| 摘要 |
PROBLEM TO BE SOLVED: To reduce the undissolved fiber content of a cellulose ether water solution, enhance productivity and obtain cellulose ether stably by grinding pulp by using a vertical roller mill so as to produce powder pulp. SOLUTION: A raw material pulp is powdered by using a vertical roller mill 10. The raw material pulp is charged into a container 1 through a raw material supply opening 11 and made to fall onto a turntable 2, and then is accumulated in a groove 4 by centrifugal force and compressed and ground by a roller 5 for powdering. At this time a whirling and ascending air current is generated by air from an air supply port 20 so as to ascend pulp powder to an upper part of an interior of the container 1. Only sufficiently ground powder pulp is introduced into a slit of a separator 7 and classified and then discharged outside of the container 1 from a product outlet 15 and collected by a bag filter. On the other hand, the powder pulp thus obtained is used as a raw material to produce cellulose ether. |
