Patent ID: 6113739
Filing Date: 2000-09-05
Classification: D21C,Y02P

Abstract:
The process for recovering chemicals and energy from black liquor which is obtained in paper pulp production by means of chemical digestion of fiber raw material where gasification of the black liquor produces CO, CO.sub.2, CH.sub.4, H.sub.2 and H.sub.2 S, in gaseous form, and Na.sub.2 CO.sub.3, NaOH and Na.sub.2 S, in the form of drops of smelt comprising the steps of (a) cooling the resulting mixture of gas and smelt in a first stage by direct contact with a cooling liquid which is constituted principally by water, whereupon a part of the cooling liquid is volatilized, (b) separating the smelt drops off and dissolving them in a part of the cooling liquid with the formation of a liquid bath of green liquor and, in a second stage, (c) washing and saturating the gas from the first stage with moisture by direct contact with a washing liquid bath which is constituted principally by water and (d) recovering energy in the form of thermal energy and condensation heat from the moisture-saturated gas in an indirect condenser, wherein the contact between the gas and the cooling liquid in the first stage is substantially less than the contact between the gas and the washing liquid bath in the second stage.