Patent GB-372425-A (GB)
Title: Improvements in and relating to the manufacture of cellulose and the like
IPC: D21C3/24
Filed: 1931-02-14
Abstract: 372,425. Manufacture of cellulose pulp. TRIGGS, W. W., 57, Lincoln's Inn Fields, London.-(Lemberger, L. ; 27, Doudleveckß, PIzen, Czecho-Slovakia.) Feb. 14, 1931, No. 4772. [Class 96.] In the preparation of cellulose pulp, the raw material which is being digested passes continuously through a battery consisting of a number of digesters arranged in series without any mechanical conveying means being used. Automatic means may be provided for controlling the supply of raw material and treating liquors, and automatic means may also be provided for removing the finished pulp. The raw material is blown from the storage hopper 110 by a blower 111 into the top of the first digester 1. The material is consolidated into a plug by the electrically operated beater 13 in the conical neck 14, thus sealing the digester from the atmosphere. If too much raw material is fed in, the beater 13 is gradually raised until contact 1151 disconnects the circuit to the blower 111. Liquor is introduced at 124 and its height in the digester maintained constant by a regulating valve 123 actuated by a float 121. The material slowly passes to the bottom of the preliminary digester 1, through the connecting arm 21-27 containing sieves 24, 25 for removing spent liquor, to the main digester 2, thence to the quiescent digester 3 and final digester 4, up the neck 4z to the overflow device 46 operated by the float 44 so as to maintain a constant head. The height of the columns 1z, 4z causes a pressure of several atmospheres to be maintained in the digesters. Separating sieves 15, 47 at each end of the apparatus are connected to an injector 60, whereby the surplus gas and steam mixture is passed into water, and the SO2 absorbed. The gas liquor so obtained is introduced through sieves into various parts of the apparatus. Spent liquors collected in the tank 48 are raised to the recovery plants 49. Steam is introduced directly into the digesters through perforated pipes 61 .. 64, or superheated steam is introduced at 77, 78, 79, the inlets being disposed so as to promote turbulence. The risers 61 .. 64 may also be used for the introduction, by means of injectors 51 .. 54, of gas and steam mixtures recovered from a subsequent stage, similarly the injector 58 passes gas &c. from the top of the main digester 2 into the neck 1z of the preliminary digester. One or more rotary improving digesters 130 may be connected to the final digester at 30, 67, or 68 for further treating the pulp, for digesting samples &c. Steam and gas may be supplied through pipes 69, 128, and manholes 131, 133 provide access to the contents. In an alternative form of feeding apparatus, Fig. 2, the stamper 13 is replaced by a sliding propeller 13<11> driven by worm gearing 116<1>, 116<11>. If the supply of material becomes too great, the propeller rises and by means of a rack 115<11> rotates the rheostat 119 controlling the electric motor which supplies the raw material, either by blowing or by means of a conveyer worm 1181. The number of digesters may be increased, and each may consist of one or more superimposed vessels as 1a, 1b, Fig. 2.