Fired equipment exhaust recovery system

Patent metadata

Field	Value
Publication number	US-2024091704-A1
Application number	US-202217932923-A
Country	US
Kind code	A1
Filing date	Sep 16, 2022
Priority date	Sep 16, 2022
Publication date	Mar 21, 2024
Grant date	—

Abstract

A system and a process for reducing greenhouse gas emissions are disclosed herein. The system may include a combustion zone, a catalytic converter, a methanation reactor, a compressor, a normal venting unit, a vacuum protection unit, and a control system. The process may include feeding a fuel, a methane-containing gas, and an oxygen-containing gas into a first reactor unit, and producing a combustion products stream comprising carbon monoxide, carbon dioxide, and water. The process may include cooling the combustion products stream via a cooling system, feeding the cooled exhaust stream and hydrogen to a second reactor unit. The second reactor unit may include a first catalyst for reacting oxygen with carbon monoxide to form carbon dioxide, and a second catalyst for reacting carbon dioxide with hydrogen to produce methane. The process may include recovering an effluent from the second reactor unit and feeding it to the first reactor unit.

First claim

What is claimed as new and desired to be protected by Letters Patent is:

1 . A process for reducing greenhouse gas emissions in fired equipment, the process comprising:
feeding a fuel, a methane-containing gas, and an oxygen-containing gas into a first reactor unit; producing a combustion products stream from the first reactor unit, the combustion products stream comprising carbon monoxide, carbon dioxide, and water; cooling the combustion products stream via a cooling system to produce a cooled exhaust stream; feeding the cooled exhaust stream and hydrogen to a second reactor unit, the second reactor unit comprising a first reaction zone containing a catalyst for catalytically reacting oxygen with carbon monoxide to form carbon dioxide and a second reaction zone containing a catalyst for reacting carbon dioxide with hydrogen to produce methane, and converting at least 80% of the carbon dioxide to methane; recovering an effluent from the second reactor unit comprising methane and carbon dioxide; and feeding the effluent to the first reactor unit as the methane-containing gas.

2 . The process of claim 1 , comprising converting at least 90% of the carbon dioxide to methane.

3 . The process of claim 1 , wherein the hydrogen is mixed with the cooled exhaust stream intermediate the first reaction zone and second reaction zone.

4 . The process of claim 1 , wherein the catalyst in the first reaction zone comprises one or more of platinum, palladium, and rhodium, and wherein the catalyst in the second reaction zone comprises one or more of ruthenium and cobalt.

5 . The process of claim 1 , wherein cooling comprising maintaining the first reaction zone and the second reaction zone at a temperature in a range from about 650° F. to about 720° F.

6 . The process of claim 1 , further comprising maintaining the first reaction zone and the second reaction zone at a pressure in a range from about 25 to about 45 psig.

7 . The process of claim 1 , wherein:
the fuel comprises one or more of coal, wood, or a hydrocarbon mixture; and the oxygen-containing gas is one or selected from the group consisting of air, oxygen-enriched air, and purified oxygen.

8 . The process of claim 1 , further comprising one or both of:
compressing the methane-containing gas; and condensing water out of the methane-containing gas.

9 . The process of claim 1 , further comprising one or both of:
feeding the oxygen-containing gas to the first reactor unit at a flow rate to provide greater than stoichiometric oxygen; and feeding hydrogen to the second reaction zone at a flow rate to provide less than stoichiometric hydrogen.

10 . The process of claim 1 , wherein the first reactor unit is a firebox comprising a radiant zone, a convective zone, and an exhaust zone, and wherein the second reactor unit is disposed in either the convective zone or the exhaust zone.

11 . The process of claim 10 , further comprising reducing a temperature of the combustion products stream, the cooled exhaust stream, or the effluent from the second reactor unit via indirect heat exchange with one or more of a water stream, a steam stream, a fuel stream, a hydrocarbon containing stream, or an oxygen-containing gas.

12 . The process of claim 1 , further comprising controlling a pressure of the cooled exhaust stream by opening or closing a valve of a vacuum protection unit.

13 . A system for reducing greenhouse gas emissions, the system comprising:
a combustion zone, comprising;
a fuel inlet, configured to feed a hydrocarbon fuel and a methane-containing gas into the combustion zone;
an oxygen gas inlet, configured to feed an oxygen-containing gas into the combustion zone;
wherein the combustion zone is configured to react the hydrocarbon fuel and the methane-containing gas with the oxygen-containing gas to produce a first exhaust stream comprising carbon monoxide, carbon dioxide, and water;
a catalytic converter, comprising;
a first exhaust inlet, configured to feed the first exhaust stream into the catalytic converter;
a first catalyst having activity for converting carbon monoxide to carbon dioxide;
wherein the catalytic converter is configured to convert carbon monoxide into carbon dioxide and produce a second exhaust stream comprising carbon dioxide and water;
a methanation reactor, comprising;
a second exhaust inlet, configured to feed the second exhaust stream into the methanation reactor;
a second catalyst having activity for reacting carbon dioxide with hydrogen to form methane;
wherein the methanation reactor is configured to react carbon dioxide with hydrogen and to convert at least 80% of the carbon dioxide to methane to produce a third exhaust stream comprising methane;
a compressor configured for receiving, compressing and feeding the third exhaust stream to the fuel inlet as the methane-containing gas; a normal venting unit, disposed intermediate the methanation reactor and the compressor, and configured to selectively divert a portion or an entirety of the third exhaust stream away from the compressor; a vacuum protection unit, disposed intermediate the normal venting unit and the compressor, the vacuum protection unit having a suction section and a discharge section, and configured to maintain the third exhaust stream at a pressure above a minimum set point pressure; and a control system, configured to control opening and closing of the normal venting unit.

14 . The system of claim 13 , further comprising one or more heat exchangers for recovering heat from one or more of the first exhaust stream, the second exhaust stream, and the third exhaust stream.

15 . The system of claim 13 , further comprising:
temperature sensors configured to measure a temperature of one or more of the first exhaust stream, the second exhaust stream, the third exhaust stream, the first catalyst, and the second catalyst; pressure sensors configured to measure a pressure of one or more of the first exhaust stream, the second exhaust stream, the third exhaust stream; gas analyzers to measure a composition of one or more of the first exhaust stream, the second exhaust stream, the third exhaust stream; flow rate sensors to measure a flow rate of one or more of a hydrogen feed, the oxygen-containing gas, the hydrocarbon fuel, and the methane-containing gas; and communication lines to transmit a signal from the temperature sensors, gas analyzers, flow rate sensors, and the pressure sensors to the control system.

16 . The system of claim 15 , wherein the control system is configured to intermittently stop hydrogen flow and open the normal venting unit and to start hydrogen flow and close the normal venting unit based upon one or more transmitted signals.

Assignees

• Saudi Arabian Oil Co

Inventors

• Alhazmi Shadi M
• Alahdal Ahmad M
• Alsowayigh Hamed S
• Almulla Abdullraheem U

Classifications

• B01D53/869 Primary

  Multiple step processes · CPC title

• B01D53/864 Primary

  Removing carbon monoxide or hydrocarbons · CPC title

• B01D53/8671

  Removing components of defined structure not provided for in B01D53/8603 - B01D53/8668 · CPC title

• B01D53/8696

  Controlling the catalytic process · CPC title

• B01J19/0013

  Controlling the temperature of the process · CPC title