Methods for extracting heat and so2 from sulphite waste lye containing so2

Claim 1

A METHOD IN THE BOILING OF SULFITE CELLULOSE EMPLOYING LYE COMPRISING THE STEPS OF FIRST TERMINATING THE BOILING PROCESS AND THEN, WITH THE BOILER STILL UNDER APPROXIMATELY THE BOILING PRESSURE AND WITHOUT ANY SUBSTANTIAL PRECEDING REMOVAL OF LYE FROM THE BOILER, EJECTING THE BOILER CONTENTS, INCLUDING LYE AND PULP, DIRECTLY INTO A PULP BIN COMMUNICATING DIRECTLY WITH THE ATMOSPHERIC AIR WHILE COOLING SAID BOILER CONTENTS DURING SAID EJECTION SO AS TO CAUSE SAID CONTENTS TO ENTER SAID BIN AT A TEMPERATURE IN THE RANGE OF 90*C. TO 100*C. WITH SUBSTANTIALLY ALL OF THE SO2 OF THE BOILER CONTENTS REMAINING DISSOLVED IN THE LYE COLLECTED IN THE BIN, WITHDRAWING SAID HOT LYE CONTAINING SO2 FROM THE PULP IN SAID BIN, SUBJECTING A FLOW OF SAID WITHDRAWN LYE WITHOUT ANY SUBSTANTIAL PRECEDING COOLING THEREOF, OTHER THAN THAT DUE TO HEAT LOSSES IF ANY, IN SUCCESSION OF EACH OF SEVERAL SIMULTANEOUSLY OCCURING VACUUM PRESSURE LOWERING STEPS, EACH OF SAID STEPS INVOLVING A TEMPERATURE DECREASE OF THE LYE AND A CONSEQUENT RELEASE THEREFROM OF VAPOR CONTAINING SO2 AS THE FLOW OF LYE PASSES FROM ONE PRESSURE LOWERING STEP TO THE NEXT, EACH OF SAID STEPS BEING SUCCEEDED BY A CONDENSATION STEP IN WHICH SAID VAPOR IS CONDENSED AT APPROXIMATELY THE PRESSURE OF THE CORRESPONDING PRESSURE LOWERING STEP AND AT A TEMPERATURE CORRESPONDING THERETO WHILE INDIRECTLY COOLING SAID VAPOR BY A COOLING MEDIUM, UTILIZING SAID COOLING MEDIUM SUCCESSIVELY IN THE SAID SEVERAL SEPARATE CONDENSATION STEPS IN TURN FROM A CONDENSATION STEP PROCEEDING AT A LOWER PRESSURE AND TEMPERATURE TO A CONDENSATION STEP PROCEEDING AT A HIGHER PRESSURE AND TEMPERATURE, THEREBY HEATING SAID COOLING MEDIUM STAGEWISE TO A TEMPERATURE NEAR THAT OF THE HIGHEST TEMPERATURE CONDENSATION STEP AND WITHDRAWING THE UNCONDENSABLE SO2 GAS OBTAINED IN EACH OF SAID STEPS FROM THE SYSTEMS.

Claim 2

A METHOD IN THE BOILING OF SULFITE CELLULOSE EMPLOYING LYE COMPRISING THE STEPS OF FIRST TERMINATING THE BOILING PROCESS AND THEN, WITH THE BOILER STILL UNDER APPROXIMATELY THE BOILING PRESSURE AND WITHOUT ANY SUBSTANTIAL PRECEDING REMOVAL OF LYE FROM THE BOILER, EJECTING THE BOILER CONTENTS, INCLUDING LYE AND PULP, DIRECTLY INTO A PULP BIN COMMUNICATING DIRECTLY WITH THE ATMOSPHERIC AIR WHILE COOLING SAID BOILER CONTENTS DURING SAID EJECTION SO AS TO CAUSE SAID CONTENTS TO ENTER SAID BIN AT A TEMPERATURE IN THE RANGE OF 90*C. TO 100*C. WITH SUBSTANTIALLY ALL OF THE SO2 OF THE BOILER CONTENTS REMAINING DISSOLVED IN THE LYE COLLECTED IN THE BIN, WITHDRAWING SAID HOT LYE CONTAINING SO2 FROM THE PULP IN SAID BIN, SUBJECTING A FLOW OF SAID WITHDRAWN LYE WITHOUT ANY SUBSTANTIAL PRECEDING COOLING THEREOF, OTHER THAN THAT DUE TO HEAT LOSSES IF ANY, IN SUCCESSION OF EACH OF SEVERAL SIMULTANEOUSLY OCCURING VACUUM PRESSURE LOWERING STEPS, EACH OF SAID STEPS INVOLVING A TEMPERATURE DECREASE OF THE LYE AND A CONSEQUENT RELEASE THEREFROM OF VAPOR CONTAINING SO2 AS THE FLOW OF LYE PASSES FROM ONE PRESSURE LOWERING STEP TO THE NEXT, EACH OF SAID STEPS BEING SUCCEEDED BY A CONDENSATION STEP IN WHICH SAID VAPOR IS CONDENSED AT APPROXIMATELY THE PRESSURE OF THE CORRESPONDING PRESSURE LOWERING STEP AND AT A TEMPERATURE CORRESPONDING THERETO WHILE INDIRECTLY COOLING SAID VAPOR BY A COOLING MEDIUM, UTILIZING SAID COOLING MEDIUM SUCCESSIVELY IN THE SAID SEVERAL SEPARATE CONDENSATION STEPS IN TURN FROM A CONDENSATION STEP PROCEEDING AT A LOWER PRESSURE AND TEMPERATURE TO A CONDENSATION STEP PROCEEDING AT A HIGHER PRESSURE AND TEMPERATURE, THEREBY HEATING SAID COOLING MEDIUM STAGEWISE TO A TEMPERATURE NEAR THAT OF THE HIGHEST TEMPERATURE CONDENSATION STEP AND WITHDRAWING THE UNCONDENSABLE SO2 GAS OBTAINED IN EACH OF SAID STEPS FROM THE SYSTEMS.