US2893909A - Combined digestion and refining of paper pulp - Google Patents

Description

Y 7, 1959 J. c. SHOUVLIN ETAL- 2,893,909

COMBINED DIGESTION AND REFINING OF PAPER PULP Filed June 9. 1954 2 Sheets-Sheet l INVENTOR. JOSEPH C. SHOUVLIN Y MHRVIN E'. GINBVEN B 1959 J. c. SHOUVLIN ET AL 2893309 COMBINED DIGESTION AND REFINING OF PAPER PULP Filed June 9, 1954 2 Sheets-Sheet 2 INVEN TOR. JOSEPH C.Suouv1.m

Mnavm E.Gmnve- BMW W commits nroEsrroN RE'riNnsG or PAPER PULP Joseph C. Shbuvlin andMarvin E; Ginaven, Springfield,

Ohio, assignors to The Bauer Bros. Company, Springfield, "Ohio, acorporation-of Ohio Application Jlllle 9, 1954, SerialNo; 435,466

Claims. (Cl. 162-17) This invention relates to theart of pulping and refining, and more particularly to methods and apparatus useful in the treatment of 'afibrous material such as wood chips.

The object of the invention is to'simplify the construe-I tion as well as the means and tmode" of operation of pulp refining systems, whereby such systems may'not only be economically manufactured, but will be more efficient and satisfactory in use, adaptable tea-wide variety of applications,having relatively 'few parts and be unlikely to get out of repair.

It is a further object of the invention to introduce a generally new step in the treatment 'of fibrousmaterials, it being proposed to subject cooked but unrefined mate rial to action in a press so as to extract 'residualcooking liquid from the material and to partly-defiber the material.

It is a further object, in this connection, to materially reduce the volume of washwater required to neutralize and carry off acids and liquors" generated in the cooking process, it *being of course an' acce'ssory object in this regard to make. the disposal of the waste liquids relatively easy and harmless:

A further object of the invention is to remove residual chemicals and acids from the cooked fibrousmaterial in a highly concentrated form in which it rn'ay have utility as a by-product of the refining-process.

Stillanother object of the invention'is to make the subsequent defibering process (as in a 'disc type mill) easier and less costly in power" consumption 'by effecting softening and preliminary defibering of'the materialin" conjunction with the procms ofliquid extraction.

Still another object of the inv ention is to mount the cooker or digester and press in close association with one another in such manner that the material from the cooker passes into the press without loss of pressure and heat, it being proposed to substitute and make use of the press itself for the conventional outlet control of the cooker.

Still further, it is an object of the invention to provide a method and apparatus for pulping and refining making use of a screw type press developing very high pressures, and making use of the heat generated by these high pressures to soften the lignin, to aid the defibering process.

A further object of the invention is the removal of residual liquids and moisture in the fibrous material which obviates or reduces the need for Washing of the pulp fibers. Such moisture extraction also eliminates subsequent drying operations in the case of semi-dry structural board manufacture. Y

Another object of the invention is to provide a generally new method of and apparatus for defibering, including the use of a press for heatingand partly defibering a fibrous material and a refiner supplied withmaterial from saidpress. v

Stillanother object' of the' inve'ntion is to provide in the"'art of pulping and refininga press for treating a fibrous materialbyapplying com ressive and" shearing some) Patented July 7, 19519 forces thereto, whereby to perform the several functions of liquid extraction, partial defibering and heating.

A further object of the invention is to provide a pulp refining system possessing the advantageous structural features, the inherent meritorious characteristics and the mode of operation herein mentioned.

With the above primary and'other incidental objects in view as will more fully appear in the specification, the invention intended to be protected by Letters Patent consists of the features of construction, the parts and combinations thereof, and the mode of operation, as hereinafter described or illustrated in the accompanying drawings, or their equivalents.

Referring to the drawings, wherein is found one but obviously not necessarily the only embodiment of the invention,

Fig. 1 is a view, in diagram, of a part of a pulp mill installation, in accordance with the illustrated embodiment of the present invention,

Fig. 2 is a view in longitudinal section, partly diagrammatic in form, of a screw press introduced in pulp mill work in accordance with the teaching of the instant inven tion, and

Fig. 3 is a view in cross section taken substantially along the line 33 of Fig.2.

Like parts are indicated by similar characters of reference throughout the several views.

Referring to the drawings, the material tobe treated is introduced into the inlet 11 of a conveyor unit 12, and carried by the unit 12 in overlying relation to a digester tank 13. The material is then admitted to the upper end of such tank by way of a connector pipe 14, under con trol of valves 15 and 16 installed therein.

Steam is admitted to the digester 13 by way of a conduit 17, and chemicals by way of a conduit 18. An exhaust or pressure relief line 19 communicates with the digester 13 by way of connector 14, and has a control valve 21 interposed therein.

At its lower end the digester 13 communicates, as through a connector pipe 22, with the inlet end of a screw press 23, the opposite or outlet end of which discharges through a conduit 24 to a disc type refiner 25. The digester 13 empties directly into the press, the connector 22 being joined at its one end in a fiuid tight manner to the digester and similarly connected at its opposite end to the body of the press.

Within the digester the fibrous material is in substance cooked at an elevated temperature on the order of 212 and higher, and at an elevated pressure on the order of psi. and higher. A hydrolyzing action occurs, releasing acids. Various chemicals are added to control the rate of reaction and to inhibit corrosion, and it has in the past been necessary to extensively wash the cooked material to remove the acids and the chemicals. Practically all the end products utilizing the pulp material are required to be substantially chemical free.

According to the present inventive concept, however, the pulp and the cooking liquor are allowed to pass. out of the bottom of the digester and into the press 23 while still heated and under continuing super-atmospheric pressure. Within the press, in a manner to be described, the admitted material is subjected to still greater pressures and to shearing forces, resulting in an extraction of liquids and a partial defibering of the material.

The refiner 25 may, as indicated, be of the rotary disc type and performs its usual function in mill operations exceptthat the efiiciency' and quality of its work are improved. Thus, the press 23 represents a means for feeding pulp material to the machine 25 at a controlled rate. T he'high pressures and shearing forces exerted on the material in the press further have the effect of softening the lignin in fibrous material, and this in conjunction with the preliminary defibering sible a better reduction of material in the refiner. and at less cost in power consumption.

Referring to Figs. 2 and 3, the press 23 is a screw press which includes body members 26 supporting a cylinder 27 comprising a plurality of bars 28 between which free and released liquid may escape from the press; The cylinder 27 and aligned openings in the body 26 define a through longitudinal passage 29, one end of which communicates with a radial inlet opening 31 and the other end of which terminates in an outlet opening 32. Flow through the latter is regulated by a sleeve 33 longitudinally adjustable in a housing. 34 bolted to the outlet end done in the press, makes posof the press. An opening 35 in the housing 34 has the conduit 24 connected thereto, by which the discharged material is conducted to the refiner 25.

The aforementioned connector 22, or as shown in Fig. 2 another connector 36 embodying a feeding vane 37, is

mounted on the press body 26 in alignment with the inlet 31. Pulp material entering inlet 31 is fed through the passage 29 by a screw assembly including disconnected, axially aligned sleeves 38 and 39 formed with exterial helical threads 41 and'42, respectively. A shaft 43 extends through and beyond the passage 29, having a hearing at its one end in the sleeve 33 and at its other end in a housing 44 attached to the inlet end of the press. The sleeve 38 is rotatably mounted on the shaft 43, while the sleeve 39 is secured thereto for unison rotation. The described other end of the shaft 43 is constructed with splines 40 or the like and arranged for cooperative engagement with suitable power rotating means, while the sleeve 38 is separately rotatable as by means including a sheave 45 thereon. The arrangement of parts is such that the sleeve 38 may be turned faster than the sleeve 39, thus insuring that that part of the screw assembly beyond the .sleeve 38 is adequately supplied with pulp material, the length of the sleeve 38 being short in relation to the overall length of the screw assembly.

The sleeve 39 is formed with a longitudinal series of spaced apart, frusto conical portions 46 which may, as

indicated, be progressively greater in diameter and which in conjunction with the cylinder 27 define spaced apart areas 47 of low clearance separated by chambers 48 of relatively large clearance.

Diametrically opposed, longitudinally extending, means 49 are installed in the cylinder 27 and have longitudinally spaced apart abutments 51 extending radially into the cylinder substantially in line with the portions 46, as 'Well as a pair of abutments 52 extending into the cylinder in advance of the series of portions 46.

The incoming pulp material is fed into the passage 29 by the sleeve 38 and packed thereby onto the first adjacent screw threads of the sleeve 39, under conditions of rising pressure. The material tends to rotate with the sleeve 39, although this is in part inhibited by the abutments 52 with the result that there is some shearing action on the pulp. At the same time, the material is advanced toward and into the first area 47 of low clearance, retarding the rate of flow and again materially raising the pressure to which the material is subjected, it being contemplated in this connection that the developed pressures in the press shall be on the order of six to ten thousand pounds per square inch. Under these conditions the material is compacted in the area 47, forming in effect a plug the tendency of which to rotate with the sleeve 39 is inhibited by the abutments 51. The screw threads 42 continue to force pulp material upon such plug, and, as the forward movement of the material is slowed, the threads twist and partly defiber the material. The applied forces expel the compacted material from the area of low clearance into the next adjacent chamber 48 where the high pressures are to a degree released, and then reapplied as the material is picked up by the threads 42 and compacted into the next succeeding area 47. The alternating cycles of compression and reduction of pressure are repeated throughout the series of frusto-conical portions 46, with the result that there is discharged from the. press a dry partly defibered material which may be conducted as shown to a refiner 25 for further reduction, or used in its discharged form in the making of pressed wood boards and the like. It is understood, in this connection, that the action of the press is such as toexpress a substantial part of the liquid as shown diagrammatically at 50, Fig. 1, from the fibrous material (approximately 70%) and also to generate added heat having a softening effect on the material as before described;

From the above description it will be apparent that there is thus provided a device of the character described possessing the particular features of advantage before enumerated as desirable, but which obviously is susceptible of modification in its form, proportions, detail construction and arrangement of parts without departing from the principle involved or sacrificing any of its advantages. While in order to comply with the statute the inven-' tion has been described in language more or less specific as to structural features, it is to be understood that the invention is not limited to the specific features shown, but that the means and construction herein disclosed comprise but one of several-modes of putting the invention into effect, and the invention is therefore claimed in any of its forms or modifications within the legitimate and valid scope of the appended claims.

Having thus described our invention, we claim:

1. In the art of pulping and refining a coarse fibrous material, a method of, treating the fibrous material including the steps of cooking the material at an elevated temperature on the order of 212 and higher and at a pressure on the order of 150 p.s.i. and higher, transferring the cooked material under continued conditions of elevated temperature and pressure to a press, and in said press squeezing said material for extraction of cooking liquid and partly defibering said material.

2. In the art of pulping and refining a coarse fibrous material, a method of treating the fibrous material including the steps of cooking the material under conditions of temperature on the order of 212 and higher and at a pressure on the order of 150 p.s.i. and higher, transferring the heated material under continued conditions of elevated pressure to a press,-said material being squeezed in said press for extraction of cooking liquid and being partly defibered, and conducting the material from said press to a refiner for continued defibering.

3. In the art of pulping and refining, the combination of. a digester in which fibrous material is cooked under conditions ,of temperature and pressure elevated with respect to normal room temperature and pressure, a press having inlet and discharge ends, a connection from said digester to said press for conducting cooked fibrous material under continuing conditions of relatively elevated temperature and pressure from said digester to the inlet end of said press, screw means for advancing said material through said press to said discharge end, said fibrous material having residual cooking liquid expressed therefrom, and means cooperable with said screw means for defibering the material.

4. A combination according to claim 3, characterized by a refiner connected to the discharge end of said press and receiving the fibrous material emerging therefrom.

5. In the art of pulping and refining, a press providing a through passage for a fibrous material, means for moving the fibrous material through said passage, and means providing spaced apart low clearance areas in said passage for intermittent compression of the fibrous material. 7

6. In the art of pulping and refining, a screw press having a through chamber and screw means rotating in said chamber, characterized by longitudinally spaced. apart abutment means cooperating with said screw means to effect feed-squeeze cycles in the movement of the fibrous material through said press.

7. In the art of pulping and refining, a method of treating fibrous material including the steps of cooking the material, and immediately subjecting the material to movement through passages of low clearance whereby to add heat to the material and promote softening of the lignin for at least a partial defibering of the material as they pass through said low clearance passages, and at the same time compressing the fibrous material -for expression of cooking liquid therefrom.

8. In the art of pulping and refining, the combination of a digester in which fibrous material is cooked under conditions of temperature and pressure elevated with respect to normal room temperature and pressure, said digester having an unrestricted outlet, a press having inlet and outlet ends the former of which is in open communication with the outlet of said digester to receive the cooked material while maintaining such material under the conditions of elevated temperature and pressure, and screw means in said press feeding the material received at its inlet end to the outlet end thereof and intermittently applying squeezing pressures thereto.

9. A combination according to claim 8, characterized by a refiner in open communication with the outlet end of said press.

10. A combination according to claim 8, characterized in that said screw means comprises a rotary sleeve in said press formed with disconnected screw threads in alternating relation to relatively large diameter portions defining with the interior of the press low clearance areas through which the fibrous material is forced by said screw threads.

References Cited in the file of this patent UNITED STATES PATENTS 223,670 Farrell Jan. 20, 1880 1,505,934 Olier Aug. 19, 1924 1,915,812 Wollenberg June 27, 1933 1,954,012 Lemberger et al Apr. 10, 1934 2,018,938 Wells Oct. 29, 1935 2,089,992 Campbell et al. Aug. 17, 1937 2,287,332 Steely June 23, 1942 2,323,194 Beveridge et al. June 29, 1943 2,591,106 Sutherland Apr. 1, 1952 2,616,802 Kehoe et a1 Nov. 4, 1952 2,663,405 Messing Dec. 22, 1953 2,673,690 Segl Mar. 30, 1954

Claims (1)

1. IN THE ART OF PULPING AND REFINING A COARSE FIBROUS MATERIAL, A METHOD OF TREATING THE FIBROUS MATERIAL INCLUDING THE STEPS OF COOKING THE MATERIAL AT AN ELEVATED TEMPERATURE ON THE ORDER OF 212* AND HIGHER AND AT A PRESSURE ON THE ORDER OF 150 P.S.I. AND HIGHER, TRANSFERRING THE COOKED MATERIAL UNDER CONTINUED CONDIDTIONS OF ELEVATED TEMPERATURE AND PRESSURE TO A PRESS, AND IN SAID PRESS SQUEEZING SAID MATERIAL FOR EXTRACTION OF COOKING LIQUID AND PARTLY DEFIBERING SAID MATERIAL.

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