WO2024227519A1 - Process and plant for producing a reaction product - Google Patents

Abstract

What is proposed is a process (100, 200) for producing a process product, wherein hydrogen is provided using a water electrolysis (104, 150), wherein the hydrogen or a portion thereof is subjected to an exothermic reaction with carbon dioxide to liberate heat and obtain a product mixture containing the process product, wherein the product mixture or a portion thereof is subjected to a distillation using one or more distillation columns (122) and wherein the one or at least one of the two or more distillation columns (122) is heated using heat. It is envisaged here that at least a portion of the heat is provided using a heating system (210) comprising one or more heat pumps (201) and one or more heat storage units (202), which is supplied with the heat generated in the process. The present invention also provides a corresponding plant.

Description

Description

Process and plant for producing a reaction product

The present invention relates to a process and a plant for producing a reaction product, in particular methanol.

background

Currently, the production of methanol and its derivatives (e.g. dimethyl ether, DME) is mostly based on the reaction of synthesis gas, which contains carbon monoxide and hydrogen, in a so-called methanol synthesis cycle. In conventional processes, the reactants mentioned typically come from steam reforming or partial oxidation of carbon-containing (fossil) raw materials such as natural gas, liquid hydrocarbons or coal.

In order to limit the extent of global climate change caused by carbon dioxide emissions, the use of carbon dioxide as a carbon source for methanol production has been proposed. There are essentially two main routes for methanol production from carbon dioxide:

The first route can be described as the direct hydrogenation of carbon dioxide, where carbon dioxide is fed into the methanol synthesis cycle together with a hydrogen-containing co-feed. The gross reaction that takes place in such a cycle can be described by the reaction equation (1) given below.

CO ₂ + 3 H ₂ CH ₃ OH + H ₂ O (1 )

The second route involves carbon dioxide electrolysis or co-electrolysis, by means of which at least part of the carbon dioxide input is converted to carbon monoxide, which in turn is fed into a cycle similar to the conventional methanol synthesis cycle. The overall reaction during the electrochemical conversion of carbon dioxide into carbon monoxide can be described by the reaction equation (2) given below.

CO + 2 H ₂ — > CH ₃ OH (2)

Regardless of whether the direct hydrogenation of carbon dioxide according to reaction equation (1) or a carbon monoxide-based process according to reaction equation (2) is used, the general design of a corresponding cycle can be described as follows:

The respective feed streams are combined and compressed to a pressure of typically 50-100 bar. Depending on the origin of the feed materials, the various feed streams can be compressed separately or after they have been combined. A correspondingly formed total feed stream is combined with a recyclate stream, preheated and reacted in one or more catalyst beds. The product stream formed is cooled, the liquid reaction products are at least partially condensed and removed from the circuit, and the gaseous reactants are at least partially transferred to the aforementioned recyclate stream. The liquid reaction products are purified, typically in one or two distillation columns.

Although the present invention is described below predominantly with reference to methanol synthesis and this can represent a particularly advantageous field of application of the invention and its embodiments, the present invention and its embodiments are not only suitable for this, but in principle also for other processes in which the advantages of the invention and its embodiments explained below can unfold. Examples of corresponding processes are mentioned below and basically include all processes in which a distillation of liquid reaction products is carried out at a temperature above the ambient temperature.

The present invention now has the object of improving corresponding processes, in particular for the production of methanol, and in particular of making them more flexible and/or more energy-efficient. disclosure of the invention

Against this background, a method and a system for producing a process product with the respective features of the independent patent claims are proposed. Embodiments are the subject of the dependent patent claims and the following description.

Within the scope of the present invention, it is proposed to use one or more heat pumps in combination with thermal energy storage to provide at least part of the heat required for the purification of methanol produced from carbon dioxide or other process products. The heat pump(s) is/are used to increase the temperature level of the heat so that it corresponds to the temperature level required by a purification plant used. The storage of thermal energy makes it possible to increase the operational flexibility of the plant despite a high degree of heat integration.

As mentioned, the present invention and its embodiments are described using the example of methanol synthesis. However, the invention and its embodiments are equally suitable for use in connection with other processes, in particular in the form of so-called "power-to-liquids" processes, which require corresponding product preparation at temperatures above ambient temperature, for example the production of dimethyl ether and Fischer-Tropsch syntheses with on-site processing (distillation) of the correspondingly obtained crude products.

In corresponding processes, process reactants, in particular hydrogen, are advantageously provided by means of electrical energy, i.e. in particular by means of electrolysis, so that the basics of corresponding electrolysis processes will be briefly discussed below.

In classical water electrolysis, an aqueous alkaline solution, typically potassium hydroxide, is used as the electrolyte (AEL, alkaline electrolysis). The electrolysis with a uni- or bipolar electrode arrangement takes place at atmospheric pressure or on an industrial scale, even significantly higher. Newer developments in water electrolysis include the use of proton-conducting ion exchange membranes (SPE, Solid Polymer Electrolysis; PEM, Proton Exchange Membranes), in which the water to be electrolyzed is provided on the anode side. Electrolysis technologies using an anion exchange membrane (AEM, Anion Exchange Membrane) are also used.

The water electrolysis processes mentioned so far are low-temperature processes in which the water to be electrolyzed is in the liquid phase. In addition, so-called steam electrolysis is also used, which can also be carried out with alkaline electrolytes (i.e. as AEL) with adapted membranes, for example polysulfone membranes, and using solid oxide electrolysis cells (SOEC). The latter include in particular doped zirconium dioxide or oxides of other rare earths, which become conductive at higher temperatures. Corresponding processes are also referred to below as high-temperature electrolysis.

The term electrolysis is intended to encompass all of these processes. Low-temperature electrolysis (PEM, AEL, AEM) in particular is suitable for flexible operation that supports the energy transition to renewable energies. All processes can be used within the scope of the present invention and corresponding embodiments, also in combination.

Industrial heat pumps make it possible to increase the temperature level of a heat flow. Their operating principle is to transfer heat from a heat source to a working medium at a low temperature level, increase the pressure of the working medium, and then release the heat to a heat sink at a higher temperature level. The pressure increase can be achieved, for example, by an electrically driven compressor. The working fluid is often evaporated at the low temperature level and condensed at the high temperature level, but this is not absolutely necessary according to the general operating principle. Heat pumps are currently most commonly used for hot water preparation, e.g. in the field of building heating. Given the acute need to decarbonize the process industry, heat pumps are also increasingly being considered for use in the chemical industry. Since steam is the most common heating medium in the chemical industry, heat pumps have been developed that generate steam. The steam generated by indirect heat transfer with the heat pump's working medium can be used directly or further processed, e.g. by steam compression.

Especially in distillation columns, a methanol-rich gaseous overhead product can be compressed and condensed against the evaporator of the same column. Although this is not a closed heat pump cycle as previously described, the procedure follows the same general principle.

Renewable energy sources such as wind and sun cannot be planned or are difficult to plan in terms of their availability, i.e. their availability fluctuates over time. To ensure that the energy is available when needed, it can be stored, e.g. in the form of electrochemical, chemical or thermal energy. Storing electrochemical energy, e.g. in batteries, is efficient but costly. Storing chemical energy requires carrying out a chemical reaction and is often lossy and slow to provide.

Storing thermal energy, on the other hand, is comparatively cheap and flexible. Its disadvantage is that thermal energy cannot be easily converted into other forms of energy, such as electrical energy, with high efficiency. A simple and inexpensive way of storing thermal energy is to store sensible heat or thermal energy in cement. The storage is charged by heating cement with steam and discharged by using the heat stored in the cement to boil water and generate steam. Storing latent heat or thermal energy, on the other hand, is more expensive, but has the advantage of maintaining a constant temperature level.

Embodiments of the present invention enable a particularly advantageous storage of thermal energy.

The upgrading of methanol from a methanol synthesis can have a significant

The direct hydrogenation of carbon dioxide is not possible due to the The lower formation of by-products and the higher level of sophistication of water electrolysis compared to carbon dioxide electrolysis make this method particularly attractive. However, this method results in a less exothermic reaction than the conventional method and in a higher proportion of water in the liquid that is discharged from the synthesis circuit. The cleaning unit therefore requires more heat to operate, but has less heat available from the reaction. If high-temperature electrolysis is used in this context to provide the hydrogen reactant, the heat requirement increases further. Embodiments of the present invention solve this problem by using heat pumps.

The use of heat pumps to increase the temperature level of heat available from parts of the process is more efficient than purely electrically generating heat. However, this directly couples parts of the plant that could otherwise operate relatively independently. In the case of vapor compression as mentioned above, increasing the evaporator load requires more heat, which cannot be readily provided by a vapor condenser unless the evaporator load is first increased. In other words, such a design traditionally suffers from poor dynamics unless it is coupled with additional devices that are only used for load changes, such as start-up heaters. Embodiments of the invention also solve this problem by combining the respective proposed approaches.

The primary energy source for methanol production using electrochemically generated hydrogen and/or carbon monoxide is electricity, the availability of which can fluctuate over time, especially when using renewable energy sources such as wind and solar. Electrochemical processes such as electrolysis using proton exchange membranes (PEM) allow for extremely flexible operation. However, large-scale chemical processes such as methanol synthesis have much slower dynamics. A high degree of heat integration usually exacerbates this problem. For example, it makes commissioning a corresponding plant much more difficult. This problem is also solved by using the present invention. In the proposed process for producing a process product, which can in particular be methanol, hydrogen is provided using water electrolysis, the hydrogen or a portion thereof being subjected to an exothermic reaction with carbon dioxide to release heat and obtain a product mixture containing the process product, the product mixture or a portion thereof being subjected to distillation using one or more distillation columns, and the one or at least one of the several distillation columns being heated using heat. At least a portion of the heat is provided using a heating system which comprises one or more heat pumps and one or more heat storage units, and to which heat generated in the process is supplied. With regard to the advantages that can be achieved here, express reference is made to the above explanations.

The heat released in the exothermic reaction can be used in a first part to generate steam in a steam system and a second part can be dissipated downstream in one or more process gas heat exchangers. The heat components are generated at different temperature levels and can be used in a targeted manner.

The heat generated in the process that is supplied to the heating system can in particular comprise at least a portion of the heat that is dissipated in the one or more process gas heat exchangers. Corresponding heat generated at a lower temperature level can advantageously be raised to a higher temperature level, in particular by means of the heat pump(s), in order to be able to use and/or store it.

In embodiments of the present invention, the water electrolysis can be carried out as low-temperature electrolysis or can comprise low-temperature electrolysis. As explained above, this enables particularly flexible operation and has no additional heat requirements.

In embodiments of the invention, low-temperature electrolysis can

proton exchange membrane electrolysis, anion exchange membrane electrolysis and/or alkaline electrolysis. The present invention and its design can therefore be implemented with a wide range of electrolysis options.

In embodiments of the invention, electrolysis water can be supplied to the low-temperature electrolysis, from which heat is extracted in an electrolysis water heat exchanger, wherein the heat generated in the process, which is supplied to the heating system, comprises at least a portion of the heat extracted from the electrolysis water in the electrolysis water heat exchanger. This enables advantageous use of corresponding heat, which can be raised to a suitable temperature level in particular by means of the heat pump(s).

The heat generated in the process, which is fed to the heating system, can in particular comprise heat from the steam generated in the steam system in the case of low-temperature electrolysis. This heat can in particular be generated without raising the temperature level by means of the heat pump(s) and can be fed directly into the heat storage unit or used appropriately.

Additionally or alternatively, the water electrolysis can be carried out as high-temperature electrolysis or can include high-temperature electrolysis. As mentioned, this requires additional heat in particular. The high-temperature electrolysis can be carried out in particular as solid oxide electrolysis.

In embodiments of the invention, a hydrogen-rich stream can be taken from the high-temperature electrolysis and subjected to compression with the release of compression heat, whereby the heat generated in the process, which is fed to the heating system, can comprise at least part of the compression heat. This heat can also be brought to a suitable temperature level by means of the heat pump(s).

In the process, the high-temperature electrolysis can be carried out in particular using heat which comprises heat of the steam generated in the steam system or a part thereof, wherein the heat generated in the process which is supplied to the heating system comprises only a part or none of the Heat of the steam generated in the steam system. In this way, this heat can be used in a particularly targeted manner.

In embodiments of the invention, the heating system can be operated using steam compression and/or electric heating, with reference to the explanations below for further details.

As mentioned, methanol in particular can be produced as the process product in the process. Other processes and the process products produced thereby are explained above.

The proposed plant for producing a process product is designed to provide hydrogen using water electrolysis, to subject the hydrogen or a portion thereof to an exothermic reaction with carbon dioxide to release heat and obtain a product mixture containing the process product, to subject the product mixture or a portion thereof to distillation using one or more distillation columns, and to heat the one or at least one of the several distillation columns using heat.

The proposed plant comprises a heating system with one or more heat pumps and one or more heat storage units and is designed to provide at least part of the heat using the heating system and to supply heat generated in the process to the heating system.

For further features and advantages of a corresponding system and embodiments thereof, express reference is made to the above explanations concerning the method proposed according to the invention and its embodiments, since these apply to this in the same way.

The same applies to a system which, according to an embodiment of the invention, is designed to carry out a method according to any embodiment of the present invention. Short description of the drawing

Embodiments of the invention are described below purely by way of example with reference to the accompanying drawings, in which

Figure 1 illustrates a method according to an embodiment of the invention, and

Figure 2 illustrates a method according to an embodiment of the invention.

embodiments of the invention

The embodiments described below are described solely for the purpose of assisting the reader in understanding the features claimed and discussed above. They are merely representative examples and are not intended to be exhaustive and/or limiting with respect to the features of the invention. It is to be understood that the advantages, embodiments, examples, functions, features, structures and/or other aspects described above and below are not to be considered as limitations on the scope of the invention as defined in the claims or as limitations on equivalents to the claims, and that other embodiments may be utilized and changes may be made without departing from the scope of the invention as claimed.

Different embodiments of the invention may include, have, consist of, or consist essentially of other useful combinations of the described elements, components, features, parts, steps, means, etc., even if such combinations are not specifically described herein.

Furthermore, the disclosure may cover other inventions which are not currently claimed but which may be claimed in the future, particularly if they are included within the scope of the independent claims.

Explanations relating to devices, apparatus, arrangements, systems, etc. according to embodiments of the present invention may also apply to methods, processes, methods, etc. according to embodiments of the present invention and vice versa. Identical, equivalent, functionally identical Corresponding, structurally identical or comparable elements, process steps, etc. can be indicated with identical reference symbols.

As already mentioned, according to embodiments of the present invention, it is proposed to use heat pumps in combination with thermal energy storage devices to provide at least part of the heat required for the purification of one or more liquid components produced in a methanol reactor, but the present invention is not limited to methanol synthesis or certain electrolysis processes.

Against this background, Figure 1 shows a process for producing methanol according to an embodiment of the present invention. The process shown, designated 100 in total, can be understood as a so-called "power-to-methanol" process. It works on the basis of PEM electrolysis.

In the process 100, a water stream 1 is fed to a first purification stage 101, then combined with a recyclate stream 2, cooled in a heat exchanger referred to here for the sake of clarity as an electrolysis water heat exchanger 102, further purified in a second purification stage 103 and fed to the PEM electrolysis 104, i.e. a corresponding electrolysis stack of a known type.

A cathode stream 3 taken from the PEM electrolysis 104 is phase-separated in a phase separator 105 to obtain a hydrogen-rich gas stream 4, which is subjected to a hydrogen purification 106 and then compressed to a suitable pressure level using a compressor 107 to obtain a corresponding compressed gas stream 5.

An anode stream 6 taken from the PEM electrolysis stack is phase-separated in a phase separator 108 to obtain an oxygen-rich gas stream 7, wherein, as shown in the form of a dash-dotted line, a portion of this can be fed to a carbon dioxide purification unit 109 supplied with a carbon dioxide stream 9 and the remainder can be used for other purposes or blown off. The aqueous liquid phases separated in the phase separators 105 and 108 can be combined to form the recyclate stream 2 and transported back to the point of union with the water stream 1 by means of a pump 110.

A carbon dioxide stream 10 purified in the carbon dioxide purification unit 109 is combined downstream of the compressor 107 with the hydrogen-rich stream 5 to form a collecting stream 11 to which a recyclate stream 12 is fed, thereby forming a reaction feed stream 13.

The reaction feed stream 13 is heated in a feed effluent heat exchanger 111 and a heater 112 and fed into a tempered methanol reactor 113. A product stream 32 withdrawn from the methanol reactor 113, which may contain methanol, water, fusel oils and unreacted reactants, is passed through the feed effluent heat exchanger 111, then cooled in a heat exchanger 114 and in coolers of any type, referred to below essentially for the sake of clarity as process gas coolers 115 and 116, and then fed into a phase separator 117, in which methanol, water and the fusel oils as well as a portion of the unreacted reactants separate into the liquid phase and a further portion of the unreacted reactants remain in the gas phase.

A corresponding gas stream 14 is withdrawn from the top of the phase separator 117, which - minus a flushing or purge gas stream 15 to remove inert components and to prevent their accumulation - is compressed by means of a compressor 118 and used as the recyclate stream 12. A liquid stream 16 with the mentioned components is withdrawn from the bottom of the phase separator 117 and is expanded into a further phase separator 120 by means of a valve 119. Due to the expansion (flashing), some of the components dissolved in the liquid phase pass into the gas phase.

A gas stream 17 is withdrawn from the top of the phase separator 120 and is combined with another gas stream 18 to form an off-gas stream 19. A liquid stream 20 is withdrawn from the bottom of the phase separator 120 and fed by means of a valve 121 into a distillation column 122 which is connected to a top condenser 123 and a bottom evaporator 124 in a manner known per se from distillation or rectification technology.

In addition to the gas stream 18, a methanol stream 21 and a fusel oil stream 22 as well as a waste water stream 23 are withdrawn from the distillation column 122 via corresponding side withdrawals.

The dotted lines in Figure 1 represent the possible heat sources that can be used to operate the bottom evaporator 124 of the distillation column 122. In the example shown, a heat pump 201, which is in exchange with a heat storage unit 202, and an electric heater 203 are provided. A corresponding system is referred to here as a heating system and is indicated with the reference number 210. A steam system is indicated with 204.

If there are no additional external steam consumers, preferably all of the steam that is generated from the heat released during the exothermic reaction in the reactor 113 is used to heat the distillation column 122, i.e. its bottom evaporator 124. The steam system 204 is designed in particular to remove heat from the heat exchanger 114 via corresponding water or steam streams 24 and to feed it in any form, as shown by line 25, into the system comprising the heat pump 201 and the heat storage unit 202.

As already described, in the direct hydrogenation of carbon dioxide, this heat 25 alone may not be sufficient to operate the distillation column 122, i.e. its bottom evaporator 124. Additional heat can be obtained by using the heat pump 201, which can obtain heat 26 from the electrolysis water heat exchanger 102, heat 27 from the process gas coolers 115 and 116 upstream of the phase separator 117 in the circuit, as well as heat 28 from the top condenser 12 and heat 29 from the electric heater 203. The heater 203 can also directly provide electrically generated heat 30 to the bottom evaporator 124. The connection between the heat pump 201 and the heat storage unit 202 is clear from Figure 1. Figure 2 shows a process for producing methanol according to a further embodiment of the present invention. The process shown is designated as a whole by 200. The process shown here can also be understood as a so-called "power-to-methanol" process. In contrast to the process 100, it works on the basis of high-temperature electrolysis 150.

A water stream 1, designated 1 above and appropriately treated if necessary, is fed to the high-temperature electrolysis 150. The high-temperature electrolysis 150 already contains the so-called "balance of plant", i.e. water purification, a phase separator and water circuit (at least on the cathode side) and heat integration (e.g. with preheater, evaporator and superheater). In contrast to the PEM electrolysis 104 Figure 1, the high-temperature electrolysis 150 is thus shown here as a black box.

A hydrogen-rich stream formed in the high-temperature electrolysis 150 is partially compressed using a compressor 107a to form a partially compressed hydrogen-rich stream 4, which is then fed to a hydrogen purification plant as designated above with 106. A hydrogen stream obtained there in a purified form is finally compressed in a compressor 107b, whereby a hydrogen stream can be obtained which can essentially correspond to the hydrogen stream 5 according to Figure 1 in terms of composition, pressure and/or temperature and is therefore also designated with 5 in Figure 2.

The hydrogen stream 5 and a carbon dioxide stream 10 from a carbon dioxide purification unit 109, which is supplied here with an externally provided oxygen stream 8, can also be combined here to form a collective stream 11, which can be further processed in the same, essentially the same or comparable manner as explained for Figure 1. Reference is made to the above explanations.

As illustrated in Figure 2, heat 26a dissipated in the compressor 107a in particular can be used in the system comprising heat pump 201 and heat storage unit 202. As also illustrated, a portion 25a of the heat from the steam system 204 can be used in the high-temperature electrolysis 150. In both combinations, ie the methods 100 and 200 according to Figures 1 and 2, the heat storage unit 202 is filled, as illustrated by arrow 31, in particular with excess heat 25 from the reactor 113 and not with excess heat 26-28 or 26a from another source, since this heat 25 is readily available at a higher temperature level. The steam 24 generated by means of the reactor heat 25 can also be thermally upgraded for this purpose by using electricity or by combustion of exhaust gases. The heat storage unit 202 can also be charged with heat 29 from the electric heater 203, for example when electricity is available in high quantities.

As an alternative to a classic closed-loop heat pump, steam compression can be used to couple the top condenser 123 and bottom evaporator 124 of the distillation column 122. Since no additional steam is generated in this case, the heat storage unit 202 will then advantageously be charged with steam 24 from the steam system 204.

The same possibilities for heat integration as in the PEM electrolysis used in Figure 1 or method 100 arise in an alkaline water electrolysis. In the case of the high-temperature electrolysis 150 according to Figure 2 or method 200, this represents an additional steam consumer. While a portion of the steam used in the high-temperature electrolysis 150 is normally generated internally by heat integration, the available process heat within the high-temperature electrolysis 150 is typically not sufficient to cover the steam requirement.

The remaining demand can be covered by the reactor steam or corresponding heat, as shown at 25a. Alternatively, steam-generating heat pumps 201 can generate steam at a pressure suitable for the high-temperature electrolysis 150. Since the high-temperature electrolysis 150 takes place at lower pressures than the PEM electrolysis 104, the multi-stage arrangement of the compressors 107a and 107b is used. The heat from the intercoolers (not shown separately) can be used for the sump evaporator 124 after being upgraded with the heat pump 201. When discharging the heat storage unit 202, provision can be made in particular to use the heat released for the heat consumer with the lowest temperature, ie for the sump evaporator 124.

In both cases, i.e., the methods 100 and 200 illustrated in Figure 1 and Figure 2, the steam extracted from the heat storage unit 202 may be upgraded with the steam compressor (not illustrated) of the heat pump 201, if present. When the steam generator of the heat pump 201 produces less steam, the steam compressor may be operated closer to its optimal operating point by the additional supply of low quality steam from the heat storage unit 202.

Table 1 below shows the steady state heat flows for a specific plant configuration at full load.

It is assumed that in the cases of high-temperature electrolysis 150, all of the steam 25 or corresponding heat 25a generated in the reactor 113 is used for the high-temperature electrolysis 150. The values in the “reactor steam” column, which indicates the heat available for the distillation column 122 or its bottom evaporator 124, are therefore zero. An additional electric heater 203 is required to cover the heat requirement of the bottom evaporator 124. The specified power requirement in the “Electrical energy” column includes the power requirement for the heat pump 201 and the electric heater 203.

For the PEM electrolysis 104, it is assumed that the entire reactor steam is used to operate the sump evaporator 124. The values in the “Reactor steam” column are calculated accordingly. Accordingly, the required heat pump output is significantly lower than in the case of the high-temperature electrolysis 150. An electric heater 203 is only required if steam compression is used, which explains the corresponding values in the “Electrical energy” column.

In the two cases where a closed loop heat pump 201 is used, the heat supplied to the sump evaporator 124 is a combination of heat from the heat source and from the heat pump 201 used electricity, whereby the ratio depends in particular on a coefficient of performance (COP) of the heat pump 201.

With regard to the steady-state efficiency, the cases with steam compression are particularly advantageous. It should be noted that in both cases of steam compression at least part of the heat comes from the reactor 113 and/or the electric heater 203, i.e. this heat can be stored and/or provided flexibly.

When using PEM electrolysis 104, the alternatives with closed-loop heat pumps 201 are only slightly less efficient at the assumed coefficient of performance. The heat from the process gas coolers 115 and 116, which is indicated in the "Heat source" column, can be considered free of charge, since it would otherwise be released into the environment.

When using high-temperature or solid oxide electrolysis 150, the discrepancy between vapor compression and cycle heat pumps is greater, since a heat pump 201 that uses the heat from the compressor 107a or the process gas, i.e. the process gas coolers 115, 116, is not sufficient to supply enough heat for the sump evaporator 124, and therefore an electric heater 203 may have to be used.

Although installing two heat pumps 201 using the two heat sources would solve this problem, it might increase the complexity of the system and the investment costs. Nevertheless, embodiments of the present invention may also extend to such a combination.

A particular advantage of the invention and its embodiments is that the temporary decoupling of the heat integration enables the decoupling of the column load from the total load for the process. This is particularly advantageous for the supply of green hydrogen.

In combination with an optional raw methanol tank located between the low pressure separator, i.e. the phase separator 121, and the distillation column 122, the invention enables the operation of the distillation column 122 with a lower load while the rest of the process operates with a high load, and with a higher load while the rest of the process operates with a low load.

This makes it possible to reduce the investment costs of the distillation column 122 and to operate it closer to its optimum operating point than without the invention and its correspondingly explained embodiments.

Table 1

Claims

patent claims 1. Process (100, 200) for producing a process product, wherein hydrogen is provided using water electrolysis (104, 150), wherein the hydrogen or a portion thereof is subjected to an exothermic reaction with carbon dioxide to release heat and obtain a product mixture containing the process product, wherein the product mixture or a portion thereof is subjected to distillation using one or more distillation columns (122), and wherein the one or at least one of the plurality of distillation columns (122) is heated using heat, characterized in that at least a portion of the heat is provided using a heating system (210) which comprises one or more heat pumps (201) and one or more heat storage units (202), and to which heat generated in the process (100, 200) is supplied. 2. The method (100, 200) according to claim 1, wherein the heat released in the exothermic reaction is used to a first extent to generate steam in a steam system (204) and a second extent is removed downstream thereof in one or more process gas heat exchangers (115, 116). 3. The method (100, 200) of claim 2, wherein the heat generated in the method (100, 200) and supplied to the heating system (210) comprises at least a portion of the heat removed in the one or more process gas heat exchangers (115, 116). 4. The method (100) according to claim 2 or 3, wherein the water electrolysis (104) is carried out as low-temperature electrolysis or comprises low-temperature electrolysis. 5. The method (100) of claim 4, wherein the low temperature electrolysis comprises proton exchange membrane electrolysis, anion exchange membrane electrolysis and/or alkaline electrolysis. 6. The method (100) according to claim 4 or 5, wherein electrolysis water is supplied to the low-temperature electrolysis, to which heat is added in an electrolysis water heat exchanger (102), and wherein the heat generated in the process (100) which is supplied to the heating system (210) comprises at least a portion of the heat extracted from the electrolysis water in the electrolysis water heat exchanger (102). 7. The method of any one of claims 4 to 6, wherein the heat generated in the method (100) that is supplied to the heating system (210) comprises heat from the steam generated in the steam system (204). 8. The method (200) according to any one of claims 2 to 7, wherein the water electrolysis (150) is carried out as high-temperature electrolysis or comprises high-temperature electrolysis. 9. The method (200) of claim 8, wherein the high temperature electrolysis comprises solid oxide electrolysis. 10. The method (200) according to claim 8 or 9, wherein a hydrogen-rich stream is taken from the high-temperature electrolysis, which is subjected to compression with the release of compression heat, and wherein the heat generated in the method (200) which is supplied to the heating system (210) comprises at least a portion of the compression heat. 1 1. The method (200) according to any one of claims 8 to 10, wherein the high temperature electrolysis is carried out using heat which comprises heat of the steam generated in the steam system (204) or a portion thereof, and wherein the heat generated in the method (200) which is supplied to the heating system (210) comprises only a portion or none of the heat of the steam generated in the steam system (204). 12. The method (100, 200) according to any one of the preceding claims, wherein the heating system (210) is operated using vapor compression and/or electric heating (203). 13. A process (100, 200) according to any one of the preceding claims, wherein methanol is produced as the process product. 14. Plant for producing a process product, which is designed to provide hydrogen using water electrolysis (104, 150), to subject the hydrogen or a portion thereof to an exothermic reaction with carbon dioxide to release heat and obtain a product mixture containing the process product, to subject the product mixture or a portion thereof to distillation using one or more distillation columns (122), and to heat one or at least one of the plurality of distillation columns (122) using heat, characterized in that the plant has a heating system with one or more heat pumps (201) and one or more heat storage units (202) and is designed to provide at least a portion of the heat using the heating system (210) and to supply heat arising in the process (100, 200) to the heating system (210). 15. System according to claim 14, which is set up to carry out a method (100, 200) according to one of claims 1 to 13.