Process and plant for producing a reaction product

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

[0001] Description

[0002] Process and plant for producing a reaction product

[0003] The present invention relates to a process and a plant for producing a reaction product, in particular methanol.

[0004] background

[0005] Currently, the production of methanol and its derivatives (e.g., dimethyl ether, DME) is mostly based on the reaction of synthesis gas containing carbon monoxide and hydrogen in a so-called methanol synthesis cycle. In conventional processes, these reactants typically originate from steam reforming or partial oxidation of carbonaceous (fossil) raw materials such as natural gas, liquid hydrocarbons, or coal.

[0006] 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:

[0007] 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 cofeed. The overall reaction taking place in such a cycle can be described by the reaction equation (1) given below.

[0008] CO2 + 3 H2CH3OH + H2O (1 )

[0009] The second route involves carbon dioxide electrolysis or co-electrolysis, by which at least a portion of the carbon dioxide input is converted to carbon monoxide, which is then fed into a cycle similar to the conventional methanol synthesis cycle. The overall reaction during the electrochemical conversion of carbon dioxide to carbon monoxide can be described by the reaction equation (2) given below.

[0010] CO + 2 H2— > CH3OH (2)

[0011] 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:

[0012] 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 combination. A correspondingly formed total feed stream is combined with a recycle stream, preheated, and reacted in one or more catalyst beds. The resulting product stream is cooled, the liquid reaction products are at least partially condensed and removed from the cycle, and the gaseous reactants are at least partially transferred to the aforementioned recycle stream. The liquid reaction products are purified, typically in one or two distillation columns.

[0013] Although the present invention is described below primarily with reference to methanol synthesis, and this may represent a particularly advantageous field of application of the invention and its embodiments, the present invention and its embodiments are suitable not only for this purpose, but also, in principle, for other processes in which the advantages of the invention and its embodiments explained below can be realized. Examples of corresponding processes are mentioned below and generally include all processes in which distillation of liquid reaction products is carried out at a temperature above ambient temperature.

[0014] The present invention now aims to improve corresponding processes, in particular for the production of methanol, and in particular to make them more flexible and / or energy-efficient. Disclosure of the Invention

[0015] Against this background, a process and a plant for producing a process product with the respective features of the independent patent claims are proposed. Further embodiments are the subject of the dependent patent claims and the following description.

[0016] 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) are used to increase the temperature level of the heat so that it corresponds to the temperature level required by a purification system in use. Storing the thermal energy makes it possible to increase the operational flexibility of the system despite a high degree of heat integration.

[0017] As mentioned, the present invention and its embodiments are described using methanol synthesis as an example. 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 that 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 resulting crude products.

[0018] In corresponding processes, process reactants, in particular hydrogen, are advantageously provided by means of electrical energy, ie in particular by means of electrolysis, so that the basics of corresponding electrolysis processes will be briefly discussed below.

[0019] In conventional water electrolysis, an aqueous alkaline solution, typically potassium hydroxide, is used as the electrolyte (AEL, alkaline electrolysis). Electrolysis with a unipolar or bipolar electrode arrangement takes place at atmospheric pressure, or on an industrial scale, significantly higher. Recent 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 at the anode side. Electrolysis technologies using an anion exchange membrane (AEM) are also used.

[0020] The water electrolysis processes mentioned so far are low-temperature processes in which the water to be electrolyzed is in the liquid phase. So-called steam electrolysis is also used, which can also be carried out with alkaline electrolytes (i.e., AELs) with adapted membranes, such as polysulfone membranes, or using solid oxide electrolysis cells (SOECs). The latter include, in particular, doped zirconium dioxide or oxides of other rare earth elements, which become conductive at higher temperatures. These processes are also referred to below as high-temperature electrolysis.

[0021] The term "electrolysis" will be used below to encompass all of these processes. Low-temperature electrolysis (PEM, AEL, AEM) is particularly suitable for flexible operation, supporting the energy transition to renewable energies. All processes can be used within the scope of the present invention and corresponding embodiments, including in combination.

[0022] Industrial heat pumps enable the temperature level of a heat flow to be increased. Their operating principle is to transfer heat from a heat source to a working fluid at a low temperature level, increase the pressure of the working fluid, and then release the heat at a higher temperature level to a heat sink. The pressure increase can be achieved, for example, by an electrically driven compressor. Often, the working fluid is evaporated at the low temperature level and condensed at the high temperature level, although this is not absolutely necessary according to the general operating principle. Heat pumps are currently most commonly used for hot water production, e.g., in 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 fluid can be used directly or further processed, e.g., through steam compression.

[0023] 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 described previously, the procedure follows the same general principle.

[0024] Renewable energy sources such as wind and solar are difficult or impossible to plan in terms of availability, meaning their availability fluctuates over time. To ensure that 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 a chemical reaction and is often lossy and slow to deliver.

[0025] Storing thermal energy, on the other hand, is comparatively inexpensive and flexible. Its traditional disadvantage is that thermal energy cannot be easily converted into other forms of energy, such as electrical energy, with high efficiency. A simple and cost-effective way to store thermal energy is to store sensible heat or thermal energy in cement. The storage system 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.

[0026] Embodiments of the present invention enable particularly advantageous storage of thermal energy.

[0027] The upgrading of methanol from a methanol synthesis can have a significant

[0028] Require a large amount of heat. The direct hydrogenation of carbon dioxide is particularly attractive due to the lower formation of by-products and the greater sophistication of water electrolysis compared to carbon dioxide electrolysis. However, this route results in a less exothermic reaction than the conventional route and in a higher water content in the liquid discharged from the synthesis cycle. Therefore, the purification unit requires more heat for operation but has less heat available from the reaction. If high-temperature electrolysis is used in this context to provide the reactant hydrogen, the heat requirement increases further. Embodiments of the present invention solve this problem through the use of heat pumps.

[0029] The use of heat pumps to raise the temperature level of heat available from parts of the process is more efficient than generating heat purely electrically. 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 used only for load changes, such as start-up heaters. Embodiments of the invention also solve this problem by combining the respective proposed approaches.

[0030] 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 (PEMs) enable extremely flexible operation. However, large-scale chemical processes such as methanol synthesis exhibit much slower dynamics. A high degree of heat integration typically exacerbates this problem. For example, it significantly complicates the commissioning of such a plant. This problem is also solved by the use of the present invention.In the proposed process for producing a process product, which may in particular be methanol, hydrogen is provided using water electrolysis, wherein the hydrogen or a portion thereof is subjected to an exothermic reaction with carbon dioxide, releasing heat and obtaining 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, and wherein one or at least one of the plurality of distillation columns is heated using heat. At least a portion of the heat is provided using a heating system comprising one or more heat pumps and one or more heat storage units, to which heat generated in the process is supplied.With regard to the advantages that can be achieved here, explicit reference is made to the above explanations.

[0031] The heat released in the exothermic reaction can be used, firstly, to generate steam in a steam system, and secondly, dissipated downstream in one or more process gas heat exchangers. The heat components are generated at different temperature levels and can be used for specific purposes.

[0032] The heat generated in the process and supplied to the heating system can, in particular, comprise at least a portion of the heat 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.

[0033] In embodiments of the present invention, water electrolysis can be carried out as low-temperature electrolysis or comprise low-temperature electrolysis. As previously explained, this allows for particularly flexible operation and does not require any additional heat.

[0034] In embodiments of the invention, low-temperature electrolysis can

[0035] Proton exchange membrane electrolysis, anion exchange membrane electrolysis, and / or alkaline electrolysis. The present invention and its design can thus be implemented with a wide range of electrolysis options.

[0036] In embodiments of the invention, electrolysis water can be supplied to the low-temperature electrolysis process, from which heat is extracted in an electrolysis water heat exchanger. The heat generated in the process and supplied to the heating system includes at least a portion of the heat extracted from the electrolysis water in the electrolysis water heat exchanger. This enables advantageous use of the corresponding heat, which can be raised to a suitable temperature level, in particular by means of the heat pump(s).

[0037] The heat generated in the process, which is supplied to the heating system, can, in the case of low-temperature electrolysis, particularly comprise heat from the steam generated in the steam system. This heat can 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.

[0038] Additionally or alternatively, water electrolysis can be carried out as high-temperature electrolysis or include high-temperature electrolysis. As mentioned, this requires additional heat. High-temperature electrolysis can, in particular, be carried out as solid oxide electrolysis.

[0039] In embodiments of the invention, a hydrogen-rich stream can be extracted from the high-temperature electrolysis process and subjected to compression, releasing compression heat. The heat generated in the process and supplied to the heating system can comprise at least a portion of the compression heat. This heat can also be brought to a suitable temperature level by means of the heat pump(s).

[0040] In the process, the high-temperature electrolysis can be carried out, in particular, using heat that comprises the heat of the steam generated in the steam system or a portion thereof, whereby the heat generated in the process and supplied to the heating system comprises only a portion of, 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.

[0041] In embodiments of the invention, the heating system can be operated using vapor compression and / or electric heating, with reference to the explanations below for further details.

[0042] As mentioned, methanol, in particular, can be produced as the product in the process. Other processes and the resulting products are explained above.

[0043] 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 plurality of distillation columns using heat.

[0044] 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.

[0045] For further features and advantages of a corresponding system and embodiments thereof, reference is expressly made to the above explanations concerning the method proposed according to the invention and its embodiments, since these apply equally to this.

[0046] The same applies to a system that, according to one embodiment of the invention, is configured to carry out a method according to any embodiment of the present invention. Brief description of the drawing

[0047] Embodiments of the invention are described below purely by way of example with reference to the accompanying drawings, in which

[0048] Figure 1 illustrates a method according to an embodiment of the invention, and

[0049] Figure 2 illustrates a method according to an embodiment of the invention.

[0050] Embodiments of the invention

[0051] The embodiments described below are described solely for the purpose of assisting the reader in understanding the claimed and previously discussed features. They are merely representative examples and are not intended to be exhaustive and / or limiting with regard 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 claimed invention.

[0052] 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.

[0053] 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.

[0054] 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 the embodiments of the present invention, and vice versa. Elements, method steps, etc. that are identical, have the same effect, are functionally equivalent, are structurally identical, or are comparable may be identified by identical reference numerals.

[0055] 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 specific electrolysis processes.

[0056] Against this background, Figure 1 shows a process for producing methanol according to one embodiment of the present invention. The process shown, designated 100 overall, can be considered a so-called "power-to-methanol" process. It operates on the basis of PEM electrolysis.

[0057] 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 electrolysis water heat exchanger 102, further purified in a second purification stage 103 and fed to the PEM electrolysis 104, ie a corresponding electrolysis stack of a known type.

[0058] 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.

[0059] 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. As shown in the form of a dot-dash 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 pumped back to the point of merging with the water stream 1 by means of a pump 110.

[0060] 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 collection stream 11, to which a recyclate stream 12 is fed, thereby forming a reaction feed stream 13.

[0061] The reaction feed stream 13 is heated in a feed-effluent heat exchanger 111 and a heater 112 and fed into a temperature-controlled 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 any type of cooler, referred to below essentially as process gas coolers 115 and 116 for the sake of clarity, 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, while another portion of the unreacted reactants remains in the gas phase.

[0062] A corresponding gas stream 14 is withdrawn from the top of phase separator 117, which—minus a purge gas stream 15 for removing inert components and preventing their accumulation—is compressed by a compressor 118 and used as the recycle stream 12. A liquid stream 16 containing the aforementioned components is withdrawn from the bottom of phase separator 117 and expanded into another phase separator 120 via a valve 119. Due to the expansion (flashing), a portion of the components dissolved in the liquid phase passes into the gas phase.

[0063] A gas stream 17 is withdrawn from the top of the phase separator 120 and 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 via a valve 121 into a distillation column 122, which is operated with a top condenser 123 and a bottom evaporator 124 in a manner known per se from distillation or rectification technology.

[0064] In addition to the gas stream 18, a methanol stream 21 and a fusel oil stream 22 are withdrawn from the distillation column 122 via corresponding side withdrawals, as well as a wastewater stream 23 from the sump.

[0065] 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 communicates 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 by reference numeral 210. A steam system is indicated by 204.

[0066] If no additional external steam consumers are present, preferably all of the steam generated from the heat released during the exothermic reaction in reactor 113 is used to heat distillation column 122, i.e., its bottom evaporator 124. Steam system 204 is particularly configured to remove heat from heat exchanger 114 via corresponding water or steam streams 24 and to feed it in any desired form, as shown by line 25, into the system comprising heat pump 201 and heat storage unit 202.

[0067] 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 through the use of 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 shown directly in Figure 1. Figure 2 shows a process for producing methanol according to a further embodiment of the present invention. The procedure shown is labeled 200 in total.The process presented here can also be considered a so-called "power-to-methanol" process. Unlike process 100, it operates on the basis of high-temperature electrolysis 150.

[0068] A water stream 1, designated 1 above and possibly appropriately treated, is fed to the high-temperature electrolysis unit 150. The high-temperature electrolysis unit 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 a preheater, evaporator, and superheater). In contrast to the PEM electrolysis unit 104 shown in Figure 1, the high-temperature electrolysis unit 150 is thus represented as a black box.

[0069] 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 unit, as designated above by 106. A purified hydrogen stream obtained there is finally compressed in a compressor 107b, whereby a hydrogen stream can be obtained which, in terms of composition, pressure, and / or temperature, can essentially correspond to the hydrogen stream 5 according to Figure 1 and is therefore also designated by 5 in Figure 2.

[0070] 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, substantially the same, or comparable manner as explained for Figure 1. Reference is made to the above explanations.

[0071] As illustrated in Figure 2, heat 26a dissipated in particular in the compressor 107a 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, i.e., the processes 100 and 200 according to Figures 1 and 2, the heat storage unit 202, as illustrated by arrow 31, is filled 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 through the use of electricity or through the 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 highly available.

[0072] As an alternative to a conventional closed-loop heat pump, vapor compression can be used to couple the top condenser 123 and the 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.

[0073] The same heat integration possibilities as in the PEM electrolysis used in Figure 1 or method 100 arise in 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 through heat integration, the available process heat within the high-temperature electrolysis 150 is typically insufficient to cover the steam demand.

[0074] 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 comprising the compressors 107a and 107b is used. The heat from the intercoolers (not shown separately) can be used for the bottom evaporator 124 after being upgraded by the heat pump 201. During the discharge of the heat storage unit 202, provision can be made, in particular, to use the heat released for the heat consumer with the lowest temperature, i.e., for the bottom evaporator 124.

[0075] In both cases, i.e., the methods 100 and 200 illustrated in Figures 1 and 2, the steam extracted from the heat storage unit 202 can be upgraded using 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 can be operated closer to its optimal operating point by additionally supplying low-quality steam from the heat storage unit 202.

[0076] Table 1 below shows the steady state heat flows for a specific plant configuration at full load.

[0077] It is assumed that in the case 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 demand of the bottom evaporator 124. The power demand specified in the "Electrical Energy" column includes the power demand for the heat pump 201 and the electric heater 203.

[0078] For PEM electrolysis 104, it is assumed that all of the reactor steam is used to operate the bottom evaporator 124. The values ​​in the "Reactor Steam" column are calculated accordingly. Accordingly, the required heat pump power is significantly lower than in the case of 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.

[0079] In both 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 electricity used by the heat pump 201, the ratio depending in particular on a coefficient of performance (COP) of the heat pump 201.

[0080] With regard to steady-state efficiency, the cases involving steam compression are particularly advantageous. It should be noted that in both cases of steam compression, at least part of the heat originates from the reactor 113 and / or the electric heater 203, meaning this heat can be stored and / or provided flexibly.

[0081] When using PEM electrolysis 104, the alternatives using closed-loop heat pumps 201 are only slightly less efficient at the assumed coefficient of performance. The heat from process gas coolers 115 and 116, which is indicated in the "Heat Source" column, can be considered free, as it would otherwise be released into the environment.

[0082] When using a 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, ie the process gas coolers 115, 116, is not sufficient to supply enough heat for the bottom evaporator 124, and therefore an electric heater 203 may have to be used.

[0083] While installing two heat pumps 201 utilizing 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.

[0084] A particular advantage of the invention and its embodiments is that the temporary decoupling of heat integration allows the column load to be decoupled from the overall process load. This is particularly advantageous for the supply of green hydrogen.

[0085] In combination with an optional crude methanol tank located between the low-pressure separator, i.e., the phase separator 121, and the distillation column 122, the invention enables the distillation column 122 to be operated at a lower load while the rest of the process operates at a high load, and at a higher load while the rest of the process operates at a low load.

[0086] This makes it possible to reduce the investment costs of the distillation column 122 and to operate it closer to its optimal operating point than without the invention and its correspondingly explained embodiments.

[0087] Table 1

Claims

Patent claims 1. A 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 according to any one of claims 4 to 6, wherein the heat generated in the method (100) which is supplied to the heating system (210) comprises heat of 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 stream 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 comprising heat of the steam generated in the steam system (204) or a portion thereof, and wherein the heat generated in the method (200) and supplied to the heating system (210) comprises only a portion or no 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 accumulating in the process (100, 200) to the heating system (210).

15. Plant according to claim 14, which is arranged to carry out a method (100, 200) according to one of claims 1 to 13.

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