Production of a synthetic oil
The method addresses hydrogen availability fluctuations by separating components in the Fischer-Tropsch reaction, enabling continuous synthetic oil production and stabilizing reactant supply through storage and adjustment, thus preventing equipment damage.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- RWE POWER AKTIENGESELSCHAFT
- Filing Date
- 2026-01-07
- Publication Date
- 2026-07-16
AI Technical Summary
Chemical processes for producing synthetic kerosene face challenges due to fluctuations in the availability of hydrogen, which can lead to equipment damage if not operated continuously within permissible load ranges.
A method involving a Fischer-Tropsch reaction using carbon monoxide and hydrogen as starting materials, with a separation process to divide a lighter component from the crude product, allowing for continuous operation by storing excess hydrogen for later use and adjusting reactant generation based on availability.
Ensures continuous production of synthetic oil, minimizing equipment damage by maintaining a minimum capacity and utilizing stored hydrogen to stabilize reactant supply, even with fluctuating hydrogen availability.
Smart Images
Figure EP2026050195_16072026_PF_FP_ABST
Abstract
Description
[0001] Production of a synthetic oil
[0002] The invention relates to a process for producing a synthetic oil. This synthetic oil can, in particular, be further processed into synthetic kerosene. To date, kerosene is primarily produced as a mineral product derived from fossil raw materials. To become independent of these finite resources, efforts are underway to produce synthetic kerosene that is non-mineral. Known solutions use hydrogen as a starting material. Hydrogen can be produced, in particular, by electrolysis. This is especially advantageous when the electrolysis is powered by renewable energy. In this case, it can be said that the electrolysis is powered by green electricity. The hydrogen obtained in this way can be referred to as green hydrogen. However, renewable energy sources are naturally subject to fluctuations.It follows that the availability of green hydrogen also fluctuates accordingly; however, chemical processes for the production of synthetic kerosene cannot simply be shut down or operated according to the fluctuations of renewable energies. It is therefore desirable that the process can run continuously within the permissible load range. Otherwise, damage to the equipment used may occur. The difficulties described for synthetic kerosene also apply to the production of other substances. It is irrelevant whether the availability of hydrogen fluctuates, as described, due to the use of renewable energies or for some other reason.
[0003] The object of the present invention is therefore to present a method for producing a synthetic oil which can be operated reliably even when the availability of hydrogen fluctuates.
[0004] This problem is addressed by the inventive process for producing a synthetic oil. The process comprises:
[0005] a) Providing carbon monoxide and hydrogen as reaction starting materials, b) Producing a crude product from the reaction starting materials provided in a) by means of a Fischer-Tropsch reaction,
[0006] c) Separating at least one component from the crude product obtained in b) so that the synthetic oil remains, wherein the separated component has a lower density than the synthetic oil,
[0007] where in a first operating mode
[0008] ■ the component separated from the raw product in c) is divided into a first fraction and a second fraction, wherein the density of the first fraction is lower than the density of the second fraction,
[0009] ■ the carbon monoxide is produced in a) partly from provided carbon dioxide and hydrogen and partly from the first part of the component separated from the raw product in c),
[0010] ■ the second part of the component separated from the crude product in c) is stored as a storage substance,
[0011] where in a second operating mode
[0012] ■ the reaction reactants in a) are at least partially generated from the storage substance stored in the first operating mode.
[0013] The described process produces a synthetic oil. This can be, in particular, synthetic crude oil. It can also be referred to as "Syncrude." The synthetic oil is produced from non-mineral raw materials using the described process. It can therefore also be called a non-mineral oil. The chemical composition of the synthetic oil results from the steps of its production described below. Beyond this, the chemical composition of the synthetic oil is not essential. In particular, the synthetic oil can comprise a mixture of various hydrocarbons. Specifically, the synthetic oil can contain linear or branched alkanes.
[0014] The synthetic oil itself can be the end product of the process. However, the process can also include further processing steps for the synthetic oil. All conventional steps that can also be used for processing mineral crude oil are suitable for this purpose. For example, the synthetic oil can be converted in a further processing step into naphtha (which can also be called "chemical gasoline" or "crude gasoline"), middle distillates (MD for short), wax, and / or kerosene. The kerosene obtained in this way can be called synthetic kerosene. This kerosene can be, in particular, so-called "drop-in kerosene." This is kerosene that can be used in existing jet engines. Drop-in kerosene is typically blended with conventional, i.e., mineral, kerosene, for example, by up to 50%.Insofar as the described process also includes the further processing of the synthetic oil, the process can also be referred to as a "process for the production and further processing of a synthetic oil". In a), carbon monoxide and hydrogen are provided as reactants. These reactants can be generated as part of the process or used as readily available starting materials. The reactants can, in particular, be provided as a mixture. This mixture can be referred to as a synthesis gas. The reactants are preferably gaseous.
[0015] In step b), a crude product is generated from the reactants provided in step a) via a Fischer-Tropsch reaction. The result is a mixture of various substances, including, in particular, hydrocarbons of different chain lengths. The crude product may also contain unreacted reactants, such as carbon monoxide and hydrogen. The generation of the crude product in step b) is preferably carried out in a Fischer-Tropsch reactor.
[0016] A Fischer-Tropsch reaction cannot simply be ramped up and down. It is desirable that the Fischer-Tropsch reaction be operated continuously at least at a minimum capacity. Otherwise, damage, particularly to the Fischer-Tropsch reactor, can occur. It is therefore preferred that the described process be carried out continuously for a period of at least one day, preferably even at least one month. The capacity of the Fischer-Tropsch reaction preferably never falls below the minimum capacity. The minimum capacity is set such that the process can be assumed to be carried out without damage at this level. The minimum capacity is preferably in the range of 40 to 80%, particularly in the range of 50 to 70%, for example, at 60%.This refers to the maximum utilization of the Fischer-Tropsch reaction, which by definition corresponds to 100%.
[0017] In step c), at least one component is separated from the crude product obtained in step b), leaving the synthetic oil. The separated component has a lower density than the synthetic oil. The separated component can therefore also be described as a lighter component or a volatile component. The separated component preferably consists of substances that are gaseous under normal conditions. The remaining part of the crude product preferably consists of substances that are liquid under normal conditions. The state of matter under the actual conditions is irrelevant. The separation in step c) can therefore consist of separating a gas phase and a liquid phase of the crude product. However, a precise separation of the gas and liquid phases is not required.The described procedure can also be successfully carried out with a slightly different boundary between the components. Therefore, the focus here is generally on densities.
[0018] The separated component contains hydrocarbons. For example, the separated component may include carbon monoxide, hydrogen, methane, propane, and butane.
[0019] In addition to the previously considered separated component, one or more further components can also be separated in c). In particular, water can be separated as a further component when separating the previously considered component. The density of the further components is irrelevant. Therefore, the further components can have a higher, the same, or a lower density compared to the previously considered separated component and compared to the synthetic oil.
[0020] The separation of at least one component from the crude product in c) preferably takes place in a first separation device. The separation can be carried out in a conventional manner. The density difference between the separated component and the synthetic oil can be utilized in this process.
[0021] The arrangement can be operated in different operating modes. These differ particularly in how the carbon monoxide, as one of the reaction reactants in a), is provided.
[0022] In a first operating mode, the component separated from the crude product in c) is divided into a first fraction and a second fraction. The density of the first fraction is lower than that of the second fraction. The first fraction can also be referred to as the light fraction, while the second fraction is referred to as the heavy fraction. The division preferably takes place in a second separation unit. The second fraction can, in particular, be a mixture of propane and butane. The second fraction can have a composition similar to liquefied petroleum gas (LPG, also known as autogas). However, the second fraction can also include substances that, according to the conventional definition, do not fall under the term LPG. The second fraction can therefore also be referred to as LPG+. The first fraction is the remaining residue of the component separated from the crude product in c).The first component can include, in particular, carbon monoxide, hydrogen, methane and other hydrocarbons.
[0023] Furthermore, in the first operating mode, the carbon monoxide is generated in a) partly from supplied carbon dioxide and hydrogen and partly from the first fraction of the component separated from the crude product in c). The carbon monoxide used as one of the reaction reactants is therefore generated partially in at least two ways.
[0024] Firstly, carbon monoxide is generated from supplied carbon dioxide and hydrogen. The carbon dioxide used for this purpose is preferably supplied to an arrangement used in the described process via a carbon dioxide feed. The source of the supplied carbon dioxide is generally irrelevant for the process considered herein. However, it is preferred that the carbon dioxide originates from combustion, in particular from biological material such as sewage sludge. Using carbon dioxide from combustion is simpler than extracting carbon dioxide from, for example, the ambient air. If the carbon dioxide originates from the combustion of biological material, the carbon dioxide has previously been removed from the atmosphere, which is advantageous for the overall carbon dioxide balance of the process. The source of the supplied hydrogen is also generally irrelevant for the process considered herein.However, the hydrogen is preferably produced using renewable energy sources, for example via electrolysis. This is also beneficial for the overall carbon dioxide balance of the process. The hydrogen supply can fluctuate. This is particularly, but not exclusively, the case when using green hydrogen from electrolysis powered by renewable energy. For the process described herein, the cause of these fluctuations is generally irrelevant. As described below, the fluctuations in hydrogen availability can generally be compensated for using the described process.
[0025] The hydrogen used is preferably supplied to an arrangement employed in the described process via a hydrogen feed. The carbon monoxide is thus preferably generated partly from carbon dioxide supplied via a carbon dioxide feed and partly from hydrogen supplied via a hydrogen feed. In general, the described process can be particularly climate-friendly, especially through appropriate selection of the sources for the carbon dioxide and the hydrogen.
[0026] Carbon monoxide can be produced from carbon dioxide and hydrogen, in particular via the so-called reverse water-gas shift (RWGS) reaction:
[0027] CO2 + H2CO + H2O
[0028] The carbon monoxide is preferably generated from the carbon dioxide and hydrogen in a RWGS reactor. Generally, it can be assumed that the hydrogen does not react completely in the RWGS reactor. Therefore, hydrogen is also discharged from the RWGS reactor. This hydrogen, together with the carbon monoxide, can form the reactants for the Fischer-Tropsch reaction. In general, the hydrogen used as one of the reactants for the Fischer-Tropsch reaction can be supplied to the Fischer-Tropsch reactor in any desired manner. In particular, the hydrogen used as one of the reactants for the Fischer-Tropsch reaction can originate from the hydrogen supply. The carbon monoxide thus obtained is preferably fed to the Fischer-Tropsch reaction together with the hydrogen that did not react in the RWGS reaction. For this purpose, the carbon monoxide and the hydrogen can be introduced into the Fischer-Tropsch reactor together.
[0029] The water produced during the RWGS reaction can be discharged as wastewater. However, it is not essential that the carbon monoxide is generated from the carbon dioxide and hydrogen via the RWGS reaction. The method used is irrelevant to the fundamental operation of the described process. The only crucial point is that the carbon monoxide is produced from carbon dioxide and hydrogen.
[0030] Secondly, carbon monoxide is produced from the first fraction of the component separated from the crude product in step c). This can be achieved, in particular, by steam reforming. For example, methane contained in the first fraction can be reacted with the following chemical reactions:
[0031] CW4 + H2O CO + 3H2
[0032] Other components of the first fraction can be converted in a similar manner. However, it is not necessary for the first fraction to be completely converted by steam reforming.
[0033] The steam required for steam reforming can be supplied in various ways. For example, it could be water that is separated from the raw product by the first separation unit as a further component. This reuse is energy-efficient and makes sense in terms of the raw materials used. However, this is not necessary for the basic function of the described process. The water can also simply be taken as fresh water from the mains supply. It is not essential, however, that the carbon monoxide be generated from the first fraction of the component separated from the raw product in step c) by means of steam reforming. The method used is irrelevant to the basic functionality of the described process. The only crucial point is that the carbon monoxide is generated from the first fraction of the component separated from the raw product in step c).
[0034] In any case, according to a), the reactants carbon monoxide and hydrogen are available for further use. This can be the case, in particular, in the form of a mixture. This mixture is preferably fed to the Fischer-Tropsch reaction. For this purpose, this mixture can be introduced into the Fischer-Tropsch reactor. Alternatively, it is also conceivable – although practically inconvenient – to introduce the reactants separately into the Fischer-Tropsch reactor.
[0035] Furthermore, in the first operating mode, the second portion of the component separated from the raw product in c) is stored as a storage substance. This is preferably done in a storage device, preferably a tank. The storage substance is preferably stored in liquid form, for example at a pressure of 4 bar. This is particularly energy-efficient. The storage substance is stored in the first operating mode to be available for other operating modes. In particular, the storage substance can be accessed when insufficient hydrogen is available via the hydrogen supply. This can be the case, for example, when renewable energies are only available to a limited extent due to weather conditions.
[0036] In a second operating mode, the reactants in a) are at least partially generated from the storage substance stored in the first operating mode. This can be done in various ways, as explained in more detail below. The basic functionality of the process described herein is unaffected by which of these methods is chosen.
[0037] Crucially, in the second operating mode, the reactants must be at least partially derived from the stored storage substance. In the extreme case, the reactants in the second operating mode are derived exclusively from the stored storage substance. In this case, no hydrogen from the hydrogen supply is required at all. The second operating mode can therefore also be used when no renewable energies are available. However, in the second operating mode, it is also possible, and even preferred, for the reactants to be derived partly from the stored storage substance and partly from provided carbon dioxide and hydrogen. The same applies to the latter as described for the first operating mode. Additionally, some of the reactants can also be derived from the component separated from the crude product in section c). The same applies to this as described for the first operating mode.
[0038] In the second operating mode, preferably no storage substance is stored. This would be counterproductive, as the storage substance would, on the contrary, be taken from the storage. Therefore, in the second operating mode, the component separated from the crude product in c) is preferably not divided into a first fraction and a second fraction, with the density of the first fraction being lower than the density of the second fraction. This division is not necessary. However, since this division is generally not detrimental, it is not impossible that this division nevertheless occurs. If the second fraction of the component separated from the crude product in c) were to be formed in the second operating mode, it would preferably not be stored as the storage substance.
[0039] In all operating modes, a portion of the component separated from the crude product in c) can be directly reintroduced into the Fischer-Tropsch reaction and thus recycled. If the component separated from the crude product in c) is divided into a first fraction and a second fraction, with the density of the first fraction being lower than the density of the second fraction, this can, in particular, be a portion of the first fraction of the component separated from the crude product in c).
[0040] Recycling can increase the yield of the Fischer-Tropsch reaction. The yield is primarily determined by the conversion rate of the Fischer-Tropsch reaction. Furthermore, in all operating modes, a portion of the component separated from the crude product in step c) can be removed from the arrangement used for the process. If the component separated from the crude product in step c) is divided into a first fraction and a second fraction, with the density of the first fraction being lower than the density of the second fraction, this can, in particular, be a portion of the first fraction of the component separated from the crude product in step c). This removal can prevent the accumulation of, for example, nitrogen in the lines of the arrangement.
[0041] Furthermore, in all operating modes, a portion of the component separated from the crude product can be used to provide thermal energy for steam reforming in the steam reformer. Insofar as the component separated from the crude product in c) is divided into a first fraction and a second fraction, with the density of the first fraction being lower than the density of the second fraction, this can, in particular, be a portion of the first fraction of the component separated from the crude product in c).
[0042] Furthermore, a portion of the first fraction of the component separated from the crude product can be used to provide thermal energy for the reaction in the RWGS reactor – provided the RWGS reactor is used in the respective operating mode. Insofar as the component separated from the crude product in c) is divided into a first fraction and a second fraction, with the density of the first fraction being lower than the density of the second fraction, this can, in particular, be a portion of the first fraction of the component separated from the crude product in c).
[0043] In a preferred embodiment of the method, in the first operating mode, the hydrogen used for the production of carbon monoxide is at least partially generated by electrolysis powered by renewable energies.
[0044] In this embodiment, hydrogen, which can be described as green hydrogen, is supplied to the arrangement used for the process via the hydrogen supply. In this respect, the described process is particularly climate-friendly. The fact that the hydrogen supply is subject to fluctuations when using renewable energies for hydrogen production can be compensated for by the described process, particularly via the storage substance, as described herein.
[0045] In another preferred embodiment, the process is only carried out in the first operating mode if the availability of hydrogen from electrolysis is at least at a predetermined limit.
[0046] The utilization rate of the Fischer-Tropsch reaction should preferably not fall below a minimum value. Otherwise, damage to the Fischer-Tropsch reactor could occur. The minimum value is, for example, 60%. This is based on a full utilization rate of the Fischer-Tropsch reactor, which by definition corresponds to 100%. The 60% utilization rate can also be referred to as the "turndown" capacity of the Fischer-Tropsch reactor.
[0047] If the Fischer-Tropsch reaction is fed exclusively with hydrogen from electrolysis, the utilization rate of the Fischer-Tropsch reaction is proportional to the availability of hydrogen from electrolysis. The specified limit value is therefore sensibly chosen according to the minimum value for the utilization of the Fischer-Tropsch reaction. The limit value is therefore preferably 60%. However, this is not mandatory. Usable results can also be achieved with a limit value set in the range of 40 to 80%, particularly in the range of 50 to 70%.
[0048] In another preferred embodiment, the process is only carried out in the second operating mode if the availability of hydrogen from electrolysis is below the specified limit.
[0049] In a further preferred embodiment of the method, in the first operating mode the component separated from the raw product in c) is divided into the first fraction and the second fraction by cooling.
[0050] In this embodiment, the second component can be separated, in particular, by liquefaction from the component separated from the crude product in c). The second component is preferably a liquefied gas. This is a substance that is gaseous under normal conditions but exists as a liquid under such conditions.
[0051] The second component can have a composition similar to liquefied petroleum gas (LPG, also known as autogas). Preferably, this second component is in liquid form after cooling, so it can be referred to as liquefied petroleum gas. However, the second component can also include substances that do not fall under the conventional definition of LPG. Therefore, the second component can also be referred to as LPG+.
[0052] In a further preferred embodiment of the method, in the second operating mode the reaction reactants in a) are partially generated from the storage substance stored in the first operating mode by reacting the storage substance at least partially by means of steam reforming.
[0053] The reaction reactants can be produced from the storage substance by means of steam reforming, for example by reacting a propane component of the storage substance with the following reaction equation:
[0054] C3W8 + 3H2O 3C0 + 7H2
[0055] This preferably takes place in the same steam reformer in which, in the first operating mode, the carbon monoxide is generated from the first fraction of the component separated from the crude product in c). The provisions regarding the provision of the steam required for steam reforming apply accordingly here as well. The storage substance is preferably at least partially fed from the storage tank into the steam reformer.
[0056] The mixture of carbon monoxide and hydrogen obtained by steam reforming is preferably fed into the Fischer-Tropsch reaction. For this purpose, this mixture can be introduced into the Fischer-Tropsch reactor.
[0057] In a further preferred embodiment of the method, in the second operating mode, the reactants in a) are partially generated from the storage substance stored in the first operating mode by reacting the storage substance at least partially by means of dry reforming. The reactants can be generated from the storage substance by means of dry reforming, for example by reacting a propane fraction of the storage substance with the following reaction equation:
[0058] C3W8 + 3CO2 -> 6CO + 4H2
[0059] This is preferably carried out in a dry reformer. The carbon dioxide required for dry reforming can be supplied to the dry reformer in various ways, for example from a carbon dioxide feed. The carbon dioxide supplied in this way can, for example, be generated from the combustion of biological material, so that the carbon dioxide supply is generally not subject to weather-related fluctuations.
[0060] The storage substance is preferably directed partly from the storage unit into the steam reformer and partly into the dry reformer.
[0061] The mixture of carbon monoxide and hydrogen obtained by dry reforming is preferably fed to the Fischer-Tropsch reaction together with the mixture of carbon monoxide and hydrogen obtained by steam reforming. Both mixtures can be introduced into the Fischer-Tropsch reactor. It is irrelevant whether the two mixtures come into contact with each other inside or outside the Fischer-Tropsch reactor.
[0062] In a further preferred embodiment of the process, the ratio of a portion of the storage substance converted by steam reforming to a portion of the storage substance converted by dry reforming is adjusted such that the reactants for the Fischer-Tropsch reactor are formed by the carbon monoxide and the hydrogen in a ratio of 1:1.5 to 2.5 to each other.
[0063] Steam reforming of propane produces carbon monoxide and hydrogen in a ratio of 3:7, as shown above. Dry reforming of propane, on the other hand, produces carbon monoxide and hydrogen in a ratio of 6:4, also shown above. The Fischer-Tropsch reaction, however, requires carbon monoxide and hydrogen in a ratio of 1:2. In the present embodiment, this ratio is ideally achieved through a suitable combination of steam and dry reforming. For example, if eight times as much propane is converted by steam reforming as by dry reforming, then 8 • 3 + 6 = 30 parts carbon monoxide are produced, and 8 • 7 + 4 = 60 parts hydrogen. This corresponds to the desired ratio of 1:2.
[0064] However, the advantages described for this embodiment cannot be achieved solely in the ideal case where carbon monoxide and hydrogen are formed in a precise 1:2 ratio. Therefore, it is intended that this ratio lies in the range of 1:1.5 to 1:2.5.
[0065] Furthermore, it can generally be assumed that the storage substance does not consist exclusively of propane. In particular, the storage substance may also contain butane. The example above serves only as an illustration. However, an analogous consideration can be made for an actual composition of the storage substance.
[0066] The division between steam reforming and dry reforming can be achieved by distributing the storage substance accordingly between the steam reformer and the dry reformer. This can be accomplished using pipelines with appropriately controlled valves.
[0067] The valves can be adjusted based on the theoretical considerations above. Alternatively, the composition of the reactants actually fed into the Fischer-Tropsch reaction can be measured and controlled by adjusting the valves.
[0068] In a further preferred embodiment of the process, at least a portion of the component of the crude product separated in c) is used to provide thermal energy for steam reforming. If the component separated from the crude product in c) is divided into a first portion and a second portion, wherein the density of the first portion is lower than the density of the second portion, this can particularly be a portion of the first portion of the component separated from the crude product in c). Steam reforming is an endothermic reaction. The steam reformer is therefore preferably heated. For this purpose, the steam reformer can be fired externally. In the present embodiment, a portion of the component of the crude product separated in c) is used for this purpose. In this respect, the described process is particularly efficient.
[0069] If dry reforming is additionally carried out, preferably at least a portion of the component of the crude product separated in c) is used to provide thermal energy for the dry reforming. If the component separated from the crude product in c) is divided into a first fraction and a second fraction, with the density of the first fraction being lower than the density of the second fraction, this can in particular be a portion of the first fraction of the component separated from the crude product in c). Providing thermal energy for the dry reforming in this way can further increase the efficiency of the process.
[0070] In another preferred embodiment of the method, a third operating mode is used.
[0071] ■ the carbon monoxide is produced in a) partly from carbon dioxide and hydrogen and partly from the component separated from the raw product in c) without storing the storage substance.
[0072] The third operating mode is similar to the first. However, unlike the first mode, no storage substance is stored in the third mode. This maximizes the yield of synthetic oil. The third operating mode can be used particularly when the storage tank is completely full. The third operating mode can be considered an alternative to the first. The process is preferably only carried out in the third operating mode if the availability of hydrogen from electrolysis is at least at the specified limit.
[0073] If the availability of hydrogen from electrolysis is at least at the specified limit, a choice can be made between the first and third operating modes. This selection can be based, for example, on the fill level of the storage tank and / or on the desired yield of synthetic oil.
[0074] The process is particularly preferred in the third operating mode, where the availability of hydrogen from electrolysis is 100%. In this case, the maximum availability of hydrogen can be used to obtain the synthetic oil with maximum yield.
[0075] Furthermore, it is preferred that the process be carried out in the third operating mode when the availability of hydrogen from electrolysis corresponds to the specified limit. In this case, the third operating mode represents a transition between the first and second operating modes. If just enough hydrogen is available at the hydrogen supply to allow the Fischer-Tropsch reaction to be carried out at minimum capacity, it is not yet necessary to draw on the storage substance to adequately feed the Fischer-Tropsch reaction. In this case, however, it may be advantageous to forgo storing the storage substance in order to avoid further reducing the already comparatively low yield of synthetic oil by diverting the storage substance.
[0076] In the third operating mode, no storage substance is stored. Therefore, in the third operating mode, the component separated from the crude product in c) is preferably not divided into a first and a second component with a density of the first component lower than that of the second component. This division is not necessary. However, since this division is generally not detrimental, it is not impossible that this division nevertheless occurs. If the second component of the component separated from the crude product in c) were to be formed in the third operating mode, it would not be stored as the storage substance.
[0077] The following table compares the three operating modes. For several example cases, the parameters explained below are given.
[0078]
[0079] The electrolyzer utilization rate, expressed as a percentage, indicates the extent to which hydrogen is produced through electrolysis. This hydrogen is supplied at the hydrogen feed point, also indicated as "hydrogen feed." It can be seen that the hydrogen feed point directly follows the electrolyzer utilization rate. The Fischer-Tropsch reactor utilization rate, expressed as a percentage, indicates the extent to which the raw product is produced via the Fischer-Tropsch reaction. The carbon dioxide feed rate, expressed as a percentage, indicates how much carbon dioxide is supplied at the carbon dioxide feed point. Since carbon dioxide is generally available in sufficient quantities, the "carbon dioxide feed rate" refers to how much carbon dioxide is drawn from the carbon dioxide feed point. The carbon dioxide feed rate to the dry reformer indicates how much carbon dioxide is fed from the carbon dioxide feed point into the dry reformer. This is only relevant for the second operating mode.The input of the storage substance indicates how much of the storage substance is introduced into the storage system during the first operating mode. Similarly, the output of the storage substance indicates how much of the storage substance is discharged from the storage system during the second operating mode. For the input of the storage substance into the storage system, it is assumed, by way of example, that in c) 10% of the crude product is separated as at least one component from the crude product. Furthermore, the yields of the crude product and the synthetic oil are given.
[0080] In the first operating mode, the availability of hydrogen from electrolysis is at least at a predefined limit. In the example considered here, this limit is 60% of the maximum hydrogen demand. The utilization of the Fischer-Tropsch reaction follows the hydrogen supply. The maximum hydrogen demand therefore corresponds to the hydrogen demand at 100% utilization of the Fischer-Tropsch reaction. If the hydrogen demand is fully met by the hydrogen supply, the hydrogen supply is, by definition, at 100%. The carbon dioxide supply also follows the hydrogen supply. The yield of the raw product is also proportional to the hydrogen availability. Since a fixed proportion of 10% of the raw product is always stored as the storage substance, the amount of the stored storage substance is also proportional to the hydrogen availability.The yield of synthetic oil is always about 10% lower than the yield of the crude product.
[0081] Since the hydrogen supply in the first operating mode, by definition, does not fall below the limit of 60% (as an example here), the utilization of the Fischer-Tropsch reaction in the first operating mode also always remains at least 60%. This allows the Fischer-Tropsch reaction to be operated continuously without having to draw on the storage substance.
[0082] In the second operating mode, the availability of hydrogen from electrolysis is below the specified limit, in this example 60%. No storage substance is added. Instead, the previously stored storage substance is used. The hydrogen supply alone is insufficient to operate the Fischer-Tropsch reaction at at least 60% capacity. However, this can be compensated for by the storage substance. Therefore, the capacity of the Fischer-Tropsch reaction in the second operating mode is always 60% – the specified minimum value for reliable continuous operation. The yield of crude product is also always 60%. Since no storage substance is added in the second operating mode, the yield of synthetic oil is also always 60%.
[0083] If no hydrogen is available from the hydrogen supply, the maximum amount of storage material is extracted. By definition, this is 100%. Conversely, if the hydrogen supply is at 40%, only one-third of the storage material needs to be extracted. The more storage material is extracted, the more carbon dioxide is fed to the dry reformer.
[0084] The third operating mode addresses the special case where the storage substance is neither stored nor withdrawn. This is demonstrated for two examples. The third operating mode can be used to maximize the yield of the synthetic oil. This is shown for the two extreme cases of 100% and 60% hydrogen availability. A hydrogen availability of 60% is an extreme case insofar as this is precisely the threshold at which the first operating mode could be used instead of the third.
[0085] In a further preferred embodiment, the method is carried out in the first operating mode or in the third operating mode if the availability of hydrogen from electrolysis is at least at a predetermined limit, and the method is carried out in the second operating mode if the availability of hydrogen from electrolysis is below the predetermined limit.
[0086] The above applies to the limit value considered here.
[0087] In another preferred embodiment of the process, the synthetic oil produced is at least partially processed into synthetic kerosene. The production of the synthetic oil and its further processing can be carried out at different locations and, in particular, by different companies. For this purpose, the synthetic oil can be transported from its production site, for example, by tanker truck to a processing plant, especially a refinery.
[0088] The synthetic oil can be processed into synthetic kerosene using conventional methods that are also used in the production of mineral kerosene.
[0089] Alternatively or in addition to further processing the synthetic oil into synthetic kerosene, it can be converted, for example, into naphtha, middle distillates and / or wax.
[0090] The invention is explained in more detail below with reference to the figure. The figure shows a particularly preferred embodiment, to which, however, the invention is not limited. The figure and the size relationships shown therein are only schematic. It shows:
[0091] Fig. 1 : an arrangement with which a process according to the invention for the production of synthetic oil can be carried out.
[0092] Fig. 1 shows an arrangement 1 with which synthetic oil 13 can be produced. The synthetic oil 13 can then be further processed, for example, into synthetic kerosene.
[0093] The arrangement 1 comprised an RWGS reactor 2, a Fischer-Tropsch reactor 3, a first separation unit 4, a second separation unit 5, a storage unit 6, a steam reformer 7 and a dry reformer 8.
[0094] A crude product 12 can be produced using the Fischer-Tropsch reactor 3. Carbon monoxide and hydrogen are supplied to the Fischer-Tropsch reactor 3 as reactants 11. A comparatively light component 14 and water 18 are separated from the resulting crude product 12 by the first separation unit 4, leaving the synthetic oil 13. The separated water 18 can be supplied to the steam reformer 7. The arrangement 1 can be operated in various modes. These differ primarily in how the reactants 11 are supplied. In a first operating mode, the component 14 separated from the crude product 12 is divided by the second separation unit 5, through cooling, into a first fraction 15 with a comparatively lower density and a second fraction 16 with a comparatively higher density.The carbon monoxide of the reactants 11 is produced partly in the RWGS reactor 2 from carbon dioxide from a carbon dioxide feed 9 and hydrogen from a hydrogen feed 10, and partly in the steam reformer 7 from the first fraction 15 of the component 14 separated from the crude product 12. The hydrogen supplied via the hydrogen feed 10 preferably originates from an electrolysis process powered by renewable energy. Furthermore, in the first operating mode, the first fraction 15 of the component 14 separated from the crude product 12 is stored in the storage tank 6 as a storage substance 17.
[0095] In a second operating mode, the reactants 11 are generated at least partially from the storage substance 17 stored in the first operating mode. This is done partly with the steam reformer 7 and partly with the dry reformer 8. The ratio of the portion of the storage substance 17 converted by steam reforming to the portion converted by dry reforming is adjusted such that the reactants 11 are formed from the carbon monoxide and hydrogen in a ratio of 1:2. In addition to the storage substance 17, carbon dioxide from the carbon dioxide supply 9 is supplied to the dry reformer 8.
[0096] In a third operating mode, the carbon monoxide from the reactants 11 is generated partly by the RWGS reactor 2 from carbon dioxide from the carbon dioxide feed 9 and hydrogen from the hydrogen feed 10, and partly by the steam reformer 7 from the component 14 separated from the crude product 12, without storing the storage substance 17. The second separation device 5 can be switched off for this purpose, so that the component 14 separated from the crude product 12 is not divided into the first fraction 15 and the second fraction 16. The corresponding line is therefore labelled with both reference numeral 14 and reference numeral 15 in Fig. 1.
[0097] Furthermore, in all operating modes, a portion of the first fraction 15 of component 14 separated from crude product 12, or a portion of component 14 separated from crude product 12, can be directly introduced into the Fischer-Tropsch reactor 3 and thus recycled. This increases the yield of the Fischer-Tropsch reaction.
[0098] Furthermore, in all operating modes, a portion of the first fraction 15 of the component 14 separated from the crude product 12, or a portion of the component 14 separated from the crude product 12, can be released from the arrangement 1 via a purge gas outlet 19. This prevents, for example, the accumulation of nitrogen in the lines of the arrangement 1.
[0099] Furthermore, in all operating modes, a portion of the first fraction 15 of component 14 separated from crude product 12, or a portion of component 14 separated from crude product 12, can be used to provide thermal energy for steam reforming in steam reformer 7. This is indicated by a dotted line. The RWGS reactor 2 is used in the first and third operating modes. In these operating modes, a portion of the first fraction 15 of component 14 separated from crude product 12, or a portion of component 14 separated from crude product 12, can be used to provide thermal energy for the reaction in RWGS reactor 2. This is also indicated by a dotted line.
[0100] When using RWGS reactor 2, wastewater 20 is also produced. Reference list
[0101] 1. Arrangement
[0102] 2 RWGS reactor
[0103] 3 Fischer-Tropsch reactor
[0104] 4 first separating device
[0105] 5 second separating device
[0106] 6 storage
[0107] 7 steam reformers
[0108] 8 dry reformers
[0109] 9 Carbon dioxide supply
[0110] 10 Hydrogen supply
[0111] 11 reaction starting materials
[0112] 12 Raw product
[0113] 13 synthetic oil
[0114] 14 separated component
[0115] 15 first share
[0116] 16 second part
[0117] 17 Storage substance
[0118] 18 Water
[0119] 19 Purge gas outlet
[0120] 20 Wastewater
Claims
Claims 1. Method for producing a synthetic oil (13), comprising: a) Providing carbon monoxide and hydrogen as reactants (11), b) Producing a crude product (12) from the reactants (11) provided in a) by means of a Fischer-Tropsch reaction, c) Separating at least one component (14) from the crude product (12) obtained in b) so that the synthetic oil (13) remains, wherein the separated component (14) has a lower density than the synthetic oil (13), wherein in a first operating mode ■ the component (14) separated from the crude product (12) in c) is divided into a first fraction (15) and a second fraction (16), wherein the density of the first fraction (15) is lower than the density of the second fraction (16), ■ the carbon monoxide is produced in a) partly from provided carbon dioxide and hydrogen and partly from the first part (15) of the component (14) separated in c) from the crude product (12), ■ the second part (16) of the component (14) separated from the crude product (12) in c) is stored as a storage substance (17), where in a second operating mode ■ the reaction reactants (11) in a) are generated at least partially from the storage substance (17) stored in the first operating mode.
2. The method according to claim 1, wherein in the first operating mode the hydrogen used for the production of the carbon monoxide is at least partially produced by electrolysis powered by renewable energies.
3. The method according to claim 2, wherein the method is only carried out in the first operating mode if the availability of hydrogen from electrolysis is at least at a predetermined limit value.
4. Method according to one of the preceding claims, wherein in the first operating mode the component (14) separated from the raw product (12) in c) is divided into the first part (15) and the second part (16) by cooling.
5. Method according to one of the preceding claims, wherein in the second operating mode the reaction reactants (11) in a) are partially generated from the storage substance (17) stored in the first operating mode by reacting the storage substance (17) at least partially by means of steam reforming.
6. Method according to claim 5, wherein in the second operating mode the reaction reactants (11) in a) are partially generated from the storage substance (17) stored in the first operating mode by reacting the storage substance (17) at least partially by means of dry reforming.
7. Method according to claim 6, wherein a ratio of a portion of the storage substance (17) converted by steam reforming to a portion of the storage substance (17) converted by dry reforming is adjusted such that the reaction reactants (11) are formed by the carbon monoxide and the hydrogen in a ratio of 1:1.5 to 2.5 to each other.
8. Method according to any one of claims 5 to 7, wherein at least a part of the component (14) of the crude product (12) separated in c) is used to provide thermal energy for steam reforming.
9. Method according to one of the preceding claims, wherein in a third operating mode ■ the carbon monoxide is produced in a) partly from provided carbon dioxide and hydrogen and partly from the component (14) separated from the crude product (12) in c) without storing the storage substance (17).
10. Method according to one of the preceding claims, wherein the produced synthetic oil (13) is at least partially further processed into a synthetic kerosene.