Process for preparing cellulose solution and equipment therefor

A process for preparing a cellulose solution, comprising:

• (1) uniformly mixing cellulose pulp and N-methylmorpholine-N-oxide-aqueous solution with a temperature in a range from 70° C. to 100° C. to obtain a premix, wherein a mass of the N-methylmorpholine-N-oxide aqueous solution is 5 to 10 times that of the cellulose pulp, and the N-methylmorpholine-N-oxide aqueous solution has a water to N-methylmorpholine-N-oxide mass ratio in a range from 28:72 to 60:40;
• (2) subjecting the premix to dewatering by depressurized evaporation at a dewatering temperature in a range from 80° C. to 110° C. under a dewatering pressure in a nine from 4 kPa to 10 kPa to obtain a pre-swelling solution, wherein the pre-swelling solution has a water to N-methylmorpholine-N-oxide mass ratio in a range from 16:84 to 28:72;
• (3) subjecting the pre-swelling solution to heat preservation in a swelling kettle, the pre-swelling solution being sufficiently swelled in a temperature in a range from 55° C. to 95° C. for a residence time in a range from 3 min to 60 min to obtain a swelled solution inside the swelling kettle;
• and
• (4) subjecting the swelled solution to dewater by depressurized evaporation and dissolving to obtain the cellulose solution.