Method and apparatus for reducing the ammonia concentration of sulfur recovery facility gas streams

A process for sulfur recovery comprising:

• subjecting a gas stream containing ammonia and hydrogen sulfide to a partial combustion step in a noncatalytic first combustion zone to produce a mixture including hydrogen sulfide, sulfur dioxide, nitrogen, water, and unconverted ammonia;
• introducing the thus-produced mixture into a Claus first catalytic reaction zone in which hydrogen sulfide and sulfur dioxide in the mixture react at a temperature above the dew point of sulfur to produce a hot effluent stream containing free sulfur;
• separating the thus-produced free sulfur from the hot effluent stream to produce a tail gas stream;
• forming free sulfur by contacting the tail gas stream with a catalyst at a temperature such that the preponderance of free sulfur thus formed is deposited on the catalyst;
• simultaneously depositing ammonium compounds on the catalyst;
• removing the thus-deposited free sulfur and ammonium compounds from the catalyst by passing a hot regeneration gas in contact with the catalyst to produce a regeneration effluent stream comprising free sulfur and ammonia;
• and
• reducing the concentration of ammonia in at least a portion of the regeneration effluent stream to produce a stream leaner in ammonia, said portion of the regeneration effluent stream being subjected to catalytic conditions effective for decomposition of ammonia to reduce the concentration of ammonia in said portion of the regeneration effluent stream to produce said stream leaner in ammonia.

A process for sulfur recovery from a gas stream containing ammonia and hydrogen sulfide comprising:

• forming free sulfur by contacting the gas stream with a catalyst at a temperature such that the preponderance of free sulfur thus formed is deposited on the catalyst;
• simultaneously depositing ammonium compounds on the catalyst;
• removing the thus-deposited free sulfur and ammonium compounds from the catalyst by passing a hot regeneration gas in contact with the catalyst to produce a regeneration effluent stream comprising free sulfur and ammonia;
• and
• reducing the concentration of ammonia in at least a portion of the regeneration effluent stream to produce a stream leaner in ammonia wherein said portion of the regeneration effluent stream is subjected to catalytic conditions effective for decomposition of ammonia to reduce the concentration of ammonia in said portion of the regeneration effluent stream to produce said stream leaner in ammonia.

A process for sulfur recovery from a gas stream containing ammonia and hydrogen sulfide comprising:

• forming free sulfur by contacting the gas stream with a catalyst at a temperature such that the preponderance of free sulfur thus formed is deposited on the catalyst;
• simultaneously depositing ammonium compounds on the catalyst;
• removing the thus-deposited free sulfur and ammonium compounds from the catalyst by passing a hot regeneration gas in contact with the catalyst to produce a regeneration effluent stream comprising free sulfur and ammonia;
• and
• reducing the concentration of ammonia in at least a portion of the regeneration effluent stream to produce a stream leaner in ammonia wherein the stream leaner in ammonia is mixed with the feed to at least one Claus reactor in a Claus catalytic reaction zone in which hydrogen sulfide and sulfur dioxide react at a temperature above the dew point of sulfur to produce free sulfur.

Apparatus for sulfur recovery from a stream comprising hydrogen sulfide and ammonia comprising:

• catalytic means for catalytically forming free sulfur from the gas stream under conditions effective for depositing a preponderance of the free sulfur thus formed on catalyst in said means and simultaneously depositing ammonium compounds on the catalyst;
• regeneration means for removing thus deposited free sulfur and ammonium compounds from the catalyst by passing a hot regeneration gas in contact with the catalyst to produce a regeneration effluent stream comprising free sulfur and ammonia at an outlet of the catalytic means;
• and
• ammonia concentration reducing means in flow communication with the outlet of the catalytic means for reducing the concentration of ammonia in at least a portion of the regeneration effluent stream and producing a stream leaner in ammonia, said ammonia concentration reducing means being means for catalytically decomposing ammonia in said portion of the regeneration effluent stream and producing the stream leaner in ammonia.