Process and reactor arrangement for the multistage hydrogenation of a hydrogen carrier medium

Abstract

The invention relates to a process for the multistage hydrogenation of a hydrogen carrier medium comprising the stages of catalytic initial hydrogenation of the hydrogen carrier medium in a first hydrogenation reactor (2) in first hydrogenation reaction conditions, wherein the hydrogen carrier medium has a first hydrogenation degree (HG1) when leaving the first hydrogenation reactor (2), feeding the hydrogen carrier medium from the first hydrogenation reactor (2) into a second hydrogenation reactor (3) by means of a feed (6), catalytic final hydrogenation of the hydrogen carrier medium in the second hydrogenation reactor (3) in second hydrogenation reaction conditions, wherein the hydrogen carrier medium on leaving the second hydrogenation reactor (3) has a second hydrogenation degree (HG2) which is greater than the first hydrogenation degree (HG1) when leaving the second hydrogenation reactor (3).

Description

[0001] Process and reactor arrangement for the multi-stage hydrogenation of a hydrogen carrier medium

[0002] This patent application claims priority from German patent application DE 10 2022 205 287.0, the contents of which are incorporated herein by reference.

[0003] The invention relates to a process and a reactor arrangement for the multi-stage hydrogenation of a hydrogen carrier medium.

[0004] DE 10 2020 215 444 A1 discloses a process and a plant for the material use of hydrogen.

[0005] CN 101 993 721 A discloses a process and a plant for liquid phase hydrogenation.

[0006] DE 10 2014 102 235 A1 discloses a hydrogenation reactor for hydrogenating a hydrogen carrier medium. The hydrogenation reactor is designed for a nominal load, i.e., the hydrogenation of a nominal amount of the hydrogen carrier medium with hydrogen gas. The hydrogenation reactor has a limited partial load capability, meaning it cannot easily be operated economically at a partial load, i.e., with a reduced hydrogen gas supply. In particular, the hydrogenation reactor has limited dynamics. Switching between different operating points is only possible at a reduced speed.

[0007] The invention is based on the object of improving the hydrogenation of a hydrogen carrier medium and in particular of improving the utilization of a catalyst material.

[0008] This object is achieved according to the invention by a method having the features of claim 1 and by a reactor arrangement having the features of claim 9.

[0009] The core of the invention is that the hydrogenation process is carried out in several stages, in particular at least in two stages. A hydrogen carrier medium is hydrogenated with hydrogen gas. The hydrogen gas is chemically bonded to the hydrogen carrier medium. The hydrogen gas is thereby stored. A liquid organic hydrogen carrier (LOHC) serves as the hydrogen carrier medium, in particular. Particularly advantageous hydrogen carrier media are benzyltoluene, which is hydrogenated to perhydrobenzyltoluene, dibenzyltoluene, which is hydrogenated to perhydrodibenzyltoluene, and / or toluene, which is hydrogenated to methylcyclohexane.

[0010] The hydrogen carrier medium in an initial state with an initial degree of hydrogenation is hydrogenated in a first hydrogenation reactor so that, upon leaving the first hydrogenation reactor, it has a first degree of hydrogenation that is greater than the initial degree of hydrogenation. In particular, the first degree of hydrogenation is at most 95%. The degree of hydrogenation is understood to be the proportion of the hydrogen carrier medium in the total amount of the hydrogen carrier medium that is hydrogenated. In general, the hydrogen carrier medium is a mixture of hydrogenated and unhydrogenated hydrogen carrier medium. A degree of hydrogenation of 0% means that the hydrogen carrier medium is entirely unhydrogenated, i.e., no hydrogen gas is chemically bound to the hydrogen carrier medium. A degree of hydrogenation of 100% means that the hydrogen carrier medium is completely hydrogenated, i.e., completely loaded with hydrogen gas. Further hydrogenation of the hydrogen carrier medium in this state is not possible.

[0011] A first hydrogenation step takes place in the first hydrogenation reactor, wherein the hydrogen carrier medium can, in particular, also be fed into the first hydrogenation reactor in a partially hydrogenated state. In particular, a further hydrogenation reactor can be connected upstream of the first hydrogenation reactor. The initial degree of hydrogenation with which the hydrogen carrier medium is fed into the first hydrogenation reactor is, in particular, between 0% and 50%. A so-called initial hydrogenation takes place in the first hydrogenation reactor. Initial hydrogenation reaction conditions apply to the initial hydrogenation, in particular a first hydrogenation pressure and / or a first hydrogenation temperature.

[0012] One insight of the invention is that the initial hydrogenation in the first hydrogenation reactor is deliberately incomplete, i.e., the initial degree of hydrogenation is deliberately chosen to be less than 100%. The first hydrogenation reactor, also referred to as the starter reactor, serves to hydrogenate the hydrogen carrier medium at the highest possible reaction rates. A high reaction rate results in efficient utilization of a catalyst material arranged in the first hydrogenation reactor for the catalytic hydrogenation reaction. During the initial hydrogenation in the first hydrogenation reactor, the hydrogenation temperature, in particular, is monitored. For the purposes of the invention, the hydrogenation temperature is understood to be an average temperature relative to a reaction zone of the hydrogenation reactor. In particular, the temperature is averaged over the length of a catalyst material, in particular a catalyst bed, in the reaction zone.The reaction zone is defined in particular by a reaction tube of the hydrogenation reactor. The hydrogenation temperature is an average temperature. The average temperature is understood to be an averaged temperature along the reaction length. The spatial temperature profile, in particular along the reaction length, is inhomogeneous in some regions, particularly due to the exothermic reaction, and can exhibit temperature peaks, particularly at points of highest reaction rate. Regions or points of highest reaction rate are typically located at the beginning of the reaction zone, i.e., particularly where the reactant concentration is highest. It is particularly advantageous if exothermic peaks cause comparatively small deviations in the average temperature relative to a maximum and / or minimum value of the temperature profile relative to the reaction zone, i.e., the local temperature profile.

[0013] The hydrogenation temperature is in particular in a range between 150°C and 300°C, in particular between 180°C and 270°C, and in particular between 190°C and 250°C. Temperature peaks are in particular less than 100K above the mean temperature, in particular less than 80K, and in particular less than 50K above the mean temperature.

[0014] In particular, it must be ensured that the hydrogenation temperature does not reach a predeterminable maximum value of 400°C at most, in particular 350°C at most. This protects the hydrogen carrier medium in the hydrogenation reactor. Thermal degradation of the hydrogen carrier medium is avoided and, in particular, eliminated. The formation of by-products, which can, in particular, cause contamination of the hydrogen carrier medium and, in particular, also cause contamination of any hydrogen gas released later, is thereby reduced or eliminated. In particular, this avoids the need to replace the hydrogen carrier medium due to degradation. The service life of the hydrogen carrier medium is increased. In particular, degradation products of the hydrogen carrier medium can negatively influence the service life of the catalyst material, thus shortening it.By avoiding degradation products, the service life of the catalyst material is increased. The process is economical.

[0015] The hydrogen carrier medium is fed from the first hydrogenation reactor to a second hydrogenation reactor via a feed line. The feed line is designed, for example, as a line with a pump. The feed line can also be integrated, in particular without a separate line. Alternatively or additionally, the feed line can be adjusted, in particular specifically, by means of a pressure difference between the first and second hydrogenation reactors. The first hydrogenation reactor and the second hydrogenation reactor are connected in series, i.e., one behind the other.

[0016] The second hydrogenation reactor serves for the final catalytic hydrogenation of the hydrogen carrier medium, in particular as the final, concluding hydrogenation step. It is possible for further hydrogenation reactors, in particular at least one further hydrogenation reactor, to be arranged between the first hydrogenation reactor and the second hydrogenation reactor to enable further intermediate hydrogenation stages.

[0017] The hydrogenation reaction in the second hydrogenation reactor takes place under second hydrogenation reaction conditions, i.e., in particular, at a second hydrogenation pressure and / or at a second hydrogenation temperature. In particular, the second hydrogenation reaction conditions differ from the first hydrogenation reaction conditions. In particular, the first and second hydrogenation pressures can be identical. In the second hydrogenation reactor, the hydrogen carrier medium is hydrogenated from the first degree of hydrogenation to the second degree of hydrogenation. This means that the second degree of hydrogenation is greater than the first degree of hydrogenation. A final hydrogenation takes place in the second hydrogenation reactor to provide the hydrogen carrier medium with the greatest possible degree of hydrogenation.The second degree of hydrogenation is at least 95%, in particular at least 96%, in particular at least 97%, in particular at least 98%, in particular at least 99%, in particular at least 99.5%, in particular at least 99.9%, in particular at least 99.99% and in particular at least 99.999%.

[0018] The hydrogenation reaction in the second hydrogenation reactor takes place with a second hydrogenation stroke, which corresponds to the difference between the second degree of hydrogenation and the first degree of hydrogenation. The second hydrogenation stroke is at least 5%, in particular at least 9.999%, in particular at least 25%, in particular at least 35%, and in particular at least 45%. The hydrogen content, based on the hydrogen carrier medium, in the second hydrogenation reactor is at least 0.3 wt.%, in particular at least 0.6 wt.%, in particular at least 1.5 wt.%, in particular at least 2.1 wt.%, and in particular at least 2.7 wt.%.

[0019] The first hydrogenation reactor and / or the second hydrogenation reactor are each designed, in particular, as tube bundle reactors. In particular, the first and second hydrogenation reactors are structurally identical and, in particular, identical in design. It may be advantageous, for example, to design the second hydrogenation reactor to be comparatively small, in particular smaller than the first hydrogenation reactor. In particular, the amount of catalyst material used in the second hydrogenation reactor is reduced. In particular, the final hydrogenation in the second hydrogenation reactor is unproblematic with regard to the hydrogenation temperatures. Since a comparatively low conversion occurs in the second hydrogenation reactor, the waste heat generated as a result of the exothermic reaction is comparatively small and therefore unproblematic.For example, if the first degree of hydrogenation at which the hydrogen carrier medium is fed to the second hydrogenation reactor is 80%, a maximum of 20% of the reaction enthalpy can be released as heat in the second hydrogenation reactor. It is particularly advantageous if the first degree of hydrogenation is at most 95%, in particular at most 90%, and in particular at most 80%. The proportion of maximum releasable heat increases with a lower initial degree of hydrogenation in the second hydrogenation reactor, so a higher first degree of hydrogenation is generally advantageous. This proportion of maximum releasable heat is, in particular, smaller than in the first hydrogenation reactor.

[0020] In particular, it was found that the multi-stage hydrogenation concept reduces the amount of catalyst material used compared to a prior-art single-stage hydrogenation process, in particular by at least 30%, in particular by 40%, and in particular by up to 50% or more. Furthermore, cost savings arise from the fact that the first hydrogenation reactor and the second hydrogenation reactor are, in total, smaller than a prior-art single-stage reactor with the same capacity. Due to the two-stage concept, the various hydrogenation reaction conditions, and in particular the catalyst materials used, can be specifically and differently defined in the hydrogenation reactors.

[0021] It is recognized that it is advantageous to carry out the hydrogenation process in several stages, with the reaction rate being optimized in the first stage and the conversion being optimized in the second stage.

[0022] The process and reactor arrangement are particularly suitable for the use of hydrogen gas produced from renewable energy sources, in particular from electricity generated from wind power, hydropower, and / or solar radiation, although such renewably generated electricity is naturally subject to fluctuations. These fluctuations are tolerable with the multi-stage concept according to the invention.

[0023] According to a particularly preferred embodiment, at least one additional hydrogenation unit can be used as at least a third hydrogenation reactor to hydrogenate the hydrogen carrier medium with dissolved hydrogen. This advantageous embodiment is based on the finding that the water stream contains dissolved, i.e., not chemically bound, hydrogen. Such a hydrogenation unit is also referred to as a hydrogenation cartridge, which is particularly equipped with a hydrogenation catalyst. It has been recognized that the material utilization of hydrogen can be improved or simplified and, in particular, the economic efficiency of the material utilization of hydrogen can be increased.

[0024] In the hydrogenation unit, the hydrogen carrier medium is hydrogenated with the dissolved hydrogen. A so-called post-hydrogenation takes place in the hydrogenation unit. The hydrogenation unit is arranged downstream of the first hydrogenation reactor and, in particular, of the second hydrogenation reactor.

[0025] By post-hydrogenating the hydrogen physically dissolved in the hydrogen carrier medium, the content of physically dissolved hydrogen is reduced below the solubility weight. The risk of hydrogen inadvertently outgassing from the hydrogen carrier medium at a later point in time, for example, if changed ambient conditions shift the solubility weight toward the gaseous hydrogen side, in particular due to cooling and / or pressure relief, especially in a storage container, is reduced and, in particular, eliminated. Surprisingly, it was found that by using the dissolved hydrogen to hydrogenate the hydrogen carrier medium, the effort required to remove the dissolved hydrogen is reduced and, in particular, eliminated.The efficiency of the process, particularly in the material use of hydrogen, is increased. In particular, it was also recognized that the hydrogen removed according to the prior art remains unused. Because the dissolved hydrogen is used to hydrogenate the hydrogen carrier medium, this results in increased efficiency in the material use of hydrogen. Studies have shown that the proportion of physically dissolved hydrogen, depending on the reaction conditions of the catalytic reaction, is between 0.002 wt.% and 0.005 wt.% based on the mass of the hydrogen carrier medium. The utilization of hydrogen in the material use is increased; in particular, there is a savings potential with regard to hydrogen consumption through post-hydrogenation.

[0026] Furthermore, it has been found that dissolved hydrogen in the hydrogen carrier medium can cause a malfunction of the hydrogen storage medium during operation and / or unintentional safety shutdowns of the plant. Post-hydrogenation prevents malfunctions during plant operation and increases plant safety.

[0027] In particular, several hydrogenation units, in particular arranged sequentially to one another, can be used for the material utilization of hydrogen.

[0028] A method according to claim 2 simplifies the monitoring and, in particular, maintenance of the first hydrogenation reaction conditions, in particular the first hydrogenation temperature. By recycling hydrogenated hydrogen carrier medium into the first hydrogenation reactor with the first degree of hydrogenation from the first hydrogenation reactor and / or the second degree of hydrogenation from the second hydrogenation reactor, the hydrogen carrier medium is mixed in the initial state, i.e., with the initial degree of hydrogenation. This mixture has a mixed degree of hydrogenation that is greater than the initial degree of hydrogenation. As a result, the reaction rate and the exothermicity in the first hydrogenation reactor can be specifically influenced and, in particular, optimized with regard to the reaction rate. In particular, the reaction rate and the exothermicity in the first hydrogenation reactor can be coordinated to one another in such a way that a high reaction rate is ensured while avoiding exothermic peaks.An undesirable increase in the first hydrogenation temperature, in particular of more than 400 °C, can thus be excluded.

[0029] In particular, it was found that the process enables the extraction of heat at a high temperature level, in particular by deliberately adjusting a comparatively large proportion of the recycled hydrogen carrier medium to the first hydrogenation reactor. This allows exothermic peaks in the first hydrogenation reactor to be reduced. The resulting average temperature level in the first hydrogenation reactor is comparatively high and is in particular at least 230°C, in particular at least 250°C, in particular at least 270°C, and in particular at least 300°C.

[0030] Furthermore, it was found that recycling the hydrogenated hydrogen carrier medium is also advantageous because it reduces the concentration of aromatic compounds on the catalyst material. Recycling the hydrogenated hydrogen carrier medium leads to a dilution of these aromatic compounds. Such aromatic compounds, especially more highly conjugated, planar aromatic systems, can cause undesirable deactivation phenomena due to their high adsorption affinity for the catalytically active materials. This deactivation can be reduced by recycling. Recycling the hydrogenated hydrogen carrier medium results in a higher flow velocity within the reaction tubes. This higher flow velocity is beneficial for catalyst stability, as the catalyst pores, in particular, are better and more intensively flushed.

[0031] A process according to claim 3 has proven particularly advantageous with regard to the first reaction conditions. It has been found that not only can a maximum value for the first hydrogenation temperature be advantageously influenced by changing the mixing ratio of the hydrogen carrier medium streams fed into the first hydrogenation reactor, but also that the temperature profile along the reaction tubes of the tube bundle reactor is homogenized. A mixing ratio of at least 2 can already be sufficient to achieve an advantageous temperature distribution along the tube length. A mixing ratio of at least 10 and in particular at least 100 is particularly advantageous. In particular, the mixing ratio is at most 1,000.

[0032] A process according to claim 4 or 5 enables the final hydrogenation to be carried out under advantageous second hydrogenation reaction conditions.

[0033] A process according to claim 6 promotes multi-stage, catalytic hydrogenation. The catalyst material is arranged in the first hydrogenation reactor and in the second hydrogenation reactor, in particular as a bed of catalyst particles and / or as a fixed bed. The catalyst material comprises a metal, in particular a noble metal, which is supported in particular on a catalyst support material. The catalyst support material is in particular a metal oxide, a metal hydride, a metal hydroxide and / or activated carbon. The noble metal used is in particular platinum, ruthenium, palladium, iridium, gold, silver, rhenium, rhodium, copper, nickel, cobalt, iron, manganese, chromium, molybdenum and / or vanadium. Mixed metal hydrogenation catalysts and / or bimetallic hydrogenation catalysts, which in particular comprise platinum and palladium, in particular in elemental form, have proven particularly advantageous. The catalyst support material used is in particular aluminum oxide.

[0034] It is particularly straightforward if the catalyst material used in the first and second hydrogenation reactors is identical. Handling and operation of the reactors are simplified.

[0035] Alternatively, it is possible to use a catalyst material adapted to the reaction conditions prevailing in the respective hydrogenation reactor.

[0036] A quantitative ratio in which the second mass of catalyst material in the second hydrogenation reactor amounts to at most 80% of the first mass of catalyst material in the first hydrogenation reactor has proven particularly advantageous. In particular, the ratio is at most 30% and at least 5%. A method according to claim 7 enables stable implementation of the hydrogenation reactions, in particular in the first hydrogenation reactor. By dissipating reaction heat as waste heat and transferring it to at least one thermal consumer unit, overheating of the first and / or second hydrogenation reactor is avoided. Furthermore, the reaction heat can be advantageously utilized in the at least one thermal consumer unit. The total energy requirement for the hydrogenation reactor and thermal consumer unit is reduced. A thermal consumer unit is, for example, a thermal consumer such as a heater and / or a heat storage device.A heat storage network serves as a heat storage device, in particular for storing sensible heat and / or latent heat. A thermal consumer unit can also comprise the heating of steam, in particular in an industrial park, in order to use the generated steam for energy purposes, in particular for generating electricity. A thermal consumer unit can also be an apparatus for processing the hydrogen carrier medium, in particular a distillation column and / or a similar separation apparatus for removing by-products from the hydrogen carrier medium. A hydrogenation reactor can also serve as a thermal consumer unit, in particular the first hydrogenation reactor or the second hydrogenation reactor or an additional, in particular third, hydrogenation reactor. In particular, the heat generated in one hydrogenation reactor can be dissipated into another hydrogenation reactor.

[0037] A method according to claim 8 enables an advantageous implementation of the two-stage method.

[0038] A reactor arrangement according to claim 9 essentially has the advantages of the method according to claim 1. The first and second hydrogenation reactors are arranged in series and interconnected. A feed, which in particular comprises a fluid line and in particular a pump, serves for connection.

[0039] In particular, the first and / or the second hydrogenation reactor each have a separate hydrogen gas opening to which a hydrogen gas line is connected. The hydrogen gas line can be connected to a hydrogen gas source, which can be designed, for example, as a hydrogen buffer storage container and, in particular, as an interface for introducing hydrogen gas into the hydrogen gas line. Hydrogen gas production at the hydrogenation reactor is unnecessary. Additionally or alternatively, a separate hydrogen gas source can be present to separately supply the first hydrogenation reactor and / or the second hydrogenation reactor with hydrogen gas. In particular, a separate hydrogen gas supply to the second hydrogenation reactor is possible, in particular independently of the first hydrogenation reactor.

[0040] A reactor arrangement according to claim 10 allows for spatial separation of the two reactors. The reactors are arranged separately, i.e., spatially separated from each other. Direct interactions between the series-connected reactors are essentially eliminated.

[0041] Alternatively, a reactor assembly according to claim 11 can be designed compactly in a common reactor housing. Such a reactor assembly is compact and functionally integrated.

[0042] A reactor arrangement according to claim 12 or 13 simplifies the influencing of the degree of hydrogenation of the hydrogen carrier medium to be supplied. Alternatively, it is possible to provide a separate, second source of hydrogen carrier medium to supply hydrogen carrier medium with a modified initial degree of hydrogenation to the first hydrogenation reactor, wherein the modified initial degree of hydrogenation is greater than the initial degree of hydrogenation of the hydrogen carrier medium already supplied.

[0043] A reactor arrangement according to claim 14 enables effective and immediate dissipation of reaction heat. The reactor arrangement exhibits increased overall efficiency.

[0044] A reactor arrangement according to claim 15 increases the flexibility in two-stage hydrogenation, in particular the direct influencing and, in particular, control of the first hydrogenation reaction conditions in the first hydrogenation reactor. A control unit serves, in particular, to control the mass flows of the supplied hydrogen carrier medium and the hydrogen carrier medium recirculated to the first hydrogenation reactor according to claim 3. For this purpose, the control unit is in signal communication, in particular, with the first and / or second hydrogenation reactor, in particular with sensors arranged therein, in particular temperature sensors arranged therein. The temperature signals transmitted to the control unit from the temperature sensors can be used as input signals for controlling the process.Depending on the measured temperatures, the control unit can provide control signals for the supply line and / or the return lines in order to regulate the mixing ratio of the mass flows accordingly.

[0045] A reactor arrangement according to claim 16 enables increased plant availability and / or stabilization of plant performance. Because the first hydrogenation reactor and at least one third hydrogenation reactor are arranged in parallel and interconnected, the reactors can be operated alternately to compensate for downtimes of one reactor, for example, the first hydrogenation reactor, with the other reactor, for example, the at least one third hydrogenation reactor. A reduction in plant performance can thus be avoided. The first hydrogenation reactor and the at least one third hydrogenation reactor are arranged upstream of the second hydrogenation reactor.

[0046] In particular, several third hydrogenation reactors are present, which are connected in particular in parallel to the first hydrogenation reactor.

[0047] In particular, it was recognized that in the hydrogenation reactor upstream of the second hydrogenation reactor, i.e., in the first hydrogenation reactor or in the third hydrogenation reactor, byproducts in the supplied stream of hydrogen carrier medium are deposited on the catalyst material at a high deposition rate. This comparatively high deposition rate leads to faster or earlier deactivation of the catalyst material in the first hydrogenation reactor or in the third hydrogenation reactor. Accordingly, the at least partially hydrogenated hydrogen carrier medium leaving the first hydrogenation reactor or third hydrogenation reactor has a higher quality, in particular a higher purity. The at least partially hydrogenated hydrogen carrier medium contains fewer byproducts. The catalyst material in the first hydrogenation reactor or in the third hydrogenation reactor corresponds to a combined, single-stage purification / reaction stage for the hydrogen carrier medium.

[0048] Due to the faster deactivation of the catalyst material, earlier regeneration of the catalyst material is advantageous to maintain catalyst performance. During regeneration of the catalyst material, the hydrogenation reactor cannot be used for hydrogenation or can only be used to a limited extent, i.e., at reduced capacity. For this reason, it is advantageous to have a third hydrogenation reactor connected in parallel in addition to the first hydrogenation reactor. It is also conceivable to operate both the first hydrogenation reactor and the third hydrogenation reactor simultaneously for hydrogenation of the hydrogen carrier medium, in which case the first and / or third hydrogenation reactor can be designed to be smaller.

[0049] In particular, the first hydrogenation reactor and the third hydrogenation reactor can be dimensioned such that a load range between 20% and 200%, in particular between 50% and 150%, and in particular between 80% and 120%, can be compensated. In the event of regeneration, for example, of the third hydrogenation reactor, the plant output can be stabilized, since the output of the third hydrogenation reactor, which is lost as a result of the regeneration, can be offset by the increased output of the first and second hydrogenation reactors. The interconnection enables higher partial load ranges and / or increased power dynamics overall.

[0050] Both the features specified in the patent claims and the features specified in the exemplary embodiments of reactor arrangements according to the invention are suitable, either individually or in combination with one another, for further developing the subject matter of the invention. The respective combinations of features do not represent any limitation with regard to further developments of the subject matter of the invention, but are essentially merely exemplary in nature.

[0051] Further features, advantages, and details of the invention will become apparent from the following description of exemplary embodiments with reference to the drawings. They show:

[0052] Fig. 1 is a schematic representation of a reactor arrangement according to a first embodiment with two hydrogenation reactors connected in series and arranged separately,

[0053] Fig. 2 is a representation corresponding to Fig. 1 of a reactor arrangement according to a second embodiment with a thermal consumer unit, Fig. 3 is a representation corresponding to Fig. 1 of a reactor arrangement according to a third embodiment, in which the hydrogenation reactors are arranged integrated in a common reactor housing,

[0054] Fig. 4 is a representation corresponding to Fig. 1 of a fourth embodiment with two hydrogenation reactors connected in parallel and one connected in series.

[0055] A reactor arrangement, designated as a whole by 1, comprises a first hydrogenation reactor 2 and a second hydrogenation reactor 3 connected thereto. The hydrogenation reactors 2, 3 are connected in series. This means that an outlet of the first hydrogenation reactor 2 is fluidly connected, in particular directly, to the inlet of the second hydrogenation reactor 3.

[0056] The first hydrogenation reactor 2 is referred to as the starter reactor. The second hydrogenation reactor 3 is also referred to as the finisher reactor. The reactor arrangement 1 can comprise further hydrogenation reactors, which can be arranged upstream of the first hydrogenation reactor 2, between the two hydrogenation reactors 2, 3, or downstream of the second hydrogenation reactor 3.

[0057] According to the embodiment shown, the two hydrogenation reactors 2, 3 are each designed as tube bundle reactors with several reaction tubes (not shown), which are arranged in particular parallel to one another.

[0058] The first hydrogenation reactor 2 has a first reactor housing 4 in which the reaction tubes are arranged. The second hydrogenation reactor 3 has a second reactor housing 5 in which the reaction tubes of the second hydrogenation reactor 3 are arranged. According to the illustrated embodiment, the first reactor housing 4 is larger than the second reactor housing 5, even though the schematic representation in Fig. 1 suggests a comparable or identical size.

[0059] A catalyst material (not shown in detail) is arranged in each of the reactor housings 4, 5, which can be identical in both hydrogenation reactors 2, 3. A first mass rm of the catalyst material is arranged in the first hydrogenation reactor 2. A second mass m2 of the catalyst material is arranged in the second hydrogenation reactor 3. According to the illustrated embodiment, m2 = 1 / 3 xr.

[0060] The first hydrogenation reactor 2 is connected to the second hydrogenation reactor 3 by means of a feed line 6, which, according to the exemplary embodiment shown, comprises a fluid line and a pump (not shown in detail). Instead of the pump, the feed from the first hydrogenation reactor to the second hydrogenation reactor 3 can be achieved by deliberately adjusting a pressure difference between the two reactors 2, 3. The feed line 6 connects a first discharge opening 7 of the first hydrogenation reactor 2 to a second feed opening 8 of the second hydrogenation reactor 3.

[0061] Furthermore, a first return line 9 is connected to the first discharge opening 7 and opens into a first feed opening 10 of the first hydrogenation reactor 2. A first pump 20 is arranged along the first return line 9. For this purpose, the first return line 9 can open directly into the first feed opening 10 or, as shown in Fig. 1, into a hydrogen carrier medium feed line 11. The hydrogen carrier medium feed line 11 serves to feed hydrogen carrier medium into the first hydrogenation reactor 2 at the first feed opening 10. It is possible for the first return line 9 to open directly into the hydrogen carrier medium feed line 11. Alternatively, it is possible for a mixer unit to be provided into which the first return line 9 and the hydrogen carrier medium feed line 11 open. In the mixer unit, the various hydrogen carrier media can be mixed and this mixture can then be fed to the first hydrogenation reactor 2.However, this upstream mixing in the first hydrogenation reactor 2 is not mandatory. This mixing can also take place directly in hydrogenation reactor 2.

[0062] The hydrogen carrier medium supply line 11 connects the first hydrogenation reactor 2 to a hydrogen carrier medium source 12, in particular to a storage tank. Hydrogen carrier medium with an initial degree of hydrogenation HGo between 0% and 20%, and in particular between 15% and 20%, is stored in the hydrogen carrier medium source 12. The hydrogen carrier medium source 12 can also be designed with a corresponding interface, via which hydrogen carrier medium can be supplied from a tanker vehicle and / or by means of a supply line, in particular a pipeline network. The first hydrogenation reactor 2 further has a hydrogen gas supply opening 13 through which hydrogen gas can be supplied to the first hydrogenation reactor 2. It is also possible to supply the hydrogen gas and the hydrogen carrier medium together and / or with a time delay via the first supply opening 10 to the first hydrogenation reactor 2.The separate hydrogen gas supply opening 13 would then be dispensable. A hydrogen gas line 14, which is fed from a hydrogen gas source 15, is connected to the hydrogen gas supply opening 13. A power generation unit (not shown in detail) serves as the hydrogen gas source 15, in particular for generating electrical power from renewable energy sources. The power generation unit is, for example, a photovoltaic system, a wind turbine, and / or a hydroelectric power plant. The power generation source is connected, in particular, to an electrolyzer in which water is separated into hydrogen gas and oxygen. The hydrogen gas can be fed into the hydrogen gas line 14, in particular via intermediate storage in a buffer tank (not shown).

[0063] The hydrogen gas source 15 can be designed as a corresponding interface to supply hydrogen gas into the hydrogen gas line 14, so that a separate production of hydrogen gas is not required.

[0064] The hydrogen gas source 15 is connected, in particular, via a further hydrogen gas line 14 to a corresponding hydrogen gas opening 13 in the second hydrogenation reactor 3. Additionally or alternatively, it is possible to have a separate hydrogen gas source, via which the second hydrogenation reactor 3 is exclusively supplied with hydrogen gas.

[0065] A second discharge line 17 is connected to a second discharge opening 16 of the second hydrogenation reactor 3 and serves to discharge two-stage hydrogenated hydrogen carrier medium. The second discharge line 17 opens, in particular, into a hydrogen carrier medium sink 18. The hydrogen carrier medium sink 18 is, in particular, a storage container. Additionally or alternatively, the hydrogen carrier medium sink 18 can also be a corresponding interface at which the multiply hydrogenated hydrogen carrier medium can be fed, for example, to a transport vehicle and / or into a pipeline network. Furthermore, a second return line 19 is connected to the second discharge opening 16 and is fluidly connected to the first feed opening 10 of the first hydrogenation reactor 2. According to the exemplary embodiment shown, the second return line 19 opens into the first return line 9.It is also possible for the second return line 19 to flow directly into the first hydrogenation reactor 2. A second pump 21 is arranged along the second return line 19.

[0066] It is also possible to replace the first pump 20 and the second pump 21 with a single pump, which can be arranged along the first return line 9 or the second return line 19. This single pump, in combination with valves and a suitable valve control, can enable the recirculation of hydrogen carrier medium from the first hydrogenation reactor 2 and / or the second hydrogenation reactor 3 to the first hydrogenation reactor 2.

[0067] It is also conceivable that only the first return line 9 or only the second return line 19 is present in order to return hydrogen carrier medium with a hydrogenation degree HG1 / HG2 increased compared to the initial hydrogenation degree HGo to the first hydrogenation reactor 2.

[0068] Additionally or alternatively, an additional hydrogen carrier medium container (not shown) is possible, in which hydrogen carrier medium with a hydrogenation degree increased compared to the initial hydrogenation degree HGo is stored. In this case, return lines 9, 19 are unnecessary.

[0069] The hydrogenation reactors 2, 3, the feed 6 and the return lines 9, 19 form a so-called, in particular multi-stage, hydrogenation module 24.

[0070] The reactor arrangement 1 comprises a control unit 22, which is in signal communication with the first pump 20 and the second pump 21. By means of the control unit 22, it is possible to control the pumps 20, 21 such that the mass flow of hydrogen carrier medium via the first return line 9 and the second return line 19 into the first hydrogenation reactor 2 can be specifically adjusted. The signal connection of the control unit 22 is designed, in particular, as a wired connection. However, the signal connection can also be designed wirelessly as a radio connection, as indicated in Fig. 1 by the symbol 23. The hydrogenation reactors 2, 3 are equipped with sensors (not shown in detail), which are particularly suitable for detecting the respective hydrogenation reaction conditions in the first hydrogenation reactor 2 and the second hydrogenation reactor 3. In particular, the sensors are used to measure the respective hydrogenation pressure pi, p2 and / or the respective hydrogenation temperature Ti, T2.

[0071] In particular, appropriate sensors are provided to determine the respective degree of hydrogenation HGi, HG2.

[0072] A method for operating the reactor arrangement 1 is explained in more detail below.

[0073] The process is used for the multi-stage hydrogenation of the hydrogen carrier medium. The hydrogen carrier medium is fed from the hydrogen carrier medium source 12 into the first hydrogenation reactor 2 in its initial state, i.e., with the initial degree of hydrogenation HGo. In the first hydrogenation reactor 2, a catalytic initial hydrogenation takes place, i.e., in particular, a first hydrogenation step of the hydrogen carrier medium to a first degree of hydrogenation HGI, which is, in particular, at most 95%. The hydrogenation takes place under the first hydrogenation reaction conditions, i.e., the first hydrogenation pressure pi and the first hydrogenation temperature Ti.

[0074] The hydrogen carrier medium with the first degree of hydrogenation HGi is fed from the first hydrogenation reactor 2 to the second hydrogenation reactor 3 via the feed line 6. In the second hydrogenation reactor 3, a final catalytic hydrogenation takes place to a second degree of hydrogenation HG2, which is greater than the first degree of hydrogenation HGi. The second degree of hydrogenation HG2 is in particular at least 95%.

[0075] The hydrogenation in the second hydrogenation reactor 3 takes place under second hydrogenation reaction conditions, i.e., at a second hydrogenation pressure p2 and a second hydrogenation temperature T2. The second hydrogenation pressure p2 is less than or equal to the first hydrogenation pressure pi. According to the illustrated embodiment, the first hydrogenation pressure pi is between 5 barg and 50 barg, and in particular 3 Obarg. The second hydrogenation pressure p2 is in particular 3 Obarg. The second hydrogenation temperature T2 is less than or equal to the first hydrogenation temperature Ti. According to the illustrated embodiment, Ti = 200°C to 350°C, in particular 270°C, and T2 = 200°C to 330°C, in particular 230°C.

[0076] It is essential that the first hydrogenation reaction conditions and the second hydrogenation reaction conditions can be set variably and, in particular, flexibly. In particular, it is possible for the hydrogenation reaction conditions in the first hydrogenation reactor 2 and the second hydrogenation reactor 3 to be identical and / or to be adapted, i.e., specifically changed, during the course of the hydrogenation reactions.

[0077] During the initial hydrogenation in the first hydrogenation reactor 2, a deliberately incomplete hydrogenation to the first degree of hydrogenation HGi is carried out. The initial hydrogenation should take place at the highest possible reaction rate. To avoid overheating of the first hydrogenation reactor 2, control and, in particular, regulation is possible such that the mixture of hydrogen carrier medium fed to the first hydrogenation reactor 2 via the first feed opening 10 is specifically modified. For this purpose, it is possible for hydrogen carrier medium with the first degree of hydrogenation HGi and / or with the second degree of hydrogenation HG2 to be mixed with the hydrogen carrier medium in the initial state at the initial degree of hydrogenation HGo via the first return line 9 and / or the second return line 19.In particular, the proportion of the mass flow of the hydrogen carrier medium recycled to the respective hydrogenation reactor and the hydrogen carrier medium fed to the respective hydrogenation reactor is more than 1, and in particular between 1 and 100, and in particular between 1 and 10. The mixture has an effective degree of hydrogenation HGeff that is in particular greater than the initial degree of hydrogenation HGo. Depending on the mixing ratio, the effective degree of hydrogenation HGeff is greater than the initial degree of hydrogenation HGo. This allows the reaction rate and the temperature development in the first hydrogenation reactor 2 to be coordinated and optimized.

[0078] Investigations have shown that with a mixing ratio of the mass flows of the hydrogen carrier medium returned to the first hydrogenation reactor 2 with degrees of hydrogenation HGi and / or HG2 and the hydrogen carrier medium fed into the first hydrogenation reactor 2 in the initial state starting from a value of at least 5 and in particular at least 10, a significant increase in the effective degree of hydrogenation HGeir is achieved. The effective degree of hydrogenation HGeir is in particular at least 40%, in particular at least 60%, and in particular at least 70%.

[0079] Further investigations have shown that a temperature profile along the reaction tubes in the first hydrogenation reactor 2 is essentially balanced, i.e., homogeneous, when the mixing ratio is at least 10. This, in particular, improves the stability of the hydrogen carrier medium. Degradation, especially as a result of local temperature peaks, is avoided.

[0080] In addition, higher circulation flows, due to improved heat transfer and higher flow velocities, have a positive effect on suppressing exothermic peaks. Local temperature increases can thus be avoided.

[0081] Higher flow velocities and the resulting improved heat transfer, in particular, enable reaction tubes with larger diameters. This allows hydrogenation reactors to be designed with an optimized, particularly more compact, installation space. Investment costs are reduced. Space requirements are reduced.

[0082] The final hydrogenation in the second hydrogenation reactor 3 serves, in particular, to fully convert the hydrogen carrier medium, which is fed into the second hydrogenation reactor 3 with the degree of hydrogenation HgI. No direct circulation is provided in the second hydrogenation reactor 3, i.e., the second return line 19 does not re-enter the second hydrogenation reactor 3 and / or the feed line 6. Nevertheless, hydrogen carrier medium from the second hydrogenation reactor 3 can be recirculated to the first hydrogenation reactor 2 and indirectly returned to the second hydrogenation reactor 3 via the feed line 6. In particular, hydrogen carrier medium is fed from the second hydrogenation reactor 3 exclusively via the feed line 6 into the second feed opening 8.

[0083] The input concentration, i.e., the first degree of hydrogenation HGi and thus the reaction rate in the second hydrogenation reactor 3, is not reduced due to the lack of reflux upstream of the second hydrogenation reactor 3. The first degree of hydrogenation HGi and the reaction rate in the second hydrogenation reactor 3 are comparatively high. To avoid a thermodynamic influence on the reaction equilibrium in the second hydrogenation reactor 3 and to avoid thermally overloading the hydrogen carrier medium, the second hydrogenation temperature T2 is lower than the first hydrogenation temperature Ti. Exothermic peaks, i.e., local temperature increases, can result in a comparatively heterogeneous temperature profile due to the slower flow velocity, which arises in particular due to the lack of circulating mass flow.The control of the second hydrogenation reaction conditions can be carried out without problems due to the lower residual conversion and thus lower heat development in the second hydrogenation reactor 3 and can be monitored and especially controlled by means of process thermostats.

[0084] It was found that multi-stage, particularly two-stage, hydrogenation of the hydrogen carrier medium leads to improved utilization of the catalyst material. In particular, the total catalyst material requirement, which results from the masses rm and m2, is smaller than the total mass of a comparable single-stage hydrogenation process according to the state of the art. The comparison process was based on the same target degree of hydrogenation of 98% and a hydrogen carrier medium feed rate of 189 kg / h. Calculations have shown that the catalyst requirement for the single-stage process is reduced by 40%. Furthermore, the combined sizes of the two reactors 2 and 3 are smaller than the size of a single, single-stage hydrogenation reactor. Due to the improved heat input, the diameter of the reaction tubes can be increased. The space requirement for such a hydrogenation reactor is reduced. The hydrogenation reactor is compact.

[0085] A second embodiment is described below with reference to Fig. 2. Structurally identical parts have the same reference numerals as in the first embodiment, to the description of which reference is hereby made. Structurally different but functionally similar parts are given the same reference numerals with a suffix "a."

[0086] The reactor arrangement 1a according to Fig. 2 comprises the first hydrogenation module 24, which is designed essentially identically to the first hydrogenation module 24 according to the first embodiment. The reactor arrangement 1a further comprises a second hydrogenation module 24, which is designed essentially identically to the first hydrogenation module 24.

[0087] The reactor arrangement 1a has a heat exchanger 25, with which reaction heat generated in the first hydrogenation reactor 2 can be transferred to a thermal consumer unit 26 and / or to the first hydrogenation reactor 2 of the respective other hydrogenation module 24. The heat exchanger 25 comprises, in particular, a heat transfer fluid that is heated by the heat-emitting unit, i.e., the first hydrogenation reactor 2, is transported by means of a heat transfer line, and transfers the heat to the thermal consumer unit 26 and / or the respective other first hydrogenation reactor 2. The heat flow generated thereby is referred to as Q. It is understood that a plurality of thermal consumer units can also be provided, which are connected to one another in parallel or in series. The thermal consumer units 26 can be designed as heat consumers and / or as heat storage units.The heat exchanger improves the removal of reaction heat from the first hydrogenation reactor 2. Because the waste heat from the thermal consumer unit 26 can be directly utilized and / or stored, the overall energy requirement for the reactor arrangement 1a is reduced. Additional heat sources are unnecessary or can at least be designed to be smaller.

[0088] It is advantageous if the heat exchanger 25 is in, in particular bidirectional, signal connection with the control unit 22.

[0089] A method for operating the reactor arrangement 1a is explained in more detail below.

[0090] According to a first operating mode, the individual hydrogenation modules 24 are designed for an expected minimum load so that a constant heat extraction is achieved at this minimum load level. The number of hydrogenation modules 24 depends in particular on the design of the hydrogen gas buffer storage and in particular on the width of the desired load range. If the amount of hydrogen gas temporarily stored in the hydrogen gas buffer storage falls below a specified limit, such as 15% of the buffer capacity, this can result in the hydrogenation modules 24 and, not least, the last hydrogenation module 24 still active being shut down if several hydrogenation modules 24 are operated in parallel. A hydrogen gas quantity falling below the limit can, for example, result from a long-term reduction in hydrogen production, for example from renewable energies.In this case, the hydrogenation module 24 is transferred to a so-called self-sustaining state, in which only enough hydrogen carrier medium is hydrogenated in the hydrogenation module 24 to keep the first hydrogenation temperature Ti in the first hydrogenation reactor 2 constant. This means that the exothermicity of the initial hydrogenation in the first hydrogenation reactor 2 is exactly as large as the heat losses. In self-sustaining operation, only heat losses of the first hydrogenation reactor 2 are compensated by the hydrogenation operation.

[0091] Self-sustaining operation is controlled primarily based on the hydrogenation temperature. This ensures, in particular, that the hydrogenation temperature, as an inert variable, is maintained within a range that enables a comparatively rapid and dynamic restart of hydrogenation reactor 2.

[0092] In particular, no external heat sources are required to operate the hydrogenation module 24 in self-sustaining mode.

[0093] If, in particular due to a lack of hydrogen gas supply, the self-sustaining state is not possible, i.e. no minimum hydrogenation can take place, a so-called hot standby state is possible, in which the cooling of a hydrogenation reactor 2, 3 is prevented by supplying a heat flow Q from a first external heat source.

[0094] In the reactor arrangement 1a according to Fig. 2, the first hydrogenation reactor 2 of the first hydrogenation module 24, shown on the left in Fig. 2, can serve as an external heat source for the first hydrogenation reactor 2 of the second hydrogenation module 24, shown on the right in Fig. 2. The first hydrogenation module 24 is in normal operation, and the second hydrogenation module 24 is in hot standby mode. The heat Q required for this is provided via the heat exchanger 25. The first hydrogenation reactor 2 serves as an external heat source.

[0095] It was recognized that in the hot standby state of the second hydrogenation module 24, it is not necessary to transfer external heat from the first hydrogenation module 24 to the second hydrogenation reactor 3 of the second hydrogenation module 24. As soon as the second hydrogenation module 24, in particular its first hydrogenation reactor 2, is put back into operation, the sensible heat of the hydrogen carrier medium with the first degree of hydrogenation HGi is sufficient to return the downstream second reactor 3, which is operated without circulation, to the active operating state.

[0096] In an alternative mode of operation of the reactor arrangement 1a with a reactor designed for maximum load, in particular with reactors 2, 3 designed for maximum load, the reactors 2, 3 are supplied by controlled supply of the fluid flows, in particular by means of appropriately arranged and switchable pumps, compressors, recuperators and / or control valves.

[0097] A further embodiment is described below with reference to Fig. 3. Structurally identical parts are given the same reference numerals as in the first two embodiments, to whose descriptions reference is hereby made. Structurally different but functionally similar parts are given the same reference numerals with a suffix "b."

[0098] In the reactor arrangement 1b, the first hydrogenation reactor 2b and the second hydrogenation reactor 3b are integrated in a common reactor housing 27. The reactor arrangement 1b has an integrated feed line 6b. The integrated feed line 6b is integrated, in particular, in the reactor housing 27.

[0099] The reactor housing 27 is essentially tubular and has a longitudinal axis 28, which is oriented, in particular, vertically. The longitudinal axis 28 can also be arranged at an angle of inclination relative to the vertical, wherein the angle of inclination is, in particular, less than 90°, in particular less than 60°, in particular less than 45°, in particular less than 30°, in particular less than 15°, in particular less than 5°.

[0100] The hydrogen gas line 14 and the hydrogen carrier medium supply line 11 open into an upper head region 29 of the hydrogenation module 24b. The lines 11, 14 can also be integrated and form a common inlet into the reactor 2b. Adjoining the head region 29 is a distribution device 30, which is designed, in particular, as an overflow with column trays. The distribution device 30 extends, in particular, over the entire cross-sectional area perpendicular to the longitudinal axis 28.

[0101] At least one reaction tube 31 is connected to the distributor device along the longitudinal axis 28. In particular, the first hydrogenation reactor 2b comprises a plurality of reaction tubes 31. In particular, the reaction tubes 31 are oriented parallel to one another and in particular parallel to the longitudinal axis 28.

[0102] The catalyst material is arranged, in particular, as a loose bed in the reaction tubes 21. The reaction tubes 31 open into a diversion device 32. According to the exemplary embodiment shown, the diversion device 32 is designed as a plate below a tube sheet 38 of the first hydrogenation reactor 2b. The diversion device 32 prevents hydrogen carrier medium from the reaction tubes 31 of the first hydrogenation reactor 2b from passing directly into the reaction tubes 31 of the second hydrogenation reactor 3b. The diversion device 32 diverts the fluid flow of the hydrogen carrier medium from the first hydrogenation reactor 2b into the second hydrogenation reactor 3b.

[0103] Additionally or alternatively, the fluid flow from the first hydrogenation reactor 2b into the second hydrogenation reactor 3b can be influenced by arranging the reaction tubes 31 of the first hydrogenation reactor 2b and the second hydrogenation reactor 3b out of alignment with one another. Hydrogen carrier medium dripping and / or flowing from the reaction tubes 31 of the first hydrogenation reactor 2b reaches a space between the reaction tubes 31 of the second hydrogenation reactor 3b. In this case, the flow is redirected without a physical, i.e., physical, redirection device. In this case, a separate recycle stream with a defined volume from the sump 33 can be enabled.

[0104] Additionally or alternatively, the diversion device 32 can be integrated into the distribution device. This makes it possible, in particular, to avoid overflow from a direct feed from the first hydrogenation reactor 2b. Such an integrated solution corresponds to a bubble-cap tray of a column with a roof. From the diversion device 32, the hydrogen carrier medium partially hydrogenated in the first hydrogenation reactor 2b is discharged into a sump 33. The sump 33 is defined as the space between a base plate of the diversion device 32 of the first hydrogenation reactor 2b and the distribution device 30 of the second hydrogenation reactor 3b in the axial direction relative to the longitudinal axis 28.

[0105] An exact geometric separation of the first hydrogenation reactor 2b and the second hydrogenation reactor 3b is not provided in the reactor arrangement 1b. In particular, there is a smooth transition from the bottom 33 of the first hydrogenation reactor 1b to the head region 29 of the second hydrogenation reactor 3b. A virtual separation provided for this purpose is indicated by the dashed line 34 shown in Fig. 3 purely for illustrative purposes. The line 34 symbolizes a conceptual dividing plane between the first hydrogenation reactor 2b and the second hydrogenation reactor 3b.

[0106] A cooling unit 35 is integrated into the first hydrogenation reactor 2b. The cooling unit 35 is designed, in particular, as a thermal oil system or as a saturated steam circuit. The cooling unit 35 has an inlet line 36 and an outlet line 37 for supplying and removing cooling medium from the integrated cooling unit 35. A thermostat can be arranged outside the first hydrogenation reactor 2b, in particular along the inlet line 36 and / or along the outlet line 37. According to the exemplary embodiment shown, the effective flow direction of the cooling medium is opposite to the flow direction of the hydrogen carrier medium in the reaction tubes 31. The cooling unit 35 is operated in a countercurrent process. It is understood that other operating modes are also conceivable, in particular cocurrent operation.

[0107] The cooling medium flows around the reaction tubes 31, in particular on their outer sides, i.e., the spaces formed by the reaction tubes 31. The first return line 9 connects the sump 33 of the first hydrogenation reactor 2b with the head region 29 of the first hydrogenation reactor 2b. This allows the at least partially hydrogenated hydrogen carrier medium to be returned to the head region of the first hydrogenation reactor 2b. According to the illustrated embodiment, the first return line 9 is routed within the first hydrogenation reactor 2b, i.e., within the common reactor housing 27. This results in energy optimization potential, which, in particular, minimizes heat losses.

[0108] The first pump, not shown in Fig. 3, which is required for the return of the hydrogen carrier medium, is arranged in particular outside the housing 27. For this purpose, the first pump can be arranged on a section of the first return line 9 that is arranged outside the first hydrogenation reactor 2b and in particular outside the housing 27. In particular, the first pump is arranged on a section of the first return line 9 that protrudes on an upper end face of the housing 27.

[0109] Alternatively, the first return line 9 can be arranged, in particular, substantially entirely outside the housing 27. For example, an opening can be provided in an outer circumferential surface of the housing 27, to which the first return line 9 is connected and opens into the first hydrogenation reactor 2b at an upper side, in particular in the head region 29 and in particular at the upper end face of the housing 27. Alternatively, the return line can also open into the hydrogen gas line 14 and / or the hydrogen carrier medium supply line 11.

[0110] The second hydrogenation reactor 3b is essentially identical to the first hydrogenation reactor 2b, which is why further explanation is omitted.

[0111] Since the distribution device 30 of the second hydrogenation reactor 3b is also designed as an overflow, this must be arranged above the first return line 9 in the sump 33 of the first hydrogenation reactor 2b in order to improve and, in particular, to ensure continuous return of the hydrogen carrier medium. Due to the particularly constant metering of the hydrogen carrier medium into the first hydrogenation reactor 2b, the fill level in the sump 33 rises continuously with a constant return flow, which results in continuous feeding of the reaction tubes 31 in the second hydrogenation reactor 3b. The reactor arrangement 1b can have a second return line from the sump 33 of the second stage into the head region 29 of the first hydrogenation reactor 2b.

[0112] The reaction tubes 31 of the first and second hydrogenation reactors 2b, 3b are directly connected to each other on the gas side, eliminating the need for a separate hydrogen gas supply for the second hydrogenation reactor 3b. Alternatively, an additional hydrogen gas line can be provided at the head region 29 of the second hydrogenation reactor 3b.

[0113] A diversion device (not shown) can be arranged in the sump 33 of the first hydrogenation reactor 2b in order to prevent the hydrogen carrier medium hydrogenated in the first hydrogenation reactor 2b from being released directly into the second hydrogenation reactor 3b.

[0114] The diversion device diverts the hydrogen carrier medium flowing from the reaction tubes 31 of the first hydrogenation reactor 2b. This promotes the return of the hydrogen carrier medium. This has the advantage that the arrangement of the reaction tubes 31 in the first hydrogenation reactor 2b and in the second hydrogenation reactor 3b can be identical, in particular without any geometric offset from one another. This ensures a space-optimized design. A further distribution device, in particular analogous to the column trays, is particularly suitable as a diversion device, wherein the overflow is either arranged offset from the reaction tubes 31 of the second hydrogenation reactor 3b or is arranged at the outer edge of the reactor housing 27, so that the hydrogen carrier medium hydrogenated in the first hydrogenation reactor 2b can flow from the reaction tubes 31 of the first hydrogenation reactor 2b into the sump 33 at this outer edge.

[0115] A further exemplary embodiment is described below with reference to Fig. 4. Structurally identical parts are given the same reference numerals as in the previous exemplary embodiments, to whose description reference is hereby made. Structurally different but functionally similar parts are given the same reference numerals followed by a c. The reactor arrangement 1c essentially corresponds to that of the first exemplary embodiment, with the additional provision of a third hydrogenation reactor 38. The third hydrogenation reactor 38 is arranged parallel to the first hydrogenation reactor 2 and is connected to the hydrogen carrier medium supply line 11 and to the hydrogen gas line 14 by means of corresponding branch lines. Accordingly, a third discharge opening 39 is provided, which is connected to both the supply line 6 and the first return line 9. It is also conceivable to provide a separate return line for the third hydrogenation reactor 38.Several third hydrogenation reactors 38 may also be present and in particular arranged parallel to the first hydrogenation reactor 2.

[0116] The reactor arrangement 1c enables more flexible operation, in particular alternating or simultaneous operation of the first hydrogenation reactor 2 and the third hydrogenation reactor 38. It has been recognized that, due to a high deposition rate of byproducts, the hydrogenation catalyst in the first hydrogenation reactor 2 and / or in the third hydrogenation reactor 38 must be regenerated. To avoid downtimes due to the regeneration of the first hydrogenation reactor 2 or the third hydrogenation reactor 38, the other hydrogenation reactor, i.e., the third hydrogenation reactor 38 or the first hydrogenation reactor 2, serves as a redundant hydrogenation reactor.

Claims

Patent claims 1. A process for the multi-stage hydrogenation of a hydrogen carrier medium comprising the process steps of catalytic initial hydrogenation of the hydrogen carrier medium in a first hydrogenation reactor (2; 2b) under first hydrogenation reaction conditions, wherein the hydrogen carrier medium has a first degree of hydrogenation (HGi) upon leaving the first hydrogenation reactor (2; 2b), Feeding the hydrogen carrier medium from the first hydrogenation reactor (2; 2b) into a second hydrogenation reactor (3; 3b) by means of a feeder (6; 6b), catalytic final hydrogenation of the hydrogen carrier medium in the second hydrogenation reactor (3; 3b) under second hydrogenation reaction conditions, wherein the hydrogen carrier medium upon leaving the second hydrogenation reactor (3; 3b) has a second degree of hydrogenation (HG2) which is greater than the first degree of hydrogenation (HGi).

2. Method according to claim 1, characterized by recycling hydrogenated hydrogen carrier medium from the first hydrogenation reactor (2; 2b) and / or from the second hydrogenation reactor (3; 3b) into the first hydrogenation reactor (2; 2b).

3. Method according to claim 2, characterized in that the mixing ratio of the mass flows of the hydrogen carrier medium recycled to the first hydrogenation reactor (2; 2b) and the hydrogen carrier medium supplied to the first hydrogenation reactor (2; 2b) is more than 1, in particular at least 2, in particular at least 5, in particular at least 10, in particular at least 25 and in particular at least 100.

4. Method according to one of the preceding claims, characterized in that a second hydrogenation pressure (P2) is less than or equal to a first hydrogenation pressure (pi).

5. Method according to one of the preceding claims, characterized in that a second hydrogenation temperature (T2) is less than or equal to a first hydrogenation temperature (Ti).

6. A method according to one of the preceding claims, characterized by using a catalyst material which is identical in particular in both hydrogenation reactors (2, 3; 2b; 3b), wherein a second mass (m2) of the catalyst material in the second hydrogenation reactor (3; 3b) is smaller than a first mass (r) of the catalyst material in the first hydrogenation reactor (2; 2b), wherein in particular: m2 < 0.8 • mi, in particular m2 < 0.7 • mi, in particular m2 < 0.5 • r and in particular m2 < 0.3 • mi.

7. Method according to one of the preceding claims, characterized by transferring reaction heat from the first hydrogenation reactor (2; 2b) and / or from the second hydrogenation reactor (3; 3b) to at least one thermal consumer unit (2, 26).

8. Method according to one of the preceding claims, characterized in that 50% < HGi < 95% applies, in particular 60% < HGi < 90% and in particular 70% < HGi < 90%.

9. Reactor arrangement for multi-stage hydrogenation of a hydrogen carrier medium with a first hydrogenation reactor (2; 2b) for the catalytic initial hydrogenation of the hydrogen carrier medium, a second hydrogenation reactor (3; 3b) connected to the first hydrogenation reactor (2; 2b) by means of a feeder (6; 6b) for supplying the hydrogen carrier medium, for the catalytic final hydrogenation of the hydrogen carrier medium.

10. Reactor arrangement according to claim 9, characterized in that the first hydrogenation reactor (2) has a first reactor housing (4) and the second hydrogenation reactor (3) has a second reactor housing (5).

11. Reactor arrangement according to claim 9, characterized in that the first hydrogenation reactor (2b) and the second hydrogenation reactor (3b) are integrated in a common reactor housing (27).

12. Reactor arrangement according to one of claims 9 to 11, characterized by a first return line (9) which connects a first discharge opening (7) of the first hydrogenation reactor (2; 2b) with a first feed opening (10) of the first hydrogenation reactor (2; 2b). Reactor arrangement according to any one of claims 9 to 12, characterized by a second return line (19) connecting a second discharge port (16) of the second hydrogenation reactor (3; 3b) to a first feed port (10) of the first hydrogenation reactor (2; 2b). Reactor arrangement according to any one of claims 9 to 13, characterized by a heat exchanger (25) for transferring reaction heat from the first hydrogenation reactor (2; 2b) and / or from the second hydrogenation reactor (3; 3b) to at least one thermal consumer unit (2, 26).Reactor arrangement according to any one of claims 9 to 14, characterized by a control unit (22) for controlling the mixing ratio of the mass flows of the hydrogen carrier medium recycled to the first hydrogenation reactor (2; 2b) and the hydrogen carrier medium supplied to the first hydrogenation reactor (2; 2b), wherein the control unit (22) is in signal communication with at least one pump (20, 21) arranged along a return line (9, 19). Reactor arrangement according to any one of claims 9 to 15, characterized by at least one third hydrogenation reactor (38) connected in parallel to the first hydrogenation reactor (2; 2b).

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