Process for producing sulphuric acid

Claim 1

IN A PROCESS FOR THE PRODUCTION OF SULFURIC ACID FROM HOT, DRY GAS CONTAINING A MINOR PROPORTION OF SO2, THE STEPS COMPRISING: (A) INTRODUCING SAID HOT, DRY GAS AT A TEMPERATURE ABOVE ABOUT 140* C. INTO A FIRST STAGE, (B) ULTIMATELY AND DIRECTLY CONTACTING SAID HOT, DRY GAS IN THE FIRST STAGE WITH DILUTE SULFURIC ACID WHICH IS AT A TEMPERATURE OF ABOUT 40* TO 70*C. AND HAS A CONCENTRATION BETWEEN ABOUT 45 TO 65% H2SO4 THEREBY COOLING AND HUMIDIFYING THE HOT, DRY GAS TO ABOUT 45 TO 100* C. AND PRODUCING SULFURIC ACID AT A TEMPERATURE OF AT LEAST ABOUT 110* C. AND A CONCENTRATION OF AT LEAST ABOUT 70% H2SSO4, (C) INTRODUCING THE GAS RESULTING FROM SAID FIRST STAGE INTO A SECOND STAGE AND THEREIN INTIMATELY AND DIRECTLY CONTACTING IT WITH AN SO2 CONVERSION CATALYST IMPREGNATED IN AN ABSORBENT IN THE PRESENCE OF OXYGEN WHILE SPRAYING WATER ONTO THE ABSORBENT, THEREBY PRODUCING DILUTE SULFURIC ACID, (D) PASSING THE GAS RESULTING FROM SAID SECOND STAGE INTO A THIRD STAGE AND THEREIN INTIMATELY AND DIRECTLY CONTACTING IT WITH PART OF THE SULFURIC ACID RESULTING FROM SAID FIRST STAGE THEREBY DRYING AND HEATING THE EXHAUST GAS FROM SAID SECOND STAGE, (E) COMBINING THE SULFURIC ACID RESLUTING FROM SAID SECOND AND THIRD STAGES AND INTRODUCING IT AS THE DILUTE SULFURIC ACID OF SAID FIRST STAGE, (F) EXHAUSTING THE GAS RESULTING FROM SAID THIRD STAGE TO THE ATMOSPHERE AND RECOVERING SULFURIC ACID FROM SAID FIRST STAGE AT A CONCENTRATION OF AT LEAST ABOUT 70% H2SO4.