Process and apparatus for production of elemental sulfur

In the process for reacting a gas containing hydrogen sulfide and sulfur dioxide to form elemental sulfur via the Claus reaction, wherein said gas is passed through a plurality of solid catalyst beds at an elevated temperature which is below the sulfur dew point, to thereby charge said catalyst beds with at least a part of the sulfur formed and wherein said catalyst beds are subsequently regenerated by passing heated gas therethrough, the improvement which comprises:

• (A) passing the hydrogen sulfide and sulfur dioxide containing gas during a charging phase through a first catalyst bed at a temperature below the sulfur dew point so as to charge the bed with sulfur;
• (B) heating all effluent from the first catalyst bed during a first part of the first catalyst bed charging phase to a temperature above the sulfur dew point;
• (C) passing said heated effluent to a sulfur-containing second catalyst bed in order to vaporize sulfur from said second catalyst bed and to thereby regenerate said second catalyst bed;
• (D) discontinuing the heating of said first catalyst bed effluent during a second part of the first catalyst bed charging phase such that the temperature of said effluent falls below the sulfur dew point;
• (E) passing said cooler effluent through said regenerated second catalyst bed to thereby cool said regenerated second catalyst bed;
• (F) passing the effluent from the second catalyst bed through a sulfur condenser so as to condense vaporized sulfur contained in the effluent;
• (G) withdrawing sulfur condenser waste gas directly from the process;
• and
• (H) reversing the direction of flow of the gas through said first and second catalyst beds after the first catalyst bed has been charged with sulfur.