Production of sulfur from hydrogen sulfide and sulfur dioxide

Claim 1

IN A METHOD OF PRODUCING SULFUR FROM HYDROGEN SULFIDE AND SULFUR DIOXIDE INVOLVING PASSING A GASEOUS STREAM OF SAID REACTANTS THROUGH A BED OF CATALYST CONTAINED IN A CATALYTIC REACTION ZONE TO FORM SULFUR AND RECOVERING THE THUS FORMED SULFUR, THE IMPROVEMENT WHICH COMPRISES PASSING SAID STREAM THROUGH SAID ZONE AT ATMOSPHERIC PRESSURE; CONTROLLING THE AMOUNT OF ANY DILUENT GASES CONTAINED IN SAID STREAM PASSING TO SAID ZONE, INCLUDING ONE OF SAID REACANTS IN AMOUNTS GREATER THAN TWO MOLS OF HYDROGEN SULFIDE FOR EACH MOL OF SULFUR DIOXIDE, TO A VALUE NOT IN EXCESS OF ABOUT 60% BY VOLUME OF SAID STREAM, WHEREBY SAID STREAM OF REACTANTS IS CAPABLE OF SUSTAINING A REACTION TEMPERATURE OF ABOUT 400-600*C. IN SAID CATALYST; PASSING SAID STREAM OF REACTANTS THROUGH SAID CATALYST AT A SPACE VELOCITY OF AT LEAST ABOUT 0.66 CUBIC FOOT OF GAS AS MEASURED AT STANDARD CONDITIONS OF TEMPERATURE AND PRESSURE PER SECOND PER CUBIC FOOT OF CATALYST BUT AT SPACE VELOCITY WHICH IS BELOW THAT AT WHICH MIGRATION OF THE ZONE OF REACTION OUT OF THE CATALYST IN THE DIRECTION OF SAID STREAM IS AVOIDED; WHEREBY A REACTION ZONE HAVING A TEMPERATURE IN THE RANGE OF ABOUT 400-600*C. IS ESTABLISHED AN AUTOGENOUSLY SUSTAINED IN SAID CATALYST ZONE AND SUBSTANTIALLY ALL OF THE SULFUR FORMED BY THE REACTION IS IN A GASEOUS STATE AND POISONING OF THE CATALYST DUE TO SULFUR DEPOSITION THEREON IS AVOIDED DURING THE PROCESS; PASSING THE HOT PRODUCTS OF REACTION TO A COOLING ZONE; COOLING AND CONDENSING SULFUR FROM SAID HOT GASES IN SAID COOLING ZONE; AND RECOVERING THE THUS CONDENSED SULFUR.