Process for producing and concentrating residual waste sulphite liquor

Claim 1

A PROCESS FOR PRODUCING RESIDUAL WASTE SULPHITE LIQUOR FROM A MIXTTURE OF FIBROUS MATERIAL AND WASTE SULPHITE COOKING LIQUOR AND CONCENTRATING AND DRYING THE RESIDUAL WASTE SULPHITE LIQUOR, WHICH PROCESS COMPRISES INTERMITTENTLY DISCHARGING A MIXTURE OF SULPHITE COOKING LIQUOR AND FIBROUS MATERIAL FROM A DIGESTING ZONE INTO A VESSEL WHERE GASES ARE FLASHED FROM SAID DISCHARGED MIXTTURE, CONDUCTING THE GASES TO AN ABSORBING ZONE, FLOWING CONCENTRATED WASTE SULPHITE LQUOR INTO THE ABSORBING ZONE FOR ABSORBING SAID GASES, FLOWING THE CONCENTRATED WASTE SULPHITE LIQUOR AND ABSORBED GASES FROM THE ABSORBING ZONE INTO SAID VESSEL AND INTO ADMIXTURE WITH THE DISCHARGED MIXTURE OF SULPHITE COOKING LIQUOR AND FIBROUS MATERIAL TO DILUTE THE LATTER MIXTURE, PASSING THE DILUTED MIXTURE OF COOKING LIQUOR AND FIBROUS MATERIAL TO A WASHING ZONE TO SEPARATE THE FIBROUS MATERIAL AND SULPHITE COOKING LIQUOR AND THEREBY OBTAINING A RESIDUAL WASTE SULPHITE LIQUOR, FLOWING THE RESIDUAL WASTE SULPHITE LIQUOR SUCCESSIVELY THROUGH A PLURALITY OF EVAPORATING ZONES TO SUCCESIVELY CONCENTRATE AND REDUCE THE TEMPERATURE OF THE WASTE SULPHITE LIQUOR AND PRODUCE VAPOR IN EACH OF SAID EVAPORATING ZONES, PASSING THE CONCENTRATED FROM THE LAST EVAPORATING ZONE, CONDENSING VAPOR FROM EACH EVAPORATING ZONE IN A CONDENSING ZONE COMMUNICATING THEREWITH BY PASSING IT IN HEAT EXCHANGE RELATIONSHIP IN SOME OF SAID LAST-MENTIONED CONDENSING ZONES WITH A PORTION OF SAID CONCENTRATED WASTE SULPHITE LIQUOR PASSED FROM THE LAST EVAPORATING ZONE OF SAID SUCCESSIVE ZONES AND IN HEAT EXCHANGE RELATIONSHIP WITH WATER IN THE OTHER CONDENSING ZONES ASSOCIATED WITH THE EVAPORATING ZONES, FLOWING ANOTHER PORTION OF THE CONCENTRATED WASTE SULPHITE LIQUOR TO SAID ABSORBING ZONE FOR USE IN ABSORBING GASES FLASHED FROM THE DISCHARGED MIXTURE OF FIBROUS MATERIAL AND SULPHITE COOKING LIQUOR, FEEDING ANOTHER PORTION OF THE CONCENTRATED WASTE SULPHITE LIQUOR FROM SAID LAST EVAPORATING ZONE INTO A HEATING ZONE TO HEAT THE CONCENTRATED WASTE SULPHITE LIQUOR UNDER PRESSURE TO PREVENT STEAMING OF THE LIQUOR CONCENTRATING SAID HEATED LIQUOR BY PASSING THE HEATED LIQUOR INTO A ZONE OF LOWER PRESSURE THAN SAID HEATING ZONE TO FLASH VAPOR FROM THE LIQUOR, AND DRYING. SAID FURNACE CONCENTRATED LIQUOR INTO SOLID FORM.