Process for preparing a hydrocarbon stream
By adjusting the temperature in the RWGS and FT reactions and utilizing process heat transfer, the high energy consumption of the FT synthesis method was solved, achieving optimization of energy balance and improvement of the yield of the target product.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SIEMENS ENERGY GLOBAL GMBH & CO KG
- Filing Date
- 2024-07-19
- Publication Date
- 2026-06-02
AI Technical Summary
Existing FT synthesis methods are energy-intensive and have difficulty effectively transferring heat from the exothermic FT reaction to the endothermic RWGS reaction, resulting in an energy imbalance.
By conducting RWGS and FT reactions at different temperatures, and utilizing process heat to extract heat from the FT reaction process and transfer it to the RWGS reaction process, the reaction temperature is adjusted to match the heat transfer. Heat pumps or heat transfer fluids are used for heat transfer to optimize the reaction conditions.
It significantly reduces the additional heating power required for endothermic reactions, improves energy balance, reduces energy consumption, increases the yield of the target product, and saves on equipment investment costs.
Smart Images
Figure CN122139016A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for preparing hydrocarbons and an apparatus for performing the method. Background Technology
[0002] To prepare renewable hydrocarbon products, particularly renewable fuels such as gasoline, diesel, and kerosene, it is known to first produce hydrogen using renewable electricity through electrolysis. This hydrogen is then reacted with carbonaceous reaction partners, whereby hydrocarbon products are formed. The target product, gasoline, typically preferably contains C5 to C10 hydrocarbons, and kerosene preferably contains C9 to C18 hydrocarbons. Known preparation methods include, for example, the so-called methanol route and the so-called Fischer-Tropsch route (hereinafter referred to as the "FT route" or "FT synthesis").
[0003] The key feature of FT synthesis is its high level of technological sophistication. For example, ASTM certification exists for kerosene prepared via FT synthesis. However, as outlined below, the FT route is particularly energy-intensive.
[0004] When the FT reaction is carried out in a cobalt-catalyzed manner, the reactants are carbon monoxide (CO) and hydrogen (H2), which are exothermically converted into the products hydrocarbon chains ((CH2)n) and water (H2O). FT synthesis is typically performed at temperatures up to 350°C because at higher temperatures, more short-chain hydrocarbons, particularly C2 to C4 hydrocarbons, are formed, which are considered undesirable in fuel target products.
[0005] The reactant CO can be produced from carbon dioxide (CO2) in a previous step, for example, in the form of a so-called reverse water-gas shift reaction (hereinafter referred to as the "RWGS reaction"), which proceeds within the following equilibrium reaction: CO2 + H2 CO + H2O. Since the desired RWGS reaction is endothermic, the equilibrium is on the side of the desired products CO and H2O at a high temperature of about 800°C or 900°C.
[0006] At intermediate temperatures of around 500°C or 600°C, undesirable methane formation intensifies. At lower temperatures below approximately 300°C, the undesirable water-gas shift reaction (WGS reaction) dominates instead of the desired RWGS reaction, resulting in the formation of more CO2 and H2, which is undesirable.
[0007] Due to the significant temperature difference of at least 450°C between the endothermic RWGS reaction (typically a minimum reaction temperature of 800°C) and the exothermic FT reaction (typically a maximum reaction temperature of 350°C), heat transfer from the exothermic process to the endothermic process is impractical in conventional methods. In conventional methods, the heat for the RWGS reaction is provided by electric heating or by the combustion of H2 or CO in the presence of O2. Therefore, the conventional FT route is particularly energy-intensive. Summary of the Invention
[0008] Based on known prior art, the object of the present invention is to provide an improved method for preparing hydrocarbons and a corresponding apparatus for performing the improved method.
[0009] This objective is achieved by a method for preparing hydrocarbons having the features of claim 1. Advantageous improvements are derived from the dependent claims, the description, and the drawings.
[0010] Therefore, a method for preparing hydrocarbons is proposed, the method comprising the following steps: - An endothermic first reaction process is performed at a first temperature using a CO2 reactant stream and an H2 reactant stream in the form of a reverse water-gas shift (hereinafter abbreviated as "RWGS") reaction to produce a first intermediate product stream including a first CO mass stream; - In the form of a Fischer-Tropsch (hereinafter abbreviated as "FT") reaction, an exothermic second reaction process is performed at a second temperature using the first CO mass stream and another H2 reactant stream to produce a hydrocarbon stream; - Remove process heat from the second reaction process; and - A first portion of the process heat is supplied to the first reaction process in the form of a first heat flow.
[0011] In other words, process heat is transferred from the exothermic reaction process to the endothermic reaction process via this first heat flow. In this way, the energy balance of the method can be improved. For example, compared to conventional methods, the additional heating power required for the endothermic reaction process can be eliminated or significantly reduced. Furthermore, for example, the combustion of H2, which is used as a reactant, to provide heating power can be eliminated.
[0012] Supplying process heat to the reaction process in the form of a heat flow includes heating the corresponding reactor and heating the reaction stream of the reaction process.
[0013] The additional H2 reactant stream can be supplied directly to the second reaction process as a separate reactant stream. Alternatively or additionally, the additional H2 reactant stream may already be supplied to the first reaction process, for example, along with the H2 reactant stream required for the RWGS reaction. In this case, an H2 surplus may exist in the first reaction process, or in the corresponding RWGS reactor, where any H2 not consumed in the first reaction process can then be supplied as the additional H2 reactant stream.
[0014] If the first reaction process is referred to below, it refers to the RWGS reaction process or the RWGS reaction or the corresponding RWGS reactor, and vice versa. If the second reaction process is referred to below, it refers to the FT reaction process or the FT reaction or the corresponding FT reactor, and vice versa.
[0015] Within the scope of this invention, it has been recognized that it is technically reasonable and feasible to transfer process heat from an FT reaction process to an RWGS reaction process by deviating from the existing temperature paradigm regarding a first temperature (i.e., an RWGS temperature of approximately 800°C) and a second temperature (i.e., an FT temperature of approximately 350°C). For example, this first temperature can be reduced by several fifty or several hundred Kelvins compared to the conventional RWGS temperature of approximately 800°C. In conventional methods, this reduction in RWGS temperature is abandoned because more CO2 is formed below RWGS temperatures of 800°C, which is considered disadvantageous because CO2 cannot be converted to the target product in the FT reactor, and conventional FT catalysts are at least partially sensitive to CO2. Within the scope of this invention, it has been surprisingly found that the advantages of process heat transfer can significantly outweigh the aforementioned disadvantages.
[0016] Additionally or alternatively, this second temperature can be several fifty or several hundred Kelvin higher than the conventional FT temperature of approximately 350°C. In conventional methods, this increase in FT temperature is discarded because more short hydrocarbon chains are formed at FT temperatures above 350°C, which is considered disadvantageous. Within the scope of this invention, it has been surprisingly found that the advantages of process heat transfer can significantly outweigh this disadvantage, and energy savings of approximately 10% compared to conventional methods can be achieved.
[0017] According to an improved approach, the FT reaction process can be carried out using an iron catalyst and / or a cobalt catalyst. Therefore, the second temperature can be adjusted to the desired temperature range in a simple manner.
[0018] According to an improved approach, the RWGS reaction process can be carried out using an RWGS catalyst designed to kinetically suppress methane formation at a first temperature. In other words, the first temperature can be selected such that an unacceptable amount of methane would form during the RWGS reaction process, which is then suppressed by the RWGS catalyst.
[0019] According to an improved approach, the first heat flux, particularly before being supplied to the first reaction process, may have a third temperature, wherein the third temperature is at least 5 Kelvin higher than the first temperature. Specifically, the third temperature may be at least a difference d higher than the first temperature, wherein the difference d may be in the range of 5 to 100 Kelvin, particularly in the range of 5 to 50 Kelvin, and further in the range of 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 of d = 5 Kelvin is sufficient to significantly improve the overall balance of the method compared to conventional methods. With the increase of the difference d, on the one hand, the desired heat transfer from the exothermic process to the endothermic process can be improved; on the other hand, the reaction conditions in the first and / or second reaction processes will partially shift in a direction unfavorable to the normally desired products. Surprisingly, this seemingly unfavorable shift can be overcompensated by means of the proposed method due to the improvement in the overall balance.
[0020] The temperature matching or difference d between the RWGS temperature and the FT temperature proposed in this paper can be provided in various ways, as described below.
[0021] According to the second embodiment, the first temperature may be greater than or equal to the second temperature, wherein the method may include the following steps: - Before being supplied to the first reaction process, the first heat flow is heated by means of a heat pump, specifically so that the first heat flow has the third temperature.
[0022] Specifically, the first heat flow can be heated using the heat pump in such a way that the temperature difference d is achieved. For example, the first temperature can be 460°C and the second temperature can be 450°C, and the temperature rise can be approximately 20 Kelvin to achieve a temperature difference of approximately d = 10 Kelvin. In this way, sufficient heat energy can be transferred by process heat transfer to compensate for the seemingly disadvantageous drawbacks mentioned above.
[0023] Furthermore, the first temperature can be between 300°C and 700°C. Alternatively, the first temperature can be, for example, between 400°C and 650°C or between 450°C and 600°C.
[0024] Additionally, the second temperature can be between 300°C and 600°C. Alternatively, the second temperature can be, for example, between 400°C and 550°C or between 450°C and 520°C. In this way, the first temperature and the second temperature can be sufficiently close to or matched to each other to ensure effective process heat transfer.
[0025] According to the third embodiment (which replaces the second embodiment), the second temperature can be higher than the first temperature. Therefore, for example, it is possible to eliminate the need for a heat pump to raise the temperature of the first heat flow. In other words, the heat transfer process can proceed directly, without the need for additional energy.
[0026] According to one improvement, 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 process heat transfer to compensate for the aforementioned seemingly disadvantageous drawbacks.
[0027] According to one improvement, the first temperature can be less than 800°C, particularly less than 600°C, and further less than 500°C. Therefore, a good trade-off can be found between lowering the first temperature and raising the second temperature, so that the benefits of process heat transfer outweigh the seemingly disadvantageous drawbacks mentioned above.
[0028] According to an improved embodiment, the steps of "removing process heat from the FT reaction process" and / or "supplying a first portion of the process heat to the RWGS reaction process in the form of a first heat flow" can be performed using a heat transfer fluid, such as steam and / or salt melt. Therefore, the process heat transfer can be carried out efficiently. Additionally or alternatively, a heat exchanger can be used.
[0029] The implementation methods and improvements described below are compatible with all other implementation methods and improvements.
[0030] According to another implementation, the method may include the following steps: - A second portion of the extracted process heat is supplied to the first CO mass stream to perform the FT reaction process; and / or - A third portion of the extracted process heat is supplied to the other H2 reaction stream to perform the FT reaction process.
[0031] According to another implementation, the method may include the following steps: - Separate the CO2 mass stream from the first intermediate product stream of the RWGS reaction process; and - The separated CO2 mass stream is returned to the RWGS reaction process as another CO2 reactive stream.
[0032] Therefore, the adverse effects of increased CO2 formation in the RWGS reaction process at a second temperature below 800°C can be further mitigated or avoided. In particular, the FT catalyst can be protected from the effects of CO2.
[0033] According to another implementation, the method may include the following steps: - Separate the hydrocarbon stream into gaseous hydrocarbons and liquid hydrocarbons, wherein the separated gaseous hydrocarbons have a chain length of up to C4; - To cause the previously separated gaseous hydrocarbons to oligomerize; - Supply the previously generated oligomers to the hydrocarbon stream.
[0034] Alternatively, the separated gaseous hydrocarbons may have a chain length of up to C8 or up to C11. In particular, the separated gaseous hydrocarbons may be olefins. For example, for gasoline as the target product, the corresponding separation limit can be identified as C4, for kerosene as C8, and for diesel as C11.
[0035] By oligomerizing and subsequently supplying the resulting oligomers to the product stream of this FT reaction process, the disadvantage of increased FT temperature compared to conventional methods can be compensated for efficiently. In particular, the yield of the target product in the hydrocarbon stream on the product side of this FT reaction process can thus be increased.
[0036] According to another implementation, the method may include the following steps: - Short-chain gaseous components are separated from previously generated oligomers to produce exhaust gas streams; - The waste gas stream is supplied to a waste gas combustion unit designed to provide process heat, and / or to a waste gas utilization unit.
[0037] In particular, short-chain gaseous components with a maximum C3 or C4 chain length can be separated. In this way, on the one hand, the proportion of undesirable components when the generated oligomers are supplied to the hydrocarbon stream can be reduced. On the other hand, the undesirable components can therefore be utilized in the form of exhaust gas to improve the overall balance.
[0038] According to another implementation, the method may include the following steps: -Separation of high-boiling-point substances; and - Hydrocracking of high-boiling-point substances in a hydrocracker.
[0039] The high-boiling-point substances to be separated can be present, in particular, in the form of waxes, such as waxes with a chain length of at least C20. The separation of these high-boiling-point substances can be carried out, especially after the hydrocarbon stream has been separated into gaseous and liquid hydrocarbons, i.e., particularly involving the separated liquid hydrocarbons. Due to the increased FT temperature, the hydrocarbon stream will contain fewer high-boiling-point substances or waxes compared to conventional methods. Therefore, further energy savings can be achieved in hydrocracking compared to conventional methods. In particular, the hydrocracker can be designed to be very small, resulting in significant cost savings. Simultaneously, the yield of the target product can be increased by means of this hydrocracking.
[0040] Alternatively, since the proposed higher FT temperature results in a relatively lower wax content, the separation of high-boiling-point substances and / or hydrocracking can be omitted, further reducing investment costs and process energy compared to conventional methods. Alternatively, only hydrocracking can be omitted, and the wax can be separated and sold as a separate stream.
[0041] According to another embodiment, the method can provide a closed loop for utilizing byproducts and / or waste gases, and includes the following steps: - Output the target product, especially fuel; - Utilizing the byproducts (especially naphtha) and / or waste gas (especially by means of autothermal reforming (ATR) and / or by means of partial oxidation) to obtain recovered syngas (especially a mixture comprising CO, H2, CO2 and / or water); and - The recovered syngas is supplied to the first reaction process, so that the byproducts and / or waste gases utilized are further processed in the method by means of the closed loop, and in particular, so that the output target product is essentially the only hydrocarbon stream leaving the closed loop of the method.
[0042] The aforementioned waste gas may include all waste gas streams available in the method, particularly the waste gas stream separated from the generated oligomers.
[0043] Because this method can provide a closed loop for utilizing the byproducts and / or waste gases generated in the process, it can significantly save on the reactants CO2 and H2 produced through energy-intensive regeneration. In particular, the utilization of these byproducts can be carried out with the additional use of readily available O2 and water. In the proposed method, O2 can be provided particularly readily, for example, by using O2 from an upstream aqueous electrolyte that would otherwise be required, wherein the aqueous electrolyte always provides H2 and O2 in a 2:1 molar ratio. In this way, the overall balance of the method can be further improved.
[0044] The above objective is also achieved by a device having the features of claim 16. Advantageous improvements to the method are derived from this specification and the accompanying drawings.
[0045] Correspondingly, an apparatus is proposed, which is designed to perform the above-described method.
[0046] According to one improvement, the device may have a first reactor (particularly in the form of an RWGS reactor) designed to perform an endothermic first reaction process at a first temperature using a CO2 reactant stream and an H2 reactant stream in the form of a reverse water-gas shift reaction to produce a first intermediate product stream comprising a first CO mass stream.
[0047] In addition, the device may have a second reactor (particularly in the form of an FT reactor) designed to perform an exothermic second reaction process at a second temperature using the first CO mass stream and another H2 reactant stream in the form of a Fischer-Tropsch reaction to produce a hydrocarbon stream.
[0048] In addition, the device may have a heat transfer unit 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. Attached Figure Description
[0049] Other preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. The drawings schematically illustrate:
[0050] Figure 1 A flowchart of a method for preparing a hydrocarbon stream according to a first embodiment is shown;
[0051] Figure 2 A flowchart of the method according to the second embodiment is shown;
[0052] Figure 3 A flowchart of the method according to the third embodiment is shown;
[0053] Figure 4 , 5 6. Each of these diagrams illustrates a different embodiment of the method.
[0054] Figure 7 One embodiment of an apparatus for performing a method for preparing a hydrocarbon stream is shown; and
[0055] Figure 8 Another embodiment of an apparatus for performing a method for preparing a hydrocarbon stream is shown. Detailed Implementation
[0056] Preferred embodiments are described below with reference to the accompanying drawings. Here, in different drawings, the same, similar, or equivalent elements are given the same reference numerals, and repeated descriptions of these elements are sometimes omitted to avoid redundancy.
[0057] Figure 1 A flowchart illustrating a method for preparing a hydrocarbon stream according to a first embodiment is shown schematically. Figure 1 and Figure 7 As can be seen, the method includes the following steps: - An endothermic RWGS reaction process S10 is performed at a first temperature T1, wherein a CO2 reactant stream 10 and an H2 reactant stream 12 are present on the reactant side. By means of this RWGS reaction process, a first intermediate product stream 14 comprising a first CO mass stream 14 is generated on the product side. - An exothermic FT reaction process S20 is performed at a second temperature T2, wherein the first CO mass stream 14 and another H2 reactant stream 16 are present on the reactant side. Hydrocarbon stream 18 is generated on the product side by means of this FT reaction process. - Remove the S30 process heat 20a-d from the FT reaction process. - A first portion 20a of the process heat 20a-d is supplied to S40 in the form of a first heat flow 20a to the RWGS reaction process.
[0058] Since the process heat is transferred from the exothermic reaction process to the endothermic reaction process by means of the first heat flow 20a, the energy balance of the method can be improved.
[0059] The product-side hydrocarbon stream 18 is also referred to as "synthetic crude oil" and involves a mixture of hydrocarbons including alkanes and olefins. To obtain fuel as a primary or target product, the obtained synthetic crude oil is further processed in a series of hydrogenation processes, which are further described below.
[0060] Figure 2 A flowchart illustrating the method according to the second embodiment is shown schematically, wherein the reaction conditions of the first and second reactions are designed such that a first temperature T1 is greater than or equal to a second temperature T2. Furthermore, after the step of removing process heat 20a-d from the FT reaction process (S30), before supplying S40 to the first reaction process, an additional step is performed to heat the first heat stream 20a (S35) by means of a heat pump 22, causing the first heat stream 20a to undergo a temperature rise. The third temperature T3 of the first heat stream 20a heated by means of the heat pump 22 is at least 5 Kelvin higher than the first temperature T1.
[0061] The temperature difference between the first temperature T1 and the second temperature T2 is limited to, for example, a maximum of 100 K, or alternatively a maximum of 50 K or a maximum of 30 K, so that the heat pump 22 can operate efficiently while simultaneously transferring heat from an exothermic reaction process to an endothermic reaction process.
[0062] Figure 3A flowchart illustrating the method according to a third embodiment is shown schematically, wherein the reaction conditions of the first and second reaction processes are designed such that a second temperature T2 is greater than or equal to a first temperature T1. In this embodiment, the heat pump 22 may optionally be omitted. In one example, the second temperature T2 is at least about 5 Kelvin higher than the first temperature. In other examples, the second temperature T2 may be at least 10, 20, 30, 40, or more than 50 Kelvin higher than the first temperature T1. Optionally, the heating step S35 according to the second embodiment, using the heat pump 22, may also be performed in this third embodiment.
[0063] Figure 4 , 5 6. Flowcharts schematically illustrate other embodiments of the method. For example... Figure 4 And in addition Figure 8 As can be seen, in one embodiment, after step S10, a CO2 mass stream 24 is separated from the first intermediate product stream 14 of the first reaction process. Subsequently, the separated CO2 mass stream 24 is returned to the first reaction process in the form of another CO2 reactant stream 24.
[0064] Adding to or replacing the above embodiments, after step S30, a second portion 20b of the extracted process heat 20a-d is supplied to the first CO mass stream 14 in step S45 to execute the second reaction process in step S20. Furthermore, after step S30, a third portion 20c of the extracted process heat 20a-d is supplied to the other H2 reactant stream 16 in step S47 to execute the second reaction process in step S20. Figure 8 Therefore, in addition to step S30, a fourth portion 20d of the extracted process heat 20a-d is supplied to the subsequent step S100 in step S49 for HC separation, which becomes the main product and by-product. This step can be carried out, for example, in the fractionation column 38 to be heated. The supply of this fourth portion 20d in step S49 can be carried out in the form of a fourth heat flow 20d to heat the fractionation column 38 and / or to preheat the reactants in the fractionation column.
[0065] like Figure 5 And in addition Figure 8As can be seen, according to another embodiment, after step S20, the hydrocarbon stream 18, i.e., the product stream 18 of step S20, is separated S50 into gaseous and liquid HC components 26 and 27, and byproduct water. Step S50 can be performed by means of a central separator. After step S50, the separated gaseous hydrocarbons 26 are oligomerized S60. Optionally, after step S60, the short-chain gaseous components are separated S65 to provide exhaust gas stream 30. After step S65, the exhaust gas stream 30 is supplied to exhaust gas combustion according to step S67 to provide further process heat. Additionally or alternatively, after step S65, the exhaust gas stream 30 is supplied to the byproduct utilization unit 32 or the exhaust gas utilization unit 32 according to step S68. Furthermore, after oligomerization S60, the resulting oligomers 29 are supplied to the product stream 18 from step S20 for S70.
[0066] like Figure 6 And in addition Figure 8 As can be seen, according to another embodiment, after step S50, separation S80 of high-boiling-point substance 34 is performed. The high-boiling-point substance to be separated may be a wax 34 having a chain length of at least C20, or alternatively a wax having a chain length of at least C22, C24 or higher. Subsequently, the high-boiling-point substance 34 separated by means of hydrocracking S82 in a hydrocracker 35 is subjected to hydrocracking.
[0067] According to another embodiment, after step S50 or after step S80, isomerization and saturation of the liquid HC fraction 27 are carried out in step S90. Subsequently, in step S100, the liquid HC fraction 27 is separated into major products and byproducts, particularly naphtha 40, wax 36, and other waste gases 39. The other waste gases 39 may, for example, include compounds from methane to butane. Step S100 may be carried out, for example, by means of a fractionating column 38, which is designed to separate the target product fraction from the naphtha fraction 40 and wax 36.
[0068] In step S102, a certain proportion of the wax byproduct 36 is supplied to the hydrocracking process according to step S82. In step S104, the byproducts, particularly naphtha 40 and exhaust gas 39, are supplied to the byproduct utilization unit 32. Furthermore, in step S105, the desired main product or target product, such as fuel 41, like gasoline, kerosene, or diesel, is obtained.
[0069] The waste gas utilization unit 32 can be included in or provided separately from the by-product utilization unit 32. Waste gases 30 and 39 can be converted back to syngas in the waste gas utilization unit 32 in step S106, for example, by autothermal reforming (ATR) and / or by partial oxidation, and then supplied again as reactants in step S110, particularly in the first reaction. For example, the syngas 42 obtained from waste gas utilization can be a mixture of CO, H2, CO2, and water. By supplying syngas 42 to the first reaction in S110, the basic structural units of carbon and hydrogen are preserved to a particularly high degree in the proposed method, resulting in further improvements in overall yield. Furthermore, syngas 42 can be generated again from naphtha fraction 40 by means of reuse.
[0070] Furthermore, the utilization processes in the waste gas utilization unit 32 or by-product utilization unit 32, particularly partial or complete oxidation, may be highly exothermic. Therefore, the generated process heat, similar to process heat 20a-d, can be transferred and utilized to heat the various process stages of the proposed method.
[0071] Figure 7 and Figure 8 An embodiment of apparatus 1 for performing a method for preparing a hydrocarbon stream is schematically shown above, and has been incorporated herein by reference. Figures 1 to 6 The description provides an explanation.
[0072] The method shown can, in principle, prepare any target product in fuel form. Therefore, the equipment operator can pre-set the conditions in the process unit accordingly. For example, as the FT temperature (i.e., the second temperature T2 is chosen to be high, e.g., T2 > 500°C) increases and the H2:CO reactant ratio increases, the proportion of shorter hydrocarbon chains increases while the proportion of longer chains decreases. Therefore, the product profile shifts gradually from long-chain waxes via diesel or kerosene as middle fractions to short-chain products (e.g., naphtha, from which gasoline can be produced by hydrogenation). At very high FT temperatures, i.e., the second temperature T2 is chosen to be very high, e.g., T2 > 650°C, the product profile may even shift towards short chains with lengths less than C5. These short-chain fractions would be too light for naphtha / gasoline and would be classified as other waste gas 39 in the hydrocarbon separation according to step S100.
[0073] Wherever available, all the various features shown in the embodiments can be combined and / or interchanged with each other without departing from the scope of the invention. For example, heat pump 22 and the corresponding step S35 can be used in each embodiment. Furthermore, high-boiling-point substance separation and hydrocracking S82 according to step S80 are optional, such that isomerization and saturation S90 can be performed immediately after step S20 or S50.
Claims
1. A method for preparing a hydrocarbon stream, the method comprising the following steps: - In the form of reverse water gas shift (RWGS) reaction, an endothermic first reaction process (S10) is performed at a first temperature (T1) using CO2 reaction stream (10) and H2 reaction stream (12) to produce a first intermediate product stream (14) including a first CO mass stream (14). - In the form of a Fischer-Tropsch (FT) reaction, at a second temperature (T2), the first CO mass stream (14) and another H2 reactant stream (16) are used to perform an exothermic second reaction process (S20) to produce a hydrocarbon stream (18). - Remove the process heat (20a-d) from the second reaction process (S30); and - A first portion (20a) of the process heat (20a-d) is supplied (S40) 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), particularly before being supplied (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 (T1). Specifically, the third temperature (T3) is at least higher than the first temperature (T1) by a difference (d), wherein the difference (d) is in the range of 5 K to 100 K, particularly in the range of 5 K to 50 K, and further in the range of 10 K to 30 K.
3. The method according to claim 1 or 2, wherein, The method includes the following steps: If the first temperature is greater than or equal to the second temperature. Before supplying (S40) to the first reaction process (RWGS), the first heat flow (20a) is heated (S35) by means of a heat pump (22), in particular, so that the first heat flow (20a) has the third temperature (T3).
4. The method according to any one of claims 1 to 3, wherein, The first temperature is between 300°C and 700°C, particularly between 400°C and 650°C, and further between 450°C and 600°C, and wherein the second temperature is between 300°C and 600°C, particularly between 400°C and 550°C, and further 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 (T1).
6. The method according to claim 5, wherein, The second temperature (T2) is at least 5 K higher than the first temperature (T1), particularly at least 10 K, and further at least 20 K.
7. The method according to any one of claims 5 or 6, wherein, The first temperature (T1) is less than 800°C, particularly less than 600°C, and further less than 500°C.
8. The method according to any one of claims 5 to 7, wherein, The steps of removing (S30) process heat (20a-d) from the first reaction process (RWGS) and / or supplying (S40) a first portion (20a) of the process heat (20a-d) to the first reaction process (RWGS) in the form of the first heat flow (20a) are carried out using a heat exchanger and / or a heat transfer fluid, particularly steam and / or a salt melt.
9. The method according to any one of the preceding claims, the method comprising the following steps: - A second portion (20b) of the process heat (20a-d) taken out (S30) is supplied (S45) to the first CO mass stream (14) to perform (S20) the second reaction process (FT).
10. The method according to any one of the preceding claims, the method comprising the following steps: - A third portion (20c) of the process heat (20a-d) taken out (S30) is supplied (S47) to the other H2 reaction stream (16) to perform (S20) the second reaction process (FT).
11. The method according to any one of the preceding claims, the method comprising the following steps: - Separate (S12) CO2 mass stream (24) from the first intermediate product stream (14) of the first reaction process (RWGS). and - The separated CO2 mass stream (24) is returned (S14) to the first reaction process (RWGS) as another CO2 reactant stream (24).
12. The method according to any one of the preceding claims, the method comprising the following steps: - The hydrocarbon stream (18) is separated (S50) into gaseous hydrocarbons (26) and liquid hydrocarbons (27), the gaseous hydrocarbons being in particular olefins, wherein the separated gaseous hydrocarbons (26) have a chain length of at most C4, at most C8 or at most C11; - To oligomerize the separated gaseous hydrocarbon (26) (S60); - The resulting oligomer (28) is supplied (S70) to the hydrocarbon stream (18).
13. The method according to any one of the preceding claims, comprising the following steps: - Separate (S65) short-chain gaseous components, particularly gaseous components with a maximum C3 or C4 chain length, from the resulting oligomers (28) to generate an exhaust gas stream (30). - The waste gas flow (30) is supplied (S67) to the waste gas combustion unit, which is designed to provide process heat, and / or the waste gas flow (30) is supplied (S68) to the waste gas utilization unit (32).
14. The method according to any one of the preceding claims, the method comprising the following steps: - Separate (S80) high-boiling-point substances (34), especially high-boiling-point substances in the form of waxes with a chain length of at least C20; and - The high-boiling-point product (34) is hydrocracking (S82) in a hydrocracker (35).
15. The method according to any one of the preceding claims, wherein, The method provides a closed loop for utilizing byproducts (40) and / or waste gases (30, 39), and includes the following steps: Remove (S105) the target product, particularly the fuel (41). In particular, by means of autothermal reforming (ATR) and / or by means of partial oxidation, using the byproducts (40) described in (S106), particularly naphtha (40) and / or waste gas (30, 39), to obtain recovered syngas (42), particularly syngas having a mixture comprising CO, H2, CO2 and / or water; and The recovered syngas (42) is supplied (S110) to the first reaction process (RWGS) such that the byproducts (40) and / or waste gases (30, 39) utilized (S106) are further processed in the method by means of the closed loop, and in particular, the target product (41) taken out (S105) is substantially the only hydrocarbon stream leaving the closed loop of the method.
16. An apparatus (1) designed to perform the method according to any one of the preceding claims.