High purity nitrogen/hydrogen production from an exhaust stream
AssigneeExxonMobil Research and Engineering Company
InventorsNarasimhan Sundaram, Hans Thomann
Life of this patent
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Abstract
Methods are provided for the production of nitrogen, hydrogen, and carbon dioxide from an exhaust gas. Exhaust gas from combustion in a fuel rich (or reducing) atmosphere is primarily composed of CO2, CO, N2, H2O, and H2. CO may be converted to CO2 and H2 via the water gas shift reaction. Carbon dioxide may then be effectively separated from nitrogen and hydrogen to produce a carbon dioxide stream and a nitrogen/hydrogen stream. The nitrogen/hydrogen stream may then be effectively separated to produce a high purity nitrogen stream and a high purity hydrogen stream. The process may be done in any order, such as separating the nitrogen first or the carbon dioxide first.
Claims11
A method for production of H2, N2, and CO2 from an exhaust stream, comprising:
- passing an exhaust stream comprising at least about 40-80 vol % N2, at least about 5-30 vol % CO2, and at least about 1-20% H2 into a CO2 swing adsorption reactor comprising a CO2 adsorbent material selective for CO2 over N2 and H2, the exhaust stream having a pressure between about 10 bara (about 1.0 MPaa) to about 30 bara (about 3.0 MPaa), wherein the exhaust stream comprising a power plant flue stream, a refinery flue stream, or a combination thereof;
- adsorbing CO2 on the CO2 adsorbent material;
- recovering a N2 and H2 stream from a forward end of the CO2 swing adsorption reactor, the recovered N2 and H2 stream having a pressure that differs from the pressure of the exhaust stream by about 0.5 bara (about 50 kPa) or less;
- reducing the pressure in the CO2 swing adsorption reactor to a pressure from about 1.0 bara (about 0.1 MPaa) to about 4.0 bara (about 0.4 MPaa) by outputting a blow down stream from at least one end of the CO2 swing adsorption reactor;
- and
- purging the CO2 swing adsorption reactor with a steam purge at a pressure from about 1.0 bara (about 0.1 MPaa) to about 4.0 bara (about 0.4 MPaa) to generate a CO2 recovery stream, the CO2 recovery stream comprising at least about 90% of the CO2 present in the exhaust stream, the steam purge containing less than about 1.0 moles of H2O per mole of CO2 in the reactor exhaust stream;
- passing the N2 and H2 stream into a N2 swing adsorption reactor comprising a N2 adsorbent material selective for N2 over CO2 and H2;
- adsorbing N2 on the N2 adsorbent material;
- recovering an H2 stream having a purity of at least 95% from a forward end of the N2 swing adsorption reactor, the recovered H2 stream having a pressure that differs from the pressure of the N2 and H2 stream by about 0.5 bara (about 50 kPa) or less;
- reducing the pressure in the N2 swing adsorption reactor to a pressure from about 1.0 bara (about 0.1 MPaa) to about 4.0 bara (about 0.4 MPaa) by outputting a blow down stream from at least one end of the N2 swing adsorption reactor;
- and
- purging the N2 swing adsorption reactor with a portion of the H2 stream at a pressure from about 1.0 bara (about 0.1 MPaa) to about 4.0 bara (about 0.4 MPaa) to generate a N2 recovery stream, the N2 recovery stream comprising at least about 90% of the N2 present in the exhaust stream.
Dependencies are inferred from the claim text.