Patent ID: 6962680

Claim:
A method for removing sulfur compounds from an impurity gas containing sulfur compounds including hydrogen sulfide and mercaptans, carbon dioxide and aromatic hydrocarbons, comprising the steps of: transferring the impurity gas to a concentration process in which the impurity gas is separated into a concentrated gas containing hydrogen sulfide as a main substance, and a residual gas containing carbon dioxide as a main substance, mercaptans and aromatic hydrocarbons; transferring the concentrated gas to a Claus reaction process in which hydrogen sulfide is recovered as an elementary sulfur, and an off-gas discharged from the Claus reaction process is heated to be a temperature between at least equal to the temperature at which the off-gas is discharged from the Claus reaction process and 700° C. using a heating unit; introducing the heated off-gas into a mixing unit which is provided separately from the heating unit, to be mixed with the residual gas; transferring the resultant mixed gas to a hydrogenation reaction process in which sulfur compounds including mercaptans, are converted into hydrogen sulfide under the presence of a reduction catalyst; and separating the converted hydrogen sulfide and returning the separated hydrogen sulfide to the Claus reaction process.