JP2016040218A - Dehydrogenation system and operation method of dehydrogenation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dehydrogenation system capable of suppressing deterioration of a dehydrogenation catalyst.SOLUTION: A control unit 23 places the inside of a reaction vessel 31 into an atmosphere of hydrogen-containing gas through a hydrogen supply unit 22 when supply of raw materials to a dehydrogenation reactor 3 by a raw material supply unit 21 is stopped. In this state, the control unit 23 maintains a condition of a hydrogenation reaction rate being larger than a dehydrogenation reaction rate as a reaction condition for the dehydrogenation reactor 3. Consequently, hydrogenation reaction progresses between hydrogen in the hydrogen-containing gas and remaining dehydrogenated products in the reaction vessel 31. By hydrogenating the remaining dehydrogenated products in this manner, deterioration of a dehydrogenation catalyst can be suppressed.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a dehydrogenation system that performs a dehydrogenation reaction and a method for operating the dehydrogenation system.

As a conventional dehydrogenation system, a system that generates and supplies hydrogen from a raw material by a catalytic reaction is known (see, for example, Patent Document 1). The dehydrogenation system of Patent Document 1 is a tank for storing a raw material aromatic hydrocarbon hydride, a reaction for obtaining hydrogen by supplying a raw material supplied from the tank to a dehydrogenation catalyst and performing a dehydrogenation reaction. Equipped with a bowl.

JP 2006-232607 A

  In a system that obtains hydrogen using a dehydrogenation catalyst, such as the dehydrogenation system described in Patent Document 1, if the dehydrogenation catalyst deteriorates, the conversion rate from raw material to hydrogen decreases. It is important to suppress the deterioration of the catalyst. On the other hand, before and after the dehydrogenation reaction treatment, the inside of the reactor may be filled with an inert gas such as nitrogen gas, and the dehydrogenation catalyst may be held without being exposed to the outside air. There is room for improvement in order to appropriately prevent catalyst deterioration. In this technical field, a dehydrogenation system capable of suppressing deterioration of a dehydrogenation catalyst is desired.

  Then, an object of this invention is to provide the operating method of the dehydrogenation system which can suppress degradation of a dehydrogenation catalyst, and a dehydrogenation system.

  A dehydrogenation system according to the present invention includes a reaction vessel that circulates a raw material containing organic hydride, and a dehydrogenation that is disposed in the reaction vessel and converts the organic hydride into hydrogen and a dehydrogenated product by a dehydrogenation reaction. A dehydrogenation reactor including a catalyst, a raw material supply unit that supplies a raw material to the dehydrogenation reactor, a hydrogen supply unit that supplies a hydrogen-containing gas containing hydrogen to the dehydrogenation reactor, and a dehydrogenation reaction A heating unit that supplies heat to the reactor, and a control unit, and the control unit uses the hydrogen supply unit to evacuate the inside of the reaction vessel when the supply of the raw material to the dehydrogenation reactor is stopped. A hydrogen-containing gas atmosphere, heat is supplied to the dehydrogenation reactor by the heating unit, and the dehydrogenation reactor reaction conditions are such that the hydrogenation reaction rate is greater than the dehydrogenation reaction rate. With the And Temu standby state.

  When the dehydrogenation reaction is performed in the dehydrogenation reactor, the dehydrogenated product may remain in the reaction vessel. In this case, the remaining dehydrogenation product reacts with the dehydrogenation catalyst, coke is deposited on the surface of the dehydrogenation catalyst, and the dehydrogenation catalyst may be deteriorated. In the dehydrogenation system according to the present invention, when the control unit stops supplying the raw material to the dehydrogenation reactor by the raw material supply unit, the hydrogen supply unit makes the atmosphere of the hydrogen-containing gas in the reaction vessel. At the same time, heat is supplied to the dehydrogenation reactor by the heating unit. In this state, the control unit maintains a condition that the hydrogenation reaction rate is higher than the dehydrogenation reaction rate as the reaction condition of the dehydrogenation reactor. Thereby, in the reaction vessel, the hydrogenation reaction proceeds between hydrogen in the hydrogen-containing gas and the remaining dehydrogenated product. By thus hydrogenating the remaining dehydrogenated product, it is possible to suppress the deterioration of the dehydrogenation catalyst.

  In the dehydrogenation system according to the present invention, the control unit is a reaction region in which the equilibrium conversion rate of the organic hydride is less than 50% among the reaction regions determined by the relationship between the reaction temperature of the dehydrogenation reactor and the reaction pressure. The reaction temperature and reaction pressure may be maintained. The reaction temperature and reaction pressure of the dehydrogenation reactor can be freely set within the range satisfying such a reaction region.

  In the dehydrogenation system according to the present invention, the control unit may maintain the reaction temperature of the dehydrogenation reactor at 200 ° C. or lower. As a result, regardless of the reaction pressure of the dehydrogenation reactor, the hydrogenation reaction rate can be made higher than the dehydrogenation reaction rate.

  In the dehydrogenation system according to the present invention, the control unit may maintain the reaction pressure of the dehydrogenation reactor at or above an absolute pressure of 0.1 MPaA (hereinafter, A is added as an absolute pressure). The control unit may keep the reaction pressure of the dehydrogenation reactor at 0.3 MPaA or more.

  The operation method of the dehydrogenation system according to the present invention is the above-described operation method of the dehydrogenation system, and when the supply of the raw material to the dehydrogenation reactor by the raw material supply unit is stopped, the hydrogen supply unit The reaction vessel is filled with a hydrogen-containing gas atmosphere, heat is supplied to the dehydrogenation reactor by the heating unit, and the reaction conditions of the dehydrogenation reactor are the hydrogenation reaction compared to the dehydrogenation reaction rate. A system standby state is set in a state where conditions for increasing the speed are maintained.

  According to the operating method of the dehydrogenation system concerning the present invention, the same operation and effect as the above-mentioned dehydrogenation system can be obtained.

  According to the present invention, it is possible to suppress deterioration of the dehydrogenation catalyst.

It is a block diagram which shows the structure of a hydrogen supply system provided with the dehydrogenation system which concerns on embodiment of this invention. It is a block diagram which shows the structure of the dehydrogenation system which concerns on embodiment of this invention. It is a graph which shows the relationship between the reaction temperature of a dehydrogenation reactor, and MCH equilibrium conversion. It is a graph which shows the relationship between reaction pressure and reaction temperature when MCH equilibrium conversion rate will be 50%. It is a flowchart which shows the control processing by the dehydrogenation system which concerns on embodiment of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a block diagram illustrating a configuration of a hydrogen supply system including a dehydrogenation system according to the present embodiment. This hydrogen supply system 100 uses organic hydride as a raw material. An organic hydride is preferably a hydride obtained by reacting a large amount of hydrogen produced in a refinery with an aromatic hydrocarbon. The organic hydride can be transported to the hydrogen supply system 100 as a liquid fuel by a tank lorry as in the case of gasoline.

  An organic hydride is a hydride of an organic compound having an unsaturated bond, and is converted into a dehydrogenation reaction product containing hydrogen and a dehydrogenated product (an organic compound having an unsaturated bond) using a dehydrogenation catalyst. be able to. In this embodiment, description is made using methylcyclohexane (hereinafter referred to as MCH) as the organic hydride, but the present invention is not limited to this.

  An organic compound having an unsaturated bond is an organic compound having one or more double bonds or triple bonds in the molecule. As the double bond, carbon-carbon double bond (C = C), carbon-nitrogen double bond (C = N), carbon-oxygen double bond (C = O), nitrogen-oxygen double bond (N = O). Examples of the triple bond include a carbon-carbon triple bond and a carbon-nitrogen triple bond. The organic compound having an unsaturated bond is preferably a liquid organic compound under normal temperature and pressure from the viewpoints of storage properties and transportability.

  Examples of the organic compound having an unsaturated bond include olefins, dienes, acetylenes, benzene, carbon chain-substituted aromatics, hetero-substituted aromatics, polycyclic aromatics, Schiff bases, and heteroaromatics. , Hetero 5-membered ring compounds, quinones, and ketones. Examples of olefins include ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecene, and the like. Examples of dienes include allene, butadiene, pentadiene, hexadiene, hebutadiene, octadiene, piperylene, isoprene and the like. Examples of acetylenes include acetylene, propyne, and vinyl acetylene. Examples of the carbon chain-substituted aromatics include alkyl-substituted aromatics. Examples of the alkyl-substituted aromatics include toluene, xylene, trimethylbenzene, ethylbenzene, cumene, benzoic acid and the like. Examples of hetero-substituted aromatics include anisole, dimethoxybenzene, phenol, aniline, N, N-dimethylaniline and the like. Examples of polycyclic aromatics include naphthalene, methylnaphthalene, anthracene, tetracene, phenanthrene, tetralin, and azulene. Examples of Schiff bases include 2-aza-hept-1-en-1-yl-cyclohexane. Heteroaromatics include pyridine, pyrimidine, quinoline, isoquinoline and the like. Examples of the hetero 5-membered ring compounds include furan, thiophene, pyrrole, and imidazole. Examples of quinones include benzoquinone and naphthoquinone. Examples of ketones include acetone and methyl ethyl ketone. Needless to say, carbon dioxide and carbon monoxide have an unsaturated bond, but are generally not regarded as organic compounds, and thus are excluded from the organic compounds having an unsaturated bond in the present embodiment. .

  Among the above unsaturated compounds, benzene, toluene, xylene, ethylbenzene, naphthalene, methylnaphthalene, tetralin and the like (hereinafter referred to as “benzene”) are water-insoluble before and after hydrogenation, and are phase separated from water. Since it is possible, it is preferable to water-soluble organic compounds such as acetone from the viewpoint of easy recovery as a product. In addition, as a water-insoluble organic compound, 1 type of compounds among benzene etc. may be sufficient, and the mixture of 2 or more types of compounds may be sufficient.

  The hydrogen supply system 100 can supply hydrogen to a fuel cell vehicle (FCV) or a hydrogen engine vehicle. The present invention can also be applied to the production of hydrogen from liquid hydrocarbon raw materials such as natural gas mainly composed of methane, LPG mainly composed of propane, or gasoline, naphtha, kerosene, and light oil.

  In the present embodiment, the hydrogen supply system 100 will be described using a hydrogen station that supplies high-purity hydrogen to the FCV 10 as an example. As shown in FIG. 1, a hydrogen supply system 100 according to this embodiment includes an MCH tank 1, a vaporizer 2, a dehydrogenation reactor 3, a gas-liquid separator 4, a toluene tank 5, a hydrogen purifier 6, and a compressor. 7, an accumulator 8, a dispenser 9, a heat source 11, cold heat sources 12 and 13, and the like. Further, the hydrogen supply system 100 includes lines L1 to L9. In the present embodiment, an example will be described in which MCH is employed as a raw material and the dehydrogenation product removed in the process of hydrogen purification is toluene. In practice, not only toluene but also unreacted MCH and a small amount of by-products and impurities are present, but in this embodiment, the same behavior as toluene is exhibited when mixed with toluene. Therefore, in the following description, what is referred to as “toluene” includes unreacted MCH and by-products.

  Lines L1 to L9 are flow paths through which MCH, toluene, hydrogen-containing gas, off-gas, or high-purity hydrogen passes. Line L1 connects MCH tank 1 and vaporizer 2. The line L2 connects the vaporizer 2 and the dehydrogenation reactor 3. Line L3 connects the dehydrogenation reactor 3 and the gas-liquid separator 4. The line L4 connects the gas-liquid separator 4 and the hydrogen purifier 6. The line L5 connects the gas / liquid separator 4 and the toluene tank 5. The line L6 connects the hydrogen purifier 6 and the compressor 7. The line L7 connects the hydrogen purifier 6 and the vaporizer 2. The line L7 functions as a recycle line for refluxing off-gas discharged from the hydrogen purifier 6 to the upstream side of the dehydrogenation reactor 3. The line L8 connects the compressor 7 and the pressure accumulator 8. Line L9 connects pressure accumulator 8 and dispenser 9.

  The MCH tank 1 is a tank that stores MCH as a raw material. MCH transported from outside by a tank lorry or the like is stored in the MCH tank 1. MCH stored in the MCH tank 1 is supplied to the vaporizer 2 via a line L1 by a compressor (not shown).

  The vaporizer 2 is a device that vaporizes MCH supplied from the MCH tank 1 via an injector or the like. The vaporized MCH is supplied to the dehydrogenation reactor 3 via the line L2 together with the off-gas supplied from the hydrogen purifier 6 via the line L7.

  The dehydrogenation reactor 3 is a device that obtains hydrogen by dehydrogenating MCH. That is, the dehydrogenation reactor 3 is a device that extracts hydrogen from MCH by a dehydrogenation reaction using a dehydrogenation catalyst. The organic hydride reaction is a reversible reaction, and the direction of the reaction changes depending on the reaction conditions (temperature, pressure) (restricted by chemical equilibrium). On the other hand, the dehydrogenation reaction is a reaction in which the number of molecules is always increased by an endothermic reaction. Therefore, high temperature and low pressure conditions are advantageous. Since the dehydrogenation reaction is an endothermic reaction, the dehydrogenation reactor 3 is supplied with heat from the heat source 11 via a heat medium. The dehydrogenation reactor 3 has a mechanism capable of exchanging heat between the MCH flowing in the dehydrogenation catalyst and the heat medium from the heat source 11. Any heat source 11 may be adopted as long as it can heat the dehydrogenation reactor 3. For example, the heat source 11 may directly heat the dehydrogenation reactor 3. For example, the MCH supplied to the dehydrogenation reactor 3 is heated by heating the vaporizer 2 or the lines L 1 and L 2. May be. Further, the heat source 11 may heat both the dehydrogenation reactor 3 and the MCH supplied to the dehydrogenation reactor 3. For example, a burner or an engine can be adopted as the heat source 11. The hydrogen-containing gas taken out by the dehydrogenation reactor 3 is supplied to the gas-liquid separator 4 via the line L3. The hydrogen-containing gas in the line L3 is supplied to the gas-liquid separator 4 in a state where the liquid toluene is contained as a mixture.

  The gas-liquid separator 4 is a tank that separates toluene from the hydrogen-containing gas. The gas-liquid separator 4 gas-liquid separates hydrogen as a gas and toluene as a liquid by storing a hydrogen-containing gas containing toluene as a mixture. The gas-liquid separator 4 is cooled by a cooling medium from the cold heat source 12. The gas-liquid separator 4 has a mechanism capable of exchanging heat between the hydrogen-containing gas in the gas-liquid separator 4 and the cooling medium from the cold heat source 12. As long as the cold-heat source 12 can cool the gas-liquid separator 4, what kind of thing may be employ | adopted. For example, a cooler such as a chiller can be employed as the cold heat source 12. The toluene separated by the gas-liquid separator 4 is supplied to the toluene tank 5 via the line L5. The hydrogen-containing gas separated by the gas-liquid separator 4 is supplied to the hydrogen purifier 6 via the line L4. When the hydrogen-containing gas is cooled, a part of the gas (toluene) is liquefied and can be separated from the gas (hydrogen) that is not liquefied by the gas-liquid separator 4. The efficiency of the separation is improved when the gas is at a low temperature, and the liquefaction of toluene further proceeds when the pressure is increased.

  The toluene tank 5 is a tank that stores liquid toluene separated by the gas-liquid separator 4.

  The hydrogen purifier 6 removes the dehydrogenation product (toluene in this embodiment) from the hydrogen-containing gas obtained in the dehydrogenation reactor 3 and gas-liquid separated in the gas-liquid separator 4. Thereby, the hydrogen purifier 6 purifies the hydrogen-containing gas to obtain high-purity hydrogen (purified gas). The obtained high-purity hydrogen is supplied to the line L6, and the off gas containing hydrogen and a dehydrogenation product is discharged to the line L7. The off gas supplied to the line L7 is supplied to the vaporizer 2 through a compressor (not shown), and is supplied to the dehydrogenation reactor 3 through the line L2.

  The hydrogen purifier 6 differs depending on the hydrogen purification method employed. Specifically, when membrane separation is used as the hydrogen purification method, the hydrogen purifier 6 is a hydrogen separation apparatus including a hydrogen separation membrane, and is a PSA (Pressure Swing Adsorption) method. Alternatively, when a TSA (Temperature Swing Adsorption) method is used, the adsorption / removal apparatus includes a plurality of adsorption towers that store adsorbents that adsorb impurities.

  The case where the hydrogen purifier 6 uses membrane separation will be described. In this method, a hydrogen-containing gas pressurized to a predetermined pressure by a compressor (not shown) is permeated through a membrane heated to a predetermined temperature, thereby removing dehydrogenation products and high-purity hydrogen gas. (Purified gas) can be obtained. The pressure of the permeated gas that has permeated the membrane is lower than the pressure before permeating the membrane. On the other hand, the pressure of the non-permeating gas that has not permeated the membrane is substantially the same as the predetermined pressure before permeating the membrane. At this time, the non-permeating gas that has not permeated the membrane corresponds to the off-gas of the hydrogen purifier 6.

  The type of membrane applied to the hydrogen purifier 6 is not particularly limited, and is a porous membrane (separated by molecular flow, separated by surface diffusion flow, separated by capillary condensation, or separated by molecular sieving. Etc.) and non-porous membranes can be applied. As a membrane applied to the hydrogen purifier 6, for example, a metal membrane (PdAg, PdCu, Nb, etc.), a zeolite membrane, an inorganic membrane (silica membrane, carbon membrane, etc.), a polymer membrane (polyimide membrane, etc.) Can be adopted.

  The hydrogen recovery rate of the hydrogen purifier 6 by membrane separation is 70 to 90%. The separation factor of “hydrogen / toluene” of the membrane used in the hydrogen purifier 6 is preferably 1000 or more, and more preferably 10,000 or more.

  A case where the PSA method is adopted as a method for removing the hydrogen purifier 6 will be described. The adsorbent used in the PSA method has the property of adsorbing toluene contained in the hydrogen-containing gas under high pressure and desorbing the adsorbed toluene under low pressure. The PSA method utilizes such properties of the adsorbent. That is, by setting the inside of the adsorption tower at a high pressure, toluene contained in the hydrogen-containing gas is adsorbed and removed by the adsorbent to obtain high-purity hydrogen gas (purified gas). If the adsorption function of the adsorbent in the adsorption tower decreases due to adsorption, the toluene adsorbed on the adsorbent is desorbed and a part of the purified gas removed is caused to flow backward by lowering the pressure in the adsorption tower. By removing the desorbed toluene from the inside of the adsorption tower, the adsorption function of the adsorbent is regenerated (at this time, the hydrogen containing at least hydrogen and toluene discharged by removing toluene from the inside of the adsorption tower) The gas corresponds to the off-gas from the hydrogen purifier 6).

  The method for adjusting the pressure in the adsorption tower is not particularly limited, and can be adjusted for each adsorption tower by, for example, closing a valve provided for each adsorption tower. Therefore, for the adsorption tower in which the adsorption function of the adsorbent is lowered, the adsorbent is regenerated by reducing the pressure and off-gas is discharged. On the other hand, with respect to the remaining adsorption tower, toluene contained in the hydrogen-containing gas is removed by being adsorbed to the adsorbent by pressurization and high-purity hydrogen is obtained. When the adsorbent regeneration for the adsorption tower being regenerated is completed, the adsorption tower starts to remove toluene by pressurization and obtains high-purity hydrogen. On the other hand, for all or part of the adsorption tower from which toluene has been removed, regeneration of the adsorbent is started by reducing the pressure and off-gas is discharged. Thus, by repeatedly switching the adsorption tower for regeneration and the adsorption tower for removing toluene, the hydrogen supply system 100 as a whole can obtain high-purity hydrogen and off-gas continuously. The hydrogen recovery rate when the hydrogen purifier 6 employs the PSA method is about 60 to 90%, depending on the number of adsorption towers.

  A case where the TSA method is employed as a method for removing the hydrogen purifier 6 will be described. The adsorbent used in the TSA method has the property of adsorbing toluene contained in the hydrogen-containing gas at room temperature and desorbing the adsorbed toluene at high temperature. The TSA method utilizes such properties of the adsorbent. That is, by setting the inside of the adsorption tower to room temperature, toluene contained in the hydrogen-containing gas is adsorbed and removed by the adsorbent to obtain high-purity hydrogen gas (high-purity hydrogen). If the adsorption function of the adsorbent in the adsorption tower is reduced due to adsorption, the toluene adsorbed on the adsorbent is desorbed by raising the temperature in the adsorption tower, and a part of the high-purity hydrogen that has been removed is backflowed. By removing the desorbed toluene from the adsorption tower, the adsorption function of the adsorbent is regenerated (at this time, at least hydrogen and hydrogen containing toluene discharged by removing toluene from the adsorption tower) The contained gas corresponds to the off-gas from the hydrogen purifier 6).

  The method for adjusting the temperature in the adsorption tower is not particularly limited. For example, the temperature can be adjusted for each adsorption tower by an operation such as switching ON / OFF of a heater provided for each adsorption tower. Therefore, for the adsorption tower in which the adsorption function of the adsorbent is lowered, the adsorbent is regenerated and the off-gas is discharged by raising the temperature. On the other hand, with respect to the remaining adsorption towers, toluene contained in the hydrogen-containing gas is removed by adsorbing the adsorbent by maintaining the temperature at room temperature. When the adsorbent regeneration for the adsorption tower being regenerated is completed, the removal of toluene is started and high purity hydrogen is obtained for the adsorption tower by keeping the inside of the adsorption tower at room temperature. On the other hand, for all or part of the adsorption tower from which toluene has been removed, regeneration of the adsorbent is started and the off-gas is discharged by raising the temperature in the adsorption tower. Thus, by repeatedly switching the adsorption tower for regeneration and the adsorption tower for removing toluene, the hydrogen supply system 100 as a whole can obtain high-purity hydrogen and off-gas continuously. The hydrogen recovery rate when the hydrogen purifier 6 employs the TSA method is about 60 to 90%, depending on the number of adsorption towers.

  The compressor 7 puts the high purity hydrogen obtained in the hydrogen purifier 6 into a high pressure state. The compressor 7 makes high-purity hydrogen into a high-pressure state at a pressure of 20 to 90 MPa, for example. The compressor 7 is in a high pressure state so that high purity hydrogen can be supplied to the FCV 10, and then supplied to the pressure accumulator 8 via the line L8. In addition, according to the target pressure, it is good also as a structure which provides multiple compression units which compress, and performs compression in steps.

  The pressure accumulator 8 stores high purity hydrogen in a high pressure state. The high purity hydrogen stored in the pressure accumulator 8 is supplied to the FCV 10 by the dispenser 9 via the line L9. Since the pressure accumulator 8 can store a certain amount of high-purity hydrogen in the hydrogen supply system 100, hydrogen can be stably supplied to the FCV 10. However, since the pressure accumulator 8 is not essential for supplying hydrogen, it may be omitted. The high purity hydrogen passing through the line L9 is cooled by the cooling medium from the cold heat source 13. The line L9 has a mechanism capable of exchanging heat between the high purity hydrogen flowing through the line L9 and the cooling medium from the cold heat source 13. Any cooling source 13 may be used as long as it can cool the high purity hydrogen flowing through the line L9. For example, a cooler such as a chiller can be employed as the cold heat source 13.

  Next, the configuration of the dehydrogenation system 150 according to the present embodiment will be described.

  As shown in FIG. 2, the dehydrogenation system 150 includes a dehydrogenation reactor 3, a raw material supply unit 21 that supplies a raw material containing organic hydride to the dehydrogenation reactor 3, and a dehydrogenation reactor 3. A hydrogen supply unit 22 that supplies a hydrogen-containing gas containing hydrogen, a heating unit 24 that supplies heat to the dehydrogenation reactor 3, and a control unit that controls the dehydrogenation reaction in the dehydrogenation reactor 3. 23.

  The dehydrogenation reactor 3 includes a reaction vessel 31 for circulating raw materials, a catalyst layer 32 formed by a dehydrogenation catalyst disposed in the reaction vessel 31, and a heat exchanger 33 provided around the reaction vessel 31. And. In the present embodiment, the reaction vessel 31 has a plurality of reaction tubes arranged in parallel, and a catalyst layer 32 is formed by filling each reaction tube with a dehydrogenation catalyst. The periphery of each reaction tube of the reaction vessel 31 is surrounded by a heat exchanger 33. The configuration of the heat exchanger 33 will be described later together with the description of the heating unit 24.

  The dehydrogenation catalyst constituting the catalyst layer 32 converts organic hydride into hydrogen and dehydrogenated product by a dehydrogenation reaction. As the dehydrogenation catalyst, for example, a catalyst in which platinum, ruthenium, palladium, rhodium, tin, rhenium, germanium or the like is supported on a porous carrier in which pores such as alumina are formed is used. The dehydrogenation catalyst may have a structure like a honeycomb type catalyst or a molded pellet catalyst. The dehydrogenation catalyst may deteriorate in performance due to coking depending on the use, but it can be used repeatedly by performing a recovery process to restore the original performance by calcination in the presence of oxygen. At the upstream end of each reaction tube of the reaction vessel 31, a distribution unit 34 for distributing the raw material gas flowing in from the inlet 36 of the dehydrogenation reactor 3 to each reaction tube is provided. In addition, a mixing unit 37 that aggregates and mixes the hydrogen-containing gas generated in each catalyst layer 32 is provided at the downstream end of each reaction tube. The hydrogen-containing gas mixed in the mixing unit 37 is discharged from the discharge port 38 of the dehydrogenation reactor 3.

  The raw material supply unit 21 is configured by, for example, a pump for supplying the raw material to the dehydrogenation reactor 3 from a tank in which the raw material is stored like the MCH tank 1 shown in FIG. The raw material supply unit 21 supplies the raw material to each catalyst layer 32 through the inlet 36 and the distribution unit 34 of the dehydrogenation reactor 3. The hydrogen supply unit 22 includes, for example, a pump that supplies off-gas discharged from the hydrogen purifier 6 illustrated in FIG. 1 to the dehydrogenation reactor 3, a flow rate adjustment valve, and the like. The hydrogen supply unit 22 may not supply the off gas in the hydrogen supply system 100, and may supply hydrogen from a tank or a cylinder in which hydrogen is stored. The hydrogen supply unit 22 supplies a hydrogen-containing gas to each catalyst layer 32 through the inlet 36 and the distribution unit 34 of the dehydrogenation reactor 3.

  The heating unit 24 includes a heat exchanger 33 provided in the dehydrogenation reactor 3 and a heat source 11 that supplies a heat medium to the heat exchanger 33. The heat exchanger 33 is provided so as to surround the entire reaction vessel 31 from the outer peripheral side. The heat exchanger 33 has an inlet 44 through which the heat medium flows in near the downstream end of the reaction vessel 31, and an outlet 46 through which the heat medium is discharged near the upstream end of the reaction vessel 31. doing. With such a configuration, the heat medium flows outside the reaction tubes of the reaction vessel 31, and the heat of the heat medium is supplied to the catalyst layers 32. In the configuration shown in FIG. 2, the heat medium is supplied from the inlet 44 on the outlet side of the dehydrogenation reactor 3, and the heat medium is discharged from the outlet 46 on the inlet side. However, the arrangement of the inlet 44 and the outlet 46 may be reversed. The heating unit 24 is not limited to a structure that supplies heat to the catalyst layer 32 by flowing a heat medium. For example, a heating unit such as a heater is provided around the reaction vessel 31 and the heating unit 24 directly heats from the heating unit. May be supplied.

  The control unit 23 is a general computer unit including a CPU, a memory, a storage medium, a display device, and the like, and is connected to the components of the above-described dehydrogenation system 150 and configured to control each component. Yes. The control unit 23 may also function as a control unit for controlling the entire hydrogen supply system 100 shown in FIG. The control unit 23 controls the dehydrogenation reaction in the dehydrogenation reactor 3 during the system operation of the dehydrogenation system 150. Specifically, the control unit 23 supplies the raw material to the dehydrogenation reactor 3 by controlling the raw material supply unit 21, and controls the heat source 11 to control the dehydrogenation reactor 3 through the heat medium. Supply heat to Further, the control unit 23 may adjust the reaction pressure of the dehydrogenation reaction in the dehydrogenation reactor 3 by adjusting the valve 41 provided at the inlet 36. In addition to or instead of this, the control unit 23 may adjust the reaction pressure of the dehydrogenation reaction in the dehydrogenation reactor 3 by adjusting the flow rate of the raw material supply unit 21.

  In the embodiment, the control unit 23 stops the dehydrogenation reaction in the dehydrogenation system 150 and performs dehydrogenation when waiting in a high temperature state (hot standby) in preparation for the next start-up. Control can be performed so as to suppress and recover the deterioration of the catalyst. Specifically, when the supply of the raw material to the dehydrogenation reactor 3 by the raw material supply unit 21 is stopped, the control unit 23 sets the atmosphere of the hydrogen-containing gas in the reaction vessel 31 by the hydrogen supply unit 22. At the same time, the heating unit 24 supplies heat to the dehydrogenation reactor 3. In addition, when the supply of the raw material to the dehydrogenation reactor 3 by the raw material supply unit 21 is stopped, the control unit 23 sets the reaction condition of the dehydrogenation reactor 3 as compared with the dehydrogenation reaction rate. The system is set in a standby state while maintaining a condition for increasing the hydrogenation reaction rate.

  When the supply of the raw material by the raw material supply unit 21 is stopped, the control unit 23 supplies the hydrogen-containing gas by the hydrogen supply unit 22 and each reaction tube 31 (that is, the catalyst) in the reaction vessel 31 of the dehydrogenation reactor 3. By continuously flowing the hydrogen-containing gas through the layer 32), the atmosphere of the hydrogen-containing gas can be set in the reaction vessel 31. Alternatively, the control unit 23 supplies the hydrogen-containing gas by the hydrogen supply unit 22, and seals the dehydrogenation reactor 3 in a state where each reaction tube of the reaction vessel 31 is filled with the hydrogen-containing gas. You may seal by. As described above, the hydrogen-containing gas atmosphere can also be obtained by keeping the hydrogen-containing gas in the reaction vessel 31.

  Here, with reference to FIG. 3 and FIG. 4, the conditions under which the hydrogenation reaction rate is higher than the dehydrogenation reaction rate will be described. The “condition that the hydrogenation reaction rate is higher than the dehydrogenation reaction rate” is synonymous with the “condition that the equilibrium conversion of the organic hydride is less than 50%”. Here, the equilibrium conversion rate is a theoretical conversion rate assuming a state after infinite reaction time at a predetermined reaction temperature and reaction pressure. This equilibrium conversion rate is uniquely calculated by calculation regardless of the state of the dehydrogenation catalyst.

For example, the relationship between the hydrogenation reaction and the dehydrogenation reaction when the organic hydride is MCH and the dehydrogenated product is toluene is shown in Formula (1). In Formula (1), the reaction from the right side to the left side is a dehydrogenation reaction, and the reaction from the left side to the right side is a hydrogenation reaction.

C ₆ H ₅ CH ₃ + 3H ₂ ← → C ₆ H ₁₁ CH ₃ (1)

  When the equilibrium conversion rate of MCH (organic hydride) is 50% or more, the dehydrogenation reaction is easier to proceed than the hydrogenation reaction, that is, the dehydrogenation reaction rate is higher than the hydrogenation reaction rate. It is. In this state, even if the inside of the reaction vessel 31 of the dehydrogenation reactor 3 is in a hydrogen atmosphere, the organic hydride is dehydrated rather than the reaction in which toluene remaining around the dehydrogenation catalyst becomes an organic hydride by the hydrogenation reaction. Since the reaction that becomes toluene by the nitriding reaction is superior, it is not possible to obtain the effect of suppressing and recovering the deterioration of the dehydrogenation catalyst. On the other hand, when the equilibrium conversion rate of MCH (organic hydride) is less than 50%, the hydrogenation reaction is easier to proceed than the dehydrogenation reaction, that is, the hydrogenation reaction rate is higher than the dehydrogenation reaction rate. It is a state. In this state, by making the inside of the reaction vessel 31 of the dehydrogenation reactor 3 into a hydrogen atmosphere, the organic hydride is dehydrated in the reaction in which the toluene remaining around the dehydrogenation catalyst becomes an organic hydride by the hydrogenation reaction. Since the hydrogenation reaction is superior to the reaction that results in toluene, it is possible to obtain an effect of suppressing deterioration and recovery of the dehydrogenation catalyst.

  FIG. 3 is a graph (equilibrium curve) showing the relationship between the reaction temperature of the dehydrogenation reactor 3 and the MCH equilibrium conversion rate. As shown in FIG. 3, when the reaction pressure is set to a predetermined value, the MCH equilibrium change rate changes as the reaction temperature changes. That is, in the temperature region where the reaction temperature is high, the MCH equilibrium conversion rate is close to 100%. As the reaction temperature decreases, the MCH equilibrium conversion rate decreases, and at a certain reaction temperature, the MCH equilibrium conversion rate becomes 50%. In the lower temperature range, the MCH equilibrium conversion is less than 50%. Moreover, the graph moves to the higher temperature side as the reaction pressure of the dehydrogenation reactor 3 increases. Therefore, the higher the reaction pressure in the dehydrogenation reactor 3, the higher the reaction temperature when the MCH equilibrium conversion becomes 50%.

FIG. 4 is a graph showing the relationship between the reaction pressure and the reaction temperature when the MCH equilibrium conversion rate is 50%. This graph A is created by plotting the reaction temperature and the reaction temperature when the vertical axis is the reaction temperature, the horizontal axis is the reaction pressure, and the MCH equilibrium conversion is 50% in FIG. The reaction pressure is a hydrogen partial pressure (absolute pressure). In the reaction region where the reaction temperature is lower than that in the graph A, the MCH equilibrium conversion rate is less than 50%, so that the hydrogenation reaction proceeds preferentially. The graph A is expressed by the following formula (2). x is the reaction pressure and y is the reaction temperature. However, in FIG. 3 and FIG. 4, the description is made by taking as an example the conditions when MCH is adopted as the organic hydride. However, when other substances are adopted, the conditions according to the substances are used.

y = 346.64x ^0.1273
R ² = 1 (2)

  Based on the relationship as described above, the control unit 23 performs the reaction in which the equilibrium conversion rate of the organic hydride is less than 50% in the reaction region determined by the relationship between the reaction temperature of the dehydrogenation reactor 3 and the reaction pressure. Control is performed so that the reaction temperature and the reaction pressure are maintained in the region E1. That is, the control unit 23 sets and holds the reaction temperature and the reaction pressure so as to have any value in the reaction region E1 whose reaction temperature is lower than that in the graph A shown in FIG. Note that the control unit 23 may control the reaction temperature and the reaction pressure so that the reaction temperature and the reaction pressure are maintained at constant values so as to be values in the reaction region E1. Alternatively, the control unit 23 may allow the reaction temperature and the reaction pressure to change as long as the value is in the reaction region.

  As shown in FIG. 4, the control unit 23 stores in advance data such as a map indicating the reaction region E1 in which the equilibrium conversion rate of the organic hydride is less than 50%, or acquires the reaction region E1 by calculation, The value may be set after determining whether the reaction temperature and reaction pressure of the dehydrogenation reactor 3 are within the reaction region E1. Alternatively, the control unit 23 may acquire any value (one set or a plurality of sets) in the reaction region E1 in advance, and control using the value acquired in advance when the system is on standby. . Moreover, the control part 23 may hold | maintain reaction temperature at 200 degrees C or less. As can be understood from FIG. 4, in the region where the reaction temperature is 200 ° C. or lower, the organic hydride equilibrium conversion is less than 50% regardless of the reaction pressure, and the hydrogenation reaction rate is faster than the dehydrogenation reaction rate. Become. Therefore, the control unit 23 can satisfy the condition without considering and controlling the reaction pressure. In addition, since reaction rate is very low at low temperature, it is preferable that reaction temperature shall be 100 degreeC or more. Moreover, the control part 23 may hold | maintain the reaction pressure of the dehydrogenation reactor 3 to 0.1 MpaA or more. Moreover, the control part 23 may hold | maintain the reaction pressure of the dehydrogenation reactor 3 to 0.3 MpaA or more.

  The controller 23 may control the reaction temperature so as to satisfy the above conditions in accordance with the reaction pressure of the dehydrogenation reactor 3 when the system is in a standby state. However, the control unit 23 may set the reaction temperature to 200 ° C. or less without considering the reaction pressure. Alternatively, the control unit 23 may control the reaction pressure so as to satisfy the above conditions in accordance with the reaction temperature of the dehydrogenation reactor 3 when setting the system standby state. Alternatively, the control unit 23 may control both the reaction temperature and the reaction pressure so as to satisfy the above conditions when the system is in a standby state.

  The control unit 23 controls the amount of heat supplied by the heating unit 24 when controlling the reaction temperature. For example, the control unit 23 can adjust the heat supply amount by adjusting the temperature and flow rate of the heat medium. Further, when controlling the reaction pressure, the control unit 23 adjusts the throttle of the valve 41 and the like, and adjusts the hydrogen supply amount by the hydrogen supply unit 22. The control unit 23 may grasp the reaction temperature using a temperature sensor provided in the dehydrogenation reactor 3. As the reaction temperature, for example, the temperature of the heat medium may be grasped. The control unit 23 may grasp the reaction pressure using a pressure sensor provided in the dehydrogenation reactor 3. As the reaction pressure, for example, the pressure at the hydrogen purifier inlet (L4 in FIG. 1) may be grasped.

  Next, with reference to FIG. 5, the control content when the dehydrogenation system 150 which concerns on this embodiment will be in a system standby state is demonstrated. However, the processing procedure is not limited to that shown in FIG.

  First, the control unit 23 performs a system stop process (step S10). The control unit 23 stops the supply of the raw material at least by the raw material supply unit 21. In addition, the control part 23 continues the state which is supplying the heat | fever to the dehydrogenation reactor 3 by the heating part 24 during a driving | operation. Next, the control unit 23 supplies a hydrogen-containing gas to the dehydrogenation reactor 3 (step S20). Thereby, the control unit 23 sets the atmosphere of the hydrogen-containing gas in the reaction vessel 31. Next, the control unit 23 sets a condition in which the hydrogenation reaction rate is higher than the dehydrogenation reaction rate as the reaction condition of the dehydrogenation reactor 3, and holds the condition (step S30). The control unit 23 continues the system standby state while maintaining the condition (step S40). When the process of S40 ends, the process shown in FIG. 5 ends.

  Next, the operation and effect of the dehydrogenation system 150 according to the present embodiment and the operation method of the dehydrogenation system 150 will be described.

  Here, when the dehydrogenation reaction is performed in the dehydrogenation reactor 3, the dehydrogenated product may remain in the reaction vessel 31. In this case, the remaining dehydrogenation product reacts with the dehydrogenation catalyst, coke is deposited on the surface of the dehydrogenation catalyst, and the dehydrogenation catalyst may be deteriorated. In contrast, in the dehydrogenation system 150 according to the present embodiment, the control unit 23 uses the hydrogen supply unit 22 to stop the supply of the raw material to the dehydrogenation reactor 3 by the raw material supply unit 21. While the inside of the reaction vessel 31 is made an atmosphere of a hydrogen-containing gas, heat is supplied to the dehydrogenation reactor 3 by the heating unit 24. In this state, the control unit 23 maintains a condition that the hydrogenation reaction rate is higher than the dehydrogenation reaction rate as the reaction condition of the dehydrogenation reactor 3. Thereby, in the reaction vessel 31, the hydrogenation reaction proceeds between the hydrogen in the hydrogen-containing gas and the remaining dehydrogenated product. By thus hydrogenating the remaining dehydrogenated product, it is possible to suppress the deterioration of the dehydrogenation catalyst. Also, the dehydrogenation catalyst can be recovered. Further, by supplying heat to the dehydrogenation reactor 3 by the heating unit 24 during the system standby state, the dehydrogenation reactor 3 enters a standby state (hot standby) at a high temperature. As a result, the system can be quickly activated. At this time, the system can be started more quickly by suppressing and recovering the deterioration of the dehydrogenation catalyst.

  In the dehydrogenation system 150 according to the present embodiment, the control unit 23 has an organic hydride equilibrium conversion rate of 50 in the reaction region determined by the relationship between the reaction temperature and the reaction pressure of the dehydrogenation reactor 3. The reaction temperature and reaction pressure are maintained in the reaction region E1 that is less than%. The reaction temperature and reaction pressure of the dehydrogenation reactor 3 can be freely set within the range of the reaction region E1. For example, by setting the reaction temperature high within the range of the reaction region E1, hot standby in a high temperature state becomes possible. As a result, activation can be performed quickly.

  The present invention is not limited to the above-described embodiment.

  For example, the configuration of the dehydrogenation reactor is not limited to the multi-tube type as shown in FIG. 2, and a single-tube type may be adopted. In addition, you may employ | adopt the dehydrogenation reactor of a structure like a plate type heat exchanger.

  DESCRIPTION OF SYMBOLS 21 ... Raw material supply part, 22 ... Hydrogen supply part, 23 ... Control part, 24 ... Heating part, 31 ... Reaction container, 32 ... Catalyst layer, 150 ... Dehydrogenation system.

Claims (6)

A reaction vessel that circulates a raw material containing organic hydride, and a dehydrogenation reactor that is disposed in the reaction vessel and that converts the organic hydride into hydrogen and a dehydrogenated product by a dehydrogenation reaction. When,
A raw material supply unit for supplying the raw material to the dehydrogenation reactor;
A hydrogen supply unit for supplying a hydrogen-containing gas containing hydrogen to the dehydrogenation reactor;
A heating unit for supplying heat to the dehydrogenation reactor;
A control unit,
The controller is
When the supply of the raw material to the dehydrogenation reactor by the raw material supply unit is stopped,
With the hydrogen supply unit and the atmosphere of the hydrogen-containing gas in the reaction vessel, heat is supplied to the dehydrogenation reactor by the heating unit,
A dehydrogenation system in which the system is in a standby state while maintaining a condition in which a hydrogenation reaction rate is higher than a dehydrogenation reaction rate as a reaction condition of the dehydrogenation reactor. The controller is
Of the reaction region determined by the relationship between the reaction temperature and reaction pressure of the dehydrogenation reactor, the reaction temperature and the reaction pressure are maintained in a reaction region where the equilibrium conversion of the organic hydride is less than 50%. The dehydrogenation system according to claim 1.   The dehydrogenation system according to claim 1, wherein the control unit maintains a reaction temperature of the dehydrogenation reactor at 200 ° C. or less.   The said control part is a dehydrogenation system as described in any one of Claims 1-3 which hold | maintains the reaction pressure of the said dehydrogenation reactor to 0.1 MpaA or more.   The said control part is a dehydrogenation system as described in any one of Claims 1-3 which hold | maintains the reaction pressure of the said dehydrogenation reactor to 0.3 MpaA or more. An operation method of the dehydrogenation system according to any one of claims 1 to 5,
When the supply of the raw material to the dehydrogenation reactor by the raw material supply unit is stopped,
With the hydrogen supply unit and the atmosphere of the hydrogen-containing gas in the reaction vessel, heat is supplied to the dehydrogenation reactor by the heating unit,
A method for operating a dehydrogenation system, wherein a system standby state is maintained while maintaining a condition in which a hydrogenation reaction rate is higher than a dehydrogenation reaction rate as a reaction condition of the dehydrogenation reactor.

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