Process and reactor assembly for the hydrogenation of a carrier medium for hydrogen

Abstract

A process for hydrogenating a carrier medium for hydrogen comprises the process steps of catalytically hydrogenating the carrier medium for hydrogen in a hydrogenation reactor (2, 3) and specifically removing the waste heat generated during hydrogenation from the hydrogenation rector (2, 3) to at least one heat absorbing unit (2, 3, 5, 17) by means of a heat exchanger (4).

Description

[0001] Process and reactor arrangement for hydrogenating a hydrogen carrier medium

[0002] This patent application claims priority from German patent application DE 10 2022 205 291.9, the contents of which are incorporated herein by reference.

[0003] The invention relates to a method and a reactor arrangement for hydrogenating a hydrogen carrier medium.

[0004] DE 10 2014 102 235 A1 discloses a hydrogenation reactor for hydrogenating a hydrogen carrier medium. The catalytic hydrogenation reaction is exothermic. Complex measures are required to prevent overheating of the hydrogenation reactor.

[0005] DE 10 2021 203 885 A1 discloses a method and a system for providing hydrogen gas.

[0006] DE 10 2015 219 306 A1 discloses a reactor device for loading and / or unloading a carrier medium with or from hydrogen and a plant with such a reactor device.

[0007] The invention is based on the object of improving the heat management during the hydrogenation of a hydrogen carrier medium.

[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 12.

[0009] The core of the invention is that waste heat generated during the catalytic hydrogenation of hydrogen carrier medium in a hydrogenation reactor is specifically dissipated to at least one heat absorption unit. The waste heat can also be dissipated to several heat absorption units, which are arranged in particular in parallel and / or in series. A heat absorption unit can be a heat consumer and / or a heat storage unit. A heat exchanger is used, in particular, to dissipate the waste heat resulting from the exothermic reaction in the hydrogenation reactor. It has been recognized that the process according to the invention, on the one hand, relieves the thermal load on the hydrogenation reactor. The effort required to cool the hydrogenation reactor, in particular the expenditure on equipment and / or process engineering, is reduced. In particular, complex cooling measures, in particular cooling elements, can be reduced and are in particular dispensed with.On the other hand, the heat that is already generated can be used in a targeted manner, reducing overall energy consumption. Such a process is both economically and ecologically valuable.

[0010] For example, the removed waste heat can be used to purify the hydrogen carrier medium in a purification unit. Such a purification step may be necessary, especially at regular intervals and particularly through distillative purification, if the hydrogen carrier medium contains impurities, particularly degradation products, particularly as a result of thermal overload. Another possible use of waste heat is, for example, the desalination of seawater to prepare water for electrolysis, particularly for the production of hydrogen gas.

[0011] The process according to the invention enables improved heat management and synergistically combines the advantages of targeted heat removal from the hydrogenation reactor on the one hand and the advantageous utilization of waste heat in the at least one heat absorption unit on the other. In particular, this makes it possible to use the waste heat to activate, in particular reactivate, additional hydrogenation reactors in order to adjust the overall storage capacity of such a reactor arrangement in a targeted and, in particular, flexibly variable manner.

[0012] In catalytic hydrogenation, the hydrogen carrier medium is hydrogenated with hydrogen gas. The hydrogen gas is chemically bound to the hydrogen carrier medium. The hydrogen gas is thereby stored. A liquid organic hydrogen carrier (LOHC) is used as the hydrogen carrier medium. Particularly advantageous hydrogen carrier media are benzyltoluene, which is hydrogenated to perhydrobenzyltoluene, dibenzyltoluene, which is hydrogenated to perhydrobenzyltoluene, and / or toluene, which is hydrogenated to methylcyclohexane. The hydrogen carrier medium is hydrogenated in the hydrogenation reactor starting from an initial state with an initial degree of hydrogenation. Upon leaving the hydrogenation reactor, the hydrogen carrier medium has a first degree of hydrogenation that is greater than the initial degree of hydrogenation.In particular, the first degree of hydrogenation is at least 95%, 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%.

[0013] Hydrogenation can be carried out in one or more stages. If the hydrogenation is carried out in several stages, the hydrogen carrier medium is initially hydrogenated in a first hydrogenation reactor and dehydrogenated in at least one second hydrogenation reactor connected in series.

[0014] It has been recognized that multi-stage hydrogenation allows the catalyst material to be used efficiently and, in particular, reduces the total requirement for catalyst material relative to the amount of hydrogen gas stored. In multi-stage hydrogenation, the hydrogen carrier medium is deliberately incompletely hydrogenated during the initial hydrogenation, in particular to a first degree of hydrogenation of at most 95%. The first hydrogenation reactor is also referred to as the starter reactor and serves, in particular, to enable the highest possible reaction rates. In the second hydrogenation reactor, the hydrogen carrier medium is dehydrogenated, in particular to a second degree of hydrogenation of 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%.

[0015] According to the invention, it was recognized that the use of hydrogen gas produced from renewable energy sources, especially from electricity generated from wind power, hydropower, and / or solar radiation, is particularly improved. In particular, the process enables flexible adjustment of reactor power to fluctuating hydrogen quantities. Electricity generated from such renewable sources is naturally subject to fluctuations. These fluctuations are tolerable with the inventive concept.

[0016] A method according to claim 2 reduces the risk of an undesired interruption in the hydrogen gas supply to the hydrogenation reactor. A method according to claim 3 makes it possible to connect several hydrogenation reactors in parallel in such a way that increased plant availability and / or stabilization of the plant performance, i.e., the hydrogen storage capacity, is ensured. In particular, at least two and in particular more than two hydrogenation reactors can be connected in parallel. The hydrogenation reactors can be operated either in a hydrogenation mode or in a regeneration mode. In particular, the various operating modes for the hydrogenation reactors can be individually defined. In particular, an operation in which all hydrogenation reactors are operated in hydrogenation mode is possible.It is also possible to operate at least one hydrogenation reactor in hydrogenation mode and at least one further hydrogenation reactor in regeneration mode and, in particular, several hydrogenation reactors in regeneration mode.

[0017] It has been recognized that byproducts in the supplied hydrogen carrier medium can deposit on the hydrogenation catalyst. These deposits deactivate the hydrogenation catalyst, which can be reactivated using a regeneration process in regeneration mode. During regeneration, the hydrogenation reactor is not usable for the hydrogenation process, or at best only to a limited extent. By connecting several hydrogenation reactors in parallel, hydrogenation operation is ensured in at least one hydrogenation reactor while at least one hydrogenation reactor is in regeneration mode. In particular, the hydrogenation reactors connected in parallel can be dimensioned such that their load range is between 20% and 200%, in particular between 50% and 150%, and in particular between 80% and 120%. By connecting the hydrogenation reactors in parallel, higher partial load ranges overall and, in particular, increased plant dynamics can be realized.

[0018] In particular, it was recognized that, depending on the regeneration process, heat is added or removed in the at least one parallel hydrogenation reactor. The parallel hydrogenation reactor in regeneration mode can be used particularly advantageously for heat absorption. In particular, the waste heat generated during hydrogenation can be transferred from the hydrogenation reactor to the parallel hydrogenation reactor in regeneration mode. If the parallel hydrogenation reactor is operated with a regeneration process in which heat is removed from the reactor, this parallel hydrogenation reactor can advantageously dissipate the heat specifically to the at least one heat absorption unit. The fact that the at least one heat absorption unit is already present enables particularly efficient and inexpensive heat removal.

[0019] In particular, it was found that a combined, single-stage purification and / or hydrogenation reaction of LOHC takes place in the hydrogenation reactors. Due to the increased removal rate of byproducts on the hydrogenation catalyst, the at least partially hydrogenated hydrogen carrier medium exhibits higher quality, in particular, higher purity with fewer impurities.

[0020] If the hydrogenation is carried out in multiple stages, it is advantageous to have several hydrogenation reactors as starter reactors for the initial hydrogenation. The starter reactors can be connected in parallel to increase plant availability and / or stabilize plant performance, enabling regular regeneration of the hydrogenation catalyst.

[0021] In a process according to claim 4, a parallel hydrogenation reactor is used as the heat absorption unit. The parallel hydrogenation reactor is connected, in particular, in parallel with the hydrogenation reactor. Material flows, in particular of the hydrogen carrier medium and / or the hydrogen gas, are separated from each other for the two reactors, and in particular the hydrogen carrier medium is not exchanged between the two hydrogenation reactors. The hydrogenation reactors are operated separately and, in particular, independently of each other. Nevertheless, the waste heat from the hydrogenation reactor can be transferred to the parallel hydrogenation reactor and utilized there.

[0022] A method according to claim 5 enables the operation of the hydrogenation reactor and / or the at least one parallel hydrogenation reactor in a so-called self-sustaining mode. The hydrogenation reactors are operated with a neutral heat balance, so that just enough hydrogen carrier medium is hydrogenated in the respective hydrogenation reactor so that the heat generated as a result of the exothermic hydrogenation reaction is sufficient to maintain the temperature in the hydrogenation reactor. The exothermicity of the reaction thus serves to compensate for heat losses that can occur, for example, due to waste heat from the reactor arrangement. In particular, such heat losses are relatively low and amount in particular to a maximum of 10% based on the heat output of the hydrogenation reaction, in particular to a maximum of 5%, in particular to a maximum of 3%, and in particular to a maximum of 1%.

[0023] In particular, heat demand and heat consumption in the hydrogenation reactors are monitored, especially continuously. In particular, a control and / or regulation system is provided such that the heat generation resulting from the exothermic nature of the hydrogenation reaction is monitored and adjusted to a heat demand, especially a forecast one.

[0024] A method according to claim 6 enables flexible and, in particular, dynamic adjustment of the hydrogen output to the amount of hydrogen gas available. In particular, the operation of the self-sustaining mode is thereby simplified and, in particular, improved.

[0025] A method according to claim 7 enables additional flexibility with regard to operating modes. An external heat source is used to maintain a required temperature level in the hydrogenation reactor and / or the at least one parallel hydrogenation reactor, particularly in the event that insufficient or no hydrogen gas is available, for example, to operate the hydrogenation reactors in self-sustaining mode. The method ensures that the hydrogenation reactor does not cool down undesirably. Reactivation time is thereby shortened.

[0026] The temperature level at which the hydrogenation reactor and / or the parallel hydrogenation reactor are maintained in hot standby operation is particularly relevant for dynamic connection and / or dynamic shutdown of the reactor arrangement. This temperature level is at least 100°C, in particular at least 150°C, and in particular at least 180°C. Hot standby operation lasts at least 10 minutes, in particular at least 30 minutes, in particular at least one hour, in particular several hours, and can in particular continue continuously, virtually indefinitely. For economic reasons, it is expedient if hot standby operation does not last too long, in particular at most 48 hours, in particular 24 hours, and in particular at most 12 hours. A method according to claim 8 enables advantageous operation of the reactor arrangement.It is not only possible to place the hydrogenation reactor and / or the parallel hydrogenation reactor into hot standby mode and / or self-sustaining mode, but also, in particular, to return these reactors to a power operating point. The power operating point is within a power range that corresponds to the nominal power range of the hydrogenation reactors and, in particular, is at least 50% of the nominal power. In particular, the switching or switching back from hot standby mode and / or self-sustaining mode to the power operating point can be carried out dynamically.

[0027] It has been recognized that it is advantageous if the temperature level and / or the pressure level in the hydrogenation reactors and / or parallel hydrogenation reactors are maintained at a minimum level during hot standby operation and / or self-sustaining operation. A minimum temperature is, in particular, at most 50 K, in particular, at most 30 K, in particular, at most 20 K, and in particular, at most 10 K below the temperature at the power operating point. A minimum pressure level is, in particular, at most 1 bar, in particular, at most 0.5 bar, in particular, at most 0.2 bar, and in particular, at most 0.1 bar below the pressure level at the power operating point.

[0028] Dynamic power control is also possible, or alternatively, by switching on and / or off individual hydrogenation reactors and / or parallel hydrogenation reactors. This takes into account the fluctuating hydrogen release from renewable energy sources. In particular, the modular switching on and off of the hydrogenation reactors and / or parallel hydrogenation reactors allows the respective operating mode to be determined on a module-by-module basis. This makes it possible to reduce the size of hydrogen buffer storage for individual modules or to dispense with it altogether.

[0029] A method according to claim 9 enables targeted and particularly flexible control of various hydrogenation reactors and / or their heat supply. This allows reactor arrangements with multiple hydrogenation reactors to be made accessible to flexible operation, in particular through flexible, particularly time-dependent, connection and disconnection of various reactors. A method according to claim 10 is particularly energy-efficient, since the energy consumption for an external heat source as an additional component is reduced and, in particular, eliminated. In particular, the already existing hydrogenation reactor serves as an external heat source for the at least one parallel hydrogenation reactor.

[0030] A method according to claim 11 enables further uses, in particular the deferred use of waste heat from the hydrogenation reactor. For this purpose, at least one heat storage unit is coupled to the heat exchanger as a heat absorption unit. The waste heat from the hydrogenation reactor can be stored in the heat storage unit and released again at a later time.

[0031] It is understood that in a reactor arrangement at least one heat storage device and / or at least one heat consumer can be combined and in particular flexibly interconnected, in particular connected to the heat exchanger.

[0032] A reactor arrangement according to claim 12 essentially has the advantages of the method according to claim 1, to which reference is hereby made. The at least one heat absorption unit serves to absorb heat, i.e., to store and / or consume heat. Consumption in this context means that heat is converted into other forms of energy. It is essential that the heat exchanger thermally couples the hydrogenation reactor and the at least one heat absorption unit, i.e., is suitable for transferring the waste heat from the hydrogenation reactor to the at least one heat absorption unit. A heat exchanger, which uses a fluid, in particular a liquid, in particular thermal oil and / or a gas or vapor, in particular steam, as the heat transfer medium, with which heat is transferred from one process to another, serves in particular as a heat exchanger.Additionally or alternatively, the heat can be transferred directly to the fluid of the heat absorption unit to be coupled using the heat exchanger, in particular by heating water for a desalination plant.

[0033] A reactor arrangement according to claim 13 enables the compensation of fluctuations in the hydrogen gas supply. A parallel hydrogenation reactor according to claim 14 enables different operating modes, particularly under different load conditions of the reactors.

[0034] A control unit according to claim 15 expands the possibilities for automated operation of the reactor arrangement, in particular depending on the available hydrogen gas supply and / or the current operating load and / or the respective reactor temperature. For this purpose, the control unit is in signal communication, in particular with the hydrogenation reactor, the at least one parallel hydrogenation reactor, in particular with at least one further heat absorption unit, in particular with the heat exchanger, in particular with the hydrogen buffer storage, and in particular with control elements such as pumps and / or valves, in order to enable and / or influence variable fluid flows in the reactor arrangement.

[0035] An external heat source according to claim 16 enables the so-called standby operation for the hydrogenation reactor and / or the parallel hydrogenation reactor.

[0036] A heat storage device according to claim 17 serves for delayed heat utilization. Particularly during maximum load operation, heat can be advantageously buffered in the at least one heat storage device. This heat can be used at a later time, for example, for maintenance in hot standby operation in a low-load state and / or in a self-sustaining state.

[0037] 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.

[0038] Further features, advantages, and details of the invention will become apparent from the following description of exemplary embodiments with reference to the drawings. In the drawings: Fig. 1 shows a schematic representation of a reactor arrangement according to a first exemplary embodiment with two hydrogenation reactors connected in parallel and a heat absorption unit,

[0039] Fig. 2 is a representation corresponding to Fig. 1 of a reactor arrangement according to a second embodiment, in which the hydrogenation reactors are designed as hydrogenation modules, each with two hydrogenation reactors connected in series.

[0040] A reactor arrangement, designated as a whole by 1, comprises a first hydrogenation reactor 2, shown on the left in Fig. 1, and a second hydrogenation reactor 3, shown on the right in Fig. 1. The two hydrogenation reactors 2, 3 are interconnected by means of a heat exchanger 4. According to the exemplary embodiment shown, heat is transferred from the first hydrogenation reactor 2 to the second hydrogenation reactor 3 as heat flow Q. The heat exchanger 4 comprises a heat transfer line with which a heat transfer fluid, in particular thermal oil, can be conveyed.Alternatively, the hydrogenation reactors 2, 3 can be operated without heat exchangers with a single thermal oil system, in particular if one of the hydrogenation reactors 2, 3 is in standby mode, i.e. does not release heat into the thermal oil circuit, but consumes heat that has been released into the thermal oil circuit by the other hydrogenation reactor to compensate for heat losses.

[0041] Since the second hydrogenation reactor 3 is arranged parallel to the first hydrogenation reactor 2, the second hydrogenation reactor 3 is also referred to as a parallel hydrogenation reactor.

[0042] Since the parallel hydrogenation reactor 3 receives heat from the first hydrogenation reactor 2, the parallel hydrogenation reactor 3 forms a heat absorption unit.

[0043] A further heat absorption unit 5 is connected along the heat exchanger line, which can be designed as a heat consumer and / or as a heat storage unit. It is understood that further heat absorption units can be connected to the heat exchanger line. In particular, the heat exchanger 4 enables bidirectional heat transfer. Depending on the operating mode of the reactor arrangement, it is conceivable, for example, that heat is transferred from the second hydrogenation reactor 3 to the first hydrogenation reactor 2. It is also conceivable that both hydrogenation reactors 2, 3 feed heat into the heat exchanger 4, wherein this heat can be transferred to the at least one heat absorption unit 5 and stored and / or consumed there.

[0044] The hydrogenation reactors 2, 3 are, in particular, identical in design and, in particular, each have a reactor housing (not shown in detail). The two hydrogenation reactors 2, 3 are, in particular, each designed as a tube bundle reactor with a plurality of reaction tubes (not shown in detail), which are arranged, in particular, parallel to one another.

[0045] In the hydrogenation reactors 2, 3, catalyst material is arranged, which is contacted by the hydrogen carrier medium in order to chemically bind hydrogen gas to the hydrogen carrier medium and thereby store it.

[0046] The heat exchanger 4 may additionally comprise a heat pump (not shown in detail), in particular to adapt the temperature level of the waste heat from the hydrogenation reactors 2, 3 to the temperature level of the at least one heat absorption unit 5. Additionally or alternatively, it is also possible to make the waste heat from the hydrogenation reactors 2, 3 available for cooling by means of a thermally operated refrigeration machine.

[0047] A heat absorption unit 5 within the meaning of the invention is also a local and / or district heating network, which can be used in particular to smooth heat profiles of the hydrogenation reactors 2, 3 depending on the hydrogen storage capacity.

[0048] A hydrogen carrier medium source 6 is connected upstream of each of the two hydrogenation reactors 2, 3, which is connected to the hydrogenation reactors 2, 3 via a hydrogen carrier medium supply line 7. The hydrogen carrier medium source 6 is designed, in particular, as a storage container in which the hydrogen carrier medium with an initial hydrogenation degree of HGo is stored. According to the illustrated embodiment, a common hydrogen carrier medium source 6 is provided for both hydrogenation reactors 2, 3. It is also possible to connect a separate hydrogen carrier medium source 6 to each hydrogenation reactor 2, 3.

[0049] The hydrogen carrier medium source 6 can alternatively be designed as an interface via which hydrogen carrier medium can be supplied and in particular made available from a tank vehicle and / or by means of a supply line, in particular a line network.

[0050] Each of the hydrogenation reactors 2, 3 is assigned a hydrogen gas source 8. A power generation unit (not shown in detail) serves as the hydrogen gas source 8, 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 (not shown), in which water is separated into hydrogen gas and oxygen gas by means of electrical current.

[0051] The hydrogen gas can be fed into a hydrogen gas line 9, in particular via intermediate storage in a hydrogen buffer storage (not shown), and conveyed to the respective hydrogenation reactor 2, 3. By switching the hydrogenation reactors 2, 3 on and / or off, the hydrogen buffer storage can be made comparatively small, since fluctuations in the hydrogen gas release can be compensated for by the dynamic hydrogenation process. The process is particularly economical. The hydrogen buffer storage has, in particular, a maximum volume of no more than 1000 l, in particular no more than 500 l, and in particular no more than 100 l.In particular, the theoretically required buffer storage volume can be reduced by connecting and / or disconnecting the hydrogenation reactors 2, 3, in particular by at least 10% relative to the nominal hydrogen buffer storage volume that would be required without the hydrogenation reactors 2, 3, in particular by at least 20% and in particular by at least 50%. In particular, the water buffer storage is dispensable. According to the exemplary embodiment shown, a single hydrogen gas source 8 is present, which is connected to both hydrogenation reactors 2, 3. It is understood that a separate hydrogen gas source 8 can also be connected to each of the hydrogenation reactors 2, 3.

[0052] A discharge line 10 is connected to each of the hydrogenation reactors 2, 3, by means of which the hydrogen carrier medium hydrogenated in the respective hydrogenation reactor 2, 3 can be discharged and supplied for further use. A hydrogen carrier medium sink 11 is used for this purpose, in particular, whereby a hydrogen carrier medium sink 11 can be connected to each hydrogenation reactor 2, 3. Alternatively, a common hydrogen carrier medium sink 11 can also be provided for several, in particular for all, hydrogenation reactors 2, 3.

[0053] The hydrogen carrier medium sink 11 is, in particular, a storage container in which the hydrogenated hydrogen carrier medium can be stored. Additionally or alternatively, the hydrogen carrier medium sink 11 can be an interface at which the hydrogenated hydrogen carrier medium can be added, for example, to a transport vehicle and / or into a pipeline network.

[0054] A return line 12 is connected to each discharge line 10 to return hydrogenated hydrogen carrier medium from the respective hydrogenation reactor 2, 3 to this hydrogenation reactor 2, 3. In order to specifically influence the respective fluid flow, in particular along the return line 12, a pump 13 is arranged along each return line 12. In particular, by appropriately controlling the pump 13, the ratio of the mass flows of the hydrogen carrier medium with the initial degree of hydrogenation HGo from the hydrogen carrier medium source 6 and the mass flow of the returned hydrogen carrier medium with the increased, first degree of hydrogenation HGi via the return line 12 can be specifically adjusted, i.e., adjusted.

[0055] The reactor arrangement 1 further comprises a purely schematically illustrated control unit 14, which is in particular in signal communication with the pumps 13. The control unit 14 enables the pumps 13 to be controlled in such a way that the mass flow of hydrogen carrier medium can be specifically adjusted. The signal connection of the control unit 14 is particularly designed as a wired connection. However, the signal connection can also be implemented wirelessly, in particular as a radio connection, as indicated in Fig. 1 by the symbol 15.

[0056] The respective hydrogenation reactor 2, 3 with the return line 12 and the pump 13 each form a hydrogenation module 16, designated as a whole by 16. The hydrogenation modules 16 are coupled to one another by means of the heat exchanger 4, in particular connected in parallel.

[0057] A purification unit 17 is arranged along the discharge line 10, particularly upstream of the hydrogen carrier medium sink 11. The purification unit 17 can also be part of the hydrogenation module 16 and, in this case, is arranged particularly upstream of the branch of the return line 12. The purification unit 17 is designed particularly as a distillation unit and enables, in particular, the purification of impurities that are formed particularly as degradation products in the hydrogen carrier medium and are present in admixture therein.

[0058] A method for operating the reactor arrangement 1 is explained in more detail below. The method serves, in particular, to hydrogenate the hydrogen carrier medium with hydrogen gas, which is provided in particular in a fluctuating manner, i.e., under fluctuating supply conditions. During normal operation, in particular when sufficient hydrogen gas can be provided by the hydrogen gas source 8 or at least sufficient hydrogen gas is stored in the hydrogen buffer storage units (not shown), the first hydrogenation reactor 2 and, if appropriate, the second hydrogenation reactor 3 are operated at nominal load. If appropriate, the hydrogenation reactors 2, 3 are operated at maximum load.

[0059] The heat generated during hydrogenation can be transferred as heat flow Q via the heat exchanger 4 to the at least one heat absorption unit 5 and in particular stored there.

[0060] To prevent overheating of the hydrogenation reactors 2, 3 and, in particular, to better adapt the respective hydrogenation process to the respective process conditions, the recirculated amount of hydrogen carrier medium can be specifically adjusted via the respective pump 13 along the recirculation line 12. The larger the recirculated amount of hydrogen carrier medium, the lower the thermodynamic driving force of the hydrogenation process in the respective hydrogenation reactor 2, 3. The reaction rate in the respective hydrogenation reactor 2, 3 and the resulting heat generation can be throttled accordingly.

[0061] If less and, in particular, insufficient hydrogen gas is made available for regular hydrogenation operation, it is possible to throttle the output of one or more hydrogenation reactors, i.e. to operate them with reduced hydrogen gas consumption. The output is throttled in particular by reducing the amount of hydrogen carrier medium supplied and in particular by recycling already hydrogenated hydrogen medium. In particular, the mixing ratio between fresh hydrogen carrier medium and recycled hydrogen carrier medium can be varied and flexibly adjusted during operation of the hydrogenation reactors 2, 3. It is particularly conceivable that essentially hydrogen carrier medium is recycled from the hydrogenation reactors 2, 3 and only as much fresh hydrogen carrier medium is supplied and hydrogenated in the hydrogenation reactors 2, 3 to cover the heat loss due to the exothermicity of the hydrogenation reaction.In particular, this ratio of fresh hydrogen carrier medium supplied to returned hydrogen carrier medium is at most 1:2, in particular at most 1:5, in particular at most 1:10, in particular 1:100 and in particular 1:1000.

[0062] It is particularly advantageous if such hydrogenation reactors are operated in a so-called self-sustaining mode, which, in particular, has a neutral heat balance. This means that in the self-sustaining mode, the respective hydrogenation reactor 2, 3 hydrogenates just enough hydrogen carrier medium so that the heat generated as a result of the hydrogenation reaction is sufficient to maintain the temperature level in the hydrogenation reactor 2, 3. For the reaction dynamics, it is advantageous if the pressure level in the hydrogenation reactors 2, 3 is maintained. In the self-sustaining mode, the energy requirement is at most 10% based on the nominal load of the respective hydrogenation reactor 2, 3, in particular at most 5%, in particular at most 3%, and in particular at most 1%.

[0063] It has been recognized that it is advantageous to operate the hydrogenation reactors 2, 3 in self-sustaining mode to prevent a complete shutdown of the reactors. This allows the heat stored in the hydrogenation reactor 2, 3 to be retained with reduced power consumption. In particular, the reactor arrangement thus exhibits increased flexibility. A spontaneous increase in power can be implemented easily, since, in particular, longer start-up times for one or more hydrogenation reactors are unnecessary. The hydrogenation reactor can, in particular, be returned to a regular operating state directly from the self-sustaining mode. Returning to the regular operating state is facilitated if the pressure level in the respective hydrogenation reactor 2, 3 is maintained, in particular, sustained, even during the self-sustaining mode.

[0064] In particular, an operating state is conceivable in which all hydrogenation reactors 2, 3 are operated in self-sustaining mode.

[0065] In an alternative operating state, in which the available hydrogen gas is insufficient to operate all hydrogenation reactors 2, 3 in self-sustaining mode, individual reactors can be operated in a so-called hot standby mode. In this hot standby mode, a heat flow Q is supplied to the hydrogenation reactor 2, 3 operating in this way from an external heat source. This eliminates the need for a hydrogenation reaction to take place in the hydrogenation reactor 2, 3 operating in hot standby mode. The hydrogenation reactor 2, 3 in hot standby mode is inactive and is heated exclusively by external heat.

[0066] It is conceivable that another hydrogenation reactor 2, 3 serves as the external heat source, the waste heat of which is used accordingly. It can therefore be particularly advantageous to use hydrogen gas in a hydrogenation reactor 2, 3 to generate waste heat there, which can be used as external heat for the hot standby mode of other hydrogenation reactors 2, 3. An advantageous mode of operation is characterized in that, particularly depending on the availability of heat and / or hydrogen, it is possible to flexibly switch between the hot standby mode, in which an external heat source is required, and the self-sustaining mode using a hydrogen source. In particular, the respective hydrogenation reactors 2, 3 can be placed in the respective state.

[0067] According to a further variant, excess reaction heat, which arises particularly during higher load operations and is temporarily stored in a heat storage device, can be used for later energy requirements. This is particularly the case when the heat sink 5 is operated batchwise, for example by discontinuous purification of the hydrogen carrier medium during peak load times. In this case, at least one additional heat consumer can be provided for buffering and / or optimized use of heat. The hydrogenation reaction takes place continuously, in particular, and the heat removal can be realized batchwise. This is particularly relevant when continuous heat removal is not feasible, for example because the heat sink provided and in particular its heat absorption capacity is insufficient. In this case, continuous heat removal is not possible.

[0068] This also applies if there is a risk of overloading the heat sink because the peak load exceeds the heat absorption capacity. It has been found that the purification of hydrogen carrier medium, particularly in a distillation column, can create a batch heat consumer, i.e., a batch heat sink. This makes it possible to carry out the purification of the hydrogen medium, particularly exclusively during peak load times. It may be advantageous to maintain a supply of contaminated hydrogen carrier medium in order to carry out and start the purification of the contaminated hydrogen medium during peak load in order to provide a sufficient heat sink.

[0069] An example of batch operation of reactor assembly 1 is operation of reactor assembly 1 taking into account purification of the hydrogen carrier medium. During regular operation of reactor assembly 1, degradation of the hydrogen carrier medium may occur. These degradation products can be purified from the hydrogen carrier medium by means of purification unit 17, in particular by distillation. The cleaning takes place, in particular, at regular intervals. In particular, the cleaning takes place batchwise during periods of energy peak demand and / or when there is a correspondingly high supply of contaminated, i.e., unpurified, hydrogen carrier medium.

[0070] In particular, if the heat transfer from the hydrogenation process is not stabilized in reactor assembly 1 and excess heat is temporarily stored in a heat storage facility, the temporarily stored heat can be used to purify the hydrogen carrier medium. Contaminated hydrogen carrier medium, i.e., hydrogen carrier medium with an elevated proportion of degradation products, could be provided in reactor assembly 1 and purified, particularly during high-energy times. The purified hydrogen carrier medium could be re-added to the regular hydrogen carrier medium cycle in reactor assembly 1.By storing degraded hydrogen carrier medium for the purification unit 17, the availability of the hydrogen carrier medium for hydrogenation is at least indirectly increased, without, for example, requiring the hydrogen carrier medium sources 6 to be larger or the corresponding logistics for supplying the corresponding hydrogen carrier medium to be more frequently used. The purification unit 17 can serve as an intermediate hydrogen carrier medium storage facility.

[0071] Degradation products in the hydrogen carrier medium are particularly higher-boiling aromatic hydrocarbons, especially fluorenes, anthracenes, and tetrazenes. The degradation products differ from the hydrogen carrier medium in particular due to their physiochemical properties, in particular boiling point, polarity, molecular size, and / or density. Due to these differences, the degradation products can be separated particularly preferably by distillation and / or by means of a centrifuge and / or by means of a separation membrane. Additionally or alternatively, adsorptive purification is also possible using an adsorber such as zeolite, activated carbon, silicon oxide, and / or aluminum oxide. The purification unit 17 is in particular directly connected to the heat exchanger 4, in particular the associated heat exchanger line. The purification unit 17 can in particular be continuously supplied with waste heat from the hydrogenation reactors 2, 3.Additionally or alternatively, temporarily stored heat from the heat accumulator 5 can be released to the cleaning units 17.

[0072] It is also possible for the energy required for purification to be provided during peak load times instead of transferring the heat to the heat storage unit 5. In this case, the purification unit 17 would be operated intermittently depending on the heat supply from the hydrogenation reactors 2, 3. By utilizing the reaction energy from the hydrogenation processes, particularly at energy-rich locations, for the purification of the hydrogen carrier medium, the overall economic efficiency can be increased and the process can be optimized and thus operated more economically due to the more efficient use of heat from fluctuating hydrogen sources.

[0073] Another alternative mode of operation of the reactor assembly 1 involves a desalination plant serving as the heat absorption unit 5. The desalination plant serves, in particular, to desalinate seawater, so that the desalinated seawater can subsequently be fed into an electrolysis process to produce hydrogen gas. The desalination plant can be used continuously and / or intermittently in the reactor assembly 1.

[0074] A second embodiment is described below with reference to Fig. 2. Structurally identical parts are given 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."

[0075] A key difference in the reactor arrangement 1a is that the hydrogenation modules 16a each have two hydrogenation reactors 2, 18 and 3, 19, respectively. The two hydrogenation reactors 2, 18 and 3, 19, which are arranged within a hydrogenation module 16a, are connected in series. This means that an outlet of the upstream, first hydrogenation reactor 2, 3 is fluidly connected, in particular directly, to the inlet of the second hydrogenation reactor 18 and 19, respectively. For this purpose, a connecting line 20 is arranged between each of the two hydrogenation reactors 2, 18 and 3, 19, respectively, of a hydrogenation module 16a. The connecting line 20 each has a branch line to the return line 12.

[0076] At the outlet of the second hydrogenation reactor 18, 19, an additional return line 21 is optionally connected, which is branched off from the discharge line 10. Each additional return line 21 has an additional pump 22. The additional return line 21 opens into the return line 12.

[0077] The first hydrogenation reactor 2, 3 is referred to as the starter reactor. The downstream second hydrogenation reactor 18, 19 is referred to as the finisher reactor. It has been found that a multi-stage, in particular two-stage, hydrogenation of the hydrogen carrier medium can be carried out particularly advantageously in the series-connected hydrogenation reactors 2, 18 and 3, 19, respectively, in particular with more efficient use of the catalyst material. In particular, the overall requirement for catalyst material is reduced. In particular, the reaction temperature in the second hydrogenation reactor 18, 19 can be kept comparatively low, in particular at less than 250°C, in particular at less than 240°C, and in particular at most 230°C. The absolute amount of heat that can be released in the second hydrogenation reactor 18, 19 is reduced, in particular due to the increased initial degree of hydrogenation. This results in a reduced reactant temperature with the corresponding plant control.

[0078] In the first hydrogenation reactor 2, 3, in particular, a deliberately incomplete hydrogenation takes place, so that the first degree of hydrogenation HGi of the hydrogen carrier medium upon leaving the first hydrogenation reactor 2, 3 is at most 95%, in particular at most 90%, in particular at most 85% and in particular at most 80%.

[0079] In the second hydrogenation reactor 18, 19 arranged downstream, a so-called final hydrogenation takes place to a second degree of hydrogenation HG2 of at least 95%, in particular at least 99%, and in particular at least 99.999%. Heat extraction takes place in particular at the first hydrogenation reactors 2, 3, since the comparatively higher temperatures occur there. Accordingly, the first hydrogenation reactor 2, 3, in particular, can be used as an external heat source for one of the other hydrogenation reactors in hot standby mode.

[0080] Additional heat extraction can also occur at the second hydrogenation reactors 18, 19. In particular, heat is provided there at a temperature level that is comparatively lower than the temperature level of the first hydrogenation reactors 2, 3. Nevertheless, the temperature level of the heat provided by the second hydrogenation reactors 18, 19 is suitable for heat consumers. The overall efficiency of the process is thereby increased.

Claims

Patent claims 1. Process for hydrogenating a hydrogen carrier medium comprising the process steps of catalytic hydrogenation of the hydrogen carrier medium in a hydrogenation reactor (2, 3; 2, 3, 18, 19), targeted removal of waste heat generated during hydrogenation from the hydrogenation reactor (2, 3) to at least one heat absorption unit (2, 3, 5, 17) by means of a heat exchanger (4).

2. Method according to claim 1, characterized by supplying hydrogen gas from a hydrogen buffer storage into the hydrogenation reactor (2, 3).

3. Method according to one of the preceding claims, characterized in that at least one parallel hydrogenation reactor (3) is provided, which is operated in a hydrogenation operation for the catalytic hydrogenation of the hydrogen carrier medium or in a regeneration operation for the reactivation of hydrogenation catalyst material.

4. Method according to claim 3, characterized in that the waste heat is transferred to the at least one parallel hydrogenation reactor (3), in particular connected in parallel with the hydrogenation reactor (2), as the at least one heat absorption unit.

5. Method according to one of the preceding claims, characterized in that the hydrogenation reactor (2; 2, 18) and / or the at least one parallel hydrogenation reactor (3; 3, 19) is operated with a neutral heat balance.

6. Method according to claim 5, characterized in that the supply of hydrogen, in particular the amount of hydrogen supplied, is controlled in the hydrogenation reactor (2; 2, 18) and / or in the at least one parallel hydrogenation reactor (3; 3, 19), in particular by means of a control unit (14).

7. Method according to one of the preceding claims, characterized in that the hydrogenation reactor (2; 2, 18) and / or the at least one parallel hydrogenation reactor (3; 3, 19) are heated by means of an external heating source (2), in particular for hot standby operation.

8. Method according to claim 7, characterized by controlling different operating modes of the hydrogenation reactor (2; 2, 18) and / or the at least one parallel hydrogenation reactor (3; 3, 19) such that a minimum temperature level and / or a minimum pressure level is maintained in hot standby operation and / or in self-maintenance operation.

9. Method according to claim 7 or 8, characterized in that the amount of heat supplied to the hydrogenation reactor (2; 2, 18) and / or the at least one parallel hydrogenation reactor (3; 3, 19) by means of the external heat source (2) is controlled, in particular by means of a control unit (14).

10. Method according to one of claims 7 to 9, characterized in that the hydrogenation reactor (2) serves as the external heating source for the at least one parallel hydrogenation reactor (3; 3, 19).

11. Method according to one of the preceding claims, characterized by storing transferred waste heat in a heat storage unit (5) as at least one heat absorption unit.

12. Reactor arrangement for hydrogenating a hydrogen carrier medium comprising a. a hydrogenation reactor (2, 3; 2, 3, 18, 19) for catalytic hydrogenation of the hydrogen carrier medium, b. at least one heat absorption unit (2, 3, 5, 17) for absorbing heat, c. a heat exchanger (4) connecting the hydrogenation reactor (2, 3; 2, 3, 18, 19) and the at least one heat absorption unit (2, 3, 5, 17) for transferring waste heat generated during hydrogenation from the hydrogenation reactor (2, 3; 2, 3, 18, 19) to the at least one heat absorption unit (2, 3, 5, 17).

13. Reactor arrangement according to claim 12, characterized by at least one hydrogen buffer storage, which is in particular connected to the hydrogenation reactor (2, 3; 2, 3, 18, 19).

14. Reactor arrangement according to claim 12 or 13, characterized in that the at least one heat absorption unit (3) is designed as a parallel hydrogenation reactor, which is in particular connected in parallel with the hydrogenation reactor (2; 2, 18).

15. Reactor arrangement according to one of claims 12 to 14, characterized by a control unit (14), in particular for controlling the supply of hydrogen, in particular the amount of hydrogen supplied, into the hydrogenation reactor (2, 3; 2, 3, 18, 19) and / or into the at least one parallel hydrogenation reactor (3; 3, 19). 16 Reactor arrangement according to one of claims 12 to 15, characterized by an external heating source (2) for heating the hydrogenation reactor (2, 3; 2, 3, 18, 19) and / or the at least one parallel hydrogenation reactor (3; 3, 19), in particular for hot standby operation.

17. Reactor arrangement according to one of claims 12 to 16, characterized in that the at least one heat absorption unit is designed as a heat storage unit (5) for storing transferred waste heat and / or as a heat consumer (3, 17) for consuming transferred waste heat.

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