Process for upgrading low-quality wood
AssigneeShell Oil Company
InventorsHerman P. Ruyter, Anton Hortulanus
Life of this patent
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Abstract
A process for upgrading low-quality wood including a softening stage, wherein one or more sections of low-quality wood are heated, in the presence of an aqueous medium and at a pressure which is at least the equilibrium pressure of the medium at the operating temperature, to a temperature in the range of from about 120.degree. C. to about 160.degree. C. and maintaining the temperature until the temperature difference between the center and the outer parts of the sections is less than about 20.degree. C., a dewatering stage and a curing stage.
Claims19
A process for upgrading low-quality wood to high-quality wood comprising:
- a) a softening stage, wherein one or more sections of low quality wood are heated in the presence of an aqueous medium and at a pressure which is at least the equilibrium pressure of said medium at the operating temperature, to a first temperature in the range of from about 120.degree. C. to about 160.degree. C. and maintaining said temperature until the temperature difference between the center and the outer parts of the sections is less than about 20.degree. C. and then heating to a second temperature in the range of from about 160.degree. C. to about 240.degree. C. for not more than one hour until the temperature difference between the center and the outer parts of the sections is less than about 20.degree. C., b) a dewatering stage, and c) a curing stage.
Dependencies are inferred from the claim text.