WO2025146379A1

WO2025146379A1 - Methanol loop boiler

Info

Publication number: WO2025146379A1
Application number: PCT/EP2024/087901
Authority: WO
Inventors: Søren Grønborg ESKESEN
Original assignee: Haldor Topsoe AS
Current assignee: Topsoe AS
Priority date: 2024-01-05
Filing date: 2024-12-20
Publication date: 2025-07-10
Anticipated expiration: 2026-07-05

Abstract

A methanol loop, and a methanol plant including said methanol loop, are provided. In addition to conventional components, the methanol loop comprises one or more additional heat exchangers, arranged to make best use of the heat energy in the effluent stream from the boiling water reactor. Processes for synthesising methanol in the methanol plants of the invention are also provided.

Description

METHANOL LOOP BOILER

TECHNICAL FIELD

A methanol loop, and a methanol plant including said methanol loop, are provided. In addition to conventional components, the methanol loop comprises one or more additional heat exchangers, arranged to make best use of the heat energy in the effluent stream from the boiling water reactor in the methanol loop. Processes for synthesising methanol in the methanol plants of the invention are also provided.

BACKGROUND

The market and technology for eMethanol (i.e. methanol produced primarily from conversion of readily-available feedstocks via electrical power) is developing rapidly, and there is a goal to replace natural gas-based methanol plants.

In a traditional distillation system for purifying raw methanol into Grade AA specification, e.g. in a natural gas based methanol plant, the energy input to the distillation reboilers comes at least partly via steam of typically 170°C and 7 bar g, because this is in abundance in such plants. The steam comes from steam boilers in the reforming section and via steam generation in the methanol synthesis section, such as in a boiling water reactor.

However, in newly developed methanol plants where the combined feedstock to the methanol synthesis section essentially consists of hydrogen and carbon dioxide, low-pressure steam (and steam in general) is insufficient for the requirements of the distillation section. No reforming section producing steam exists in these plants and the only steam-producing section is the methanol synthesis section.

With only steam generated in the synthesis section there is not enough steam for the distillation reboilers. One alternative is to cover the required energy input by importing additional steam, however, this is not always possible.

Overall, it would be beneficial if heat energy produced in the methanol loop could be utilized elsewhere in the methanol plant, in particular in the distillation section. In particular, it is an object of the present invention to provide an eMethanol loop and process in which the amount of steam produced in the methanol loop covers the overall requirements of steam in the methanol plant, in particular in the distillation section. SUMMARY

It has been found by the present inventor(s) that by installing an extra heat exchanger in the methanol synthesis loop, efficient use of heat energy from the boiling water reactor can be made, and waste of heat energy from a connected air cooler or water cooler can be limited.

So, a methanol loop is provided, said methanol loop comprising : a syngas feed, syngas compressor section, boiling water reactor, first heat exchanger, second heat exchanger, optionally, a third heat exchanger, a methanol separator, a condenser, wherein : the syngas compressor section is arranged to receive said syngas feed and to output a compressed syngas stream; the boiling water reactor is arranged to receive a second heated syngas stream from the first heat exchanger and to output a first effluent stream comprising methanol; the first heat exchanger is arranged to heat exchange a combined syngas stream or a heated combined syngas stream with the first effluent stream from the boiling water reactor and to output the second heated syngas stream and a second effluent stream; the second heat exchanger is arranged to heat exchange at least a portion of the second effluent stream from the first heat exchanger with a first stream and to output a second stream and a third effluent stream; the third heat exchanger - when present - is arranged to heat exchange at least a portion of the combined stream with at least a portion of the third effluent stream from the second heat exchanger and to output a fourth effluent stream and a heated combined syngas stream; the condenser is arranged to receive at least a portion of the third effluent stream or at least a portion of the fourth effluent stream and output a condensed effluent stream comprising methanol; the methanol separator is arranged to receive at least a portion of the condensed effluent stream and to output a raw methanol stream and an off-gas stream; wherein at least a first portion of said off-gas stream is arranged to be compressed and subsequently mixed with at least a portion of the compressed syngas stream to provide said combined syngas stream.

A first methanol plant is provided, comprising the methanol loop and a distillation section, and in which the first stream is a boiler feed, and the second stream is a first steam stream. The distillation section is arranged to receive at least a portion of the raw methanol stream from the methanol loop and distil at least a portion of it, so as to output a purified methanol stream, wherein the distillation section is further arranged to receive at least a portion of the first steam stream from the second heat exchanger and/or at least a portion of the second steam stream from the steam drum, wherein said portion of the first steam stream and/or said portion of the second steam stream is/are arranged to provide heat energy for the distillation process.

A second methanol plant is provided, comprising the methanol loop and a distillation section, and in which the second heat exchanger is a reboiler, the first stream is a liquid stream comprising methanol, and the second stream is a gaseous stream comprising methanol. The distillation section is arranged to receive at least a portion of the raw methanol stream from the methanol loop and distil at least a portion of it, so as to output a purified methanol stream, wherein the distillation section is further arranged to feed least a portion of a liquid stream comprising methanol to the second heat exchanger, and to receive least a portion of said gaseous stream comprising methanol, such that said portion of the gaseous stream comprising methanol is arranged to provide heat energy for the distillation process.

Processes for synthesising methanol in the first or second methanol plant are provided, as per independent claims 7 and 9.

Further aspects of the invention are presented in the dependent claims, the figures and the description text.

LEGENDS

The technology is illustrated by means of the following schematic illustrations, in which:

Fig. 1 shows a conventional methanol loop (prior art).

Fig. 2 shows a methanol loop according to the invention. Fig. 3 shows a further methanol loop according to the invention.

Fig. 4 shows a methanol plant according to the invention.

DETAILED DISCLOSURE

Unless otherwise specified, any given percentages for gas content are % by volume. All feeds are preheated as required.

In general terms, the methanol loop comprises: a syngas feed; syngas compressor section, boiling water reactor, first heat exchanger, second heat exchanger, optionally, a third heat exchanger, a methanol separator, a condenser.

These components will be discussed further in the following.

A synthesis gas (syngas) feed refers to a feed comprising CO, CO2 and H2. It can be produced by (co-)electrolysis of H2O and CO2.

Optimally, the syngas feed to the methanol loop should only contain 2-3% CO2. High amounts of CO2 will result in an increased production of steam because of need to shift the CO2 to CO in the methanol synthesis reactor, giving an overall lower reaction rate and a higher degree of catalyst deactivation.

The syngas compressor section is arranged to receive the syngas feed and to output a compressed syngas stream. The compressor section may comprise 1 or more individual compressors. A compressed syngas stream is thus provided. This arrangement allows the compressed syngas stream to reach the required pressure upstream the boiling water reactor. The boiling water reactor, is arranged to receive a second heated syngas stream from the first heat exchanger and to output a first effluent stream comprising methanol. The boiling water reactor has to accommodate the following two reactions:

CO₂ + H₂ < = > CO + H₂O

CO + 2H₂ < = > CH₃OH

The boiling water reactor effluent stream comprises methanol, water, unreacted synthesis gas and optionally other byproducts, such as water, dimethyl ether and higher alcohols and hydrocarbons.

The methanol loop comprises first, second and optionally, third heat exchangers, arranged to make best use of the heat in the effluent from the exothermic processes in the boiling water reactor.

The first heat exchanger is arranged to heat exchange a combined syngas stream or a heated combined syngas stream with the first effluent stream from the boiling water reactor and to output a second heated syngas stream and a second effluent stream.

The second effluent stream or at least a portion of the second effluent stream from the first heat exchanger is fed to the second heat exchanger. The second heat exchanger is arranged to heat exchange at least a portion of the second effluent stream from the first heat exchanger with a first stream and to output a second stream and a third effluent stream.

The third effluent stream or at least a portion of the third effluent stream may be fed to a third heat exchanger (where present). The third heat exchanger is arranged to heat exchange at least a portion of the combined stream with at least a portion of the third effluent stream from the second heat exchanger and to output a fourth effluent stream and a heated combined syngas stream.

These cooling processes not only help to recover some of the heat energy for use elsewhere in the plant, but also begins the process of condensing the methanol out of the effluent stream.

The condenser is arranged to receive at least a portion of the third effluent stream or at least a portion of the fourth effluent stream (where present) and to output a condensed effluent stream comprising methanol. Here, further cooling causes some of the methanol and water vapor in the effluent stream to condense into a liquid phase, while the unreacted gases and inerts remain in a gas phase. The condensation temperature of the effluent stream varies depending on the methanol loop pressure, i.e., the condensation temperature of a fluid is the temperature at which a phase change occurs under a given pressure. In other words, it is the temperature at which the fluid starts to condense from a gas to a liquid or boil from a liquid to a gas.

The methanol separator is arranged to receive at least a portion of the condensed effluent stream and to output a raw methanol stream and an off-gas stream. The raw methanol stream is in the form of a liquid phase, separated from the bottom of the methanol separator. This raw methanol stream contains primarily methanol and water, and at least a portion of said raw methanol stream, preferably all, is sent to a distillation section for further purification.

The off-gas stream from the methanol separator comprises mostly unreacted syngas components. At least a portion of this off-gas stream is recycled to the boiling water reactor (hence methanol "loop"). At least a first portion of the off-gas stream is arranged to be compressed and subsequently mixed with at least a portion of the compressed syngas stream to provide the combined syngas stream. Compression compensates for the pressure drop due to friction in any equipment the gas goes through, and the pressure of the off-gas stream is increased to match the pressure of said portion of the compressed syngas stream.

In one aspect, the first stream is a boiler feed, and the second stream is a first steam stream. The first steam stream or at least a portion of the first stream may be used as a source of heat elsewhere in the methanol plant. In this way, the second heat exchanger may be a boiler.

In another aspect, the second heat exchanger is a reboiler, the first stream is a liquid stream comprising methanol, and the second stream is a gaseous stream comprising methanol. In this aspect, the reboiler is used to provide heat to a distillation column, in that a liquid stream comprising methanol is removed from the distillation column, at least a portion of it is heated in the reboiler, and at least a portion of the resulting gaseous stream comprising methanol is returned to the distillation column.

The methanol loop may further comprise a steam drum, and a water feed stream provided to said steam drum. The steam drum is arranged to receive a first water stream from the boiling water reactor, and to provide a second water stream, and to feed at least a portion of said second water stream back to the boiling water reactor. The second water stream is cooler than the first water stream, and acts to regulate the temperature of the boiling water reactor. Preferably, the first water stream is a two-phase stream comprising liquid water and steam. Preferably, the steam drum is also arranged to output a second steam stream, which can provide an additional source of steam/heat energy in the methanol plant.

Further provided is a methanol plant, comprising the methanol loop according to the first aspect, and a distillation section. The distillation section is arranged to receive at least a portion of the raw methanol stream from the methanol loop and distil at least a portion of it, so as to output a purified methanol stream. The distillation section is further arranged to receive at least a portion of the first steam stream from the second heat exchanger and/or at least a portion of the second steam stream from the steam drum. Accordingly, said portion of the first steam stream and/or said portion of the second steam stream is/are arranged to provide heat energy for the distillation process.

The distillation section is arranged to cool at least a portion of said first steam stream and/or at least a portion of the second steam stream to a cooled stream, preferably wherein at least a portion of said cooled stream is fed as at least a portion of said first stream to the second heat exchanger.

A process for synthesising methanol in this methanol plant is also provided. The process comprises the steps of: feeding the syngas feed to the syngas compressor section and outputting a compressed syngas stream; feeding at least a portion of the second heated syngas stream from the first heat exchanger to the boiling water reactor and outputting a first effluent stream comprising methanol; heat exchanging a combined syngas stream or a heated combined syngas stream with at least a portion of the first effluent stream from the boiling water reactor in the first heat exchanger and outputting the second heated syngas stream and a second effluent stream ; heat exchanging at least a portion of the second effluent stream from the first heat exchanger with a first stream in the second heat exchanger and outputting a second stream and a third effluent stream wherein the first stream is a boiler feed, and the second stream is a first steam stream; optionally heat exchanging at least a portion of the combined stream with at least a portion of the third effluent stream from the second heat exchanger in the third heat exchanger and outputting a fourth effluent stream and a heated combined syngas stream ; feeding at least a portion of the third effluent stream or at least a portion of the fourth effluent stream to the condenser and outputting a condensed effluent stream comprising methanol; feeding at least a portion of the condensed effluent stream to the methanol separator and outputting a raw methanol stream and an off-gas stream ; compressing at least a first portion of said off-gas stream and subsequently mixing with at least a portion of the compressed syngas stream to provide said combined syngas stream ; feeding at least a portion of the raw methanol stream from the methanol loop to the distillation section, and distilling at least a portion of it, so as to output a purified methanol stream; feeding at least a portion of the first steam stream from the second heat exchanger and/or at least a portion of the second steam stream from the steam drum, to the distillation section wherein said portion of the first steam stream and/or said portion of the second steam stream is/are arranged to provide heat energy for the distillation process.

Further provided is a methanol plant, comprising the methanol loop according to the second aspect, and a distillation section. The distillation section is arranged to receive at least a portion of the raw methanol stream from the methanol loop and distil at least a portion of it, so as to output a purified methanol stream. The distillation section is further arranged to feed a liquid stream comprising methanol to the second heat exchanger, and to receive at least a portion of said gaseous stream comprising methanol, such that said portion of the gaseous stream comprising methanol is arranged to provide heat energy for the distillation process.

A process for synthesising methanol in this methanol plant is also provided, said process comprising the steps of: feeding the syngas feed to the syngas compressor section and outputting a compressed syngas stream; feeding at least a portion of the second heated syngas stream from the first heat exchanger to the boiling water reactor and outputting a first effluent stream comprising methanol; heat exchanging a combined syngas stream or a heated combined syngas stream with at least a portion of the first effluent stream from the boiling water reactor in the first heat exchanger and outputting the second heated syngas stream and a second effluent stream; heat exchanging at least a portion of the second effluent stream from the first heat exchanger with a first stream in the second heat exchanger and outputting a second stream and a third effluent stream ; wherein the second heat exchanger is a reboiler, the first stream is a liquid stream comprising methanol, and the second stream is a gaseous stream comprising methanol; optionally heat exchanging at least a portion of the combined stream with at least a portion of the third effluent stream from the second heat exchanger in the third heat exchanger and outputting a fourth effluent stream and a heated combined syngas stream; feeding at least a portion of the third effluent stream or at least a portion of the fourth effluent stream to the condenser and outputting a condensed effluent stream comprising methanol; feeding at least a portion of the condensed effluent stream to the methanol separator and outputting a raw methanol stream and an off-gas stream; compressing at least a first portion of said off-gas stream and subsequently mixing with at least a portion of the compressed syngas stream to provide said combined syngas stream; feeding at least a portion of the raw methanol stream from the methanol loop to the distillation section, and distilling at least a portion of it, so as to output a purified methanol stream; feeding at least a portion of the liquid stream comprising methanol from the distillation section to the second heat exchanger and feeding at least a portion of the gaseous stream comprising methanol from the second heat exchanger to the distillation section.

The methanol plant(s) described herein may additionally comprise a feed preheater. The feed preheater is arranged to pre-heat at least a portion of the raw methanol stream using heat from third effluent stream and/or at least a portion of the fourth effluent stream, prior to said portion of the raw methanol stream being fed to the distillation section.

Additionally the distillation section may comprise a distillation heater. The distillation heater is arranged to heat one or more internal streams in said distillation section, using heat from third effluent stream and/or the fourth effluent stream.

Figure 1 shows a conventional methanol loop:

A - syngas feed

B - syngas compressor

C - feed/effluent heat exchanger D - boiling water reactor

E - steam drum

F - cooler

G - methanol separator

H - raw methanol stream

J - purge gas stream

K - recycle compressor

Figure 2 shows a methanol loop (100) according to the invention, comprising : a syngas feed (1); syngas compressor section (10), boiling water reactor (20) first heat exchanger (30) second heat exchanger (40) a methanol separator (60) a condenser (70).

The syngas compressor section (10) is arranged to receive the syngas feed (1) and to output a compressed syngas stream (11). The boiling water reactor (20) is arranged to receive a second heated syngas stream (32) from the first heat exchanger (30) and to output a first effluent stream (21) comprising methanol. The first heat exchanger (30) is arranged to heat exchange a combined syngas stream (12) with the first effluent stream (21) from the boiling water reactor (20) and to output the second heated syngas stream (32) and a second effluent stream (31). The second heat exchanger (40) is arranged to heat exchange the second effluent stream (31) from the first heat exchanger (30) with a first stream (2A, 2B) and to output a second stream (42A, 42B) and a third effluent stream (41). The condenser (70) is arranged to receive the third effluent stream (41) or the fourth effluent stream (51) and output a condensed effluent stream (71) comprising methanol. The methanol separator (60) is arranged to receive the condensed effluent stream (71) and to output a raw methanol stream (61) and an off-gas stream (62). At least a first portion (62A) of said off-gas stream (62) is arranged to be compressed and subsequently mixed with the compressed syngas stream (11) to provide said combined syngas stream (12). A second portion (62B) of the offgas stream (62) is outputted from the methanol loop (100) as a purge gas stream.

Figure 2 also illustrates a steam drum (25) having a water feed stream (19) provided to said steam drum. The steam drum is arranged to receive a first water stream (22) from the boiling water reactor (20), and to provide a second water stream (23), and to feed said second water stream (23) back to the boiling water reactor (20). The steam drum (25) as illustrated is also arranged to output a second steam stream (26).

Figure 3 shows a methanol loop (100) having the same components as Figure 2, with the same numbering. The embodiment of Figure 3 comprises a third heat exchanger (50).

The third heat exchanger (50) is arranged to heat exchange the combined stream (12) with the third effluent stream (41) from the second heat exchanger (40) and to output a fourth effluent stream (51) and a heated combined syngas stream (52). In this layout, the condenser (70) is arranged to receive the fourth effluent stream (51) and output a condensed effluent stream (71) comprising methanol. In this layout, the first heat exchanger (30) is arranged to heat exchange the heated combined syngas stream (52) with the first effluent stream (21) from the boiling water reactor (20) and to output the second heated syngas stream (32) and a second effluent stream (31).

Figure 4 shows a methanol plant according to the invention. The methanol plant comprises the methanol loop (100) as per Figure 3, and a distillation section (200). The distillation section (200) is arranged to receive the raw methanol stream (61) from the methanol loop (100) and distil it, so as to output a purified methanol stream (201). The distillation section (200) is further arranged to receive the first steam stream (42) from the second heat exchanger (40) and/or the second steam stream (26) from the steam drum (25). The first steam stream (42A) and/or the second steam stream (26) is/are arranged to provide heat energy for the distillation process.

In the layout of Figure 4, the distillation section (200) is arranged to cool the first steam stream (42A) and/or the second steam stream (26) to a cooled stream (202), and at least a portion of said cooled stream (202) is fed as at least a portion of said first stream (2A) to the second heat exchanger (40). Examples

In this example, the power generated from the methanol loop is determined for a series of different loop arrangements. The methanol plant is set to produce 167952 kg of methanol per hour (as 100% methanol). .

Example 1 : A conventional methanol loop is arranged such that steam from steam drum is arranged to provide energy (Fig. 1). In this example, 53.7 MW of energy in the form of steam is provided from steam drum E.

Example 2: The methanol loop is arranged such that that the second heat exchanger is a boiler (Fig. 3) then it can provide 21.8 MW of energy in the form of steam. Further, if a liquid feed preheater (not shown) is included together with the boiler, another 8.3 MW of energy can be provided to the distillation section. A total of 30.1 MW. In this way, the excess heat in the second effluent syngas is utilized.

Example 3: The methanol loop is arranged such that the second heat exchanger is a reboiler, wherein a distillation section is arranged to feed a liquid stream comprising methanol to the second heat exchanger, and to receive at least a portion of said gaseous stream comprising methanol, such that said portion of the gaseous stream comprising methanol is arranged to provide heat energy for the distillation process (specific embodiment of Fig. 4). In this case, the reboiler can provide 26.1 MW of energy to the distillation section. Further, if a liquid feed preheater (not shown) is included together with the reboiler, another 8.3 MW of energy can be provided to the distillation section. A total of 34.4 MW. In this way, the excess heat in the second effluent syngas is utilized.

In comparison, a distillation section receiving the above-mentioned amount of methanol can be designed to consume 117 MW of energy from steam, if the distillation is optimized.

The examples show that a methanol loop comprising a second heat exchanger (such as a boiler or reboiler) can be arranged to provide an additional contribution to the energy generated in a conventional methanol loop. In addition, the examples show that there may still be a gap to cover the required heat energy for the distillation section. The gap of required heat energy that exists after implementation of the invention could be covered by importing energy in the form of steam, utilizing heat from elsewhere in the complex, electrical reboiling, or a heat pump.

Claims

1. A methanol loop (100), said methanol loop comprising : a syngas feed (1); syngas compressor section (10), boiling water reactor (20) first heat exchanger (30) second heat exchanger (40) optionally, a third heat exchanger (50), a methanol separator (60) a condenser (70) wherein : the syngas compressor section (10) is arranged to receive said syngas feed (1) and to output a compressed syngas stream (11); the boiling water reactor (20) is arranged to receive a second heated syngas stream (32) from the first heat exchanger (30) and to output a first effluent stream (21) comprising methanol; the first heat exchanger (30) is arranged to heat exchange a combined syngas stream (12) or a heated combined syngas stream (52) with at least a portion of the first effluent stream (21) from the boiling water reactor (20) and to output the second heated syngas stream (32) and a second effluent stream (31); the second heat exchanger (40) is arranged to heat exchange at least a portion of the second effluent stream (31) from the first heat exchanger (30) with a first stream (2A, 2B) and to output a second stream (42A, 42B) and a third effluent stream (41); the third heat exchanger (50) - when present - is arranged to heat exchange at least a portion of the combined stream (12) with at least a portion of the third effluent stream (41) from the second heat exchanger (40) and to output a fourth effluent stream (51) and a heated combined syngas stream (52); the condenser (70) is arranged to receive at least a portion of the third effluent stream (41) or at least a portion of the fourth effluent stream (51) and output a condensed effluent stream (71) comprising methanol; the methanol separator (60) is arranged to receive at least a portion of the condensed effluent stream (71) and to output a raw methanol stream (61) and an off-gas stream (62), wherein at least a first portion (62A) of said off-gas stream (62) is arranged to be compressed and subsequently mixed with at least a portion of the compressed syngas stream (11) to provide said combined syngas stream (12).

2. The methanol loop (100) according to claim 1, wherein the first stream is a boiler feed (2A), and the second stream is a first steam stream (42A).

3. The methanol loop (100) according to claim 1, wherein the second heat exchanger (40) is a reboiler, the first stream is a liquid stream comprising methanol (2B), and the second stream is a gaseous stream comprising methanol (42B).

4. The methanol loop (100) according to any one of the preceding claims, further comprising a steam drum (25), and a water feed stream (19) provided to said steam drum, said steam drum being arranged to receive a first water stream (22) from the boiling water reactor (20), and to provide a second water stream (23), and to feed at least a portion of said second water stream (23) back to the boiling water reactor (20), preferably wherein the steam drum (25) is also arranged to output a second steam stream (26).

5. A methanol plant, said methanol plant comprising the methanol loop (100) according to claim 2 or claim 4, and a distillation section (200), wherein the distillation section (200) is arranged to receive at least a portion of the raw methanol stream (61) from the methanol loop (100) and distil at least a portion of it, so as to output a purified methanol stream (201), wherein the distillation section (200) is further arranged to receive at least a portion of the first steam stream (42) from the second heat exchanger (40) and/or at least a portion of the second steam stream (26) from the steam drum (25), wherein said portion of the first steam stream (42A) and/or said portion of the second steam stream (26) is/are arranged to provide heat energy for the distillation process.

6. The methanol plant according to claim 5, wherein the distillation section (200) is arranged to cool at least a portion of the first steam stream (42A) and/or at least a portion of the second steam stream (26) to a cooled stream (202), preferably wherein at least a portion of said cooled stream (202) is fed as at least a portion of said first stream (2A) to the second heat exchanger (40).

7. A process for synthesising methanol in a methanol plant according to any one of claims 5-6, said process comprising the steps of: feeding the syngas feed (1) to the syngas compressor section (10) and outputting a compressed syngas stream (11); feeding at least a portion of the second heated syngas stream (32) from the first heat exchanger (30) to the boiling water reactor (20) and outputting a first effluent stream (21) comprising methanol; heat exchanging a combined syngas stream (12) or a heated combined syngas stream (52) with at least a portion of the first effluent stream (21) from the boiling water reactor (20) in the first heat exchanger (30) and outputting the second heated syngas stream (32) and a second effluent stream (31); heat exchanging at least a portion of the second effluent stream (31) from the first heat exchanger (30) with a first stream in the second heat exchanger (40) and outputting a second stream (42) and a third effluent stream (41) wherein the first stream is a boiler feed (2A), and the second stream is a first steam stream (42A); optionally heat exchanging at least a portion of the combined stream (12) with at least a portion of the third effluent stream (41) from the second heat exchanger (40) in the third heat exchanger (50) and outputting a fourth effluent stream (51) and a heated combined syngas stream (52); feeding at least a portion of the third effluent stream (41) or at least a portion of the fourth effluent stream (51) to the condenser (70) and outputting a condensed effluent stream (71) comprising methanol; feeding at least a portion of the condensed effluent stream (71) to the methanol separator (60) and outputting a raw methanol stream (61) and an off-gas stream (62); compressing at least a first portion (62A) of said off-gas stream (62) and subsequently mixing with at least a portion of the compressed syngas stream (11) to provide said combined syngas stream (12); feeding at least a portion of the raw methanol stream (61) from the methanol loop (100) to the distillation section (200), and distilling at least a portion of it, so as to output a purified methanol stream (201); feeding at least a portion of the first steam stream (42A) from the second heat exchanger (40) and/or at least a portion of the second steam stream (26) from the steam drum (25), to the distillation section (200) wherein said portion of the first steam stream (42A) and/or said portion of the second steam stream (26) is/are arranged to provide heat energy for the distillation process.

8. A methanol plant, said methanol plant comprising the methanol loop (100) according to claim 3 or claim 4, and a distillation section (200), wherein the distillation section (200) is arranged to receive at least a portion of the raw methanol stream (61) from the methanol loop (100) and distil at least a portion of it, so as to output a purified methanol stream (201), wherein the distillation section (200) is further arranged to feed a liquid stream comprising methanol to the second heat exchanger (40), and to receive at least a portion of said gaseous stream comprising methanol, such that said portion of the gaseous stream comprising methanol is arranged to provide heat energy for the distillation process.

9. A process for synthesising methanol in a methanol plant according to claim 8, said process comprising the steps of: feeding the syngas feed (1) to the syngas compressor section (10) and outputting a compressed syngas stream (11); feeding at least a portion of the second heated syngas stream (32) from the first heat exchanger (30) to the boiling water reactor (20) and outputting a first effluent stream (21) comprising methanol; heat exchanging at least a portion of the combined syngas stream (12) or a heated combined syngas stream (52) with at least a portion of the first effluent stream (21) from the boiling water reactor (20) in the first heat exchanger (30) and outputting the second heated syngas stream (32) and a second effluent stream (31); heat exchanging at least a portion of the second effluent stream (31) from the first heat exchanger (30) with a first stream in the second heat exchanger (40) and outputting a second stream and a third effluent stream (41); wherein the second heat exchanger (40) is a reboiler, the first stream is a liquid stream comprising methanol (2B), and the second stream is a gaseous stream comprising methanol (42B); optionally heat exchanging at least a portion of the combined stream (12) with at least a portion of the third effluent stream (41) from the second heat exchanger (40) in the third heat exchanger (50) and outputting a fourth effluent stream (51) and a heated combined syngas stream (52); feeding at least a portion of the third effluent stream (41) or at least a portion of the fourth effluent stream (51) to the condenser (70) and outputting a condensed effluent stream (71) comprising methanol; feeding at least a portion of the condensed effluent stream (71) to the methanol separator (60) and outputting a raw methanol stream (61) and an off-gas stream (62); compressing at least a first portion (62A) of said off-gas stream (62) and subsequently mixing with at least a portion of the compressed syngas stream (11) to provide said combined syngas stream (12); feeding at least a portion of the raw methanol stream (61) from the methanol loop (100) to the distillation section (200), and distilling at least a portion of it, so as to output a purified methanol stream (201); feeding at least a portion of the liquid stream comprising methanol from the distillation section (200) to the second heat exchanger (40) and feeding at least a portion of the gaseous stream comprising methanol from the second heat exchanger (40) to the distillation section (200).

10. The methanol plant according to any one of claims 5, 6 or 8, said methanol plant additionally comprising a feed preheater, said feed preheater being arranged to pre-heat at least a portion of the raw methanol stream (61) using heat from third effluent stream (41) and/or at least a portion of the fourth effluent stream (51), prior to said portion of the raw methanol stream (61) being fed to the distillation section (200).

11. The methanol plant according to any one of claims 5, 6, 8 or 10, wherein said distillation section additionally comprises a distillation heater, said distillation heater being arranged to heat one or more internal streams in said distillation section, using heat from third effluent stream (41) and/or the fourth effluent stream (51).