US-12623904-B2 - Removal of sulfur compounds from gas

US12623904B2US 12623904 B2US12623904 B2US 12623904B2US-12623904-B2

Abstract

A system and method for removing sulfur compounds from gas, including discharging tail gas having sulfur compounds from a sulfur recovery unit (SRU) to a non-thermal plasma (NTP) catalytic unit including an NTP reactor, providing oxidant to the NTP reactor and placing the oxidant in an NTP state in the NTP reactor to give an oxidative reactive species formed from the oxidant, converting (oxidizing) the sulfur compounds with the oxidative reactive species and catalyst in the NTP catalytic unit into sulfur oxides (SO x ) to discharge the tail gas as treated having the formed SO x without the sulfur compounds that were converted. The SO x is absorbed into water in a quench tower to give the tail gas beneficially having only small amounts (e.g., less than 200 ppmv) of sulfur compounds. SO x may be degassed from water discharged from the quench tower and sent to the SRU furnace.

Inventors

Mohammad Saad AlQahtani
Seung-hak Choi

Assignees

SAUDI ARABIAN OIL COMPANY

Dates

Publication Date: 20260512
Application Date: 20221003

Claims (11)

1 . A method of removing sulfur compounds from a gas, comprising: discharging a tail gas comprising sulfur compounds from a sulfur recovery unit (SRU) to a non-thermal plasma (NTP) catalytic unit comprising an NTP reactor; providing an oxidant to the NTP reactor and placing the oxidant in an NTP state in the NTP reactor to give an oxidative reactive species formed from the oxidant; oxidizing the sulfur compounds with the oxidative reactive species and catalyst in the NTP catalytic unit into sulfur oxides (SOx); discharging process gas from the NTP catalytic unit to a quench tower, the process gas comprising the tail gas having the SOx formed by oxidizing the sulfur compounds; absorbing SOx from the process gas into water in the quench tower; discharging from the quench tower an overhead gas comprising the process gas without the SOx absorbed into the water; discharging from the quench tower a bottoms stream comprising the water having the absorbed SOx to a membrane degassing unit comprising a membrane; removing SOx from the water in the membrane degassing unit; and discharging the SOx as removed from the membrane degassing unit to a reaction furnace of the SRU.
2 . The method of claim 1 , wherein the overhead gas comprises less than 100 part per million by volume (ppmv) of SOx and less than 100 ppmv of sulfur compounds, wherein the water having the absorbed SOx is acidic water, wherein the SRU comprises a Claus system, wherein the tail gas comprises Claus tail gas, and wherein the overhead gas does not comprise water vapor in the process gas that condensed in the quench tower.
3 . The method of claim 1 , comprising oxidizing carbon monoxide (CO) in the tail gas with the catalyst and the oxidative reactive species in the NTP catalytic unit into carbon dioxide (CO2), wherein the sulfur compounds in the tail gas oxidized in the NTP catalytic unit into SOx comprise at least one of hydrogen sulfide (H2S), carbonyl sulfide (COS), carbon disulfide (CS2), elemental sulfur(S) vapor, or methanethiol (CH3SH), and wherein the SOx comprises sulfur dioxide (SO2) and sulfur trioxide (SO3).
4 . The method of claim 1 , wherein the oxidant comprises water or oxygen gas (O2), or both, and wherein the oxidative reactive species comprises hydroxide (OH), oxygen (O), or ozone (O3), or any combinations thereof.
5 . The method of claim 4 , wherein the oxidant comprises air providing at least some of the oxygen gas (O2) and at least some of the water.
6 . The method of claim 1 , comprising flowing the tail gas having sulfur compounds discharged from the SRU through the NTP reactor in the NTP catalytic unit, wherein oxidizing the sulfur compounds with the oxidative reactive species and the catalyst occurs in the NTP reactor, and wherein the NTP reactor comprises an NTP catalytic reactor having the catalyst.
7 . The method of claim 6 , wherein at least a portion of the catalyst is disposed in a plasma discharge zone of the NTP catalytic reactor.
8 . The method of claim 6 , wherein the tail gas comprising sulfur compounds discharged from the SRU comprises at least some of the oxidant provided to the NTP catalytic reactor.
9 . The method of claim 1 , comprising: flowing the tail gas having sulfur compounds discharged from the SRU through a vessel in the NTP catalytic unit, wherein the vessel has the catalyst; injecting the oxidative reactive species from the NTP reactor into the vessel, wherein oxidizing the sulfur compounds with the oxidative reactive species and the catalyst occurs in the vessel.
10 . The method of claim 9 , wherein the vessel is a conduit having the catalyst.
11 . The method of claim 1 , comprising discharging from the membrane degassing unit to the quench tower the bottoms stream minus the SOx removed.

Description

TECHNICAL FIELD This disclosure relates to removal of sulfur compounds from gas, such as from industrial tail gas streams. BACKGROUND Hydrogen sulfide can be a byproduct of processing natural gas and refining sulfur-containing crude oils. Other industrial sources of hydrogen sulfide may include pulp and paper manufacturing, chemical production, waste disposal, and so forth. In certain instances, hydrogen sulfide can be considered a precursor to elemental sulfur. Sulfur recovery may refer to conversion of hydrogen sulfide (H2S) to elemental sulfur, such as in a sulfur recovery unit (SRU), e.g., Claus system. The most prevalent technique of sulfur recovery is the Claus system, which may be labeled as the Claus process, Claus plant, Claus unit, and the like. The Claus system includes a thermal reactor (e.g., a furnace or reaction furnace) and multiple catalytic reactors to convert H2S into elemental sulfur. A conventional Claus system can recover between 95% and 98% of H2S. The percent recovery may depend on the number of Claus catalytic reactors. The tail gas from the Claus system may have the remaining (residual) H2S, such 2% to 5% of the equivalent H2S in the feed gas. The Claus tail gas can be treated to recover this remaining H2S equivalent. In particular, a tail gas treatment (TGT) unit, also known as TGTU, can increase sulfur recovery to or above 99.9%. Environmental regulations regarding sulfur oxides (SOx) emissions may place requirements on sulfur recovery efficiency in commercial sulfur recovery. Carbon dioxide is the primary greenhouse gas emitted through human activities. Carbon dioxide (CO2) may be generated in various industrial and chemical plant facilities. At such facilities, avoiding or reducing emissions of CO2 may beneficially decrease the CO2 footprint of the facility. SUMMARY An aspect relates to a method of removing sulfur compounds from a gas, including discharging a tail gas having sulfur compounds from a sulfur recovery unit (SRU) to a non-thermal plasma (NTP) catalytic unit including an NTP reactor, providing an oxidant to the NTP reactor and placing the oxidant in an NTP state in the NTP reactor to give an oxidative reactive species formed from the oxidant, oxidizing the sulfur compounds with the oxidative reactive species and catalyst in the NTP catalytic unit into sulfur oxides (SOx), and discharging process gas from the NTP catalytic unit to a quench tower, the process gas including the tail gas minus the sulfur compounds oxidized into SOx and having the SOx formed by oxidizing the sulfur compounds. The method includes absorbing SOx from the process gas into water in the quench tower, discharging from the quench tower an overhead gas having the process gas without the SOx absorbed into the water, discharging from the quench tower a bottoms stream including the water having the SOx as absorbed to a membrane degassing unit having a membrane, and removing SOx from the water in the membrane degassing unit. The method includes discharging the SOx as removed from the membrane degassing unit to a reaction furnace of the SRU. Another aspect is a system for removing sulfur compounds from a gas, including an NTP catalytic unit operationally coupled to an SRU to receive SRU tail gas having sulfur compounds discharged from the SRU and oxidize the sulfur compounds via a catalyst and an oxidative reactive species into SOx. The NTP catalytic unit includes an NTP reactor to receive an oxidant and place the oxidant in an NTP state to give the oxidative reactive species formed from the oxidant. The system includes a quench tower operationally coupled to the NTP catalytic unit to receive process gas discharged from the NTP catalytic unit and absorb SOx from the process gas into water, and discharge an overhead gas having the process gas without the SOx absorbed into the water and discharge a bottoms stream including the water having the SOx as absorbed. The system includes a membrane degassing unit comprising a membrane operationally coupled to the quench tower to receive the bottom stream and remove SOx from the bottom stream and discharge the SOx as removed to a reaction furnace of the SRU. The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram of a system for removing sulfur compounds from a gas. FIG. 2 is a diagram of an example of the quench tower of FIG. 1 with associated pump and cooler heat exchanger. FIG. 3 is a diagram of a system for removing sulfur compounds from a gas. FIG. 4 is a diagram of an NTP catalytic unit having an NTP catalytic reactor. FIG. 5 is a diagram of an NTP catalytic unit having an NTP reactor (not an NTP catalytic reactor) and a vessel. FIGS. 6-8 are diagrams of NTP reactors that each are a dielectric barrier discharge (DBD) reactor. FIGS. 9-10 are diagrams o