Method for producing a hydrocarbon stream

Abstract

The present invention relates to a method for producing hydrocarbons and to a plant (1) for carrying out the method. The method comprises the steps of: carrying out (S10) an endothermic first reaction process, in the form of a reverse water-gas shift (RWGS) reaction, at a first temperature (T1) using a CO2 reactant stream (10) and an H2 reactant stream (12), in order to generate a first intermediate product stream (14) comprising a first CO mass flow (14); carrying out (S20) an exothermic second reaction process, in the form of a Fischer-Tropsch (FT) reaction, at a second temperature (T2) using a the first CO mass flow (14) and an additional H2 reactant stream (16), in order to generate a hydrocarbon stream (18); removing (S30) process heat (20a-d) from the second reaction process; and feeding (S40) a first portion (20a) of the process heat (20a-d) to the first reaction process in the form of a first heat flow (20a). The plant (1) is designed to carry out the method.

Description

[0001] Description

[0002] Process for producing a hydrocarbon stream

[0003] The present invention relates to a process for producing hydrocarbons and a plant for carrying out the process.

[0004] To produce renewable hydrocarbon products, especially renewably produced fuels such as gasoline, diesel, and kerosene, it is known to first generate hydrogen by electrolysis using renewably generated electricity. The hydrogen is then reacted with a carbon-containing reactant to form hydrocarbon products. The target product, gasoline, typically comprises C5 to C10 hydrocarbons, and kerosene preferably comprises C9 to C18 hydrocarbons. Known production processes include, for example, the methanol route and the Fischer-Tropsch route, hereinafter referred to as the "FT route" and "FT synthesis," respectively.

[0005] FT synthesis is characterized by a high level of technical maturity. For example, kerosene produced by FT synthesis has ASTM certification. However, the FT route is particularly energy-intensive, as outlined below.

[0006] When the FT reaction is cobalt-catalyzed, the reactants are carbon monoxide, CO, and hydrogen, H2, which are converted exothermically to the products hydrocarbon chains, (CH2)n, and water, H20. Typically, the FT synthesis is carried out at a maximum of 350 °C, since higher temperatures result in the formation of short-chain hydrocarbons, particularly C2 to C4 hydrocarbons, which are considered undesirable in the target fuel product.

[0007] The reactant CO can be produced in an upstream step from carbon dioxide, CO2, for example in the form of the so-called reverse water gas shift reaction, hereinafter "RWGS reaction" within the following equilibrium reaction: CO2 + H2CO + H2O. Since the desired RWGS reaction is endothermic, the equilibrium lies at high temperatures of approx. 800 °C or 900 °C on the side of the desired products CO and H2O.

[0008] At medium temperatures of approximately 500 °C or 600 °C, undesirable methane formation increases. At low temperatures below approximately 300 °C, the undesirable water-gas shift reaction, or "WGS reaction," dominates instead of the desired RWGS reaction, resulting in increased CO2 and H2 formation, which is undesirable.

[0009] Due to the large temperature difference of at least 450 °C between the endothermic RWGS reaction (typical reaction temperature of min. 800 °C) and the exothermic FT reaction (typical reaction temperature of max. 350 °C), heat transfer from the exothermic to the endothermic process is not feasible in conventional processes. In conventional processes, the heat for the RWGS reaction is provided by electrical heating or by combustion of H2 or CO with the addition of O2. Thus, the conventional FT route is particularly energy-intensive.

[0010] Starting from the known prior art, it is an object of the present invention to provide an improved process for producing hydrocarbons and a corresponding plant for carrying out the improved process.

[0011] The object is achieved by a method for producing hydrocarbons having the features of claim 1. Advantageous further developments emerge from the subclaims, the description, and the figures.

[0012] Accordingly, a process for producing hydrocarbons is proposed, comprising the following steps: - carrying out an endothermic first reaction process in the form of a reverse water gas shift (hereinafter abbreviated to "RWGS") reaction, at a first temperature using a GO2 reactant stream and a H2 reactant stream, in order to produce a first intermediate product stream comprising a first CO mass flow;

[0013] - carrying out an exothermic second reaction process, in the form of a Fischer-Tropsch (hereinafter abbreviated to "FT") reaction, at a second temperature using the first CO mass flow and a further H2 reactant flow to produce a hydrocarbon stream;

[0014] - Extraction of process heat from the second reaction process; and

[0015] - Supplying a first portion of the process heat to the first reaction process in the form of a first heat flow.

[0016] In other words, process heat is transferred from the exothermic to the endothermic reaction process by means of the first heat flow. This allows the energy balance of the process to be improved. For example, additional heating power for the endothermic reaction process can be eliminated or significantly reduced compared to the conventional process. Furthermore, combustion of the H2 provided as a reactant to provide heating power can be dispensed with.

[0017] The supply of process heat to a reaction process in the form of a heat flow includes the heating of a corresponding reactor as well as the heating of reactant streams of the reaction process.

[0018] The additional H2 reactant stream can be fed directly to the second reaction process as a separate reactant stream. Additionally or alternatively, the additional H2 reactant stream can be fed to the first reaction process, for example, together with the H2 reactant stream required for the RWGS reaction. In this case, an H2 excess can be present in the first reaction process, or in the corresponding RWGS reactor, whereby the H2 not consumed in the first reaction process can then provide the additional H2 reactant stream.

[0019] Whenever the first reaction process is mentioned below, this refers to the RWGS reaction process or the RWGS reaction or a corresponding RWGS reactor, and vice versa. Whenever the second reaction process is mentioned below, this refers to the FT reaction process or the FT reaction or a corresponding FT reactor, and vice versa.

[0020] In the course of the present invention it was recognized that a transfer of process heat from the FT reaction process to the RWGS reaction process is technically sensible and possible by deviating from the existing temperature paradigms with regard to the first temperature, i.e. an RWGS temperature of approx. 800 ° C, and the second temperature, i.e. an FT temperature of approx. 350 ° C. For example, the first temperature can be reduced by several fifty or hundreds of Kelvin compared to a conventional RWGS temperature of approx. 800 ° C. In conventional processes such a reduction of the RWGS temperature is dispensed with because at RWGS temperatures below 800 ° C increased CO2 is formed, which is considered disadvantageous because CO2 cannot be converted into the target products in the FT reactor and common FT catalysts are at least partially sensitive to CO2.In the course of the present invention it was surprisingly found that the advantage of process heat transfer can clearly outweigh these disadvantages .

[0021] Additionally or alternatively, the second temperature can be increased by several fifty or hundreds of Kelvin compared to a conventional FT temperature of approximately 350°C. In conventional processes, such an increase in the FT temperature is dispensed with because at FT temperatures above 350°C, increased formation of short hydrocarbon chains occurs, which is considered disadvantageous. In the course of the present invention, it was surprisingly found that the advantage of process heat transfer can significantly outweigh this disadvantage, and an energy saving of approximately 10% can be achieved compared to conventional processes.

[0022] According to a further development, the FT reaction process can be carried out using an iron catalyst and / or a cobalt catalyst. Thus, the second temperature can be easily adjusted to a desired temperature range.

[0023] According to a further development, the RWGS reaction process can be carried out using an RWGS catalyst designed to kinetically suppress methane formation occurring at the first temperature. In other words, the first temperature can be selected such that an unacceptable amount of methane would form in the RWGS reaction process, which is suppressed by the RWGS catalyst.

[0024] According to a further development, the first heat flow can have a third temperature, in particular before being fed to the first reaction process, the third temperature being at least 5 Kelvin higher than the first temperature. In particular, the third temperature can be at least a difference value d higher than the first temperature, the difference value d being in the range 5 to 100 Kelvin, in particular in the range 5 to 50 Kelvin, and furthermore in the range 10 to 30 Kelvin. Because the third temperature is higher than the first temperature, heat can be supplied to the endothermic first reaction process. It has been recognized that a difference value of d = 5 Kelvin is already sufficient to significantly improve the overall balance of the process compared to conventional processes.With increasing difference d, the desired heat transfer from the exothermic to the endothermic process can be improved. On the other hand, the reaction conditions in the first and / or second reaction process can shift, partially to the detriment of the typically desired products. Surprisingly, this supposedly disadvantageous shift can be more than compensated for by the proposed process thanks to the overall balance improvement.

[0025] The temperature adjustment of the RWGS temperature and the FT temperature or the difference value d proposed here can be provided in various ways, as explained below.

[0026] According to a second embodiment, the first temperature may be greater than or equal to the second temperature, wherein the method may comprise the following step:

[0027] - heating the first heat flow by means of a heat pump before feeding it to the first reaction process, in particular so that the first heat flow has the third temperature.

[0028] In particular, the temperature increase of the first heat flow can be achieved by means of the heat pump in such a way that the difference value d is achieved. For example, the first temperature can be 460 °C and the second temperature 450 °C, while the temperature increase can be approximately 20 Kelvin to essentially achieve the difference value of d = 10 Kelvin. In this way, sufficient heat energy can be transferred by means of process heat transfer to compensate for the aforementioned perceived disadvantages.

[0029] Furthermore, the first temperature can be between 300 ° C and 700 ° C. Alternatively, the first temperature can be between, for example, 400 ° C and 650 ° C or between 450 ° C and 600 ° C.

[0030] Additionally, the second temperature may be between 300 °C and 600 °C. Alternatively, the second temperature may be, for example, between 400 °C and 550 °C or between 450 °C and 520 °C. In this way, the first and second temperatures may be sufficiently close to each other to ensure efficient process heat transfer.

[0031] According to a third embodiment, which is an alternative to the second embodiment, the second temperature can be higher than the first temperature. Thus, for example, the use of a heat pump to increase the temperature of the first heat flow can be dispensed with. In other words, the process heat transfer can take place directly, i.e., without expending additional energy.

[0032] According to a further development, the second temperature can be at least 5 Kelvin higher than the first temperature. Alternatively, the second temperature can be, for example, at least 10 Kelvin or at least 20 Kelvin higher. In this way, sufficient heat energy can be transferred by means of the process heat transfer to compensate for the aforementioned perceived disadvantages.

[0033] According to a further development, the first temperature can be less than 800 ° C, in particular less than 600 ° C, and furthermore less than 500 ° C. Thus, a good compromise can be found between lowering the first temperature and increasing the second temperature, so that the benefit of the process heat transfer outweighs the aforementioned alleged disadvantages.

[0034] According to a further development, the step of "removing process heat from the FT reaction process" and / or the step of "supplying a first portion of the process heat to the RWGS reaction process in the form of a first heat flow" can be carried out using a heat transfer fluid, for example using steam and / or a molten salt as the heat transfer fluid. Thus, the process heat transfer can be carried out efficiently. Additionally or alternatively, a heat exchanger can be used. The embodiments and further developments described below are compatible with all other embodiments and further developments.

[0035] According to a further embodiment, the method may comprise the following steps:

[0036] - supplying a second portion of the extracted process heat to the first CO mass flow to carry out the FT reaction process; and / or

[0037] - Supplying a third portion of the extracted process heat to the further H2 reactant stream to carry out the FT reaction process.

[0038] According to a further embodiment, the method may comprise the following steps:

[0039] - separating a G02 mass flow from the first intermediate product stream of the RWGS reaction process; and

[0040] - Returning the separated G02 mass flow in the form of another G02 reactant flow to the RWGS reaction process.

[0041] Thus, the adverse effects of increased CO2 formation in the RWGS reaction process can be further mitigated or avoided at a second temperature below 800 °C. In particular, exposure of the FT catalysts to CO2 can be avoided.

[0042] According to a further embodiment, the method may comprise the following steps:

[0043] - separating the hydrocarbon stream into gaseous and liquid hydrocarbons, wherein the separated gaseous hydrocarbons have a chain length of not more than C4;

[0044] - Oligomerization of the previously separated, gaseous hydrocarbons;

[0045] - Feeding the previously produced oligomers to the hydrocarbon stream.

[0046] Alternatively, the separated gaseous hydrocarbons may have a chain length of at most C8 or at most C11. In particular, the separated gaseous hydrocarbons may be olefins. For example, a corresponding separation limit of O4 may be specified for gasoline as the target product, O8 for kerosene, and C11 for diesel.

[0047] By oligomerizing and subsequently feeding the resulting oligomers into the product stream of the FT reaction process, the disadvantages of a higher FT temperature compared to the conventional process can be efficiently compensated. In particular, the yield of the target product in the product-side hydrocarbon stream of the FT reaction process can be increased.

[0048] According to a further embodiment, the method may comprise the following steps:

[0049] - Separating short-chain gaseous components from the previously produced oligomers to generate an exhaust gas stream;

[0050] - feeding the exhaust gas stream into an exhaust gas combustion unit which is designed to provide process heat, and / or feeding the exhaust gas stream into an exhaust gas utilization unit.

[0051] In particular, short-chain gaseous components with a maximum chain length of C3 or C4 can be separated. This allows, on the one hand, the proportion of undesirable components in the feed of the produced oligomers to the hydrocarbon stream to be reduced. On the other hand, the undesirable components in the exhaust gas stream can be utilized to improve the overall balance.

[0052] According to a further embodiment, the method may comprise the following steps:

[0053] - Separation of high boilers; and

[0054] - Hydro-cracking of the high boilers in a hydro-cracker.

[0055] The high boilers to be separated off can in particular be in the form of waxes, for example waxes with a chain length of at least C20. The high boilers can be separated off in particular after the hydrocarbon stream has been separated into gaseous and liquid hydrocarbons, i.e. in particular the separated liquid hydrocarbons. Due to the proposed increase in the FT temperature, the hydrocarbon stream will contain fewer high boilers or waxes compared to the conventional process. This means that further energy can be saved in hydrocracking compared to the conventional process. In particular, the hydrocracker can be made much smaller, thus allowing considerable cost savings. At the same time, the target product yield can be increased by means of hydrocracking.

[0056] Alternatively, thanks to the relatively lower wax content resulting from the proposed increase in the FT temperature, high boiler removal and / or hydrocracking can be omitted, thus continuing to save investment costs and process energy compared to conventional processes. Alternatively, hydrocracking alone can be omitted, and the waxes can be separated, discharged, and marketed as a separate stream.

[0057] According to a further embodiment, the process can provide a closed loop for the utilization of by-products and / or exhaust gases and comprise the following steps:

[0058] - Discharge of target products, in particular fuel;

[0059] - Utilising the by-products, in particular naphtha, and / or exhaust gases, in particular by means of autothermal reforming (ATR) and / or by means of partial oxidation, to obtain a recycled synthesis gas, in particular comprising a mixture comprising CO, H2, CO2 and / or water; and

[0060] - feeding the recycled synthesis gas to the first reaction process so that the recycled by-products and / or off-gases are further processed in the process by means of the closed loop, and so that in particular the discharged target product is essentially the only hydrocarbon stream leaving the closed loop of the process.

[0061] The above-mentioned off-gases may include all off-gas streams obtainable in the process, in particular the off-gas stream separated from the oligomers produced.

[0062] Because the process can provide a closed loop for the utilization of the by-products and / or exhaust gases generated in the process, the costly regeneratively produced reactants CO2 and H2 can be significantly reduced. In particular, the utilization of the by-products can be achieved with only the additional use of readily available O2 and water. O2 can be provided particularly easily in the proposed process, for example, by using O2 from the required upstream water electrolysis, which always delivers H2 and O2 in a molar ratio of 2:1. In this way, the overall balance of the process can be further improved.

[0063] The above-mentioned object is further achieved by a system having the features of claim 16. Advantageous developments of the method will become apparent from the present description and the figures.

[0064] Accordingly, a plant is proposed which is designed to carry out the method described above.

[0065] According to a further development, the plant can have a first reactor, in particular in the form of an RWGS reactor, which is set up to carry out an endothermic first reaction process, in the form of a reverse water gas shift reaction, at a first temperature using a CO2 reactant stream and an H2 reactant stream in order to produce a first intermediate product stream comprising a first CO mass flow. Furthermore, the plant can have a second reactor, in particular in the form of an FT reactor, which is set up to carry out an exothermic second reaction process, in the form of a Fischer-Tropsch reaction, at a second temperature using the first CO mass flow and a further H2 reactant stream in order to produce a hydrocarbon stream.

[0066] Furthermore, the plant can have a heat transfer unit which is designed to extract process heat from the second reaction process and to supply a first portion of the process heat to the first reaction process in the form of a first heat flow.

[0067] Preferred further embodiments of the invention are explained in more detail in the following description of the figures. These schematically show:

[0068] Figure 1 is a flow diagram of a process for producing a hydrocarbon stream according to a first embodiment;

[0069] Figure 2 shows a flow diagram of the method according to a second embodiment;

[0070] Figure 3 is a flow chart of the method according to a third embodiment;

[0071] Figures 4, 5, 6 each show a flow diagram according to further embodiments of the method;

[0072] Figure 7 shows an embodiment of a plant for carrying out a process for producing a hydrocarbon stream; and

[0073] Figure 8 shows a further embodiment of the system for

[0074] Carrying out a method for producing a hydrocarbon stream. Preferred embodiments are described below with reference to the figures. Identical, similar, or equivalent elements in the different figures are provided with identical reference numerals, and a repeated description of these elements is partially omitted to avoid redundancies.

[0075] Figure 1 schematically shows a flow diagram of a process for producing a hydrocarbon stream according to a first embodiment. As can be seen from Figure 1 and Figure 7, the process comprises the following steps:

[0076] - Carrying out S 10 an endothermic RWGS reaction process at a first temperature TI , wherein a GO 2 reactant stream 10 and an H 2 reactant stream 12 are present on the reactant side. By means of the RWGS reaction process, a first intermediate product stream 14 comprising a first CO mass stream 14 is generated on the product side.

[0077] - Carrying out S20 an exothermic FT reaction process at a second temperature T2, wherein the first CO mass flow 14 and a further H2 reactant flow 16 are present on the reactant side. A hydrocarbon flow 18 is generated on the product side by means of the FT reaction process.

[0078] - Removal S30 of process heat 20a-d from the FT reaction process.

[0079] - Supplying S40 a first portion 20a of the process heat 20a-d to the RWGS reaction process in the form of a first heat flow 20a.

[0080] By transferring process heat from the exothermic to the endothermic reaction process by means of the first heat flow 20a, the energy balance of the process can be improved.

[0081] The product-side hydrocarbon stream 18 is also referred to as "syncrude" and is a hydrocarbon mixture comprising paraffins and olefins. In order to obtain a fuel as the main or target product, the resulting syncrude is further processed in a series of hydrogenation processes, which are described below.

[0082] Figure 2 shows a schematic flow diagram of the method according to a second embodiment, wherein the reaction conditions of the first and second reactions are designed such that the first temperature TI is greater than or equal to the second temperature T2. Furthermore, after the step S30 of removing process heat 20a-d from the FT reaction process, an additional step of heating S35 the first heat flow 20a by means of a heat pump 22 takes place before feeding S40 to the first reaction process, so that the first heat flow 20a experiences a temperature increase. A third temperature T3 of the first heat flow 20a heated by means of the heat pump 22 is at least 5 Kelvin higher than the first temperature TI.

[0083] The temperature difference between the first and second temperatures TI, T2 is to be limited in such a way, for example to a maximum of 100 K, alternatively a maximum of 50 K or a maximum of 30 K, that the heat pump 22 can be operated efficiently while at the same time a heat transfer from the exothermic to the endothermic reaction process can take place.

[0084] Figure 3 shows a schematic flow diagram of the method according to a third embodiment, wherein the reaction conditions of the first and second reaction processes are designed such that the second temperature T2 is greater than or equal to the first temperature TI. In this embodiment, the heat pump 22 can optionally be omitted. In one example, the second temperature T2 is at least approximately 5 Kelvin higher than the first temperature. In further examples, the second temperature T2 can be at least 10, 20, 30, 40 or over 50 Kelvin higher than the first temperature TI. Optionally, a heating step S35 by means of the heat pump 22 according to the second embodiment can also be carried out in the third embodiment. Figures 4, 5, 6 each schematically show a flow diagram according to further embodiments of the method.As can be seen in Figure 4 and further in Figure 8, in one exemplary embodiment, after step S 10, a separation S 12 of a CCp mass stream 24 from the first intermediate product stream 14 of the first reaction process takes place. Subsequently, the separated CCp mass stream 24 is recycled S 14 in the form of a further CCp reactant stream 24 to the first reaction process.

[0085] Additionally or alternatively to the above embodiment, after step S30, a second partial amount 20b of the extracted process heat 20a-d is fed S45 to the first CO mass flow 14 for carrying out S20 the second reaction process. Furthermore, after step S30, a third partial amount 20c of the extracted process heat 20a-d is fed S47 to the further H2 reactant flow 16 for carrying out S20 the second reaction process. As can be seen in Figure 8, after step S30, a fourth partial amount 20d of the extracted process heat 20a-d is fed S49 to a later step S100 for the HC separation into main and by-products, which can take place, for example, in a separation column 38 to be heated. The supply S49 of the fourth subset 20d can take place in the form of a fourth heat stream 20d for heating the separation column 38 and / or for preheating the reactants of the separation column.

[0086] As can be seen in Figure 5 and further in Figure 8, after step S20, according to a further exemplary embodiment, a separation S50 of the hydrocarbon stream 18, i.e. the product stream 18 of step S20, into gaseous and liquid HC components 26, 27 and the by-product water takes place. Step S50 can take place by means of a central separator. After step S50, an oligomerization S60 of the separated, gaseous hydrocarbons 26 takes place. Optionally, after step S60, a separation S65 of short-chain gaseous components takes place in order to provide an exhaust gas stream 30. After step S65, the exhaust gas stream 30 is fed to an exhaust gas combustion in order to provide further process heat, according to a step S67. Additionally or alternatively, the exhaust gas stream 30 is fed to a by-product utilization unit 32 or exhaust gas utilization unit 32 after step S 65 according to a step S 68.Furthermore, after the oligomerization S 60, the oligomers 29 produced are fed S70 to the product stream 18 from step S20.

[0087] As can be seen in Figure 6 and further in Figure 8, according to a further exemplary embodiment, a separation S80 of high boilers 34 takes place after step S50. The high boilers to be separated can be waxes 34 with a chain length of at least C20, alternatively at least C22, C24, or higher chain lengths. Subsequently, a hydrocracking S82 of the separated high boilers 34 takes place by means of a hydrocracker 35.

[0088] According to a further embodiment, after step S50 or after step S80, an isomerization and saturation S90 of the liquid HC fractions 27 takes place. Subsequently, in step S100, the liquid HC fractions 27 are separated into main and by-products, in particular naphtha 40, waxes 36 and further off-gases 39. The further off-gases

[0089] 39 can, for example, comprise compounds from methane to butane. Step S 100 can, for example, be carried out by means of a separation column 38 configured to separate the target product fraction from a naphtha fraction 40 and the waxes 36.

[0090] In a step S 102, a portion of the wax by-products 36 is fed to the hydrocracking according to step S 82. In a step S 104, the by-products, in particular naphtha

[0091] 40 and exhaust gas 39, are fed to the by-product utilization unit 32. Furthermore, the desired main products or target products, for example fuels 41, such as gasoline, kerosene or diesel, are obtained in step S 105. The exhaust gas utilization unit 32 can be included in the by-product utilization unit 32 or provided separately therefrom. The exhaust gases 30, 39 can be converted back into synthesis gas in the exhaust gas utilization unit 32 in a step S 106, for example by autothermal reforming (ATR) and / or by partial oxidation and can be provided again to the process, in particular to the first reaction, as a reactant in a step S 110. For example, a synthesis gas 42 obtained from the exhaust gas utilization can be a mixture of CO, H2, CO2 and water.By feeding the synthesis gas 42 to the first reaction (S 110), the basic building blocks of carbon and hydrogen are retained to a particularly high degree in the proposed process, thus further improving the overall yield. Furthermore, synthesis gas 42 can be generated from the naphtha fraction 40 by recycling.

[0092] Furthermore, the utilization processes in the exhaust gas utilization unit 32 or in the by-product utilization unit 32, in particular the partial or full oxidation, can be highly exothermic. Thus, the resulting process heat can be transferred and utilized analogously to the process heat 20a-d to heat individual process stages of the proposed method.

[0093] Figures 7 and 8 each schematically show an embodiment of a plant 1 for carrying out a process for producing a hydrocarbon stream and were explained above in connection with the description of Figures 1 to 6.

[0094] The process described is in principle capable of producing each of the target products in the form of fuels. The plant operator can therefore specify the conditions in the process units accordingly. For example, with increasing FT temperature, i.e. a high selected second temperature T2, for example T2 > 500 °C, and with increasing H2:CO reactant ratio, the proportion of shorter hydrocarbon chains increases at the expense of longer chains. The product spectrum thus shifts increasingly from long-chain waxes via diesel or kerosene as middle distillates to short-chain products such as naphtha, from which gasoline can be produced by hydrogenation processes. At very high FT temperatures, i.e. a very high selected second temperature T2, for example T2 > 650 °C, the product spectrum can even shift to short chains with lengths below C5.This short-chain fraction may be too light for the naphtha / gasoline and can be added to the other exhaust gases 39 in the HC separation according to step S 100.

[0095] Where applicable, all individual features presented in the exemplary embodiments can be combined and / or interchanged without departing from the scope of the invention. For example, the heat pump 22 and the corresponding step S35 can be used in any embodiment. Furthermore, for example, the high boiler removal according to step S80 and the hydrocracking S82 are optional, so that the isomerization and saturation S90 can take place immediately after step S20 or S50.

Claims

Patent claims 1. A process for producing a hydrocarbon stream comprising the following steps: - carrying out (S10) an endothermic first reaction process, in the form of a reverse water gas shift (RWGS) reaction, at a first temperature (TI) using a GO2 reactant stream (10) and an H2 reactant stream (12) to produce a first intermediate product stream (14) comprising a first CO mass stream (14); - carrying out (S20) an exothermic second reaction process, in the form of a Fischer-Tropsch (FT) reaction, at a second temperature (T2) using the first CO mass flow (14) and a further H2 reactant flow (16) to produce a hydrocarbon flow (18); - Extraction (S30) of process heat (20a-d) from the second reaction process; and - supplying (S40) a first partial quantity (20a) of the process heat (20a-d) to the first reaction process in the form of a first heat flow (20a).

2. The method according to claim 1, wherein the first heat flow (20a), in particular before being fed (S40) to the first reaction process (RWGS), has a third temperature (T3), wherein the third temperature (T3) is at least 5 K higher than the first temperature (TI), in particular wherein the third temperature (T3) is at least a difference value (d) higher than the first temperature (TI), wherein the difference value (d) is in the range 5 K to 100 K, in particular in the range 5 K to 50 K, furthermore in the range 10 K to 30 K.

3. The method according to claim 1 or 2, wherein the first temperature is greater than or equal to the second temperature, comprising the following step: - heating (S35) the first heat flow (20a) by means of a heat pump (22) before feeding (S40) to the first reaction process (RWGS), in particular so that the first heat flow (20a) has the third temperature (T3).

4. The method according to claim 1 to 3, wherein the first temperature is between 300 °C and 700 °C, in particular between 400 °C and 650 °C, furthermore between 450 °C and 600 °C, and wherein the second temperature is between 300 °C and 600 °C, in particular between 400 °C and 550 °C, furthermore between 450 °C and 520 °C.

5. The method according to claim 1 or 2, wherein the second temperature (T2) is greater than or equal to the first temperature (TI).

6. The method according to claim 5, wherein the second temperature (T2) is at least 5 K higher than the first temperature (TI), in particular at least 10 K, furthermore at least 20 K.

7. The method according to one of claims 5 or 6, wherein the first temperature (TI) is less than 800 °C, in particular less than 600 °C, furthermore less than 500 °C.

8. The method according to any one of claims 5 to 7, wherein the step of removing (S30) process heat (20a-d) from the first reaction process (RWGS) and / or the step of supplying (S40) a first partial quantity (20a) of the process heat (20a-d) to the first reaction process (RWGS) in the form of the first heat flow (20a) is carried out using a heat exchanger and / or a heat transfer fluid, in particular steam and / or a molten salt.

9. Method according to one of the preceding claims, comprising the following step - Supplying (S45) a second partial quantity (20b) of the extracted (S30) process heat (20a-d) to the first CO mass flow (14) for carrying out (S20) the second reaction process (FT).

10. Method according to one of the preceding claims, comprising the following step - feeding (S47) a third partial quantity (20c) of the extracted (S30) process heat (20a-d) to the further H2 reactant stream (16) for carrying out (S20) the second reaction process (FT).

11. Method according to one of the preceding claims, comprising the following steps: - separating (S12) a G02 mass flow (24) from the first intermediate product flow (14) of the first reaction process (RWGS); and - Returning (S14) the separated G02 mass flow (24) in the form of a further G02 reactant flow (24) to the first reaction process (RWGS).

12. Method according to one of the preceding claims, comprising the following steps: - separating (S50) the hydrocarbon stream (18) into gaseous (26), in particular olefins, and liquid (27) hydrocarbons, wherein the separated gaseous hydrocarbons (26) have a chain length of at most C4, at most C8 or at most C11; - oligomerization (S60) of the separated gaseous hydrocarbons (26); - feeding (S70) the produced oligomers (28) to the hydrocarbon stream (18).

13. Method according to one of the preceding claims, comprising the following steps: - separating (S65) short-chain gaseous components, in particular with a chain length of at most C3 or C4, from the oligomers (28) produced in order to produce an exhaust gas stream (30); - feeding (S67) the exhaust gas stream (30) into an exhaust gas combustion unit which is designed to provide process heat, and / or feeding (S68) the exhaust gas stream (30) into an exhaust gas utilization unit (32).

14. Method according to one of the preceding claims, comprising the following steps: - separating (S80) high boilers (34), in particular in the form of waxes with a chain length of at least C20; and - Hydro-cracking (S82) of the high boilers (34) in a hydro-cracker (35).

15. A process according to any one of the preceding claims, wherein the process provides a closed circuit for the utilization of by-products (40) and / or exhaust gases (30, 39) and comprises the following steps: Discharge (S105) of target products, in particular fuel (41); Utilization (S106) of by-products (40), especially naphtha (40) , and / or exhaust gases (30, 39), in particular by means of autothermal reforming (ATR) and / or by means of partial oxidation, in order to obtain a recycled synthesis gas (42), in particular comprising a mixture comprising CO, H2, CO2 and / or water; and Feeding (S110) the recycled synthesis gas (42) to the first reaction process (RWGS) so that the recycled (S106) by-products (40) and / or exhaust gases (30, 39) are further processed in the process by means of the closed circuit, and so that in particular the discharged (S105) target product (41) is essentially the only hydrocarbon stream leaving the closed loop of the process.

16. Plant (1) which is arranged to carry out the method according to one of the preceding claims.

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