Yield-optimised gasifier-based fischer-tropsch process, and plant for producing renewable kerosene

Abstract

The present invention relates to a process for synthesising renewable kerosene (22), the process comprising: carrying out (S10) gasification of carbonaceous reactants in order to produce a synthesis gas stream (12); carrying out (S20) a Fischer-Tropsch reaction using the synthesis gas stream (12) in order to produce a hydrocarbon stream (14); cooling and separating (S30) the hydrocarbon stream (14) by means of a separator (30) in order to produce a synthetic crude stream (16), wherein the synthetic crude stream (16) contains in particular medium-length and long-chain hydrocarbons; hydrocracking (S40) the synthetic crude stream (16) by means of a hydrocracker (40) in order to produce a paraffin stream (18); fractionating (S50) the paraffin stream (18) in order to produce a kerosene stream (22) and to discharge the kerosene stream as a target product stream (22), and in order to produce a byproduct stream (24); returning (S70) the byproduct stream (24) to the gasification. The invention also relates to a plant (1).

Description

[0001] Description

[0002] Yield-optimized carburetor-based Fischer-Tropsch process and plant for the production of renewable kerosene

[0003] The present invention relates to a method and a plant for the synthesis of regenerative kerosene.

[0004] For the production of renewable hydrocarbon products, especially regeneratively produced kerosene, it is known to generate renewable oxygen and hydrogen via electrolysis. Using the renewable oxygen, carbon-containing feedstocks, such as biomass or waste, are gasified in a gasification unit to produce synthesis gas.

[0005] In the so-called Fischer-Tropsch route (hereinafter abbreviated as "FT"), the synthesis gas is then converted together with the renewable hydrogen to form a hydrocarbon stream, which is further treated and fractionated to obtain fuels such as diesel or kerosene.

[0006] The FT route has the advantage of ASTM certification, which permits the blending of up to 50% by weight of so-called FT kerosene into commercial aviation fuel. A disadvantage of the FT route is that, in addition to the target product kerosene, it also yields a very wide range of byproducts, some of which are complex to process further, in the form of hydrocarbons (hereinafter abbreviated as "HCs"), such as HC exhaust gases, C3 / C4 HC mixtures, naphtha, and waxes.

[0007] In the prior art, plants for the synthesis of so-called renewable kerosene are known, comprising a gasification unit for generating synthesis gas, a downstream FT reactor for generating hydrocarbon electricity, a downstream cooler and separator for cooling and separating the generated hydrocarbon electricity and for generating a syncrude stream, and a downstream hydrocracker for cracking and isomerizing the hydrocarbons and hydrogenating olefins, ultimately providing a stream of isomerized paraffins. The latter is typically fractionated in a fractionation column to enable the extraction of fuels as target products.

[0008] Current technology requires a high degree of fractionation effort, while the byproducts of fuel production also undergo complex further processing. In some cases, byproducts or process exhaust gases are also thermally utilized to provide process heat for the plant itself or for other facilities. In this way, conventional plants regularly achieve a yield of less than 40% of the target product, kerosene. In other words, the majority of the carbon-containing feedstocks used ultimately do not result in the target product, kerosene.

[0009] Summary of the invention

[0010] Starting from the known state of the art, it is an object of the present invention to provide a more efficient process and a more efficient plant for the synthesis of regenerative kerosene, for example with an improved yield of kerosene based on the carbon-containing starting materials used.

[0011] The problem is solved by a method with the features of claim 1. Advantageous further developments are described in the dependent claims, the description, and the figures.

[0012] Accordingly, a procedure is proposed comprising the following steps:

[0013] Performing gasification of carbon-containing reactants to generate a synthesis gas stream; performing a Fischer-Tropsch reaction using the synthesis gas stream to generate a hydrocarbon stream;

[0014] - Cooling and separating the hydrocarbon stream using a separator to generate a syncrude stream, wherein the syncrude stream contains in particular medium-chain and long-chain hydrocarbons;

[0015] - Hydrocracking of the syncrude stream using a hydrocracker to generate a paraffin stream; fractionation of the paraffin stream to generate a kerosene stream and to discharge this as the target product stream, and to generate a by-product stream;

[0016] Returning the by-product stream to the gasification process.

[0017] For the purposes of this document, "carbon-containing feedstocks" are understood to mean, in particular, substances from biomass or waste intended for regenerative or sustainable utilization. Furthermore, carbon-containing feedstocks typically include readily available substances from a process engineering perspective, such as exhaust gases or flue gases, which are easily accessible for utilization in a gasification unit.

[0018] Furthermore, the term "hydrocarbon stream" is understood here to mean a material stream containing hydrocarbon compounds, but which may also contain, in particular, hydrogen, water, carbon monoxide, and / or carbon dioxide. Cooling of the hydrocarbon stream can be achieved by means of a cooling unit installed upstream of the separator.

[0019] Syncrude streams can contain, in particular, medium- and long-chain hydrocarbons. In this context, syncrude refers to a synthetic crude oil that can be produced by FT synthesis and further refined. Thus, syncrude comprises a hydrocarbon mixture containing, in particular, paraffins and olefins.

[0020] In the course of the present invention, it was recognized that the yield of the target product kerosene can be drastically increased with respect to the use of carbon-containing feedstocks by foregoing purely thermal utilization of exhaust gases for the purpose of generating process heat. Thus, byproducts can be utilized materially instead of being purely thermally utilized.

[0021] Furthermore, it was recognized that some or even all byproducts can be recycled back into the process or a corresponding plant, instead of undergoing complex processing in further processes or plants. In this way, a cycle can be created for the exhaust gases and byproducts generated during the process or within the plant, so that, in the case of complete recycling of the byproducts, the carbon reactants used can be essentially completely converted into the target product to be discharged.

[0022] In the context of this disclosure, "essentially" means that process inaccuracies, fluctuations, or leaks are negligible. Thus, in a steady-state, fully closed-loop operation of the process or plant, a carbon feedstock remains in the process cycle until it is converted to the target product and subsequently discharged.

[0023] To this end, the present disclosure proposes generating a byproduct stream during the fractionation of the paraffin stream, which is then recycled and gasified. This byproduct stream is thus recirculated and fed back to the carbon reactants. In this way, the reactants present as byproducts after fractionation are not lost to the process but can be converted into the target product, kerosene, via the cycle. In other words, thanks to the recycling and gasification, the disclosed process converts hydrocarbon byproducts into synthesis gas, which can then be reacted with the downstream reactions to produce the target product, kerosene. This significantly improves the kerosene yield.

[0024] The synthesis gas or synthesis gas stream contains in particular a mixture comprising CO, CO2, H2 and H2O.

[0025] Furthermore, the process can include the following step: CO2 removal from the synthesis gas stream. This removal can be carried out, in particular, using a reverse water-gas shift reactor (hereinafter "RWGS") and / or a carbon capture unit. Additionally, prior to CO2 removal, the synthesis gas stream can be purified to remove or reduce impurities and / or catalyst poisons.

[0026] By removing CO2, which acts inertly in an FT reaction, a corresponding FT reactor can be designed and operated more efficiently.

[0027] Furthermore, the byproduct stream can be either gaseous or liquid. For example, only the exhaust gases can be recycled as the sole gaseous byproduct stream, while the liquid byproducts are used elsewhere.

[0028] Furthermore, the liquid by-products can be evaporated after fractionation and returned to the corresponding gasification unit separately from the exhaust gas or together with it as a by-product stream.

[0029] Alternatively, the byproduct stream can comprise a gaseous and a liquid substream. The gaseous and liquid substreams can be recycled separately. Separating the byproducts and managing them as substreams enables various operating modes for the process or plant.

[0030] Furthermore, all byproducts generated during fractionation can be recycled in a common byproduct stream, particularly via a shared recirculation line. In this case, the byproducts can include, in particular, exhaust gas, a C3 / C4 mixture, and naphtha, and recycling can be carried out in the gaseous state. For example, the corresponding byproduct stream can simply be drawn off at the top of the fractionation column, especially without condensation. In this way, the fractionation effort can be significantly reduced, since in the range of Cl to C18 hydrocarbons, only a single separation between the byproduct stream and the target product, kerosene, is required.

[0031] Furthermore, the procedure may include:

[0032] - Separation of a separator exhaust gas stream containing, in particular, CO, H2, CO2 and short-chain hydrocarbons;

[0033] - Utilizing the substances from the separator exhaust gas stream by means of gasification.

[0034] The utilization of the materials from the separator exhaust gas stream includes both direct, or stepless, utilization via gasification, and a case in which the separator exhaust gas stream undergoes a further intermediate reaction, as explained below with reference to an intermediate pre-reformer. Thanks to the utilization of the exhaust gas stream, the proportion of carbon reactants in the cycle can be further increased.

[0035] Furthermore, the step of fractionating the paraffin stream can include: generating and diverting a diesel stream as a further target product stream.

[0036] Additionally or alternatively, the paraffin stream fractionation step can include generating a further byproduct stream and feeding this stream into the hydrocracker. This further byproduct stream can, in particular, include diesel. For example, an initial portion of diesel can be discharged as the target product stream, and a second portion can be returned to the cycle. In this way, a desired target quantity of diesel can be produced very easily, with the excess diesel being utilized within the cycle. Thus, the quantity of diesel discharged as the target product can be easily controlled, especially by regulating valves or flow rates, so that additional changes to other reactor process parameters are not required.For example, it is therefore not necessary to adjust the pressure and / or temperature of reactions in order to influence the equilibrium reactions to control the diesel yield.

[0037] Furthermore, the additional byproduct stream may contain, in particular, long-chain paraffins, such as waxes. In addition, the additional byproduct stream may include separated substreams of the long-chain paraffins and the diesel in separate lines.

[0038] Furthermore, the by-product stream can consist essentially of hydrocarbons with a chain length in the range of CI to C7.

[0039] Additionally or alternatively, the further byproduct stream may contain long-chain paraffins, particularly in the form of waxes. Furthermore, the further byproduct stream may contain diesel.

[0040] Furthermore, the process can include reforming the by-product stream using a pre-reformer to increase the methane content. Thanks to the increased methane content in the by-product stream, gasification or the operation of a gasification unit can be simplified.

[0041] In this context, a "pre-reformer" is understood to be a reactor unit, also referred to as a pre-reformer in the prior art, and is typically always used in conjunction with a main reactor unit for steam reforming or autothermal reforming (ATR). Accordingly, in the pre-reformer, heavier hydrocarbons, such as naphtha, or lighter hydrocarbons are converted into lighter components such as methane, hydrogen, carbon monoxide, and carbon dioxide.

[0042] Furthermore, the process can include the following step: inerting a system configured to carry out the process in order to purge air that has entered the system using a purge gas, wherein the purge gas is CO2, water vapor, or a sequential combination of nitrogen and methane. The air to be purged may have entered the system, in particular, during commissioning or recommissioning.

[0043] In this context, a sequential combination of nitrogen and methane is understood to mean that the system can first be purged with nitrogen, and then the nitrogen can be displaced by methane. In this case, the resulting nitrogen-methane exhaust gas can be flared off.

[0044] Thanks to the inerting process described above, extraneous inert gases can be replaced by process-related gases. In particular, it can be ensured that any temporarily introduced inert gases, such as nitrogen, are displaced from the system before the commencement of continuous operation or the operation of the corresponding plant. This prevents the accumulation of extraneous inert gases over time, which would hinder the complete utilization of the exhaust gas streams as described above. In other words, the risk of inert gas accumulation in the gas circuit described above can be largely eliminated.

[0045] Furthermore, the procedure may include the following steps:

[0046] - Generating electrolysis hydrogen as an additional reactant using an electrolysis unit; - Separating a water condensate using the separator;

[0047] - Treatment of the water condensate, in particular by means of biological treatment using reverse osmosis; and

[0048] Feeding the water condensate as deionized water to the electrolysis unit.

[0049] In this way, the ion-free water that accumulates as wastewater in the separator can be reused in a closed loop for the process or the corresponding system. This reduces the amount of water that needs to be deionized specifically for operating the electrolysis unit. As a result, the process or system can be operated even more sustainably.

[0050] The problem stated above is further solved by a system with the features of claim 11. Advantageous embodiments of the system are described in the dependent claims, the description, and the figures. Accordingly, a system for the synthesis of renewable kerosene is proposed, comprising a gasification unit, a Fischer-Tropsch reactor, a separator, a hydrocracker, and a fractionation column. The system also includes a feed line by means of which an outlet of the fractionation column is connected to a reactant of the gasification unit.

[0051] In particular, a cooling unit can be installed upstream of the separator to cool the hydrocarbon stream.

[0052] The definitions, technical effects, and advantages explained above for the disclosed process apply equally to the proposed plant. In particular, the chemical and structural components and technical units described in the context of the process correspond to the chemical and structural components and technical units of the same name described in the context of the proposed plant. Furthermore, the plant may include at least one target product discharge and a substantially closed-loop system for carbon-containing byproducts. For example, the plant may include a first target product discharge for kerosene and a second target product discharge for diesel.Thanks to the essentially closed-loop system for carbon-containing byproducts, the lighter byproducts in the range of hydrocarbon chain lengths C1-C7 can be recycled back to the gasification unit, while the heavier byproducts in the range >C20 can be fed back to the hydrocracker after the fractionation column. In this way, the target product yield can be significantly increased.

[0053] Furthermore, the plant can include a reverse water-gas shift reactor and / or a carbon capture unit to remove CO2 from the synthesis gas stream.

[0054] Furthermore, the plant can include a pre-reformer, which is downstream of the fractionation column and connected to the gasification unit via the feed line in order to increase the methane content of the by-product stream.

[0055] Furthermore, the system can include an electrolysis unit, with the separator being connected to the electrolysis unit to supply the electrolysis unit with deionized water.

[0056] Brief description of the characters

[0057] Exemplary embodiments of the invention are explained in more detail by the following description of the figures. These show schematically:

[0058] Figure 1 shows a flow diagram of a process for the synthesis of regenerative kerosene according to a first implementation form;

[0059] Figure 2 shows a flow diagram of the process according to further embodiments; Figure 3 shows an embodiment of a plant for the synthesis of renewable kerosene according to one embodiment; and

[0060] Figure 4 shows another embodiment of the system from Figure 3.

[0061] Detailed description of implementation examples

[0062] The following section describes individual embodiments with reference to the figures. Identical, similar, or equivalent elements in the different figures are marked with identical reference symbols, and repeated descriptions of these elements are sometimes omitted to avoid redundancy.

[0063] For better understanding, the process steps described in connection with Figures 1 and 2 are additionally shown with corresponding reference symbols in Figures 3 and 4.

[0064] Figure 1 schematically shows a flow diagram of a process for the synthesis of renewable kerosene according to a first embodiment. As can be seen from Figures 1 and 3, the process comprises the following steps:

[0065] Performing S10 a gasification of carbon reactants to generate a synthesis gas stream 12;

[0066] Performing S20 a Fischer-Tropsch reaction using the synthesis gas stream 12 to generate a hydrocarbon stream 14;

[0067] - Cooling and separating S30 of the hydrocarbon stream 14 by means of a separator 30 to generate a syncrude stream 16, wherein the syncrude stream 16 contains in particular medium-chain and long-chain hydrocarbons;

[0068] - Hydrocracking S40 of the syncrude stream 16 using a hydrocracker 40 to generate a paraffin stream 18; fractionating S50 of the paraffin stream 18 to generate a kerosene stream 22 and to discharge this as target product stream 22, and to generate a by-product stream 24;

[0069] Returning S70 of the by-product stream 24 to the gasification process.

[0070] Figure 3 shows an embodiment of a plant 1 for the synthesis of renewable kerosene. The plant 1 comprises a gasification unit 10 for carrying out step S10; a Fischer-Tropsch reactor 20 for carrying out step S20; a cooling unit (not shown) and the separator 30 for carrying out step S30; the hydrocracker 40 for carrying out step S40; and a fractionation column.

[0071] 50 for carrying out step S50. The system 1 also includes a feed line 70, by means of which an output side

[0072] 51 of the fractionation column 50 is connected to a reactant side 10a of the gasification unit 10.

[0073] To avoid repetition, reference is made to the preceding description regarding technical effects as well as the definitions and abbreviations used. The process and Annex 1 are explained in more detail below, first with reference to Figures 1 to 3.

[0074] In gasification unit 10, in step S10, the carbon reactants, in particular CHO compounds, are converted to synthesis gas using electrolysis oxygen and steam. Depending on the composition of the carbon reactants, especially their ratios of C, H, and O compounds, as well as depending on the oxygen and steam used as gasification agents, the ratio of the gasification products in the synthesis gas stream 12 can be influenced according to the following qualitative reaction equation: CHO substances + H₂O + O₂ → CO₂ / CO₂ / H₂ / H₂O mixture (1)

[0075] The gasification unit 10 also includes a gas purification unit for cleaning the synthesis gas stream 12, in particular for removing or reducing impurities and / or catalyst poisons. In step S15, CO2 can be removed from the synthesis gas stream 12. This removal can be carried out using a carbon capture unit 15b, whereby the removed CO2 can be fed back to the gasification unit 10, where it can be used as a barrier gas. In one variant, the carbon capture unit-depleted synthesis gas stream 12 can then be fed directly to the FT reactor 20.

[0076] Alternatively, a reverse water-gas shift reactor 15a can be connected downstream of the carbon capture unit 15b for further CO2 reduction, with the synthesis gas stream 12 then being fed to the FT reactor 20. The reverse water-gas shift reactor 15a can be supplied with renewable hydrogen from an electrolysis unit 38, which generates electrolysis hydrogen as an additional reactant according to step S8.

[0077] The RWGS reaction according to step S15 is endothermic and can be carried out at an RWGS temperature in the range of 800 to 1000 °C. In this way, the RWGS equilibrium can be shifted towards the desired RWGS product CO, according to the following equation: CO₂ + H₂ → CO₂ + H₂O (2)

[0078] Furthermore, both the carbon capture unit 15b and the RWGS reactor 15a can be connected between the gasification unit 10 and the FT reactor 20, as shown in Figure 3. In this case, the carbon capture unit 15b primarily serves to extract smaller quantities of CO2 from the synthesis gas stream in order to supply it to the gasification unit 10 as a barrier gas. Thus, a large proportion of the CO2 remains in the synthesis gas stream 12 downstream of the carbon capture unit 15b, and the RWGS reactor 15a is responsible for the majority of the CO2 removal.

[0079] On the reactant side, H₂ in molar excess and CO₂, for example in a ratio of approximately 3:1, are fed into the RWGS reactor 15a. On the product side, the unreacted CO₂ and the excess H₂ remain after the RWGS reactor 10, so that the synthesis gas stream 12 processed by the RWGS reactor 15a comprises a gas mixture containing CO₂, H₂, CO, and H₂O. Condensed water can optionally be removed.

[0080] The synthesis gas stream 12 is then fed to the FT reactor 20 for step S20, in which a hydrocarbon stream 14 is generated at an FT temperature in the range of 250 to 300 °C on the heterogeneous catalyst. The heterogeneous catalyst can be, in particular, a cobalt- or iron-based catalyst. The hydrocarbon stream 14 is a mixture of hydrocarbons, especially olefins and paraffins, with a typically very broad distribution of hydrocarbon chains for the FT reaction. In addition to the paraffin-olefin mixture, the hydrocarbon stream 14 also contains residues of the unreacted gases CO2, H2, and CO, as well as unreacted water of reaction.

[0081] The following equations (3) and (4) describe the product formation in the FT reactor 20, respectively according to step S20:

[0082] Olefin formation: n CO + 2n H2 (CH2) n + n H2O (3)

[0083] Paraffin formation: n CO + (2n+l) H2 H- (CH2)nH + nH2O (4)

[0084] In step S30, the hydrocarbon stream 14 is cooled by means of a cooling unit (not shown) and separated by means of the separator 30. This means that water, as well as medium- and long-chain hydrocarbons, are condensed from the gaseous hydrocarbon stream 14 by cooling. In contrast, the gaseous hydrocarbons of the unreacted reactants remain gaseous. The mixture of the condensed substances decomposes into two phases, which are separated in the separator 30.

[0085] Due to its higher density, a water condensate 42 can be drawn off from the bottom of the separator 30. Since the water condensate 42 is deionized, it can be treated in step S35 and fed to the electrolysis unit 38 in step S36, so that electrolysis hydrogen is produced in step S8 for step S10, which uses deionized water from the cycle of the disclosed process or plant 1 (see Figures 2 and 3). The treatment can be carried out using a treatment plant 37, for example, a biological treatment in conjunction with reverse osmosis.

[0086] With reference to step S30 again, the mixture of medium- and long-chain hydrocarbons in the form of the syncrude stream 16 is obtained as a further liquid phase in the separator 30.

[0087] The syncrude stream 16 is now fed to the hydrocracker 40 together with gaseous hydrogen. During hydrocracking S40, long-chain hydrocarbons, especially those with a chain length >C20, such as waxes, are split into shorter and medium-length hydrocarbons.

[0088] Furthermore, in the hydrocracker 40, the unbranched hydrocarbon chains produced in the FT reactor 20 are isomerized by introducing side chains. Additionally, the olefins are hydrogenated. Consequently, a mixture of isomerized paraffins with shorter and medium-length chains is produced, which is fed as paraffin stream 18 to the fractionation column 50. The paraffin stream 18 also contains waxes, i.e., long-chain hydrocarbons, since their conversion during cracking in the hydrocracker 40 is not complete.

[0089] In step S50, the paraffin stream 18 is separated into fractions by distillation. According to the disclosure, at least the kerosene stream 22 and the by-product stream 24 are produced as fractions. The by-product stream 24 can consist essentially of hydrocarbons with a chain length in the range of C1 to C7. In the present context, "essentially" means that hydrocarbons with a chain length of C8 or more may also be present, either occasionally or to a negligible extent.

[0090] In addition, a further by-product stream 34 comprising long-chain paraffins, in particular waxes, can be produced (step S54), which can be fed to the syncrude stream 16 or the hydrocracker 40 (step S56), so that the further by-product stream 34 is again subjected to a hydrocracker S40 and thus remains in the cycle of the process or plant 1.

[0091] In step S70, the by-product stream 24 is fed to the gasification unit 10 via a feed line 70. As shown in Figure 3, the feed line 70 can comprise several individual lines 70 for returning the by-product stream 24 or its individual partial streams 24a, 24b, 24c. For example, a first partial stream 24a can contain hydrocarbon exhaust gas, a second partial stream 24b can contain C3-C4 hydrocarbons, and a third partial stream 24c can contain naphtha. In this case, the fractionation products are fed separately to a pre-reformer 60. Alternatively, the fractionation products can be fed to the pre-reformer 60 in a common feed line 70.

[0092] Furthermore, as described above, the outlet 51 of the fractionation column 50 is connected to the feed side 10a of the gasification unit 10 by means of the feed line 70. The feed line 70 can be interrupted by the pre-reformer 60, as shown in Figure 3, or it can extend continuously from the fractionation column 50 to the gasification unit 10. In other words, the feed line 70 can connect the outlet 51 of the fractionation column 50 directly to the feed side 10a of the gasification unit 10 (not shown in Figure 3). Thus, the feed line 70 essentially has the function of conveying the by-product stream 24, or its individual partial streams 24a, 24b and 24c, from the fractionation column 50 to the gasification unit 10, regardless of whether the pre-reformer 60 is interposed or not.

[0093] In the optionally interposed pre-reformer 60, the by-product stream 24 is reacted with steam at temperatures between 250 and 500 °C on the heterogeneous catalyst according to the following equation (5) in order to increase the methane content of the by-product stream (24) (step S 60 ):

[0094] Pre-referring: C n H m + x H2O CH4 / CO / CO2 / H2 / H2O (5)

[0095] Nickel-based catalysts can be used in the Pre-Reformer 60. The steam-carbon ratio is 2:1 to 3:1, for example, 2.5:1 to 3:1. The reaction pressures range from 1 to 40 bar, particularly between 10 and 30 bar, for example, between 15 and 25 bar.

[0096] The reforming of S60 in the pre-reformer 60 according to the reaction equation (4) above proceeds endothermically or exothermically, depending on the product ratio. More precisely, the reaction is weakly endothermic if more CO than CO2 is formed alongside CH4; conversely, it is slightly exothermic if more CO2 than CO is formed alongside CH4. The pre-reformer 60 can be operated adiabatically. Thus, in the case of an exothermic reaction, the reacting gas mixture heats up, and in the case of an endothermic reaction, it cools down.

[0097] In separator 30, a separator exhaust gas stream 28 can be separated (step S32). This separator exhaust gas stream 28 contains, in particular, CO, H2, CO2, and short-chain hydrocarbons. It is optionally fed to the pre-reformer 60 and reformed to increase the methane content of the separator exhaust gas stream 28. Subsequently, it is fed via the feed line 70 to the gasification unit 10, so that the substances in the separator exhaust gas stream 28 are ultimately utilized by gasification (step S72), as shown in Fig. 3. In this way, the yield of the target product can be further increased.

[0098] Alternatively, the separator exhaust gas stream 28 can be fed directly to the gasification unit 10 without using the pre-reformer 60, so that the substances in the separator exhaust gas stream 28 are directly utilized by gasification (step S72). In this way, the yield of the target product can be further increased.

[0099] Figure 2 schematically shows a flow diagram of the method according to further embodiments. In particular, Figure 2 illustrates individual further developments that can be applied alone or in combination to the method according to the disclosure or to Annex 1.

[0100] The exemplary further development of the recycling of the deionized water condensate 42 from the separator 30 according to steps S33, S35, S36, S8 and S10 has already been described with reference to Figure 3. The same applies to the exemplary further development of the recycling of the further by-product stream 34 according to steps S50, S54, S56 and S40, which has also been described with reference to Figure 3. The same applies to the exemplary further development of the recycling of the separator exhaust gas stream 28 according to steps S30, S32, and S72, which has also been described with reference to Figure 3.

[0101] According to a further exemplary development, as a sub-step of step 50 fractionation in step S52, a diesel stream 32 is generated and discharged from the process or plant 1 in the form of a further target product stream 32 (see Figure 2). Alternatively, the diesel stream 32 can be generated in the fractionation column 50 and fed completely or partially, in particular by means of a controllable branch, to the further by-product stream 34.

[0102] In this way, a desired quantity of diesel can be produced as a further target product, with any excess diesel being utilized within the cycle. Thus, the amount of diesel discharged can be regulated without requiring any further changes to the process parameters of the reactors in Plant 1.

[0103] Figure 4 shows another embodiment of the plant 1 from Figure 3. In this example, the kerosene stream 22 is discharged as the sole target product. Diesel resulting from the fractionation is returned to the hydrocracking unit S40 together with the other by-product stream according to step S54.

[0104] Furthermore, according to the example shown in Figure 4, plant 1 does not include either the pre-reformer 60 or the RWGS reactor 15a. Accordingly, the separator exhaust gas stream 28 is directly returned to the reactant side 10a gasification unit 10. Furthermore, the electrolysis hydrogen is directed from the electrolysis unit to the FT reactor 20.

[0105] Furthermore, the return of the by-product stream 24 to the gasification takes place in a single, common feed line 70 which directly connects the outlet side 51 of the fractionation column 50 with the reactant side 10a of the gasification unit 10.

[0106] The embodiment shown in Figure 4 is characterized by a very low equipment requirement, while at the same time the cycle approach described above for the process or plant 1 can be implemented to a very high degree. Where applicable, all individual features shown in the embodiments can be combined and / or exchanged without departing from the scope of the invention. For example, individual optional developments according to the embodiment of Figure 3 can be applied in the embodiment according to Figure 4. This applies in particular to the further target product stream 32 for diesel, the interposition of the pre-reformer 60, and the provision of the RWGS reactor 10.

Claims

Patent claims 1. Method for the synthesis of regenerative kerosene (22) , comprising the following steps: Carrying out (S10) a gasification of carbonaceous reactants to generate a synthesis gas stream (12); carrying out (S20) a Fischer-Tropsch reaction using the synthesis gas stream (12) to generate a hydrocarbon stream (14); - Cooling and separating (S30) the hydrocarbon stream (14) by means of a separator (30) to generate a syncrude stream (16), wherein the syncrude stream (16) contains in particular medium-chain and long-chain hydrocarbons; - Hydrocracking (S40) of the syncrude stream (16) by means of a hydrocracker (40) to generate a paraffin stream (18); Fractionation (S50) of the paraffin stream (18) to generate a kerosene stream (22) and to discharge this as the target product stream (22), and to generate a by-product stream (24); characterized by returning (S70) the by-product stream (24) to the gasification.

2. The method of claim 1, comprising the following step: - Removing (S15) CCf from the synthesis gas stream (12) , in particular by means of a reverse water-gas shift reactor (15a) and / or by means of a carbon capture unit (15b) .

3. The method of claim 1 or 2, wherein the by-product stream (24) is either gaseous or liquid.

4. Method according to claim 1 or 2, wherein the by-product stream comprises a gaseous partial stream and a liquid partial stream, in particular wherein the recirculation (S70) of the gaseous and liquid partial streams is carried out separately.

5. A method according to any of the foregoing claims, further comprising: - Separation (S32) of a separator exhaust gas stream (28) which contains in particular CO, H2, CO2 and short chain hydrocarbons; - Utilization (S72) of the substances from the separator exhaust stream (28) by means of gasification.

6. Method according to any one of the preceding claims, wherein the step comprises fractionating (S50) the paraffin stream (18): - Generating and venting (S52) a diesel stream (32) as a further target product stream (32); and / or - Generating (S54) another by-product stream (34) and feeding (S56) the further by-product stream (34) to the hydrocracker (40) .

7. A method according to any of the preceding claims, wherein the by-product stream (24) consists essentially of hydrocarbons with a chain length in the range of CI to C7, and / or wherein the further by-product stream (34) contains long-chain paraffins, in particular in the form of waxes, and optionally diesel.

8. A method according to any of the foregoing claims, further comprising: - Reforming (S60) the by-product stream (24) using a pre-reformer (60) to increase the methane content of the by-product stream (24).

9. A method according to any of the foregoing claims, further comprising: Inerting (S5) a plant (1) which is set up to carry out the process in order to flush out air which has entered the plant (1) by means of a purge gas, in particular during commissioning or recommissioning of the plant (1), wherein the purge gas is CO2, water vapor or a sequential combination of nitrogen and methane.

10. A method according to any of the foregoing claims, further comprising: - Production (S8) of electrolysis hydrogen as an additional reactant using an electrolysis unit (38) ; - Separation (S33) of a water condensate (42) using the separator (30) ; - Treatment (S35) of the water condensate (42), in particular by means of biological treatment using reverse osmosis; and Feeding (S36) the water condensate (42) as deionized water to the electrolysis unit (38) .

11. Plant (1) for the synthesis of regenerative kerosene (22) , comprising a gasification unit (10) , a Fischer-Tropsch reactor (20) , a separator (30) , a hydrocracker (40) and a fractionation column (50) , characterized by a feed line (70) , by means of which an outlet side (51) of the fractionation column (50) is connected to a reactant side (10a) of the gasification unit (10).

12. Plant (1) according to claim 11, comprising at least one target product discharge (22, 32) and a substantially closed cycle for carbon-containing by-products.

13. Plant (1) according to claim 11 or 12, comprising a reverse water-gas shift reactor (15a) and / or a carbon capture unit (15b) to remove CO2 from the synthesis gas stream (12).

14. Plant (1) according to one of claims 11 to 13, comprising a pre-reformer (60) which is downstream of the fractionation column (50) and connected to the gasification unit (10) by means of the feed line (70) in order to increase a methane fraction of the by-product stream (24).

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