Production of so2 and o2 containing gases suitable for the production of elemental sulfur

Claim 1

IN A PROCESS FOR THE PRODUCTION OF AN SO2 AND O2 CONTAINING GAS MIXTURE SUITABLE FOR THE PRODUCTION OF ELEMENTAL SULFUR BY REDUCTION OF THE SO2 CONTAINED THEREIN FROM DILUTE SO2 CONTAINING GASES CONTAINING LESS THAN 30% OF SO2, THE STEPS WHICH COMPRISES COMPRESSING THE DILUTE SO2 CONTAINING GAS MIXTURE; LEADING SaID GAS MIXTURE IN A FIRST SWITCHING PERIOD OF OPERATION IN ONE DIRECTION THROUGH A FIRST REGENERATOR TO COOL THE GAS MIXTURE AND TO CONDENSE OUT THE SO2 THEREFROM, LEADING THE RESULTING COLD SO2-FREE GAS THROUGH A SECOND REGENERATOR TO COOL THIS REGENERATOR, COOLING AN O2 CONTAINING GAS IN COUNTER-CURRENT HEAT EXCHANGE WITH SAID COLD SO2-FREE GAS, EXPANDING THE COLD O2 CONTAINING GAS AND LEADING IT THROUGH A THIRD REGENERATOR TO EVAPORATE THE SO2 CONDENSED IN A FOREGOING SWITCHING PERIOD OF OPERATION; LEADING THE DILUTE SO2 CONTAINING GAS MIXTURE IN A SECOND SWITCHING PERIOD OF OPERATION IN ONE DIRECTION THROUGH THE SECOND REGENERATOR TO COOL THE GAS MIXTURE AND TO CONDENSE OUT THE SO2 THEREFROM, LEADING THE COLD SO2-FREE GAS THROUGH THE THIRD REGENERATOR TO COOL THIS REGENERATOR, COOLING AN O2 CONTAINING GAS IN COUNTERCURRENT HEAT EXCHANGE WITH SAID COLD SO2-FREE GAS, EXPANDING THE COLD O2 CONTAINING GAS AND LEADING IT THROUGH THE FIRST REGENERATOR TO EVAPORATE THE SO2 CONDENSED IN THE FOREGOING SWICTHING PERIOD OF OPERATION; LEADING THE DILUTE SO2 CONTAINING GAS MIXTURE IN A THIRD SWITCHING PERIOD OF OPERATION IN ONE DIRECTION THROUGH THE THIRD REGENERATOR TO COOL THE GAS MIXTURE AND TO CONDENSE OUT THE SO2 THEREFROM, LEADING THE COLD SO2-FREE GAS THROUGH THE FIRST REGENERATOR TO COOL THIS REGENERATOR, COOLING AN O2 CONTAINING GAS IN COUNTER-CURRENT HEAT EXCHANGE WITH SaID COLD SO2-FREE GAS, EXPANDING THE COLD O2 CONTAINING GAS AND LEADING IT THROUGH THE SECOND REGENERATOR TO EVAPORATE THE SO2 CONDENSED IN THE FOREGOING SWITCHING PERIOD OF OPERATION; THE COLD SO2 FREE GAS AND THE EXPANDED COLD O2 CONTAINING GAS IN EACH SWITCHING PERIOD BEING PASSED THROUGH THE RESPECTIVE REGENERATORS INDICATED IN A DIRECTION OPPOSITE TO THAT IN WHICH THE DILUTE SO2 CONTAINING GAS HAD BEEN LED THROUGH SUCH RESPECTIVE REGENERATORS IN THE FOREGOING SWITCHING PERIODS AND THE QUANTITY OF O2 CONTAINING GAS EMPLOYED IN EACH SWITCHING PERIOD OF OPERATION TO EVAPORATE THE SO2 CONDENSED IN THE FOREGOING SWITCHING PERIOD OF OPERATION BEING SUCH TO PRODUCE DIRECTLY A GAS CONTAINING ABOUT 30-80% BY SO2 AND ABOUT 8 TO 15% OF O2.