Wood pulping process including pulping wood to produce a pulping effluent or liquor. Pre-concentrating the liquor in a pre-concentration unit produces concentrated liquor, a contaminated condensate and a non-contaminated condensate. Directing the concentrated liquor to a multi-effect train of forced circulation solids concentrators that further concentrating the concentrated liquor to form a highly concentrated liquor. Directing the contaminated condensate produced by the pre-concentration unit to a steam stripper and stripping gases therefrom and in the process producing a contaminated vapor stream. Utilizing the contaminated vapor stream and its thermal energy to power the forced circulation solids concentrators of the multi-effect train.

Wood pulping process including pulping wood to produce a pulping effluent or liquor. Pre-concentrating the liquor in a pre-concentration unit produces concentrated liquor, a contaminated condensate and a non-contaminated condensate. Directing the concentrated liquor to a multi-effect train of forced circulation solids concentrators that further concentrating the concentrated liquor to form a highly concentrated liquor. Directing the contaminated condensate produced by the pre-concentration unit to a steam stripper and stripping gases therefrom and in the process producing a contaminated vapor stream. Utilizing the contaminated vapor stream and its thermal energy to power the forced circulation solids concentrators of the multi-effect train.

The invention discloses a method of continuous cooking cellulose fibrous material in a digester, said digester having a top and a bottom. The method of the invention comprises the steps of:feeding a slurry comprising cellulosic fibrous material and cooking liquor into the top the digester,feeding a first washing liquor into the bottom portion of the digester, which first washing liquor moves counter currently up through at least part of the digester,removing pulp from the bottom of the digester,feeding a second washing liquor into the center of the digester at least at the level of a first screen section,feeding a third washing liquor into the center of the digester at the level of a second screen section, andwithdrawing the cooking liquor and the washing liquors from the first screen section and from the second screen section, which first screen section is arranged in a lower part of the digester and which second screen section is arranged below said first screen section. Thus, in accordance with the invention, a third washing liquor is added to the center of digester at the level of an additional, second extraction screen section arranged in the lower part of the digester. The method makes it possible to increase the production rate in the digester but still maintain or even increase the washing efficiency.

The invention discloses a method of continuous cooking cellulose fibrous material in a digester, said digester having a top and a bottom. The method of the invention comprises the steps of:feeding a slurry comprising cellulosic fibrous material and cooking liquor into the top the digester,feeding a first washing liquor into the bottom portion of the digester, which first washing liquor moves counter currently up through at least part of the digester,removing pulp from the bottom of the digester,feeding a second washing liquor into the center of the digester at least at the level of a first screen section,feeding a third washing liquor into the center of the digester at the level of a second screen section, andwithdrawing the cooking liquor and the washing liquors from the first screen section and from the second screen section, which first screen section is arranged in a lower part of the digester and which second screen section is arranged below said first screen section. Thus, in accordance with the invention, a third washing liquor is added to the center of digester at the level of an additional, second extraction screen section arranged in the lower part of the digester. The method makes it possible to increase the production rate in the digester but still maintain or even increase the washing efficiency.

A method for manufacturing bleached pulp from a feedstock that includes recycled paper. The method includes steps of: (1) impregnating the feedstock with cooking liquor to yield an impregnated material having a liquor-to-fiber mass ratio of at most about 4:1; (2) cooking the impregnated material to remove at least a portion of the lignin within the impregnated material, thereby yielding a cooked pulp; and (3) bleaching the cooked pulp.

A method for manufacturing bleached pulp from a feedstock that includes recycled paper. The method includes steps of: (1) impregnating the feedstock with cooking liquor to yield an impregnated material having a liquor-to-fiber mass ratio of at most about 4:1; (2) cooking the impregnated material to remove at least a portion of the lignin within the impregnated material, thereby yielding a cooked pulp; and (3) bleaching the cooked pulp.

Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, that adjust a high-pressure feeder of a feed system used in pulp production based on the fluid leakage through a low-pressure outlet of a high-pressure feeder. Methods can include obtaining multiple flow values, including (1) a make-up liquor flow value, (2) a black liquor flow value, (3) a white liquor flow value, (4) a chip chute circulation flow value, and (5) a high pressure feeder purge flow value. Methods can include determining a chip flow value specifying a flow of chips provided to the high-pressure feeder. Based on the flow values, methods can determine a fluid leakage value specifying an amount of fluid leakage through a gap between a pocket rotor and the housing of the high pressure feeder. Methods can adjust an annular gap based on the fluid leakage value satisfies a threshold leakage value.

Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, that adjust a high-pressure feeder of a feed system used in pulp production based on the fluid leakage through a low-pressure outlet of a high-pressure feeder. Methods can include obtaining multiple flow values, including (1) a make-up liquor flow value, (2) a black liquor flow value, (3) a white liquor flow value, (4) a chip chute circulation flow value, and (5) a high pressure feeder purge flow value. Methods can include determining a chip flow value specifying a flow of chips provided to the high-pressure feeder. Based on the flow values, methods can determine a fluid leakage value specifying an amount of fluid leakage through a gap between a pocket rotor and the housing of the high pressure feeder. Methods can adjust an annular gap based on the fluid leakage value satisfies a threshold leakage value.

The present disclosure generally relates to a pretreatment arrangement (100) for pretreatment of lignocellulosic biomass comprising a reactor vessel (101) having an upstream inlet (102) for receiving biomass and a downstream outlet (103) for discharging biomass. The pretreatment arrangement (100) further comprises a gas valve (104) and gas flow control means (106).

The present disclosure generally relates to a pretreatment arrangement (100) for pretreatment of lignocellulosic biomass comprising a reactor vessel (101) having an upstream inlet (102) for receiving biomass and a downstream outlet (103) for discharging biomass. The pretreatment arrangement (100) further comprises a gas valve (104) and gas flow control means (106).