Abstract: A method and system for preventing exclusions in an air quality control system (AQCS) of a type having a scrubber, either a circulating fluidized bed (CFB), transport reactor (TR) or spray-dryer absorber SDA, and in all three cases with a flue gas recirculation FGR system. The invention automatically pre-heats flue gas recirculated to the input of the CFB/TR/SDA scrubber during periods of low temperature operation. The system supplements the “traditional” gas recirculation scheme with heater(s) that are used during periods of low temperature. During periods of low load conditions, the system monitors the SDA/TR/CFB inlet temperature and, when it falls below a setpoint, the control system increases the heat input of the pre-heater(s) in the FGR system in order to maintain a minimum inlet temperature.

Abstract: A reactor vessel including: a mixing chamber having a vertical length, an upper inlet, and a lower outlet; and a vertically oriented paddle within the mixing chamber and having a cross-sectional shape of a hydrofoil, wherein the paddle moves with respect to the mixing chamber.

Abstract: A prehydrolysis of wood chips or other lignocellulosic material in a vessel having a gaseous portion and a liquid portion. The vessel includes at least one stress relieving piece that inhibits overcompression of the lignocellulosic material. The vessel operates in a continuous process. A slurry of lignocellulosic material and liquid is removed from the bottom of the vessel.

Abstract: This disclosure relates to a method for treating a biomass comprising a lignocellulosic material to produce fermentable sugars comprising the steps of treating the biomass to produce a biomass with a depolymerized lignin, adding a carbonyl scavenger to the biomass before, during, or after said treating step to inhibit repolymerization of the lignin, adding at least one of a laccase enzyme and a cellulases enzyme to the biomass with depolymerized lignin subsequently to the addition of the carbonyl scavenger, and producing a fermentable sugar from the action of the laccase enzyme and cellulases enzyme on the biomass with depolymerized lignin.

Abstract: Systems are provided for continuously producing chemical cellulose pulp from a slurry of comminuted hardwood material by subjecting the slurry of comminuted hardwood material to a first cooking stage under conditions sufficient to reduce syringyl lignin (s-lignin) content in the hardwood material as compared to guaiacyl lignin (g-lignin) content therein, and thereafter subjecting the slurry of comminuted hardwood material to a second cooking stage under conditions sufficient to reduce the g-lignin content remaining therein after the first cooking stage.

Abstract: A method for feeding a cellulosic fibrous material to a high pressure processing vessel including: pressurizing a low pressure flow of the fibrous material in a high pressure transfer device; discharging a high pressure flow of the fibrous material from the transfer device to a conduit in fluid communication with the processing vessel; discharging a low pressure flow of fluid and fibrous material from the transfer device; downstream of the transfer device, pressurizing the discharged low pressure flow; merging the pressurized low pressure discharge flow with the discharged high pressure flow, and transferring the merged flow to the processing vessel.

Abstract: A chip pretreatment process which comprises conveying the feed material through a compression screw device having an atmosphere of saturated steam at a pressure above about 5 psig, decompressing and discharging the compressed material from the screw device into a decompression region, feeding the decompressed material from the decompression region into a fiberizing device, such as a low intensity disc refiner, where at least about 30 percent of the fiber bundles and fibers are axially separated, without substantial fibrillation of the fibers. In a more specific form the invention is directed to a process for producing mechanical pulp, including the steps of fiberizing wood chip feed material in a low intensity disc refiner until at least about 30 percent of the fibers are axially separated with less than about 5 percent fibrillation, and subsequently refining the fiberized material in a high intensity disc refiner until at least about 90 percent of the fibers are fibrillated.

Abstract: A method for adding cooking liquor into a vapor phase continuous digester for producing chemical cellulose pulp from cellulose chips including: introducing a slurry of the cellulose chips from a feed system to an inverted top separator in a top vapor phase section of the digester; distributing the slurry of the cellulose chips from the top separator into the vapor phase section of the digester; passing liquor through a conduit included with the drive shaft assembly of the top separator, and introducing the liquor from the conduit into the slurry as the slurry flows through the top separator or is distributed from the separator into the vapor phase section.

Abstract: A system and method for feeding comminuted cellulosic fibrous material such as wood chips to the top of a treatment vessel such as a continuous digester provide enhanced simplicity, operability, and maintainability by eliminating the high pressure transfer device conventionally used in the prior art. Instead of a high pressure transfer device the steamed and slurried chips are pressurized using a single vane slurry pump in series with a centrifugal slurry pump both of which are located at least thirty feet below the top of the treatment vessel and for pressurizing the slurry to a pressure of at least about 10 bar gauge.

Abstract: A top separator assembly for a digester is disclosed comprising: a rotatable shaft for the top separator; a packing for the shaft; and a sealing ring operatively mounted to the shaft and having a nominal clearance with the pack box, said sealing ring mounted so that up lifting of said shaft provides a substantially fluid tight seal between said pack box and a side of said ring (in the digester) opposite the pack box.

Abstract: A system and method for feeding comminuted cellulosic fibrous material such as wood chips to the top of a treatment vessel such as a continuous digester provide enhanced simplicity, operability, and maintainability by eliminating the high pressure transfer device conventionally used in the prior art. Instead of a high pressure transfer device the steamed and slurried chips are pressurized using a single vane slurry pump in series with a centrifugal slurry pump both of which are located at least thirty feet below the top of the treatment vessel and for pressurizing the slurry to a pressure of at least about 10 bar gauge.

Abstract: A high pressure transfer device has a rotor mounted in a housing for rotation with respect to inlet and outlet ports and having through going pockets. The pockets have interior surface configurations substantially devoid of nooks, crannies, and related flow restrictions. This can be accomplished by providing inserts in the pockets, or by constructing the pockets so that there are substantially smooth interior wall tubes extending from one end of the rotor and the other and cooperating with an inlet and an outlet at the same time. Using the high pressure transfer device to feed wood chips or the like in a slurry using a high pressure transfer pump can result in flow through the rotor pockets that is more uniform by at least 5% compared to in conventional high pressure transfer devices.

Abstract: A high pressure transfer device has a rotor mounted in a housing for rotation with respect to inlet and outlet ports and having through going pockets. The pockets have interior surface configurations substantially devoid of nooks, crannies, and related flow restrictions. This can be accomplished by providing inserts in the pockets, or by constructing the pockets so that there are substantially smooth interior wall tubes extending from one end of the rotor and the other and cooperating with an inlet and an outlet at the same time. Using the high pressure transfer device to feed wood chips or the like in a slurry using a high pressure transfer pump can result in flow through the rotor pockets that is more uniform by at least 5% compared to in conventional high pressure transfer devices.

Abstract: In the feeding of a slurry of comminuted cellulosic fibrous material to a digester (continuous or batch) in the production of chemical pulp, one of the tanks used in the feed system (which preferably includes a high pressure feeder) may be eliminated without consequent loss of its function by providing a single tank with the combined functions of controlling the level of liquid in a slurrying conduit which supplies slurry to a slurry pump, and storing and substantially continuously supplying liquid to a make-up liquid pump connected to the digester. The single tank preferably surrounds the slurrying conduit and is substantially concentric, and in liquid communication, with it. A gap of 3-48 inches may be provided between the bottom of the conduit and a connection to the slurry pump. A screen or strainer may be provided in the gap, which is substantially surrounded by the tank.

Abstract: In the feeding of a slurry of comminuted cellulosic fibrous material to a digester (continuous or batch) in the production of chemical pulp, one of the tanks used in the feed system (which preferably includes a high pressure feeder) may be eliminated without consequent loss of its function by providing a single tank with the combined functions of controlling the level of liquid in a slurrying conduit which supplies slurry to a slurry pump, and storing and substantially continuously supplying liquid to a make-up liquid pump connected to the digester. The single tank preferably surrounds the slurrying conduit and is substantially concentric, and in liquid communication, with it. A gap of 3-48 inches may be provided between the bottom of the conduit and a connection to the slurry pump. A screen or strainer may be provided in the gap, which is substantially surrounded by the tank.

Abstract: A top separator assembly for a digester is disclosed comprising: a rotatable shaft for the top separator; a packing for the shaft; and a sealing ring operatively mounted to the shaft and having a nominal clearance with the pack box, said sealing ring mounted so that up lifting of said shaft provides a substantially fluid tight seal between said pack box and a side of said ring (in the digester) opposite the pack box.

Abstract: By the utilization of a jet ejector (such as a thermocompresser) in a cellulose chemical pulp mill, it is possible to effectively increase the utilization of steam. The volume of steam from a flash tank which flashes black liquor from a pulp digester may be increased (e.g. at least about 10%), while the volume and temperature of the liquor discharged from the flash tank are decreased and its concentration increased, by operatively connecting the jet ejector to the steam discharge from a flash tank. The jet ejector is supplied with higher pressure steam from another source which can result in a low pressure or partial vacuum condition in the flash tank. The flash tank may be a single flash tank or one of a series of flash tanks, and an ejector can be associated with at least another flash tank in the series.

Abstract: A high pressure transfer device has a rotor mounted in a housing for rotation with respect to inlet and outlet ports and having through going pockets. The pockets have interior surface configurations substantially devoid of nooks, crannies, and related flow restrictions. This can be accomplished by providing inserts in the pockets, or by constructing the pockets so that there are substantially smooth interior wall tubes extending from one end of the rotor and the other and cooperating with an inlet and an outlet at the same time. Using the high pressure transfer device to feed wood chips or the like in a slurry using a high pressure transfer pump can result in flow through the rotor pockets that is more uniform by at least 5% compared to in conventional high pressure transfer devices.

Abstract: A high pressure transfer device has a rotor mounted in a housing for rotation with respect to inlet and outlet ports and having through going pockets. The pockets have interior surface configurations substantially devoid of nooks, crannies, and related flow restrictions. This can be accomplished by providing inserts in the pockets, or by constructing the pockets so that there are substantially smooth interior wall tubes extending from one end of the rotor and the other and cooperating with an inlet and an outlet at the same time. Using the high pressure transfer device to feed wood chips or the like in a slurry using a high pressure transfer pump can result in flow through the rotor pockets that is more uniform by at least 5% compared to in conventional high pressure transfer devices.

Abstract: A comminuted cellulosic fibrous material treatment vessel assembly includes a substantially vertical vessel having a top, bottom, and outlet, and through which the material flows in a flow direction. The vessel preferably has a substantially cylindrical wall with at least one diameter-changing transition between the inlet and the outlet. A screen assembly is preferably provided at or just past the transition. The screen assembly comprises one or more annular screen surfaces diverging in the flow direction of the material, the angle of divergence being between about 0.5-10° to the vertical, and preferably substantially continuous. Providing such a screen assembly reduces the radial compression of material thereon, and increases the volume and rate of liquid that can flow through the material and be removed through the screen surface compared to a non-diverging screen surface (that is a right-cylindrical surface).