US2744012A - Pulping apparatus - Google Patents

Description

2 Sheets-Sheet 1 Filed April 15, 1953 INVENTOR. ALVA R BY LU N D ATTORNEY.

y 1, 1956 A. BYLUND 2,744,012

PULPING APPARATUS Filed April 13, 1953 2 Sheets-Sheet 2 FIG. 2.

IN V EN TOR.

ALVAR BYLUN 0 BY J 6 "7 ATTORN EY United States Patent Ofiice 2,744,012 Patented May 1, 1!}56 2,744,012 I PULPING APPARATUS Alvar Bylund, Stockholm, Sweden, assignor to A. B. ls)efibrator, Stockholm, Sweden, a corporation of weden Application April 13, 1953, Serial No. 348,231

4 Claims. (Cl. 92'6) This invention relates to a method and apparatus for producing pulp from lignocellulosic raw materials such as wood chips, sawmill waste, straw, bagasse and the like.

The main object of the invention is to provide a method and means for continuously and effectively producing pulp from such raw materials on a very economical basis with respect to time and yield.

It is also an important object of this invention to provide apparatus of the indicated character that is capable of performing its particular advantageous functions in a novel and special manner and in a relatively compact form occupying a minimum of space.

A specific object is to include in an apparatus of this kind a greatly prolonged path for the material under treatment during its transit through the heating and cooking stage.

An ancillary object is to include the step in the method operated in the indicated apparatus, which consists in repeatedly immersing the material being heated and cooked in the treating liquor and drained or freed therefrom therebetween while in transit from the feeding zone to the defibrating zone, in order to produce chemically cooked cellulosic fiber.

Other objects and advantages of my invention will appear more fully in detail as the specification proceeds.

In order to facilitate ready comprehension of this invention for a proper appreciation of the salient features thereof, the apparatus according to the invention is illustrated in the accompanying drawings forming part hereof, and in which:

Fig. 1 is a side elevation of an apparatus according to the invention;

Fig. 2 is a top plan view of the heating and cooking portion of the apparatus illustrated in Fig. 1,'for eflecting a prolonged heating of the pulp; and

Fig. 3 is a front end elevation of the same apparatus as seen from the left in Fig. 1.

Throughout the views, the same reference numerals indicate the same or like parts.

In pulping apparatus of the type operating according to the Asplund system, the lignocellulosic material is received into a rotary feeder from which it is introduced into a predigester and subjected to a cooking treatment at a temperature of at least 212 F. in the presence of steam and where required in the presence of selected chemical reagents and under a steam pressure ranging from 25 to 300 pounds per square inch, after which the treated material is passed to a defibrator for separating the fibers initially softened and released in the cooking stage.

If the cooking treatment is too short in duration, the fibers fail to become softened and initially released, as the intermediate ligneous lamella between the fibers still retain too firm a hold on the latter for proper dissociation and separation of the fibers in the defibrator. Of course, certain expedients have been resorted to for extending the heating and cooking stage, but the apparatus involved has thereby been greatly increased in length not to mention that the apparatus was rendered more bulky and less manageable and less economical in operation. Other disadvantages are also inherent in such expedients, and in addition, the expected advantages of such lengthened apparatus have not been fully realized.

Upon considering this problem, it has occurred to me that the path of travel of the cellulosic raw material from the feeder mechanism and preheater through the heating, cooking and predigesting stage could well be lengthened to a useful extent in a compact and efficient design of the apparatus as a whole. As a result, I have succeeded in originating a method and compact apparatus for adequately heating and cooking raw cellulosic material by prolonged transit from the feeding mechanism and preheater to the defibrator and grinder, which apparatus in addition has advantages of its own definitely contributing to the effectiveness of the method and thorough cooking of the fibers being treated, as will now be set forth more fully.

Hence, in the practice of my invention, and referring again to the drawings, upon a platform 10 supported by a plurality of posts 11 is mounted a substantially horizontal receiver 12 provided internally in known manner with a rotary screw conveyor (not shown) having the shaft 13 thereof projecting out through one end ofpthe receiver and rotatably supported in bearing 14. 1 Upon the projecting end of conveyor shaft 13 is mounted a gear or pulley 15 adapted for engagement with a drive gear or with a drive belt driven by a prime mover of suitable type. Above the receiver is mounted a feeder mechanism 16 having the projecting operating shaft 17 thereof provided with a gear or pulley 18 also adapted to be driven by a gear or belt, etc., driven by a prime mover or the like. This feeder is connected to the receiver through the top thereof, while in turn, a feeding funnel l9 surmounts the feeder for introducing wood chips and the like to the latter from a supply hopper 20 above the funnel.

Adjacent to platform ltl'is located a relatively higher supporting frame, generally indicated at 21, consisting of upright posts 22, upper horizontal girders 23 secured to the upper ends of posts 22 by brazing, welding or riveting said girders to the latter, while a pair of transverse girders 24 are secured to the ends of girders 23. A lower group of horizontal side girders 25 is likewise secured to the intermediate portions of vertical corner posts 22, and togetherwith upper girders 23 and 24, form an elevated supporting unit for a special system of pipes and internal rotary screw conveyors, now to be detailed as the main body of the instant invention.

Thus, the receiver 12 at the end 26 opposite that through which shaft 13 is exposed is closed, but adjacent to this closed end the receiver is through its underside connected to a short depending gravity feed pipe 27 (Fig. 2) which at the bottom opens into the lower end 28 of an inclined semidigester pipe or tube 29 extending from one side of frame 21 to the other and being inclined upwardly to the latter. The lower end 28 of inclined tube 29 is closed by an end cover in the form of a disc 30, while the opposite higher end 31 is similarly closed by a disc shaped cover 32. Beneath upper end 31 of tube 29 is a downwardly directed gravity tube 33 connected thereto at its upper end and its lower end to the lower end 34 of a second inclined semi-digester tube 35 which is symmetrically inclined in the opposite direction tothe first tube 29. The lower end 34 of tube 35 is closed by closure 36 and the opposite higher end 37 by closure 38.

In the system, two further semi-digester tubes 39 and 40 are similarly inclined to first tube 29, alternated with two additional semi-digester tubes 41 and 42 inclined similarly to the second tube 35. The higher ends 37 and 43 of tubes 35 and 41 which are closed by end discs 32'; and 454 are connected by downwardly extending gravity feed tubes 47 and 48 to the lower ends and 46 of op positely inclined semi-digester tubes 39 and 40 which are likewise closed by end discs 49 and a). The higher end 51 of inclined tube 42 is outwardly closed by disc 52, while depending gravity feed tube 53 connects tube 42 with the defibrator 54 disposed beneath the semi-digester tubes upon the bed 55 and serving to deliw .r the coo ed fibers to the outside or to further apparatus (not shown) in known manner.

However, in similar fashion to the gravity feed connection 33 between the higher end 31 of inclined tube 29 and the lower end 34 of tube 35, the higher ends 5-5 and 57 of inclined tubes 39 and 4'3 are connected by downwardly extending gravity feed tubes 58 and 59 to the lower ends 60 and 61 of inclined tubes at and 42 to complete the series. The outer ends 34, 56, 6 57 and 61 of tubes 35, 39, 41, 4t and 12, respectively are closed by discs 62 and 66, which with end disc 32 are provided with reinforced bearings 67 to 72 for screw conveyor shafts 73 to 78 for a series of screw conveyors 79 and 39 (two shown) individually mounted for rotation Within inclined semi-digester tubes 29, 35, 39, 41, it and 42. The opposite end discs 3d, 38, 49, 5t and 52. also serve as bearings for the other ends of the screw conveyor shafts, and all of the discs at both ends are removable for initial insertion of these rotary conveyors and for cleaning, replacement or repairs.

Upon the first mentioned ends of the conveyor shafts exteriorily of bearings 67 to 72 are mounted gears or pulleys 81 to 86 which in alternating order are driven in opposite directions by gears or belts (not shown) driven by a prime mover or the like. Thus, the conveyors 79 in tubes 29, 39 and 40 are rotated in one direction to convey the raw material Within the tubes from the lower ends 28, 45 and 46 thereof to the higher ends 31, 56 and 57, whence the material drops by gravity through gravity feed tubes 33, 58 and 59 into the lower ends 3-i, 6t) and 61 of the other tubes 35, 41 and 42. In these other tubes, conveyors 30 are rotated in the opposite direction in order to feed the material along through tubes 35, 41 and 42 from the lower ends 34, 6d and 61 thereof to the higher ends 37, 43 and 51. The material being treated drops from the higher ends 37 and 43 through gravity feed tubes 47 and 48 into the lower ends 4-5 and 46 of tubes 39 and 4t), and from the higher final end 51 of the series of tube 42 through gravity feed tube 53 to the defibrator are already mentioned.

Thus, when all of the screw conveyors are rotated and the raw cellulosic material fed into the apparatus, this material will be propelled from the lower end 23 of the first tube 29 in which it is received by gravity through vertical tube 27 from receiver 12, being then dropped from the higher end 31 of tube 29 through gravity feed tube 33 into the lower receiving end 34 of tube 35. In this tube. the material is conveyed to the higher end 37, whence the same material drops through gravity feed tube .7 into lower receiving end 45 of tube 39, and so on in a continuous operation.

As best seen in Fig. 3, in the intermediate portions of the inclined tubes 29, 35, 39, d1, 40 and 42 are provided with normally closed outlets 87, 88, etc., for tapping excess or spent chemical liquors from the tubes. In these latter, the liquor may well extend substantially halfway up in each of the inclined tubes, and obviously, during operation, the material being treated first drops through the gravity feed tubes into submergence in the liquor in the lower end of each inclined tube, but is then conveyed by the screw conveyor upwardly into the higher end of the respective inclined tube above the level of the liquor so as to be virtually drained of the liquor before plunging again into the liquor in the lower end of the next inclined tube in the series. Thus, the material is repeatedly submerged and drained of chemical liquor while traveling through a prolonged heating and chemical cooking stage. The heated material is then grounded in the defibrator 55 and discharged from the latter through delivery pipe 89 by means of a blow valve or by a reciprocating valve of the type shown. in Asplund Patent No. 2,608,892, for further treatment and finishing. The defibrator has the shaft 90 thereof rotatably mounted in bearings 91 and 92, while a pulley 93 on this shaft is connected to driving pulley 94 of a motor 95 by a belt 96, the defibrator and its drive and operation forming no actual part of this invention but being included to complete the environment of the invention to display its particular functions and utility. Similar remarks apply to the chip hopper, funnel, feeder mechanism 16 and receiver 12.

In order to provide the system with the proper heat and pressure, the first item being a temperature of at least 212 F. and the other item amounting to a pressure ranging from 25 to 300 pounds, a main steam pipe 97 has a series of individual branches 9810 for conducting live steam from a boiler (not shown) to each of the inclined pipes and receiver 12, the supply being controlled by valves and 106.

As partly indicated in broken lines in Fig. 1, and upper belt 107 may simultaneously engage conveyor pulleys 35, 83 and 87 to rotate them counterclockwise from a drive pulley (not shown), and in similar fashion, a second belt 108 simultaneously engaging lower pulleys 82, 84 and 86 may rotate them clockwise from a drive pulley (also not shown). The inclined pipes or tubes may be suspended or secured to frame 21 by brackets 169, 110, and 111 and lower brackets 112, 113 and 114 by brazing or welding the same thereto, if desired, but other means may also be used.

It may also be noted that the chemical reagents or liquors used may be introduced at various points in the inclined tubes and the general concentration thereof maintained throughout the system. Also, liquor may be withdrawn and/or renewed according to the dilution occasioned by condensation of the steam entering the system.

The finally cooked and separated fibers delivered from the defibrator 54 through delivery pipe 89 are suitable for use in the following fields:

Wallboard, such as hardboard and insulating board Chip board Paper pulping for corrugating and liner board Paper pulp which can later be subjected to bleaching for fine paper purposes.

By changing the length of heating time and the strength of the chemical reagents, it is possible to produce a great variety of fibres which can be used for the abovementioned purposes, and many others.

The chemicals to be employed can either be of the alkaline or acid type. Regular caustic soda or the various combinations employed in normal sulphate cooking can be used, as well as such acids as are employed in the sulphite industry; also salts such as neutral sodium sulphite or any kind of chemicals which have been found suitable for pulping purposes by ordinary means.

Although the invention has been directed specifically in conjunction with a rotary feeder mechanism, it will be understood that the conventional series feeder or plunger feeder can also be employed. However, for slippery material and material which possesses a very low friction co-efiicient, the rotary feeder or pocket valve feed-in apparatus is preferred.

Manifestly, variations may be resorted to, and parts and features may be modified or used without others within the scope of the appended claims.

What is claimed is:

1. In an apparatus for producing pulp comprising a closed system defining a path of flow for the material to be treated, a feeding device for introducing material into said path of flow, abrading means for the material interposed in said path of flow and a discharge device for removing the treated material from said path of flow; means for subjecting the raw material to a prolonged treatment in the course of flow from said feeding device to said abrading means, said means comprising a series of interconnected oppositely inclined tubes with their axis of inclination in a substantially horizontal plane, the lower end of the first one of said tubes being connected to said feeding device and the upper end of the last one of said tubes being connected to said abrading means and the upper ends of the intermediate ones of said tubes being connected to the lower end of the adjoining tube,

the tubes being arranged in two connected groups, one of said groups consisting of a plurality of said tubes which all incline in the same direction and which are all on the same horizontal level, the second of said groups consisting of tubes which all incline in an opposite direction to those in the first group and which are all on the same horizontal level, and conveyor means within said tubes for transporting the material from said lower ends to said upper ends.

2. In an apparatus for producing pulp comprising a closed system defining a path of flow for the material to be treated, a feeding device for introducing material into said path of flow, abrading means for the material interposed in said path of flow and a discharge device for removing the treated material from said path of flow; means for subjecting the raw material to a prolonged treatment in the course of flow from said feeding device to said abrading means, said means comprising a series of interconnected oppositely inclined tubes with their axis of inclination in a substantially horizontal plane, the lower end of the first one of said tubes being connected to said feeding device and the upper end of the last one of said tubes being connected to said abrading means and the upper end of the intermediate ones of said tubes being connected to the lower end of the adjoining tube, the tubes being arranged in two connected groups, one of said groups consisting of a plurality of tubes which incline in the same direction and which are all on the same horizontal level, the second of said groups consisting of tubes which incline in an opposite direc tion to those in the first group and which are all on the same horizontal level, whereby the path of flow of the material through the tubes in the first group crosses the path of flow of the material through the tubes in the second group, conveyor means within said tubes for transporting the material from said lower ends to said upper ends and means for introducing steam under pressure to said tubes.

3. In an apparatus for producing pulp comprising a closed system defining a path of flow for the material to be treated, a feeding device for introducing material into said path of flow, abrading means for the material interposed in said path of flow and a discharge device for '6 removing the treated material from said path of flow; means for subjecting the raw material to a prolonged treatment in the course of flow from said feeding device to said abrading means, said means comprising a series of interconnected oppositely inclined tubes with their axis of inclination in a substantially horizontal plane, the lower end of the first one of said tubes being connected to said feeding device and the upper end of the last one of said tubes being connected to said abrading means and the upper end of the intermediate ones of said tubes being connected to the lower end of the adjoining tube, the tubes being arranged in a horizontal row in side-by-side relationship, with a first group of the tubes in said row all inclining in the same direction and being all on the same horizontal level, and a second group of tubes in said row alternating with those of the first group and inclining in a direction opposite to the direction of inclination of the tubes in said firstgroup and being all on the same horizontal level, the tubes'in the first group extending angularly across those in the second group, a treating liquor in said lower ends, and conveyor means within said tubes for transporting the material from said lower ends to said upper ends, the degree of inclination of said tube being such that the raw material will be submerged in said treating liquor while being conveyed through the lower portion of said tube and will be substantially free of said treating liquor upon its arrival at said upper end.

4. In an apparatus for producing pulp comprising a closed system defining a path of flow for the material to be treated, a feeding device for introducing material into said path of flow, abrading means for the material interposed in said path of flow and a discharge device for removing the treated material from said path of flow; means for subjecting the raw material to a prolonged treatment in the course of flow from said feeding device to said abrading means, said means comprising a series of interconnected oppositely inclined tubes with their axis of inclination in a substantially horizontal plane, the lower end of the first one of said tubes being connected to said feeding device and the upper end of the last one of said tubes being connected to said abrading means and the upper end of the intermediate ones of said tubes being connected to the lower end of the adjoining tube, conveyor means within said tubes for transporting the material from said lower ends to said upper ends and means for introducing steam under pressure to said tubes, said tubes being symmetrically arranged in horizontal side-by-side relationship with said lower ends and said upper ends at substantially the same respective levels.

References Cited in the file of this patent UNITED STATES PATENTS 287,980 Thompson Nov. 6, 1883 1,110,233 Rice Sept. 8, 1914 1,982,130 Wollenberg Nov. 27, 1934 2,425,024 Beveridge Aug. 5, 1947 2,542,801 De La Roza Feb. 20, 1951 2,623,820 Messing Dec. 30, 1952

Claims (1)

1. IN AN APPARATUS FOR PRODUCING PULP COMPRISING A CLOSED SYSTEM DEFINING A PATH OF FLOW FOR THE MATERIAL TO BE TREATED, A FEEDING DEVICE FOR INTRODUCING MATERIAL INTO SAID PATH OF FLOW, ABRADING MEANS FOR THE MATERIAL INTERPOSED IN SAID PATH OF FLOW AND A DISCHAGE DEVICE FOR REMOVING THE TREATED MATERIAL FROM SAID PATH OF FLOW; MEANS FOR SUBJECTING THE RAW MATERIAL TO A PROLONGED TREATMENT IN THE COURSE OF FLOW FROM SAID FEEDING DEVICE TO SAID ABRADING MEANS, SAID MEANS COMPRISING A SERIES OF INTERCONNECTED OPPOSITELY INCLINED TUBES WITH THERIR AXIS OF INCLINATION IN A SUBSTANTIALLY HORIZONTAL PLANE, THE LOWER END OF THE FIRST ONE OF SAID TUBES BEING CONNECTED TO SAID FEEDING DEVICE AND THE UPPER END OF THE LAST ONE OF

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