Chemical plant with a reforming section and a process for producing a chemical product

Abstract

The invention relates to a chemical plant comprising a reforming section arranged to receive a feed gas comprising hydrocarbons and provide a synthesis gas, wherein the reforming section comprises: an electrically heated reforming reactor housing a first catalyst, said electrically heated reforming reactor being arranged for receiving said feed gas and generating a first synthesis gas; and an autothermal reforming reactor downstream said electrically heated reforming reactor, said autothermal reforming reactor housing a second catalyst, said autothermal reforming reactor being arranged for receiving said first synthesis gas and outputting a second synthesis gas, wherein said reforming section is arranged to output said output synthesis gas comprising said second synthesis gas. The invention also relates to a process for producing a chemical product from a feed gas comprising hydrocarbons, in a chemical plant according to the invention.

Claims

1. A chemical plant comprising: a reforming section arranged to receive a feed gas comprising hydrocarbons and provide an output synthesis gas, wherein said reforming section comprises: an electrically heated reforming reactor housing a first catalyst, said electrically heated reforming reactor being arranged for receiving said feed gas and generating a first synthesis gas, an autothermal reforming reactor downstream said electrically heated reforming reactor, said autothermal reforming reactor housing a second catalyst, said autothermal reforming reactor being arranged for receiving said first synthesis gas and outputting a second synthesis gas, wherein said reforming section is arranged to output said output synthesis gas comprising said second synthesis gas.

2. The chemical plant according to claim 1, wherein said electrically heated reforming reactor comprises: a pressure shell housing an electrical heating unit arranged to heat said first catalyst, where said first catalyst is operable to catalyzing steam reforming of said feed gas, wherein said pressure shell has a design pressure of between 5 and 90 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 450° C. by passing an electrical current through said electrical heating unit.

3. The chemical plant according to claim 2, 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 first catalyst.

4. The chemical plant according to claim 1, further comprising a prereformer upstream said electrically heated reforming reactor.

5. The chemical plant according to claim 1, wherein said reforming section furthermore comprises a gas heated steam methane reforming reactor in parallel to said electrically heated reforming reactor and said autothermal reforming reactor, wherein said gas heated steam methane reforming reactor comprises a third catalyst and being operable to receive a second feed gas comprising hydrocarbons and to utilize at least part of said second synthesis gas 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.

6. The chemical plant according to claim 1, further comprising: a post processing unit downstream the reforming section, where said post processing unit is arranged to receive said output synthesis gas and provide a post processed synthesis gas.

7. The chemical plant according to claim 6, wherein said post processing unit is a post conversion unit having an inlet for allowing addition of heated CO.sub.2 to said output synthesis gas upstream the post conversion unit and housing a fourth catalyst active for catalyzing steam methane reforming, methanation and reverse water gas shift.

8. The chemical plant according to claim 6, wherein said post processing unit is a water gas shift unit arranged to carry out the water gas shift reaction, thereby providing a post processed synthesis gas.

9. The chemical plant according to claim 1, further comprising: a first separation unit arranged to separate said output synthesis gas or said post processed synthesis gas into a water condensate and an intermediate synthesis gas.

10. The chemical plant according to claim 1, further comprising: a downstream section arranged to receive the intermediate synthesis gas and to process the intermediate synthesis gas to a chemical product and an off-gas.

11. The chemical plant according to claim 10, further comprising: a fired heater unit upstream said electrically heated reforming reactor, the fired heater unit being arranged to preheat the said feed gas, and means for recycling at least part of said off-gas from said downstream section as fuel to the fired heater unit.

12. The chemical plant according to any of the claims 11, wherein said downstream section comprises gas separation unit(s) arranged to separate a stream of substantially pure CO.sub.2, H.sub.2, and/or CO from said intermediate synthesis gas, thereby providing a refined synthesis gas.

13. The chemical plant according to claim 1, wherein said downstream section comprises an ammonia reactor to convert said intermediate synthesis gas or said refined synthesis gas to ammonia, a methanol reactor to convert said intermediate synthesis gas or said refined synthesis gas to methanol, or a Fischer-Tropsch reactor to convert said intermediate synthesis gas or said refined synthesis gas to a mixture of higher hydrocarbons.

14. The chemical plant according to claim 2, wherein the electrical power supply and the electrical heating unit within the pressure shell are dimensioned so that at least part of the electrical heating unit reaches a temperature of 450° C.-850° C.

15. A process for producing a chemical product from a feed gas comprising hydrocarbons, in a chemical plant comprising a reforming section, said reforming section comprising an electrically heated reforming reactor housing a first catalyst, and an autothermal reforming reactor downstream said electrically heated reforming reactor, said autothermal reforming reactor housing a second catalyst, said process comprising the steps of: inletting said feed gas to said electrically heated reforming reactor and carrying out steam methane reforming to provide a first synthesis gas, inletting said first synthesis gas to said autothermal reforming reactor, and carrying out steam methane reforming to provide a second synthesis gas, outputting a synthesis gas comprising said second synthesis gas from said reforming section.

16. The process according to claim 15, wherein said electrically heated reforming reactor comprises a pressure shell housing an electrical heating unit arranged to heat said first catalyst, wherein said first catalyst is operable to catalyze steam reforming of said feed gas, wherein said pressure shell has a design pressure of between 5 and 90 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 process further comprises the steps of: pressurizing said feed gas to a pressure of between 5 and 90 bar upstream said electrically heated 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 450° C.

17. The process according to claim 15, further comprising the step of adding one or more additional feed streams to the reforming section upstream the electrically heated reformer, to the first synthesis gas, and/or directly to the autothermal reforming reactor.

18. The process according to claim 17, wherein a tail gas from a Fischer-Tropsch unit is added to the first synthesis gas or directly to the autothermal reforming reactor.

19. The process according to claim 15, further comprising the step of prereforming said feed gas in a prereformer upstream said electrically heated reforming reactor.

20. The process according to claim 15, wherein said reforming section furthermore comprises a gas heated steam methane reforming reactor in parallel to said electrically heated reforming reactor and said autothermal reforming reactor, wherein said gas heated steam methane reforming reactor comprises a third catalyst, said process furthermore comprising the steps of: inletting a second feed comprising hydrocarbons into said gas heated steam methane reforming reactor, utilizing at least part of said second synthesis gas as heating media in heat exchange within said gas heated steam methane reforming reactor, generating a third synthesis gas over the third catalyst within the gas heated steam methane reforming reactor, and outputting said third synthesis gas from said reforming section as at least part of said output synthesis gas.

21. The process according to claim 15, further comprising: in a post processing unit downstream said reforming section, post processing said output synthesis gas to provide a post processed synthesis gas.

22. The process according to claim 21, wherein said post processing unit is a post conversion unit housing a fourth catalyst active for catalyzing steam methane reforming, methanation and reverse water gas shift reactions, wherein said process furthermore comprises the step of inletting heated CO.sub.2 to said output synthesis gas upstream said post conversion unit.

23. The process according to claim 21, wherein said post processing unit is a water gas shift unit and the step of post processing said output synthesis gas comprises carrying out the water gas shift reaction.

24. The process according to claim 15, further comprising the step of: separating said output synthesis gas or said post processed synthesis gas into a water condensate and an intermediate synthesis gas in a first separation unit downstream said post processing unit.

25. The process according to claim 15, further comprising the step of: providing said intermediate synthesis gas to a downstream section arranged to receive the intermediate synthesis gas and to process the intermediate synthesis gas to said chemical product and an off-gas.

26. The process according to claim 25, further comprising: providing fuel to a fired heater unit upstream said autothermal reforming reactor, said fired heater unit being operable to preheat said feed gas, and recycling at least part of said off-gas from said downstream section as fuel to the fired heater unit.

27. The process according to claim 15, wherein said process comprises separating a stream of substantially pure CO.sub.2, H.sub.2, and/or CO from said intermediate synthesis gas, thereby providing a refined synthesis gas, in one or more gas separation unit(s) of said downstream section.

28. The process according to claim 15, wherein said process further comprises: converting said intermediate synthesis gas to ammonia in an ammonia reactor of said downstream section, to convert said intermediate synthesis gas to methanol in a methanol reactor of said downstream section, or to convert said intermediate synthesis gas to a mixture of higher hydrocarbons in a Fischer-Tropsch reactor.

Description

SHORT DESCRIPTION OF THE FIGURES

[0094] FIG. 1 shows a chemical plant according to an embodiment of the invention, where the reforming section comprises an electrically heated reforming reactor and an autothermal reactor in series;

[0095] FIG. 2 shows a chemical plant according to an embodiment of the invention, where the reforming section comprises an electrically heated reforming reactor, an autothermal reactor and a gas heated steam methane reforming reactor;

[0096] FIGS. 3 and 4 show chemical plants according to embodiments of the invention, comprising a downstream section and recycling of an off-gas.

DETAILED DESCRIPTION OF THE FIGURES

[0097] FIG. 1 shows a chemical plant 100 according to an embodiment of the invention. The chemical plant 100 is a synthesis gas plant comprising a reforming section 110 with an electrically heated reforming reactor 108 housing a first catalyst and an autothermal reforming reactor 109 housing a second catalyst. The electrically heated reforming reactor 108 and autothermal reforming reactor 109 are arranged in series within the reforming section 110. The electrically heated reforming reactor 108 is arranged to receiving a feed gas 25′, and to generate a first synthesis gas 26. The autothermal reforming reactor 109 is arranged to receive the first synthesis gas 26 as well as a stream 27 of oxidant gas. The stream 27 of oxidant gas comprises oxygen and may be e.g. air or oxygen, or a mixture of more than 90% oxygen with the balance being e.g nitrogen, steam and/or argon.

[0098] During operation of the chemical plant 100, a feed gas 21 comprising hydrocarbons undergoes feed purification in a desulfurization unit 101 and becomes a desulfurized feed gas 22. The feed gas 21 comprising hydrocarbons is e.g. natural gas or town gas. The desulfurized feed gas 22 is preheated in a fired heater unit 105 and steam 23 is added, resulting in a gas stream 24. The gas stream 24 is led to a prereforming unit 102 housing steam reforming catalyst. Typically, the prereforming unit 102 is an adiabatic prereforming unit, wherein higher hydrocarbons are reacted so that the prereformed feed gas 25 exiting the prereformer contains no or very small amounts of higher hydrocarbons. The prereformed feed gas 25 is heated in the fired heater unit 105 to a heated prereformed feed gas 25′, which is led to the electrically heated reforming reactor 108

[0099] The heated prereformed feed gas 25′ undergoes steam methane reforming in the electrically heated reforming reactor 108, and a first synthesis gas 26 is output from the electrically heated reforming reactor 108. The first synthesis gas 26 is input to the autothermal reforming reactor 109, wherein it undergoes partial combustion together with by sub-stoichiometric amounts of oxygen from the stream 27, followed by steam reforming of the partially combusted hydrocarbon feed gas in a fixed bed of the second catalyst. The second catalyst is a steam methane reforming catalyst. A resulting second synthesis gas 30 is output from the autothermal reforming reactor 109. The second synthesis gas 30 is output from the reforming section as the output synthesis gas.

[0100] The electrically heated reforming reactor 108 e.g. comprises a pressure shell housing an electrical heating unit 108′ arranged to heat the first catalyst. The first catalyst is operable to catalyzing steam reforming of the feed gas. The pressure shell has a design pressure of between 5 and 45 bar. A heat insulation layer may be adjacent to at least part of the inside of said pressure shell. At least two conductors are electrically connected to the electrical heating unit and to an electrical power supply 107 is placed outside the pressure shell. The electrical power supply 107 is dimensioned to heat at least part of the first catalyst to a temperature of at least 500° C. by passing an electrical current through the electrical heating unit.

[0101] The output synthesis gas 30 is cooled in a heat exchanger 111 to a cooled synthesis gas 30′. The cooled synthesis gas 30′ enters a post processing unit 113, e.g. a water gas shift unit, and a water gas shifted synthesis gas 32 exits the water gas shift unit 113. The water gas shifted synthesis gas 32 is cooled in a second heat exchanger 114 to a cooled water gas shifted synthesis gas 32′, which enters the first separation unit 115. The first separation unit 115 e.g. comprises a flash separation unit. The cooled water gas shifted synthesis gas 32′ thus enters the flash separation unit 115 arranged to separate the cooled water gas shifted synthesis gas 32′ into water 29 and an intermediate synthesis gas 34, viz. a dry synthesis gas. Optionally, the intermediate synthesis gas 34 may enter a PSA unit (not shown in FIG. 1) arranged to separate the intermediate synthesis gas 34 into a product synthesis gas in the form of a stream of substantially pure hydrogen and an off-gas. A heat exchange fluid 20, such as water, is used for heat exchange in the heat exchanger 111 and a heated heat exchange fluid, such as steam, is exported as stream 20′.

[0102] It should be noted, that the chemical plant 100 typically comprises further equipment, such as compressors, heat exchangers etc.; however, such further equipment is not shown in FIG. 1. Moreover, it should be noted that even though FIG. 1 shows a purification unit in the form of a desulfurization unit 101 and a prereforming unit 102, such units need not be part of the chemical plant 100.

[0103] FIG. 2 shows a chemical plant 200 according to an embodiment of the invention. The chemical plant 200 is a synthesis gas plant comprising a reforming section 210 with an electrically heated reforming reactor 108 housing a first catalyst, an autothermal reforming reactor 109 housing a second catalyst and a gas heated steam methane reforming reactor 112 housing a third catalyst. The electrically heated reforming reactor 108 and autothermal reforming reactor 109 are arranged in series within the reforming section 210. The electrically heated reforming reactor 108 is arranged to receive a feed gas 25′, and to generate a first synthesis gas 26. The autothermal reforming reactor 109 is arranged to receive the first synthesis gas 26 as well as a stream 27 of oxidant gas and to generate a second synthesis gas 28. The stream 27 of oxidant gas comprises oxygen and may be e.g. air or oxygen, or a mixture of more than 90% oxygen with the balance being e.g nitrogen, steam, and/or argon.

[0104] During operation of the chemical plant 100, a feed gas 21 comprising hydrocarbons undergoes feed purification in a desulfurization unit 101 and becomes a desulfurized feed gas 22. The feed gas 21 comprising hydrocarbons is e.g. natural gas or town gas. The desulfurized feed gas 22 is preheated in a fired heater unit 105 and steam 23 is added, resulting in a gas stream 24. The gas stream 24 is led to a prereforming unit 102 housing steam reforming catalyst. Typically, the prereforming unit 102 is an adiabatic prereforming unit, wherein higher hydrocarbons are reacted so that the prereformed feed gas 25 exiting the prereformer contains no or very small amounts of higher hydrocarbons. The prereformed feed gas 25 is heated in the fired heater unit 105 to a heated prereformed feed gas 25′, which is led to the electrically heated reforming reactor 108.

[0105] A fuel gas 46 comprising hydrocarbons, e.g. natural gas, to is sent to the fired heater unit in order to be burned off to provide heat within the fired heater unit 105. An effluent gas 48 is output from the fired heater unit 105.

[0106] A first part 25a of the heated prereformed feed gas 25′ undergoes steam methane reforming in the electrically heated reforming reactor 108, and a first synthesis gas 26 is output from the electrically heated reforming reactor 108. The first synthesis gas 26 is input to the autothermal reforming reactor 109, wherein it undergoes partial combustion together with by sub-stoichiometric amounts of oxygen from the stream 27, followed by steam reforming of the partially combusted hydrocarbon feed gas in a fixed bed of the second catalyst. The second catalyst is a steam reforming catalyst. A resulting second synthesis gas 30 is output from the autothermal reforming reactor 109.

[0107] The second synthesis gas 28 is inlet to the gas heated steam methane reforming reactor 112 in order to provide heat for the steam methane reforming reaction of the second part 25b of the feed gas 25 entering the gas heated steam methane reforming reactor 112 from another side. The gas exiting the gas heated steam methane reforming reactor 112 is a third synthesis gas 30. The third synthesis gas 30 is the output synthesis gas output from the reforming section.

[0108] The output synthesis gas 30 is cooled in a heat exchanger 111 to a cooled synthesis gas 30′. The cooled synthesis gas 30′ enters a post processing unit 113, e.g. a water gas shift unit, and a water gas shifted synthesis gas 32 exits the water gas shift unit 113. The water gas shifted synthesis gas 32 is cooled in a second heat exchanger 114 to a cooled water gas shifted synthesis gas 32′, which enters the first separation unit 115. The first separation unit 115 e.g. comprises a flash separation unit. The cooled water gas shifted synthesis gas 32′ thus enters the flash separation unit 115 arranged to separate the cooled water gas shifted synthesis gas 32′ into water 29 and an intermediate synthesis gas 34, viz. a dry synthesis gas. Optionally, the intermediate synthesis gas 34 may enter a PSA unit (not shown in FIG. 1) arranged to separate the intermediate synthesis gas 34 into a product synthesis gas in the form of a stream of substantially pure hydrogen and an off-gas. A heat exchange fluid 20, such as water, is used for heat exchange in the heat exchanger 111 and a heated heat exchange fluid, such as steam, is exported as stream 20′.

[0109] It should be noted, that the chemical plant 100 typically comprises further equipment, such as compressors, heat exchangers etc.; however, such further equipment is not shown in FIG. 1. Moreover, it should be noted that even though FIG. 1 shows a purification unit in the form of a desulfurization unit 101 and a prereforming unit 102, such units need not be part of the chemical plant 100.

[0110] FIG. 3 shows a chemical plant according to embodiments of the invention, comprising a downstream section and recycling of an off-gas. Thus, FIG. 3 includes the units of the chemical plant shown in FIG. 1 in addition to further units. The parts that are the same for FIGS. 1 and 3 will not be described in detail below.

[0111] The chemical plant 300 of FIG. 3 thus includes the desulfurization unit 101, the prereforming unit 102, the fired heater unit 105, the reforming section 110, the post processing unit 113, the first separation unit 115, and the heat exchangers 111 and 114 as described in relation to FIG. 1.

[0112] The output synthesis gas 30 exiting from the reforming section 110 is cooled in the heat exchanger 111 to a cooled synthesis gas 30′. The cooled synthesis gas 30′ enters the post processing unit 113, here in the form of a water gas shift unit, and a water gas shifted synthesis gas 32 exits the water gas shift unit 113. The water gas shifted synthesis gas 32 is cooled in a second heat exchanger 114 to a cooled water gas shifted synthesis gas 32′, which enters the first separation unit 115, such as e.g. a flash separation unit 115 arranged to separate the cooled water gas shifted synthesis gas 32′ into a condensate 29 and an intermediate synthesis gas 34, viz. a dry synthesis gas. The intermediate synthesis gas 34 enters the downstream section 116 arranged to process the intermediate synthesis gas 34 to a chemical product 40 and an off-gas 45. The downstream section 116 comprises e.g. an ammonia reactor to convert the intermediate synthesis gas 34 to ammonia, a methanol reactor to convert the intermediate synthesis gas 34 gas to methanol, or a Fischer-Tropsch reactor to convert the intermediate synthesis gas 34 to a mixture of higher hydrocarbons.

[0113] The off-gas 45 from the downstream section 116 is recycled as fuel to one or more burners of the fired heater unit 105. The off-gas 45 is combined with a small amount of make-up gas 46 comprising hydrocarbons, e.g. natural gas, to form the fuel gas 47 sent to the one or more burners of the fired heater unit 105. The fired heater unit 105 is arranged to provide heat for preheating the feed gas 21, the desulfurized feed gas 22, and the prereformed feed gas 25. An effluent gas 48 is output from the fired heater unit 105.

[0114] A fuel gas 46 comprising hydrocarbons, e.g. natural gas, to is sent to the fired heater unit in order to be burned off to provide heat within the fired heater unit 105. An effluent gas 48 is output from the fired heater unit 105.

[0115] A heat exchange fluid 20, such as water, is used for heat exchange in the heat exchanger 111 and a heated heat exchange fluid, such as steam, is exported as stream 20′. A part of the steam is used as addition of steam 23 to the desulfurized feed gas 22.

[0116] By recycling off-gas from the downstream section 116 back to the fired heater unit 105, it is rendered possible to maximize the use of hydrocarbons in the feed on the process side and minimize the use of natural gas within the fired heater unit 105. It is possible to balance the chemical plant so that the operation of the fired heater unit 105 is adjusted to being primarily, or even fully, driven by heat supplied by burning a recycled off-gas 45. This allows for a minimum use of natural gas imported for being burned off for heat in the chemical plant 300, which in turn allows for an optimal utilization of feed gasses comprising hydrocarbons to the chemical plant. Typically, a relatively small amount of make-up gas 46 comprising hydrocarbons, e.g. natural gas, is also fed to the fired heater unit 105 in order to allow for control of the duty of the fired heater unit. The term “duty” is in this context understood as the heat input added to or removed from a unit operation in a chemical plant.

[0117] FIG. 4 shows a chemical plant 400 according to an embodiment of the invention, comprising a downstream section and recycling of an off-gas. FIG. 4 includes the units of the chemical plants shown in FIG. 2, in addition to further units. The parts that are the same for FIGS. 2 and 4 will not be described in detail below.

[0118] The chemical plant 300 of FIG. 3 thus includes the desulfurization unit 101, the prereforming unit 102, the fired heater unit 105, the reforming section 210, the post processing unit 113, the first separation unit 115, and the heat exchangers 111 and 114 as described in relation to FIG. 2.

[0119] The output synthesis gas 30 exiting from the reforming section 210 is cooled in the heat exchanger 111 to a cooled synthesis gas 30′. The cooled synthesis gas 30′ enters the post processing unit 113, here in the form of a water gas shift unit, and a water gas shifted synthesis gas 32 exits the water gas shift unit 113. The water gas shifted synthesis gas 32 is cooled in a second heat exchanger 114 to a cooled water gas shifted synthesis gas 32′, which enters the first separation unit 115, such as e.g. a flash separation unit 115 arranged to separate the cooled water gas shifted synthesis gas 32′ into a condensate 29 and an intermediate synthesis gas 34, viz. a dry synthesis gas. The intermediate synthesis gas 34 enters the downstream section 116 arranged to process the intermediate synthesis gas 34 to a chemical product 40 and an off-gas 45. The downstream section 116 comprises e.g. an ammonia reactor to convert the intermediate synthesis gas 34 to ammonia, a methanol reactor to convert the intermediate synthesis gas 34 gas to methanol, or a Fischer-Tropsch reactor to convert the intermediate synthesis gas 34 to a mixture of higher hydrocarbons.

[0120] The off-gas 45 from the downstream section 116 is recycled as fuel to one or more burners of the fired heater unit 105. The off-gas 45 is combined with a small amount of make-up gas 46 comprising hydrocarbons, e.g. natural gas, to form the fuel gas 47 sent to the one or more burners of the fired heater unit 105. The fired heater unit 105 is arranged to provide heat for preheating the feed gas 21, the desulfurized feed gas 22, and the prereformed feed gas 25.

[0121] A heat exchange fluid 20, such as water, is used for heat exchange in the heat exchanger 111 and a heated heat exchange fluid, such as steam, is exported as stream 20′. A part of the steam is used as addition of steam 23 to the desulfurized feed gas 22.

[0122] By recycling off-gas from the downstream section 116 back to the fired heater unit 105, it is rendered possible to maximize the use of hydrocarbons in the feed on the process side and minimize the use of natural gas within the fired heater unit 105. It is possible to balance the chemical plant so that the operation of the fired heater unit 105 is adjusted to being primarily, or even fully, driven by heat supplied by burning a recycled off-gas 45. This allows for a minimum use of natural gas imported for being burned off for heat in the chemical plant 300, which in turn allows for an optimal utilization of feed gasses comprising hydrocarbons to the chemical plant. Typically, a relatively small amount of make-up gas 46 comprising hydrocarbons, e.g. natural gas, is also fed to the fired heater unit 105 in order to allow for control of the duty of the fired heater unit 105. The term “duty” is in this context understood as the heat input added to or removed from a unit operation in a chemical plant.

[0123] The embodiments shown in FIGS. 1 to 4 all show a feed gas entering into the electrically heated reforming reactor from the lower side of the electrically heated reforming reactor. It is understood that this is not necessarily the case and that the feed gas may enter the electrically heated reforming reactor from the top or the side, if appropriate.

[0124] It should be noted, that the chemical plants shown in FIGS. 1 to 4 typically comprise further equipment, such as compressors, heat exchangers etc.; however, such further equipment is not shown in the figures.

EXAMPLE

[0125] In the classical 2-step reforming methanol layout (2-step-MeOH), the chemical plant comprises a reforming section with a primary reformer in the form of a steam methane reformer (SMR) and a methanol section. Natural gas is used as the principal reformer feed and is prereformed and fed to the primary reformer. Heating of the SMR is provided by natural gas in some part and expanded off-gas from the methanol (MeOH) synthesis which comes in part from the MeOH loop and the MeOH distillation. The partially reformed gas from the primary reformer is sent to a secondary reformer which is supplied with oxygen, typically from an air separation unit (ASU), where oxygen addition is controlled in order to obtain the desired module of the synthesis gas. The synthesis gas from the reforming section is cooled to remove water in the process gas, before it is compressed to 92 barg. The compressor was driven by a steam turbine, operated on superheated steam produced in the waste-heat section of the SMR. The compressed synthesis gas was combined with recycle gas from the methanol loop and sent to the methanol reactor of the methanol section and the resulting product was refined to a final pure methanol product.

[0126] In this example, a 2-step reforming methanol layout (2-step-MeOH) as described above is compared with an electrically heated reformer (2-step eSMR-MeOH). Making a 2-step reforming layout with an electrically heated reformer (eSMR) was done by also including a fired heater for feed preheating; the fired heater was fueled partly by expanded off-gas from the methanol section and natural gas. In this specific case, additional burning of natural gas was required to provide sufficient superheated steam to drive the turbine(s).

[0127] Comparing consumption figures of the two layouts is shown in Table 1. Using an electrically heated reformer (eSMR) in the 2-step reforming layout in 2-step-eSMR-MeOH was found to have the same feed consumption as the classical 2-step-MeOH layout. However, a large difference is found on the fuel side, where the majority of the natural gas consumption was replaced with electricity. This, obviously, translate into lower CO.sub.2 emissions from the 2-step-eSMR-MeOH layout, which is associated with the reduced flue gas emissions.

TABLE-US-00001 TABLE 1 2-step- 2-step- eSMR- MeOH MeOH Consumption: Natural gas feed[ kNm.sup.3/h] 146.6 146.6 Natural gas fuel [Nm.sup.3/h] 20.6 2.7 Electricity work [MW] 39.2 213.9 Production: MeOH product MTPD 5000 5000 CO.sub.2 emissions (plant) [kNm.sup.3/h] 28.6 11.6