Plasma treatment in sulfur recovery
A system and method for removing sulfur compounds from gas, including providing a feed gas having sulfur compounds including hydrogen sulfide (H 2 S) to a sulfur recovery unit (SRU) that has a furnace or a non-thermal plasma (NTP) reactor, discharging an SRU tail gas having H 2 S from the SRU to a tail gas treatment (TGT) unit having a hydrogenation reactor, a quench tower, and a TGT NTP reactor, converting sulfur compounds in the SRU tail gas in the hydrogenation reactor into H 2 S, discharging a process gas having H 2 S from the hydrogenation reactor to the quench tower and removing water vapor from the process gas in the quench tower, discharging an overhead gas having H 2 S from the quench tower to the TGT NTP reactor, and converting H 2 S in the TGT NTP reactor into hydrogen (H 2 ) and elemental sulfur.
1 . A method of removing sulfur compounds from gas, comprising:
providing a feed gas comprising sulfur compounds including hydrogen sulfide (H 2 S) to a furnace of a sulfur recovery unit (SRU);
reacting H 2 S with sulfur dioxide (SO 2 ) in the furnace and in catalytic converters of the SRU to give elemental sulfur and water (H 2 O);
condensing elemental sulfur vapor in condenser heat exchangers of the SRU and discharging elemental liquid sulfur from the condenser heat exchangers for recovery;
discharging an SRU tail gas comprising H 2 S from the SRU to a hydrogenation reactor of a tail gas treatment (TGT) unit;
converting sulfur compounds in the SRU tail gas in the hydrogenation reactor into H 2 S;
discharging a process gas comprising H 2 S from the hydrogenation reactor to a quench tower of the TGT unit and removing water vapor from the process gas in the quench tower;
discharging an overhead gas comprising H 2 S from the quench tower to a non-thermal plasma (NTP) reactor of the TGT unit;
converting H 2 S in the NTP reactor into hydrogen (H 2 ) and elemental sulfur; and
discharging a gas from an NTP unit comprising the NTP reactor to a thermal oxidizer, wherein the gas comprises the process gas as treated in the NTP reactor minus the elemental sulfur that is recovered.
2 . The method of claim 1 , wherein the feed gas comprises acid gas comprising H 2 S and carbon dioxide (CO 2 ), and wherein the catalytic converters are disposed operationally downstream of the furnace.
3 . The method of claim 1 , wherein the sulfur compounds converted into H 2 S in the hydrogenation reactor comprise sulfur dioxide (SO 2 ), carbonyl sulfide (COS), carbon disulfide (CS 2 ), or elemental sulfur, or any combinations thereof, and wherein the process gas discharged from the hydrogenation reactor comprises the SRU tail gas as subjected to hydrogenation in the hydrogenation reactor.
4 . The method of claim 1 , wherein discharging the process gas comprises discharging the process gas comprising H 2 S from the hydrogenation reactor through a cooler heat exchanger to the quench tower, wherein the overhead gas comprises the process gas without the water vapor removed in the quench tower.
5 . The method of claim 1 , wherein the converting of the H 2 S in the NTP reactor comprises a dissociation reaction of the H 2 S into H 2 and elemental sulfur in a plasma discharge zone of the NTP reactor, and wherein the method comprises recovering elemental sulfur generated by the dissociation reaction.
6 . The method of claim 5 , comprising:
recovering H 2 as permeate through a hydrogen-selective membrane of the NTP reactor; and
discharging a gas from an NTP unit comprising the NTP reactor to a thermal oxidizer, wherein the gas comprises the process gas as treated in the NTP reactor minus the elemental sulfur that is recovered and minus the H 2 that is recovered.
7 . The method of claim 5 , comprising providing oxygen (O 2 )-enriched air via an air separation unit (ASU) to the furnace, wherein N 2 loading on the NTP reactor is less than if ambient air not enriched in O 2 is provided to the furnace, and wherein flow rate of the SRU tail gas is less than if ambient air not enriched in O 2 is provided to the furnace.