Adsorption-based Claus tail gas treatment

A system for sulfur recovery from Claus tail gas, the system comprising:

• a hydrogenation reactor configured to convert sulfur-containing compounds in a Claus tail gas stream to hydrogen sulfide to produce a hydrogenated gas stream;
• a quench tower fluidically connected to the hydrogenation reactor and configured to receive the hydrogenated gas stream and produce a quenched gas stream by condensing liquid water into a water condensate stream;
• a first stage adsorption unit comprising a first stage adsorption vessel that, during a first stage adsorption cycle, is fluidically connected to the quench tower and configured to receive the quenched gas stream and to produce a first outlet gas stream by adsorbing water from the quenched gas stream;
• a second stage adsorption unit comprising a second stage adsorption vessel that, during a second stage adsorption cycle, is fluidically connected to the first stage adsorption vessel and configured to receive the first outlet gas stream and to produce a second byproduct gas stream by adsorbing hydrogen sulfide from the first outlet gas stream;
• a carbon dioxide separation element configured to receive at least a portion of the second byproduct gas stream and to separate the portion of the second byproduct gas stream into a carbon dioxide stream and an enriched nitrogen stream;
• in which the second stage adsorption vessel, during a second stage regeneration cycle, is configured to receive a portion of the enriched nitrogen stream.

A method for sulfur recovery, the method comprising:

• in a hydrogenation reactor, converting sulfur-containing compounds in a Claus tail gas stream to hydrogen sulfide to produce a hydrogenated gas stream comprising hydrogen sulfide, water, and at least one of carbon dioxide or nitrogen;
• feeding the hydrogenated gas stream to a quench tower to produce a quenched gas stream by condensing liquid water into a water condensate stream;
• feeding the quenched gas stream to a first stage adsorption vessel of a first stage adsorption unit to produce a first outlet gas stream by adsorbing water from the quenched gas stream;
• feeding the first outlet gas stream to a second stage adsorption vessel of a second stage adsorption unit to produce a second byproduct gas stream by adsorbing hydrogen sulfide from the first outlet gas stream;
• and
• regenerating the second stage adsorption vessel to produce a second outlet gas stream, in which regenerating the second stage adsorption vessel comprises feeding a portion of the second byproduct gas stream and a stream of nitrogen to the second stage adsorption vessel.