JP2009221057A - Hydrogen production system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrogen production system capable of stably producing hydrogen with high energy efficiency and excellent load followability without supplying heat additionally from the outside. <P>SOLUTION: The hydrogen production system is provided with a hydrogenation apparatus 1, a gas liquid separation apparatus 2, a dehydrogenation apparatus 3 and a power generation apparatus 4, wherein a hydrogen-containing gas and an aromatic hydrocarbon are supplied to the hydrogenation apparatus 1 to hydrogenate the aromatic hydrocarbon, the hydrogenation reaction product flowing out from the outlet of the hydrogenation apparatus is separated into a gas portion and a liquid portion in the gas liquid separation apparatus 2, an aromatic hydrocarbon hydrogenated product in the liquid portion separated in the gas liquid separation apparatus 2 is dehydrogenated in the dehydrogenation apparatus 3 to produce an aromatic hydrocarbon and hydrogen and the gas portion separated in the gas liquid separation apparatus 2 is supplied to the power generation apparatus 4 to generate powder. At least a part of waste heat generated in the hydrogenation apparatus 1 and at least a part of waste heat generated in the power generation apparatus 4 are used for the heat source of the dehydrogenation apparatus 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a hydrogen production system, and more particularly, to a system capable of stably producing hydrogen with high energy efficiency, good load followability, using a mixed gas containing hydrogen and waste heat in the system. Is.

  From gas refineries such as refineries and steelworks and gasifiers for biomass and waste, mixed gas containing hydrogen is generated, but since this mixed gas has low value, it has been used as fuel gas in the past. There were many. In recent years, the use of hydrogen in fuel cells and the like has been actively studied, and a technique for extracting high-purity hydrogen from such a low-value hydrogen-containing gas has been developed. The most common method is PSA (Pressure Swing Adsorption). However, since the hydrogen recovery rate is about 80% at most, a method using a reaction with an aromatic hydrocarbon that can be expected to have a higher recovery rate has attracted attention. Yes.

  For example, in Patent Document 1 below, since hydrogen in coke oven gas (COG) is used to produce cyclohexane from benzene, and other components in the separated COG are methane-rich gas, SNG (synthetic natural gas) It can be used as In Patent Document 2 below, the reaction with benzene is used to adjust the hydrogen concentration in the COG, and the COG having the adjusted hydrogen concentration is steam reformed and used in the production of methanol and DME. Furthermore, Patent Document 3 below shows a method of extracting hydrogen from COG containing a large amount of hetero compounds using a reaction between naphthalene and tetralin. The remaining COG becomes high in calories due to an increase in methane concentration, and fuel It is suitable as a gas. In these methods, it is possible to recover almost all of the hydrogen in the hydrogen-containing gas by appropriately setting the reaction conditions with the aromatic hydrocarbon. It was burned as a gas, used as a substitute for natural gas, and used as a raw material for chemical production, and was not used directly for power generation.

  On the other hand, gas turbines and fuel cells are known as power generation methods using a gas containing hydrogen. However, in the case of a gas turbine that burns and uses a hydrogen-containing gas, it is preferable that the hydrogen content in the gas is low, resulting in high calories, and conversely, in the fuel cell, the content of components other than hydrogen is strictly defined by the type. Some are. For this reason, it is not preferable to use various by-product gases, fuel gases, etc. as they are in gas turbines and fuel cells.

  Further, the hydrogen in the hydrogen-containing gas taken out by the reaction with the aromatic hydrocarbon as described above is then taken out from the hydride and utilized by the dehydrogenation reaction of the hydride of the aromatic hydrocarbon. . At this time, since the dehydrogenation reaction is an endothermic reaction, it is necessary to supply heat from the outside. Then, in order to improve energy efficiency, using the waste heat from the facility installed as a heat source supplied to a dehydrogenation reaction apparatus is examined.

  For example, in Patent Document 4 below, since the hydrogenation reaction of an aromatic hydrocarbon is an exothermic reaction and the dehydrogenation reaction of an aromatic hydrocarbon hydride is an endothermic reaction, a hydrogenation device and a dehydrogenation device are provided. Although a method is disclosed in which the heat generated during the hydrogenation reaction is recovered via a heat medium such as steam or oil and used for the dehydrogenation reaction, there is heat dissipation and heat exchange loss. I had to replenish the heat.

In addition, in a system for supplying hydrogen at a hydrogen station or the like using the dehydrogenation reaction of aromatic hydrocarbon hydrides, various studies have been conducted on how to supply heat necessary for the dehydrogenation reaction. Yes. For example, a method of combusting produced hydrogen and recovered aromatic hydrocarbon (Patent Document 5 below), a method of using waste heat of a combusted turbine (Patent Document 6 below), and a solid oxide fuel that is also provided A method of utilizing waste heat of a battery (SOFC) (the following Patent Document 7) has been proposed. However, the use of aromatic hydrocarbon combustion is not preferable because it involves the generation of CO ₂ , and the use of hydrogen combustion is preferable because the amount of hydrogen originally intended for use in a fuel cell is reduced. In addition, when using waste heat of a combustion turbine or SOFC, there is a possibility that heat must be replenished separately if there is heat dissipation or heat exchange loss. In these methods, since the recovered aromatic hydrocarbons are hydrogenated again in another place where the hydrogenation device is installed, the heat generated in the hydrogenation device except for the complex is Therefore, it could not be said that the dehydrogenation apparatus was sufficiently utilized effectively.

  Furthermore, in the above mixed gas containing hydrogen, the raw material composition of each plant fluctuates with the switching of oil processed at refineries, coal processed at steelworks, and raw materials processed at gasifiers. Although the composition and flow rate of the mixed gas containing hydrogen may change by changing the operating conditions, the response to these changes has not yet been fully studied.

JP-A-62-215540 JP 2005-146147 A JP 2006-143507 A Japanese Patent Laying-Open No. 2005-200254 JP 2004-256326 A JP 2004-197705 A JP 2006-221850 A

  Under such circumstances, the object of the present invention is to use an aromatic hydrocarbon hydrogenation reaction in order to effectively use hydrogen from a hydrogen-containing gas, and to further enhance the dehydrogenation reaction of the produced aromatic hydrocarbon hydride. To provide a hydrogen production system capable of stably producing hydrogen with high energy efficiency, good load followability, without separately supplying heat from the outside when producing purified hydrogen. is there.

  As a result of diligent research to solve the above problems, the present inventors have installed a hydrogenation device, a dehydrogenation device, and a power generation device all at the same site, hydrogenated aromatic hydrocarbons in the hydrogenation device, and hydrogenated The amount of gas remaining after the reaction is used in the power generation device, and at least a part of the waste heat generated in the hydrogenation device and the power generation device is supplied to the dehydrogenation device that needs to supply heat. Is not required to be supplied from an external heat source other than the hydrogenation device and the power generation device, and when the power generation device is a fuel cell including a reformer, the waste heat of the power generation device is removed from the dehydrogenation device and the reformer. It was found that hydrogen can be stably produced even when the composition and flow rate of the hydrogen-containing gas vary, and the present invention has been completed.

That is, the hydrogen production system of the present invention comprises a hydrogenation device, a gas-liquid separation device, a dehydrogenation device, and a power generation device,
Hydrogenating aromatic hydrocarbons by supplying a hydrogen-containing gas and aromatic hydrocarbons to the hydrogenator,
The hydrogenation reaction product flowing out from the outlet of the hydrogenation device is separated into a gas component and a liquid component by the gas-liquid separator,
Aromatic hydrocarbons in the liquid separated by the gas-liquid separator are dehydrogenated by the dehydrogenator to produce aromatic hydrocarbons and hydrogen,
A hydrogen production system for generating power by supplying the gas component separated by the gas-liquid separator to the power generator,
At least a part of the waste heat generated in the hydrogenation device and at least a part of the waste heat generated in the power generation device are used as a heat source of the dehydrogenation device. In the present invention, a part of the waste heat generated in the hydrogenation device and the power generation device may be used as a heat source of the dehydrogenation device or all of it may be used.

  In the hydrogen production system of the present invention, the power generator is preferably a fuel cell equipped with a reformer. Here, as the fuel cell, a solid oxide fuel cell (SOFC) and a molten carbonate fuel cell are preferable.

  In the hydrogen production system of the present invention, the hydrogen-containing gas has a hydrogen concentration of 20 to 80% by volume, a saturated hydrocarbon concentration of 10 to 80% by volume, a sulfur compound concentration of 100 mol ppm or less as a sulfur concentration, and CO 2. It is preferable that the concentration is 100 ppm by volume or less, the chlorine compound concentration is 0.1 mol ppm or less as the chlorine concentration, and the cyanide concentration is 0.1 mol ppm or less as the CN concentration. In this case, it is preferable that hydrogen is used for hydrogenation of the aromatic hydrocarbon until the hydrogen concentration is less than 20% by volume.

  According to the present invention, when high-purity hydrogen is extracted from a hydrogen-containing gas using a chemical reaction between an aromatic hydrocarbon and hydrogen, energy used for combustion and power generation, such as city gas, kerosene, and LPG, is particularly used. Without using the hydrogen-containing gas used as a raw material, hydrogen and other gases such as hydrocarbons can be used to sufficiently supply heat to the dehydrogenation apparatus. Furthermore, since this heat supply only changes the supply balance from the hydrogenation apparatus and the supply from the power generation apparatus even if the composition and flow rate of the hydrogen-containing gas of the raw material fluctuate, there is no need to use additional energy. There is also an advantage.

  Hereinafter, an embodiment of the present invention will be specifically described with reference to FIG. The hydrogen production system shown in FIG. 1 includes an aromatic hydrocarbon hydrogenation device 1, a gas-liquid separation device 2, a dehydrogenation device 3, and a power generation device 4. The hydrogenation apparatus 1 is supplied with a hydrogen-containing gas and aromatic hydrocarbons, and a hydrogenation reaction product flows out from the outlet of the hydrogenation apparatus. The hydrogenation reaction product is an aromatic hydrocarbon hydride generated by a hydrogenation reaction in the hydrogenation apparatus 1, an unreacted aromatic hydrocarbon, and a residual gas after hydrogen is used from a hydrogen-containing gas. And a mixture. Next, the hydrogenation reaction product is separated into a gas component and a liquid component in the gas-liquid separator 2. The gas component separated by the gas-liquid separator 2 is supplied to the power generator 4 and converted into electricity and heat for final use. On the other hand, the liquid component separated by the gas-liquid separation device 2 is supplied to the dehydrogenation device 3, and the aromatic hydrocarbon hydride in the liquid component is dehydrogenated to produce aromatic hydrocarbon and hydrogen. The dehydrogenation reaction product includes an aromatic hydrocarbon that has not been hydrogenated in the hydrogenation apparatus 1, an aromatic hydrocarbon that has been generated by the dehydrogenation reaction, an aromatic hydrocarbon hydride that has not been dehydrogenated, hydrogen And separated into a gas component and a liquid component in another gas-liquid separator 5. Since the gas component separated by the gas-liquid separation device 5 contains hydrogen as a main component, it is further purified by a purification device as it is or used for a fuel cell, a hydrogen engine or the like. On the other hand, since the liquid component separated by the gas-liquid separator 5 is mainly composed of aromatic hydrocarbons, it can be recycled to the hydrogenator 1 to be reused for hydrogenation, raw materials of chemicals, solvents, etc. It can be used for other purposes.

  The hydrogen-containing gas used in the system shown in FIG. 1 includes by-product hydrogen and fuel gas obtained from steelworks, refineries, petrochemical complexes, etc., or by-products generated from biomass gasifiers, waste gasifiers, etc. Hydrogen is mentioned. These hydrogen-containing gases may include hydrocarbons such as methane, ethane, and ethylene, sulfur compounds, carbon monoxide, nitrogen compounds, chlorine compounds, cyanide compounds, etc. in addition to hydrogen, and aromatic hydrocarbons. If there are many substances that become poisonous substances for the catalyst used in the hydrogenation reaction, or substances that hinder the operation of the power generation device 4, these are previously determined using conventional techniques. It is preferable to reduce the concentration to less than that.

  If the hydrogen-containing gas contains a large amount of sulfur compounds, hydrodesulfurization, adsorptive desulfurization, soda washing, amine washing, etc., usually performed at refineries, steelworks, etc., can be performed. It is preferably 100 mol ppm or less, preferably 50 mol ppm or less.

If the hydrogen-containing gas contains a large amount of CO, it may be removed by converting it into CO ₂ by a CO shift reaction or the like, and the CO concentration in the hydrogen-containing gas should be 100 ppm by volume or less, preferably 50 ppm by volume or less. Is preferred.

  Further, when an acid gas such as hydrogen chloride, chlorine, or HCN is contained in the hydrogen-containing gas, it is usually removed by water washing or amine washing. The chlorine compound concentration in the hydrogen-containing gas after removal is preferably 0.1 mol ppm or less as the chlorine concentration, and the cyan compound concentration is preferably 0.1 mol ppm or less as the CN concentration.

  Unsaturated hydrocarbons are simultaneously hydrogenated in the hydrogenation of aromatic hydrocarbons and converted to saturated hydrocarbons, which is not preferable in terms of reaction efficiency, but may be contained in a hydrogen-containing gas.

  The hydrogen-containing gas contains mainly a large amount of hydrogen and hydrocarbons. The hydrogen concentration in the hydrogen-containing gas is preferably in the range of 20 to 80% by volume, and the saturated hydrocarbon concentration is preferably in the range of 10 to 80% by volume. In the case of a high-purity gas having a hydrogen concentration exceeding 80% by volume, the utility value as hydrogen is high, so that it can be directly used as a raw material for producing petrochemical products. On the other hand, when the hydrogen concentration is lower than 20% by volume, it can be used as a raw material for hydrogen production because of its high utility value as a hydrocarbon. The system of the present invention is particularly suitable for effectively extracting hydrogen from a hydrogen-containing gas having a low utility value as both hydrogen and hydrocarbon.

  Aromatic hydrocarbons supplied to the hydrogenation apparatus 1 include benzenes and naphthalenes, but those having substituents are preferable from the viewpoint of safety and ease of handling, and toluene, ethylbenzene, xylene, diethylbenzene. It is preferable to use alkylbenzene such as trimethylbenzene, alkylnaphthalene such as methylnaphthalene, ethylnaphthalene, dimethylnaphthalene and diethylnaphthalene, and mixtures thereof. In addition, paraffins such as hexane and heptane, and naphthenes such as cyclohexane and cyclopentane, which do not affect the aromatic hydrocarbon hydrogenation reaction, are contained in the aromatic hydrocarbon supplied to the hydrogenator 1. May be included.

  The aromatic hydrocarbon hydrogenation apparatus 1 may be a fixed bed, a fluidized bed, or a suspended bed. For example, a commercial process already exists as a process for producing cyclohexane from benzene, and based on the conventional technology, an apparatus that similarly removes the heat generated in the hydrogenation reaction through a heat medium such as water vapor or oil is used. It is preferable to do. This is because if the reaction heat is not removed, there is a risk of coking. The heat accumulated in the heat medium is supplied to the dehydrogenation reactor 3 and used as part of the heat necessary for the dehydrogenation reaction of the aromatic hydrocarbon hydride that is an endothermic reaction.

  The catalyst used for hydrogenation may be a commonly used catalyst and is selected from the group consisting of platinum, palladium, ruthenium, rhodium, iridium, nickel, cobalt, iron, rhenium, vanadium, chromium, tungsten, molybdenum and copper. A metal-supported catalyst in which at least one metal is supported on at least one support selected from the group consisting of activated carbon, zeolite, titania, carbon nanotube, molecular sieve, zirconia, mesoporous silica porous material, alumina and silica. Is used. The metal loading in the metal supported catalyst is preferably 0.001 to 10% by weight, more preferably 0.01 to 5% by weight. When the hydrogen-containing gas contains sulfur compounds or carbon monoxide, it is preferable to select catalysts that are resistant to these, and palladium, nickel-molybdenum, nickel, which are often used as desulfurization / dearomatic catalysts for petroleum refining. -Tungsten or the like is particularly preferred.

  The conditions for the hydrogenation reaction are appropriately selected depending on the composition of the hydrogen-containing gas used and the composition of the aromatic hydrocarbon. The reaction temperature is 50 to 500 ° C., preferably 80 to 350 ° C., and the hydrogen partial pressure is 0.1 to What is necessary is just to carry out on the conditions of 10 Mpa, Preferably it is 0.1-5 Mpa, More preferably, it is 0.3-2 Mpa. In order to control the composition of the gas remaining after the hydrogenation reaction, it is preferable to control the hydrogenation conversion rate according to the flow rate / flow rate of the hydrogen-containing gas and aromatic hydrocarbon, and the reaction temperature. Can be lowered.

  After the hydrogenation, gas and liquid are separated through the gas-liquid separator 2. Here, the operating temperature of the gas-liquid separator 2 is appropriately selected according to the boiling point of the aromatic hydrocarbon to be used and the aromatic hydrocarbon hydride to be generated, and is preferably in the range of 5 to 50 ° C. The range of is more preferable.

  The gas component separated by the gas-liquid separator 2 includes hydrogen reduced from hydrogen-containing gas used for hydrogenation of aromatic hydrocarbons and hydrogenation of unsaturated hydrocarbons, and hydrogenation of unsaturated hydrocarbons. Of saturated hydrocarbons increased by the above, other gas components not used for hydrogenation, vapor of unreacted aromatic hydrocarbons, and aromatic hydrocarbon hydrides (naphthenes) produced by hydrogenation of aromatic hydrocarbons. ) Vapor. Since the gas is supplied to the power generation device 4 such as a solid oxide fuel cell (SOFC) or a molten carbonate fuel cell, the hydrogen concentration is low and the concentration of a substance that hinders operation is low. Is preferred. Therefore, the hydrogen concentration is less than 20 vol%, preferably 10 vol% or less, the sulfur compound concentration is 100 molppm or less as the sulfur concentration, the CO concentration is 100 volppm or less, and the chlorine compound concentration is 0.1 as the chlorine concentration. It is preferable to control the conversion rate of the hydrogenation reaction so that the cyanide concentration is 0.1 mol ppm or less as the CN concentration at mol ppm or less.

  On the other hand, the liquid component separated by the gas-liquid separator 2 includes unreacted aromatic hydrocarbons and aromatic hydrocarbon hydrides (naphthenes) generated by hydrogenation of aromatic hydrocarbons. The hydride of aromatic hydrocarbon contained in the liquid component varies depending on the aromatic hydrocarbon used, for example, alkylcyclohexane such as methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, diethylcyclohexane, trimethylcyclohexane, methyldecalin, ethyldecalin, Alkyl decalins such as dimethyl decalin and diethyl decalin, and mixtures thereof. The liquid component is mainly supplied to the dehydrogenation device 3, but may be recycled to the hydrogenation device 1 as needed, or may be used as a solvent or a raw material for chemicals.

  The gas component separated by the gas-liquid separator 2 is supplied to the power generator 4 and used for power generation. As the power generation device 4, a fuel cell including a reformer is preferable as a power source capable of generating a mixed gas containing hydrogen, hydrocarbons, carbon dioxide, carbon monoxide and the like as a raw material. Examples thereof include an oxide fuel cell (SOFC) and a molten carbonate fuel cell. In addition, it is preferable to provide a desulfurization apparatus and a pre-reformer as needed in the fuel cell incorporating the reformer. When the sulfur concentration in the supplied gas component is 50 mol ppb or more, desulfurization using an adsorbent such as iron oxide, zinc oxide, zeolite, activated carbon, etc., and the sulfur concentration in the gas component supplied to the fuel cell Is preferably 50 mol ppb or less. Further, when the gas component to be supplied contains hydrocarbons of C2 or higher, it is likely to cause coking. Therefore, preliminary reforming is performed so that hydrocarbons of C2 or higher are not supplied to the fuel cell. preferable.

  As the reforming catalyst used in the pre-reformer and the reformer in the fuel cell, a catalyst generally known as a steam reforming catalyst may be used. For example, a metal such as Ni, Ru, Rh, etc. may be alumina, zirconia. A material supported on a carrier such as ceria is used.

  The reforming reaction is preferably performed under the conditions of a reaction temperature of 400 to 900 ° C., a reaction pressure of normal pressure to 3 MPa, a GHSV of 500 to 500,000, and an S / C of 0.5 to 3.

  Electricity generated by SOFC and molten carbonate fuel cells is provided to factories and communities where the equipment is installed, and can be used in homes, buildings, offices, etc., or supplied to electric vehicles.

  The dehydrogenation apparatus 3 is filled with a catalyst, and an aromatic hydrocarbon hydride is supplied to cause a dehydrogenation reaction. The dehydrogenation reactor can take either a method of supplying an aromatic hydrocarbon hydride as a liquid or a method of supplying it as a gas after preheating, and in particular, supplying a gas to a fixed bed reactor. Is preferred.

  The catalyst used for the dehydrogenation reaction is one in which at least one metal selected from the group consisting of platinum, ruthenium, palladium, rhodium, tin, rhenium and germanium is supported on a porous carrier. The porous carrier may be granular or plate-shaped. When a fixed bed filled with a particulate catalyst is used for the dehydrogenation reactor, it is preferable to select an average pore size depending on the type of aromatic hydrocarbon hydride supplied to the reactor. That is, a catalyst having an average pore diameter of 40 to 80 mm is particularly preferred when using one-ring cyclohexanes, and a catalyst having an average pore diameter of 65 to 130 mm is particularly preferred when using two-ring decalins. Preferably, the pore volume having a preferable pore diameter is preferably 50% or more of the total pore volume.

In order to control the ratio of the average pore diameter and the pore volume, Al ₂ O ₃ or SiO ₂ is preferably used as the catalyst support, and each may be used alone or in combination at an appropriate ratio. It doesn't matter. When the aromatic hydrocarbon hydride is a mixture of one ring and two rings, a catalyst having a preferable average pore diameter may be mixed and used depending on the composition.

  The metal loading is preferably 0.001 to 10% by mass, more preferably 0.01 to 5% by mass. If the metal loading is less than 0.001% by mass, a sufficient dehydrogenation reaction cannot be obtained. On the other hand, even if it exceeds 10% by mass, an effect commensurate with the increase in the amount of metal cannot be obtained.

  In the dehydrogenation reaction, in the presence of the dehydrogenation catalyst, LHSV is 0.5 to 4, the reaction temperature is 100 to 450 ° C., preferably 250 to 450 ° C., the reaction pressure is normal pressure to 2 MPa, hydrogen It is carried out by distributing. The hydrogen flow rate is preferably in the range of 0.01 to 10 in terms of hydrogen / aromatic hydrocarbon hydride molar ratio. When hydrogen is circulated and the dehydrogenation reaction is performed, side reactions can be suppressed compared to when hydrogen is not circulated, and not only hydrogen can be produced efficiently, but also the oil recovered after the dehydrogenation reaction is hydrogenated again. Therefore, it is preferable because impurities contained in the reuse as an aromatic hydrocarbon hydride can be reduced. Furthermore, in order to produce hydrogen efficiently, it is preferable to select reaction conditions so that the conversion rate is 90% or more.

  After the dehydrogenation reaction, it is separated into a gas component and a liquid component via the gas-liquid separator 5. Here, the operating temperature of the gas-liquid separator 5 is appropriately selected according to the boiling point of the aromatic hydrocarbon and the hydride of the aromatic hydrocarbon, preferably in the range of 5 to 50 ° C, and in the range of 15 to 35 ° C. Is more preferable.

  The gas component separated by the gas-liquid separator 5 becomes highly purified hydrogen as compared with the hydrogen-containing gas supplied to the hydrogenator 1. Depending on the gas-liquid separation temperature, the gas component may contain aromatic hydrocarbons, aromatic hydrocarbon hydrides, decomposed methane, etc., so it is preferable to further refine and use depending on the use of hydrogen. . As a purification method, a generally used method may be employed. For example, the purification may be performed using a hydrogen separation membrane, an adsorbent, PSA, TSA (Temperature Swing Adsorption), or the like.

  On the other hand, the liquid separated by the gas-liquid separator 5 mainly contains aromatic hydrocarbons, but may contain unreacted aromatic hydrocarbons, decomposed paraffins, and the like. The liquid component is preferably supplied to the hydrogenation apparatus 1 and used again for the reaction with the hydrogen-containing gas. When the flow rate or composition of the hydrogen-containing gas varies and adjustment is required, a part of the liquid may be taken out as a solvent or a chemical raw material.

  Since the dehydrogenation reaction in the dehydrogenation device 3 is an endothermic reaction, it is necessary to supply heat from the outside. Use. When the power generation device 4 is a fuel cell including a reformer, all of the waste heat generated in the hydrogenation device 1 and part of the waste heat generated in the power generation device 4 are used as a heat source for the dehydrogenation device 3. And it is preferable to utilize the remainder of the waste heat which generate | occur | produced in the electric power generating apparatus 4 for the heat source of a reformer. The method of using the waste heat of the power generation device 4 or the hydrogenation device 1 is not particularly limited. For example, as shown in FIG. 2, the dehydrogenation provided with a multi-tubular dehydrogenation reactor is performed on the exhaust gas from the power generation device 4. A method of blowing into the upper part of the device 3 or a method of heating the aromatic hydrocarbon hydride through the heat exchanger 6 using the exhaust gas from the power generation device 4 as shown in FIG. More preferably, as shown in FIG. 4, a system in which the hydrogenation device 1 and the dehydrogenation device 3 are integrated so that heat supply and demand can be efficiently performed is preferable.

  FIG. 4 shows an example of a preferred embodiment of the hydrogen production system of the present invention, which system comprises a composite reactor 7 capable of both hydrogenation and dehydrogenation, and the same hydrogenation and dehydrogenation reactor. Therefore, the reaction heat of hydrogenation can be efficiently supplied to the dehydrogenation reaction. The hydrogen production system shown in FIG. 4 includes SOFC 8 as a power generator, and the waste heat of SOFC 8 is used for heating the raw material mixture for the hydrogenation reaction and the aromatic hydrocarbon hydride via the heat exchanger 9. . In addition, the system includes a hydrogen separation membrane 10 at the outlet of the dehydrogenation reactor portion of the composite reactor 7, and among the dehydrogenation reaction products, hydrogen permeates the hydrogen separation membrane 10 and is taken out of the system. The other components are separated into a gas component and a liquid component via the gas-liquid separator 11. The hydrogen-containing gas inlet is provided in the hydrogenation reactor portion of the composite reactor 7, but may be provided in the SOFC 8 as necessary. The system shown in FIG. 4 further includes heat exchangers 12, 13, and 14. In the heat exchanger 12, heat exchange is performed between the hydrogenation reaction product and its liquid component and the SOFC supply air. In the heat exchanger 13, heat exchange is performed between the hydrogenation reaction raw material mixture and the dehydrogenation reaction product that could not pass through the hydrogen separation membrane. In the heat exchanger 14, the hydrogen-containing gas and the high-purity hydrogen The heat efficiency of the entire system is further improved.

  FIG. 5 is an example of a shell-and-tube type reactor in which hydrogenation reaction and dehydrogenation reaction can be performed in the same reactor, and the reactor is preferably used as the combined reactor 7 in FIG. Can do. Here, the dehydrogenation reaction catalyst is filled on the tube 15 side shown in FIG. 5, and the hydrogenation catalyst is filled on the shell 16 side. At this time, as shown in FIG. 6, if the chimneys 18 having the weep holes 17 shown in FIG. 7 are alternately arranged with the tubes 15, gas-liquid dispersion is improved, and the hydrogenation reaction can be performed efficiently.

  According to the method of the present invention, in a steady state, the hydrogenation device 1, the dehydrogenation device 3, and the power generation device 4 can be operated without supplying another energy from the outside. Further, when the flow rate or composition of the hydrogen-containing gas is changed, the operation can be performed with a good heat balance between the apparatuses.

  As an example, the waste heat of the hydrogenation device 1 is supplied to the dehydrogenation device 3, and the waste heat of the power generation device 4 is supplied to the dehydrogenation device 3, a reformer built in the power generation device 4 and other heat utilization destinations. In this case, the distribution of the use of waste heat when the flow rate of the hydrogen-containing gas supplied to the hydrogenation apparatus 1 fluctuates will be described. First, when the flow rate increases without changing the composition of the hydrogen-containing gas supplied to the hydrogenation apparatus 1, the amount of hydrogen increases, so that the aromatic hydrocarbons supplied to the hydrogenation apparatus 1 in order to efficiently extract hydrogen When the amount of is increased, the heat of reaction increases, and the amount of heat that can be supplied from the hydrogenation device 1 to the adjacent dehydrogenation device 3 gradually increases. However, the aromatic hydrocarbon hydride supplied to the dehydrogenation unit 3 may be supplied after being preheated again after passing through the gas-liquid separator 2, and the amount thereof increases considerably with time. come. For this reason, during the transition period, the dehydrogenation apparatus 3 is supplied with a heat amount equal to or greater than the previous steady state from the hydrogenation apparatus 1. Therefore, by reducing the amount of heat supplied from the power generation device 4 having a plurality of waste heat supply destinations to the dehydrogenation device 3 and increasing the distribution of other supply destinations, the heat is not supplied to the dehydrogenation device 3 excessively. do it.

  On the other hand, after gas-liquid separation, the amount of gas supplied to the power generator 4 increases relatively quickly, and firstly the amount of gas supplied to the reformer built in the power generator 4 increases. However, since it takes time until the amount of the reformed gas supplied from the reformer to the fuel cell in the power generation device 4 increases, the fuel cell that is transiently supplied to the reformer The amount of waste heat is less than the amount of heat required for the reformer. Therefore, the waste heat from the fuel cell may be increased in the amount of heat supplied to the reformer as compared with the previous steady state so that the reforming reaction occurs sufficiently. As described above, regarding the heat supply to the dehydrogenation apparatus 3 in the transition period, the heat supply from the hydrogenation apparatus 1 increases and the heat supply from the fuel cell in the power generation apparatus 4 decreases compared to the previous steady state. To do. In addition, the heat supply from the fuel cell in the power generation device 4 to the reformer increases compared to the previous steady state. Therefore, it is possible to operate with good heat balance between the devices without adding special energy during this period. Eventually, as the amount of reformed gas supplied to the fuel cell increases, the amount of power generated by the fuel cell increases and the waste heat also increases. On the other hand, the liquid flow rate to the dehydrogenation device 3 will eventually increase, and the amount of heat required for the dehydrogenation device 3 to increase the reaction sufficiently increases, so the use of waste heat from the fuel cell can be increased. That's fine. In this way, although it shifts to a new steady state, the heat generated in the hydrogenation device 1 and the heat generated in the power generation device 4 can be effectively utilized without adding special energy during this period.

  On the contrary, when the flow rate is reduced without changing the composition of the hydrogen-containing gas, the amount of hydrogen is reduced. For example, the amount of aromatic hydrocarbons supplied to the hydrogenation device 1 is reduced, thereby generating in the hydrogenation device 1. The amount of heat is gradually reduced. Here, in the dehydrogenation apparatus 3, the flow rate of the liquid is still large and the reaction amount is almost maintained, so that the amount of heat necessary for the dehydrogenation apparatus 3 hardly changes, and therefore the amount of heat generated in the hydrogenation apparatus 1. As a result, the amount of heat supplied from the hydrogenation device 1 to the dehydrogenation device 3 is insufficient compared to the steady state. However, since the amount of residual gas is reduced early, the amount of heat required for reforming is relatively responsively reduced. Therefore, the amount of waste heat supplied to the dehydrogenation device 3 can be increased by adjusting the supply ratio of the waste heat of the fuel cell supplied to the reformer inside the battery and the dehydrogenation device 3. Therefore, the amount of heat supplied from the waste heat of the fuel cell can be compensated for by the amount of heat supplied from the hydrogenation device 1 to the dehydrogenation device 3 being insufficient. Eventually, the amount of reformed gas from the reformer decreases, the amount of power generation gradually decreases, and the amount of waste heat of the fuel cell also decreases. On the other hand, the liquid flow rate to the dehydrogenation device 3 gradually decreases, and the amount of heat necessary for the dehydrogenation reaction also decreases, so that it is possible to operate with good heat balance between the devices.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

A hydrogen production system comprising a hydrogenation device, a gas-liquid separation device, a dehydrogenation device, a heat exchanger, and an SOFC equipped with a desulfurizer and incorporating a reformer was assembled. The hydrogenation device of the system is filled with Ni-Mo catalyst, 50% by volume of hydrogen, 30% by volume of methane, 20% by volume of ethane, the sulfur compound concentration is 3 mol ppm (H ₂ S 5 ppm by volume), chlorine compound Hydrogen-containing gas with a chlorine concentration of less than 0.1 mol ppm (hydrogen chloride concentration of less than 0.1 vol ppm) and a cyanide concentration of CN concentration of less than 0.1 mol ppm (HCN concentration of less than 0.1 vol ppm) When A was supplied at a flow rate of 0.31 Nm 3 / h and toluene was supplied at a flow rate of 226 mL / h and a hydrogenation reaction was carried out at 2 MPa and 260 ° C., 90% of the hydrogen contained in the raw material hydrogen-containing gas A was 90%. % Was used, and the conversion of toluene was 98%. At this time, the reaction heat of the hydrogenation reaction was 424 kJ / h, and this heat of reaction was used for the dehydrogenation reaction. In addition, since there was a 10% heat loss during heat exchange, 381 kJ / h was supplied to the dehydrogenation apparatus.

Next, in the gas-liquid separator of the above system, when the reaction gas is gas-liquid separated at 30 ° C., the composition of the gas component B is 8.9% by volume of hydrogen, 53.4% by volume of methane, and 35.7% by volume of ethane. The sulfur compound concentration is 6 mol ppm (H ₂ S 9 vol ppm) as the sulfur concentration, 1.9 vol% methylcyclohexane, the chlorine compound concentration is less than 0.1 mol ppm (the hydrogen chloride concentration is less than 0.1 vol ppm) ), The cyanide concentration was less than 0.1 mol ppm as the CN concentration (HCN concentration less than 0.1 volume ppm), and the flow rate was 0.17 Nm3 / h. The gas content B is 1141 kJ / mol from the composition. On the other hand, the composition of the liquid B was 98% methylcyclohexane and 2% toluene, and the flow rate was 268 mL / h.

  When the gas component B was supplied to the SOFC with a desulfurizer, a total of 6497 kJ / h of energy was extracted from the SOFC with 75% overall efficiency as electricity and heat. Of this, 1498 kJ / h of heat is used to reform the gas component B, and 126 kJ / h of heat is used as a heat amount that is insufficient for vaporization and dehydrogenation of the component B via a heat exchanger. The / h heat was used to vaporize toluene that was fed into the hydrogenator via a heat exchanger.

  Liquid B was supplied to a dehydrogenation apparatus filled with a Pt catalyst, reacted at 0.3 MPa and 320 ° C., and the reaction gas was gas-liquid separated at 30 ° C. The obtained gas C was 98.1% by volume of hydrogen, 1.9% by volume of toluene, and the flow rate was 0.14 Nm 3 / h, while the liquid C was 100% of toluene.

  The reaction heat required for the dehydrogenation reaction of the liquid B was 424 kJ / h. However, 381 kJ / h supplied after the heat exchange from the hydrogenation reactor and a part of the heat from the power generation device were used for the heat exchange. Heating the minute B was sufficient. If 204 kJ / h used for the dehydrogenation reaction and the vaporization of B and toluene from the power generator side is obtained separately by burning kerosene, a heat dissipation loss of 10% is required, but 6.4 mL / h is required. Is no longer needed. Further, when city gas is used instead of the gas B generated from the hydrogenation device, 0.22 Nm 3 / h is required, but this is not necessary.

  Next, since the flow rate of the hydrogen-containing gas A increased by 10% from the above state, the flow rate of toluene was gradually increased by 10% in order to effectively extract hydrogen. Thereby, the calorific value of the hydrogenation device increased to 466 kJ / h, and the heat supplied to the dehydrogenation device via the heat exchanger also became 420 kJ / h. In addition, the gas component B supplied to the SOFC quickly responded and increased by 10%, so the energy generated in the SOFC increased by 10% to 7143 kJ / h. Of this, 1648 kJ / h of heat was used to reform the increased amount of gas B, and 86 kJ / h of heat was used to vaporize the increased amount of toluene. Since the time required for the liquid B to increase by 10% is longer than the time required for the gas B to increase by 10%, the amount of heat required for the dehydrogenation remains at 424 kJ / h for a while during the transition period. The heat supplied from the SOFC as the amount of heat that is insufficient for the vaporization and dehydrogenation of the liquid B, which has not increased, temporarily decreased from 126 kJ / h before the fluctuation to 82 kJ / h. Thereafter, the amount of liquid B is gradually increased. When the increase is completed, the amount of heat required for the dehydrogenation reaction is 466 kJ / h, and 138 kJ / h of the SOFC energy is insufficient for vaporization of liquid B and the dehydrogenation reaction. It came to be used as a heat quantity. When the variation was completed, the amount of gas C produced increased by 10% and the flow rate became 0.15 Nm3 / h.

An outline flow of an example of a hydrogen production system of the present invention is shown. It is the schematic which shows an example of the method of utilizing the waste heat from an electric power generating apparatus as a heat source of a dehydrogenation apparatus. It is the schematic which shows the other example of the method of utilizing the waste heat from an electric power generating apparatus as a heat source of a dehydrogenation apparatus. It is the schematic which shows the suitable example of the method of utilizing the waste heat from a hydrogenation apparatus and an electric power generating apparatus as a heat source of a dehydrogenation apparatus. It is sectional drawing of an example of a shell & tube type reactor. It is sectional drawing which follows the VI-VI line of FIG. It is a side view of a chimney.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydrogenation device 2, 5, 11 Gas-liquid separation device 3 Dehydrogenation device 4 Power generation device 6, 9, 12, 13, 14 Heat exchanger 7 Combined reactor 8 SOFC
10 Hydrogen separation membrane 15 Tube 16 Shell 17 Weep hole 18 Chimney

Claims (5)

Comprising a hydrogenation device, a gas-liquid separation device, a dehydrogenation device, and a power generation device;
Hydrogenating aromatic hydrocarbons by supplying a hydrogen-containing gas and aromatic hydrocarbons to the hydrogenator,
The hydrogenation reaction product flowing out from the outlet of the hydrogenation device is separated into a gas component and a liquid component by the gas-liquid separator,
Aromatic hydrocarbons in the liquid separated by the gas-liquid separator are dehydrogenated by the dehydrogenator to produce aromatic hydrocarbons and hydrogen,
In the hydrogen production system for generating power by supplying the gas component separated by the gas-liquid separator to the power generator,
A hydrogen production system, wherein at least a part of waste heat generated in the hydrogenation device and at least a part of waste heat generated in the power generation device are used as a heat source of the dehydrogenation device.   The hydrogen generation system according to claim 1, wherein the power generation device is a fuel cell including a reformer.   The hydrogen production system according to claim 2, wherein the fuel cell is a solid oxide fuel cell or a molten carbonate fuel cell.   The hydrogen-containing gas has a hydrogen concentration of 20 to 80 vol%, a saturated hydrocarbon concentration of 10 to 80 vol%, a sulfur compound concentration of 100 mol ppm or less as a sulfur concentration, and a CO concentration of 100 vol ppm or less, The hydrogen production system according to claim 1, wherein the chlorine compound concentration is 0.1 mol ppm or less as a chlorine concentration, and the cyanide concentration is 0.1 mol ppm or less as a CN concentration.   5. The hydrogen production system according to claim 4, wherein the hydrogen-containing gas uses hydrogen for hydrogenation of the aromatic hydrocarbon until the hydrogen concentration becomes less than 20% by volume.

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