Method and system for efficient production of dissolving pulp in a kraft mill producing paper grade pulp with a continuous type digester

摘要

A method and system for pulp manufacturing used in connection with a kraft process includes a vertical pressure vessel operated in batch mode, a single-vessel or multi-vessel continuous digester, and other equipment for further processing brown stock, such as for washing, oxygen delignification, bleaching, and drying. A feeder and conveyance system may include a high pressure feeder or direct pump system, and selectively provides fiber-containing material to the continuous digester when making lower grade pulp product and to the vertical pressure vessel when making higher grade pulp such as dissolving pulp. The vertical pressure vessel is used for pre-hydrolysis and neutralization, after which the resulting pulp is fed to the continuous digester for cooking. White liquor and black liquor from the same mill may be used for the neutralization fluids. The same continuous digester is selectively used for cooking in connection with making pulp products of different grades or quality.

主权项

1. A method for selectively producing pulp of different grades using a continuous digester, comprising:
supplying organic fiber-containing material to a vertical pressure vessel system; performing pre-hydrolysis and neutralization in a batch mode on the organic fiber-containing material in the vertical pressure vessel system; providing the contents of the vertical pressure vessel system to a continuous digester after pre-hydrolysis and neutralization; and performing kraft cooking with the continuous digester to produce a brownstock for dissolving pulp; wherein either (1) the vertical pressure vessel system comprises a plurality of vessels for performing pre-hydrolysis and neutralization in a batch mode, and/or (2) the vertical pressure vessel system transfers organic fiber-containing material to a storage tank after pre-hydrolysis and neutralization to facilitate a steady flow thereof to the continuous digester.