Low carbon intensity methanol production

Abstract

This invention relates to a methanol plant and a method for producing methanol, wherein a combination of a high-temperature shift (HTS) section and a steam superheater enables the output of a superheated steam stream, which can be used to heat or preheat other sections or streams in the plant / method. This reduces or eliminates the need for feed preheating and steam superheating via combustion heaters.

Description

Technical Field

[0001] This invention relates to a methanol plant and a method for producing methanol, wherein a combination of a high-temperature shift (HTS) section and a steam superheater enables the output of a superheated steam stream, which can be used to heat or preheat other sections or streams in the plant / method. This reduces or eliminates the need for feed preheating and steam superheating via combustion heaters. Background Technology

[0002] In a typical syngas generation unit based on oxygen combustion reforming, feed preheating and steam superheating for the turbine are achieved by a combustion heater through the combustion of various exhaust gases and natural gas. The majority of the superheated steam is used to drive the turbine, which powers the large compressor in the unit.

[0003] To reduce CO2 emissions (i.e., carbon intensity) per unit of methanol production, as described in (WO 2022 / 248434), hydrogen-rich fuels can be used to replace carbon-containing fuels, thereby producing a CO2-rich output stream for sequestration. In some geographic locations, sequestration is not feasible; therefore, a layout without any combustion heaters would be attractive for producing methanol with low carbon intensity.

[0004] Therefore, it is necessary to reduce the carbon intensity of methanol production and find solutions to reduce or avoid the use of combustion heaters. Summary of the Invention

[0005] ATR-based methanol production methods emit CO2 into the atmosphere by burning carbonaceous fuel in a combustion heater for preheating purposes. The carbon intensity (CO2 emissions per ton of methanol produced) of such methods is approximately 0.3 tons of CO2 per ton of methanol produced.

[0006] It has been found that eliminating the combustion heater by using a combination of renewable energy and alternative preheating configurations can significantly reduce the carbon intensity of methanol production. Furthermore, the method of this invention does not produce a CO2-rich output stream, making it particularly suitable for methanol plants located in areas where CO2 storage or CO2 distribution infrastructure is infeasible or unavailable.

[0007] In this technology, the syngas sidestream generated in the ATR, drawn from downstream of the WHB, is fed into the high-temperature shift reactor (HTS). Since the shift reaction is exothermic, the effluent can be used to superheat the steam generated upstream in the WHB. A portion of the superheated steam is used to preheat the feed to the pre-reformer, and then the feed to the desulfurization section. De-superheated steam is introduced upstream of the HTS to achieve the required steam / dry gas ratio for the HTS catalyst.

[0008] Feed preheating to the ATR can be eliminated because, during normal operation, the ATR can run directly on the pre-reformer effluent at the expense of higher oxygen consumption. For startup, an external heating source (such as a start-up electric heater) will be required to reach the ATR's ignition temperature. Since most of the superheated steam is used for preheating, the main compressor will likely require electric drive. If the electricity comes from a renewable source, the carbon intensity of the methanol products will be reduced. Purge gas from methanol synthesis can be partially recycled to the ATR before being used as fuel to reduce carbon-rich stream emissions to the OSBL while balancing the fuel requirements of the plant's auxiliary boilers. Tail gas from distillation can also be sent to the same location.

[0009] A methanol processing device is provided. The methanol processing device includes: - Hydrocarbon feed; - Water feed; - Oxygen feed; - A feed preheater, which is arranged to preheat the hydrocarbon feed by exchanging heat with at least a portion of a second superheated steam stream, and output the preheated hydrocarbon feed and a third superheated steam stream; - A purification section, which is arranged to remove sulfur compounds from the preheated hydrocarbon feed and output purified hydrocarbon feed. - A pre-reformer feed preheater, which is arranged to heat the purified hydrocarbon feed and output the heated purified hydrocarbon feed. - A pre-reforming section, which is arranged to pre-reform heated and purified hydrocarbon feed from the pre-reforming feed preheater in the presence of at least a portion of the superheated steam flow from the steam superheater, and output a first synthesis gas stream; - A self-heating reforming section, which is arranged to receive at least a portion of the first synthesis gas stream from the pre-reforming section and the oxygen feed, and output a second synthesis gas stream; - A steam generation section, which is arranged to allow at least a portion of the second synthesis gas stream to exchange heat with the water feed, and to generate a third synthesis gas stream and a first steam stream; - A methanol synthesis section, which is arranged to receive a first portion of a third synthesis gas stream and at least a portion of a fifth synthesis gas stream to generate a crude methanol stream, a first tail gas stream, and a second tail gas stream; - High Temperature Shift (HTS) section, which is arranged to receive a second portion of the third synthesis gas stream and a portion of the third superheated steam stream, and generate a fourth synthesis gas stream; - A steam superheater, which is arranged to superheat at least a portion of the first steam stream from the steam generation section by exchanging heat with at least a portion of the fourth synthesis gas stream from the HTS section; and outputs a first superheated steam stream and a fifth synthesis gas stream; The pre-reformer feed preheater is arranged to heat the hydrocarbon feed by exchanging heat with at least a portion of a first superheated steam stream from a steam superheater, and outputs a second superheated steam stream.

[0010] A method for producing methanol in the methanol plant described herein is also provided. The method includes the following steps: a. To provide a methanol apparatus according to any one of the preceding claims, b. In the feed preheater, the hydrocarbon feed is heated by heat exchange with at least a portion of the second superheated steam stream, and the preheated hydrocarbon feed and the third superheated steam stream are output; c. In the purification section, sulfur compounds are removed from the preheated hydrocarbon feed, and the purified hydrocarbon feed is output. d. The purified hydrocarbon feed is heated in the pre-reformer feed preheater, and the heated purified hydrocarbon feed is output. e. In the pre-reforming section, heated and purified hydrocarbon feed from the pre-reforming unit feed preheater is pre-reformed in the presence of at least a portion of the superheated steam from the steam superheater, and a first synthesis gas stream is output. f. In the self-heating reforming section, at least a portion of the first synthesis gas stream from the pre-reforming section and the oxygen feed are reformed, and a second synthesis gas stream is output; g. In the steam generation section, at least a portion of the second synthesis gas stream is subjected to heat exchange with the water feed to generate a third synthesis gas stream and a first steam stream; h. Feed the first portion of the third synthesis gas stream and at least a portion of the fifth synthesis gas stream into the methanol synthesis section to generate a crude methanol stream, a first tail gas stream, and a second tail gas stream; i. A second portion of the third synthesis gas stream and a portion of the third superheated steam stream are fed into the high-temperature shift converter (HTS) section to generate a fourth synthesis gas stream; j. In a steam superheater, at least a portion of the first steam stream from the steam generation section is superheated by exchanging heat with at least a portion of the fourth synthesis gas stream output from the HTS section; and the first superheated steam stream and the fifth synthesis gas stream are output; The step of heating the hydrocarbon feed in the pre-reformer feed preheater is carried out by heat exchange with at least a portion of the first superheated steam stream output from the steam superheater, thereby outputting a second superheated steam stream.

[0011] Further details of the invention will be set forth in the following description, drawings, aspects and dependent claims. Attached Figure Description

[0012] This technology is illustrated by the following diagram, in which: Figure 1The layout of the methanol equipment / method of the present invention is described. Invention Details

[0014] Unless otherwise specified, all gas percentages given are by volume. All feeds are preheated as required.

[0015] A “segment” contains one or more “units” that perform changes to the chemical composition of the feed, and may additionally include elements such as heat exchangers, mixers or compressors that do not change the chemical composition of the feed or stream.

[0016] The term "synthesis gas" (abbreviated as "syngas") refers to a gas containing hydrogen, carbon monoxide, carbon dioxide, steam, and small amounts of other gases (such as argon, nitrogen, methane, etc.).

[0017] As described above, a methanol equipment is provided.

[0018] A hydrocarbon feedstock is provided. This hydrocarbon feedstock suitably contains a predominantly methane component, for example, more than 80%, or even more than 90% methane. Higher hydrocarbons (having >2 carbon atoms) may also be present. Suitably, the hydrocarbon feedstock is a natural gas feedstock. The hydrocarbon feedstock may also contain small amounts of argon, nitrogen, carbon dioxide, steam, and sulfides.

[0019] A water feed is provided. This water feed suitably contains a major portion of water, for example, more than 99% water. Suitably, the water feed is desalinated and deaerated.

[0020] An oxygen feed is provided. This oxygen feed is suitably "oxygen-enriched," meaning that the majority of the feed is O2; that is, more than 75%, such as more than 90%, or more than 95%, such as more than 99%, of the feed is O2. The oxygen feed may also contain other components, such as nitrogen, argon, CO2, and / or steam. The oxygen feed will typically contain a small amount of steam (e.g., 5-10%). Steam can be added to the oxygen feed upstream of the ATR section.

[0021] The feed preheater is arranged to preheat the hydrocarbon feed by exchanging heat with at least a portion of a second superheated steam stream (see below), and outputs the preheated hydrocarbon feed and a third superheated steam stream. In other words, the second superheated steam stream provides heat to the hydrocarbon feed, thereby reducing its temperature to provide the third superheated steam stream. At the inlet of the HTS section, the temperature of the third superheated steam stream is suitably 270-330°C.

[0022] The purification section is arranged to remove sulfur compounds from the preheated hydrocarbon feed and output purified hydrocarbon feed. Sulfur may be present in the hydrocarbon feed in the form of sulfides; however, the presence of sulfur in the stream entering the (pre)reforming section is undesirable because its presence typically leads to catalyst contamination, such as the formation of carbon on the catalyst surface. Suitable purification sections (e.g., hydrodesulfurization sections) are well known to those skilled in the art.

[0023] The pre-reformer feed preheater is configured to heat the purified hydrocarbon feed and output the heated purified hydrocarbon feed. The pre-reformer feed preheater is also configured to heat the hydrocarbon feed by exchanging heat with at least a portion of a first superheated steam stream (see below) from a steam superheater and output a second superheated steam stream. At this point, the temperature of the heated purified hydrocarbon feed output from the pre-reformer feed preheater is between 390 and 420°C.

[0024] The pre-reforming section is arranged to pre-reform heated and purified hydrocarbon feed from the pre-reforming unit feed preheater in the presence of at least a portion of superheated steam from the steam superheater, and outputs a first synthesis gas stream. Pre-reforming is a process in which methane and heavier hydrocarbons are steam-reformed, and the products of the heavier hydrocarbon reforming are methanated. The pre-reforming section may include an adiabatic pre-reforming unit packed with a catalyst having a high nickel content. The adiabatic pre-reforming unit is typically located upstream of the main steam reformer. The provided first synthesis gas stream contains CO2, CH4, H2O, and H2, as well as typically smaller amounts of CO and possibly other components.

[0025] The autothermal reforming (ATR) section is arranged to receive at least a portion of the first synthesis gas stream from the pre-reforming section along with the oxygen feed, and to output a second synthesis gas stream. The ATR section may include one or more ATR reactors. An ATR reactor typically includes a burner, a combustion chamber, and a catalyst bed housed within a refractory-lined pressure vessel. In the ATR reactor, following localized combustion of hydrocarbons with a substoichiometric amount of oxidant (such as oxygen), steam reforming of the hydrocarbons with localized combustion occurs in a fixed bed of steam reforming catalyst (reactions 1 and 2).

[0026] CH4 (g) + H2O (g) CO (g) + 3H2 (g) (1)

[0027] CH4 (g) + 2H2O (g) CO2 (g) + 4H2(g) (2)

[0028] Due to the high temperature, steam reforming also occurs to some extent within the combustion chamber. The steam reforming reaction is accompanied by the water-gas shift reaction. Typically, at the reactor outlet, the gas is at or near equilibrium with respect to the steam reforming and water-gas shift reactions. More details and a complete description of ATR can be found in existing technologies, such as " Studies in Surface Science and Catalysis " , Vol. 152, “ Synthesis gas production for FT synthesis ";Chapter 4, p.258-352, 2004.

[0029] The second synthesis gas stream typically contains hydrogen, carbon monoxide, carbon dioxide, and steam. Other components, such as methane, nitrogen, and argon, may also be present, usually in small amounts. The operating pressure of the ATR stage will be between 5 and 100 bar, or more preferably between 15 and 60 bar.

[0030] Typically, the temperature of the second synthesis gas stream from the ATR section is 900-1100°C. This heat can be advantageously used elsewhere in the equipment. Therefore, the steam generation section is arranged to allow at least a portion of the second synthesis gas stream to exchange heat with the water feed, and to generate a third synthesis gas stream and a first steam stream.

[0031] The methanol synthesis section is arranged to receive at least a portion of the third synthesis gas stream and at least a portion of the fifth synthesis gas stream to generate a crude methanol stream, a first tail gas stream, and a second tail gas stream.

[0032] The high-temperature conversion (HTS) section is arranged to receive a second portion of the third synthesis gas stream and a portion of the third superheated steam stream, and to generate a fourth synthesis gas stream.

[0033] In a preferred aspect, the HTS section may include a promoting high-temperature shift catalyst based on zinc-aluminum oxide. In this aspect, when the device is operating, the steam-to-carbon ratio in the reforming and HTS sections is less than 2.6. The advantage of a low steam-to-carbon ratio in the reforming and shift sections compared to a high steam-to-carbon ratio is that it enables a higher syngas throughput. Furthermore, due to the lower total mass flow rate through the device, a low steam-to-carbon ratio requires smaller equipment at the front end.

[0034] In a preferred aspect, the temperature in the HTS section is in the range of 300 to 600°C, for example, 300 to 400°C, or for example, 340 to 380°C.

[0035] The steam superheater is arranged to superheat at least a portion of the first steam stream from the steam generation section by exchanging heat with at least a portion of the fourth synthesis gas stream from the HTS section; and outputs a first superheated steam stream and a fifth synthesis gas stream. The pre-reformer feed preheater (as described above) is arranged to heat the hydrocarbon feed by exchanging heat with at least a portion of the first superheated steam stream from the steam superheater, and outputs a second superheated steam stream.

[0036] Depending on the natural gas feed, autothermal reforming for methanol formation will often be substoichiometric, i.e., M < 2, and therefore requires the addition of hydrogen. In conventional ATR units employing a combustion heater, the purge gas and tail gas are used as fuel after hydrogen removal, eliminating the need for externally sourced equilibrium hydrogen. However, in the absence of a combustion heater, externally sourced hydrogen is likely required. Therefore, in one aspect, methanol plants also include a hydrogen feed arranged to be fed into the methanol synthesis section, preferably mixed with a first portion of the third synthesis gas stream.

[0037] Suitablely, the methanol plant also includes an electrolysis section arranged to provide the hydrogen feed. Preferably, the electrolysis section is arranged to be powered by renewable energy sources such as solar or wind power.

[0038] On one hand, the methanol plant also includes an electric steam methane reformer (e-SMR) arranged to produce hydrogen feed in the form of hydrogen-rich syngas, preferably wherein the hydrogen-rich syngas is arranged to superheat a third superheated steam stream.

[0039] Advantageously, at least a first portion of the first tail gas stream can be arranged to recirculate from the methanol synthesis section to the autothermal reforming section. The methanol plant may also include a tail gas recirculation compressor arranged to compress at least a portion of the second tail gas stream from the methanol synthesis section and recirculate the compressed second tail gas stream to the autothermal reforming section.

[0040] A methanol distillation section is typically installed to receive the crude methanol stream and output a purified methanol stream and a third tail gas stream.

[0041] On one hand, at least a portion of the third tail gas flow is arranged to be recirculated to the autothermal reforming section. This can improve the carbon utilization rate of the equipment.

[0042] A method for producing methanol in the methanol plant described herein is provided. The method includes the following steps: a. Provide the methanol equipment as defined herein. b. In the feed preheater, the hydrocarbon feed is heated by heat exchange with at least a portion of the second superheated steam stream, and the preheated hydrocarbon feed and the third superheated steam stream are output; c. In the purification section, sulfur compounds are removed from the preheated hydrocarbon feed, and the purified hydrocarbon feed is output. d. The purified hydrocarbon feed is heated in the pre-reformer feed preheater, and the heated purified hydrocarbon feed is output. e. In the pre-reforming section, heated and purified hydrocarbon feed from the pre-reforming unit feed preheater is pre-reformed in the presence of at least a portion of the superheated steam from the steam superheater, and a first synthesis gas stream is output. f. In the self-heating reforming section, at least a portion of the first synthesis gas stream from the pre-reforming section and the oxygen feed are reformed, and a second synthesis gas stream is output; g. In the steam generation section, at least a portion of the second synthesis gas stream is subjected to heat exchange with the water feed to generate a third synthesis gas stream and a first steam stream; h. Feed the first portion of the third synthesis gas stream and at least a portion of the fifth synthesis gas stream into the methanol synthesis section to generate a crude methanol stream, a first tail gas stream, and a second tail gas stream; i. A second portion of the third synthesis gas stream and a portion of the third superheated steam stream are fed into the high-temperature shift converter (HTS) section to generate a fourth synthesis gas stream; j. In the steam superheater, at least a portion of the first steam stream from the steam generation section is superheated by exchanging heat with at least a portion of the fourth synthesis gas stream output from the HTS section; and the first superheated steam stream and the fifth synthesis gas stream are output. The step of heating the hydrocarbon feed in the pre-reformer feed preheater is carried out by heat exchange with at least a portion of the first superheated steam stream output from the steam superheater, thereby outputting a second superheated steam stream.

[0043] Suitablely, at the inlet of the high-temperature conversion section, the ratio of a portion of the third superheated steam flow to a second portion of the third synthesis gas flow is 0.6-0.8.

[0044] In one aspect of this method, the modulus (M = (H2 - CO2) / (CO + CO2)) of the syngas leading to the methanol synthesis section (i.e., the combined third and fifth syngas streams) is adjusted to between 1.9 and 2.2, preferably 2.00-2.10, by adding hydrogen. Depending on the natural gas feed, in many cases, autothermal reforming will be substoichiometric for methanol formation, i.e., M < 2, and therefore may require the addition of hydrogen. In conventional ATR units with a combustion heater and using purge gas and tail gas as fuel after hydrogen removal, externally sourced equilibrium hydrogen is not required. In such a layout without a combustion heater, it is likely that externally sourced hydrogen (e.g., from electrolysis) will be required.

[0045] In this method, a portion of the superheated steam stream from the steam superheater appropriately has a temperature between 420-450°C at the inlet of the pre-reforming section. The third superheated steam stream can have a temperature between 270-330°C at the inlet of the HTS section.

[0046] All aspects of the methanol equipment described above are related to the method of the present invention with the necessary modifications. Detailed Implementation

[0047] The methanol synthesis gas preferably has a composition corresponding to a so-called modulus (M=(H2-CO2) / (CO+CO2)) of 1.9-2.2 or more preferably slightly higher than 2 (e.g., 2.0-2.1). Depending on the composition of the hydrocarbon feedstock, the modulus of the methanol synthesis gas from the autothermal reforming step may be lower than the preferred value. In this case, hydrogen from, for example, water electrolysis can be added to the synthesis gas to adjust the modulus to the preferred value.

[0048] Therefore, in one embodiment of the invention, the modulus (M=(H2-CO2) / (CO+CO2)) of the methanol synthesis gas from step (e) is adjusted to a value between 1.9 and 2.2 by adding hydrogen from electrolysis to the methanol synthesis gas.

[0049] Because the preheating temperature leading to the ATR is reduced by applying this invention, oxygen consumption will increase. If the compressor in the air separation unit is driven by renewable electricity, the carbon intensity will remain unchanged.

[0050] The lower preheating temperature will also require a start-up heater for the ATR to ensure ignition. It is anticipated that this start-up heater will be of the electric heater type.

[0051] Example

[0052] An embodiment of the invention is provided. Example 1 uses a combustion heater for steam superheating and feed preheating, while Example 2 applies... Figure 1 The present invention is illustrated in the table. As can be seen from the table, in this embodiment, the carbon strength of the methanol product can be reduced by 88.5%.

[0053]

[0054] The present invention has been described with reference to several aspects and accompanying drawings. However, those skilled in the art will be able to select and combine various aspects within the scope of the invention as defined by the appended claims. All documents mentioned herein are incorporated by reference.

Claims

1. A methanol processing unit (100), the unit (100) comprising: - Hydrocarbon feed (1); - Water feed (2); - Oxygen feed (3); - A feed preheater (90) is arranged to preheat the hydrocarbon feed (1) by exchanging heat with at least a portion (42'') of a second superheated steam stream and output the preheated hydrocarbon feed (1') and a third superheated steam stream (42'''); - A purification section (80) is arranged to remove sulfur compounds from the preheated hydrocarbon feed (1') and output purified hydrocarbon feed (1''); - A pre-reformer feed preheater (10) is arranged to heat the purified hydrocarbon feed (1'') and output the heated purified hydrocarbon feed (1'''); - A pre-reforming section (20) is arranged to pre-reform heated and purified hydrocarbon feed (1''') from the pre-reforming feed preheater (10) in the presence of at least a portion of the superheated steam flow (42A) from the steam superheater (70) and output a first synthesis gas stream (21). - A self-heating reforming section (30) is arranged to receive at least a portion of a first synthesis gas stream (21) from a pre-reforming section (20) and the oxygen feed (3), and to output a second synthesis gas stream (31); - A steam generation section (40) is arranged to allow at least a portion of the second synthesis gas stream (31) to exchange heat with the water feed (2) and generate a third synthesis gas stream (41) and a first steam stream (42); - A methanol synthesis section (50) is arranged to receive at least a portion (41A) of a third synthesis gas stream (41) and a portion of a fifth synthesis gas stream (61') to generate a crude methanol stream (51), a first tail gas stream (52), and a second tail gas stream (53). - High Temperature Shift (HTS) section (60), which is arranged to receive the second part (41B) of the third synthesis gas flow (41) and a part of the third superheated steam flow (42'''), and generate the fourth synthesis gas flow (61); - A steam superheater (70) is arranged to superheat at least a portion of a first steam stream (42) from a steam generation section (40) by exchanging heat with at least a portion of a fourth synthesis stream (61) from an HTS section (60); and outputs a first superheated steam stream (42', 42A) and a fifth synthesis stream (61'); - The pre-reformer feed preheater (10) is arranged to heat the hydrocarbon feed (1'') by exchanging heat with at least a portion of a first superheated steam stream (42') from the steam superheater (70) and output a second superheated steam stream (42'').

2. The methanol apparatus (100) according to claim 1, further comprising a hydrogen feed (4) arranged to feed into the methanol synthesis section (50), preferably mixed with a first portion (41A) of a third synthesis gas stream (41).

3. The methanol apparatus (100) according to any one of the preceding claims further includes an electrolysis section arranged to provide the hydrogen feed.

4. The methanol equipment (100) according to any one of the preceding claims, wherein the electrolysis section is arranged to be powered by renewable energy.

5. The methanol apparatus (100) according to any one of the preceding claims further includes an electric steam reformer (e-SMR) arranged to generate hydrogen feed in the form of hydrogen-rich syngas, preferably wherein the hydrogen-rich syngas is arranged to superheat a third superheated steam stream (42''').

6. The methanol apparatus (100) according to any one of the preceding claims, wherein at least a first portion (52A) of the first tail gas (52) stream is arranged to be recycled from the methanol synthesis section (50) to the autothermal reforming section (30).

7. The methanol plant (100) according to any one of the preceding claims further includes a tail gas recirculation compressor (13) arranged to compress at least a portion of the second tail gas (53) from the methanol synthesis section (50) and recirculate the compressed second tail gas (53) to the autothermal reforming section (30).

8. The methanol apparatus (100) according to any one of the preceding claims further includes a methanol distillation section (110) arranged to receive a crude methanol stream (51) and output a purified methanol stream (111) and a third tail gas stream (112).

9. The methanol apparatus (100) according to any of the preceding claims, wherein at least a portion (112A) of the third tail gas stream (112) is arranged to be recirculated to the autothermal reforming section (30).

10. The methanol plant (100) according to any one of the preceding claims, wherein the hydrocarbon feed (1) is a natural gas feed.

11. A method for producing methanol in a methanol apparatus according to any one of the preceding claims, the method comprising the steps of: a. To provide a methanol apparatus according to any one of the preceding claims, b. In the feed preheater (90), the hydrocarbon feed (1) is heated by heat exchange with at least a portion of the second superheated steam stream (42''), and the preheated hydrocarbon feed (1') and the third superheated steam stream (42''') are output; c. Sulfur compounds are removed from the preheated hydrocarbon feed (1') in the purification section (80), and the purified hydrocarbon feed (1'') is output. d. The purified hydrocarbon feed (1'') is heated in the pre-reformer feed preheater (10), and the heated purified hydrocarbon feed (1''') is output; e. In the pre-reforming section (20), heated and purified hydrocarbon feed (1''') from the pre-reforming unit feed preheater (10) is pre-reformed in the presence of at least a portion of the superheated steam flow (42A) from the steam superheater (70), and a first synthesis gas flow (21) is output. f. In the self-heating reforming section (30), at least a portion of the first synthesis gas stream (21) from the pre-reforming section (20) and the oxygen feed (3) are reformed, and a second synthesis gas stream (31) is output; g. In the steam generation section (40), at least a portion of the second synthesis gas stream (31) is heat-exchanged with the water feed (2) to generate a third synthesis gas stream (41) and a first steam stream (42); h. Feed the first part (41A) of the third synthesis gas stream (41) and at least a part of the fifth synthesis gas stream (61') into the methanol synthesis section (50) to generate a crude methanol stream (51), a first tail gas stream (52) and a second tail gas stream (53); i. The second part (41B) of the third synthesis gas stream (41) and a part of the third superheated steam stream (42''') are fed into the high temperature shift (HTS) section (60) to generate the fourth synthesis gas stream (61); j. In the steam superheater (70), at least a portion of the first steam stream (42) from the steam generation section (40) is superheated by exchanging heat with at least a portion of the fourth synthesis gas stream (61) output from the HTS section (60); and the first superheated steam stream (42') and the fifth synthesis gas stream (61') are output. The step of heating the hydrocarbon feed (1) in the pre-reformer feed preheater (10) is carried out by exchanging heat with at least a portion of the first superheated steam stream (42') output from the steam superheater (70), thereby outputting a second superheated steam stream (42'').

12. The method according to claim 11, wherein at the inlet of the high-temperature conversion section (60), a portion of the third superheated steam flow (42''') is in a ratio of 0.6 to 0.8 to a second portion (41B) of the third synthesis gas flow (41).

13. The method according to any one of claims 11-12, wherein, for claim 1, the modulus (M=(H2-CO2) / (CO+CO2)) of the synthesis gas leading to the methanol synthesis section (50) is adjusted to a value between 1.9 and 2.2, preferably between 2.00 and 2.10, by adding hydrogen (4).

14. The method according to any one of claims 11-13, wherein at the inlet of the pre-reforming section (20), a portion of the superheated steam flow (42A) from the steam superheater (70) has a temperature between 420-450°C.

15. The method according to any one of claims 11-14, wherein at the inlet of the HTS section, the third superheated steam stream (42''') has a temperature between 270-330°C.

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