Process for continuous cellulose cooking

Abstract

Abstract The invention provides an apparatus and method for producing cellulosic pulp. A downwardly moving column of cellulosic material is contacted with a countercurrent flow of steam in a steaming zone. The steaming zone is maintained at an atmospheric pressure and temperature effective to expel air from the material without causing discoloration thereof. The temperature may be from 100* C. to 120* C. The steamed material is preimpregnated in a zone which is sealed from the ambient air. The preimpregnation is effected by contacting the steamed material with cold liquor having a temperature below that of the steamed material and effective to produce a rapid absorption of liquor therein. The cold liquor temperature is in the range of about 20* C. to about 80* C., and pressures of up to 10 gauge pressures can be employed. A condensate material resulting from the steaming treatment is separated from the cellulosic material after it has been subjected to the steaming treatment. The preimpregnated cellulosic material is sluiced through an impregnating zone containing hot cooking liquor at a temperature and superatmospheric pressure sufficient to effect impregnation thereof. The temperature within the impregnating zone may range from 100* C. to 180* C. and increase in the direction of material movement. The impregnated material is then passed from the impregnating zone for subsequent introduction into any desired pulp vapor phase digesting zone. The disclosed apparatus is used to effect the various process steps of the overall treatment.

Inventors

• 👤 Arne Johan Arthur Asplund
• 👤 Karl Nicolaus Cederquist
• 👤 Rolf Bertil Reinhall

Bibliographic Details