Method in connection with the pretreatment of comminuted fibrous material
AssigneeKaverner Pulping AB
InventorsVidar Snekkenes, Lennart Gustavsson
Life of this patent
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Abstract
A method in connection with the pretreatment of comminuted fibrous material intended for chemical cellulose pulp production. The fibrous material is fed through a low pressure system that has a gas phase part followed by a liquid phase part. The liquid phase part includes a low pressure circulation where a circulating liquid is withdrawn from the fibrous material and recirculated back to the fibrous material in an upstream position. The fibrous material is sluiced into a high pressure system that has a liquid phase transfer part operatively connected to a digester. A hot process liquid and/or the circulating liquid are evaporatively cooled by being allowed to flash within the low pressure system.
Claims16
A method in connection with the pretreatment of comminuted fibrous material for chemical cellulose pulp production, comprising:
- (a) feeding the comminuted fibrous material through a low pressure system, the low pressure system comprising a gas phase portion followed by a liquid phase portion, the liquid phase portion having a low pressure circulation, the low pressure circulation comprising a level tank;
- (b) withdrawing a circulating liquid from the fibrous material flowing at a withdrawal point in the low pressure circulation;
- (c) recirculating the circulating liquid back to the fibrous material at a recirculating point that is upstream of the withdrawal point;
- (d) balancing a pressure in the level tank against a pressure in the gas phase portion of the low pressure system to control a liquor level between the gas phase portion and the liquid phase portion;
- (e) stabilizing a liquid flow from the low pressure circulation;
- (f) sluicing the fibrous material into a high pressure system of a digester comprising a liquid phase transfer portion being operatively connected to a digester;
- (g) providing a hot process liquid having a pressure that is the same as a pressure of the high pressure system, the pressure of the high pressure system being greater than a pressure of the low pressure system;
- (h) leading the hot process liquid from the high pressure system directly into the level tank above a tank liquor level;
- and
- (i) evaporatively cooling the hot process liquid from the high pressure system by allowing the hot process liquid to flash above the tank liquor level inside the level tank.
Dependencies are inferred from the claim text.