Process for preparing cellulose solution

摘要

In the present invention there is disclosed a process for preparing cellulose solution in tertiary amine-N-oxide. The process is characterized by preparation of a premix of the tertiary amine-N-oxide, water and cellulose and this premix is subsequently heated under pressure of 2.5 kPa to 10 kPa in a vertically fastened film-type evaporator having heated internal surface and a central shaft with blades being distributed along the shaft in such a manner that during rotation of the shaft the material in the evaporator is contacted by a plurality of the blades that are angularly distant about the shaft, whereupon water is evaporated from the premix in such an extent that the cellulose forms a solution in the amine oxide that is exhausted from the film-type evaporator at a temperature ranging from 90 degC to 135 degC, whereby the indicated process is further characterized in that when the area of the heated internal surface is within 1 me2 to 125 me2 then the circumferential distance of the adjacent blade tips is selected in the range of 65 mm to 175 mm and the blade circumferential velocity is adjusted within 2.5 m/s to 8 m/s so that the fall point of material falling down from the rotor blade lies by less than 90 degrees before the reception point of the rotor next blade.