WO2001028916A1

WO2001028916A1 - Method of producing hydrogen by gasification of combustibles and electric power generation using fuel cell

Info

Publication number: WO2001028916A1
Application number: PCT/JP2000/007366
Authority: WO
Inventors: Hiroyuki Fujimura; Takahiro Oshita; Qingquan Su; Kazuo Kinoshita; Norihisa Miyoshi; Katsutoshi Naruse
Original assignee: Ebara Corporation
Priority date: 1999-10-21
Filing date: 2000-10-23
Publication date: 2001-04-26
Also published as: AU7953500A

Abstract

A method of producing hydrogen by gasification of combustibles which has a gasification step (A) of gasifying a first combustible (a) and a gas treatment step (C) of purifying a formed gas (c) formed in the gasification step (A), characterized in that the method further comprises a modification step (B) of admixing the formed gas (c) obtained in the gasification step (A) with a second combustible (e) and carrying out a modification reaction of the second combustible (e), and the resulting modified gas (f) is introduced to the gas treatment step (C).

Description

Description Hydrogen production method by gasification of combustibles and fuel cell power generation method

The present invention relates to a technology for recovering the chemical energy of combustibles in the form of hydrogen gas, and further to an energy conversion technology for converting the energy into electrical energy with high efficiency.In particular, the present invention relates to combustibles such as combustible waste and coal. The present invention relates to a method for producing hydrogen gas from gas produced by gasification or reforming, and a method for generating electricity by supplying the produced hydrogen gas to a fuel cell. Here, flammable waste includes municipal waste, solidified fuel, slurry fuel, waste paper, waste plastic, waste FRP, biomass waste, automobile waste, industrial waste such as waste wood, and low-grade coal. , Organic waste liquid, waste oil, etc. Background art

In recent years, with increasing awareness of environmental protection, various attempts have been made regarding power generation methods that use flammable waste as an energy source. As one of the approaches, combustibles are gasified under pressure, and the resulting gas is used to drive the gas bin, while the exhaust gas from the gas turbine is recovered by a waste heat boiler to drive the steam bin. However, there is a combined cycle power generation method that aims to achieve high-efficiency power generation by using a combined gas cycle and a steam turbine to generate combined cycle power.

However, the above-mentioned combined cycle power generation method is disadvantageous in that it is difficult to apply to low-calorie gas, and because it is a power generation method involving combustion, pollution that adversely affects the environment, such as nitrogen oxides, sulfur oxides, and dioxins. May generate substances and cause an increase in environmental load. In recent years, fuel cell technology, which is a power generation method that directly converts the chemical energy of hydrogen into electric energy, has been developed with high efficiency and low environmental impact, and is reaching the stage of practical use. Therefore, the development of technology for generating gas from combustible waste as a raw material, further purifying hydrogen from the generated gas, and generating electricity with this environmentally-friendly fuel cell is being promoted. However, when waste is used as a raw material, fuel components in the waste fluctuate greatly, unlike ordinary fuel, and the seasonal fluctuations in Japan are particularly large. However, it is almost impossible to generate fuel gas with a stable component at all times.

On the other hand, in order to make use of power generation technologies such as fuel cells, it is essential to develop a method for producing high-quality hydrogen gas and to establish an infrastructure that is connected to water cables such as hydrogen gas stations. This means that high-concentration hydrogen gas containing almost no poisonous gas components such as hydrogen sulfide and carbon monoxide needs to be supplied to polymer electrolyte fuel cells, which are optimal for fuel cell vehicles and home power generation methods. At present, natural gas and methanol, which are relatively easy to use, are used as raw materials for hydrogen.

However, in order to produce hydrogen gas from gas or liquid fuel such as natural gas or methanol, a reforming process must be performed. Usually, a steam reforming reaction is used, but since this reaction is an endothermic reaction that proceeds under high temperature conditions, a part of the raw fuel or the reformed gas is burned to reduce the combustion heat to maintain the temperature of the reforming reaction. It is generally used for supplying reaction heat and generating steam. For this reason, the thermal efficiency of the reforming process remains at around 70-80%. Disclosure of the invention

In view of the above-mentioned circumstances, the present invention converts gaseous combustibles into hydrogen gas stations or power plants that do not pollute the environment, in order to convert waste incineration facilities to hydrogen gas stations or environmentally friendly power plants. A method for stably producing hydrogen gas suitable for fuel cells, especially polymer electrolyte fuel cells, regardless of the seasons, etc. from the produced gas, and supplying the produced hydrogen gas to the fuel cell to achieve high efficiency and It is an object of the present invention to provide a non-incineration power generation method with low environmental load.

The present inventors have conducted intensive studies to solve the above problems, and as a result, efficiently produced hydrogen gas suitable for fuel cell power generation from low-grade gas generated by gasification of combustibles shown in FIGS. 1 and 2. The present invention, which provides a hydrogen production method and a fuel cell power generation method, has been completed.

That is, the present invention provides a hydrogen production method comprising a gasification step of gasifying a first combustible material, and a gas treatment step of purifying a product gas generated in the gasification step to produce hydrogen. And a reforming step of mixing the composition gas obtained in the gasification step with a second combustible material to perform a reforming reaction of the second combustible substance, wherein the obtained reformed gas is subjected to the gas treatment step. It is decided to lead to.

The gas treatment step includes at least three steps of an exhaust heat recovery step, a gas cleaning step, and a transformation step. Alternatively, the three steps include a selective oxidation step, a carbon dioxide chemical absorption step, a methylation step, and a hydrogen purification step. And one or more of the carbon monoxide adsorption processes.

The product gas obtained by gasification of the first combustible material differs depending on the type of the first combustible material and the composition of the gasifying agent, but in general, hydrogen and carbon monoxide are a few percent to several tens percent, respectively, as fuel gas components. The main non-fuel gas components include carbon dioxide, nitrogen and argon as a few percent to tens of percent each, and trace amounts of acidic gas components include hydrogen sulfide and hydrogen chloride at several ppm. It is contained in concentrations ranging from to several thousand ppm. Also, regarding the water vapor content of the generated gas, when the first combustible material to be treated is general waste having a high water content or when water vapor is used as a gasifying agent, In this case, the water vapor content reaches 50% to 60%.

The temperature of the product gas is determined by the gasification temperature of the gasification process used.In recent years, in order to achieve complete decomposition of dioxin in the product gas and melting of fly ash in the incineration or gasification of waste, After the incineration process or the low-temperature gasification process, or independently, a high-temperature incineration process or a high-temperature gasification process is established, and the operating temperature in this process shall be in the range of 900 to 150 ° C. Many. However, this method is extremely effective in reducing the environmental burden, but on the other hand, it decreases the recovery efficiency when recovering energy from the first combustible material to be treated. This is because the generated gas has severe corrosiveness due to components such as hydrogen chloride, and it is technically difficult to recover and utilize the high-temperature thermal energy of the generated gas at high temperatures. .

On the other hand, when hydrogen gas obtained by gasification of combustibles is supplied as a fuel gas to a phosphoric acid type fuel cell or a polymer electrolyte fuel cell, the lowest possible carbon monoxide concentration is required. In the case of a fuel cell, the carbon monoxide must be below 100 ppm, preferably below 1 O ppm, more preferably below 1 ppm. In addition, since acidic gases, particularly hydrogen sulfide and hydrogen chloride, poison various gas absorbents, adsorbents and various catalysts in the gas treatment process in addition to the electrode catalyst of the fuel cell, lppm or less, preferably 0.1 ppm. It is necessary to remove it to 1 ppm or less. The higher the hydrogen content of the fuel gas supplied to the fuel cell, the better, but the dry gas must have a concentration of at least 40% (the same applies hereinafter).

The gas treatment step according to the present invention comprises: removing harmful components such as acid gas and carbon monoxide from the product gas obtained in the gasification step or the reformed gas obtained in the reformation step; Produces fuel gas suitable for fuel cells by separating all or part of inactive components such as carbon and nitrogen and increasing the hydrogen content The extent to which the carbon monoxide content should be reduced, and how high the hydrogen content should be, is determined by the type of fuel cell used, operating conditions, and design criteria. . On the other hand, the load of the gas treatment process is determined by the balance between the specifications of the hydrogen gas required by the fuel cell used and the composition of the generated gas or the reformed gas. For example, considering a case where a certain gasifying agent is used without adding the second combustible material, it is sufficient that the hydrogen content of the fuel cell used is 50% or more, and at the same time, 1 When the calorific value of the combustible is high, the load on the gas treatment process is small. Conversely, when pure hydrogen gas is required as hydrogen gas for the fuel cell used, and the first combustible material to be treated is general garbage and the calorific value is low, the load on the gas treatment process increases. Naturally, the higher the load of the gas treatment process, the higher the equipment cost of the process, and the higher the energy consumption, the lower the energy efficiency of the entire system, and as a result, the system itself is not established There is a risk.

Therefore, the effects listed below can be obtained by providing the reforming step in the present invention and injecting the second combustibles as needed.

1) The energy efficiency of the system can be enhanced by effectively utilizing the high-temperature thermal energy of the product gas obtained in the gasification process for the reforming reaction of the second combustibles to be input.

2) To simplify the gas treatment process and reduce the load by adjusting the hydrogen content and carbon monoxide content of the reformed gas by changing the type and amount of the second combustibles to be charged Can be.

3) — The method for producing hydrogen by gasification of a combustible material and the method for generating a fuel cell according to the present invention can be applied to a first combustible material having a low calorific value such as general garbage.

Thus, the present invention relates to a method for producing hydrogen and an energy method for generating fuel cells. Improve efficiency and improve economics.

Hereinafter, each step will be described in detail.

A) Gasification process

The gasification process of the present invention includes a one-stage gasification process using a high-temperature gasifier and a two-stage gasification process using a low-temperature gasifier and a high-temperature gasifier. It may be a process, but a two-stage gasification process is more desirable.

In the two-stage gasification process, the first combustible material consisting of waste and the gasifying agent for the low-temperature gasification furnace are supplied to the low-temperature gasification furnace, which is a fluidized bed gasification furnace, and the temperature is reduced from 400 ° C to 100 ° C. The substance undergoes thermal decomposition in the temperature range of 0 ° C, producing a gas containing hydrogen, carbon monoxide, and some hydrocarbons. In this case, the carrying temperature from the temperature at the time of charging to 400 ° C. to 100 ° C. is performed by partially burning the combustible material. Incombustibles mixed into the first combustible are discharged from the gasifier. As a gasification furnace, in addition to a fluidized-bed furnace, a roasted kiln, a single-stroke furnace, etc. may be used, but raw materials containing amorphous and non-combustible materials such as garbage can be used as first combustible materials. In this case, a fluidized bed furnace is more preferable. This is because in a fluidized bed furnace, unburned matter does not adhere to incombustible matter to be discharged from the furnace, so there are few problems in the treatment and disposal of incombustible matter. In addition, when a fluidized bed furnace is used, the bed temperature should be as low as possible without impairing thermal decomposition, specifically, if it is operated at a temperature between 400 ° C and 600 ° C, the incombustibles will oxidize. Since it is not used, it is easy to reuse and is preferable.

The product gas obtained in the low-temperature gasification furnace is supplied to the high-temperature gasification furnace together with the gasification agent for the high-temperature gasification furnace. It is further gasified at a temperature of from 1000 to 140 ° C., more preferably from 110 to 135 ° C., to reduce the molecular weight. The temperature of the high-temperature gasifier is maintained at a temperature higher than the temperature at which the ash contained in the generated gas melts, and 80 to 90% of the ash in the generated gas is converted into slag, which is then discharged outside the system as molten slag. Is discharged. Organic matter and hydrocarbons in the product gas are completely decomposed into hydrogen, carbon monoxide, steam, and carbon dioxide in the high-temperature gasifier.

The gasifying agent for the low-temperature gasification furnace used must have the amount of oxygen for partial combustion required to maintain the gasification temperature required for low-temperature gasification and supply gasification heat, and to fluidize It is only necessary to have a large amount of fluidizing gas, but a gasifying agent containing oxygen and water vapor as main components is desirable so as to reduce the load of the subsequent gas treatment step. Similarly, the high-temperature gasifying agent only needs to maintain the gasification temperature required for high-temperature gasification and the amount of oxygen for partial combustion required to supply the heat of gasification, but the load of the subsequent gas treatment process is limited. It is desirable to use a gasifying agent containing oxygen and water vapor as main components so as to reduce the amount. The oxygen-containing gas used for the low-temperature gasifying agent and / or the high-temperature gasifying agent may be air, but it may be an oxygen-enriched gas such as PSA oxygen (enriched oxygen produced by the pressure swing method) or liquid oxygen. Garlic is more desirable.

In addition, if the predetermined gasification temperature cannot be achieved in the high-temperature gasifier because the calorific value of the first combustible is too low, the auxiliary combustion material can be charged into the high-temperature gasifier. Any material may be used as the auxiliary material, as long as it generates a large amount of heat. A liquid fuel such as kerosene or heavy oil or a gaseous fuel such as city gas is preferable.

B) Reforming process

In the present invention, a reforming step is provided, and a high-temperature gasification product gas and a second combustible are supplied to the step to perform steam reforming of the second combustible. In addition to steam reforming, there are partial oxidation reforming and a combined method of partial oxidation reforming and steam reforming for combustibles. In the present invention, the temperature of the generated gas is extremely high. And the steam content is very high, so steam reforming is more advantageous. Examples of the second combustibles to be supplied include methane gas or digestive gas containing methane as a main component, city gas, propane gas, butane gas, and industrial gas containing these fuel components. Liquefied heaven Liquid fuels such as natural gas (LNG), gasoline, kerosene, isopropanol, ethanol and methanol; waste liquids containing these liquid fuels; solutions containing reformable organic components; and solids. Examples thereof include granular or powdered combustibles having a small amount of noncombustibles and ash.

In addition, the higher the calorific value of the first combustible material to be treated, the more preferable. Therefore, in the present invention, when the first combustible material is waste containing water such as general garbage, the first combustible material is used to increase the calorific value. To separate liquid components (so-called garbage juice). Then, the separated liquid component is evaporated and concentrated using the low-level waste heat generated by the method of the present invention, and the concentrated liquid component can be used as the second combustible. Further, in the case where a solid component containing almost no incombustibles or ash is mixed in the waste to be treated, the solid component can be selected and finely ground to be used as a second combustible. Of course, it is more preferable that the solid component is originally separated.

According to the present invention, if a liquid component and / or a solid component having a small amount of non-combustible and ash components are separated from the waste to be treated as described above, and are introduced into the reforming process as the second combustible material, not only waste but also gas The amount of the agent can also be reduced. As a result, since the amount of generated gas in the gasification step is reduced, the amount of combustion required to reach the predetermined gasification temperature of the generated gas is reduced, and the energy efficiency of the system is improved.

As an example, the following reaction formulas respectively show the steam reforming reactions when methane gas, methanol and fixed carbon are used as the second combustibles.

CH + H 20 → C 0 + 3 H 2 - 2 06 k J / mo 1 (1) CH 3 OH + H 2 O → C 02 + 3 H 2 - 1 3 1 k J / mo 1 (2) C + H ₂ 0 → CO + H 2-13 1 kJ / mo l (3) C + 2 H 20 → C 02 + 2 H 2 1 76 k J / mo 1 (4) (1) The steam reforming reaction of It proceeds at a temperature of 900 ° C, 900 ° C or higher without a reforming catalyst. In addition, the reaction is an endothermic reaction and requires 206 kJ of heat of reaction per mole of the monomer. Then, as the reaction proceeds, the sensible heat of the generated gas is utilized for the reaction heat, and the generated gas itself is cooled. Also, since steam participates in the reforming reaction as a reactant, the stoichiometric excess of steam is more advantageous in the reaction. Since the gas temperature of the present invention is high enough to reform the second combustible such as methane under conditions where no reforming catalyst is used, and the gas composition contains a large amount of water vapor, 2It can be said to be optimal for steam reforming of combustibles.

In addition, the steam reforming reaction of methanol shown in equation (2) proceeds at a temperature of 200 to 300 ° C. under the action of the reforming catalyst, and at a higher temperature without using a reforming catalyst. Therefore, it goes without saying that the method according to the present invention is also applicable to steam reforming of methanol.

The steam reforming reaction of fixed carbon shown in the equations (3) and (4) is a so-called water gas reaction, and proceeds at temperatures of 900 ° C or more and 700 ° C or more, respectively. Therefore, the method according to the present invention is also applicable to solid second combustibles containing fixed carbon.

Of course, a reforming catalyst may be used in the present invention. However, if a reforming catalyst is not required, the reforming reactor is simpler and the cost of the apparatus is lower.

It is advantageous to eliminate the need for a reforming catalyst by setting the temperature to 900 ° C. or higher. Therefore, the supply amount of the second combustible material, that is, the reaction amount of the reforming reaction may be determined so that the outlet temperature of the reforming reactor is about 900 ° C. The reforming reactor to be used only needs to have a volume that gives a sufficient residence time for the reforming reaction, and the reforming reactor and the rear part of the high-temperature gasifier can be integrated in design. When using a second combustible that undergoes steam reforming even in a relatively low temperature range, such as a sample, the temperature of the reformed gas at the outlet of the reforming reactor is as described above. It is good to be 300 ° C or more.

As shown in the above reaction formula (1), one mole of methane is reformed into three moles of hydrogen and one mole of carbon monoxide. In addition, carbon monoxide undergoes a further metamorphic reaction with steam in the subsequent metamorphosis step, producing one equivalent of hydrogen and one equivalent of carbon dioxide.As a result, it is possible to mix one mole of methane into the product gas. Thus, 4 moles of hydrogen and 1 mole of carbon dioxide, that is, a gas having a hydrogen content of 80% and a carbon dioxide content of 20% are mixed with the product gas. In other words, by introducing a second combustible such as methane gas into the reforming step to increase the hydrogen content of the reformed gas, nitrogen and argon which cannot be separated depending on the processing step to be applied. The content rate can be relatively reduced, which in turn can simplify the gas treatment process, reduce the load, improve efficiency and improve economic efficiency.

Depending on the time variation of the components of the first combustible used, it may not be necessary to temporarily add the second combustible.In addition, depending on the type of gasifying agent and fuel cell used, a reforming process is particularly provided. In some cases, these may not be necessary, but, of course, these cases are also included in the scope of the present invention.

C) Gas treatment process

In the present invention, by providing the reforming step, an optimal gas treatment step can be constructed according to the type and conditions of the first combustible material, the gasifier, and the fuel cell to be used. The gas treatment step according to the present invention comprises at least three steps: an exhaust heat recovery step, a gas cleaning step, and a metamorphosis step, or the three steps include a selective oxidation step, a carbon dioxide chemical absorption step, a methylation step, and hydrogen purification. One or more of the carbon monoxide adsorption steps are combined. Hereinafter, each of the constituent steps will be described in detail.

(1) Waste heat recovery process

In the present invention, an exhaust heat recovery step is provided to recover thermal energy from the reformed gas. And collect it. For example, a reformed gas of about 100 ° C. is led to a waste heat boiler, which generates high-pressure steam. The generated high-pressure steam drives the steam bin to increase the pressure of the gas after cleaning, which will be described later. In addition, a heat exchanger can be provided before or after the waste heat boiler to preheat the low-temperature gasifying agent and / or the high-temperature gasifying agent. Further, the low-pressure steam discharged from the steam turbine may be used as a steam source in a metamorphosis step or a heat source in a humidifier in a metamorphosis step, and / or as a heat source for regenerating the absorbent in the carbon dioxide chemical absorption step. Can also.

The reformed gas is cooled as a result of sensible heat recovery in this step. The lower the cooling temperature, that is, the lower the temperature I at the end of the process, the greater the amount of recovered heat. However, in order to avoid re-synthesis of dioxin in the gas cooling process after reforming, the temperature should be 400 ° C or higher, preferably 48 The temperature is preferably set to 0 ° C. or higher, more preferably 500 ° C. or higher.

(2) Cleaning process

In the present invention, a cleaning step is provided to remove an acid gas such as hydrogen sulfide or hydrogen chloride in the reformed gas to 10 ppm or less, preferably 1 ppm or less. As a gas cleaning method used in the cleaning step, there are a wet cleaning method and a dry cleaning method. In the wet cleaning method, the reformed gas is brought into contact with cleaning water in a cleaning tower to absorb and neutralize the acidic gas. The washing water may be pure water or water, but an alkaline solution obtained by adding 0.05 to 5% caustic soda to water is more preferable. When caustic soda solution is used as washing water, acid gas is absorbed and removed by the following neutralization reaction. Since dust in the reformed gas causes blockage of the gas flow path in the next step, it is washed and removed in this step.

H 2 S + Na 0 H → Na H S + H 2 O (5)

H C l + N a O H → N a C 1 + H 2 0 (6)

In the dry cleaning method, the reformed gas is brought into contact with the adsorbent in the adsorption tower before The acid gas is chemisorbed. The adsorption tower filled with the adsorbent may be either a fixed bed or a fluidized bed. As the adsorbent to be used, any solid substance having a large specific surface area and alkaline properties may be used, but a particulate metal oxide such as CaO or Zηθ is preferable. The adsorption reaction using C a 0 is shown in the following formula.

H. S + C a 0 → C a S + H ₂ 0 (7)

2 HC l + C a O → C a C 1 2 + H 2 0 (8)

(3) Metamorphosis process

In the present invention, a shift process is provided, and a shift reaction filled with a shift catalyst is carried out in the shift reaction described below, whereby carbon monoxide in the gas after washing is converted into hydrogen and carbon dioxide. To reduce CO to 1% or less, preferably 0.5% or less, more preferably 0.2% or less.

CO + H 2 O → C 0 ₂ + H ₂ (9) In the reaction, 1 equivalent of steam is consumed per C〇, so in the present invention, the steam component in the gas after washing is used as steam required for the reaction. I do. Since the above-mentioned transformation reaction is an exothermic reaction, lowering the reaction temperature lowers the equilibrium concentration of carbon monoxide.On the contrary, the reaction rate becomes slower, so the reaction temperature is in the range of 200 to 250 ° C. 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-mentioned temperature range include a Cu—Zn shift catalyst.

By the way, depending on the operation conditions and operation management of the cleaning step, a small amount of hydrogen sulfide may remain in the gas after cleaning. Hydrogen sulfide is used as an advanced desulfurization means to ensure that the hydrogen sulfide content of the gas after desulfurization is 1 ppm or less, and preferably 0.1 ppm or less, in order to prevent poisoning of the conversion catalyst in the shift process by hydrogen sulfide. It is desirable to provide a dry desulfurizer for adsorption removal.

The dry desulfurizer used in the present invention has a container filled with a desulfurizing agent. for Although the shape and the material of the container are not particularly limited, the shape is preferably cylindrical from the range of the gas temperature and the pressure, and the material is preferably stainless steel. The desulfurizing agent used is preferably an oxide such as iron oxide, zinc oxide or calcium oxide, or an adsorbent such as activated carbon, particularly activated carbon having an alkali agent supported on the surface. The shape of the desulfurizing agent is preferably granular, pellet, or honeycomb. The desulfurization reaction using zinc oxide is described below.

Z n 0 + H 2 S → Z n S + H ₂ 0 (1 0)

(4) Carbon dioxide chemical absorption process

In the present invention, a carbon dioxide chemical absorption step can be provided as one of the gas treatment steps after the washing step, the transformation step, or the selective oxidation step. In about該工, after cleaning gas or absorb separates only almost all or part of the transformer after the gas or the selective oxidation gas C 0 ₂ in accordance with the conditions required for the overall process. At the absorption tower of the step contacting the gas with absorbing liquid C 0 ₂ to absorb separation. As the absorbing solution, a thermocarbonated realm absorbing solution or an alminol olamine absorbing solution is preferable. In the step, an alkanol luminous absorbing solution having a strong absorbing ability is still more preferable. Examples of the absorbent include monoethanolamine (MEA), diethanolamine (DEA), and methylethanolamine (MDEA). The adsorption reaction using the alkanolamine absorption solution is described below.

R-NH 2 + H 2 O + CO 2 → R-NH ₃ HC 0 a (11) Since the above reaction is an exothermic reaction, the lower the absorption temperature, the better, but the temperature control is relatively easy. A range of ° C is preferred. Although the gas pressure is advantageously higher Needless to say, carried out at normal pressure to 7 atm ^{(1. 0 lxl 0 5 ~7.} 0 9 X 1 0 5 P a) of about the low-pressure region in the present invention. When the absorption liquid is absorbed and saturated, the absorption liquid is transferred to a regenerating tower, and the absorption liquid is transferred to 100 to 150 ° performs reproduction at a temperature of c, together with the recovery of co ₂ gas, returning the absorption liquid after regeneration in the absorption tower. As a heat source necessary for heating the absorbent during regeneration, low-pressure steam discharged from the steam bin in the heat recovery step is used. In addition, water vapor in the gas is removed by condensation in this step to the saturated vapor pressure at the absorption temperature. Note that acidic gases such as hydrogen sulfide and hydrogen chloride are further absorbed and removed in this step.

(5) Metanation process

In the present invention, a metanalysis step can be provided after the carbon dioxide absorption step as one of the gas treatment steps. After the absorption of carbon dioxide in this step, carbon monoxide in the gas is reduced to 10 ppm or less, preferably 1 ppm or less, and carbon dioxide in the gas is reduced to 100 ppm or less, preferably 10 ppm or less. β |] Then, the following methanation reaction (also referred to as a methanol reaction) is carried out in a converter packed with a methanation catalyst.

The hydrogen in the gas after conversion is used as the hydrogen required for the reaction. Since the above-mentioned reaction is an exothermic reaction, lowering the reaction temperature lowers the equilibrium concentration of carbon monoxide, but conversely lowers the reaction rate, so that the reaction temperature is 200 to 350 ° C. Is desirable. The type and shape of the catalyst are not limited as long as it promotes the metanation reaction, but nickel-based, iron-based, ruthenium-based methanation catalysts and the like are preferable.

In the case of providing a Metane one Chillon step, the C 0 ₂ removal limit C 0 ₂ remaining in front of carbon dioxide chemical absorption process in order to achieve the hydrogen concentration reduction due to load reduction and main evening Nation reaction Metaneshiyon step The concentration should be 1% or less, preferably 0.1% or less.

If a hydrogen purification step is provided after the methanation step, Since the water generated by the metalation reaction poisons the hydrogen storage alloy in the hydrogen purification process, dehumidifying means is installed to remove the water content to 100 ppm or less, preferably to 10 ppm or less. It is desirable to do. The dehumidifying means is not particularly limited, but is preferably a cooling condensing method, an adsorption method using a silica gel or activated alumina, or a method combining these methods.

(6) Hydrogen purification process

In the present invention, as one step of the gas treatment step, a hydrogen purification step can be provided after any of the following: the mes- sage step, the selective oxidation step, or the carbon monoxide adsorption step. The purpose of the hydrogen refining process is to use a hydrogen storage alloy to store only hydrogen from the gas after metanation or the gas after selective oxidation or the gas after adsorption of carbon monoxide, and to release the hydrogen once stored, thereby reducing the pressure. 1-1 0 atm ^{(1. 0 1 xl 0 5 ~} l. 0 1 X 1 0 6 P a), preferably 3-7 atm ^{(3. 0 4 xl 0 5 ~} 7. 0 9 xl 0 5 P a ) To produce pure hydrogen gas. In this step, nitrogen and argon of an inert gas which cannot be separated by other steps of the present invention can be separated. That is, H ₂ S and HC 1 which are the poisoning components of the hydrogen storage alloy are each 10 ppm or less, desirably lp pm or less, more desirably 0.1 lp pm or less, and CO is Ι ρ ρ ρ m or less, preferably below 1 ppm is, H ₂ 0 is 1 0 0 ppm or less, with respect to preferably rather were removed respectively below 1 0 ppm gas, provided the hydrogen purification steps with the hydrogen storage alloy, a hydrogen storage alloy of the gas Into the vessel containing hydrogen, and while absorbing the hydrogen into the hydrogen-absorbing alloy, occludes the hydrogen and separates N ₂ and Ar from the hydrogen.After saturation of the hydrogen-absorbing alloy, the nitrogen and argon are removed from the alloy vessel. After purging, the hydrogen storage alloy is heated to release hydrogen, so that hydrogen gas is pressurized and stored in a hydrogen tank, or supplied to a fuel cell power generation process via a hydrogen tank. . Nitrogen and argon in the released and purified hydrogen gas are removed to 100 ppm or less, respectively. Hydrogen concentration reaches 99.9% or more. Any hydrogen storage alloy may be used as long as it has a large hydrogen storage capacity, but a low-level exhaust heat of about 70 ° C generated from a phosphoric acid fuel cell or solid polymer fuel cell is used as a heating heat source when releasing hydrogen. as can be used as the hydrogen release pressure of 7 0 ° C in 1-1 0 atm ^{(1. 0 1 xl 0 5} ~ l. 0 1 x 1 0 6 P a), preferably 3-7 atm (3. ^{0 4 xl 0 5 ~ 7. 0} 9 xl 0 5 hydrogen storage alloy having a storage 'release properties of P a) is desirable, include L a N i 5 alloy and T i F e alloy specific alloys examples Can be 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 π + heat release (14) Hydrogen release reaction: La Ni ₅ «« → La Na i π + 3 Η ₂ + heat absorption (15) As shown in the above equation (14), 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. It is necessary to keep the storage temperature 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, as shown in the above equation (15), the hydrogen release reaction is an endothermic reaction. Therefore, 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 suck is used, and in the embodiment in which the fuel cell power generation step is not provided. Uses steam or hot water recovered in processes such as gasification process and exhaust heat recovery process. 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 above-described hydrogen storage alloy is used to continuously store and release hydrogen. At least two hydrogen storage alloy storage containers are provided, and switching is performed by a solenoid valve.

(7) Selective oxidation process In the present invention, a selective oxidation step can be provided after the shift step as one of the gas treatment steps. The purpose of this step is to adopt a solid polymer fuel cell in the fuel cell power generation step, and to adjust the concentration of carbon monoxide in the hydrogen-containing gas supplied to the fuel cell to lOO ppm or less, preferably lO ppm or less. It is to lower to. That is, the following selective oxidation reaction is performed by supplying oxygen or air while guiding the gas to the selective oxidizer filled with the selective oxidation catalyst.

C 0 + 1/20 ₂ → C 0> (1 6)

The larger the amount of oxygen supplied to the reaction, the lower the residual concentration of carbon monoxide. Therefore, it is desirable that the amount of carbon monoxide be at least 2 equivalents. Further, the reaction temperature is preferably in the range of 100 to 180 ° C, and any catalyst may be used as long as it has excellent selective oxidation property to carbon monoxide and a high reaction rate. A gold catalyst in which gold is supported on a carrier is suitable.

(8) C0 adsorption process

In the present invention, a carbon monoxide adsorption step can be provided after the carbon dioxide absorption step as one of the gas treatment steps. The purpose of this step is to use a polymer electrolyte fuel cell in the fuel cell power generation step, and to reduce the concentration of carbon monoxide in the hydrogen-containing gas supplied to the fuel cell to 100 ppm or less, preferably 100 m2. Below, more preferably, it is reduced to 1 ppm or less. That is, a carbon monoxide adsorption step by a pressure swing adsorption (PSA) method is provided, and the gas is introduced into an adsorption tower filled with a C〇 adsorbent to adsorb and separate C 0 in the gas. In order to maximize the adsorption capacity of the adsorption tower for C 0, it is desirable to fill the adsorption tower with an adsorbent that exhibits selective adsorption to CO. That is, the suction force for CO as the adsorbent is relatively strong, while the C 0 _2, N may be any adsorption force weak adsorbent for ₂及beauty A r, for example Zeorai Tomo Rekiyura one sheet one ugly or carbon molecular Sieves or activated carbon or activated alumina are preferred, and are described above by agents that have an affinity for C0. A c0 selective adsorbent having a modified adsorbent is more preferred. The lower the adsorption temperature is, the more advantageous it is, but the temperature is preferably in the range of 12 to 40 ° C. where the temperature control is relatively easy. Although the gas pressure is of course higher Advantageously, the have us in the present invention is carried out at atmospheric pressure to 7 atm ^{(1. 0 1 xl 0 5} ~ 7. 0 9 xl 0 5 P a) of about the low-pressure region . When the adsorbent used is adsorbed and saturated, desorption is performed under reduced pressure by a vacuum pump, and the desorbed C0 purge gas is returned to the shift process. As the desorption pressure is reduced by the vacuum pump, the pressure difference between the adsorption pressure and the desorption pressure increases, so that the treatment capacity of the adsorption tower is improved.On the other hand, the power consumption of the vacuum pump increases, so the desorption pressure is increased. The range of 100/760 to 10 / 760Pa (100 to 10Torr) is desirable.

(D) Fuel cell power generation process

The present invention provides a fuel cell power generation step, and supplies hydrogen gas produced by the hydrogen production method as a fuel gas to the fuel cell power generation step to generate power. Since the temperature of the pure hydrogen gas or hydrogen-containing gas produced in the gas treatment process in the hydrogen production method is relatively low, the hydrogen concentration is high, and the content of carbon monoxide is low, the temperature of the fuel cell used is relatively low. An operating phosphoric acid fuel cell, especially a polymer electrolyte fuel cell, is preferred. The cell reaction in the case of a phosphoric acid type or solid polymer type fuel cell is described below.

Anodic _{^{reaction: H 2 → 2 H + +}} 2 e - (1 7) force Sword _{reaction: 1/20 2 + 2 H} + + 2 e → H 2 0 (1 8) That is, the fuel cell static hydrogen gas Tsu Air or oxygen-enriched air or oxygen gas is supplied to the cathode electrode chamber of the cathode and the cathode electrode chamber, respectively, and power is generated by the above-described battery reaction. The operating temperatures of the phosphoric acid fuel cell and the polymer electrolyte fuel cell are around 200 ° C. and around 80 ° C., respectively. Requires the stack to cool. In the embodiment in which the hydrogen purification step of the present invention is provided, the screen cooling water is burned. By circulating between the fuel cell power generation process and the hydrogen refining process using a hydrogen storage alloy, the exhaust heat of the screen is used as a heating source when releasing hydrogen.

As a matter of course, the reformed gas obtained by the method of the present invention is processed in a gas processing step to produce a fuel gas, and the produced fuel gas is melted in a carbonate fuel cell (MCFC) or a solid oxide fuel cell. It can also be supplied to a fuel cell (SOFC) to generate electricity. In this case, the gas treatment step can be constituted by at least a gas cleaning step, or a combination of the gas cleaning step and the exhaust heat recovery step and / or the metamorphosis step. In this case, a dry cleaning method can be employed in the gas cleaning step. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an explanatory diagram of a hydrogen production method and a fuel cell power generation method according to the present invention.

FIG. 2 is an explanatory diagram of the gas treatment step according to the present invention.

FIG. 3 is an explanatory diagram of the hydrogen production method and the fuel cell power generation method according to the first embodiment of the present invention.

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

FIG. 5 is an explanatory diagram of a hydrogen production method and a fuel cell power generation method according to a third embodiment of the present invention.

FIG. 6 is an explanatory diagram of a hydrogen production method and a fuel cell power generation method according to a fourth embodiment of the present invention.

FIG. 7 is an explanatory diagram of a hydrogen production method and a fuel cell power generation method according to a fifth embodiment of the present invention.

FIG. 8 is a view showing a first embodiment of an apparatus for performing the gasification step of the present invention. FIG. 9 is a view showing a second embodiment of the apparatus for performing the gasification step of the present invention.

FIG. 10 is a diagram showing a typical configuration of main components of the second embodiment of the present invention.

FIG. 11 is a view showing a third embodiment of the apparatus for performing the gasification step of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of a method for producing hydrogen by gasifying combustibles and a method for generating a fuel cell according to the present invention will be described with reference to FIGS. 1 to 7, the same or corresponding steps or members are denoted by the same reference numerals, and overlapping description will be omitted.

FIG. 1 is a schematic diagram showing a hydrogen production method and a fuel cell power generation method of the present invention. In the hydrogen production method of the present invention, as shown in FIG. 1, first, a first combustible substance a is gasified using a gasifying agent b in a gasification step A, and the obtained product gas c and a second combustible substance are obtained. e into the reforming step B, and the second combustible e is subjected to water vapor reforming, and the resulting reformed gas f is led to the gas treatment step C for pure hydrogen gas g or hydrogen-containing gas. to produce h. Further, the pure hydrogen gas g or the hydrogen-containing gas h produced by the above-described hydrogen production method is supplied as fuel gas to the fuel cell power generation step D to generate power.

The configuration of the gas treatment step C differs depending on the embodiment. The configuration according to each embodiment is shown in FIG. As shown in the figure, the gas treatment step C of the present invention comprises: an exhaust heat recovery step 1 for recovering thermal energy from the reformed gas f; a gas cleaning step 2 for removing hydrogen sulfide and hydrogen chloride; Gas conversion step 3, gas cleaning step 2, or conversion step 3 or selective oxidation step 7 for converting carbon monoxide into hydrogen and carbon dioxide Is a carbon dioxide chemical absorption process in which almost all or only part of the carbon dioxide in the gas after conversion or the gas after selective oxidation is absorbed and separated4.The carbon monoxide and carbon dioxide in the gas after carbon dioxide absorption 5 or methanation step 5 or selective oxidation step 7 or carbon monoxide adsorption step 8 Pure hydrogen gas is produced by storing only hydrogen from the gas after carbon monoxide adsorption and then releasing hydrogen to provide pure hydrogen gas after the hydrogen purification process 6 and the conversion process 3 to selectively oxidize carbon monoxide It is constituted by a combination of a carbon monoxide adsorption step 8 provided after the selective oxidation step 7 and the carbon dioxide chemical absorption step 4 to adsorb and separate carbon monoxide.

The exhaust heat recovery step 1 is performed by a heat exchanger, etc., the gas cleaning step 2 is performed by a cleaning tower, the shift step 3 is performed by a shift converter, and the carbon dioxide chemical absorption step 4 is performed by an absorption tower. In addition, the methanation step 5 is performed in a metanalysis reactor, the hydrogen purification step 6 is performed in a hydrogen storage alloy container, the selective oxidation step 7 is performed in a selective oxidizer, and the carbon monoxide absorption step 8 is performed in an adsorption tower.

The gas processing equipment is equipped with one or more other equipment (absorption tower, methanation reactor, selective oxidizer, adsorption tower) in the heat exchanger, washing tower, transformer, hydrogen storage alloy container and the above-mentioned process. It is a combination according to.

The following specifically describes an embodiment in which general-purpose garbage is used as the first flammable substance, a mixed gas of PSA oxygen and water vapor is used as the gasifying agent, and city gas is used as the second flammable substance. I do.

In the first embodiment, a phosphoric acid fuel cell is used as the fuel cell, and the first combustible material in the case where the required hydrogen content is 50% or more and the CO content is 0.5% or less is required as the fuel gas specification. Hydrogen production method by gasification and fuel cell generation It is an electricity method. In the configuration of the first embodiment, as shown in FIG. 3, in the gasification step A, the first combustible material a is gasified using the gasifying agent b, and the resulting product gas c and the second combustible material e is introduced into the reforming step B, and the second combustible e is subjected to water vapor reforming. Here, the amount of the second combustible material e (city gas) to be supplied is determined so that the hydrogen content of the hydrogen-containing gas h obtained in the metamorphosis step 3 described later is 50% or more. Next, the reformed gas f obtained in the reforming process B is led to the exhaust heat recovery process 1 to perform heat recovery, then introduced into the gas cleaning process 2, and then supplied to the conversion process 3 after the cleaning. A shift reaction is performed to produce a hydrogen-containing gas h. Then, the produced hydrogen-containing gas h is supplied to the phosphoric acid type fuel cell in the fuel cell power generation step D to generate electric power. This method is advantageous in terms of equipment cost and internal power consumption because the process is simple, but on the other hand, the power generation efficiency of the fuel cell is relatively low due to the low hydrogen content of the supplied hydrogen-containing gas h, and the type of fuel cell Is disadvantageous in that it is limited to the phosphoric acid type which has relatively strong C 0 resistance.

In the second embodiment, a polymer electrolyte fuel cell is used as the fuel cell, and the required specification of the fuel gas is a combustible gas when the hydrogen content is 50% or more and the C0 content is 10 ppm or less. It is a method for producing hydrogen by gasification and a method for generating fuel cells. In the configuration of the second embodiment, as shown in FIG. 4, in the gasification step A, the first combustible substance a is gasified using the gasifying agent b, and the obtained product gas c and the second combustible substance e Into the reforming step B to perform steam reforming of the second combustible e. Here, the amount of the second combustible material e (city gas) to be supplied is determined so that the hydrogen content of the hydrogen-containing gas h obtained in the selective oxidation step 7 described later becomes 50% or more. Next, the reformed gas f obtained in the reforming step B is led to the exhaust heat recovery step 1 to perform heat recovery, and then introduced into the gas cleaning step 2, and then the post-cleaning gas is supplied to the conversion step 3 to perform a conversion reaction. After performing the above, carbon monoxide is selectively oxidized in a selective oxidation step 7 to produce a hydrogen-containing gas h. Then, the produced hydrogen-containing gas h is separated from the solid Power is supplied to the secondary fuel cell to generate electricity. The method is advantageous in terms of equipment cost and in-house power consumption because the process is simple, but is disadvantageous in that the hydrogen content of the supplied hydrogen-containing gas h is low and the fuel cell power generation efficiency is relatively low. The method of the second embodiment is more advantageous than the method of the first embodiment in that it can be applied to a polymer electrolyte fuel cell, which is considered to be more economical. In the third embodiment, a polymer electrolyte fuel cell is used as a fuel cell, and the required specification of the fuel gas is a combustible gas when the hydrogen content is 60% or more and the C0 content is 10 ppm or less. It is a method for producing hydrogen by gasification and a method for generating fuel cells. In the configuration of the third embodiment, as shown in FIG. 5, in the gasification step A, the first combustible material a is gasified using the gasifying agent b, and the obtained product gas c and the second combustible material e Into the reforming step B to perform steam reforming of the second combustible e. Here, the amount of the second combustible material e (city gas) to be supplied is determined so that the hydrogen content of the hydrogen-containing gas h obtained in the selective oxidation step 7 described later is 60% or more. Next, the reformed gas f obtained in the reforming process B is led to the exhaust heat recovery process 1 to perform heat recovery, and then introduced into the gas cleaning process 2, and then the post-cleaning gas is passed through the carbon dioxide chemical absorption process 4 Then, the mixture is supplied to a shift process 3 to perform a shift reaction, and further a selective oxidation process 7 is performed to produce a hydrogen-containing gas h. If C 0 ₂ removal rate of carbon dioxide chemical absorption step 4 set watching the hydrogen concentration of the first combustible materials a and second combustibles e hydrogenous gas h obtained at a feed rate and selective oxidation step 7 of Good. Then, the produced hydrogen-containing gas h is supplied to the polymer electrolyte fuel cell in the fuel cell power generation step D to generate electric power. The method of the third embodiment has one additional step compared to the method of the second embodiment, which is disadvantageous in terms of equipment cost and in-house power consumption, but the hydrogen content of the supplied hydrogen-containing gas h is low. Relatively high is advantageous in that the hydrogen utilization rate and fuel cell power generation efficiency are relatively high, and the operation of the fuel cell is shifted to a safe side. The fourth embodiment uses a polymer electrolyte fuel cell as a fuel cell, The required specifications for hydrogen include a hydrogen production method by gasification of combustibles and a fuel cell power generation method when the hydrogen content is 70% or more and the C◦ content is 5 ppm or less. In the configuration of the fourth embodiment, as shown in FIG. 6, in the gasification step A, the first combustible material a is gasified using the gasifying agent b, and the resulting product gas c and the second combustible material e Into the reforming step B to perform steam reforming of the second combustible e. Here, the upper limit of the amount of the second combustible material e that can be supplied is that the outlet temperature of the reforming step B is equal to or higher than the reformable temperature of the second combustible material e (in the case of city gas, 900 ° C or more without a catalyst, (Preferably 100 ° C. or more, more preferably 1100 ° C. or more). The actual supply amount may be determined by checking the hydrogen concentration after gas treatment. Next, the reformed gas f obtained in the reforming step B is led to the exhaust heat recovery step 1 to perform heat recovery, and then introduced into the gas cleaning step 2, and then the gas after cleaning is supplied to the conversion step 3. After the metamorphic reaction, the gas after the metamorphosis is led to the carbon dioxide chemical absorption step 4 to separate and remove C 0 to 1% or less, preferably 0.5% or less. Then, by supplying carbon dioxide absorption after gas Metaneshi tio down step 5 to methanation of residual CO and C_〇 ₂ in the gas to produce a hydrogen-containing gas h. Then, the produced hydrogen-containing gas h is supplied to the polymer electrolyte fuel cell in the fuel cell power generation step D to generate electric power. The method of the fourth embodiment is slightly disadvantageous in terms of equipment cost and in-house power consumption because the load of the carbon dioxide absorption step 4 is larger than that of the method of the third embodiment. Higher hydrogen content and lower residual CO concentration have relatively high hydrogen utilization and fuel cell power generation efficiency, and are advantageous in that fuel cell operation can be shifted to safer sites. .

In the fifth embodiment, a polymer electrolyte fuel cell is used as the fuel cell, and the first specification when the hydrogen content is 99.9% or more and the CO content is 0.5 pm or less is required as a fuel gas specification. A hydrogen production method by gasifying combustibles and a fuel cell power generation method. In the configuration of the fifth embodiment, FIG. As shown, in the gasification step A, the first combustible substance a is gasified using the gasifying agent b, and the resulting product gas c and the second combustible substance e are introduced into the reforming step B, Performs steam reforming of combustibles e. Here, the upper limit of the amount of the second combustible material e that can be supplied is that the outlet temperature of the reforming step B is equal to or higher than the reformable temperature of the second combustible material e. (Preferably 100 ° C. or more, more preferably 1100 ° C. or more). The actual supply amount may be determined by checking the hydrogen concentration after gas treatment. Next, the reformed gas f obtained in the reforming step B is led to the exhaust heat recovery step 1 to perform heat recovery, and then introduced into the gas cleaning step 2, and then the gas after the cleaning is supplied to the conversion step 3 for conversion. the reaction carried out, the modified gas after carbon dioxide chemical absorption step 4 led to C 0 ₂ 1% or less, preferred properly is 0. separating off 5% or less. Then, the gas after the carbon dioxide absorbed by supplying the main evening Nesho down step 5 the residual C 0 and C 0 ₂ in the gas and methane reduction, pure hydrogen gas introduced into a hydrogen purification step 6 after dehumidifying methanation gas after to produce g. Then, the produced pure hydrogen gas g is supplied to the polymer electrolyte fuel cell in the fuel cell power generation step D to generate electric power. The method of the fifth embodiment is more complicated than the method of the fourth embodiment, which is disadvantageous in terms of equipment cost and in-house power consumption. However, since pure hydrogen gas g is supplied, the hydrogen utilization rate is 10%. This is advantageous because it is close to 0%, and the fuel cell power generation efficiency is high and the life of the fuel cell is extended.

Table 1 summarizes the preconditions and features of Embodiments 1 to 5.

【table 1 】

Next, details of the gasification step of the present invention will be described with reference to FIGS.

FIG. 8 is a view showing a first embodiment of an apparatus for performing the gasification step of the present invention. As shown in Fig. 8, the first combustible material a supplied from the raw material feeder 101 to the gasification furnace 102, which is a fluidized-bed gasification furnace, is in a temperature range of 900 to 1200 ° C. It undergoes thermal decomposition to produce product gas c containing hydrogen and carbon monoxide, which are active gas components for fuel cell power generation, and product gas c is sent to reformer 300 along with second combustible e. . In this case, the temperature of the gasifier is maintained by partially burning the first combustible a. If the temperature of the reformer 300 is not sufficient, oxygen may be supplied to the reformer 300 to raise the temperature by partial combustion, but the object of the present invention is to increase the temperature of the generated gas by high temperature. Using heat Since the second combustible e is to be reformed, it is better not to supply oxygen to the reformer 300 as much as possible. Incombustibles d mixed into the first combustibles a are discharged from the gasifier 102. A rotary kiln, a single-stroke furnace, etc. may be used for the gasification furnace in addition to a fluidized bed furnace. In such cases, a fluidized bed furnace is preferred. This is because in a fluidized bed furnace, unburned matter does not adhere to incombustible matter to be discharged from the furnace, so there are few problems in treating and disposing of incombustible matter.

FIG. 9 is a diagram showing a second embodiment of an apparatus for performing a gasification step including two-stage gasification of low-temperature gasification and high-temperature gasification. The first combustible material a is 400 to 100 000 in the low-temperature gasification furnace 102. The product gas obtained by pyrolysis and gasification at preferably 450 to 800 ° C, more preferably 500 to 600 ° C, is directly sent to the high-temperature gasification furnace 115. In the high-temperature gasification furnace 115: 900 to: L500 ° C, preferably 100 to 140 ° C, more preferably 110 to 140 ° C At a temperature of 0 ° C, it is further gasified and reduced in molecular weight. The temperature of the high-temperature gasifier 1 15 is maintained at a temperature higher than the temperature at which the ash contained in the generated gas melts, and 80 to 90% of the ash in the generated gas is turned into slag, which is used as molten slag k. It is discharged outside.

In the second embodiment, the second combustible e can be supplied to any location as long as it is downstream of the slag discharge outlet of the high-temperature gasifier 115, but it is as close as possible to the slag discharge outlet in order not to make the device excessively large. Is more desirable. In Fig. 9, a reformer 300 is provided downstream of the high-temperature gasifier 1 15 in addition to the high-temperature gasifier, but the high-temperature gasifier 1 1 after the supply point of the second combustible material e If the gas residence time in (5) is sufficient as the reforming time for the second combustible e, the organic matter and hydrocarbons in the product gas, including the components of the second combustible e, are completely hydrogenated in the high-temperature gasification furnace. It is decomposed into carbon dioxide, steam, and carbon dioxide, so of course the reformer It is not necessary to provide 300 and can be omitted.

The post-reformation gas f after complete decomposition of organic matter and removal of solid content is sent to the gas treatment step C described above. In the gasification process shown in Fig. 9, the high-temperature gasification furnace 1 15 performs three functions: complete decomposition of dioxin, fuel reforming, and slagging of ash. This process has the great advantage that ash can be slagged, and the ash can be taken out separately from alkali metal salts and low-melting metals, thus reducing the ash disposal problem.

FIG. 10 shows a typical configuration of the main components of the second embodiment shown in FIG. The low-temperature gasification furnace 102 is a cylindrical fluidized-bed furnace having an internal swirling flow, and performs stable gasification by increasing the diffusivity of the raw material in the furnace. By supplying a fluidizing gas containing no oxygen to the center of the furnace where the fluidized medium is settled, and supplying a gasifying gas containing oxygen only to the periphery of the furnace, The selective combustion of the char generated in the furnace becomes possible, contributing to the improvement of carbon conversion rate and cold gas efficiency. The high-temperature gasifier 1 15 is a rotary melting furnace.

The cylindrical fluidized bed furnace shown in FIG. 10 will be described in detail below. A conical dispersion plate 106 is arranged on the hearth of the cylindrical fluidized-bed furnace. The fluidizing gas supplied through the dispersion plate 106 is supplied to the central fluidizing gas 207 supplied upward from the vicinity of the central part 204 of the furnace bottom into the furnace and the peripheral part 203 of the furnace bottom. From the peripheral fluidizing gas 208 supplied as an upward flow into the furnace. The central fluidizing gas 207 is made of a gas containing no oxygen, and the peripheral fluidizing gas 207 is made of a gasifying agent containing oxygen. The oxygen content of the fluidized gas as a whole should be 10% or more and 30% or less of the theoretical combustion oxygen required for combustible combustibles, and the inside of the furnace is a reducing atmosphere.

The mass velocity of the central fluidizing gas 207 is made smaller than that of the peripheral fluidizing gas 208, and the upward flow of the fluidizing gas above the periphery in the furnace is differential. By Lek Yu 206, he is turned to the center of the furnace. As a result, a moving bed 209 in which the fluidized medium (using silica sand) settles and diffuses is formed in the center of the furnace, and a fluidized bed in which the fluidized medium is actively fluidized around the furnace. 0 is formed. The fluidized medium rises in the fluidized bed 210 around the furnace, as shown by the arrow 1 18, is then turned by the deflector 206, and flows above the moving bed 209, By descending in the moving bed 209 and then moving along the dispersion plate 106 as shown by the arrow 112, it flows below the fluidized bed 210, whereby the fluidized bed 210 And the moving bed 209 circulates as indicated by the arrows 1 18 and 1 12.

The first combustible material a supplied to the upper part of the moving bed 209 by the raw material feeder 101 is moved down in the moving bed 209 together with the flowing medium by the heat of the flowing medium. It is heated and mainly volatiles are gasified. Since there is no or little oxygen in the moving bed 209, the pyrolysis gas (product gas) composed of the gasified volatiles is not burned and passes through the moving bed 209 as indicated by the arrow 116. The moving bed 209 therefore forms a gasification zone G. The product gas that has moved to the freeboard 107 rises as shown by the arrow 120 and is discharged as a product gas j from the gas outlet 108 through the freeboard 107.

The gas (fixed carbon) and evening gas, which are not gasified in the moving bed 209, flow from the lower part of the moving bed 209 together with the fluidized medium to the peripheral part of the furnace as indicated by the arrow 112. It moves to the lower part of the layer 210 and is burned by the peripheral fluidizing gas 208 having a relatively high oxygen content and partially oxidized. The fluidized bed 210 forms an oxidation zone S for combustibles. In the fluidized bed 210, the fluidized medium is heated by the heat of combustion in the fluidized bed and becomes a high temperature. The high temperature fluid medium is reversed by the inclined wall 206 as shown by the arrow 118, moves to the moving bed 209, and again becomes a heat source for gasification. The temperature of the fluidized bed is 40 0 to: Maintained at L 0000 ° C, preferably 400 to 600 ° C, so that the suppressed combustion reaction can be continued. A ring-shaped non-combustible material discharge port 205 for discharging non-combustible material is formed in a portion on the outer peripheral side of the bottom of the fluidized-bed gasification furnace.

According to the fluidized-bed gasification furnace shown in Fig. 10, a gasification zone G and an oxidation zone S are formed in the fluidized-bed furnace, and the fluidized medium serves as a heat transfer medium in both zones. In G, high-quality combustible gas having a high calorific value is generated, and in the oxidation zone S, it is possible to efficiently burn char and tar which are difficult to gasify. Therefore, the gasification efficiency of combustibles such as waste can be improved, and high-quality product gas can be generated. The low-temperature gasification furnace is not limited to the cylindrical fluidized-bed furnace, and may be a kiln-stalker furnace as in the previous embodiment.

Next, the rotary melting furnace will be described. Rotating melting furnace as high temperature gasifier 1 1 5 The cylindrical melting chamber 1 1 5 a with a vertical axis and the secondary gasifier 1 1 5 slightly inclined from the horizontal b, and a tertiary gasification chamber 115c with a substantially vertical axis arranged downstream of it. There is a slag discharge port 142 between the secondary gasification chamber 1 15b and the tertiary gasification chamber 1 15c, where most of the ash is discharged as slag. The product gas supplied to the swirling melting furnace is supplied tangentially so as to generate a swirling flow in the primary gasification chamber 115a. The inflowing product gas forms a swirling flow, and the solid content in the gas is trapped on the surrounding wall by centrifugal force, so the slag conversion rate and slag collection rate are high, and the slag mist is less scattered. is there.

A gasifying agent b containing oxygen is supplied from a plurality of nozzles 1 34 in the swirling melting furnace so as to maintain an appropriate temperature distribution in the furnace. Completely decompose hydrocarbons and turn ash into slag in the primary gasification chamber 1 15a and the secondary gasification chamber 1 15b. Adjust the temperature distribution to complete. Since the supply of oxygen alone may cause burning of the nozzle, etc., a gasifying agent b obtained by diluting oxygen with steam or the like is used. In addition, steam must be supplied so as not to be insufficient because it contributes to the reduction of hydrocarbon molecules by steam reforming. This is because the temperature inside the furnace is high, and if the water vapor is insufficient, the condensation polymerization reaction will produce extremely poorly-reactive graphite, leading to unburned loss.

The slag flows down the lower surface of the secondary gasification chamber 1 15 b and is discharged from the slag discharge port 142 as molten slag k. The tertiary gasification chamber 115c serves as an interference zone for preventing the slag discharge outlet 142 from being cooled by the radiant cooling from the waste heat boiler in the reforming process B provided downstream At the same time, it is provided for the purpose of completing the reduction of the molecular weight of undecomposed gas. An exhaust port 144 for exhausting the generated gas c is provided at the upper end of the tertiary gasification chamber 115c, and a radiation plate 148 is provided at the lower portion. The radiation plate 144 has a function of reducing the amount of heat lost from the exhaust port 144 due to radiation. Reference numeral 13 2 denotes a starter wrench, and reference numeral 13 6 denotes an auxiliary burner wrench. Organic matter and hydrocarbons in the generating power are completely decomposed into hydrogen, carbon monoxide, steam, and carbon dioxide in the high-temperature gasifier. The generated gas c obtained in the high temperature gasifier 1 15 is discharged from the exhaust port 144 and sent to the reforming step B. The high-temperature gasifier is not limited to the rotary melting furnace, but may be another type of gasifier.

FIG. 11 is a view showing a third embodiment of the apparatus for performing the gasification step of the present invention. Figure 11 shows a high-temperature gasifier with a shape that is advantageous for slag discharge. That is, the high-temperature gasifier 115 is configured as a two-stage upper and lower stage, and the generated gas flows in from the upper side of the high-temperature gasifier 115 and flows to the lower side. In this case, since the gas also flows in the direction in which the slag falls due to gravity, the flow is natural, and there is little blockage trouble at the slag discharge port. In addition, high temperature gasification A reformer 300 can be installed on the lower side of the furnace 1 15. In this case, since the reformer 300 must withstand the slag flow, it is impossible to install a catalyst packed bed, etc., and it can only provide a high-temperature field. When supplying e, it is important to devise measures such as supplying a swirling flow in the reformer 300 so that it can be sufficiently mixed with the high-temperature generated gas from the high-temperature gasifier 115. . Further, a waste heat boiler 119 composed of a radiation boiler is installed below the reformer 300. The reformed gas f is sent to the gas treatment step C via the waste heat boiler 119. The molten slag k is discharged outside the furnace through a waste heat boiler 1 19. Other configurations are the same as those of the second embodiment shown in FIG.

As described above, according to the present invention, the energy efficiency of the system can be improved, the concentration and flow rate of hydrogen gas supplied to the fuel cell can be stabilized, and the applicable gas can be improved. The degree of freedom can be given to the process and the design and selection of the fuel cell. That is, according to the present invention, a combustible substance is gasified or reformed, and a hydrogen gas suitable for fuel cell power generation can be produced from the generated gas at low cost and high efficiency. Then, fuel cell power generation can be efficiently performed using the produced hydrogen gas. Industrial applicability

The present invention relates to an energy conversion technique for converting chemical energy of combustibles into electric energy with high efficiency. The present invention relates to a method of gasifying or reforming combustible materials such as combustible waste and coal to produce hydrogen gas from a generated gas, and a method of generating electricity by supplying the produced hydrogen gas to a fuel cell. It can be used for power generation systems that generate hydrogen by using the produced hydrogen gas as fuel gas for fuel cells.

Claims

The scope of the claims

1. A hydrogen production method comprising: a gasification step of gasifying a first combustible material; and a gas treatment step of purifying a product gas generated in the gasification step to produce hydrogen.

A reforming step of mixing the generated gas obtained in the gasification step with a second combustible to perform a reforming reaction of the second combustible is provided, and the obtained reformed gas is guided to the gas processing step. A method for producing hydrogen by gasifying combustibles.

2. The gasification step has a gasification temperature range of 900 to 150 ° C., the temperature of the product gas obtained from the gasification step is 900 ° C. or higher, and water as a composition. The method for producing hydrogen by gasifying a combustible material according to claim 1, wherein the method includes steam, hydrogen, and / or carbon monoxide.

3. The gasification step comprises a two-stage gasification step of a low-temperature gasification step and a high-temperature gasification step, and the gasification temperature of the high-temperature gasification step is 900 to 150 ° C. The flammable substance according to claim 1, wherein the temperature of the product gas obtained from the high-temperature gasification step is 900 ° C or more, and the composition contains steam, hydrogen, and / or carbon monoxide. Hydrogen production method by gasification.

4. A combustible gas according to claim 2 or 3, characterized in that a combustion aid can be added to the gasification step according to claim 2 or the high-temperature gasification step according to claim 3. Hydrogen production method by chemical conversion.

5. The gas treatment step is composed of at least three steps: an exhaust heat recovery step, a gas cleaning step, and a metamorphosis step, or the three steps include a selective oxidation step, a carbon dioxide chemical absorption step, and a 5.Hydrogen by combustible gasification according to any one of claims 1 to 4, characterized by combining one or more of a process, a hydrogen purification process, and a carbon monoxide adsorption process. Production method.

6. A combustible material provided with a fuel cell power generation step, wherein hydrogen gas produced by the method according to any one of claims 1 to 5 is supplied as fuel gas to the fuel cell power generation step to generate power. Cell power generation method by gasification of fuel.

7. The fuel cell power generation method according to claim 6, wherein the fuel cell used in the fuel cell power generation step is a polymer electrolyte fuel cell or a phosphoric acid fuel cell.

8. A hydrogen production apparatus comprising: a gasification furnace for gasifying the first combustible material; and a gas processing apparatus for purifying generated gas generated in the gasification furnace to produce hydrogen,

Providing a reforming device for mixing the generated gas obtained in the gasification furnace with a second combustible to perform a reforming reaction of the second combustible; and guiding the obtained reformed gas to the gas processing device. An apparatus for producing hydrogen by gasifying combustibles.

9. The gasification furnace has a gasification temperature range of 900 to 150 ° C., the temperature of the generated gas obtained from the gasification furnace is 900 ° C. or higher, and the composition is steam and 9. The apparatus for producing hydrogen by gasifying combustibles according to claim 8, comprising hydrogen, hydrogen and / or carbon monoxide.

100. The gasifier comprises a low-temperature gasifier and a high-temperature gasifier, and the high-temperature gasifier has a gasification temperature range of 900 to 150 ° C. 9. The hydrogen production by gasifying combustibles according to claim 8, wherein the temperature of the produced gas obtained is 900 ° C. or higher, and the composition contains steam and hydrogen and / or carbon monoxide. apparatus.

11. A combustible material characterized by providing a fuel cell and supplying hydrogen gas produced by the device according to any one of claims 8 to 10 as a fuel gas to the fuel cell to generate power. Fuel by gasification IE pond power generation system.

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