System and process for recovering heat from weak black liquor in a wood pulping process
AssigneeVeolia Water Solutions & Technologies North America, Inc.
InventorMichael S. Begley
Life of this patent
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Abstract
A wood pulping process includes producing weak black liquor and cooling the liquor as well as recovering heat therefrom by directing the weak black liquor through a spray film evaporator. A feed or condensate is directed into the spray film evaporator and the feed or condensate is sprayed onto the outer surfaces of a bundle of tubes. This results in the feed or the condensate being vaporized and producing a vapor that can be utilized as a heat source for other processes in a pulp mill.
Claims14
A method of cooling and recovering heat from weak black liquor produced in a pulp mill, comprising:
- digesting fibers in a digester to form weak black liquor;
- directing the weak black liquor through a series of tubes that form a part of a spray film evaporator;
- cooling and recovering heat from the weak black liquor passing through the spray film evaporator by:
- i. directing a feed to the spray film evaporator;
- ii. spraying the feed onto the tubes of the spray film evaporator and vaporizing the feed to produce a vapor;
- and
- iii. directing the vapor from the spray film evaporator and wherein the heat associated with the vapor can be utilized as a heat source for other processes in the pulp mill.
A method of treating weak black liquor produced in a pulp mill, comprising:
- digesting fibers in a digester to form weak black liquor;
- directing the weak black liquor through a series of tubes that form a part of a spray film evaporator;
- cooling the weak black liquor in the spray film evaporator;
- after cooling the weak black liquor, directing the weak black liquor to a multi-effect evaporation system and concentrating the weak black liquor therein to produce a concentrated black liquor and condensate;
- directing the concentrated black liquor to a recovery boiler;
- recovering heat from the weak black liquor by spraying condensate produced by the multi-effect evaporation system onto outside surfaces of the tubes and utilizing heat recovered from the weak black liquor to heat and vaporize the condensate which produces a vapor;
- and
- directing the vapor to the multi-effect evaporation system and utilizing the heat associated with the vapor to concentrate the weak black liquor in the multi-effect evaporation system.
Dependencies are inferred from the claim text.