US1982130A - Chemical treatment process for pulp manufacture - Google Patents

Description

NOV- 27, 1934- L. WOLLENBERG 1,982,130

CHEMICAL TREATMENT PROCESS FOR PULP MANUFACTURE Filed Sept. 5,l 1933 INVENTOR /fdr/"g/ .4. h/o//e/vrZ/g ATroRNExs Patented Nov. 27, 1934 UNITED STATES lPATENT OFFICE CHEMICAL TREATMENT PROCESS FOB PULP MANUFACTURE Harry L. Wollenberg, San Francisco, Calif., assignor to Longview Fibre Company, Longview, Wash., a corporation of Delaware Application September 5, 1933, Serial No. 688,103

3 Claims.

This invention relates generally to processes for effecting chemical treatment of various fibrous materials. It has particular application to treatment of material such as wood chips, with chemi- 5 cal liquor, in the manufacture of wood pulp.

The present invention may be considered to be a modiiication and improvement of the process disclosed in my Patent No. 1,918,812, granted June 27, 1933. The process and apparatus disclosed in l0 that patent is characterized by the fact that it makes possible a continuous treatment of iibrous material, like wood chips, with a-suitablechemical liquor. Brieiiy, the apparatus disclosed consists of an upright treatment chamber together with means for continuously introducing wood chips into the lower portion of the chamber against the pressure maintained therein. Within the upper portion of the chamber the fibrous material together with the liquor associated with the same is delivered over a wier, and is then expelled by means of a screw press which serves to discharge the fibrous material in the form of a compact column, and which removes the large part -of the accompanying liquid for separate delivery. While it is frequently desirable to separate a large part of the associated liquor from the treated brous material, expelling means such as disclosed in said patent must be designed in accordance with the character of the particular ibrous material being treated, if the iibrous material is to be properly expelled as a relatively compact column or plug which can withstand the relatively high pressure within the treatment chamber. Since the operation of such apparatus depends largely upon the frictional characteristics or" the ibrous material treated, it is apparent that such expelling means may not operate properly where the character of the fibrous material may change from time to time. For example with certain types of fibrous material the frictional characteristics may be such as to permit channeling, thus making it impossible to maintain the desired treatment chamber pressure. It is therefore an object of the present invention to provide an improved process of this character, which will make it possible to operate successfully upon a wide range of fibrous materials, both with respect to their untreated and treated conditions. It is a further object of the invention to make possible the production of an improved paper pulp in conjunction with processes and apparatus of the continuous treatment type. In this connection the invention ischaracterized by the subjecting of the fibrous material to a refining operation, while the ilbrous material is still being subjected to relatively high pressure and temperature and is in contact with the chemical liquor.

Further objects of the invention will appear from the following description in which the preferred embodiment of the invention has been set forth in detail in conjunction with the accompanying drawing.

The apparatus as illustrated in the drawing consists of a treatment chamber 10, which is preferably positioned upright, and which is relatively long compared to its cross sectional area. The means illustrated for continuously introducing brous material into the lower portion of this chamber is substantially identical to that disclosed in said Patent 1,915,812. Briey this mechanism consists of a rotatable feed screw 11, positioned within a housing 12. A cylindrical conduit 13 communicates between the discharge end of housing 12 and the bottom of the treatment chamber 10. Wood chips or other brous material to be treated are introduced into the housing '12 by way of hopper 14. The feed screw 11 is tapered and is shown provided with a gradually decreasing pitch, so that as the fibrous material is fed forwardly toward conduit 13, it is compressed to form a relatively compact column or plug. Such a relatively compact column of brous material is capable of serving as an effective closure against pressure within the treatment chamber.

'Ihe chemical treatmentliquor is preferably 85 introduced at the bottom of the treatment chamber 10, adjacent the region into which the fibrous material is introduced thru conduit 13. For this purpose l have indicated pipes 16 communicating with the bottom of the treatment chamber.

Where the apparatus is operated in such a manner that the brous material is digested or cooked by application of heat during its passage upwardly,of the treatment chamber, suitable heating means must be provided, as for example, a plurality of pipes 17 distributed along the lengthof the chamber, thru which steam can be introduced.

To minimize heat losses a jacket of insulating material 20 is shown. l

In order to break up the compact mass of brous material as it is introduced into the lower portion of chamber 10, and in order to cause the fibrous material to progress toward the upper end of the chamber, I have shown means in the form of a rotatable shaft 18, extending longitudinally of the chamber. Mounted at spaced points along this shaft are the inclined blades or flights 19. Certain of the blades 19 are grouped near the lower end of the shaft 18, to break up or mechanically disintegrate the compact column of iibrous material being introduced from conduit 13. In operation shaft 18 is slowly rotated in a direction to cause the nights to continually urge fibrous material upwardly.

The upper end of chamber 10 communicates with a goose-neck conduit 21, which forms a wier 22. A valve controlled vent pipe 25 is also provided, to afford a means for venting fixed gasesand fc` regulating the internal chamber pressure. The treated fibrous material together with the liquor associated with the same, flows over wier 22, and the removal of material from this point without relieving the pressure within the treatment chamber, utilizes apparatus constituting a departure from the apparatus disclosed in said Patent 1,915,812.

Arranged to receive all of the material flowing over wier 22, there is a device 23 which is commonly known in the pulp industry as a renner. The principal function for this device is to break up bundles of fibres, so that each fibre is suspended by itself in the liquor. Because of its action upon the fibre it can also be termed an attrition mill. While various forms of so-called refiners available on the market can be utilized,

, particular reference can be made to the Wiener and Jordan renners, which are somewhat similar to the device as illustrated. It may be preferable on some kinds of pulp to use.a hammer mill `or other disintegrating device instead of a refiner.

, Since renners are well known in the art, no detailed explanation need be made of the device 23 as illustrated in the drawing. Briefly it consists of a housing 24 having a truncated conical shaped portion, within which truncated conical rotor 26 is disposed. The inlet opening 2'7 to the housing .24 is in communication with the goose-neck 21, and after passage of the material between the r'otor 26 and the surrounding-inner walls of the housing 24, it is received within a delivery chamber 28. Rotor 26 is' mounted upon a shaft 29 which is adapted to be driven from a suitable source of power. Generally the outer periphery of the rotor 26, and the-associated inner walls of housing 24 are grooved, and theenlarged end of the rotor is provided with impelling vanes 31.

After passing thru the rener 23, the treated fibrous material together with the associated chemical'liquor is adapted to be received in two or more tanks 33 and 34. These tanks are shown connected to thedelivery end of the refiner 23, thru conduits 36 and 37, which are shown provided with valves 38 and 39. The lower ends of tanks 33 and 34 are shown provided with discharge conduits 4l and 42 which are likewise provided with valves 43 and 44. 'I'he upper portions of vboth the tanks 33 and 34 are also shown provided with valve controlled vent pipes 46 and v47 by means of which pressure Within the tanks -33 and 34 can be relieved. Additional pipes 48 andv 49 -are also provided in the event it is desired to introduce steam into the tanks` 33 and 34, for building up pressure prior to delivery into said tanks or for heating the contents thereof.

One particular manner of carrying out my process, with the apparatus described above, is as followsz--Assuming that the fibrous material to be treated is wood chips, the wood chips are supplied to hopper 14, and screw 1l rotated continuously, to cause these chips to be compressed together and forced thru the conduct 13 in the form of a compact column. The inner end of this compact column is continuously disintegrated or broken up by the action` of the lower flights 19 and noaiso j chamber, the fibrous material which has now progressed throughout the length of the chamber, is substantially completely cooked, and is associated with spent chemical liquor. This cooked or digested fibrous material together with the spent liquor discharges over wier 22, and then passes thru renner 23, Where bundles of fibre are disintegrated. After being received within the delivery pocket 28 of the reflner, the fibrous material together with its associated liquor is permitted to flow into one of the tanks 33 or 34,`say tank 33, thru conduit 36. -In this connection'it may be explained that while delivery into a tank is taking place, this tank is preferably maintained at a slightly lesser pressure than treatment chamber l0, in order to secure proper flow of the material. The development of too high a pressure in tank 33 can be obviated by occasional or continuous venting thru pipe 46. After tank 33 becomes filled, valve 38 is closed and valve 39 opened, to permit the discharge to take place into 'tank 34. The contents of tank 33 may now be drained to a point of final discharge, by first venting thru pipe 46 and then opening valve 43, or the contents may be forcibly blown out .by pressure.A After tank 34 has become filled, its contents are likewise delivered to a point of final discharge, and the fibrous material and spent liquor shunted thru conduit 36 to tank 33.

In the process and mode of operation described above, it is evident that while the fibrous material is being acted upon by the refiner 23, it is still being subjected to relatively high pressure and temperature and isincontact with the chemical liquor. Treatment under such conditions has a desirable effect upon the quality of the pulp,I and in addition facilitates subsequent Washing of the pulp. The use of this renner in the manner indicated is also particularly desirable when the treatment within chamber 10 secures a semi-cooking, which results in fibrous material in which cementing lignins which have beensoftened by cooking, without completely dissolving cementing lignins or entirely separating the fibres from each other.

The process as described above is susceptible of many modifications and. variations, dependent upon the type of fibrous material available, 'the type of pulp desired, and upon various operating conditions. For example rather than to use tanks 33 and 34 merely as receivers, the pulp While in these tanks can be subjected to washing, provided the tanks are sumcient in size and number, and have their lower portions provided with suitable drainage devices. viate somewhat from the procedure of substantially completely cooking the fibrous material before delivery to the renner 23. Thus if desired the temperatures within the treatment chamber 10, and the rate of progression of fibrous material therein, can be regulated so that the material received by tanks 33 and 34 is not completely cooked. Thereafter while within tanks 33 and 34, steam may be introduced if needed and cooking of the fibrous material can be permitted to proceed to completion. It is also possible to It is alsov possible to dei i Il modify the process in the manner 'described in my aforesaid Patent No. 1,918,312, to secure a pr'eand 34. In such event the brous material and chemical liquor traveling upwardly within 'the treatment chamber 10 is not heated to a temperature at which cooking becomes active. However the interior of the treatment chamber is maintained under a relatively 'high pressure above atmospheric, as by introducing air pressure thru the pipe line 25. After delivery of the disintegrated and preimpregnated material from the renner 23 (or some other attrition or disintegrating device such as a hammer mill) into the tanks 33 and 34, the material is heated to an elevated temperature to eifect cooking. For example assuming that a charge of such preimpregnated fibrous material together with its accompanying liquor has been received in tank 33, this material either with its accompanying liquor or after excess liquor has been drained therefrom (depending upon the character of liquor used and the results desired) can then be cooked by introducing steam thru pipe 48. After cooking the pulp can be drained or blown oi! thru conduit 41, to a point of final discharge.

ously introducing a treating liquor into the chamber, continuously advancing the mixture of fibrous material and treating liquor in a oompactmoving column upwardly thru the chamber, causing the liquor and treated brous material A to discharge .from the upper portion of the treating vessel over a wier, and then alternately delivering the material together with the liquor discharged over said wier into either one or the other of said vessels. y

2. In a process for the continuous treatment of brous material, characterized by the use of a relatively upright treatment chamber together with at least two receiving vessels, said method comprising continuously introducing the tlbrous material into the treatment chambensimultaneously introducing a treating liquor into the chamber; continuously advancing the mixture of iibrous material and treating liquor in a composite moving column upwardly through the chamber, causing the liquor and treated fibrous material to discharge from the upper portion of the treating chamber over a wier, alternately delivering the material together with the liquor discharged over said wier into either one or the other of said vessels, and then subjecting the material to washing while within said vessels.

3. In a process for the continuous treatment of fibrous material, characterized by the use of a relatively upright treatment chamber together with at least two receiving vessels, said method comprising continuously introducing the brous material into the treatment chamber, simultaneously introducing a treating liquor into the chamber, continuously advancing the mixture of brous. material and treating liquor in a composite moving column upwardly through the chamber, the interior of the chamber being maintained at a pressure substantially greater than atmospheric, causing theliquor and treated brous material to discharge from the upper portion of the treatment chamber over a wier, and alternately delivering the material together with the liquor discharged over said wier into either one or the other of said vessels, a vessel receiving the material and liquid being likewise maintained at a pressure greater than atmospheric.

HARRY L. WOILENBERG..

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