摘要:
The latency of mechanical pulp is removed in a quick and simple manner. After refining of comminuted cellulosic material to produce mechanical pulp, the pulp is diluted (if necessary) to a consistency of between about 8-25%, and the pulp is then merely pumped to a further treatment stage. Pumping is effected utilizing a centrifugal pump which fluidizes the pulp, the fluidization imparting sufficient energy to the pulp to remove the latent properties. The pulp may be pumped to a storage stage prior to passage to a screening stage, and can be pumped in a direct (non-return) path from the pump to the screening stage. If desired or necessary, a portion of the pumped pulp can be recirculated and pumped again to ensure that sufficient energy is imparted thereto to effect latency removal.
摘要:
Biomass, such as bagasse, is pre-hydrolyzed, to ultimately effect hydrolysis of hemicellulose to sugars. Biomass is mixed with a mineral acid solution to form a slurry having a consistency of about 8 to 12% so that the acid solution properly wets the biomass. Then the slurry is dewatered to about 35 to 50% consistency, and is heated to reaction temperature (e. g. about 320.degree. F.) by direct contact with steam in the vapor phase of a vertical pressurized reactor, having a pressure of about 40 psig. A fluffer is preferably provided in the top of the reaction vessel. After a reaction time of about 30 minutes, the biomass is diluted and cold blown out of the bottom of the reactor. Pressate from the dewatering has acid added to it and is heated by indirect heat exchange with a sugar solution obtained by washing of the biomass discharged from the reactor, and is then mixed with the biomass as the acid solution.
摘要:
A mixer apparatus, and procedure, for mixing medium consistency (e.g., 6-15%) paper pulp, or like fibrous suspension, minimizes the power necessary to effect fluidization, and minimizes the speed for rotation of the rotor to effect fluidization. This is accomplished by preventing the formation of a shadow behind the rotor ribs as they rotate within the mixer housing, and similarly by preventing the formation of a shadow behind the stationary ribs formed on the housing (and cooperating with the rotating ribs). Such shadows are prevented by providing one wall of each of the ribs--the trailing wall in the direction of rotation of the rotor--so that it is sloped, and fills the volume the shadow would occupy.
摘要:
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.
摘要:
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.
摘要:
A drainer for a feed system for a cellulose digester has a substantially open and hollow inlet (devoid of a spiral flow imparter or a like flow restriction) and a substantially annular screen within an elongated housing having a flow direction between the housing inlet and outlet. The screen is slotted and the slots are at an angle &agr; between 5-90° with respect to the flow direction, so as to minimize passage of cellulose material through the slots, or clogging of the slots.
摘要:
In a cellulose pulp handling vessel having a first diameter material storing or treating portion above a second diameter discharge which is at least 20% less than the first diameter, reduced compression of the material and reduced power requirements of an agitator (if used), compared to prior art constructions are provided. A first transition, preferably a substantially smooth interior surface substantially frusto-conical transition, is provided between the first and second diameters. A second single-convergent transition may be provided above the first transition. A rotating agitator with at least two arms and associated paddles may be mounted for rotation in the transition about a substantially vertical axis for agitating the material in the transition. If desired, the transition may be moved, such as with a vibrator or oscillator. The invention is particularly suitable for pulp digesters and impregnation vessels.
摘要:
Low temperature steaming and slurrying of wood chips results in significant improvement in treatment, the chips being maintained at a temperature below 110.degree. C. (more desirably at about 105.degree. C. or less, and most desirably at about 100.degree. C. or less) until actually heated to cooking temperature. Steaming may be accomplished utilizing a vertical chip bin with one dimensional convergence and side relief or a horizontal steaming vessel, the steaming device connected to a high pressure feeder. A pump having an NPSHR less than the NPSHA may be used for drawing slurry into the high pressure feeder from the steaming device, or a pump may be disposed between the steaming device and the high pressure feeder for forcing slurry into the high pressure feeder through a conduit including a radiused elbow. The steaming is practiced at a pressure of 5 psig or less, preferably substantially atmospheric steaming is practiced. The pulp produced typically has strength properties at least about 10% greater than the pulp produced from material where it is steamed and slurried at temperatures in excess of 110.degree. C.
摘要:
Apparatus and a method allow shaft packings and bearing assemblies to be serviced for a shaft penetrating a pressurized vessel without requiring the vessel to be emptied.
摘要:
A system for feeding wood chips entrained in cooking liquor to a high pressure feeder connected to a continuous digester includes a vertical treatment (e.g. steaming) vessel, a metering device connected to the discharge from the steaming vessel, a generally vertical chip chute extending downwardly from the metering device, and a slurry pump having an inlet. The slurry pump pumps the slurry from an outlet thereof to a high pressure feeder low pressure inlet. In order to minimize the effect of changes in liquid volume upon the operation of the system, and to provide separate control of liquor volume and chip volume, a substantially vertical liquor tank having a top and bottom the bottom including a discharge opening above the slurry pump inlet is provided. A conduit directly connects the liquor tank discharge opening with the slurry pump inlet. A pressure isolating device may be used in the system if it is to operate at superatmospheric pressure rather than atmospheric pressure.