SYNTHESIS OF METHANOL

Description

[0001] The invention relates to a method and an apparatus for the synthesis of methanol.

[0002] Methanol can be produced using a methanol plant, which features a so-called synthesis loop. This is a piping system that typically includes a raw gas source, a methanol synthesis reactor, heat exchangers, and a separator.

[0003] One of the reactants in methanol synthesis is hydrogen. For the most environmentally friendly methanol synthesis possible, it is desirable to use hydrogen from water electrolysis powered by renewable energy. However, renewable energy sources fluctuate, so the availability of hydrogen from such a source also fluctuates. Fluctuations in the feed gas flow cause pressure fluctuations in the synthesis loop during methanol synthesis. A rapid pressure drop in the synthesis loop can damage the equipment used, especially the catalyst. Therefore, it is desirable to maintain a stable pressure in the synthesis loop. Documents WO 2023 / 281238 A1 and CN 213 708 192 u disclose methods and apparatus for the synthesis of methanol using a closed-loop synthesis setup.

[0004] Conventional methanol plants are therefore generally not operated under variable load conditions. Partial load operation is typically defined as at least approximately 70% of the plant capacity. Partial load operation in a conventional methanol plant is usually only selected when gas availability is reduced, such as during winter, which lasts for extended periods of weeks or months and can be planned in advance. A transition to steady-state partial load operation thus occurs over hours or days with very slow process adjustments to protect the equipment, especially the catalyst.

[0005] Especially in small plants, for example in CO₂-based syntheses with hydrogen from electrolysis, alternating load operation in a range between 20 and 100% is desirable, for instance to account for the availability of renewable energy. With conventional methanol plants, this alternating load operation cannot be achieved, or only with disproportionately high stress on the equipment.

[0006] The object of the present invention is to create a way to produce methanol even with fluctuating feedstocks and with particularly low stress on the equipment used.

[0007] These problems are solved by the method and the apparatus according to the independent claims. Further advantageous embodiments are specified in the dependent claims. The features described in the claims and in the description can be combined with one another in any technologically meaningful way.

[0008] According to the invention, a process for the synthesis of methanol using a piping system is presented, in which a raw gas source, a methanol synthesis reactor and a separation device are integrated, wherein a feed gas stream comprising reactants for the methanol synthesis is supplied from the raw gas source to the methanol synthesis reactor at a volumetric flow rate, wherein methanol is produced in the methanol synthesis reactor with the reactants, wherein the produced methanol is separated from an outlet stream of the methanol synthesis reactor by the separation device, wherein furthermore an auxiliary volume is integrated into the piping system such that a gas-accessible volume of the piping system depends on a liquid level in the auxiliary volume, and wherein the liquid level in the auxiliary volume is increased at least in one case of a reduction in the volumetric flow rate of the feed gas stream.

[0009] The described process allows for the production of methanol using a piping system. This piping system is part of a methanol synthesis setup. The piping system includes at least a raw gas source, a methanol synthesis reactor, and a separation unit. Additional components may also be integrated into the piping system. These can be configured as in a conventional methanol synthesis setup. Unless otherwise described herein, such additional components are not essential to the specific characteristics of this process.

[0010] The design of the piping system is also irrelevant. In the simplest case, the piping system comprises a first line connecting an outlet of the raw gas source to an inlet of the methanol synthesis reactor, and a second line connecting an outlet of the methanol synthesis reactor to an inlet of the separation unit. Preferably, the piping system further comprises a third line connecting a gas outlet of the separation unit to the first line. Gas can be recycled within the piping system via the third line, i.e., fed back into the methanol synthesis reactor. If the piping system includes the third line or an equivalent recirculation capability, it can also be referred to as a loop, particularly a synthesis loop.In addition to the two or three lines described, the piping system may have various other lines, branches and cross-connections.

[0011] The raw gas source can be a single source of raw gas that already contains a mixture of all reactants for methanol synthesis. Alternatively, the raw gas source can comprise several individual sources, each supplying only one of the reactants. The corresponding individual streams can be combined to form the feed gas stream. The point of this combination is irrelevant to the described process.

[0012] In the described process, a feed gas stream containing reactants for methanol synthesis is fed from the raw gas source to the methanol synthesis reactor. This is done at a volumetric flow rate, which is discussed in more detail below. The reactants for methanol synthesis can be, in particular, hydrogen on the one hand and carbon monoxide and / or carbon dioxide on the other. The hydrogen preferably originates, at least in part, from water electrolysis powered by renewable energy.

[0013] In the methanol synthesis reactor, methanol is produced from the reactants. This can be done in a known manner, in particular using a catalyst in the methanol synthesis reactor. An outlet stream can exit the methanol synthesis reactor, containing, in addition to the methanol, other substances, in particular H₂O formed during the methanol synthesis, as well as the reactants, insofar as these have not reacted in the methanol synthesis reactor. The produced methanol is separated from the outlet stream of the methanol synthesis reactor by the separation device. This can also be done in a known manner. The separation device can be a liquid separation device. The separation device can, in particular, be configured to separate the gas and liquid phases. In this case, the methanol can be separated as a liquid.The term "raw ethanol" is also commonly used for the exhaust stream, although the exhaust stream may contain other substances besides methanol.

[0014] Unlike conventional methanol synthesis methods, the described process involves the targeted modification of the pipeline system's volume. This utilizes the general principle that, under otherwise unchanged conditions, a reduction in the available volume of a gas is accompanied by an increase in pressure, and vice versa. Therefore, by changing the pipeline system's volume, the pressure within the system can be influenced. This principle is exploited in the described process to respond to fluctuations in the raw gas flow. This is particularly advantageous when the raw gas is at least partially generated using renewable energy sources, as can be the case with hydrogen as a feedstock for methanol synthesis. If sufficient renewable energy is not available, an insufficient amount of hydrogen can be produced for full-load operation of the methanol synthesis process.The feed gas stream is supplied to the methanol synthesis reactor at a reduced volumetric flow rate. This would generally lead to a reduction in pressure in the piping system, which in turn could damage components, especially the catalyst.

[0015] The described method can reduce or even completely prevent such a pressure reduction. This is achieved, at least in one case where the feed gas flow rate decreases, by reducing the volume of the piping system accessible to gas. As a result, despite the reduction in the feed gas flow rate, the pressure in the piping system remains constant or drops only slightly.

[0016] The volume of the piping system accessible to gas is modified using an auxiliary volume. This auxiliary volume is integrated into the piping system in such a way that the volume accessible to gas depends on the liquid level within the auxiliary volume. The auxiliary volume is part of the piping system. It can be located within a pipe or in a component integrated into the piping system. The auxiliary volume is a space within the piping system that is not completely enclosed and is thus fluidically connected to the rest of the piping system. It is not necessary for the auxiliary volume to be formed by a separate component or otherwise distinguishable from the rest of the piping system. It is possible that, in a given piping system, an auxiliary volume can be identified in several different ways and / or at several different locations.It is sufficient that liquid can collect in the auxiliary volume. This auxiliary volume can, for example, be formed in a depression in a pipeline. The precise design of the auxiliary volume is not crucial for the functionality of the method. Rather, the advantages described herein are achieved by using the auxiliary volume, as described, to adjust the volume of the pipeline system accessible to gas via the liquid level within the auxiliary volume.

[0017] The volume of the piping system accessible to gas comprises, in particular, the volumes of the pipes within the system as well as the volumes of the components integrated into the system. For example, a portion of the methanol synthesis reactor accessible to gas contributes to the volume of the piping system accessible to gas. Therefore, it is irrelevant where a boundary is drawn between the methanol synthesis reactor and a pipe connected to it.

[0018] To the extent that the auxiliary volume is not filled with liquid, it also contributes to the volume of the piping system accessible to gas. The portion of the auxiliary volume that is filled with liquid is not accessible to gas due to the liquid content. The gas-accessible portion of the auxiliary volume can therefore be varied by adjusting the amount of liquid in the auxiliary volume. Thus, it is possible to influence the gas-accessible volume of the piping system by controlling the liquid level in the auxiliary volume. In the described method, the liquid level in the auxiliary volume is therefore increased, at least in one case where the feed gas flow rate decreases. By changing the liquid level in the auxiliary volume, a decrease in the feed gas flow rate can therefore be addressed.

[0019] The described method is particularly suitable for responding to rapid fluctuations in the feed gas flow. Slower fluctuations can be addressed in other ways. To gain an advantage over a conventional method, it is therefore sufficient to increase the liquid level in the auxiliary volume at least in one instance where the feed gas flow rate decreases. The behavior of the liquid level when the feed gas flow rate increases is generally irrelevant. Similarly, the liquid level in the auxiliary volume is negligible when the feed gas flow rate is constant. It is sufficient that the liquid level is briefly increased at least in one instance where the feed gas flow rate decreases, in order to compensate for the effects of this reduction in the short term.This is because the pressure in the piping system can be influenced in ways other than level control. In particular, all methods used in a conventional methanol synthesis setup are relevant here. For example, excessive pressure can be released via a pressure relief valve, which can react relatively quickly. Generally speaking, it can also be assumed that, for example, in the production of hydrogen via electrolysis, a rapid drop in production is more likely than a rapid increase. The risk of excessive pressure is therefore qualitatively different from the risk of insufficient pressure.

[0020] Nevertheless, it is preferable that the fill level be reduced at least in one case where the feed gas flow rate increases. In this case, the change in fill level helps to stabilize the pressure in the piping system. However, given the above, it is also possible for the liquid level in the auxiliary volume to initially increase when the feed gas flow rate decreases, and then be reduced again, regardless of the feed gas flow rate, for example, to a level that existed before the increase. The timing of this reduction is irrelevant.

[0021] It is also not necessary for the liquid level in the auxiliary volume to be increased every time the feed gas flow rate decreases. It suffices that the liquid level in the auxiliary volume is increased at least once during a decrease in the feed gas flow rate, i.e., at least once during the execution of the process. In particular, in the case of a slow decrease in the feed gas flow rate, it is not necessary to react by increasing the liquid level in the auxiliary volume. However, it is preferred that the liquid level in the auxiliary volume be increased every time the feed gas flow rate decreases faster than a pressure change limit and / or every time the feed gas flow rate decreases to a value below a pressure limit.

[0022] The fluid in the auxiliary volume can also be referred to as an auxiliary fluid due to its function. However, it is not necessary for the auxiliary fluid to be used exclusively for this purpose. In particular, the auxiliary fluid can also be a fluid already present in the piping system. By avoiding the term "auxiliary fluid," it is intended to clarify that the auxiliary fluid does not have to be a separate liquid. The auxiliary volume can also be referred to as a buffer volume. Accordingly, the fluid in the auxiliary volume can also be referred to as a buffer fluid.

[0023] In a preferred embodiment of the method, the liquid comprises methanol.

[0024] Using methanol as the liquid has the advantage that no foreign substances need to be introduced into the piping system. Preferably, the liquid is pure methanol. This does not preclude the possibility that the methanol contains unavoidable impurities. Alternatively, preferably, the liquid is a methanol-water mixture with small amounts of impurities, also referred to as "crude ethanol" or "stabilized methanol," as produced during methanol synthesis.

[0025] Alternatively or in addition to methanol, the liquid can also contain other substances. For the essential functioning of the described process, it is only important that the liquid displaces gas and can thus influence the volume of the piping system accessible to gas. This is generally the case with liquids.

[0026] In a further preferred embodiment of the process, the liquid comprises methanol produced in the methanol synthesis reactor. The fact that the liquid comprises methanol means that it is not necessarily pure methanol, but can also be a mixture of methanol and, for example, water, which may also contain unavoidable byproducts.

[0027] Using methanol from the methanol synthesis reactor as the liquid has the advantage that no external liquid needs to be supplied. The volume of the piping system accessible to gas can thus be controlled simply by changing the level of the methanol already present in the auxiliary volume. This can be achieved, for example, using a pump. In this case, an external storage tank for the liquid is not required.

[0028] In a further preferred embodiment of the method, the liquid level in the auxiliary volume is increased, at least in one case of a reduction in the volumetric flow rate of the feed gas stream, by introducing the liquid at least partially from an external storage into the auxiliary volume.

[0029] In contrast to the previously described embodiment, this embodiment uses an external storage device. The external storage device is preferably a tank. The liquid in the external storage device can consist of methanol and / or one or more other substances. In particular, the liquid in the external storage device can be crude methanol, stabilized methanol, off-spec methanol, or pure methanol.

[0030] The liquid in the auxiliary volume can consist of liquid from the external storage and / or other liquid, in particular methanol from the methanol synthesis reactor. A combination of embodiments is also conceivable, whereby the liquid comprises methanol produced in the methanol synthesis reactor, and the liquid level in the auxiliary volume is increased, at least in one case of a reduction in the volumetric flow rate of the feed gas stream, by partially introducing the liquid from an external storage into the auxiliary volume. In this combination, it is particularly preferred that the liquid in the external storage is methanol.

[0031] In another preferred embodiment of the process, methanol is produced using the methanol synthesis reactor at a production rate of up to 5,000 tonnes per day.

[0032] The larger the auxiliary volume is compared to the gas-accessible volume of the rest of the piping system, the more the total gas-accessible volume of the piping system can be influenced by changes in the liquid level within the auxiliary volume. The greater this possibility of influence, the more effectively the described method can respond to fluctuations in the feed gas flow, and the greater the advantages of the described method. Therefore, it is desirable for the auxiliary volume to be as large as possible compared to the gas-accessible volume of the rest of the piping system.

[0033] For practical reasons, the larger the auxiliary volume is required, the more difficult it generally becomes to implement. Therefore, the described method is particularly suitable for small to medium-sized methanol synthesis plants. In the present embodiment, this is quantified by the methanol production rate. If the methanol synthesis reactor produces methanol at a rate of, for example, 1,000 tons per day, the plant can be described as a medium-sized plant.

[0034] For very small installations with a production rate of up to 10 tons per day, the auxiliary volume can be several times the volume of gas accessible to the rest of the piping system, while requiring relatively little cost and space. Therefore, very small installations can be operated with exceptional flexibility using the described method.

[0035] For small-scale plants with a production rate between 100 and 1,000 tons per day, the auxiliary volume can, with reasonable effort, correspond to the volume of the rest of the pipeline system accessible to gas. Therefore, the described method can be used effectively in small-scale plants with the aim of achieving particularly flexible operation.

[0036] For medium-sized plants with a production rate between 1,000 and 5,000 tons per day, an auxiliary volume on the order of the volume of the rest of the pipeline system accessible to gas is possible, but already represents a significant space requirement, so the implementation of the proposed measure may involve additional challenges.

[0037] As an alternative to the described embodiment, the method can also be used in larger plants by accepting the potentially greater effort required to realize the auxiliary volume.

[0038] Another aspect of the invention is an arrangement for the synthesis of methanol.The arrangement comprises a piping system, a raw gas source, a methanol synthesis reactor, and a separation device integrated into the piping system, wherein the raw gas source, the methanol synthesis reactor, and the separation device are interconnected via the piping system, wherein the arrangement further comprises an auxiliary volume integrated into the piping system such that a gas-accessible volume of the piping system depends on the fill level of a liquid in the auxiliary volume, and wherein the arrangement further comprises a level control system configured to increase the fill level of the liquid in the auxiliary volume at least in one case of a reduction in the volumetric flow rate of a feed gas stream supplied from the raw gas source to the methanol synthesis reactor via the piping system.

[0039] The advantages and features of the method are applicable and transferable to the arrangement, and vice versa. The arrangement is preferably configured for operation according to the method. The method is preferably carried out using the arrangement.

[0040] As described in the process, a raw gas source, a methanol synthesis reactor, and a separation unit are integrated into the piping system. The raw gas source, the methanol synthesis reactor, and the separation unit are interconnected via the piping system. The fact that the arrangement is configured for methanol synthesis implies that the aforementioned elements are connected via the piping system in such a way that methanol can be produced in the methanol synthesis reactor.

[0041] The raw gas source is connected to the methanol synthesis reactor in such a way that a feed gas stream containing reactants for methanol synthesis can be supplied from the raw gas source to the methanol synthesis reactor at a specific volumetric flow rate. The methanol synthesis reactor is configured to produce methanol from the reactants. The methanol synthesis reactor is connected to the separation unit in such a way that the produced methanol can be separated from an outlet stream of the methanol synthesis reactor using the separation unit.

[0042] The level control system is designed to adjust the liquid level in the auxiliary volume as described for the process. The level control system includes all necessary components. For example, it may include a control unit that receives an input signal indicating the flow rate of the feed gas stream and uses an output signal to control a pump so that the liquid level in the auxiliary volume is adjusted as described. The input signal may originate from a flow sensor, which is also part of the level control system.Alternatively or additionally, the level control can also be connected to a subordinate control unit or integrated into a higher-level control unit, whereby the information about the volumetric flow rate of the feed gas stream is already available in the subordinate or higher-level control unit. The pump can also be part of the level control system. Alternatively, the pump can be used for other purposes. The pump preferably has an outlet pressure in the range of 50 to 150 bar, particularly in the range of 90 to 100 bar.

[0043] In a preferred embodiment of the arrangement, the auxiliary volume is formed together with the separation device in a separator.

[0044] In a conventional methanol synthesis setup, the methanol is separated from the outlet stream of the methanol synthesis reactor by a separator. This separator is integrated into the piping system as a separate component. In the present embodiment of the described process, however, the auxiliary volume is also formed within the separator. Therefore, the term "separation unit" is used here. The separation unit comprises the elements that serve to separate the methanol from the outlet stream of the methanol synthesis reactor. In a conventional methanol synthesis setup, the terms "separation unit" and "separator" can be used synonymously. In the present embodiment of the described process, however, the separator is the overarching unit that includes the separation unit and the auxiliary volume.

[0045] Even a conventionally used separator has an area on its underside where liquid can collect. The separator used in the present embodiment of the described method can therefore, in terms of its construction, even correspond to a conventional separator. However, in a conventional arrangement, the separator is not combined with the level control described herein, which is designed to influence the pressure in the piping system. In the simplest case, the described arrangement differs from a conventional arrangement only in the design of the control system. The advantages described herein can, however, be achieved to a particularly high degree if the arrangement used is modified with regard to level control. In particular, the advantages described herein can be achieved especially if the auxiliary volume is particularly large.With a conventional separator, there is no comparable reason to provide the largest possible auxiliary volume in the separator.

[0046] In a further preferred embodiment of the arrangement, the cross-sectional area of ​​the separator in the area of ​​the auxiliary volume is at least 50% larger than, preferably twice as large as, in the area of ​​the separation device.

[0047] In this embodiment, the separator is modified with regard to level control. For this purpose, the area of ​​the separator used for the auxiliary volume is particularly large. The separator can therefore be described as bulbous.

[0048] Alternatively or additionally to a particularly large cross-section in the auxiliary volume, a particularly large auxiliary volume can also be achieved by a particularly large axial dimension of the separator. However, the particularly large cross-section in the auxiliary volume has the advantage that, even with a vertical arrangement of the separator, a particularly high pumping capacity is not required to introduce the liquid into the auxiliary volume.

[0049] In another preferred embodiment of the arrangement, the auxiliary volume is arranged below the separation device.

[0050] Even in a conventional separator, a region is generally provided below the separation unit where the separated liquid methanol can collect. In this respect, the described arrangement in the present embodiment requires no major modifications. It is even conceivable to use a conventional separator unchanged. However, the insight described here is to use the lower region of the separator as the auxiliary volume and to combine it with the described level control.

[0051] The liquid can be, in particular, crude methanol produced with the methanol synthesis reactor, which was separated in an upper part of a separator by the separation device and separated into the auxiliary volume arranged below the separation device and ran or dripped downwards into the auxiliary volume.

[0052] Positioning the auxiliary volume below the separator generally has the advantage that the separator is thereby located downstream of the auxiliary volume. Even if some of the liquid from the auxiliary volume were to be carried along by a gas flow in the piping system, this portion of the liquid would be immediately separated from the gas flow by the separator. Therefore, there is no risk of droplets migrating with the gas flow. This is particularly relevant in the preferred case where the arrangement is designed to allow the outlet flow of the methanol synthesis reactor to be recirculated. In this case, the entrained droplets could enter a recycling line. The separator prevents this.

[0053] In another preferred embodiment of the arrangement, the auxiliary volume is formed in a container which is integrated into the piping system between the methanol synthesis reactor and the separation device.

[0054] As an alternative to the embodiments described above, in which the auxiliary volume is formed in the separator, in this embodiment the auxiliary volume is formed outside the separator.

[0055] In another preferred embodiment of the arrangement, the container is designed as a knock-out drum.

[0056] In this embodiment, the auxiliary volume is integrated into a first stage of separation before the actual separator.

[0057] In a further preferred embodiment of the arrangement, at least 10%, preferably at least 30% of the total volume of the piping system accessible to fluid is formed by the auxiliary volume.

[0058] The larger the auxiliary volume is compared to the volume of the rest of the piping system accessible to gas, the more the total volume of the piping system accessible to gas can be influenced by changes in the liquid level within the auxiliary volume. Therefore, it is preferred that at least 10%, and particularly at least 30%, of the total fluid-accessible volume of the piping system be comprised of the auxiliary volume. This quantitative specification, in particular, distinguishes the described arrangement from a conventional arrangement, where there is no need for such a large auxiliary volume.

[0059] A fluid can be a gas and / or a liquid. The volume of the piping system accessible to fluid is therefore composed of the volume accessible to gas and the volume occupied by liquid.

[0060] In a further preferred embodiment, the arrangement further comprises an external storage unit, at least partially filled with the liquid, which is connected to the auxiliary volume.

[0061] In the present embodiment, the liquid level in the auxiliary volume can be increased, at least in one case where the feed gas flow rate decreases, by introducing at least some of the liquid from the external storage into the auxiliary volume. The arrangement is thus designed such that liquid can be introduced from the external storage into the auxiliary volume.

[0062] The external storage is preferably connected to the auxiliary volume via a line that is different from a connecting line between the methanol synthesis reactor and the separator.

[0063] The described arrangement differs from a conventional arrangement, in which there is no need for such external storage, particularly due to the external storage.

[0064] The invention is explained in more detail below with reference to the figures. Figuren 1 and 3 The figures show a particularly preferred embodiment, to which, however, the invention is not limited. The figures and the size relationships shown therein are only schematic. They show: Fig. 1: an arrangement according to the invention for the synthesis of methanol, Fig. 2: a separator known from the prior art, and Fig. 3: the separator of the arrangement according to the invention made of Fig. 1 .

[0065] Fig. 1 Figure 1 shows an arrangement 1 for the synthesis of methanol. The arrangement 1 comprises a piping system 4, a raw gas source 7, a methanol synthesis reactor 2, and a separator 3, which are integrated into the piping system 4. The separator 3 is formed in a separator 8, which is shown in Fig. 3 The details can be seen in the diagram. The raw gas source 7 comprises an H₂ source 14 and a CO₂ source 15. The raw gas source 7, the methanol synthesis reactor 2, and the separator 3 in the separator 8 are connected to each other via the piping system 4. Furthermore, the arrangement 1 includes a water supply line 16, which is connected to a steam drum 18. Steam emanating from the steam drum 18 can be released via a steam outlet 17.

[0066] The piping system 4 also includes a first cooler 21, a second cooler 22, a heat exchanger 23, a first compressor 24, and a second compressor 25. Optionally, a vessel 9 can also be integrated into the piping system 4 between the methanol synthesis reactor 2 and the separation unit 3. This vessel is shown with a dashed line at an exemplary position. The vessel 9 can be configured as a knockout drum.

[0067] The methanol produced by the methanol synthesis reactor 2 can be separated by the separation device 3 and discharged at a methanol outlet 19. In the event of overpressure in the piping system 4, gas can be released via a pressure relief valve 20.

[0068] The methanol synthesis reactor 2 of the arrangement 1 can produce methanol at a production rate of up to 5,000 tons per day.

[0069] Fig. 2 Figure 1 shows a separator 8 known from the prior art. This comprises a separation device 3, which is formed by a main separator 26 and a pre-separator 27. A liquid chamber 28 is provided in the lower part of the separator 8.

[0070] Fig. 3 shows the separator 8 of the arrangement 1 according to the invention. Fig. 1 . This also includes a separation device 3, which is formed by a main separator 26 and a pre-separator 27.

[0071] Through separator 8 from Fig. 3 The arrangement 1 comprises an auxiliary volume 5 which is integrated into the piping system 4 in such a way that a volume of the piping system 4 accessible to gas depends on a fill level h of a liquid 6 in the auxiliary volume 5.

[0072] The arrangement 1 further comprises a level control 12, which is configured to increase the level h of the liquid 6 in the auxiliary volume 5 at least in one case of a reduction in the volumetric flow rate of a feed gas stream supplied from the raw gas source 7 via the piping system 4 to the methanol synthesis reactor 2. For the sake of clarity, the level control 12 is shown only in Fig. 3 , but not in Fig. 1 shown.

[0073] The separating device 3 and the auxiliary volume 5 are formed in a common housing 13. The auxiliary volume 5 is arranged below the separating device 3.

[0074] Unlike separator 8 made of Fig. 2 Is separator 8 out? Fig. 3 The lower section is bulbous. A cross-section of separator 8 made of Fig. 3 Therefore, the volume in the area of ​​the auxiliary volume 5 is more than twice as large as in the area of ​​the separating device 3. This makes it possible for at least 30% of the total fluid-accessible volume of the piping system 4 to be formed by the auxiliary volume 5.

[0075] Furthermore, the arrangement 1 comprises an external storage container 10, at least partially filled with the liquid 6, which is connected to the auxiliary volume 5 via a connecting line 11. This is Fig. 3 shown, in Fig. 1 However, for the sake of clarity, no. Reference symbol list

[0076] 1. Arrangement 2. Methanol synthesis reactor 3. Separation device 4. Piping system 5. Auxiliary volume 6. Liquid 7. Raw gas source 8. Separator 9. Vessel 10. External storage 11. Connecting line 12. Level control 13. Housing 14. H₂ source 15. CO₂ source 16. Water supply line 17. Steam outlet 18. Steam drum 19. Methanol outlet 20. Overpressure relief 21. First cooler 22. Second cooler 23. Heat exchanger 24. First compressor 25. Second compressor 26. Main separator 27. Pre-separator 28. Liquid area h. Level

Claims

1. A method for synthesizing methanol using a piping system (4), into which a raw gas source (7), a methanol synthesis reactor (2), and a separation device (3) are integrated, wherein a feed gas stream comprising educts for the methanol synthesis is supplied from the raw gas source (7) to the methanol synthesis reactor (2) at a volumetric flow rate, wherein methanol is produced in the methanol synthesis reactor (2) with the educts, wherein the produced methanol is separated by the separation device (3) from an outlet stream of the methanol synthesis reactor (2), wherein furthermore an auxiliary volume (5) is integrated into the piping system (4) in such a way that a gas-accessible volume of the piping system (4) depends on a fill level (h) of a liquid (6) in the auxiliary volume (5), and wherein the fill level (h) of the liquid (6) in the auxiliary volume (5) is increased in at least one case of a reduction in the volumetric flow rate of the feed gas stream.

2. The method according to claim 1, wherein the liquid (6) comprises methanol.

3. The method according to claim 2, wherein the liquid (6) comprises methanol which was produced in the methanol synthesis reactor (2).

4. The method according to any one of the preceding claims, wherein the fill level (h) of the liquid (6) in the auxiliary volume (5) is increased in at least one case of a reduction in the volumetric flow rate of the feed gas stream by at least partially introducing the liquid (6) from an external storage (10) into the auxiliary volume (5).

5. The method according to any one of the preceding claims, wherein methanol is produced with the methanol synthesis reactor (2) at a production rate of up to 5,000 tons per day.

6. An arrangement (1) for synthesizing methanol, comprising a piping system (4) as well as a raw gas source (7), a methanol synthesis reactor (2), and a separation device (3), which are integrated into the piping system (4), wherein the raw gas source (7), the methanol synthesis reactor (2), and the separation device (3) are interconnected via the piping system (4), wherein the arrangement (1) further comprises an auxiliary volume (5), which is integrated into the piping system (4) in such a way that a gas-accessible volume of the piping system (4) depends on a fill level (h) of a liquid (6) in the auxiliary volume (5), and wherein the arrangement (1) further comprises a fill level control (12), which is configured to increase the fill level (h) of the liquid (6) in the auxiliary volume (5) in at least one case of a reduction in a volumetric flow rate of a feed gas stream supplied from the raw gas source (7) via the piping system (4) to the methanol synthesis reactor (2).

7. The arrangement (1) according to claim 6, wherein the auxiliary volume (5) is formed together with the separation device (3) in a separator (8).

8. The arrangement (1) according to claim 7, wherein a cross-sectional area of the separator (8) in the region of the auxiliary volume (5) is at least 50% larger than in the region of the separation device (3).

9. The arrangement (1) according to any one of claims 6 to 8, wherein the auxiliary volume (5) is arranged below the separation device (3).

10. The arrangement (1) according to claim 6, wherein the auxiliary volume (5) is formed in a container (9) which is integrated between the methanol synthesis reactor (2) and the separation device (3) into the piping system (4).

11. The arrangement (1) according to claim 10, wherein the container (9) is configured as a knock-out drum.

12. The arrangement (1) according to any one of claims 6 to 11, wherein at least 10% of a total fluid-accessible volume of the piping system (4) is formed by the auxiliary volume (5).

13. The arrangement (1) according to any one of claims 6 to 12, further comprising an external storage (10) at least partially filled with the liquid (6), which is connected to the auxiliary volume (5).