JP6759026B2 - Hydrogen production equipment - Google Patents

Description

The present invention relates to a hydrogen production apparatus that produces hydrogen from hydrocarbons.

Conventionally, a technique for producing hydrogen by steam reforming a hydrocarbon such as methane has been put into practical use (for example, Patent Document 1).

However, when hydrocarbons are reformed by steam, there is a problem that not only hydrogen but also carbon dioxide is generated. Since carbon dioxide is a factor of global warming, it is required to reduce its emission to the atmosphere.

Therefore, a technique for producing hydrogen by reducing carbon dioxide emissions by thermally decomposing hydrocarbons in the presence of a catalyst has been developed.

Japanese Unexamined Patent Publication No. 2014-136655

However, when hydrocarbons are thermally decomposed, there is a problem that solid carbon generated together with hydrogen is precipitated and the reactor may be clogged. There is also a desire to reduce the thermal energy required for hydrogen production.

In view of such a problem, an object of the present invention is to provide a hydrogen production apparatus capable of reducing the thermal energy required for hydrogen production and preventing the reactor from being clogged.

In order to solve the above problems, the hydrogen production apparatus according to the present invention has a power generation device that converts chemical energy into electric energy, and a hydrocarbon is thermally decomposed by the exhaust heat of the power generation device to generate solid carbon and hydrogen. The first reaction section, the steam supply section that supplies steam to the first reaction section, and the steam supplied by the steam supply section in the first reaction section heated by the exhaust heat of the power generation device. It includes a second reaction unit that produces a liquid organic compound or hydrogen and a liquid organic compound from the synthetic gas produced by the reaction with the solid carbon .

Further, it may be provided with a hydrogen generation unit that generates hydrogen from the liquid organic compound.

In addition, the first reaction section may thermally decompose the hydrocarbon in the presence of a catalyst.

Further, the hydrocarbon contains at least a methane component and a higher-order hydrocarbon component having 2 or more carbon atoms, and the first reaction unit thermally decomposes the higher-order hydrocarbon component having 2 or more carbon atoms. The methane component may be thermally decomposed by using the solid carbon produced as a catalyst.

It is possible to reduce the thermal energy required for hydrogen production and prevent the reactor from clogging.

It is a figure explaining the hydrogen production apparatus which concerns on 1st Embodiment. It is a figure explaining the relationship between the amount of hydrogen production and the amount of supply of methane for pyrolysis. It is a figure explaining the relationship between the amount of heat absorption and the amount of supply of methane for pyrolysis. It is a figure explaining the hydrogen production apparatus which concerns on 2nd Embodiment.

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, materials, other specific numerical values, etc. shown in the embodiment are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are designated by the same reference numerals to omit duplicate description, and elements not directly related to the present invention are not shown. To do.

(First Embodiment: Hydrogen production apparatus 100)
FIG. 1 is a diagram illustrating a hydrogen production apparatus 100 according to the first embodiment. In FIG. 1, the gas flow is indicated by a solid arrow, the electricity flow is indicated by a white arrow, and the heat flow is indicated by a broken line arrow.

As shown in FIG. 1, the hydrogen production apparatus 100 includes a power generation unit 110, a hydrogen production unit 200, and a supply amount control unit 250.

(Power generation unit 110)
The power generation unit 110 includes a steam reforming reaction unit 120 and a power generation device 130. However, the steam reforming reaction unit 120 may be omitted depending on the type of the power generation device 130.

The steam reforming reaction unit 120 is connected to a raw material gas supply pipe 102 connected to a hydrocarbon supply source. Therefore, the hydrocarbon is supplied from the hydrocarbon supply source to the steam reforming reaction unit 120 through the raw material gas supply pipe 102. In this embodiment, methane (CH ₄ ) will be described as an example of the hydrocarbon. Further, a steam supply pipe 104 is connected to the steam reforming reaction unit 120, and steam is supplied through the steam supply pipe 104.

Then, in the steam reforming reaction unit 120, the reaction (steam reforming reaction) represented by the following reaction formula (1) is carried out, and hydrogen (H ₂ ) and carbon monoxide (CO) are generated from methane. Further, if the reaction (shift reaction) represented by the following reaction formula (2) is carried out in the steam reforming reaction unit 120, hydrogen and carbon dioxide (CO ₂ ) are generated from carbon monoxide. When the reactions represented by the following reaction formulas (1) and (2) are carried out, 4 mol of hydrogen and 1 mol of carbon dioxide are produced from 1 mol of methane. However, the equilibrium composition is a mixed gas of methane, hydrogen, carbon monoxide, carbon dioxide, and water vapor.
CH ₄ + H ₂ O → CO + 3H ₂ … Reaction equation (1)
CO + H ₂ O → CO ₂ + H ₂ … Reaction equation (2)
The reformed gas thus generated is supplied to the power generation device 130 through the pipe 122.

The power generator 130 is composed of, for example, a solid oxide fuel cell (SOFC) and converts the reformed gas into electric power and heat. The heat (exhaust heat) generated by the power generation device 130 is transferred to the reactor (here, first reaction units 210a and 210b described later). Further, the off-gas discharged from the power generation device 130 may be completely exhausted to the outside through the pipe 132, or a part of the off-gas may be recycled as a part of the fuel.

(Hydrogen production unit 200)
The hydrogen production unit 200 includes first reaction units 210a and 210b, steam supply units 220a and 220b, and a second reaction unit 230.

The first reaction units 210a and 210b contain catalysts that promote the reaction (pyrolysis reaction) represented by the following reaction formula (3).
CH ₄ → C + 2H ₂ … Reaction equation (3)

A pipe 106 branched from the raw material gas supply pipe 102 is connected to the first reaction unit 210a. Therefore, methane is supplied from the methane supply source to the first reaction unit 210a through the raw material gas supply pipe 102 and the pipe 106. Similarly, a pipe 108 branched from the pipe 106 is connected to the first reaction unit 210b. Therefore, methane is supplied from the methane supply source to the first reaction unit 210b through the raw material gas supply pipes 102, 106, and 108.

As described above, the exhaust heat of the power generation device 130 is transmitted to the first reaction units 210a and 210b. Therefore, in the first reaction units 210a and 210b, the reaction represented by the above reaction formula (3) is carried out, and methane is decomposed into solid carbon (C) and hydrogen. In the present embodiment, the exhaust heat of the power generation device 130 is transmitted so that the first reaction units 210a and 210b are at about 700 ° C. to 800 ° C. As a result, the solid carbon produced in the above reaction formula (3) becomes amorphous. Therefore, the reaction efficiency of the reaction formula (4) described later can be improved. The hydrogen produced in this way is supplied to an external hydrogen utilization facility through the pipes 212a and 212b.

When a catalyst is used for the reaction of the reaction formula (3), solid carbon is deposited on the catalyst when the reaction is carried out, and the function of the catalyst is deteriorated. If solid carbon continues to precipitate even when a catalyst is not used, the first reaction sections 210a and 210b will be blocked. Therefore, the steam supply units 220a and 220b supply water vapor to the first reaction units 210a and 210b, and the first reaction units 210a and 210b carry out the reaction (synthetic gas generation reaction) represented by the following reaction formula (4).
C + 2H ₂ O → CO ₂ + 2H ₂ … Reaction equation (4)

Specifically, the steam supply unit 220a includes a steam supply pipe 222a that connects the steam supply source and the first reaction unit 210a, and a valve 224a provided in the steam supply pipe 222a. Therefore, water vapor is supplied to the first reaction unit 210a through the water vapor supply unit 220a. Similarly, the steam supply unit 220b includes a steam supply pipe 222b that connects the steam supply source and the first reaction unit 210b, and a valve 224b provided in the steam supply pipe 222b. Therefore, water vapor is supplied to the first reaction unit 210b through the water vapor supply unit 220b. Then, by transmitting the exhaust heat of the power generation device 130, the reaction represented by the reaction formula (4) is carried out in the first reaction units 210a and 210b.

Therefore, in the first reaction unit 210a or the first reaction unit 210b, the supply of methane through the pipes 106 and 108 and the supply of water vapor through the steam supply units 220a and 220b are exclusively performed. Further, when methane is supplied to the first reaction unit 210a, water vapor is supplied to the first reaction unit 210b, and when water vapor is supplied to the first reaction unit 210a, the first reaction unit 210b Is supplied with methane. As a result, hydrogen can be continuously produced. Further, when a catalyst is used, the catalyst can be continuously regenerated (solid carbon is removed from the catalyst). As described above, in the first reaction unit 210a and the first reaction unit 210b, since the reaction represented by the reaction formula (3) and the reaction represented by the reaction formula (4) are exclusively performed, one reaction rate is obtained. If is different from the other reaction rate, the slow reaction becomes the bottleneck of the reaction of the whole system. Therefore, in the present embodiment, the reaction rates of the first reaction units 210a and 210b are substantially the same by adjusting the catalyst amount and temperature (heat amount supplied from the power generation device 130) in the first reaction units 210a and 210b. I have to.

On the other hand, the mixed gas of carbon dioxide and hydrogen generated by carrying out the reaction represented by the reaction formula (4) is supplied to the second reaction unit 230 through the pipes 216a and 216b.

The second reaction unit 230 contains a catalyst that promotes the reaction represented by the following reaction formula (5). 1 mol of hydrogen is produced by the reaction represented by the following reaction formula (5).
CO ₂ + 2H ₂ → CH ₂ O ₂ + H ₂ … Reaction equation (5)

Therefore, when a mixed gas of carbon dioxide and hydrogen (carbon dioxide: hydrogen = 1: 2) is supplied to the second reaction unit 230, the reaction represented by the above reaction formula (5) is carried out, and formic acid (CH ₂ O ₂ ) is carried out. ) And hydrogen will be generated. A tank (not shown) filled with water (liquid) is arranged in the second reaction unit 230, and CO ₂ and H ₂ described on the left side of the reaction formula (5) are introduced into the tank. To. In the tank, CO ₂ and H ₂ react in water to produce an aqueous solution of formic acid. Then, the hydrogen separated from the aqueous solution is supplied to the external hydrogen utilization facility through the pipe 232.

Further, the second reaction unit 230 does not have to include the tank. In this case, the formic acid (gas) generated by the reaction formula (5) may be made into a liquid by cooling it to its boiling point (100.8 ° C.) or lower. As a result, formic acid and hydrogen can be easily separated. Then, the separated hydrogen is supplied to the external hydrogen utilization facility through the pipe 232. On the other hand, the separated formic acid is sent to the outside through the pipe 234. By fixing the carbon of methane as formic acid, carbon dioxide emissions are reduced, and it is also a raw material for C1 chemical processes (synthetic chemical processes of organic compounds made from compounds with 1 carbon number) such as chemical products and polymer production. Can be used as.

(Supply amount control unit 250)
The supply amount control unit 250 is composed of a semiconductor integrated circuit including a CPU (Central Processing Unit). The supply amount control unit 250 reads a program, parameters, etc. for operating the CPU itself from the ROM, and cooperates with the RAM as a work area and other electronic circuits to cooperate with the valves 102a, 104a, 106a, 108a, 214a, The opening degree of 214b, 218a, 218b, 224a, and 224b is controlled. The supply amount control unit 250 controls the opening degree of the valves 102a, 106a, 108a based on the methane supply amount and the heat absorption amount described later. The simulation results of the amount of methane supplied and the amount of heat absorbed will be described below.

(simulation result)
Methane for thermal decomposition is based on the case where methane (fuel) is supplied to the fuel electrode of the power generation device 130 at 1 mol / sec and methane is not supplied to the first reaction units 210a and 210b (thermal decomposition rate of methane = 0). The amount of hydrogen produced (hereinafter referred to as "the amount of hydrogen produced") and the amount of heat absorbed when the amount of methane supplied (hereinafter referred to as "the amount of methane for thermal decomposition") was changed were simulated. At this time, it was assumed that the power generation efficiency of the electric power output by the power generation device 130 was 50%. Further, the amount of steam supplied from the steam supply pipe 104 to the power generation device 130 was adjusted by adjusting the opening degree of the valve 104a provided in the steam supply pipe 104 so that the S / C (steam / methane) was 3. It is also assumed here that the entire amount of pyrolysis methane is pyrolyzed into hydrogen and solid carbon.

FIG. 2 is a diagram for explaining the relationship between the amount of hydrogen produced and the amount of methane supplied for thermal decomposition. Here, since only the hydrogen produced by the reaction formula (3) was considered, the proportional coefficient was 2. If hydrogen generated by the reaction formula (5) is included, the proportional coefficient becomes 3. As shown in FIG. 2, the amount of hydrogen produced increases in proportion to the amount of methane supplied for thermal decomposition. However, it is expected that the amount of heat required for thermal decomposition will also increase.

FIG. 3 is a diagram for explaining the relationship between the amount of heat absorbed and the amount of methane supplied for thermal decomposition. In FIG. 3, the solid line shows the relationship between the amount of heat absorbed by the first reaction units 210a and 210b that carry out the thermal decomposition reaction represented by the above reaction formula (3) and the amount of methane supplied for thermal decomposition, and the broken line indicates the above. The sum of the amount of heat absorption with the first reaction units 210a and 210b for carrying out the thermal decomposition reaction represented by the reaction formula (3) and the synthetic gas generation reaction shown in the above reaction formula (4), and the supply amount of methane for thermal decomposition. Show the relationship.

As the supply amount of pyrolysis methane increases, the pyrolysis reaction represented by the above reaction formula (3) increases. Therefore, as shown by the solid line in FIG. 3, the amount of heat absorption of the first reaction units 210a and 210b for carrying out the thermal decomposition reaction represented by the above reaction formula (3) increases as the supply amount of thermal decomposition methane increases.

When the heat absorption amount of the reaction formula (4) is added, the sum of the heat absorption amounts increases as the supply amount of pyrolysis methane increases, as shown by the broken line in FIG. For example, when exhaust heat of about 400 kW can be obtained by a power generation device 130 using 1 mol / sec of methane as fuel, the first reaction units 210a and 210b are used until the supply amount of pyrolysis methane is about 2 mol / sec. The heat for carrying out the pyrolysis reaction and the heat for carrying out the syngas generation reaction can be supplied by the power generation device 130. However, when the supply amount of methane for pyrolysis is about 2 mol / sec or more, the power generation efficiency of the power generation device 130 is lowered to increase the amount of exhaust heat, or another heat source is used when carrying out the syngas generation reaction. I found that I needed to use it.

Therefore, the supply amount control unit 250 determines the supply amount of pyrolysis methane based on the exhaust heat capacity of the power generation device 130 and the available external heat amount. Then, the supply amount control unit 250 controls the opening degree of the valves 102a, 106a, 108a based on the determined supply amount of the thermal decomposition methane.

The supply amount control unit 250 closes the valve 108a when the valve 106a is opened. Further, the supply amount control unit 250 closes the valves 218a and 224a and opens the valve 214a. The supply amount control unit 250 closes the valve 214b and opens the valves 218b and 224b. As a result, while the first reaction unit 210a is carrying out the thermal decomposition reaction shown in the reaction formula (3), the first reaction unit 210b is allowed to carry out the reaction shown in the reaction formula (4). That is, when the first reaction unit 210a thermally decomposes the hydrocarbon to generate hydrogen and solid carbon, the first reaction unit 210b reacts the solid carbon with water vapor to generate a synthetic gas. Will be done.

On the other hand, the supply amount control unit 250 closes the valve 106a when the valve 108a is opened. Further, the supply amount control unit 250 closes the valve 214a and opens the valves 218a and 224a. The supply amount control unit 250 closes the valves 218b and 224b and opens the valve 214b. As a result, while the first reaction unit 210a is carrying out the reaction represented by the reaction formula (4), the first reaction unit 210b is allowed to carry out the thermal decomposition reaction shown in the reaction formula (3). That is, when the first reaction unit 210a reacts solid carbon with water vapor to generate a synthetic gas, the first reaction unit 210b thermally decomposes the hydrocarbon to generate hydrogen and solid carbon. Will be done.

As described above, according to the hydrogen production apparatus 100 according to the present embodiment, since the first reaction units 210a and 210b can produce hydrogen by the exhaust heat of the power generation apparatus 130, the thermal energy (cost) required for hydrogen production is required. ) Can be reduced.

Further, since the synthetic gas generation reaction is carried out in the first reaction units 210a and 210b, the catalyst contained in the first reaction units 210a and 210b can be regenerated (solid carbon is removed from the catalyst). This makes it possible to prevent deterioration of the catalytic function due to precipitation of solid carbon and clogging of the reactor.

Further, with the configuration including the second reaction unit 230, a liquid organic compound can be produced, and carbon (atom) can be separated as a liquid organic compound. Therefore, carbon (atoms) can be easily recovered.

(Second embodiment: hydrogen production apparatus 300)
In the first embodiment, the configuration in which the liquid organic compound produced by the second reaction unit 230 is sent to the outside has been described as an example. However, hydrogen can also be generated from the liquid organic compound material produced by the second reaction unit 230.

FIG. 4 is a diagram for explaining the hydrogen production apparatus 300 according to the second embodiment. As shown in FIG. 4, the hydrogen production apparatus 300 includes a power generation unit 110, a hydrogen production unit 310, and a supply amount control unit 250. The same reference numerals are given to the configurations substantially the same as those of the first embodiment, and the description thereof will be omitted.

The hydrogen production unit 310 includes first reaction units 210a and 210b, steam supply units 220a and 220b, a second reaction unit 230, and a hydrogen generation unit 320.

A pipe 234 is connected to the hydrogen generation unit 320, and a liquid organic compound (formic acid) is supplied through the pipe 234. The hydrogen generating section 320 includes a closed container for accommodating formic acid, a heating section for heating the closed container to a predetermined temperature (for example, about 80 ° C.), and a cooling section for cooling the closed container to a predetermined temperature (about −50 ° C.) after heating. It is composed including and. As a result, the reaction represented by the following reaction formula (6) can be carried out, and hydrogen can be further produced. In addition, carbon dioxide can be recovered as a liquid due to the configuration including the cooling unit.
CH ₂ O ₂ → H ₂ + CO ₂ … Reaction equation (6)

The hydrogen generated by the hydrogen generation unit 320 in this way is supplied to the external hydrogen utilization facility through the pipe 322. Further, the carbon dioxide (liquid) separated and recovered by the hydrogen generating unit 320 will be supplied to an external processing facility through the pipe 324.

Although the preferred embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such an embodiment. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the claims, which naturally belong to the technical scope of the present invention. Understood.

For example, in the above embodiment, methane has been described as an example of a hydrocarbon that is thermally decomposed by the first reaction units 210a and 210b. However, the type of hydrocarbon is not limited. For example, it may be a mixture containing at least a methane component such as natural gas or city gas and a higher-order hydrocarbon component having C2 or more (carbon number of 2 or more). When city gas is used as the hydrocarbon that is thermally decomposed by the first reaction units 210a and 210b, it is not necessary to house the catalyst in the first reaction units 210a and 210b. In this case, in the first reaction units 210a and 210b, the higher-order hydrocarbon component of C2 or higher in the city gas is first thermally decomposed, and the methane component may be decomposed by utilizing the catalytic action of the precipitated solid carbon. it can.

Further, in the above embodiment, the case where the power generation device is SOFC has been described as an example. However, the power generation device is not limited in configuration as long as it can convert chemical energy into electrical energy. For example, the power generation device may be composed of a distributed power source such as a fuel cell other than SOFC (for example, molten carbonate fuel cell (MCFC)), or may be a large-scale thermal power generation such as an engine or a gas turbine. .. Further, it may be a power generation device of a plurality of hybrids of a fuel cell, an engine, and a gas turbine, or a power generation device of a hybrid of any one or more of these and another power generation device.

Further, in the above embodiment, the configuration in which the power generation device converts hydrocarbons into electric energy has been described as an example. However, the power generation device is not limited to hydrocarbons, and may use organic compounds as fuel.

Further, in the above embodiment, the configuration in which the hydrogen generated by the first reaction units 210a and 210b, the second reaction unit 230, and the hydrogen generation unit 320 is sent to the outside has been described as an example. However, hydrogen generated by any one or more of the first reaction units 210a and 210b, the second reaction unit 230, and the hydrogen generation unit 320 may be supplied to the fuel electrode of the power generation device 130. As a result, the carbon dioxide emission factor of the power generation device 130 can be reduced.

Further, in the above embodiment, the configuration in which the second reaction unit 230 produces formic acid has been described as an example. However, the second reaction unit 230 can also produce a liquid organic compound other than formic acid. For example, methanol can be produced as a liquid organic compound. In this case, the supply amount control unit 250 controls the amount of water vapor supplied by the water vapor supply units 220a and 220b to the first reaction units 210a and 210b, and the ratio of carbon monoxide produced to hydrogen is 1: 2. The reactions shown in the following reaction formulas (7) and (8) are carried out so as to be. Then, the reaction represented by the following reaction formula (9) is carried out in the second reaction unit 230 to produce methanol (CH ₃ OH).
C + H ₂ O → CO + H ₂ … Reaction equation (7)
CO + H ₂ O → CO ₂ + H ₂ … Reaction equation (8)
CO + 2H ₂ → CH ₃ OH (liquid)… Reaction equation (9)

When the liquid organic compound is methanol, the hydrogen generating unit 320 is preferably a device for steam reforming methanol.

Further, a removal mechanism for removing solid carbon from the first reaction units 210a and 210b may be provided. The removal mechanism includes, for example, a vibrating device for vibrating the catalyst and a sieve for separating the catalyst and solid carbon. With the configuration provided with the removal mechanism, the reaction represented by the reaction formula (4) can be reduced, and the energy consumption (calorific value) can be reduced.

The present invention can be used in a hydrogen production apparatus that produces hydrogen from hydrocarbons.

100, 300 Hydrogen production equipment 130 Power generation equipment 210a, 210b First reaction unit 220a, 220b Steam supply unit 230 Second reaction unit 320 Hydrogen generation unit

Claims (4)

A power generator that converts chemical energy into electrical energy,
A first reaction unit that thermally decomposes hydrocarbons by the exhaust heat of the power generation device to generate solid carbon and hydrogen, and
A steam supply unit that supplies steam to the first reaction unit and
In the first reaction unit heated by the exhaust heat of the power generation device, a liquid organic compound or a liquid organic compound or a liquid organic compound or a synthetic gas generated by the reaction of the water vapor supplied by the water vapor supply unit with the solid carbon is used. A second reaction unit that produces hydrogen and liquid organic compounds,
Hydrogen production equipment equipped with. The hydrogen production apparatus according to claim 1 , further comprising a hydrogen generating unit that generates hydrogen from the liquid organic compound. The hydrogen production apparatus according to claim 1 or 2 , wherein the first reaction unit thermally decomposes a hydrocarbon in the presence of a catalyst. The hydrocarbon contains at least a methane component and a higher-order hydrocarbon component having 2 or more carbon atoms.
The first reaction unit according to any one of claims 1 to 3 , wherein the methane component is thermally decomposed by using solid carbon produced by thermally decomposing the higher-order hydrocarbon component having 2 or more carbon atoms as a catalyst. The hydrogen production apparatus described.

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