WO2001004046A1

WO2001004046A1 - Method for electric power generation using fuel cell and electric power generation system using fuel cell

Info

Publication number: WO2001004046A1
Application number: PCT/JP2000/004700
Authority: WO
Inventors: Qingquan Su; Kazuo Kinoshita; Noboru Makita; Masao Murai; Masato Nishiwaki
Original assignee: Ebara Corporation
Priority date: 1999-07-13
Filing date: 2000-07-13
Publication date: 2001-01-18
Also published as: AU5853500A

Abstract

A process for producing hydrogen from a treated gas which is obtained by subjecting a combustible material to methane fermentation to generate a gas, and treating the gas in a reforming step (2) and a modifying step (3), characterized in that the gas treated in a reforming step (2) and a modifying step (3) is subjected to a step (5) of absorbing carbon dioxide and an amine, and then a methanation step (6), or in that the gas treated in steps (2) and (3) is subjected to, in place of the methanation step (6), a hydrogen purification step of separating carbon monoxide, carbon dioxide, methane and nitrogen by adsorption. The hydrogen produced by the above process can be suitably used for a fuel cell, in particular, a solid polymer type fuel cell.

Description

Description Fuel cell power generation method and fuel cell power generation system Technical field

The present invention relates to a technology for recovering the chemical energy of an organic substance in the form of hydrogen gas, and to an energy conversion technique for converting the energy into electric energy with high efficiency. A system for producing hydrogen gas or hydrogen-containing gas from the digested gas obtained by methane fermentation of first-class organic waste, and supplying the produced hydrogen gas or hydrogen-containing gas to a fuel tank to generate electricity It relates to a power generation system. Here, the organic waste includes wastewater from food production, livestock wastewater, and excess sludge generated in sewage treatment plants. -Background technology

In recent years, with increasing awareness of environmental protection, attempts have been made to convert digestive gas or biogas obtained by methane fermentation of organic waste into hydrogen-containing gas to generate electricity using a fuel cell. For example, a digestive gas is reformed to produce a hydrogen-containing gas having a hydrogen content of 70 to 80%, and this is used as a fuel gas at the anode of the fuel cell, and air is used as an oxidant gas at the fuel cell. There is known a technology for generating electricity by supplying power to each power source. Here, the heat source for the reforming process is provided by the anode off gas and the combustion heat generated by burning the power source off gas or air in the combustor.

However, in the above-mentioned conventional technology, the fuel cell system has a low hydrogen content, so that the fuel cell system is complicated and the efficiency is low. Has a problem such as low power generation utilization rate of hydrogen. Disclosure of the invention

In view of the above-mentioned circumstances, the present invention provides a fuel cell from a digestion gas generated by methane fermentation of an organic matter, and particularly, a hydrogen gas or a hydrogen-containing gas suitable for a polymer electrolyte fuel cell to produce a fuel cell. It is an object of the present invention to provide a fuel cell power generation method and a fuel cell power generation system which supply the fuel cell with high efficiency and low environmental load.

In order to solve the above-mentioned problems, the present inventors have conducted intensive studies and as a result, have found that organic materials shown in FIGS. 1 and 2, FIGS. 3 and 4, FIGS. 5 and 6, and FIGS. 10 and 11. A hydrogen production system that efficiently produces high-quality hydrogen gas or hydrogen-containing gas suitable for fuel cells using digestive gas generated by tan fermentation, and a fuel cell that uses the produced hydrogen gas or hydrogen-containing gas. The present invention has been completed, which provides a fuel cell power generation method and a fuel cell power generation system that generate power. That is, the first embodiment of the present invention shown in FIG. 1 and FIG. 2 includes a methane fermentation step in which organic matter is methane fermented, and a gas treatment in which the digestion gas generated in the methane fermentation step is reformed to produce hydrogen gas. This is a fuel cell power generation method based on main fermentation of organic matter, comprising a process and a fuel cell power generation process. The gas treatment step includes a gas pretreatment step, a reforming step, a metamorphosis step, a carbon dioxide water absorption step and / or a carbon dioxide amine absorption step, and a meshing step.

More specifically, the digestive gas obtained in the methane fermentation step is adsorbed and / or absorbed and removed in a gas pretreatment step in the presence of acidic gases such as hydrogen sulfide and trace amounts of hydrogen chloride. Next, in the reforming step, methane in the pretreated gas is reformed into hydrogen and carbon monoxide by a catalytic reaction with steam. Where the digestive gas or The fuel burns in the combustor using a part of the pre-processed gas as fuel, and the reforming heat is supplied and the reaction temperature is maintained by the obtained combustion heat. Then, in the shift process, carbon monoxide in the reformed gas is converted into hydrogen gas and carbon dioxide by a catalytic reaction with steam. Next, in the carbon dioxide water absorption step, the carbon dioxide in the converted gas is brought into contact with water or an alkaline solution to be absorbed and separated. Next, the remaining carbon dioxide is brought into contact with an amine absorbing solution in the carbon dioxide amine absorbing step to be absorbed and separated. Here, the carbon dioxide water absorption step can be omitted, and carbon dioxide can be absorbed and separated only by the carbon dioxide amine absorption step. Next, the decarbonated gas obtained in the carbon dioxide amine absorption step is led to a metalation step, and carbon monoxide and carbon dioxide remaining in the gas are removed by a methanation reaction with hydrogen. . Then, the post-meta- nization gas is supplied as fuel gas, and the oxygen-containing gas is supplied as oxidant gas to the anode and power source of the fuel cell stack in the fuel cell power generation process to generate power. In addition, the anodic off-gas discharged from the fuel cell process is returned to the reforming process to circulate the hydrogen in the anodic off-gas and reform methane gas again for power generation.

Further, the power source off-gas discharged from the fuel cell sock can be sent to a reforming step and used as a combustion aid.

In addition, the second embodiment of the present invention shown in FIGS. 3 and 4 and FIGS. 5 and 6 includes a methane fermentation step of methane fermenting organic matter, and reforming a digestion gas generated in the methane fermentation step. This is a method for producing hydrogen by the methane fermentation of organic materials, which comprises a gas treatment step of producing hydrogen gas by using methane. The gas treatment step includes a gas pretreatment step, a reforming step, a metamorphosis step, a carbon dioxide water absorption step and / or a carbon dioxide amine absorption step, a meta- nation step, and a hydrogen purification step. That is, the digestive gas obtained in the main fermentation step is subjected to a gas pretreatment step to adsorb and / or absorb acidic gases such as hydrogen sulfide and a trace amount of hydrogen chloride. Next, in the reforming step, methane in the pretreated gas is reformed into hydrogen and carbon monoxide by a catalytic reaction with steam. Here, a part of the digestion gas or the gas after desulfurization is burned in a combustor as a fuel, and reforming reaction heat is supplied and the reaction temperature is maintained by the obtained combustion heat. Then, in the shift process, carbon monoxide in the reformed gas is converted to hydrogen gas and carbon dioxide by a catalytic reaction with steam. Next, in the carbon dioxide water absorption step, the carbon dioxide in the converted gas is brought into contact with water or an alkaline solution to absorb and separate. Next, the residual carbon dioxide is brought into contact with the amine absorbing solution in the carbon dioxide amine absorbing step to be absorbed and separated. Here, the carbon dioxide water absorption step may be omitted, and carbon dioxide may be absorbed and separated only by the carbon dioxide amine absorption step. Next, the decarbonated gas obtained in the carbon dioxide amine absorption step is led to a metanalysis step, and carbon monoxide and carbon dioxide remaining in the gas are removed by a methanation reaction with hydrogen. Then, the gas after the metanation is led to a hydrogen purification step. In the second embodiment of the present invention, a hydrogen purification method using a hydrogen storage alloy is used in the hydrogen purification step. That is, in the hydrogen refining process using a hydrogen storage alloy, the water in the gas after desorption is dehumidified, then the methane and nitrogen in the gas are separated, and the hydrogen gas is purified and pressurized. In addition, a part of the hydrogen purification offgas discharged from the hydrogen purification process is discharged outside the system, and the rest is returned to the reforming process for re-reforming. ₍ Also, the hydrogen purification offgas discharged outside the system is burned. The heat of combustion can be used as the heat of reforming in the reforming process or the heat of regeneration of the absorbent in the carbon dioxide amine absorption process.

In addition, as shown in FIGS. 5 and 6, the water purified and pressurized in the hydrogen purification step was used. Fuel gas is used as fuel gas, and oxygen-containing gas is used as oxidant gas to supply electricity to the anode and power source of the fuel cell stack in the fuel cell power generation process. Also, anodic off-gas discharged from the fuel cell power generation process will be supplied to the anode and recycled.

Further, a third embodiment of the present invention shown in FIGS. 10 and 11 includes a methane fermentation step of methane fermenting an organic substance, and producing hydrogen gas by reforming digestive gas generated in the methane fermentation step. This is a method for producing hydrogen by methane fermentation of organic matter comprising a gas treatment step. The gas treatment step includes a gas pretreatment step, a reforming step, a metamorphosis step, a carbon dioxide amine absorption step, and a hydrogen purification step.

That is, the digestive gas obtained in the main fermentation step is subjected to a gas pretreatment step to adsorb and / or absorb acidic gases such as hydrogen sulfide and a trace amount of hydrogen chloride. Next, in the reforming step, methane in the pretreated gas is reformed into hydrogen and carbon monoxide by a catalytic reaction with steam. Here, a part of the digestion gas or the gas after desulfurization is burned in a combustor as a fuel, and reforming reaction heat is supplied and the reaction temperature is maintained by the obtained combustion heat. Then, in the shift process, carbon monoxide in the reformed gas is converted to hydrogen gas and carbon dioxide by a catalytic reaction with steam. Next, in the carbon dioxide amide absorption step, the carbon dioxide in the gas after conversion is brought into contact with the amide absorption liquid to be absorbed and separated. Next, the decarbonated gas obtained in the carbon dioxide amine absorption step is led to a hydrogen purification step. In the third embodiment of the present invention, a hydrogen purification method using a pressure swing adsorption method (PSA method) is used in the hydrogen purification step. That is, the carbon dioxide, carbon monoxide, methane, and nitrogen remaining in the gas after the absorption of carbon dioxide amine are adsorbed and separated by the adsorbent, and the hydrogen gas is purified. A part of the hydrogen purification offgas discharged from the hydrogen purification step is discharged outside the system, and the rest is reformed. To be reformed again. Further, the hydrogen purification offgas discharged to the outside of the system is burned, and the combustion heat can be used as the reforming heat in the reforming step or the absorbent regenerating heat in the carbon dioxide amine absorption step.

Further, as shown in FIG. 11, the hydrogen gas purified in the hydrogen purification step is used as a fuel gas, and the oxygen-containing gas is used as an oxidant gas. Power is supplied to a power source to generate power. Also, anodic off-gas discharged from the fuel cell power generation process will be supplied to the anode and recycled.

In the present invention, a solid polymer fuel cell or a phosphoric acid fuel cell is suitable for the fuel cell used in the fuel cell power generation step.

The digestion gas obtained by methane fermentation of organic matter varies depending on the type of organic matter ゃ main fermentation conditions, but in general, the main components are 60 to 70% methane, 30 to 40% carbon dioxide, and 0% hydrogen. 22%, nitrogen 0 02%, and hydrogen sulfide and hydrogen chloride as trace components in the range of tens to hundreds of ppm.

However, not only is the hydrogen gas supplied to the fuel cell required to have a high hydrogen concentration, but also a carbon monoxide concentration as low as possible. In particular, in the case of a polymer electrolyte fuel cell, 100 ppm of carbon monoxide is required. Below, it is necessary to be preferably 1 O ppm or less, more preferably 1 ppm or less. In addition, since acidic gases, particularly hydrogen sulfide and hydrogen chloride, poison the following various gas absorbents, adsorbents, and various catalysts in addition to the electrode catalyst of the fuel cell, the acid gas is 1 ppm or less, preferably 0.1 ppm or less. It is necessary to remove it to below ppm. In addition, it is necessary to separate gas components such as carbon dioxide in order to increase the hydrogen concentration as much as possible.

In the present invention, a gas pretreatment is performed for acidic gases such as hydrogen sulfide and hydrogen chloride. A process is provided to remove by absorption and / or adsorption. Further, when hydrogen sulfide remains at an allowable concentration or more, an adsorption tower can be provided in the preceding stage of the reforming reactor in the next step to further remove by adsorption.

For carbon monoxide, a conversion step and a metamorphosis step or a hydrogen purification step are provided.First, C 0 is catalyzed with steam in the conversion step to convert hydrogen and carbon dioxide to hydrogen, and the remaining C 0 is further removed in a metanalysis step or a hydrogen purification step.

Carbon dioxide is removed in a carbon dioxide water absorption step and / or a carbon dioxide amine absorption step and a methylation step or a hydrogen purification step. Since methane fermentation usually constitutes a system with other water treatments, such as sewage treatment, large volumes of treated water are typically discharged from the system. Since the treated water has a constant C 0 ₂ absorption capacity, the present invention utilizes the treated water as an absorbing solution of carbon dioxide in the gas after conversion, and more than 60% of the carbon dioxide, preferably Absorb 90% or more. The remaining carbon dioxide is absorbed and separated by the amine absorption solution in the amine absorption step. Here, the carbon dioxide water absorption step can be omitted, and carbon dioxide can be absorbed and separated only by the carbon dioxide amine absorption step. The sensible heat of the high-temperature reformed gas is used for the heat of regeneration of the amide absorption liquid. Further, the exhaust heat from the heat and the cathode off-gas in the fuel cell power generation process described later can be used for the regeneration of the amine-absorbed liquid. Then, the remaining CO ₂ is further removed in a metanalysis process or a hydrogen purification process.

The initial concentration of nitrogen in the hydrogen gas or hydrogen-containing gas supplied to the fuel cell power generation process will be about 0 to several thousand ppm, although it depends on the type of organic matter to be treated. Unless a process for separating nitrogen gas is provided, nitrogen gas will accumulate in the system and must be discharged. g

It is important. In the present invention, hydrogen gas or hydrogen-containing gas to be supplied to the fuel cell power generation process is produced by constantly discharging about 10% of the anode off gas or hydrogen purification off gas in which nitrogen gas is most concentrated to the outside of the system. Maintain the nitrogen concentration within 5%. The anodic off-gas or the hydrogen-purified off-gas discharged to the outside of the system is burned, and the combustion heat can be used as the reforming heat in the reforming process or the absorbent regenerating heat in the carbon dioxide amine absorption process.

In the present invention, the hydrogen consumption rate of the hydrogen-containing gas (ie, the value obtained by dividing the amount of hydrogen in the anode off-gas by the amount of hydrogen in the hydrogen-containing gas) in the fuel cell power generation process during the fuel cell power generation process is set to about 70%. In this case, the ratio of the amount of hydrogen in the exhaust gas to the amount of hydrogen in the hydrogen-containing gas is only about 3%. Therefore, in the present invention, the utilization rate of the produced hydrogen gas in power generation reaches 95% or more.

As compared to the prior art reformed gas, water Motoga scan or hydrogen gas according to the present invention is the hydrogen concentration is very high, since the C 0 ₂ concentration and C 0 concentration is low extremely fuel cell has a long life, High power generation efficiency.

Further, in the present invention, a part of the digestion gas or the pretreated gas is branched and supplied to the reforming process as a fuel gas, so that the amount of the reforming feed gas sent to the reforming process is 20 to 3 as compared with the conventional technology. 0% less. When the reforming feed gas is pressurized and reformed, the boosting power can be reduced by 20 to 30%. Further, since the amount of methane to be reformed is small, the reforming heat to be supplied to the reformer can be reduced by 20 to 30%.

Further, in the present invention, since the pretreated gas having a relatively high calorific value is used as a fuel for supplying heat to the reforming step, the cathode off-gas can be used as an auxiliary combustion agent by a normal combustor. Thus, thermal efficiency can be improved without developing a special combustor. In the conventional technology, an anodic off-gas with a considerably low calorific value is used as fuel, so that acid A special burner had to be developed in order to use a power source off-gas whose elemental concentration was only about half that of air.

The present invention thus increases the energy efficiency of the fuel cell power generation system based on organic fermentation of organic matter, and improves the economic efficiency.

Hereinafter, each step will be described in detail.

A) Methane fermentation process

In the present invention, methane fermentation is performed on organic matter, particularly waste liquid for food production, and organic waste such as surplus sludge generated in biological treatment processes such as livestock wastewater and sewage, and hydrogen gas or hydrogen-containing gas is obtained from the obtained digestion gas. It is manufactured and supplied to the fuel cell to generate electricity, and at the same time, waste heat generated in the fuel cell power generation process is used as a heating source in the main fermentation process.

In the main fermentation process, about 50% of organic matter is decomposed by the digestion of microorganisms under anaerobic conditions with a residence time of 20 to 30 days as shown in the following reaction formula, and methane gas and carbon dioxide gas And so on.

Organic matter-lower fatty acid → CH ₄ + C 0 ₂ (1)

The conditions of the main fermentation step are not particularly limited, but medium-temperature fermentation at a temperature of 30 to 35 ° C is preferable in terms of residence time and efficiency. Here, the exhaust heat from the fuel cell power generation process is used as the heat source for heating and maintaining the temperature of the fermentation liquor.

B) Gas treatment process

1) Gas pretreatment process

In the present invention, a gas pretreatment step is provided for the purpose of removing hydrogen sulfide and hydrogen chloride gas to 1 Ppm or less, preferably to 0.1 ppm or less. <The pretreatment step is constituted by a scrubber and a dry desulfurizer. . Treated water, clean water or water is used as the washing water for the scrubber. For this purpose, an alkaline solution to which 0.05% to 5% of sodium hydroxide is added is still more suitable. When a vigorous soda solution is used as the washing makeup water, the acidic gas is absorbed and removed by the following neutralization reaction.

HS + Na OH → NaH S + H ₂₀ (2)

HC 1 + N a OH → N a C l + H ₂ 0 (3)

Depending on the operating conditions and operation management of the scrubber, a small amount of hydrogen sulfide may remain in the gas after the scrubber. In order to prevent poisoning of the reforming catalyst in the reforming process using hydrogen sulfide, a dry desulfurizer that adsorbs and removes hydrogen sulfide will be installed as advanced desulfurization means. The desulfurizer used in the present invention is obtained by filling a container with a desulfurizing agent. The shape and material of the container to be used are not particularly limited, but the shape is preferably cylindrical, and the material is preferably stainless steel. Further, as the desulfurizing agent to be used, oxides such as iron oxide and zinc oxide, or activated carbon, particularly activated carbon having an alkaline agent carried on the surface are suitable. The desulfurizing agent is preferably in the form of granules, pellets or honeycombs. The desulfurization reaction using iron oxide is described below.

F e 0 + 3 HS → F e S + 3 H ₂ 0 (4)

In the present invention, the absorption desulfurization step using the wet scrubber can be omitted, and the digestion gas can be desulfurized only by the adsorption desulfurization step using the dry desulfurizer.

2) Reforming process

In the present invention, a reforming step is provided, and the following steam reforming reaction (also referred to as steam reforming reaction) is performed in a reforming reactor filled with a shift catalyst.

CH ₄ + H ₂ 0 → CO + 3 H ₂ (5)

As the steam required for the reaction, steam generated by a steam boiler using the sensible heat of the reformed gas as a heat source is added. As the amount of steam to be added, it is preferable that the molar ratio of steam to the main stream (ie, the S / C ratio) is in the range of 2.5 to 3.5. the above Since the metamorphic reaction is an endothermic reaction, raising the reaction temperature lowers the equilibrium concentration of the main body and increases the reaction rate.However, the thermal efficiency decreases, but the reaction temperature is in the range of 700 to 800 ° C. Is desirable. The reaction heat was supplied and the reaction temperature was maintained by burning a part of the digested gas or pretreated gas as fuel, and using the power source off-gas of the fuel cell power generation process as a combustion aid in the combustor. Performed by combustion heat. The type and shape of the catalyst are not limited as long as it promotes the reforming reaction.Nii-, Ru-, Pt-, and Ni_Ru catalysts suitable for the above-mentioned temperature range are available. System, Ru_Pt system or a composite steam reforming catalyst thereof.

In the present invention, since the anode off-gas or the hydrogen purification off-gas is returned to the reforming step, the main material that has been once reformed in the reforming step is circulated to the reforming step and undergoes reforming. When the reforming temperature is lowered, the equilibrium concentration of methane rises, that is, the reforming rate of methane decreases.On the other hand, the reforming efficiency improves, and inexpensive materials can be used for the reformer. There are advantages. According to the present invention, since the problem caused by the lowering of the reforming temperature is solved, the reforming temperature can be improved by lowering the general reforming temperature from 700 to 800 ° C to 600 to 700 ° C. It can improve the thermal efficiency of the quality equipment and, consequently, the fuel cell power generation system as a whole, and reduce manufacturing costs.

3) Metamorphosis process

In the present invention, a shift process is provided, and the shift reaction described below (also called a shift reaction) is performed in a shift reactor filled with a shift catalyst.

CO + H ₂ 0 → C 0 ₂ + H ₂ (6)

The steam component in the reformed gas is used as steam required for the reaction. Since the above transformation reaction is an exothermic reaction, lowering the reaction temperature lowers the equilibrium concentration of carbon monoxide, but conversely lowers the reaction rate. A range of 0 to 250 ° C is desirable. The type and shape of the catalyst are not limited as long as it promotes the shift reaction. Examples of the catalyst suitable for the above temperature range include a Cu—Zn shift catalyst.

4) Carbon dioxide water absorption process

A carbon dioxide water absorption process is provided to remove 60% or more, preferably 90% or more, of carbon dioxide in the gas after selective oxidation using treated water discharged from the main fermentation system or sewage treatment system. The higher the pH of the treated water used, and the lower the temperature, the concentration of dissolved carbonic acid and the concentration of dissolved bicarbonate ions, the higher the ability of the treated water to absorb carbon dioxide. The absorption of carbon dioxide by water consists of two steps: the dissolution of carbon dioxide in water and the transfer of dissolved carbon dioxide to the carbonate group. The absorption reaction involved is described below.

H ₂ 0 + C0 ₂ → H 2 CO 3 (8)

H 2 C 03 + 0 H → HC〇 _3- + H 20 (9)

In the present invention, in order to increase the carbon dioxide absorption capacity, the temperature of the treated water can be lowered by cooling, and the pH can be increased by adding an alkali agent.

5) Carbon dioxide amine absorption process

In the present invention, a carbon dioxide amine absorption step is provided, and the hydrogen-containing gas obtained in the previous step or the anodic gas discharged in the next fuel cell power generation step is led to an absorption tower to be brought into contact with the absorption liquid, thereby obtaining C 2. 0 ₂ absorption separation. As the liquid to be collected, a thermocarbonated realm absorbing solution or an alcohol-absorbing solution is suitable, but in the present invention, an alkanolamine absorbing solution having a strong absorption capacity is still more preferable. Examples of the absorbent include monoethanolamine (MEA), jetanolamine (DEA), and methylgenoaluminamine (MDEA). The adsorption reaction with the alkanolamine absorption solution is shown below. Three

Write.

_{R - NH 2 + H 20 +} C 02 → R - NH 3 HC 03 (1 0) wherein the reaction is advantageously lower the absorption temperature so exothermic reaction, temperature control is relatively easy 1. 2 to 4 0 ° The range of C is preferred. Although the gas pressure is advantageously higher Needless to say, in the present invention, the use a strong absorbing solution, the C 0 ₂ 0. 5% or less at a pressure range of about atmospheric pressure to 1 0 atm, preferably Is absorbed and separated at l OOO ppm or less, more preferably at 100 or less. Also, when the absorbent liquid is absorbed saturated absorption solution was subjected to regeneration at a temperature of the transfer to 1 0 0~ 1 5 0 ° C to the regenerator, as well as recovering C_〇 ₂ gas, the absorbing solution after regeneration Return to absorption tower. The steam collected in the steam boiler in the reforming process is used as a heat source necessary to heat the absorbent during regeneration. Also, the exhaust heat and cathode off-gas of the fuel cell soak in the fuel cell power generation process can be used for the regeneration of the amide absorption liquid.

6) Installation process

In the present invention, a metanation step is provided for the purpose of reducing the carbon monoxide in the gas after the shift to 10 ppm or less, preferably 1 ppm or less. That is, the following methanation reaction (also referred to as metanation reaction) is performed in a methanation reactor filled with a methanation catalyst.

CO + 3 H ₂ → CH 4 + H ₂ 0 (1 1)

Hydrogen in the gas after absorption of carbon dioxide amine is used as hydrogen required for the reaction. Since the metanalysis reaction is an exothermic reaction, lowering the reaction temperature lowers the equilibrium concentration of carbon monoxide, but conversely lowers the reaction rate. Therefore, the reaction temperature is preferably in the range of 200 to 400 ° C. . As long as the catalyst promotes the metamorphic reaction, both the type and the shape are limited. Although not specified, nickel, iron and ruthenium methanation catalysts are suitable.

7) Hydrogen purification process

In the present invention, in the hydrogen purification step, a hydrogen purification method using a hydrogen storage alloy or a hydrogen purification method using a pressure-casing adsorption method is used.

In the second embodiment of the present invention, H ₂ S and HC 1 are each 10 ppm or less, preferably 1 ppm or less, more preferably 0.1 ppm or less, and C 0 is 10 ppm or less, preferably 1 ppm. below, C 0 _{_2,} H ₂ 0, respectively 1 0 0 ppm or less, preferably to Metaneshiyon after gas has been divided, respectively below 1 0 ppm, provided a higher hydrogen purification E by hydrogen occlusion metal base, the gas Into the vessel containing the hydrogen-absorbing alloy, occludes the hydrogen while cooling it into the hydrogen-absorbing alloy, and separates N ₂ and the main body from the hydrogen. After purging the gas, methane gas and residual hydrogen gas as hydrogen purification off-gas, and then heating the hydrogen storage alloy to release hydrogen, the hydrogen gas is pressurized and stored in the hydrogen tank, or the hydrogen tank is Via fuel cell Supplied to the process. Nitrogen and mains in the released and purified hydrogen gas are respectively reduced to less than 100 ppm, and the hydrogen concentration reaches 99.9% or more. Any hydrogen storage alloy may be used as long as it has a large hydrogen storage capacity.However, a low-level exhaust heat of about 70 ° C generated from a phosphoric acid fuel cell or a polymer electrolyte fuel cell during hydrogen release is used. A hydrogen storage alloy having a storage / release characteristic of 1 to 10 atm, preferably 3 to 7 atm at a hydrogen release pressure of 70 ° C is desirable so that it can be used as a heat source for heating. Examples of the alloy include a LaNi5 alloy and a TiFe alloy. The hydrogen storage / release reaction by the La Ni ₅ alloy is described below. Hydrogen storage reaction: La Ni ₅ + 3 H ₂ → La Ni ₅ H ₆ + heat release (13) Hydrogen release reaction: La Ni ₅ H ₆ → La Ni 5 + 3 H ₂ + heat absorption (1 4) As shown in the above equation (13), the hydrogen storage reaction is a heat release reaction, so when the hydrogen partial pressure is constant, especially when the hydrogen partial pressure is low, the hydrogen storage alloy is cooled during hydrogen storage to store the hydrogen. Need to be kept low. The lower the hydrogen storage temperature is, the more advantageous it is. However, a temperature of 12 to 32 ° C, which can be easily maintained by cooling water, is preferable. In addition, since the hydrogen release reaction is an endothermic reaction as shown in the above equation (14), in order to increase the pressure of the released hydrogen, it is necessary to heat the hydrogen storage alloy at the time of releasing hydrogen to raise the release temperature. In the present invention, in the embodiment in which the fuel cell power generation step is provided as the heating heat source, the cooling water around 70 ° C. of the fuel cell pack is used, and in the embodiment in which the fuel cell power generation step is not provided. Uses recovered steam or hot water in the reforming step. Further, the hydrogen storage alloy is housed in a heat exchanger type container provided with a heat exchange means such as a jacket tube for heat exchange, and the hydrogen storage alloy is used for continuously absorbing and releasing hydrogen. At least two storage containers are provided and switched by a solenoid valve.

Further, in the third aspect of the present invention, carbon dioxide to § Mi emission absorption after gas, provided the hydrogen purification step by pressure a swing adsorption method, the residual in the gas C0 _2, C_〇, methane and nitrogen The gas is adsorbed and removed by the adsorbent to purify hydrogen. That, C0 ₂ in the gas leads to the gas in the gas adsorption tower, C_〇 adsorbs separated methane and nitrogen is contacted with the adsorbent. C0 _2, CO, main Yun and to exert the maximum adsorption capacity of the adsorption tower to nitrogen, these are Nozomu Mashiku to fill the adsorbent in the adsorption tower showing a selective adsorptivity with respect to the gas, For example, zeolite molecular sieves or carbon molecular sieves or activated carbon or activated alumina is suitable. Low adsorption temperature Although very advantageous, a temperature range of 12 to 40 ° C, where temperature control is relatively easy, is preferred. Needless to say, the higher the gas pressure is, the more advantageous it is. However, in the present invention, a low pressure range of 10 atm or less is sufficient. When the adsorbent is saturated by adsorption, desorption is performed under normal pressure or by a vacuum pump, and the desorbed gas is discharged from the adsorption tower as a hydrogen purification off-gas, and the adsorbent is regenerated. As the desorption pressure is reduced by the vacuum pump, the pressure difference between the adsorption pressure and the desorption pressure increases, thereby improving the processing capacity of the adsorption tower. On the other hand, the power consumption of the vacuum pump increases, so the desorption pressure becomes 1 The range of 330 to 130 Pa (100 to LOT orr) is desirable. In order to separate and adsorb the water vapor, a packed bed of an adsorbent such as activated alumina or silica gel suitable for adsorbing the water vapor may be provided at a stage preceding the adsorption tower. In a third aspect of the present invention, the shift process and the carbon dioxide § Mi emission absorption step is provided between the hydrogen purification step by pressure a swing adsorption method, 6 0 C_〇 ₂ included in the shift after gas % or more, preferably after absorption separation over 90% in the Amin absorption step, residual 〇 0 ₂ and 00, by removing the methane and nitrogen in the hydrogen purification process by the pressure sweep rate ranging adsorption, hydrogen Increase recovery rate. When introduced into the hydrogen purification step the modified after gas directly to the absorption load of C 0 ₂ is large, there is a problem that the hydrogen recovery rate in hydrogen purification step is greatly reduced.

In the present invention, a part of the hydrogen purification offgas discharged from the hydrogen purification step is discharged to the outside of the system, and the rest is returned to the reforming step to perform reforming. The offgas is burned and the heat of combustion can be used as the heat of reforming in the reforming process or the heat of regeneration of the absorbent in the carbon dioxide amine absorption process.

8) Fuel cell power generation process In the present invention, the temperature of the hydrogen gas or hydrogen-containing gas produced in the gas treatment step is relatively low, the hydrogen concentration is high, and the content of carbon monoxide is low, so that the fuel cell used is relatively low. A phosphoric acid fuel cell operating at a temperature, particularly a polymer electrolyte fuel cell, is suitable. The cell reactions in the case of a phosphoric acid or solid polymer fuel cell are described below.

Anode reaction: H ₂ → 2 + 2 e-(15) Force sword reaction: 1/20 ₂ + 2 lT + 2 e → H 20 (16) That is, hydrogen gas or hydrogen-containing gas is used as a fuel cell Oxygen-containing gas is supplied to the anode electrode room of the stack to the power source electrode room, respectively, and power is generated by the battery reaction described above. The operating temperatures of the phosphoric acid fuel cell and the polymer electrolyte fuel cell are around 200 ° C and around 80 ° C, respectively.However, since the cell reaction involves heat generation, it is necessary to maintain the operating temperature. The sink needs to be cooled. In the present invention, the energy efficiency of the entire system can be improved by using the hot water of the stack cooling as a heating source for the main fermentation liquid. In order to ensure power generation efficiency and durability of the fuel cell in fuel cell power generation, 100% of the hydrogen gas sent to the anode electrode room in the gas tank was consumed instead of 100%. It is common practice to leave about a% and discharge it from the stack as anode off-gas. In the present invention, since the anodic off-gas can be recycled to the fuel cell stack as it is or after reforming methane again in the reforming step, there are features such as high hydrogen use efficiency and high fuel cell power generation efficiency. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an explanatory diagram of a fuel cell power generation system according to a first embodiment of the present invention. FIG. 2 is an explanatory diagram of the fuel cell power generation system according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a hydrogen production system according to a second embodiment of the present invention. FIG. 4 is an explanatory diagram of the hydrogen production system according to the second embodiment of the present invention. FIG. 5 is an explanatory diagram of a fuel cell power generation system according to a second embodiment of the present invention.

FIG. 6 is an explanatory diagram of a fuel cell power generation system according to a second embodiment of the present invention.

FIG. 7 is a basic configuration diagram of the fuel cell power generation system according to the first embodiment of the present invention.

FIG. 8 is a basic configuration diagram of a hydrogen production system according to a second embodiment of the present invention.

FIG. 9 is a basic configuration diagram of a fuel cell power generation system according to a third embodiment of the present invention.

FIG. 10 is an explanatory diagram of a hydrogen production system according to a third embodiment of the present invention.

FIG. 11 is an explanatory diagram of a fuel cell power generation system according to a third embodiment of the present invention.

FIG. 12 is a basic configuration diagram of a hydrogen production system according to a fourth embodiment of the present invention.

FIG. 13 is a basic configuration diagram of a fuel cell power generation system according to a fifth embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the fuel cell power generation system by organic matter methane fermentation according to the present invention j

An embodiment will be described with reference to FIGS. In FIGS. 1 to 13, the same or corresponding steps or members are denoted by the same reference numerals, and redundant description will be omitted.

FIG. 1 is a schematic diagram showing a fuel cell power generation system according to a first embodiment of the present invention. As shown in the figure, in the fuel cell power generation system of the present invention, the organic matter a is fermented in the methane fermentation step A, and the obtained digested gas b is processed in the gas treatment step B to produce the hydrogen-containing gas c. Then, it is supplied to the fuel cell power generation process C to generate power.

The gas treatment step B comprises: a gas pretreatment step 1 for adsorbing and / or absorbing and removing acidic gases such as hydrogen sulfide and hydrogen chloride in the digested gas obtained in the main fermentation step; A reforming step 2 in which the gas is reformed into hydrogen and carbon monoxide by a catalytic reaction with steam, and carbon monoxide in the reformed gas is converted into hydrogen gas and carbon dioxide by a catalytic reaction with steam. Metamorphosis step 3 for metamorphosis, carbon dioxide water absorption step 4 for bringing carbon dioxide in the gas after conversion into contact with water or an alkaline solution to absorb and separate it, and contacting residual carbon dioxide with the amine absorption liquid And carbon dioxide remaining in the decarbonated gas obtained in the carbon dioxide amine absorption step 5 and the carbon dioxide are subjected to a methanation reaction with hydrogen. Removing meta-metallization step 6 There. The gas after the reforming step 2 is sent to the shift step 3 through the boiler 11. FIG. 2 is a schematic diagram showing the fuel cell power generation system according to the first embodiment of the present invention in which the carbon dioxide water absorption step 4 is omitted.

In the fuel cell power generation process C, the hydrogen-containing gas c is supplied to the anode, and the oxygen-containing gas (05) is supplied to the cathode. Then, a part of the anode off-gas (04) is supplied to the reforming step 2 to be circulated and used, and the rest is exhaust gas (04). 8) is discharged as. The power source off-gas (06) is discharged from the fuel cell power generation process C and then sent to the reforming process 2 to be used as a combustion aid. The waste heat of the fuel cell (07) when the fuel cell is cooled is sent to the methane fermentation process A, where it is used as a heating source for the main fermented liquid.

FIG. 3 is a basic configuration diagram of the hydrogen production system according to the second embodiment of the present invention. As shown in the figure, in the hydrogen production system of the present invention, an organic substance a is fermented in a methane fermentation step A, and an obtained digestion gas b is processed in a gas treatment step B to produce a hydrogen-containing gas c.

The gas treatment step B comprises: a gas pretreatment step 1 for adsorbing and / or absorbing and removing acidic gases such as hydrogen sulfide and hydrogen chloride in the digested gas obtained in the main fermentation step; A reforming step 2 in which the gas is reformed into hydrogen and carbon monoxide by a catalytic reaction with steam, and hydrogen gas and carbon dioxide by a catalytic reaction of carbon monoxide in the reformed gas with steam. Metamorphosis step 3 for converting to carbon, carbon dioxide water absorption step 4 for bringing carbon dioxide in the gas after conversion into contact with water or an alkaline solution to absorb and separate, and residual carbon dioxide as an amine absorption liquid. The carbon dioxide amine absorption step 5 for contact absorption and separation, and the carbon monoxide and carbon dioxide remaining in the decarbonated gas obtained in the carbon dioxide amine absorption step 5 undergo a methanation reaction with hydrogen. Meta removal step 6 to remove more The method includes a hydrogen purification step 7 using a hydrogen-absorbing alloy in which methane and nitrogen in the gas after separation are separated from methane and nitrogen in the gas after purification, and hydrogen gas is purified and pressurized. The gas after the reforming step 2 is sent to the shift step 3 through the boiler 11. Part of the off-gas (09) in the hydrogen purification step 7 is returned to the reforming step 2, and the rest is discharged as exhaust gas (08). FIG. 4 shows a hydrogen production system according to a second embodiment of the present invention in which the carbon dioxide water absorption step 4 is omitted. FIG.

FIG. 5 is a schematic diagram showing a fuel cell power generation system according to the second embodiment of the present invention. As shown in the figure, in the fuel cell power generation system of the present invention, the organic matter a is fermented in the methane fermentation step A, and the obtained digested gas b is processed in the gas treatment step B to produce hydrogen gas c. Power is supplied to fuel cell power generation process C to generate electricity. The gas treatment step B is the same as the gas treatment step shown in FIG. Then, the hydrogen gas c purified and pressurized in the hydrogen purification step 7 is used as fuel, and the oxygen-containing gas is supplied as oxidant gas to the anode and power source of the fuel cell battery in the fuel cell power generation step C to generate electricity. I do. Also, the anodic off-gas (04) discharged from the fuel cell power generation process C is supplied to the anode and recycled. The power source off-gas (06) is discharged from the fuel cell power generation process C and then sent to the reforming process 2 where it is used as a combustion aid. The exhaust heat of the fuel cell (07) when the fuel cell is cooled is sent to the main fermentation step A and used as a heating source for the main fermented liquid. In addition, the screen exhaust heat (07) is also sent to the hydrogen purification step 7, where it is effectively used. FIG. 6 is a schematic diagram showing a fuel cell power generation system according to a second embodiment of the present invention in which the carbon dioxide water absorption step 4 is omitted.

FIG. 10 is a basic configuration diagram of the hydrogen production system according to the third embodiment of the present invention. As shown in the figure, in the hydrogen production system of the present invention, an organic substance a is fermented in a methane fermentation step A, and the obtained digested gas b is processed in a gas treatment step B to produce a hydrogen-containing gas c.

The gas treatment step B comprises: a gas pretreatment step 1 for adsorbing and / or absorbing and removing acidic gases such as hydrogen sulfide and hydrogen chloride in the digested gas obtained in the main fermentation step; A reforming step 2 in which the main component is reformed into hydrogen and carbon monoxide by a catalytic reaction with water vapor, and carbon monoxide in the reformed gas Metamorphosis process that converts to hydrogen gas and carbon dioxide by catalytic reaction with steam

3, carbon dioxide amine absorption step 5 in which carbon dioxide in the gas after conversion is brought into contact with the amine absorption liquid to absorb and separate it, and remaining in the decarbonated gas obtained in the carbon dioxide amine absorption step 5. And a hydrogen purification step 7 in which carbon monoxide, carbon dioxide, methane, and nitrogen are adsorbed and separated by an adsorbent. The gas after the reforming step 2 is sent to the shift step 3 through the boiler 11. A part of the off-gas (09) of the hydrogen purification step 7 is returned to the reforming step 2, and the rest is discharged as an exhaust gas (08).

FIG. 11 is a schematic diagram showing a fuel cell power generation system according to a third embodiment of the present invention. As shown in the figure, in the fuel cell power generation system of the present invention, the organic substance a is fermented in the main fermentation step A, and the obtained digested gas b is processed in the gas processing step B to produce hydrogen gas c. Then, it is supplied to the fuel cell power generation process C to generate power. The gas treatment step B is the same as the gas treatment step shown in FIG. Then, the hydrogen gas c purified in the hydrogen purification step 7 is used as fuel, and the oxygen-containing gas is supplied as an oxidant gas to the anode and cathode of the fuel cell unit in the fuel cell power generation step C, respectively. To generate electricity. In addition, the anode off-gas (04) discharged from the fuel cell power generation process C is supplied to the anode and recycled. The power source off-gas (06) is discharged from the fuel cell power generation process C and then sent to the reforming process 2 where it is used as a combustion aid. The waste heat (07) of the fuel cell when the smoke is cooled is sent to the main fermentation step A, where it is used as a heating source for the methane fermentation liquor. The stack waste heat (07) is also sent to the hydrogen purification step 7, where it is effectively used.

FIG. 7 is a basic configuration diagram of the fuel cell system according to the first embodiment of the present invention. Organic matter a is fermented in methane fermentation step A to produce digestive gas b, Store in digestive gas holder 101. Then, the digestive gas b is sent to the scrano 11 in the pretreatment step 1 by the digestive gas processor 102, where the digestive gas b is brought into contact with the washing water 13 to remove the hydrogen sulfide and hydrogen chloride in the digestive gas. And other acid gases should be removed below 10 ppm, preferably below 1 ppm. The washing water 13 is circulated to the scrano ^; 1 1 by the circulation pump 1 2, but a part of the washing water 13 is constantly withdrawn as the washing waste liquid 14, and at the same time, the same amount of new washing makeup water 15 Replenish. Here, 0.05 to 5% of viscous soda is added to the supplied cleaning and replenishing water 15. Next, the cleaning gas 16 that has exited the scrubber 11 is branched, and the reformed feed gas 17 is sent to the dry desulfurizer 19. On the other hand, the fuel gas 18 is sent to the burner 23 b of the reforming step 2.

H ₂ S is reduced to 0.1 ppm or less, preferably to 0.01 ppm or less in the dry desulfurizer 19, and the reformed feed gas is pressurized to a pressure of 10 atm or less by the compressor 21. After being sent to the reforming process 2 and preheated by the combustion exhaust gas 25 b in the heat exchanger 22, it is combined with the reforming steam 27 generated in the steam boiler 26 to form the reformer 23. It enters the reforming catalyst packed bed 23a. In the catalyst packed bed 23a, methane is reformed into hydrogen and carbon monoxide by a reforming reaction with steam. Since the reforming reaction is an endothermic reaction at 700 to 800 ° C. or 600 to 700 ° C., the fuel gas 18 and the oxygen-containing gas 25 a are burned by the parner 23 b. And supplying the reaction heat. The reformed high-temperature gas 24a is introduced into the steam boiler 26 to generate the reforming steam 27 and the absorbing liquid regeneration steam 28a in the subsequent carbon dioxide amine absorption step. Next, the reformed gas 24 b cooled to 150 to 200 ° C. is led to the shift reactor 31 of the shift step 3, and carbon monoxide and water vapor are turned to 200 to 250 ° C. Is converted to carbon dioxide and hydrogen by the catalytic reaction in step, and the concentration of carbon monoxide is reduced to 1% or less, preferably 0.5% or less. Then, send the modified gas after 3 2 heat recovery at the gas cooler 3 3, after cooling, to the absorber 4 1 C 0 ₂ Water absorption step 4. Here, a heat exchanger may be provided to exchange heat between the post-transformation gas 32 and the condensate 28b to cool the post-transformation gas 32 and preheat the condensate 28b. And C 0 ₂ absorption raw water 4 3 sent by the absorption column 4 1 transformer after gas 3 2 and the liquid feed pump 4 4 to contacting Therefore, the C 0 ₂ gas 3 2 6 0% or more, preferably Absorb 90% or more, then discharge out of the system together with water 55 (carbonated water) after absorption. On the other hand, sends a C 0 ₂ Water absorption after gas 4 2 to the absorber 5 1 a of C 0 ₂ § Mi emission absorption step 5 in the next step.

In the carbon dioxide amine absorption step 5, the post-regeneration gas is brought into contact with the post-regeneration absorbent 53a to reduce carbon dioxide to 0.5% or less, preferably 0.1% or less, more preferably 0.1% or less. 0 Remove to 1% or less. At the same time, acidic gases such as hydrogen sulphate and hydrogen chloride are further removed in this step. On the other hand, the absorbed liquid 53b after absorption is led to the regeneration tower 51b via the heat exchanger 54a, and heated to 100 to 150 ° C by the steam 28a in the heat exchanger 54c. Then regenerate the absorbing solution and collect carbon dioxide 57. The condensate 28 b is returned from the heat exchanger 54 c to the steam boiler 26. After regeneration, the absorbent 53a is sent to the absorption tower 51a again by the liquid sending pump 55 via the heat exchanger 54a and the gas cooler 54b. Reference numeral 56b denotes an absorption replenisher.

Then, send the Metaneshiyo down reactor 6 2 C 0 ₂ absorption after gas 5 2 exiting the carbon dioxide § Mi emission absorption step 5 through the heat exchanger 61 of the main Yuneichi to down step 6. Main evening Ne one Deployment reactor 6 each C_〇 ₂ and C 0 in the gas in 2 the methanation reaction with H ₂ 1 0 O ppm or less and 1 O ppm hereinafter, is preferably removed following 1 p pm You. The gas 63 coming out of the message reactor 62 exits the heat exchanger 61 and the hydrogen-containing gas holder. The fuel gas is supplied to the anode electrode room of the fuel cell stack 81 of the fuel cell power generation process C as fuel gas 85a through the airflow 67, and the air 82 is supplied to the cathode 81 of the stack 81 by the air blower 83. Power is supplied to the room to generate electricity. Reference numeral 8 8 is a generated power output.

In the present embodiment, the power source gas 84 discharged from the power source chamber of the stack 81 can be used as the combustion aid 25a in the reforming step 2. About 10% of the anode off-gas 86 discharged from the anode electrode chamber of the stack 81 is discharged to the system as exhaust gas (08), and the remaining 90% is discharged to the reforming process 2 The methane is returned to the suction port of compressor 21 and reformed again by methane generated by the meta-ion and methane that could not be reformed by the reforming reaction. In addition, the cooling water outlet 87a of the stack 81 is circulated to the methane fermentation tank A1 of the methane fermentation step A and the hydrogen purification step 7, and heat from the waste heat is effectively used by heat exchange. Then, the stack cooling water after the heat exchange returns to the cooling water inlet 87 b of the stack 81.

FIG. 8 is a basic configuration diagram of a hydrogen production system according to a second embodiment of the present invention. The gas 63 after exiting the metalation reactor 62 described in the first embodiment passes through the heat exchanger 61, and passes through the gas cooler 64, the gas-water separator 65, and the dehumidifier 66. After the water in the gas is removed to 100 ppm or less, preferably 100 ppm or less, it is sent to the hydrogen purification step 7. The dehumidifier used here is preferably one filled with a moisture adsorbent, for example, one filled with activated alumina or silica gel.

The hydrogen refining process 7 includes at least two series of hydrogen storage alloy containers 7 1 a and 7 lb, and at least one series of hydrogen tanks 72. The two series of hydrogen storage alloy containers perform hydrogen storage and release, respectively.The switching between hydrogen storage and release is performed by the crude hydrogen inlet solenoid valves 74a and 74b, the purified hydrogen outlet solenoid valves 75a and 75b, methane, nitrogen outlet solenoid valves 76a, 76b. Here, a case where the alloy container 71a performs the hydrogen releasing operation and the alloy container 7lb performs the hydrogen absorbing operation will be described.

In this case, the solenoid valve 74b is opened, and the gas 63 after the metanalysis is introduced into the alloy container 71b to absorb hydrogen at a temperature of 12 to 35 ° C. Cooling water 78a is introduced into the jacket of the alloy container 71b to cool and remove the heat generated when storing hydrogen. After saturation storage, close solenoid valve 74 b and open solenoid valve 76 b to store methane, nitrogen, residual hydrogen, and hydrogen containing trace amounts of impurity gas in the voids in the alloy packed bed of alloy container 71 b The purification process off-gas 73 is discharged. On the other hand, the solenoid valves 74a and 76a are closed and the solenoid valve 75a is open.The steam 79a of 120 ° C or higher is applied to the jacket of the alloy container 71a. The hydrogen absorbed by the hydrogen storage alloy is introduced and released, and the released purified hydrogen 77a is supplied to a demand destination such as a fuel cell via a hydrogen tank 72. The purity and pressure of the purified hydrogen gas 77a and 77b reach 99.9% or more and 2 atm or more, respectively.

Next, about 10% of the discharged hydrogen purification off-gas 73 is discharged out of the system as exhaust gas (08), and the remaining 90% is supplied to the suction port of the compressor 21 in the reforming step 2. It is returned and reforms the methane generated by the process and the methane that could not be reformed by the reforming reaction.

FIG. 9 is a basic configuration diagram of a fuel cell power generation system according to a third embodiment of the present invention. The purified hydrogen gas 77 b described in the second embodiment is supplied to the anode electrode room of the fuel cell battery 81 of the fuel cell power generation step C to generate power. In this embodiment, the anode off-gas 86 flowing out of the anode electrode chamber of the stack 81 is circulated to the anode chamber of the stack 81 via the ejector 85. Here, a blower or a compressor can be used instead of the ejector 85 _c In addition, the cooling water 87a of the stack 81 is introduced into the jacket of the alloy container # 1a in the hydrogen purification step 7, and the hydrogen storage alloy that has absorbed the hydrogen is heated to release purified hydrogen 77a. On the other hand, the stack cooling water 87 b exiting the jacket of the alloy container 7 la is circulated to the stack 81 in order to cool the stack 81 again. As an example of the cooling temperature of the hydrogen storage alloy and the hydrogen release temperature of the hydrogen storage alloy, the cooling water 87 a (outlet), ie, the hydrogen storage alloy container, that exited the fuel cell battery 81 was prepared. The temperature of the hot water at the jacket inlet of 71 a is 75 and the temperature of the stack cooling water 87 b (inlet), that is, the temperature of the hot water at the jacket outlet of the hydrogen storage alloy container 71 a is 70 ° C. It may be.

FIG. 12 is a basic configuration diagram of a hydrogen production system according to a fourth embodiment of the present invention. The post-amin absorption gas 52 exiting the amine absorption tower 51 a described in the first embodiment is sent to the hydrogen purification step 7. The hydrogen purification step 7 comprises at least two lines of adsorption towers and at least one line of hydrogen tanks 72. Adsorption tower sequentially gas components other than hydrogen in the 3 series in this embodiment, i.e., C 0 _2, CO, adsorption and desorption of such as methane and nitrogen performed.

Purified hydrogen 77 coming out of the adsorption tower 71 is supplied to a demand destination such as a fuel cell via a hydrogen tank 72. The hydrogen concentration of the purified hydrogen gas 77 reaches 99% or more, preferably 99.9% or more, and the C0 concentration drops to 10 ppm or less, preferably 1 ppm or less.

On the other hand, about 10% of the hydrogen purification off-gas 73 discharged from the vacuum pump 74 is discharged out of the system as an exhaust gas (08), and the remaining 90% is discharged to the compressor 2 1 of the reforming process 2. The methane that cannot be reformed by the reforming reaction is reformed again.

FIG. 13 is a basic configuration diagram of a fuel cell power generation system according to a fifth embodiment of the present invention. The purified hydrogen gas 77 described in Example 4 was used for fuel cell power generation. Power is supplied to the anode room of the fuel cell stack 81 in step C to generate electricity. In this embodiment, the anode off-gas 86 that has flowed out of the anode electrode room of the storage 81 is circulated to the anode room of the stack 81 via the ejector 85. Here, a blower or a compressor can be used in place of the ejector 85, and the cooling water 87a of the stack 81 is circulated to the methane fermentation tank A1 of the methane fermentation step A to exchange heat. This heats the methane fermentation liquor to effectively use the stack waste heat. Then, the stack cooling water after the heat exchange returns to the cooling water inlet 87 b of the stack 81.

As described above, according to the present invention, a high-quality hydrogen gas or a hydrogen-containing gas suitable for fuel cell power generation is produced by subjecting organic matter to methane fermentation and reforming the generated digestive gas to produce a fuel cell. Power generation can be performed efficiently. Industrial applicability

The present invention relates to an energy conversion technique for converting chemical energy of combustibles into electric energy with high efficiency. INDUSTRIAL APPLICABILITY The present invention can be used for a system for producing methane gas or hydrogen-containing gas from obtained digestion gas by methane fermentation of organic waste such as organic waste liquid or organic slurry having a relatively high concentration, and It can also be used in power generation systems that generate electricity by using the produced hydrogen gas or hydrogen-containing gas as fuel gas for fuel cells.

Claims

The scope of the claims

1. A method for producing hydrogen gas from a gas processed in a reforming step and a metamorphosis step by subjecting combustibles to methane fermentation,

A method for producing hydrogen gas, comprising subjecting a gas treated in the reforming step and the shift step to a carbon dioxide amine absorption step and a subsequent mes- sage step.

2. The hydrogen gas according to claim 1, wherein the gas processed in the reforming step and the shift step undergoes a carbon dioxide water absorption step as a preceding stage of the carbon dioxide amine absorption step. Manufacturing method.

3. Methane fermentation of organic matter, comprising a methane fermentation step of methane fermentation of organic matter, a gas treatment step of reforming digestive gas generated in the methane fermentation step to produce hydrogen-containing gas, and a fuel cell power generation step. A fuel cell power generation method,

The gas treatment step includes a gas pretreatment step of adsorbing and / or absorbing and removing acidic gases such as hydrogen sulfide and hydrogen chloride in the digested gas obtained in the main fermentation step; A reforming step of reforming the main gas into hydrogen and carbon monoxide by a catalytic reaction with steam, and a conversion of carbon monoxide in the reformed gas into hydrogen gas and carbon dioxide by a catalytic reaction with steam Metamorphosis process, carbon dioxide water absorption process in which carbon dioxide in the gas after the modification is brought into contact with water or an alkaline solution to absorb and separate, and / or carbon dioxide amine absorption in which it is brought into contact with an amide absorption solution to absorb and separate And carbon monoxide and carbon dioxide remaining in the decarbonated gas obtained in the carbon dioxide amine absorption step. And a metalation step for removing by a methanation reaction,

In the fuel cell power generation step, the hydrogen-containing gas obtained in the metalation step is used as a fuel gas, and the oxygen-containing gas is supplied as an oxidant gas to an anode and a power source of a fuel cell stack. A fuel cell power generation method by methane fermentation of organic matter, characterized by generating power.

4. Combustion of a portion of the digested gas or the gas after desulfurization after the gas pretreatment step as a fuel in a combustor, and the supply of reforming reaction heat and the reaction temperature in the reforming step is performed by the obtained combustion heat. Item 3. The fuel cell power generation method according to Item 3, wherein the organic matter is subjected to methane fermentation.

5. The fuel cell power generation method according to claim 3, wherein part of the anode offgas discharged from the fuel cell power generation step is returned to the reforming step.

6. A fuel cell power generation method by methane fermentation of organic matter, wherein the power source off-gas discharged from the fuel cell stack is sent to the reforming step according to claim 3 and used as a combustion aid.

7. The fuel cell power generation method according to any one of claims 3 to 6, wherein the fuel cell is a polymer electrolyte fuel cell or a phosphoric acid fuel cell.

8. A method for producing hydrogen by methane fermentation of organic matter, comprising: a methane fermentation step of methane fermenting organic matter; and a gas treatment step of reforming digestive gas produced in the methane fermentation step to produce hydrogen-containing gas. ,

The gas treatment step includes a gas pretreatment step of adsorbing and / or absorbing and removing acidic gases such as hydrogen sulfide and hydrogen chloride in the digested gas obtained in the main fermentation step; A reforming step of reforming the main gas into hydrogen and carbon monoxide by a catalytic reaction with steam, and a conversion of carbon monoxide in the reformed gas into hydrogen gas and carbon dioxide by a catalytic reaction with steam Metamorphosis process, carbon dioxide water absorption process in which carbon dioxide in the gas after the modification is brought into contact with water or an alkaline solution to absorb and separate, and / or carbon dioxide amine absorption in which it is brought into contact with an amide absorption solution to absorb and separate A step of removing carbon monoxide and carbon dioxide remaining in the decarbonated gas obtained in the carbon dioxide amine absorption step by reacting with hydrogen with methanation; and Moisture in gas A method for producing hydrogen by methane fermentation, comprising the steps of: separating methane and nitrogen in gas after dehumidification, separating methane and nitrogen in gas, purifying hydrogen gas, and increasing the pressure by using a hydrogen storage alloy.

9. Combustion of a portion of the digested gas or the gas after desulfurization after the gas pretreatment step in a combustor as fuel, and the supply of reforming reaction heat and the reaction temperature in the reforming step by the obtained combustion heat. 9. The method for producing hydrogen by methane fermentation of organic matter according to claim 8, wherein the hydrogen is maintained.

10. The hydrogen purification method according to claim 8, wherein a part of the hydrogen purification offgas discharged from the hydrogen purification step is returned to the reforming step.

11. The hydrogen gas purified in the hydrogen purification step of claim 8 is used as fuel gas, and the oxygen-containing gas is used as oxidant gas. Fuel cell power generation method by methane fermentation of organic matter, characterized in that anodic off-gas discharged from the power generation process is supplied to the anode and supplied to the anode for recycling.

12. The methane fermentation of organic matter, wherein the power source gas discharged from the fuel cell sock according to claim 11 is sent to the reforming step according to claim 8 and used as a combustion aid. Fuel cell power generation method.

13. The fuel cell power generation method according to claim 11 or 12, wherein the fuel cell is a polymer electrolyte fuel cell or a phosphoric acid fuel cell.

14. A hydrogen production method by main fermentation of organic matter, comprising: a methane fermentation step of methane fermentation of organic matter, and a gas treatment step of reforming digestive gas produced in the methane fermentation step to produce hydrogen-containing gas. And

The gas treatment step includes a gas pretreatment step of adsorbing and / or absorbing and removing acidic gases such as hydrogen sulfide and hydrogen chloride in the digested gas obtained in the main fermentation step; A reforming process for reforming the main gas to hydrogen and carbon monoxide by a catalytic reaction with steam, and a reforming process for transforming carbon monoxide in the reformed gas into hydrogen gas and carbon dioxide by a catalytic reaction with steam A carbon dioxide amine absorption step of bringing carbon dioxide in the gas after the conversion into contact with the amine absorption liquid to absorb and separate the carbon dioxide from the gas, and a desorption step obtained in the carbon dioxide amine absorption step. A method for producing hydrogen by methane fermentation, comprising: a hydrogen refining step of purifying hydrogen by adsorbing and separating carbon monoxide, carbon dioxide, methane, and nitrogen remaining in gas after carbon dioxide onto an adsorbent.

15. Combustion of a portion of the digested gas or the gas after desulfurization after the gas pretreatment step as a fuel in a combustor, and the supply of reforming reaction heat and the reaction temperature in the reforming step are performed by the obtained combustion heat. 15. The method for producing hydrogen by main fermentation of organic matter according to claim 14, wherein the hydrogen is maintained.

16. The hydrogen purification method according to claim 14, wherein a part of the hydrogen purification offgas discharged from the hydrogen purification step is returned to the reforming step.

17. The hydrogen gas purified in the hydrogen purification step in claim 14 is supplied as fuel gas, and the oxygen-containing gas is supplied as oxidant gas to the anode and power source of the fuel cell stack in the fuel cell power generation step. A fuel cell power generation method using methane fermentation of organic matter, characterized in that anodic off-gas discharged from the fuel cell power generation process is supplied to the anode and recycled.

18. An organic substance characterized in that the power source gas discharged from the fuel cell battery in claim 17 is sent to the reforming step according to claim 14 and used as a combustion aid. Fuel cell power generation method by methane fermentation.

19. The fuel cell power generation method according to claim 17 or 18, wherein the fuel cell is a polymer electrolyte fuel cell or a phosphoric acid fuel cell.

20. A methane fermentation tank for performing methane fermentation of organic matter, a gas treatment apparatus for producing hydrogen-containing gas by reforming digestive gas generated in the methane fermentation tank, and a fuel cell A fuel cell power generation system,

The gas treatment device includes a scrubber and / or a dry desulfurizer that adsorbs and / or absorbs and / or removes acidic gases such as hydrogen sulfide and hydrogen chloride in the digested gas obtained in the methane fermentation tank; and A reformer that reforms the main gas to hydrogen and carbon monoxide by a catalytic reaction with water vapor, and converts carbon monoxide in the reformed gas into hydrogen gas and carbon dioxide by a catalytic reaction with water vapor The first absorption tower, which absorbs and separates carbon dioxide in the gas after conversion by contacting it with water or an alkaline solution, and / or the first absorber that absorbs and separates by contacting with an amide absorption liquid (2) a methylation reaction packed with an absorption tower and a methanation catalyst that removes carbon monoxide and carbon dioxide remaining in the decarbonated gas obtained in the second absorption tower by hydrogenation with hydrogen. A fuel cell, wherein the fuel cell comprises: The hydrogen-containing gas obtained in the medium-filled reactor is used as fuel gas, and the oxygen-containing gas is supplied as oxidant gas to the anode and power source of the fuel cell stack to generate power. Characteristic fuel cell power generation system by methane fermentation of organic matter.

21. A part of the digested gas or the desulfurized gas discharged from the scrubber is burned as a fuel in a combustor, and the obtained combustion heat is applied to the reformer. 20. The fuel cell power generation system according to claim 20, wherein heat of the reforming reaction is supplied and the reaction temperature is maintained.

22. The fuel cell power generation system according to claim 20, wherein the anode off-gas discharged from the fuel cell battery is returned to the reformer.

23. A fuel cell power generation system based on organic methane fermentation, wherein power source off-gas discharged from the fuel cell stack is sent to the reformer and used as a combustion aid.

24. The fuel cell according to any one of claims 20 to 23, wherein the fuel cell is a polymer electrolyte fuel cell or a phosphoric acid fuel cell. Power generation system.

25. A hydrogen production system based on methane fermentation of organic matter, comprising a methane fermentation tank for methane fermentation of organic matter and a gas treatment device for reforming digestive gas generated in the methane fermentation tank to produce hydrogen-containing gas. hand,

The gas treatment device includes a scrubber and / or a dry desulfurizer for adsorbing and / or absorbing and removing acidic gases such as hydrogen sulfide and hydrogen chloride in digested gas obtained in the main fermenter; A reformer that reforms the gas in the catalyst into hydrogen and carbon monoxide by a catalytic reaction with steam, and a hydrogen gas and carbon dioxide by a catalytic reaction of carbon monoxide in the reformed gas with steam The first absorption tower and / or the amine absorption liquid that absorbs and separates the carbon dioxide in the gas after conversion by contacting it with water or an alkaline solution. Filled with a second absorption tower to be separated and separated, and a methanation catalyst that removes carbon monoxide and carbon dioxide remaining in the decarbonized gas obtained in the second absorption tower by hydrogenation with hydrogen. After the desorption of moisture in the gas after the gasification, the methane and nitrogen in the gas after the metanation were separated, the hydrogen gas was purified, and the hydrogen storage alloy was charged to increase the pressure. A hydrogen production system based on methane fermentation of organic matter, comprising a metal storage container.

26. Combustion of a part of the digested gas or the desulfurized gas discharged from the scrubber as a fuel in a combustor, and supply of the reaction heat and the reaction temperature in the reformer by the obtained combustion heat The hydrogen production system according to claim 25, wherein methane fermentation of organic matter is performed.

27. The organic matter according to claim 25, wherein a part of the hydrogen purification offgas discharged from the hydrogen storage alloy storage container is returned to the reformer to reform methane in the hydrogen purification offgas again. Hydrogen production system using methane fermentation.

28. The hydrogen gas purified by the alloy container in claim 25 is used as fuel gas, and the oxygen-containing gas is supplied as oxidant gas to the anode and power sword of the fuel cell battery, respectively, to generate electricity. A fuel cell power generation system based on methane fermentation of organic matter, characterized in that anodic off-gas discharged from a battery pack is supplied to the anode and recycled.

29. The methane fermentation of organic matter, wherein the power source gas discharged from the fuel cell stack according to claim 28 is sent to the reformer according to claim 25 and used as a combustion aid. Fuel cell power generation system.

30. The fuel cell power generation system according to claim 28 or claim 29, wherein the fuel cell is a polymer electrolyte fuel cell or a phosphoric acid fuel cell.

3 1. A hydrogen production system based on methane fermentation of organic matter, comprising a methane fermentation tank for methane fermentation of organic matter and a gas treatment device for reforming digestive gas generated in the methane fermentation tank to produce hydrogen-containing gas. hand,

The gas treatment device includes a scrubber and / or a dry desulfurizer for adsorbing and / or absorbing and removing acidic gases such as hydrogen sulfide and hydrogen chloride in digested gas obtained in the main fermenter; A reformer that reforms the gas in the catalyst into hydrogen and carbon monoxide by a catalytic reaction with steam, and a hydrogen gas and carbon dioxide by a catalytic reaction of carbon monoxide in the reformed gas with steam A metamorphic reactor, a carbon monoxide remaining in the gas after the decarbonation obtained in the absorption tower, A hydrogen production system by methane fermentation of organic matter, comprising an adsorption tower filled with an adsorbent for adsorbing and separating carbon dioxide, methane and nitrogen.

32. Combustion of a portion of the digested gas or the desulfurized gas discharged from the scrubber in a combustor as fuel, and the supply of reforming reaction heat and the reaction temperature in the reformer by the obtained combustion heat Claims that maintain Item 31. A hydrogen production system by methane fermentation of organic matter according to Item 31.

33. The organic substance according to claim 31, wherein a part of the hydrogen purification offgas discharged from the adsorption tower is returned to the reformer to reform methane in the hydrogen purification offgas again. Hydrogen production system by methane fermentation.

34. The hydrogen gas purified by the adsorption tower according to claim 31 as a fuel gas and the oxygen-containing gas as an oxidant gas are supplied to an anode and a power source of a fuel cell unit, respectively, to generate power. A fuel cell power generation system based on methane fermentation of organic matter, characterized in that anode off-gas discharged from the fuel cell stack is supplied to the anode and recycled.

35. An organic material, characterized in that the power source gas discharged from the fuel cell battery in claim 34 is sent to the reformer according to claim 31 and used as a combustion aid. A fuel cell power generation system using fermentation.

36. The fuel cell power generation system according to claim 34 or 35, wherein the fuel cell is a polymer electrolyte fuel cell or a phosphoric acid fuel cell.