Method for removal of sulfur deposited on a Claus catalyst

In a process for removal of sulfur from a gaseous stream containing hydrogen sulfide involving first recovering sulfur noncatalytically by burning said gaseous stream in a furnace followed by a waste heat boiler, and then further recovering sulfur catalytically by passing the effluent from the waste heat boiler through a series of Claus reactors with associated liquid sulfur condensers wherein one or more of the lead Claus reactors is operated in a so-called conventional temperature range which is higher than the sulfur dewpoint of the reacting gas and one or more of the following Claus reactors operates in a lower temperature range in which sulfur is strongly adsorbed on the catalyst, and wherein the temperature of the first Claus reactor is maintained sufficiently high to hydrolyze COS and CS.sub.2 and wherein the resulting effluent from the final conventional Claus reactor passes through a low temperature Claus step involving at least two interchangeable reactors, and wherein said conventional Claus effluent at all times passes through at least one of said interchangeable, low temperature reactors to further convert the reactants and condense the sulfur for an interval during which the other said interchangeable, low temperature reactor catalyst is regenerated by vaporization of the deposited sulfur followed by cooling of the sulfur-denuded catalyst, the improvement comprising:

• introducing initially into said interchangeable, low temperature Claus reactor about to be regenerated by removal of deposited sulfur a portion of the gaseous effluent from said first Claus reactor at a temperature of about 600.degree. to 650.degree. F. such as to heat the low temperature Claus catalyst and remove said deposited sulfur, and then having raised the temperature of said catalyst to about 600.degree. to 650.degree. F. introducing a hot gaseous stream into said interchangeable, low-temperature Claus reactor being regenerated such as to elevate the temperature of said regenerating catalyst bed to a value of about 700.degree. F. prior to cooling and returning said interchangeable, low temperature Claus reactor to the adsorption mode.