Patent ID: 8801898

Claim:
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 R 1 in the treatment vessel, the radius R 1 being smaller than a radius R 2 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.