Apparatus for pulping sawdust
First Claim
1. A system for producing chemical pulp from sawdust, comprising:
- a static down-flow superatmospheric pressure retention vessel having a top for receipt of a sawdust slurry, and a bottom which includes non-mechanical discharge means for discharging chemical pulp;
a first mixer means for mixing steam and cooking liquor with sawdust to form an initial slurry, subsequent means for diluting, raising the temperature to cooking temperature, and pressurizing the initial slurry to provide a slurry suitable for cooking, and elevating the slurry to the top of said retention vessel to feed slurry Into the top of the retention vessel; and
a superatmospheric pressure vessel connected to said non-mechanical discharge means and including means for displacing cooking liquid from the pulp after the pulp is discharged from the bottom of said retention vessel to lower the temperature thereof below cooking temperature.
1 Assignment
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Accused Products
Abstract
Chemical cellulose pulp is made from sawdust utilizing a static down-flow retention vessel. By adding steam and cooking liquor to a flow of sawdust a heated slurry, at a cooking temperature of about 250-350° F., is produced. The heated slurry is, at superatmospheric pressure, moved downwardly in the static down-flow retention vessel while cooking temperature is maintained, for a time period of about 0.5-6 (preferably 1 to 3) hours, the slurry having a consistency of about 5-30%. At superatmospheric pressure, without significant reduction in pressure from the retention vessel, the slurry is cooled to well below cooking temperature by diffusing cooling liquid through it, as in a conventional pressure diffuser. The discharge from the retention vessel is preferably substantially solely gravity action (e.g. using a discharge with single convergence and side relief). Various mixing, diluting, thickening, steaming, and pumping devices are utilized in the system from initial steaming of the sawdust to passage into the top of the retention vessel.
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Citations
10 Claims
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1. A system for producing chemical pulp from sawdust, comprising:
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a static down-flow superatmospheric pressure retention vessel having a top for receipt of a sawdust slurry, and a bottom which includes non-mechanical discharge means for discharging chemical pulp;
a first mixer means for mixing steam and cooking liquor with sawdust to form an initial slurry, subsequent means for diluting, raising the temperature to cooking temperature, and pressurizing the initial slurry to provide a slurry suitable for cooking, and elevating the slurry to the top of said retention vessel to feed slurry Into the top of the retention vessel; and
a superatmospheric pressure vessel connected to said non-mechanical discharge means and including means for displacing cooking liquid from the pulp after the pulp is discharged from the bottom of said retention vessel to lower the temperature thereof below cooking temperature. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification