FIELD: textiles, paper.
SUBSTANCE: reactor vessel has an inlet to enter the cellulosic material and an outlet for discharging cellulosic material, and the cellulosic material flows through the reactor vessel from the inlet for the material to the outlet to unload the material; extracting sieve for hydrolysate and liquid; hydrolysis zone between the inlet for the material and extracting sieve for hydrolysate and liquid. Hydrolysis zone is maintained at a temperature of hydrolysis or above the temperature of hydrolysis at which the reaction of hydrolysis of the cellulosic material takes place. The reactor vessel contains the flush zone between the extracting sieve for hydrolysate and liquid and extracting sieve for flushing fluid, where hydrolysis is suppressed; an inlet pipe for flushing fluid to enter the flushing fluid in the flush zone. At least a part of flushing fluid flowing into the inlet pipe for flushing fluid flows through the flushing zone and is extracted with extracting sieve for hydrolysate and liquid, and the flushing fluid is entered into the flushing zone at a temperature below the temperature of hydrolysis. The reactor vessel contains a pulping area between the flushing zone and unloading zone for release of material, and the said pulping area includes a pipe for injecting of cooking liquor; and extracting sieve for cooking liquor in the pulping area or under the pulping area, and over the unloading release for the material, and the flushing fluid is a mixture of water and at least one of the substances, such as sodium hydroxide and white liquor, essentially free of sulfur.
EFFECT: reduction of risk of precipitation of lignin and other dissolved wood components, and reduction of consumption of alkali during the chemical pulping of cellulosic material.
40 cl, 1 dwg
