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

Abstract

The present invention relates to a process for the synthesis of renewable kerosene (22), comprising: carrying out (S10) a gasification of carbon-containing 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) 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); return (S70) of the by-product stream (24) to the gasification. The invention further relates to a plant (1).

Description

The present invention relates to a process and a plant for the synthesis of regenerative kerosine.For the production of regenerative hydrocarbon products, in particular regeneratively produced kerosine, it is known to produce regenerative oxygen and hydrogen by means of electrolysis. Using the regenerative oxygen, carbonaceous educts, for example biomass or waste, are gasified in a gasification unit to produce a synthesis gas.In the so-called Fischer-Tropsch route (hereinafter "FT"), the synthesis gas is then reacted together with the regenerative hydrogen to form a hydrocarbon stream which is post-treated and fractionated to obtain fuels such as diesel or kerosine.The FT route has the advantage that an ASTM certification is present for this purpose, which allows the addition of up to 50 percent by weight of so-called FT kerosine in commercial aircraft fuel. It can be regarded as disadvantageous in the FT route that the FT route, in addition to the target product kerosine, also provides a very broad distribution of by-products, some of which are complicated to further use, in the form of hydrocarbons (abbreviated hereinafter as "HC"), for example HC offgases, C3 / C4-HC mixtures, naphtha and waxes.In the prior art, plants for the synthesis of so-called regenerative kerosine are known, comprising a gasification unit for producing a synthesis gas, an FT reactor connected downstream thereof for producing a HC stream, a cooler and separator connected downstream thereof for cooling and separating the HC stream produced and for producing a Syncrude stream, and a hydrocracker connected downstream thereof for splitting and isomerizing the hydrocarbons and for hydrogenating olefins, so that ultimately a stream of isomerized paraffins is provided. The latter is typically fractionated in a fractionation column in order to be able to discharge fuels as target products in particular.In the prior art, high fractionation costs are required, while the byproducts of the fuel production are also complicatedly further processed. By-products or process exhaust gases are also used individually thermally in order to provide process heat for the own plant or for other plants. In this way, conventional plants regularly achieve a yield of the target product kerosine of below 40%. In other words, the largest proportion of the carbon-containing educts used ultimately does not result in the target product kerosine.SUMMARY OF THE INVENTIONProceeding from the known prior 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 kerosine, for example with an improved yield of kerosine based on the carbon-containing educts used.The object is achieved by a method having the features of claim 1. Advantageous refinements emerge from the dependent claims, the description and the figures.Accordingly, a method is proposed, comprising the following steps:carrying out gasification of carbonaceous educts in order to produce a synthesis gas stream;performing a Fischer-Tropsch reaction using the synthesis gas stream to produce a hydrocarbon stream;cooling and separating the hydrocarbon stream by means of a separator to generate a syncrude stream, the syncrude stream containing, in particular, medium-length and long-chain hydrocarbons;hydrocracking the syncrude stream by means of a hydrocracking apparatus to produce a paraffin stream;fractionating the paraffin stream to produce a kerosine stream and to discharge it as a target product stream and to produce a byproduct stream;returning the by-product stream to the gasification.In the present case, "carbonaceous educts" are understood to mean in particular substances from biomass or waste which are provided for regenerative or sustainable utilization. Furthermore, the carbonaceous educts typically include substances which are easily available from the process engineering standpoint, such as waste gases or flue gases, which are easily accessible for use in a gasification unit.In the present case, the hydrocarbon stream is furthermore understood to mean a stream which comprises hydrocarbon compounds, but which may also comprise, in particular, hydrogen, water, carbon monoxide and / or carbon dioxide. The cooling of the hydrocarbon stream can be effected by means of a cooling unit which is connected upstream of the separator.The syncrud stream may in particular contain medium-length and long-chain hydrocarbons. In the present case, syncrude is understood to mean a synthetic crude oil which can be produced by means of FT synthesis and can be refined further. Thus, Syncrude comprises a hydrocarbon mixture containing, in particular, paraffins and olefins.In the context of the present invention, it has been recognized that the yield of the target product kerosine can be drastically increased with respect to the use of the carbonaceous educts by omitting a purely thermal utilization of waste gases for the purpose of generating process heat. Thus, by-products can be utilized in particular in terms of material instead of a purely thermal utilization.Furthermore, it has been recognized that some or even all by-products can be recycled into the cycle of the process or a corresponding plant, instead of processing them in further processes or plants in a complicated manner from a process standpoint. In this way, a cycle can be created with respect to the exhaust gases and by-products generated in the course of the process or within the plant, so that in the case of a complete recycling of the by-products, the carbon educts used can be converted substantially completely to the target product to be discharged.In the context of the present disclosure, "substantially" means that process-related inaccuracies, fluctuations or leaks are negligible. Thus, in a steady, complete cycle operation of the process or of the plant, a carbon reactant used remains in the cycle of the process engineering process until it is converted to the target product and is consequently discharged.To this end, the present disclosure proposes producing a by-product stream in the course of fractionating the paraffin stream, the by-product stream being recycled and gasified. The by-product stream is thus recycled to the carbon educts. In this way, those educts which are present as byproducts after fractionating and are recycled are not lost to the process, but can be converted by means of the cycle to the target product kerosine. In other words, the disclosed process converts HC byproducts into synthesis gas thanks to the recycling and gasification, which synthesis gas can be converted into the target product kerosine by the downstream FT reaction with the downstream reactions. Thus, the kerosine yield is markedly improved.The synthesis gas or the synthesis gas stream comprises in particular a mixture comprising CO, CO 2, H 2 and H 2 O.Furthermore, the method can comprise the following step: depletion of CO 2 in the synthesis gas stream. The depletion can take place in particular by means of a reverse water gas shift reactor (hereinafter "RWGS") and / or by means of a carbon capture unit. Furthermore, before the depletion, a gas purification of the synthesis gas stream can take place in order to remove or reduce interfering components and / or catalyst poisons. By depleting the CO 2 which acts inertly in an FT reaction, a corresponding FT reactor can be designed and operated more efficiently.Furthermore, the by-product stream may be either gaseous or liquid. For example, only the off-gases can be recycled as a single gaseous by-product stream, while the liquid by-products are otherwise utilized.Furthermore, the liquid by-products can be vaporized after fractionating and be recycled to the corresponding gasification unit separately from the waste gas or together with the latter as a by-product stream.Alternatively, the byproduct stream may comprise a gaseous substream and a liquid substream. The return of the gaseous and the liquid partial stream can be effected separately from one another. The separation of the byproducts and the guidance as partial streams enables different operating variants for the process or the plant.Furthermore, all by-products obtained in the course of fractionating can be recycled in a common by-product stream, in particular via a common recycling line. In this case, the byproducts may include, in particular, exhaust gas, a C3 / C4mixture, and naphtha, and the recirculation may be performed, in particular, in the gaseous state. For example, the corresponding by-product stream can be drawn off easily at the top of the fractionation column, in particular without being condensed. In this way, the fractionation effort can be significantly reduced, since in the range of the C1 to C18 hydrocarbons, only a single separation between the by-product stream and the target product kerosine is required.Further, the method may include:separating off a separator offgas stream which comprises, in particular, CO, H 2, CO 2 and short-chain hydrocarbons;utilizing the substances of the separator exhaust gas stream by means of gasification.The utilization of the substances of the separator exhaust gas stream includes both a direct or intermediate-step-free utilization by means of gasification and a case in which the separator exhaust gas stream is subjected to a further interposed reaction, as will be explained further below with reference to an interposed pre-reformer. Thanks to the utilization of the waste gas stream, the proportion of carbon educts in the cycle can be further increased.Further, the step of fractionating the paraffin stream may comprise: generating and discharging a diesel stream as another target product stream.Additionally or alternatively, the step of fractionating the paraffin stream may comprise: producing a further byproduct stream; and feeding the further byproduct stream to the hydrocracker. In particular, the further by-product stream can comprise diesel. For example, a first fraction of diesel can be discharged in the form of the further target product stream and a second fraction of diesel can be fed back to the circuit. In this way, a desired target quantity of diesel can be produced very easily, wherein the diesel excess is utilized in the circuit. The quantity of diesel to be discharged as a further target product can thus be regulated in a simple manner, in particular via regulation of valves or flow rates, so that additional changes in further process engineering parameters of the reactors are not required. For example, pressure and / or temperature of reactions need not be adjusted to affect the equilibrium reactions to control the yield of diesel.Furthermore, the further by-product stream may comprise, in particular, long-chain paraffins, for example waxes. In addition, the further by-product stream can comprise separated substreams of the long-chain paraffins and of the diesel in separate lines.Furthermore, the by-product stream can consist essentially of hydrocarbons having a chain length in the range C1 to C7.Additionally or alternatively, the further by-product stream may comprise long-chain paraffins, in particular in the form of waxes. Furthermore, the further by-product stream may comprise diesel.Further, the method may comprise: reforming the byproduct stream using a pre-reformer to increase a methane content of the byproduct stream. Thanks to the increased methane content in the byproduct stream, the gasification or operation of a gasification unit can be simplified.A "pre-reformer" is understood in the present case as a reactor unit which is also referred to in the prior art as a pre-reformer and is typically always used in conjunction with a main reactor unit for steam reforming or for autothermal reforming (ATR). Accordingly, in the pre-reformer, heavier hydrocarbons such as naphtha or light hydrocarbons are converted into lighter components such as methane, hydrogen, carbon monoxide and carbon dioxide.Furthermore, the method can comprise the following step: inerting a plant which is configured to carry out the method in order to purge air which has entered the plant out of the plant by means of a purge gas, wherein the purge gas is CO 2, steam or a sequential combination of nitrogen and methane. The air to be purged may have entered the installation in particular during startup or re-startup of the installation.In the present case, a sequential combination of nitrogen and methane is understood to mean that it is possible to initially flush with nitrogen and the nitrogen can subsequently be displaced by methane. In this case, the generated nitrogen-methane exhaust gas may be burned via a torch.Thanks to the inertization described above, process-specific inert gases can be replaced by process-specific gases. In particular, it can be ensured that inert gases, for example nitrogen, which may be introduced temporarily, are displaced from the plant before the continuous intended method or operation of the corresponding plant is started. In this way, it can be achieved that no inert gases that are foreign to the process accumulate over time, which would impede the complete utilization of the waste gas streams according to the above description. In other words, the risk of an accumulation of inert gases in the above-described gas circuit can be largely ruled out.Furthermore, the method can comprise the following steps:generating electrolysis hydrogen as an additional reactant by means of an electrolysis unit;separating a water condensate by means of the separator;preparing the water condensate, in particular by means of biological preparation using reverse osmosis; andsupplying the water condensate as deionized water to the electrolysis unit.In this way, the ion-free water which is produced in the separator as waste water can be used for the purposes of a circuit for the method or the corresponding plant. Thus, less water needs to be separately deionized for operation of the electrolysis unit. In this way, the process or the plant can be operated even more continuously.The object set out above is furthermore achieved by a system having the features of claim 11. Advantageous refinements of the system are evident from the dependent claims, the description and the figures. Accordingly, a regenerative kerosine synthesis plant is proposed, comprising a gasification unit, a Fischer-Tropsch reactor, a separator, a hydrocracker and a fractionation column. The plant additionally comprises a feed line, by means of which an outlet side of the fractionation column is connected to a reactant side of the gasification unit.In particular, a cooling unit for cooling the hydrocarbon stream can be connected upstream of the separator.The definitions, technical effects and advantages explained above for the method according to the disclosure apply equally correspondingly to the proposed plant. In particular, the chemical and structural components and technical units described in the context of the method correspond to the same-name chemical and structural components and technical units described in the context of the proposed installation.Furthermore, the plant may have at least one target product discharge and a substantially closed circuit for carbonaceous byproducts. For example, the plant may have a first target product discharge for kerosine and a second target product discharge for diesel. Thanks to the substantially closed circuit for carbonaceous byproducts, the lighter byproducts in the range of a HC chain length C1-C7can be returned to the gasification unit, while the heavy byproducts in the range >C20can be returned to the hydrocracker after the fractionation column. In this way, the target product yield can be increased considerably.Furthermore, the plant can comprise a reverse water gas shift reactor and / or a carbon capture unit in order to de-enrich CO 2 in the synthesis gas stream.Furthermore, the plant can comprise a pre-reformer, which is connected downstream of the fractionation column and by means of the feed line to the gasification unit, in order to increase a methane content of the byproduct stream.Furthermore, the plant can have an electrolysis unit, wherein the separator is connected to the electrolysis unit in order to supply the electrolysis unit with deionized water.Brief Description of the FiguresExemplary embodiments of the invention are explained in more detail by the following description of the figures. The following are shown schematically: FIG. 1 is a flow chart of a regenerative kerosine synthesis method according to a first embodiment; FIG. 2 shows a flow diagram of the method according to further embodiments; FIG. 3 shows an embodiment of a plant for the synthesis of regenerative kerosine according to an embodiment; and FIG. 4 shows a further embodiment of the plant from FIG. 3.DETAILED DESCRIPTION OF EMBODIMENTSIndividual exemplary embodiments are described below with reference to the figures. Identical, similar or identically acting elements are provided with identical reference symbols in the different figures, and a repeated description of these elements is partly omitted in order to avoid redundancies.For better understanding, the method steps described in connection with FIGS. 1 and 2 are additionally represented with corresponding reference numerals in FIGS. 3 and 4.FIG. 1 schematically shows a flow chart of a method for synthesizing regenerative kerosine according to a first embodiment. As can be seen from FIGS. 1 and 3, the method comprises the following steps:performing S 10 a gasification of carbon educts in order to produce a synthesis gas stream 12;performing S20 a Fischer-Tropsch reaction using the synthesis gas stream 12 to produce a hydrocarbon stream 14;cooling and separating S 30 the hydrocarbon stream 14 by means of a separator 30 in order to generate a syncrude stream 16, the syncrude stream 16 containing, in particular, medium-length and long-chain hydrocarbons;hydrocracking S40 of the syncrude stream 16 by means of a hydrocracking unit 40 to produce a paraffin stream 18;fractionating S50 the paraffin stream 18 to produce a kerosine stream 22 and to discharge it as the target product stream 22 and to produce a byproduct stream 24;returning S70 the byproduct stream 24 to the gasification.FIG. 3 shows an embodiment of a plant 1 for the synthesis of regenerative kerosine. The plant 1 includes a gasification unit 10 for performing step S 10; a Fischer-Tropsch reactor 20 for performing step S 20; a cooling unit (not shown) and the separator 30 for performing step S 30; the hydrocracker 40 for performing step S 40; and a fractionation column 50 for performing step S 50. The plant 1 additionally comprises a feed line 70, by means of which an outlet side 51 of the fractionation column 50 is connected to a reactant side 10 aof the gasification unit 10.In order to avoid repetition, reference is made to the above description with regard to the technical effects and the definitions and abbreviations used. The method and the plant 1 are explained in more detail below first with reference to FIGS. 1, 2 to 3.In the gasification unit 10, in step S 10, the carbon educts, in particular C-H-O compounds, are converted into synthesis gas using electrolysis oxygen and water vapor. Depending on the composition of the carbon educts, in particular their ratios of C, H and O compounds, as well as depending on oxygen and water vapor 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: C-H-O substances + H 2 O + O 2 → CO / CO 2 / H 2 / H 2 O mixture (1)The gasification unit 10 additionally comprises a gas purification unit for purifying the synthesis gas stream 12, in particular for removing or reducing interfering components and / or catalyst poisons.In a step S 15, CO 2 in the synthesis gas stream 12 can be depleted. The depletion can be effected by means of a carbon capture unit 15 b, wherein the depleted CO 2 can be fed back to the gasification unit 10, where it can be used as a barrier gas. In one variant, the CO 2- depleted synthesis gas stream 12 can subsequently be fed directly to the FT reactor 20.Alternatively, a reverse water gas shift reactor 15 acan be connected downstream of the carbon capture unit 15 bfor further depletion of CO2, wherein the synthesis gas stream 12 can subsequently be fed to the FT reactor 20. The reverse water gas shift reactor 15 acan be supplied with regenerative hydrogen from an electrolysis unit 38 which, according to a step S 8, generates electrolysis hydrogen as additional reactant.The RWGS reaction according to step S 15 is endothermic and may be carried out at an RWGS temperature in the range 800 to 1000° C. In this way, the RWGS equilibrium can be shifted to the desired RWGS product CO according to the following equation: CO 2+ H 2 ↔ CO+H 2 O (2)Further, both the carbon capture unit 15 band the RWGS reactor 15 amay be connected between the gasification unit 10 and the FT reactor 20, as illustrated in FIG. 3. In this case, the carbon capture unit 15 bpreviously serves to recover smaller amounts of CO 2 from the synthesis gas stream to provide them to the gasification unit 10 as a barrier gas. Thus, much of the CO 2 remains behind the carbon capture unit 15b in the synthesis gas stream 12 and the RWGS reactor 15a causes the substantial portion of the CO 2- depletion.On the reactant side, H 2 in molar excess and CO 2, for example approximately in the ratio 3:1, are fed to the RWGS reactor 15a. On the product side, the unreacted CO 2 and the excess H 2 are also present downstream of the RWGS reactor 10, so that the synthesis gas stream 12 reacted by the RWGS reactor 15 acomprises a gas mixture comprising CO 2, H 2, CO and H 2 O. Condensed water can optionally be discharged.The synthesis gas stream 12 is then fed to the FT reactor 20 for carrying out step S 20, in which reactor a hydrocarbon stream 14 is produced at an FT temperature in the range from 250 to 300° C. on the heterogeneous catalyst. The heterogeneous catalyst can in particular be a cobalt- or iron-based catalyst. Hydrocarbon stream 14 is a mixture of hydrocarbons, especially olefins and paraffins, with a very broad distribution of HC chains typically for the FT reaction. In addition to the paraffin-olefin mixture, residues of the unconverted gases CO 2, H 2 and CO and unconverted reaction water are also present in the hydrocarbon stream 14.The following equations (3) and (4) describe the product formation in the FT reactor 20 and according to step S 20:Olefin formation: n CO+2nH2→(CH 2) n+nH2O (3)Paraffin formation: n CO + (2n+1) H2→ H- (CH 2) n-H + n H2O (4)In step S 30, 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 by means of cooling the gaseous hydrocarbon stream 14, water and medium-length and long-chain hydrocarbons are condensed out. In contrast, the gaseous hydrocarbons of the unconverted educts remain gaseous. The mixture of condensed substances breaks down into two phases, which are separated in the separator 30.At the bottom of the separator 30, a water condensate 42 can be drawn off due to its higher density. Since the water condensate 42 is deionized, it can be processed in a step S 35 and supplied in a step S 36 to the electrolysis unit 38 so that electrolysis hydrogen is generated in the step S 8 for the step S 10, which uses deionized water from the cycle of the disclosed method or the plant 1 (see FIGS. 2 and 3 ). The processing can be carried out by means of a processing plant 37, for example a biological processing in conjunction with a reverse osmosis.Referring again to step S 30, the mixture of the medium-length and long-chain hydrocarbons is obtained in the separator 30 as a further liquid phase in the form of the syncrud flow 16.The syncrud stream 16 is now fed to the hydrocracker 40 together with gaseous hydrogen. In hydrocracking S40, long-chain hydrocarbons, in particular having a chain length of >C20, for example waxes, are cleaved into shorter and medium-length hydrocarbons.Furthermore, in the hydrocracker 40, the HC chains formed in unbranched form in the FT reactor 20 are isomerized by means of the introduction of side chains. In addition, the olefins are hydrogenated. Thus, a mixture of isomerized paraffins having shorter and medium chain lengths is formed which is passed as paraffin stream 18 to fractionation column 50. The paraffin stream 18 furthermore contains waxes, i.e. long-chain hydrocarbons, since their conversion during the cleavage in the hydrocracker 40 is not complete.In the fractionation step S50, the paraffin stream 18 is separated into fractions by distillation. According to the disclosure, at least the kerosine stream 22 and the by-product stream 24 are produced as fractions. The byproduct stream 24 may consist essentially of hydrocarbons having a chain length in the range C1 to C7. The term "substantially" as used herein means that hydrocarbons having a chain length of C8or more may also be present singly or within a negligible scope.In addition, a further by-product stream 34 comprising long-chain paraffins, in particular waxes, can be produced (step S 54), which can be fed to the syncrude stream 16 or the hydrocracking unit 40 (step S 56), such that the further by-product stream 34 is again subjected to hydrocracking S 40 and thus remains in the circuit of the process or the plant 1.In step S 70, the by-product stream 24 is supplied to the gasification unit 10 via a supply line 70. As can be seen in FIG. 3, the feed line 70 can comprise a plurality of individual lines 70 for returning the by-product stream 24 or its individual partial streams 24 a, 24 b, 24 c. For example, a first substream 24 amay include an HC exhaust gas, a second substream 24 bmay include C3-C4hydrocarbon, and a third substream 24 cmay include naphtha. In this case, the fractionation products are separately supplied to a pre-reformer 60. Alternatively, the fractionation products may be supplied to the pre-reformer 60 in a common feed line 70.Further, as described above, the output side 51 of the fractionation column 50 is connected to the reactant side 10 aof the gasification unit 10 via the feed line 70. Here, the supply line 70 may be interrupted by the pre-reformer 60, as shown in FIG. 3, or may extend uninterruptedly from the fractionation column 50 to the gasification unit 10. In other words, the feed line 70 can connect the outlet side 51 of the fractionation column 50 directly to the reactant side 10 aof the gasification unit 10 (not illustrated in FIG. 3 ).Thus, the feed line 70 essentially has the function of conducting the by-product stream 24, or its individual partial streams 24 a, 24 band 24 c,from the fractionation column 50 to the gasification unit 10, regardless of whether the pre-reformer 60 is interposed or not.In the optionally interposed pre-reformer 60, the by-product stream 24 is reacted with addition of water vapor at temperatures between 250 and 500° C. over the heterogeneous catalyst according to the following equation (5) to increase a methane content of the by-product stream (24) (step S 60):Pre-reforming: C n H m+ x H 2 O→CH 4 / CO / CO 2 / H 2 / H 2 O (5)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.Reforming S 60 in pre-reformer 60 according to reaction equation (4) above is endothermic or exothermic depending on the product ratio. More specifically, the reaction is slightly endothermic when more CO than CO 2 is formed in addition to CH 4 or slightly exothermic when more CO 2 than CO is formed in addition to CH 4 respectively. The pre-reformer 60 can be operated adiabatically in particular. Thus, a reacting gas mixture heats up in the case of an exothermic reaction, or cools down in the case of an endothermic reaction.In the separator 30, a separator exhaust gas flow 28 may be separated (step S 32). The separator exhaust gas stream 28 contains in particular CO, H 2, CO 2 and short-chain hydrocarbons, and is optionally fed to the pre-reformer 60 and reformed in order to increase the methane content of the separator exhaust gas stream 28, and is then fed via the feed line 70 to the gasification unit 10, so that ultimately the substances of the separator exhaust gas stream 28 are used by means of the gasification (step S 72), as illustrated in FIG. 3. In this way, the yield of the target product can be further increased.Alternatively, the separator exhaust gas stream 28 can be supplied directly to the gasification unit 10 without using the pre-reformer 60, so that the substances of the separator exhaust gas stream 28 are used directly by means of gasification (step S 72). In this way, the yield of the target product can be further increased.FIG. 2 schematically shows a flow diagram of the method according to further embodiments. In particular, FIG. 2 shows individual refinements which can be applied alone or in combination with one another for the method according to the disclosure or for the installation 1.The exemplary development of the recycling of the deionized water condensate 42 from the separator 30 according to steps S 33, S 35, S 36, S 8 and S 10 has already been described with reference to FIG. 3. The same applies to the exemplary development of the recycling of the further by-product stream 34 according to steps S 50, S 54, S 56 and S 40, which has likewise been described with reference to FIG. 3. The same applies to the exemplary development of the cycle utilization of the separator exhaust gas stream 28 according to steps S 30, S 32 and S 72, which has likewise been described with reference to FIG. 3.According to a further exemplary development, as substep of step 50, fractionating in a step S 52, a diesel stream 32 is generated and discharged from the process or the plant 1 in the form of a further target product stream 32 (see FIG. 2 ).Alternatively, the diesel stream 32 can be produced in the fractionation column 50 and fed completely or partially, in particular by means of a controllable branching, to the further by-product stream 34.In this way, a desired amount of diesel can be produced as a further target product, wherein an excess of diesel can be used in the cycle. The quantity of diesel to be diverted can thus be regulated without further process parameters of the reactors of the plant 1 having to be changed.Fig. 4 shows a further embodiment of the plant 1 of Fig. 3. In this example, the kerosine stream 22 is discharged as the only target product. Diesel resulting from the fractionation is recycled to hydrocracking S40 together with the further by-product stream in step S54.Furthermore, the plant 1 according to the example shown in FIG. 4 has neither the pre-reformer 60 nor the RWGS reactor 15 a. Correspondingly, the separator offgas stream 28 is returned directly to the reactant side 10 aof gasification unit 10. Furthermore, the electrolysis hydrogen is conducted from the electrolysis unit to the FT reactor 20 accordingly.In addition, the recycling S 70 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 to the reactant side 10 aof the gasification unit 10.The exemplary embodiment according to FIG. 4 is distinguished by a very low outlay on apparatus, while at the same time the above-described circulation batch for the method or the plant 1 can be implemented to a very high degree.Where applicable, all individual features illustrated in the exemplary embodiments can be combined with one another and / or interchanged without departing from the scope of the invention. For example, individual optional refinements according to the exemplary embodiment of FIG. 3 can be used in the exemplary embodiment according to FIG. 4. This relates in particular to the further target product stream 32 for diesel, the intermediate connection of the pre-reformer 60, and the provision of the RWGS reactor 10.

Claims

A process for the synthesis of regenerative kerosine (22), comprising the following steps: - carrying out (S10) a gasification of carbonaceous educts to produce a synthesis gas stream (12); - carrying out (S20) a Fischer-Tropsch reaction using the synthesis gas stream (12) to produce a hydrocarbon stream (14); - cooling and separating (S30) the hydrocarbon stream (14) by means of a separator (30) to produce a syncrude stream (16), wherein the syncrude stream (16) contains in particular medium-length and long-chain hydrocarbons; - hydrocracking (S40) the syncrude stream (16) by means of a hydrocracking unit (40) to produce a paraffin stream (18); fractionating (S50) the paraffin stream (18) in order to generate a kerosine stream (22) and to discharge it as a target product stream (22) and in order to generate a by-product stream (24); characterized by recirculating (S70) the by-product stream (24) to the gasification.The method according to claim 1, comprising the following step: - depleting (S15) CO 2 in 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).The process of claim 1 or 2, wherein the byproduct stream (24) is either gaseous or liquid.The method according to claim 1 or 2, wherein the by-product stream comprises a gaseous sub-stream and a liquid sub-stream, in particular wherein the recycling (S70) of the gaseous and the liquid sub-stream takes place separately from each other.Method according to one of the preceding claims, further comprising: - separating (S32) a separator waste gas stream (28) which in particular contains CO, H 2, CO 2 and short-chain hydrocarbons; - using (S72) the substances of the separator waste gas stream (28) by means of the gasification.The method according to any of the preceding claims, wherein the step of fractionating (S50) the paraffin stream (18) comprises: - generating and discharging (S52) a diesel stream (32) as a further target product stream (32); and / or - generating (S54) a further byproduct stream (34) and supplying (S56) the further byproduct stream (34) to the hydrocracker (40).The method according to any one of the preceding claims, wherein the byproduct stream (24) consists essentially of hydrocarbons having a chain length in the range C1 to C7, and / or wherein the further byproduct stream (34) contains long-chain paraffins, in particular in the form of waxes, and optionally diesel.The method according to any of the preceding claims, further comprising: - reforming (S60) the byproduct stream (24) by means of a pre-reformer (60) to increase a methane content of the byproduct stream (24).Method according to one of the preceding claims, further comprising: - inerting (S5) a plant (1) which is set up for carrying out the method in order, in particular during startup or re-startup of the plant (1), to flush air which has entered the plant (1) out of the plant (1) by means of a flushing gas, wherein the flushing gas CO 2, is steam or a sequential combination of nitrogen and methane.Method according to one of the preceding claims, further comprising: - generating (S8) electrolysis hydrogen as additional reactant by means of an electrolysis unit (38); - separating (S33) a water condensate (42) by means of the separator (30); - treating (S35) the water condensate (42), in particular by means of biological treatment using reverse osmosis; and - supplying (S36) the water condensate (42) as deionised water to the electrolysis unit (38).Plant (1) for the synthesis of regenerative kerosine (22), comprising a gasification unit (10), a Fischer-Tropsch reactor (20), a separator (30), a hydrocracker (40) and a fractionation column (50), characterized bya 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).Plant (1) according to claim 11, comprising at least one target product discharge (22, 32) and a substantially closed circuit for carbonaceous byproducts.Plant (1) according to claim 11 or 12, comprising a reverse water gas shift reactor (15a) and / or a carbon capture unit (15b) for depleting CO 2 in the synthesis gas stream (12).Plant (1) according to any one of claims 11 to 13, comprising a pre-reformer (60) which is connected downstream of the fractionation column (50) and by means of the feed line (70) to the gasification unit (10) in order to increase a methane content of the byproduct stream (24).

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