PURPOSE: To efficiently digest pulp chips by replacing air with steam in a steaming vessel installed on the way for supplying chips to a digester while transferring the chips to the digester and increasing or decreasing the amount fed of alkaline solution depending on a driving load fluctuation to stabilize the quality of a product.
CONSTITUTION: In a digesting process of pulp chips, wood chips T of a raw material and an alkaline digesting solution A are continuously fed to the top of a digester 1 through a chip feeding duct 2 and they (T and A) are heated in the digester 1 to dissolve lignin in the wood chips to obtain unbleached pulp. In a steam vessel 3 installed in the chip feeding duct 2, the air in the raw material is replaced with an introduced steam S while the wood chips T is transferred by a spiral screw continuously driven by the rotation of screw axis 4. On the same time, a load fluctuation of a motor 5 driving the screw axis 4 is determined and the opening of a flow regulating valve 12 is controlled depending on the load fluctuation by a controller 11 to increase or decrease the amount of the alkaline solution A fed to the digester 1. Thus, the chips for pulp is digested to obtain a product having a stable quality.
YANO KENICHIRO
NAGAO MASAICHI
NOGUCHI YOSHIO
