Method of producing sulphite acid

Claim 1

A PROCESS FOR RECOVERING SO2 FROM SULFITE PROCESS DIGESTER RELIEF GASES PERIODICALLY RELIVED FROM A DIGESTER AND PRODUCING COOKING ACID LIQUOR FROM RAW ACID LIQUOR DELIVERED FROM A RAW ACID LIQUOR PLANT WITHOUT FEEDING SAID RELIEF GASES TO SAID PLANT COMPRISING PASSING SAID GASES AT EACH TIME OF RELIEF DIRECTLY THROUGH A BODY OF STRENGTHENED RAW SULFITE ACID LIQUOR IN A FIRST ABSORPITON ZONE TO ABSORB A PORTION OF THE SO2 THERIN TO FORM COOKING ACID LIQUOR; PASSING THE UNABSORBED GASES FROM SAID FIRST ABSORPTION ZONE TO A SECOND AB SORPTION ZONE CONTAINING A BODY OF RAW SULFITE ACID LIQUOR TO RECOVER THE REMAINING SO2 CONTAINED THEEIN AND TO PRODUCE STRENGTHENED RAW SULFITE LIQUOR, EXHAUSTING THE UNABSORBED GASES FROM SAID SECOND ABSORPTION ZONE TO THE ATMOSPHERE, FEEDING RAW ACID LIQUOR, THE ACID LIQUOR BEING PREPARED IN SAID PLANT AND INDEPENDENTLY OF SAID ZONES TO SAID SECOND ABSORPTION ZONE, FEEDING SAID STRENGTHENED LIQUOR FROM SAID SECOND ABSORPTION ZONE TO SAID FIRST ABSORPTION ZONE, AND ACCUMULATING A BULK OF RAW ACID LIQUOR IN SAID SECOND ZONE BEING EFFECTED TIMES, THE ABSORPTION IN SAID SECOND ZONE BEING EFFECTED BY PASSING SAID GAS INTO A CLOSED GAS SPACE IN CONTACT WITH SAID ACCUMULATED BULK OF RAW ACID LIQUOR, AND PROJECTING LIQUOR FROM THE UPPER PORTION OF SAID BULK INTO SAID GAS SPACE WHEREBY INTIMATE CONTACT BETWEEN SAID GAS AND SAID LIQUOR IS EFFECTED, TEH AMOUNT OF SAID RAW ACID LIQUOR DELIVERED TO SAID SECOND ABSORPTION ZONE FROM SAID RAW ACID PLANT DURING THE DIGESTER RELIEF PERIOD BEING SUFFICIENT TO ABOSRB ONLY A PORTION OF THE SO2 CONTAINED IN THE GASES CONTACTED THEREIN AND THE AMOUNT OF LIQUOR ACCUMULATED IN SAID BULK BETWEEN SAID RELIEF TIMES BEING SUFFICIENT TO ABSORB SUBSTANTIALLY ALL THE REMAINING SO2 CONTAINED IN SAID GASES, SAID DIGESTER RELIEF GASES CONTACTING ACID LIQUOR SOLELY IN SAID FIRST AND SEOCND ABSORPTION ZONES.