Method and arrangement for adding treatment liquors to cellulose raw material in a continuous process using down flow vessels
AssigneeValmet Corporation
InventorsDaniel Trolin, Fredrik Wilgotson, Peter Henricsson
Life of this patent
Estimating the term…
Abstract
The method and arrangement is for adding treatment liquor to comminuted cellulose material, preferably wood chips, during the manufacture of chemical pulp in a continuous process. The process uses a down-flow vessel where chips are descending down the vessel in a plug-flow and where treated chips are continuously fed out at the bottom of the vessel. By arranging more than two parallel pipes offset from the center of the vessel a better distribution of treatment liquor is obtained. Any disturbance of the chip plug flow descending down the vessel is reduced to a minimum.
Claims2
A method for adding a hot treatment liquor and steam to un-steamed comminuted cellulose material during a manufacture of chemical pulp in a continuous process, comprising:
- providing a down-flow continuous treatment vessel having at least two vertical pipes being arranged parallel to a direction of a plug-flow of chips continuously descending down the vessel, the vertical pipes having open lower ends disposed below a chip level (CH_LEV) of the chips of a chip volume inside the treatment vessel,
- adding the treatment liquor via the at least two vertical pipes, the treatment liquor having a temperature exceeding a boiling temperature at a prevailing pressure at the outlets so that a flashing effect is obtained in the chip volume located above a liquid level (LIQ_LEV) established in the treatment vessel below the chip level (CH_LEV),
- distributing the treatment liquor in parallel flows and flashed steam at multiple points over a plug flow area with the at least two vertical pipes located at a radial position of a radius R1 in the treatment vessel, the radius R1 being smaller than a radius R2 of the treatment vessel at a height of the open lower ends of the two vertical pipes,
- reducing interference of the plug-flow to a minimum by distributing the treatment liquor via the at least two vertical pipes,
- locating the outlets of the open lower ends above the liquid level (LIQ_LEV) but below the level (CH_LEV) of the chips in the treatment vessel, and
- continuously feeding out treated chips at a bottom of the treatment vessel.
Dependencies are inferred from the claim text.