Patent ID: 8647469

Claim:
A method for the impregnation and steaming of chips during the manufacture of chemical pulp, comprising; continuously feeding chips without preceding steam treatment to a top of an impregnation vessel, adding hot impregnation fluid (BL) at a first temperature above a boiling point of the hot impregnation fluid to the impregnation vessel, the hot impregnation fluid being added via a pipe having an outlet end located below a chip level (CH LEV ) established in the impregnation vessel and at a distance from a wall of the impregnation vessel such that steam is released into the chip volume for steaming the chips, the added hot impregnation fluid (BL) establishing a fluid level (LIQ LEV ) in the impregnation vessel being at least 1-2 meters below the chip level (CH LEV ), establishing a pressure at the top of the impregnation vessel that is essentially at atmospheric pressure, ±0.5 bar(g), withdrawing a first impregnation fluid (REC) for a first use from a first withdrawal volume located at about the fluid level (LIQ LEV ) behind a first screen row mounted in the wall of the impregnation vessel, withdrawing a second impregnation fluid from a second withdrawal volume located behind a second screen row located a distance below the first screen row and mounted in the wall of the impregnation vessel, the distance below the first screen row not exceeding a diameter of the impregnation vessel, returning at least a part of the second impregnation fluid via the pipe into a center of the impregnation vessel, and feeding out impregnated chips from a bottom of the impregnation vessel.