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EP-4735410-A1 - SYSTEM AND METHOD FOR THE PREPARATION OF BLUE METHANOL

EP4735410A1EP 4735410 A1EP4735410 A1EP 4735410A1EP-4735410-A1

Abstract

A system and a process for producing blue methanol are provided, where blue methanol is understood as methanol produced under conditions limiting the emission of CO 2 . The system comprises a shift section, a CO 2 removal section and in a preferred embodiment also a hydrogen recovery section, arranged downstream a methanol synthesis section.

Inventors

  • ESKESEN, Søren, Grønborg
  • DAHL, Per, Juul
  • SHIM, TINE

Assignees

  • Topsoe A/S

Dates

Publication Date
20260506
Application Date
20240801

Claims (20)

  1. 1. A system (100) for producing methanol, said system (100) comprising : a hydrocarbon feed (1); a steam feed (2); optionally, an oxygen feed (3); a reformer section (A) arranged to receive said hydrocarbon feed (1), said steam feed (2) and, where present, said oxygen feed (3), and to provide a first synthesis gas stream (4); a cooling train (B), arranged to receive at least a portion of the first synthesis gas stream (4), and provide a second synthesis gas stream (5) and a third synthesis gas stream (10); a methanol synthesis section (C) arranged to receive at least a portion of the second synthesis gas stream (5), optionally in admixture (6) with a hydrogen-rich stream (14), and to provide a raw methanol stream (7), a first flash gas stream (20) and a purge gas stream (9); a distillation section (D) arranged to receive at least a portion of the raw methanol stream (7) and to provide a product methanol stream (8) and an off-gas stream (21); a shift section (E) arranged to receive at least a portion of said purge gas stream (9), at least a portion of said third synthesis gas stream (10), optionally a steam feed (2b), and provide a shifted gas stream (11); a CO2 removal section (F) arranged to receive at least a portion of the shifted gas stream (11) and provide a CCh-rich gas stream (12) and a first CCh-depleted gas stream (13), optionally a second flash gas stream (12b); wherein at least one of i) at least a portion of the first flash gas stream (20, 20b) from the methanol synthesis section (C), ii) at least a portion of the off-gas stream (21, 21b) from the distillation section (D), is/are arranged to be fed as additional carbon comprising feed(s) to the reformer section (A), and/or to the shift section (E).
  2. 2. The system according to claim 1, wherein at least a portion of the second flash gas stream (12b) from the CO2 removal section (F), is arranged to be fed to the reformer section (A) as an additional carbon comprising feed.
  3. 3. The system according to any one of the preceding claims, wherein the shift section (E) comprises one or more shift reactors.
  4. 4. The system according to any one of the preceding claims, further comprising a hydrogen recovery section (G), said hydrogen recovery section (G) being arranged to receive at least a portion of the first CCh-depleted gas stream (13), and to provide at least a first hydrogen-rich stream (14), and at least a first off-gas stream (15).
  5. 5. The system according to claim 4, wherein said system is arranged to provide at least a first portion (15a) of the first off-gas stream (15) to the reformer section (A) as an additional carbon comprising feed.
  6. 6. The system according to any one of claims 4 or 5, wherein the system is arranged to provide at least a first portion (14b) of the hydrogen-rich stream (14) to the methanol synthesis section (C), preferably in admixture (6) with the second synthesis gas stream (5).
  7. 7. The system according to any one of claims 4 to 6, wherein the system further comprises a fuel system (H) and wherein said hydrogen recovery section (G) is arranged to provide a second portion (15b) of the first off-gas stream (15) and/or a second portion (14c) of the hydrogen-rich stream (14), wherein at least a portion of said second portion (15b) of the first off-gas stream (15) and/or at least a portion of said second portion (14c) of the hydrogen-rich stream (14) is arranged to be fed as a fuel feed to said fuel system (H) and/or an auxiliary steam boiler and/or a gas turbine.
  8. 8. The system according to any one of the preceding claims, wherein the system further comprises a fuel system (H) and wherein at least a portion of the first CCh-depleted gas stream (13) is arranged to be split into at least a second CCh-depleted gas stream (22) and at least a third CC -depleted gas stream (23), wherein at least a portion of said second CO2- depleted gas stream (22) is arranged to be fed as a fuel feed to said fuel system (H).
  9. 9. The system according to any one of claims 1 to 3, wherein at least a portion of the first CCh-depleted gas stream (13) is arranged to be split into at least a second CCh-depleted gas stream (28) and at least a third CC -depleted gas stream (29) wherein at least a portion of said second CCh-depleted gas stream (28) is arranged to be provided to the methanol synthesis section (C), preferably in admixture (6) with the second synthesis gas stream (5).
  10. 10. The system according to any one of the preceding claims, wherein the cooling train (B) is arranged to provide sensible heat to produce steam, superheat steam, re-boiling duty for distillation and water preheat and/or allow for separation of condensed H2O.
  11. 11. The system according to any one of the preceding claims, wherein cooling train (B) is arranged to provide the third synthesis gas stream (10) at a higher temperature than the second synthesis gas stream (5, 6), preferably wherein the temperature of the third synthesis gas stream (10) is between 10°C greater than the dew point of the third synthesis gas stream (10), and 360°C.
  12. 12. The system according to any one of the preceding claims, wherein the second synthesis gas stream (5, 6) has a module between 1.8 and 2.2, preferably between 1.9 and 2.1.
  13. 13. The system according to any one of the preceding claims, wherein said steam feed (2b) is arranged to be mixed with the purge gas stream (9) and/or the third synthesis gas stream (10) and/or the first flash gas stream (20) and/or the off-gas stream (21) from said distillation section (D) prior to being inlet to the shift section (E).
  14. 14. A process for producing methanol in a system (100) according to any one of the preceding claims, said process comprising the steps of: feeding the hydrocarbon feed (1), the steam feed (2) and, where present, the oxygen feed (3) to the reformer section (A) to provide a first synthesis gas stream (4); feeding at least a portion of the first synthesis gas stream (4) to the cooling train (B) to provide a second synthesis gas (5) and a third synthesis gas (10); feeding at least a portion of the second synthesis gas stream (5), optionally in admixture (6) with a hydrogen-rich stream (14), to a methanol synthesis section (C) and converting at least a portion of the second synthesis gas stream (5, 6) to a raw methanol stream (7), a first flash gas stream (20) and a purge gas stream (9); feeding at least a portion of the raw methanol stream (7) to a distillation section (D) to provide a product methanol stream (8) and an off-gas stream (21); feeding at least a portion of the purge gas stream (9), at least a portion of the third synthesis gas stream (10), optionally a steam feed (2b), to the shift section (E), to provide a shifted gas stream (11); feeding at least a portion of the shifted gas stream (11) to a CO2 removal section (F) to provide a CC -rich gas stream (12) and a first CC -depleted gas stream (13), optionally a second flash gas stream (12b); and further feeding at least one of i) at least a portion of the first flash gas stream (20, 20b) from the methanol synthesis section (C), ii) at least a portion of the off-gas stream (21, 21b) from the distillation section (D), to the reformer section (A), and/or to the shift section (E) as additional carbon comprising feed(s).
  15. 15. The process according to claim 14, wherein said process further comprises feeding at least a portion of the second flash gas stream (12b) from the CO2 removal section (F), to the reformer section (A) as an additional carbon comprising feed.
  16. 16. The process according to any one of claims 14 or 15, wherein the system further comprises a hydrogen recovery section (G), said process further comprising : feeding the first CC -depleted gas stream (13) to the hydrogen recovery section (G) and separating the first CC -depleted gas stream (13) into at least a first hydrogen-rich stream (14), and at least a first off-gas stream (15).
  17. 17. The process according to any one of claim 16, wherein said process further comprising : feeding at least a first portion (15a) of the first off-gas stream (15) to the reformer section (A) as an additional carbon comprising feed.
  18. 18. The process according to any one of claim 16 or 17, wherein said process comprises providing at least a first portion (14b) of the hydrogen-rich stream (14) to the methanol synthesis section (C), preferably in admixture (6) with the second synthesis gas stream (5).
  19. 19. The process according to any one of claims 16 to 18, wherein the system further comprises a fuel system (H) and wherein a second portion (15b) of the first off-gas stream (15) and/or a second portion (14c) of the hydrogen-rich stream (14), are provided as fuel to the fuel system (H) and/or an auxiliary steam boiler and/or a gas turbine.
  20. 20. The process according to any one of claims 14-20, wherein the system further comprises a fuel system (H), and wherein at least a portion of the first CC -depleted gas stream (13) is split into at least a second CC -depleted gas stream (22) and at least a third CCh-depleted gas stream (23) and wherein at least a portion of said second CCh-depleted gas stream (22) is provided as a fuel feed to said fuel system (H).

Description

BLUE METHANOL TECHNICAL FIELD The present invention relates to a system and a process for producing blue methanol, where blue methanol is understood as methanol produced under conditions limiting the emission of CO2. The system comprises a shift section, a CO2 removal section and in a preferred embodiment also a hydrogen recovery section, arranged downstream a methanol synthesis section. BACKGROUND Current methanol production system layouts and processes often involve a limited exploitation of by-products in the purge gas stream and/or flash gas stream issued as waste from the methanol synthesis production. In some instances, the purge gas is separated into a hydrogen-rich gas stream and an off-gas stream where the hydrogen-rich gas stream is reintroduced to the methanol synthesis production line and where the off-gas stream is fed to a fuel system as energy source, where the fuel system provides energy or heat elsewhere in the production. However, current methanol production system layouts and processes result in the emission of flue gas to the atmosphere, which is associated with high CO2 emission. In addition, current system layouts and processes result in an inefficient use of off-gas, which may still have a significant CH4, CO, CO2 and H2 content. The high CO2 emission and inefficient use of off-gas both goes against the current interests of the chemical industry where - in recent years - focus has been on reducing greenhouse gas emissions and increasing energy efficiency. It is an object of embodiments of the invention to provide an effective system and process for methanol production in which at least a portion of the produced CO2 can be captured, stored and/or used elsewhere. More specifically, the present technology provides a system and process where at least a portion of a flash gas stream and/or at least a portion of an off-gas stream is reintroduced to the methanol synthesis production line and used as an alternative or additional carbon comprising feed. SUMMARY It has been found by the present inventors that the CO2 emission from the methanol production processes can be significantly reduced if a shift section and a CO2 removal section are introduced into the methanol production system layout and if at least a portion of gases isolated from the methanol production processes is reintroduced into the methanol synthesis production line. The provided system and process for producing methanol thereby increase the energy efficiency of the methanol production plant. In a first aspect, therefore, a system is provided for producing methanol, said system comprising : a hydrocarbon feed; a steam feed; optionally, an oxygen feed; a reformer section (A) arranged to receive said hydrocarbon feed, said steam feed and, where present, said oxygen feed, and to provide a first synthesis gas stream; a cooling train (B), arranged to receive at least a portion of the first synthesis gas stream, and provide a second synthesis gas stream and a third synthesis gas stream; a methanol synthesis section (C) arranged to receive at least a portion of the second synthesis gas stream, optionally in admixture with a hydrogen-rich stream, and to provide a raw methanol stream, a first flash gas stream and a purge gas stream; a distillation section (D) arranged to receive at least a portion of the raw methanol stream and to provide a product methanol stream and an off-gas stream, a shift section (E) arranged to receive at least a portion of said purge gas stream, at least a portion of said third synthesis gas stream, optionally a steam feed, and provide a shifted gas stream; a CO2 removal section (F) arranged to receive at least a portion of the shifted gas stream and provide a CC -rich gas stream and a first CCh-depleted gas stream, and optionally a second flash gas stream; wherein at least one of i) at least a portion of the first flash gas stream from the methanol synthesis section (C), ii) at least a portion of the off-gas stream from the distillation section (D), is/are arranged to be fed as additional carbon comprising feed(s) to the reformer section (A), and/or to the shift section (E). In a second aspect, a process for producing methanol in a system as described herein is also provided. The process comprises the steps of: feeding the hydrocarbon feed, the steam feed and, where present, the oxygen feed to the reformer section (A) to provide a first synthesis gas stream; feeding at least a portion of the first synthesis gas stream to the cooling train (B) to provide a second synthesis gas and a third synthesis gas; feeding at least a portion of the second synthesis gas stream, optionally in admixture with a hydrogen-rich stream, to a methanol synthesis section (C) and converting at least a portion of the second synthesis gas stream to a raw methanol stream, a first flash gas stream and a purge gas stream; feeding at least a portion of the raw methanol stream to a distillation section (D) to provide a product methanol