Continuous dissolving and blending apparatus for use in the manufacture of viscose

摘要

Apparatus for the continuous admixture of alkali cellulose xanthate with aqueous caustic soda solution in the manufacture of viscose comprises a disintegrator and mixer having an inlet or inlets for the xanthate and caustic soda solution and containing a number of screens of progressively decreasing mesh, agitating mechanism for forcing the xanthate in succession through the screens, and a grinding pump connected to the outlet of the disintegrator and mixer, the pump serving both to meter the flow of material through the apparatus and also to effect a further disintegration of the xanthate. A dissolving unit containing stirring mechanism for completing the solution of the xanthate in the caustic soda solution may be coupled to the outlet of the pump. As shown in Fig. 1 the xanthate is fed into the vessel 78 through the trunk 77, which may be directly coupled to the outlet of a churn such as is described in Specification 707,422. Caustic soda solution is fed into the vessel through a pipe 81 at a rate (controllable by a valve 82) appropriate to the rate of supply of xanthate from the churn. The xanthate receives a preliminary shredding in the uppermost compartment of the vessel 78 by the coaction of the paddle 86 mounted on the driven shaft 85 and the spikes 84 projecting upwards from the perforated plate 83. The paddle 86 has on its undersurface notches 87 which clear the spikes 84. The shredding and stirring action of the paddle 86 is assisted by the radial baffle 88. The slurry passes downwardly through the holes in the plate 83 into a mixing chamber bounded at the bottom by an imperforate plate 89 which has an upwardly and outwardly inclined flange 90 formed with holes of smaller diameter than those in the plate 83. Above the plate 89 is a centrifugal impeller 91 fixed to the shaft 85 which further reduces the size of the solids and forces the material through the flange 90. The mixture descends through a collecting chamber 92 to a second mixing chamber similar to the first and provided with a screen 90a having still smaller holes through which the material passes into a bottom mixing chamber 93 containing an impeller 94 having radial baffles 95 and 96 above and below it. The material leaves the vessel 78 through the outlet 97 and passes through the pipe 102 to the grinding pump 79, entering the latter through the inlet 103 (Fig. 2). The material then passes to the nip between the gear-wheels 98, 100 and thence to the interior of the fixed hollow outlet shaft 101 through fine radial holes 104 drilled through the roots of the teeth of the driven gear-wheel 100. The end of the hollow shaft 101 within the gear-wheel 100 is formed with longitudinal slots 105, and the edges of these slots coact with the radial holes 104 in the gear-wheel 100 to shear any solid matter extruded through the radial holes. The material leaving the pump 79 through the hollow shaft 101 is passed through a pipe 106 (Fig. 1) controlled by a valve 107 to the second stage mixer consisting of a series of interconnected U-tubes 80. Part of the material from the pump 79 may be recycled through the first stage mixer 78 through a pipe 108 controlled by a valve 109. The vertical limbs of the U-tubes 80 contain mechanically-driven stirrers 110 and the temperatures of the U-tubes are controlled by means of a tank or jackets containing a heat transfer liquid. Specifications 737,181 and 737,183 also are referred to.