One embodiment provides an apparatus for cooking lignocellulosic material, comprising a pressurizable, inclined top separator including a sluicing liquor inlet for receiving a sluicing mixture comprising impregnated lignocellulosic material and sluicing liquor, a hot black liquor inlet, an excess liquor outlet, and an impregnated lignocellulosic material outlet; a continuous digester vessel including an impregnated lignocellulosic material inlet in communication with the impregnated lignocellulosic material outlet, and a warm black liquor outlet; and a black liquor circulation and heating loop including a warm black liquor inlet in communication with said warm black liquor outlet, a heater for heating warm black liquor to produce hot black liquor, and a hot black liquor outlet in communication with said hot black liquor inlet. Methods of making and using the apparatus are also provided.

One embodiment provides an apparatus for cooking lignocellulosic material, comprising a pressurizable, inclined top separator including a sluicing liquor inlet for receiving a sluicing mixture comprising impregnated lignocellulosic material and sluicing liquor, a hot black liquor inlet, an excess liquor outlet, and an impregnated lignocellulosic material outlet; a continuous digester vessel including an impregnated lignocellulosic material inlet in communication with the impregnated lignocellulosic material outlet, and a warm black liquor outlet; and a black liquor circulation and heating loop including a warm black liquor inlet in communication with said warm black liquor outlet, a heater for heating warm black liquor to produce hot black liquor, and a hot black liquor outlet in communication with said hot black liquor inlet. Methods of making and using the apparatus are also provided.

Digestion of cellulosic biomass solids may be complicated by release of lignin therefrom. Methods for digesting cellulosic biomass solids may comprise: heating cellulosic biomass solids and a digestion solvent in the presence of molecular hydrogen and a slurry catalyst capable of activating molecular hydrogen, thereby forming a phenolics liquid phase comprising lignin, an aqueous phase comprising an alcoholic component derived from the cellulosic biomass solids, and an optional light organics phase, the slurry catalyst being distributed in the cellulosic biomass solids and at least a portion of the slurry catalyst accumulating in the phenolics liquid phase as it forms; conveying at least a portion of the phenolics liquid phase and the slurry catalyst to a location above at least a portion of the cellulosic biomass solids; and after conveying the phenolics liquid phase and the slurry catalyst, releasing them such that they come in contact with the cellulosic biomass solids.

Digestion of cellulosic biomass solids may be complicated by release of lignin therefrom. Methods for digesting cellulosic biomass solids may comprise: heating cellulosic biomass solids and a digestion solvent in the presence of molecular hydrogen and a slurry catalyst capable of activating molecular hydrogen, thereby forming a phenolics liquid phase comprising lignin, an aqueous phase comprising an alcoholic component derived from the cellulosic biomass solids, and an optional light organics phase, the slurry catalyst being distributed in the cellulosic biomass solids and at least a portion of the slurry catalyst accumulating in the phenolics liquid phase as it forms; conveying at least a portion of the phenolics liquid phase and the slurry catalyst to a location above at least a portion of the cellulosic biomass solids; and after conveying the phenolics liquid phase and the slurry catalyst, releasing them such that they come in contact with the cellulosic biomass solids.

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.

The present invention relates to a method of producing steam at a digester plant of a chemical pulp mill. Black liquor is discharged from the digester at a first temperature and pressure. The black liquor is treated in a flash tank for generating flashed black liquor and flash steam at a second temperature and a second pressure, which are lower than the first temperature and pressure. The flashed black liquor is taken for further treatment to the evaporation plant. The flash steam is led to an indirect heat exchange contact with clean liquid in the reboiler for boiling the liquid and for generating steam. The steam is led from the reboiler into a fan or compressor for increasing the steam pressure to a third pressure, which is higher than the second pressure and for adjusting the pressure of the steam in the flash tank. Steam at a third pressure is used for pretreating comminuted cellulosic fiber material, such as chips, prior to cooking.

A method to treat fibrous materials for use in the formation of a biocomposite material that significantly reduces or eliminates the odors emitted from the fibrous materials is provided. In the method, the fibers or fibrous materials are initially treated to extract the raw fiber from the source plant material and the remove unwanted fractions of the fiber, such as the hemicellulose, lignin, and pectin, among others, leaving only the intact cellulose fibers. These cellulose fibers are then further processed in a second step to remove the odor from the cellulose fibers. The second step includes a combination of a second chemical treatment, dehumidification, and/or a cold plasma modification to render the cellulosic fibers odorless.