JP2015227256A - Hydrogen supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydrogen supply system which allows use of off gas in a dehydrogenation reaction in a dehydrogenation reaction part while suppressing deterioration of a dehydrogenation catalyst.SOLUTION: A hydrogen supply system 100 is provided in a recycle line L7 and hydrogenates toluene (dehydrogenation production) contained in off gas, and the off gas discharged from the upstream of a dehydrogenation reactor 3 as an MCH (raw material) contains a dehydrogenation product having not been removed in a hydrogen purification unit 6. The dehydrogenation product thus contained in the off gas is usable as an MCH by hydrogenation in a hydrogenation unit 20, and the dehydrogenation product can be subjected to the dehydrogenation reaction in the dehydrogenation reactor 3 without deterioration of a dehydrogenation catalyst by hydrogenating the dehydrogenation product in the hydrogenation unit 20 and supplying as a raw material. The configuration allows use of off gas in the dehydrogenation reaction in the dehydrogenation reactor 3 while suppressing the deterioration of the dehydrogenation catalyst.

Description

  The present invention relates to a hydrogen supply system that supplies hydrogen.

  As a conventional hydrogen supply system, for example, one disclosed in Patent Document 1 is known. The hydrogen supply system of Patent Document 1 includes a tank for storing a raw material aromatic hydrocarbon hydride, a dehydrogenation reactor for obtaining hydrogen by dehydrogenating a raw material supplied from the tank, and a reactor. A gas-liquid separator that gas-liquid separates the obtained hydrogen and a hydrogen purifier that purifies the gas-liquid separated hydrogen are provided.

JP 2006-232607 A

  The hydrogen supply system may be provided with a recycle line for refluxing off-gas discharged from the hydrogen purifier to the upstream side of the hydrogen purifier. While the hydrogen concentration of the purified gas purified by the hydrogen purifier is extremely high, the off-gas contains a dehydrogenation product as an impurity. Thus, when the offgas containing a dehydrogenation product is refluxed to the dehydrogenation reactor, the dehydrogenation catalyst may be deteriorated. On the other hand, in some cases, offgas is used as a fuel for a burner or the like without supplying it to the dehydrogenation reactor so as not to deteriorate the dehydrogenation catalyst. Here, instead of using offgas as a fuel such as a burner, it has been required to use the offgas for the dehydrogenation reaction in the dehydrogenation reaction section while suppressing the deterioration of the dehydrogenation catalyst.

  Then, this invention aims at providing the hydrogen supply system which can use offgas for the dehydrogenation reaction in a dehydrogenation reaction part, suppressing deterioration of a dehydrogenation catalyst.

  A hydrogen supply system according to the present invention is a hydrogen supply system that supplies hydrogen, and a dehydrogenation reaction section that obtains a hydrogen-containing gas by dehydrogenating a raw material, and a dehydrogenation product is separated from the hydrogen-containing gas Gas-liquid separation unit, a hydrogen purification unit that removes the dehydrogenated product from the hydrogen-containing gas separated in the gas-liquid separation unit, and obtains a purified gas; and an off-gas discharged from the hydrogen purification unit A recycle line for refluxing to the upstream side, and a hydrogenation unit provided in the recycle line, for hydrogenating the dehydrogenation product contained in the offgas and supplying the raw material to the upstream side of the dehydrogenation reaction unit.

  The hydrogen supply system according to the present invention includes a hydrogenation unit that is provided in the recycle line and hydrogenates the dehydrogenation product contained in the offgas and supplies the dehydrogenation product as a raw material to the upstream side of the dehydrogenation reaction unit. The off-gas discharged from the hydrogen purification unit includes a dehydrogenation product that has not been removed by the hydrogen purification unit. Thus, it becomes possible to use as a raw material by hydrogenating the dehydrogenation product contained in off-gas in a hydrogenation part. Therefore, by dehydrogenating the dehydrogenation product in the hydrogenation unit and supplying it as a raw material upstream of the dehydrogenation reaction unit, the dehydrogenation reaction can be performed in the dehydrogenation reaction unit without degrading the dehydrogenation catalyst. it can. As described above, the off-gas can be used for the dehydrogenation reaction in the dehydrogenation reaction section while suppressing the deterioration of the dehydrogenation catalyst.

  The hydrogen supply system according to the present invention may further include a heat exchange unit that supplies heat of the hydrogen-containing gas supplied from the dehydrogenation reaction unit to the gas-liquid separation unit to the hydrogenation unit. In the gas-liquid separation unit, cooling is performed to separate the dehydrogenated product from the hydrogen-containing gas. Therefore, heat can be effectively utilized by using the heat of the hydrogen-containing gas supplied to the gas-liquid separation unit in the hydrogenation unit.

  According to the present invention, the offgas can be used for the dehydrogenation reaction in the dehydrogenation reaction section while suppressing the deterioration of the dehydrogenation catalyst.

It is a block diagram which shows the structure of the hydrogen supply system which concerns on embodiment of this invention. It is a block diagram which shows the structure of the hydrogen supply system which concerns on a prior art example.

  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 showing the configuration of the hydrogen supply system according to this embodiment. The hydrogen supply system 100 according to the present embodiment uses an organic compound (liquid at normal temperature) as a raw material. In the process of hydrogen purification, the dehydrogenated product (organic compound (liquid at room temperature)) obtained by dehydrogenating the organic compound (liquid at room temperature) as a raw material is removed. Examples of the raw material organic compound include organic hydride. An organic hydride is preferably a hydride obtained by reacting a large amount of hydrogen produced in a refinery with an aromatic hydrocarbon. In addition, the organic hydride is not limited to an aromatic hydrogenated compound, and there is a system of 2-propanol (hydrogen and acetone are generated). 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. In this embodiment, methylcyclohexane (hereinafter referred to as MCH) is used as the organic hydride. In addition, hydrides of aromatic hydrocarbons such as cyclohexane, dimethylcyclohexane, ethylcyclohexane, decalin, methyldecalin, dimethyldecalin, and ethyldecalin can be used as organic hydrides (Note that aromatic compounds have a particularly high hydrogen content. This is a preferred example). 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, the hydrogen supply system 100 according to this embodiment includes an MCH tank 1, a vaporizer 2, a dehydrogenation reactor (dehydrogenation reaction unit) 3, a gas-liquid separator (gas-liquid separation unit) 4, Toluene tank 5, hydrogen purifier (hydrogen purifying section) 6, compressor 7, accumulator 8, dispenser 9, heat source 11, cold heat sources 12, 13, hydrogenation device (hydrogenation section) 20, and heat exchanger (heat (Exchange part) 21 is provided. 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. Line L2 connects vaporizer 2 and dehydrogenation reactor 3. The 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 via the hydrogenator 20. Details of the hydrogenation apparatus 20 will be described later. 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. In the following description, the line L7 will be referred to as “recycle line L7”. 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 through the line L2 together with the off gas supplied from the hydrogen purifier 6 through the recycle 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 always increases 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 L1 and L2. Also good. 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 toluene stored in the toluene tank 5 can be recovered and used.

  The hydrogen purifier 6 removes a dehydrogenation product (toluene in this embodiment) from the hydrogen-containing gas obtained by the dehydrogenation reactor 3 and gas-liquid separated by 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 recycle line L7. The off gas supplied to the recycle line L7 is supplied to the vaporizer 2 via a compressor (not shown), and is supplied to the dehydrogenation reactor 3 via 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 film heated to a predetermined temperature to remove dehydrogenated products, and high-purity hydrogen gas ( Purified gas). 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. Examples of membranes applied to the hydrogen purifier 6 include metal membranes (PbAg, PdCu, Nb, etc.), zeolite membranes, inorganic membranes (silica membrane, carbon membrane, etc.), polymer membranes (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, the toluene contained in the hydrogen-containing gas is removed by adsorbing the adsorbent while maintaining the room temperature, and high-purity hydrogen is obtained. 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 principal part of the hydrogen supply system 100 according to the present embodiment will be described. The hydrogenation device (hydrogenation unit) 20 is provided in the recycle line L7, hydrogenates toluene (dehydrogenation product) contained in the offgas, and is disposed upstream of the dehydrogenation reactor 3 as MCH (raw material). This is a device for supplying to the MCH tank 1. Here, the recycle line L7 includes a line L7a that connects the hydrogen purifier 6 and the hydrogenator 20, and a line L7b that connects the hydrogenator 20 and the vaporizer 2. Further, the hydrogenation device 20 is connected to the MCH tank 1 via a line L10. The hydrogen supply system 100 further includes a heat exchanger (heat exchange unit) 21 that supplies the heat of the hydrogen-containing gas supplied from the dehydrogenation reactor 3 to the gas-liquid separator 4 to the hydrogenation device 20. Yes. The heat exchanger 21 recovers the heat of the hydrogen-containing gas flowing through the line L3 connecting the gas-liquid separator 4 and the dehydrogenation reactor 3, and supplies the heat to the hydrogenation device 20 (or the line L7a).

  With such a configuration, the off-gas containing hydrogen gas and toluene is supplied to the hydrogenation device 20 via the line L7a. The hydrogenation apparatus 20 has a hydrogenation catalyst. Therefore, in the hydrogenation apparatus 20, the hydrogenation reaction of toluene is performed by heating the hydrogenation catalyst and flowing hydrogen gas and toluene. At this time, the heat exchanger 21 supplies the heat of the hydrogen-containing gas flowing through the line L3 to the hydrogenation device 20. Note that the hydrogenation device 20 may be supplied with heat from a heat source (not shown). Thereby, in the hydrogenation apparatus 20, MCH is obtained by hydrogenation reaction of toluene. The hydrogenation device 20 supplies MCH obtained by hydrogenation of toluene to the MCH tank 1 via the line L10. Moreover, the hydrogenation apparatus 20 supplies what was not used for hydrogenation among the hydrogen gas contained in off gas to the vaporizer | carburetor 2 via the line L7b. Specifically, the off-gas includes 50 to 99.5 mol% of hydrogen, 0.2 to 30 mol% of toluene, 0.1 to 15 mol% of MCH, and 0.1 to 10 mol% of other (for example, methane) substances. included. On the other hand, the gas flowing through the line L7b is 5-99.3 mol% hydrogen, 0-15 mol% toluene, 0.3-30 mol% MCH, 0.1-20 mol% other (for example, methane) substances. included. Thus, the concentration of toluene in the gas flowing to the dehydrogenation reactor 3 can be reduced. Further, since the hydrogen gas having a reduced concentration of toluene is supplied to the dehydrogenation reactor 3, deterioration of the dehydrogenation catalyst can be suppressed. As a material for the dehydrogenation catalyst, for example, a catalyst in which platinum is supported on active alumina is employed.

  Here, an example of a specific configuration of the hydrogenation apparatus 20 will be described. In hydrogenation device 20, the specific method of adding hydrogen to unsaturated hydrocarbon (here, toluene which is a dehydrogenation product) is not particularly limited. However, from the viewpoint of low cost and short reaction time, hydrogen may be usually added to the unsaturated hydrocarbon using a catalyst. Examples of such a catalyst include metals such as Ni, Pd, Pt, Rh, Ir, Re, Ru, Mo, W, V, Os, Cr, Co, and Fe, and alloys thereof. As for the metal which comprises a catalyst, and those alloys, 1 type may be individual and 2 or more types may be used by arbitrary ratios and combinations.

  These catalysts are preferably finely divided from the viewpoint of further cost reduction by reducing the amount of catalyst and an increase in reaction surface area. When a finely divided catalyst is used, it may be supported on an arbitrary carrier from the viewpoint of preventing a reduction in surface area due to aggregation of the fine particle catalyst. When the catalyst is supported on the carrier, the method for supporting is not particularly limited, and for example, a coprecipitation method, a thermal decomposition method, an electroless plating method, or the like can be used. The type of carrier is not particularly limited, and for example, in addition to carbon materials such as activated carbon, carbon nanotubes, and graphite, alumina silicate such as silica, alumina, and zeolite can be used. One type of carrier may be used, or two or more types may be used in any ratio and combination.

  The hydrogenation reaction conditions for unsaturated hydrocarbons in the hydrogenator 20 are not particularly limited, and may be set arbitrarily. For example, hydrogen can be added even at a reaction temperature of room temperature (about 25 ° C.), but from the viewpoint of shortening the reaction time, it may be added at a temperature of about 100 ° C. to 400 ° C.

  In addition, although the reaction pressure during the addition reaction is not particularly limited, the pressure during hydrogen addition is 1 to 50 atm (gauge pressure) from the viewpoint of increasing the efficiency of the addition reaction and shortening the reaction time. That is, it may be 0.1 MPa or more and 5 MPa or less). Therefore, a pressure regulator may be provided between the hydrogen purifier 6 and the hydrogenation device 20 in order to increase the pressure during hydrogen addition.

  Next, operations and effects of the hydrogen supply system 100 according to the present embodiment will be described.

  First, a conventional hydrogen supply system 50 will be described with reference to FIG. The hydrogen supply system 50 does not include the hydrogenation device 20 on the recycle line L7 unlike the hydrogen supply system 100 according to the present embodiment. While the hydrogen concentration of the purified gas purified by the hydrogen purifier 6 is extremely high, toluene (dehydrogenation product) is contained in the off gas as an impurity. Thus, when the offgas containing toluene is refluxed to the dehydrogenation reactor 3, the dehydrogenation catalyst may be deteriorated. The upstream portion of the dehydrogenation reactor 3 has a smaller amount of hydrogen present than the downstream portion. Therefore, especially when toluene contained in the offgas is supplied to the upstream portion of the dehydrogenation reactor 3, the dehydrogenation catalyst deteriorates. On the other hand, the off-gas may be used as a fuel such as a burner without being supplied to the dehydrogenation reactor 3 so as not to deteriorate the dehydrogenation catalyst. Here, it has been demanded that the offgas be used for the dehydrogenation reaction in the dehydrogenation reactor 3 while suppressing the deterioration of the dehydrogenation catalyst, instead of using the offgas as a fuel such as a burner.

  Therefore, the hydrogen supply system 100 according to the present embodiment is provided in the recycle line L7, hydrogenates toluene (dehydrogenation product) contained in the offgas, and discharges it from the upstream portion of the dehydrogenation reactor 3 as MCH (raw material). The off gas to be contained contains toluene that has not been removed by the hydrogen purifier 6. Thus, it becomes possible to use as MCH by hydrogenating the toluene contained in off-gas by the hydrogenation apparatus 20. Therefore, dehydrogenation can be performed in the dehydrogenation reactor 3 without degrading the dehydrogenation catalyst by hydrogenating toluene with the hydrogenation apparatus 20 and supplying it as MCH. As described above, the off-gas can be used for the dehydrogenation reaction in the dehydrogenation reactor 3 while suppressing the deterioration of the dehydrogenation catalyst.

  The hydrogen supply system 100 according to this embodiment further includes a heat exchanger 21 that supplies the heat of the hydrogen-containing gas supplied from the dehydrogenation reactor 3 to the gas-liquid separator 4 to the hydrogenation device 20. The gas-liquid separator 4 is cooled to separate the dehydrogenated product from the hydrogen-containing gas. Therefore, heat can be effectively used by using the heat of the hydrogen-containing gas supplied to the gas-liquid separator 4 in the hydrogenation apparatus 20. Further, the hydrogen-containing gas discharged from the dehydrogenation reactor 3 is not so high temperature (for example, 250 to 350 ° C.), but the temperature when the hydrogenation device 20 is heated to perform hydrogenation is not high temperature (for example, 100). Therefore, even the heat of the hydrogen-containing gas at the location can be sufficiently effectively used in the hydrogenation apparatus 20.

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

  For example, the hydrogen supply system may not include the heat exchanger 21 as shown in FIG. Alternatively, heat may be recovered from another position in the hydrogen supply system and supplied to the hydrogenation apparatus 20.

  DESCRIPTION OF SYMBOLS 1 ... MCH tank, 2 ... Vaporizer, 3 ... Dehydrogenation reactor (dehydrogenation reaction part), 4 ... Gas-liquid separator (gas-liquid separation part), 5 ... Toluene tank, 6 ... Hydrogen purifier (hydrogen purification part) ), 7 ... Compressor, 8 ... Pressure accumulator, 9 ... Dispenser, 11 ... Heat source, 12, 13 ... Cold source, 20 ... Hydrogenation device (hydrogenation part), 21 ... Heat exchanger (heat exchange part), 100 ... Hydrogen supply system.

Claims (2)

A hydrogen supply system for supplying hydrogen,
A dehydrogenation reaction section for obtaining a hydrogen-containing gas by dehydrogenating the raw material;
A gas-liquid separator that separates the dehydrogenated product from the hydrogen-containing gas;
A hydrogen purification unit that removes the dehydrogenation product from the hydrogen-containing gas separated by the gas-liquid separation unit to obtain a purified gas;
A recycle line for refluxing off-gas discharged from the hydrogen purification section upstream of the hydrogen purification section;
A hydrogen supply system, comprising: a hydrogenation unit that is provided in the recycle line and that hydrogenates the dehydrogenation product contained in the off-gas and supplies the dehydrogenation product upstream to the dehydrogenation reaction unit as the raw material.   The hydrogen supply system according to claim 1, further comprising a heat exchange unit that supplies heat of the hydrogen-containing gas supplied from the dehydrogenation reaction unit to the gas-liquid separation unit to the hydrogenation unit.

Images