Process for removing sulfur and sulfur compounds from the effluent of industrial processes

A process for removing sulfur dioxide from the effluent of an industrial process and for the production of elemental sulfur, the process comprising the steps of:

• (a) continuously passing an effluent stream into a Claus reactor;
• (b) generating a stream of hydrogen sulfide;
• (c) continuously passing the stream of hydrogen sulfide into the Claus reactor with the effluent;
• (d) continuously passing a stream of catalyst through the Claus reactor countercurrent to the hydrogen sulfide and the effluent;
• (e) continuously reducing the sulfur dioxide of the effluent to elemental sulfur in the Claus reactor in the presence of the catalyst at a reaction temperature of no more than about 320.degree. F. and at substantially atmospheric pressure;
• (f) continuously depositing the sulfur thus produced on the catalyst and in the Claus reactor;
• (g) continuously discharging the effluent from the Claus reactor substantially free of sulfur dioxide;
• (h) continuously passing the catalyst and deposited sulfur from the Claus reactor in a stream and introducing the stream into a sulfur condensation zone of a sulfur recovery vessel at substantially the reaction temperature in the Claus reactor;
• (i) continuously passing the stream of catalyst and deposited sulfur from the sulfur condensation zone into a sulfur vaporization zone of the sulfur recovery vessel;
• (j) continuously vaporizing the deposited sulfur in the sulfur vaporization zone by direct heat transfer with a heated recycle gas;
• (k) continuously condensing the vaporized sulfur to a liquid or a solid in the sulfur condensation zone by direct heat exchange with the stream of catalyst and deposited sulfur introduced from the Claus reactor to thereby heat the catalyst and deposited sulfur;
• (l) continuously passing the condensed sulfur from the sulfur condensation zone entrained in the recycle gas from the sulfur recovery vessel, the temperature of the condensed sulfur and recycle gas passed from the sulfur condensation zone approaching within about 50.degree. F. the temperature of the catalyst and deposited sulfur entering the sulfur condensation zone by reason of the heat transfer that takes place in the sulfur condensation zone;
• (m) continuously separating the sulfur from the recycle gas;
• (n) continuously recycling the recycle gas into a heat recovery zone of the sulfur recovery vessel after the sulfur separation step and passing such recycle gas countercurrent to the catalyst throughout the sulfur recovery vessel;
• (o) passing the catalyst from the sulfur vaporization zone through the heat recovery zone and directly transferring heat from the catalyst to the recycle gas in the heat recovery zone such that the temperature of the catalyst leaving the heat recovery zone approaches the temperature of the recycle gas entering the heat recovery zone within about 50.degree. F., the heat transferred to the recycle gas providing some of the heat used in the sulfur vaporization zone;
• and
• (p) continuously reintroducing the catalyst from the heat recovery zone into the Claus reactor as the catalyst that is passed through the Claus reactor.

A process for the purification of Claus plant tail gas to substantially free such tail gas of sulfur and compounds of sulfur prior to the discharge of the gas to atmosphere, the process comprising the steps of:

• (a) continuously passing a stream of Claus plant tail gas into an incinerator;
• (b) continuously passing a stream of air into the incinerator with the Claus plant tail gas;
• (c) continuously recycling through the incinerator a stream of heat transfer solids countercurrent to the tail gas and air and in direct heat transfer therewith;
• (d) continuously transferring heat from the heat transfer solids to the Claus plant tail gas and air in a first heat recovery zone of the incinerator;
• (e) after the heat transfer from the heat transfer solids to the tail gas, continuously oxidizing the sulfur and sulfur compounds in the tail gas to sulfur dioxide in an oxidation zone of the incinerator to form a stream including sulfur dioxide;
• (f) continuously transferring heat from the stream that includes sulfur dioxide in a second heat recovery zone of the incinerator by direct heat transfer with the countercurrent heat transfer solids to reduce the temperature of the stream that includes sulfur dioxide;
• (g) continuously introducing the stream that includes sulfur dioxide and a hydrogen sulfide stream into a Claus reactor and reducing the sulfur dioxide to condensed elemental sulfur therein in the presence of a catalyst and at a temperature no greater than about 320.degree. F. to generate a substantially sulfur-free treated gas stream and catalyst with deposited sulfur thereon, the sulfur depositing on the catalyst.
• (h) continuously passing the treated gas stream from the reactor to environment;
• (i) continuously passing the catalyst and deposited sulfur from the Claus reactor into a sulfur condensation zone of a catalyst regenerator;
• (j) continuously passing the stream of catalyst and deposited sulfur from the sulfur condensation zone into a sulfur vaporization zone of the catalyst regenerator;
• (k) continuously vaporizing the deposited sulfur in the sulfur vaporizaton zone by direct heat transfer with a heated recycle gas;
• (l) continuously condensing the vaporized sulfur to a liquid or a solid and cooling the recycle gas in the sulfur condensation zone by direct heat exchange with the stream of catalyst and deposited sulfur introduced from the Claus reactor to thereby heat the catalyst and deposited sulfur, the temperature of the recycle gas being no more than about 50.degree. F. higher at the end of the heating of the catalyst and deposited sulfur than the catalyst and deposited sulfur at the beginning of such direct heat exchange;
• (m) continuously passing the condensed sulfur from the sulfur condensation zone entrained in the recycle gas from the sulfur recovery vessel;
• (n) continuously separating the sulfur from the recycle gas;
• (o) continuously recycling the recycle gas into a heat recovery zone of the catalyst regenerator after the sulfur separation step and passing such recycle gas countercurrent to the catalyst throughout the catalyst regenerator;
• and
• (p) passing the catalyst from the sulfur vaporization zone into the heat recovery zone and directly transferring heat from the catalyst to the recycle gas, the catalyst temperature after such direct heat transfer being no more than 50.degree. F. higher than the recycle gas at the beginning of such direct heat transfer.