Synthesis gas production by steam methane reforming
A synthesis gas plant for producing a synthesis gas, where the synthesis gas plant includes a reforming section arranged to receive said feed gas and provide a combined synthesis gas, wherein said reforming section includes an electrically heated reforming reactor, a fired reforming reactor and an optional third reforming reactor. The reforming section is arranged to output a combined synthesis gas. An optional post processing unit downstream the reforming section is arranged to receive said combined synthesis gas stream and provide a post processed synthesis gas stream. A gas separation unit arranged to separate the combined synthesis gas stream or the post processed synthesis gas stream into a condensate, a product synthesis gas and an off-gas. At least a part of the off-gas is recycled from said gas separation unit to said one or more burners. Also, a process for producing synthesis gas from a feed gas comprising hydrocarbons.
1. A synthesis gas plant for producing a synthesis gas, said synthesis gas plant comprising:
a reforming section arranged to receive a feed gas and provide a combined synthesis gas, wherein said reforming section comprises:
an electrically heated steam methane reforming reactor housing a first catalyst, said electrically heated steam methane reforming reactor being arranged for receiving a first part of said feed gas comprising hydrocarbons and generating a first synthesis gas stream,
a fired reforming reactor in parallel with said electrically heated steam methane reforming reactor, said fired reforming reactor comprising one or more tubes housing a second catalyst, said fired reforming reactor further comprising one or more burners for providing heat to said one or more tubes, said one or more tubes being arranged for receiving a second part of said feed gas comprising hydrocarbons and outputting a second synthesis gas stream, wherein said reforming section is arranged to output a combined synthesis gas stream comprising said first and/or second synthesis gas streams or part thereof,
an optional post processing unit downstream the reforming section, where the optional post processing unit is arranged to receive the combined synthesis gas stream and provide a post processed synthesis gas stream,
a gas separation unit arranged to separate said combined synthesis gas stream or said post processed synthesis gas stream into at least a condensate, a product synthesis gas and an off-gas, and
connections for recycling at least part of the said off-gas from said gas separation unit to said one or more burners,
wherein said electrically heated steam methane reforming reactor comprises:
a pressure shell housing an electrical heating unit arranged to heat said first catalyst, where said first catalyst comprises a catalytically active material operable to catalyzing steam reforming of said first part of said feed gas, wherein said pressure shell has a design pressure of between 5 and 45 bar,
a heat insulation layer adjacent to at least part of the inside of said pressure shell, and
at least two conductors electrically connected to said electrical heating unit and to an electrical power supply placed outside said pressure shell,
wherein said electrical power supply is dimensioned to heat at least part of said first catalyst to a temperature of at least 500° C. by passing an electrical current through said electrical heating unit.
2. The synthesis gas plant according to claim 1 , wherein said reforming section furthermore comprises an autothermal reforming reactor downstream said electrically heated steam methane reforming reactor and said fired reforming reactor, wherein said autothermal reforming reactor comprises a third catalyst and is arranged to receive said first and/or second synthesis gas or part thereof and to provide an auto-reformed synthesis gas stream, wherein the auto-reformed synthesis gas is output from the reforming section as at least part of the combined gas stream.
3. The synthesis gas plant according claim 1 , wherein said reforming section furthermore comprises a gas heated steam methane reforming reactor in parallel to said electrically heated steam methane reforming reactor and said fired reforming reactor, wherein said gas heated steam methane reforming reactor comprises a fourth catalyst and being operable to receive a third part of the feed gas comprising hydrocarbons and to utilize at least part of said first and/or second synthesis gas streams as heating media in heat exchange within said gas heated steam methane reforming reactor, said gas heated steam methane reforming reactor being arranged for generating a third synthesis gas stream and outputting said third synthesis gas stream from said reforming section as at least part of said combined synthesis gas.
4. The synthesis gas plant according claim 2 , wherein said reforming section furthermore comprises a gas heated steam methane reforming reactor in parallel to said electrically heated steam methane reforming reactor, said fired reforming reactor and said autothermal reforming reactor, wherein said gas heated steam methane reforming reactor comprises a fourth catalyst and being operable to receive a third part of the feed gas comprising hydrocarbons and to utilize at least part of said auto-reformed synthesis gas stream as heating medium in heat exchange within said gas heated steam methane reforming reactor, said gas heated steam methane reforming reactor being arranged for generating a third synthesis gas stream and outputting said third synthesis gas stream from said reforming section as at least part of said combined synthesis gas.
5. The synthesis gas plant according to claim 1 , wherein said post processing unit is a post conversion unit having an inlet for allowing inletting heated CO 2 addition to the combined synthesis gas upstream the post conversion unit and housing a fifth catalyst active for catalyzing steam methane reforming, methanation and reverse water gas shift.
6. The synthesis gas plant according to claim 1 , wherein said post processing unit is a water gas shift unit arranged to carry out water gas shift reaction.
7. The synthesis gas plant according to claim 1 , wherein said fired reforming reactor is a steam methane reforming reactor.
8. The synthesis gas plant according to claim 1 , wherein said fired reforming reactor is a convective reforming reactor, wherein flue gas from said one or more burners is used as heat exchange medium within the convective reforming reactor.
9. The synthesis gas plant according to claim 1 , wherein said electrical heating unit comprises a macroscopic structure of electrically conductive material, where said macroscopic structure supports a ceramic coating and said ceramic coating supports said catalytically active material.
10. A process for producing synthesis gas in the synthesis gas plant of claim 1 , said process comprising the steps of:
inletting a first part of a feed gas comprising hydrocarbons to said electrically heated steam methane reforming reactor and carrying out steam methane reforming to provide a first synthesis gas stream,
inletting a second part of the feed gas comprising hydrocarbons to said fired reforming reactor, and carrying out steam methane reforming to provide a second synthesis gas stream,
providing a fuel gas to said one or more burners to provide heat for steam methane reforming reaction within said one or more tubes of said fired reforming reactor,
outputting a combined synthesis gas stream comprising said first and/or second synthesis gas streams or part thereof from said reforming section,
optionally, in a post processing unit downstream said electrically heated reforming reactor and said fired reforming reactor, post processing said combined synthesis gas stream to provide a post processed synthesis gas stream,
separating said combined synthesis gas stream or said post processed synthesis gas stream into a condensate, a product synthesis gas and an off-gas in a gas separation unit downstream said post processing unit, and
recycling at least part of said off-gas from said gas separation unit as fuel gas to said one or more burners,
wherein said process further comprises the steps of:
pressurizing said first part of said feed gas to a pressure of between 5 and 45 bar upstream said electrically heated steam methane reforming reactor,
passing an electrical current through said electrical heating unit thereby heating at least part of said first catalyst to a temperature of at least 500° C.
11. The process according to claim 10 , wherein said reforming section furthermore comprises an autothermal reforming reactor downstream said electrically heated steam methane reforming reactor and said fired reforming reactor, wherein said process furthermore comprises the steps of:
inletting said first and/or second synthesis gas or part thereof into said autothermal reforming reactor,
inletting an oxidant gas into said autothermal reforming reactor,
generating an auto-reformed synthesis gas stream over a third catalyst within said autothermal reforming reactor, and
outputting said auto-reformed synthesis gas from the reforming section as the combined gas stream.
12. The process according to claim 10 , wherein said reforming section furthermore comprises a gas heated steam methane reforming reactor in parallel to said electrically heated steam methane reforming reactor and said fired reforming reactor, wherein said gas heated steam methane reforming reactor comprises a fourth catalyst, said process furthermore comprising the steps of:
inletting a third part of the feed gas comprising hydrocarbons into said gas heated steam methane reforming reactor,
utilizing at least part of said first and/or second synthesis gas streams as heating media in heat exchange within said gas heated steam methane reforming reactor,
generating a third synthesis gas stream over the fourth catalyst within the gas heated steam methane reforming reactor, and
outputting said third synthesis gas stream from said reforming section as at least part of said combined synthesis gas.
13. The process according to claim 11 , wherein said reforming section furthermore comprises a gas heated steam methane reforming reactor in parallel to said electrically heated steam methane reforming reactor, said fired reforming reactor and said autothermal reforming reactor, wherein said gas heated steam methane reforming reactor comprises a fourth catalyst, said process furthermore comprising the steps of:
inletting a third part of the feed gas comprising hydrocarbons into said gas heated steam methane reforming reactor,
utilizing at least part of said auto-reformed synthesis gas stream as heating medium in heat exchange within said gas heated steam methane reforming reactor,
generating a third synthesis gas stream over the fourth catalyst within the gas heated steam methane reforming reactor, and
outputting said third synthesis gas stream from said reforming section as at least part of said combined synthesis gas.
14. The process according to claim 10 , wherein said post processing unit is a post conversion unit housing a fifth catalyst active for catalyzing steam methane reforming, methanation and reverse water gas shift reactions.
15. The process according to claim 10 , wherein said post processing unit is a water gas shift unit arranged to carry out water gas shift reaction.
16. The process according to claim 10 , wherein said electrical heating unit comprises a macroscopic structure of electrically conductive material, where said macroscopic structure supports a ceramic coating and said ceramic coating supports said catalytically active material.
17. The process according to claim 10 , wherein the first part of the feed gas is about 5-20 vol % of the feed gas.
18. The process according to claim 12 , wherein the first part of the feed gas is about 5-10 vol % of the feed gas and the third part of the feed gas is about 5-10 vol % of the feed gas.