to the egress section, feed means and discharge means operatively associated, respectively, with said ingress and egress sections for continuously feeding material to the vessel near the top of the ingress section and withdrawing material near the top of the outlet section, and means for pressurizing said vessel and introducing liquor thereto.

5. In a continuous cooker, a generally U-shaped cooking vessel having upright ingress and egress sections sealed at the top from one another and from the atmosphere and interconnected at the bottom by a center section, respective independent conveyor means driven externally of said vessel and extending through a major part of the length of said ingress and egress sections for moving material downwardly to and upwardly from said center section, feed means operatively associated with said ingress ection for continuously feeding material thereto, a material outlet branch intersecting said egress section by one of its ends, a continuous material handling discharge valve connected to the other end of said outlet branch, conveyor means in said outlet branch for moving material from said egress section to said discharge valve, and means for pressurizing said vessel and introducing liquor thereto.

6. In a continuous cooker, a generally U-shaped cooking vessel having upright ingress and egress sections interconnected at the bottom by a center section and otherwise free of interconnection, respective independent conveyor means extending through a major part of the length of said ingress and egress sections for moving material downwardly to and upwardly from said center section, a downwardly sloping material inlet branch intersecting by its lower end said ingress section below the top of the latters conveyor means, a continuous material handling feed valve connected to the top of said inlet branch, discharge means operatively associated with said egress section for continuously withdrawing material therefrom, and means for pressurizing said vessel and introducing liquor thereto.

7. The continuous cooker of claim 6 in which a liquor inlet line joins said material inlet branch.

8. The continuous cooker of claim 6 in which steam and water lines join said ingress section at a level higher than the lower end of said inlet branch.

9. The continuous cooker of claim 6 in which said discharge means comprises an outlet branch intersecting with the top portion of said egress section, a continuous material handling discharge valve operatively connected to said outlet branch, and a screw conveyor operatively mounted in said outlet branch for moving material from said egress section to said discharge valve.

10. The continuous cooker of claim 6 in which said conveyor means in said ingress section comprises a screw conveyor cantilevering downwardly from a journal-mounting at the top of the ingress section.

11. The continuous cooker of claim 6 in which said ingress and egress sections diverge from the ends of said center section and separated at the top as viewed endwise of the latter and in which said center section is considerably shorter than said ingress and egress sections.

12. In a continuous cooker, a generally U-shaped cooking vessel having upright ingress and egress sections intercomected at the bottom by a center section, respective independent conveyor means extending through a major part of the length of said ingress and egress sections for moving material downwardly to and upwardly from said center section, feed means operatively associated with said ingress section for continuously feeding material thereto, an outlet branch having one of its ends connecting by an elbow with the top of said egress section, a continuous material handling discharge valve operatively connected with said outlet branch near the other end thereof, conveyor means operatively mounted in said outlet branch for moving material to said discharge valve, and means for pressurizing said vessel and introducing liquor thereto.

13. The continuous cooker of claim 12 in which said conveyor means in the egress section comprises a screw conveyor cantilevering downwardly from a journal-mount ing at the top of the egress section, and in which said conveyor cantilevering toward said egress section from a journal-mounting of said other end of the outlet branch.

14. In a continuous cooker, a generally U-shaped pres surized cooking vessel having upright ingress and egress sections interconnected at the bottom by a center section and otherwise free of interconnection, respective screw conveyors in said ingress and egress sections cantilevering downwardly from journal-mountings at the tops thereof, a screw conveyor in said center section journal-mounted at the ends thereof, feed means for delivering material to the conveyor in said ingress section, discharge means for withdrawing material from said egress section, and means for turning said conveyors such that delivered material is transported through said vessel to said discharge means.

15. The continuous cooker of claim 14 in which said center section has multiple valve-controlled liquor inlets spaced along its length.

16. The continuous cooker of claim 15 in which said egress section has multiple valve-controlled screen-covcred liquor outlets spaced along its length for controlling the liquor level in said vessel.

17. In a continuous cooker, a generally U-shaped cooking vessel having upright ingress and egress sections interconnected at the bottom by a center section and separated at the top, respective independent conveyor means eX- tending through a major part of the length of said three sections, feed means and discharge means operatively associated, respectively, with said ingress and egress sections for continuously feeding material to said conveyor means in the ingress section near the top thereof and for continuously discharging material from the top of said egress section, means for pressurizing said vessel, means for supplying liquor to said vessel, and control means for regulating the liquor level in said egress section.

18. The continuous cooker of claim 17 in which said egress section has its inner wall covered by a screen and has multiple valve-controlled liquor outlets disposed along the length thereof for controlling the liquor level.

19.,The continuous cooker of claim -17 in which said liquor supplying means includes multiple liquor. inlets disposed along the length of said ingress section.

20. The continuous cooker of claim 17 in which said liquor supplying means includes multiple valve-controlled liquor inlets disposed along said ingress and center sections, and in Which said egress section has valve-controlled screen-covered liquor outlets at various levels for controlling the liquor level in said vessel.

References Cited in the file of this patent UNITED STATES PATENTS Braun Dec. 12, Dunbar Sept. 14, Messing et a1. Aug. 12, Richter Jan. 18, Lawton et al. July 22,

FOREIGN PATENTS Austria May 10, Germany Aug. 17,

Great Britain Oct. 22,