阅读说明：本技术 生物质气化发电系统和发电方法 (Biomass gasification power generation system and power generation method ) 是由 广兼岳志 桐野智明 木村龙太郎 于 2019-02-01 设计创作，主要内容包括：一种生物质气化发电系统,其具备：由生物质和气化剂生成可燃气体的气体生成装置；由包含利用该气体生成装置而生成的可燃气体的燃料气来生成动力的内燃机；以及由利用该内燃机产生的动力来生成电力的发电机,前述发电系统还具备通过水电解而生成氧气和氢气的水电解装置,前述气化剂包含利用前述水电解装置而生成的氧气,前述燃料气包含利用前述水电解装置而生成的氢气,前述气化剂中的氧浓度为22体积％以上且40体积％以下。(A biomass gasification power generation system is provided with: a gas generating means for generating a combustible gas from the biomass and the gasifying agent; an internal combustion engine that generates power from a fuel gas containing a combustible gas generated by the gas generator; and a generator for generating electric power from power generated by the internal combustion engine, wherein the power generation system further includes a water electrolysis device for generating oxygen gas and hydrogen gas by electrolysis of water, the gasifying agent contains the oxygen gas generated by the water electrolysis device, the fuel gas contains the hydrogen gas generated by the water electrolysis device, and the oxygen concentration in the gasifying agent is 22 vol% or more and 40 vol% or less.)

1. A biomass gasification power generation system is provided with: a gas generating means for generating a combustible gas from the biomass and the gasifying agent; an internal combustion engine that generates power from a fuel gas containing a combustible gas generated by the gas generator; and a generator for generating electric power from power generated by the internal combustion engine,

the power generation system further includes a water electrolysis device that generates oxygen gas and hydrogen gas by electrolysis of water, the gasifying agent includes oxygen gas generated by the water electrolysis device, the fuel gas includes hydrogen gas generated by the water electrolysis device,

the oxygen concentration in the gasifying agent is 22 vol% or more and 40 vol% or less.

2. The biomass gasification power generation system according to claim 1, further comprising: an oxygen supply device for supplying the oxygen gas generated by the water electrolysis device to the gas generation device; and a hydrogen supply device that supplies the hydrogen gas generated by the water electrolysis device to the internal combustion engine.

3. The biomass gasification power generation system of claim 1 or 2, wherein the biomass is plant-derived biomass.

4. The biomass gasification power generation system according to any one of claims 1 to 3, wherein the biomass from plants comprises at least 1 of woody biomass, herbaceous biomass, plant residues, and food residues.

5. The biomass gasification power generation system according to any one of claims 1 to 4, wherein the water content in the biomass is 10 mass% or more.

6. The biomass gasification power generation system according to any one of claims 1 to 4, wherein the water content in the biomass is 10 mass% or more and 60 mass% or less.

7. The biomass gasification power generation system according to any one of claims 1 to 6, wherein a hydrogen concentration in the fuel gas is 15 vol% or more and 50 vol% or less.

8. A method of generating electricity, comprising the steps of: a gas generation step of generating a combustible gas from the biomass and the gasifying agent; a power generation step of generating power from a fuel gas containing the combustible gas generated in the gas generation step; and an electric power generation step of generating electric power from the motive power generated in the motive power generation step,

the power generation method further includes a water electrolysis step of generating oxygen gas and hydrogen gas by water electrolysis, wherein the gasifying agent contains the oxygen gas generated by the water electrolysis step, the fuel gas contains the hydrogen gas generated by the water electrolysis step, and the oxygen concentration in the gasifying agent is 22 vol% or more and 40 vol% or less.

9. The power generation method according to claim 8, wherein the gas generation step is performed by a gas generation device, the power generation step is performed by an internal combustion engine,

the power generation method further includes the steps of: an oxygen supply step of supplying the oxygen gas generated in the water electrolysis step to the gas generator; and a hydrogen supply step of supplying the hydrogen gas generated in the water electrolysis step to the internal combustion engine.

10. The power generation method according to claim 8 or 9, wherein the biomass is biomass from plants.

11. The power generation method according to any one of claims 8 to 10, wherein the biomass from plants comprises at least 1 of woody biomass, herbaceous biomass, plant residues, and food residues.

12. The biomass gasification power generation system according to any one of claims 8 to 11, wherein the water content in the biomass is 10 mass% or more.

13. The power generation method according to any one of claims 8 to 11, wherein the water content in the biomass is 10 mass% or more and 60 mass% or less.

14. The power generation method according to any one of claims 8 to 13, wherein a hydrogen concentration in the fuel gas is 15% by volume or more and 50% by volume or less.

15. The power generation method according to any one of claims 8 to 14, which uses the biomass gasification power generation system according to any one of claims 1 to 7.

Technical Field

The invention relates to a biomass gasification power generation system and a power generation method.

Background

A method of gasifying and utilizing biomass as a biogenic resource has been proposed. More specifically, when a gasifying agent containing air, oxygen, steam, or the like is charged into biomass in a gasification furnace and gasified, a synthesis gas containing hydrogen, carbon monoxide, and carbon dioxide as main components is generated. The resulting synthesis gas is used as a fuel for internal combustion engines. In this case, the gasification usually produces a synthesis gas and also produces by-products such as tar as hydrocarbons. The tar and the like produced cause clogging of the equipment and piping in the gasification furnace, and have a problem due to the generation of by-products.

Patent document 1 discloses a pyrolysis and gasification system including: a carbonization device for obtaining a carbide obtained by carbonizing a biomass or an organic waste at a predetermined temperature; and a pyrolysis/gasification device for obtaining a combustible gas by charging the carbide obtained by the carbonization device, steam, and air into a pyrolysis/gasification furnace. This document discloses: since the carbonization treatment is performed according to the properties of the organic waste, the generation of tar components can be suppressed, and a combustible gas having an optimum property such as high yield can be obtained. Further, this document discloses: in order to increase the concentration of the combustible gas produced, oxygen-enriched air produced by a Pressure Swing Adsorption (PSA) apparatus may be introduced instead of air.

Patent document 2 discloses a method for simultaneously producing hydrogen and electricity, which includes the steps of: a step of generating energy for producing hydrogen and oxygen using an intermittent renewable energy source; a step of transferring at least a portion of the energy to a production system to produce hydrogen and oxygen; introducing at least a portion of the hydrogen gas into a hydrogen transport system configured to transport the hydrogen gas from the hydrogen transport system to at least one of a power generation system or a hydrogen storage system; introducing at least a part of the oxygen gas into an oxygen transport system configured to transport the oxygen gas from the oxygen transport system to a biomass gasification system, and generating a synthesis gas by partial oxidation of the biomass raw material; and a step of introducing at least a portion of the synthesis gas to a power generation system, thereby producing power.

Disclosure of Invention

Problems to be solved by the invention

However, in the pyrolysis and gasification system described in patent document 1, from the viewpoint of suppressing the generation of tar components and the like, it is necessary to perform carbonization treatment at a high temperature of 300 ℃. In this document, power is generated from combustible gas generated by an internal combustion engine, and a generator is driven by the generated power.

In the method for simultaneously producing hydrogen and electric power described in patent document 2, no practical verification was made in the examples, and no study was made on the oxygen concentration in the oxygen gas used in the simultaneous production method.

Accordingly, an object of the present invention is to provide a power generation system and a power generation method that can improve the yield of combustible gas when generating combustible gas from biomass and can further improve the power for driving a generator.

Means for solving the problems

The present inventors have conducted intensive studies to solve the above problems, and as a result, have found that: in a power generation system for generating electric power from biomass, the above problems can be solved by a configuration in which oxygen gas generated by electrolysis of water is contained as a gasifying agent for generating a combustible gas from biomass, hydrogen gas generated by electrolysis of water is contained as a fuel gas for generating power together with the combustible gas, and the oxygen concentration in the gasifying agent is set within a predetermined range, and the present invention has been completed.

Specifically, this is achieved by the following means.

<1> a biomass gasification power generation system, comprising: a gas generation device (gas generation unit) that generates a combustible gas from the biomass and the gasifying agent; an internal combustion engine that generates power from a fuel gas containing a combustible gas generated by the gas generator; and a generator for generating electric power from power generated by the internal combustion engine, wherein the power generation system further includes a water electrolysis device for generating oxygen gas and hydrogen gas by electrolysis of water, the gasifying agent contains the oxygen gas generated by the water electrolysis device, the fuel gas contains the hydrogen gas generated by the water electrolysis device, and the oxygen concentration in the gasifying agent is 22 vol% or more and 40 vol% or less.

<2> the biomass gasification power generation system according to <1>, further comprising: an oxygen supply device (oxygen supply unit) for supplying the oxygen gas generated by the water electrolysis device to the gas generation device; and a hydrogen supply device for supplying the hydrogen gas generated by the water electrolysis device to the internal combustion engine.

<3> the biomass gasification power generation system according to <1> or <2>, wherein the biomass is biomass derived from a plant.

<4> the biomass gasification power generation system according to any one of <1> to <3>, wherein the plant-derived biomass contains at least 1 of woody biomass, herbaceous biomass, plant residues, and food residues.

<5> the biomass gasification power generation system according to any one of <1> to <4>, wherein the water content in the biomass is 10 mass% or more.

<6> the biomass gasification power generation system according to any one of <1> to <4>, wherein the water content in the biomass is 10 mass% or more and 60 mass% or less.

<7> the biomass gasification power generation system according to any one of <1> to <6>, wherein a hydrogen concentration in the fuel gas is 15% by volume or more and 50% by volume or less.

<8> a power generation method comprising the steps of: a gas generation step of generating a combustible gas from the biomass and the gasifying agent; a power generation step of generating power from a fuel gas containing the combustible gas generated in the gas generation step; and an electric power generation step of generating electric power from the motive power generated in the motive power generation step, wherein the power generation method further comprises a water electrolysis step of generating oxygen gas and hydrogen gas by electrolysis of water, the gasifying agent contains the oxygen gas generated in the water electrolysis step, the fuel gas contains the hydrogen gas generated in the water electrolysis step, and the oxygen concentration in the gasifying agent is 22 vol% or more and 40 vol% or less.

<9> the power generation method according to <8>, wherein the gas generation step is performed by a gas generation device, and the power generation step is performed by an internal combustion engine, the power generation method further comprising: an oxygen supply step of supplying the oxygen gas generated in the water electrolysis step to the gas generator; and a hydrogen supply step of supplying the hydrogen gas generated in the water electrolysis step to the internal combustion engine.

<10> the power generation method according to <8> or <9>, wherein the biomass is biomass derived from a plant.

<11> the power generation method according to any one of <8> to <10>, wherein the plant-derived biomass contains at least 1 of woody biomass, herbaceous biomass, plant residues, and food residues.

<12> the biomass gasification power generation system according to any one of <8> to <11>, wherein the water content in the biomass is 10 mass% or more.

<13> the power generation method according to any one of <8> to <11>, wherein a water content in the biomass is 10 mass% or more and 60 mass% or less.

<14> the power generation method according to any one of <8> to <13>, wherein a hydrogen concentration in the fuel gas is 15% by volume or more and 50% by volume or less.

<15> the power generation method according to any one of <8> to <14>, which uses the biomass gasification power generation system according to any one of <1> to <7 >.

The biomass gasification power generation system of the present invention is a power generation system including: a gas generation device (gas generation unit) that generates a combustible gas from the biomass and the gasifying agent; an internal combustion engine that generates power from a fuel gas containing a combustible gas generated by the gas generation device; and a generator that generates electric power from power generated by the internal combustion engine. The power generation system further includes a water electrolysis device that generates oxygen gas and hydrogen gas by electrolysis of water, the gasifying agent includes oxygen gas generated by the water electrolysis device, and the fuel gas includes hydrogen gas generated by the water electrolysis device. The oxygen concentration in the gasifying agent is 22 vol% or more and 40 vol% or less.

In the pyrolysis and gasification system described in patent document 1, in order to obtain biomass with properties optimal for gasification, carbonization treatment at a high temperature of 300 ℃ or higher is required, and a carbonization apparatus is necessary for this purpose. Therefore, the pyrolysis and gasification system described in patent document 1 has the following problems: in addition to the increase in size or complexity of the entire system, energy consumption is consumed for carbonization of biomass, and energy efficiency is insufficient. In contrast, the biomass gasification power generation system of the present invention is configured as follows: which contains oxygen generated by the water electrolysis device as a gasifying agent for generating combustible gas from biomass. Thus, the biomass gasification power generation system of the present invention can stably gasify biomass without requiring a carbonizing device, and as a result, the entire system can be reduced in size or simplified. In addition, the biomass gasification power generation system of the present invention can reduce the nitrogen concentration in the gasifying agent and increase the yield of the combustible gas by increasing the oxygen concentration in the gasifying agent by electrolysis of water. In the pyrolysis and gasification system described in patent document 1, power is generated from the generated combustible gas, and the generated power is used to drive a generator. In contrast, the biomass gasification power generation system according to the present invention is configured to include hydrogen gas generated by water electrolysis as fuel gas for generating power, and thereby can increase power for driving a generator. Further, the biomass gasification power generation system of the present invention includes oxygen gas generated by the water electrolysis device as the gasifying agent, so that combustible gas can be efficiently generated from biomass, and thus generation of by-products such as tar can be suppressed.

Further, patent document 1 discloses: oxygen-enriched air generated by a Pressure Swing Adsorption (PSA) apparatus may be introduced to increase the concentration of the generated combustible gas. A pressure swing adsorption apparatus is an apparatus for selectively recovering a predetermined gas such as oxygen or hydrogen by repeating adsorption with an adsorbent under high pressure conditions and desorption under low pressure conditions. Therefore, it is also conceivable to use a pressure swing adsorption apparatus for increasing the concentration of the combustible gas as in patent document 1. However, in a system using a pressure swing adsorption apparatus, in order to selectively recover the gas, it is necessary to provide a plurality of adsorption tanks or a buffer tank for storing the gas taken out by the adsorption tanks, and therefore, there is a problem that it is difficult to cope with downsizing. Further, the system using the pressure swing adsorption apparatus (PSA) requires two types of pressure swing adsorption apparatuses for oxygen, which selectively recovers oxygen, and for hydrogen, which selectively recovers hydrogen, and also causes the following problems: not only further downsizing cannot be coped with, but also the cost, production efficiency, and the like of the entire system are insufficient. In contrast, in the present invention, a water electrolysis device is used to increase the concentration of the combustible gas to be generated, and the size of the water electrolysis cell is appropriately adjusted to cope with the reduction in size of the water electrolysis device, so that the biomass gasification power generation system as a whole can be reduced in size. In addition, in the present invention, since the oxygen gas and the hydrogen gas can be generated by the water electrolysis device, and it is not necessary to prepare generation devices for the oxygen generation use and the hydrogen generation use, respectively, the present invention has an advantage of excellent cost and production efficiency.

In the biomass gasification power generation system of the present invention, the oxygen concentration in the gasifying agent is 22 vol% or more and 40 vol% or less. In the reaction between the biomass gas and the gasifying agent, generally, hydrocarbons in the biomass gas are oxidized by oxygen in the gasifying agent to generate carbon monoxide as a combustible gas. Therefore, in the biomass gasification power generation system of the present invention, when the oxygen concentration in the gasifying agent is 22 vol% or more, the oxidation reaction is easily performed, and the yield of the combustible gas can be further improved. On the other hand, when the oxygen concentration in the gasifying agent is 40 vol% or more, the hydrocarbons in the biomass gas are further oxidized, carbon dioxide which is a nonflammable gas is easily generated, and the yield of the flammable gas is easily lowered. Further, if the oxygen concentration in the gasifying agent is 40 vol% or less, partial combustion in the gas generator is less likely to occur, and stable gasification can be achieved. Therefore, the biomass gasification power generation system of the present invention can increase the yield of the combustible gas by setting the oxygen concentration in the gasifying agent within the above range, and can further increase the power for driving the generator.

The biomass gasification power generation system of the present invention preferably further includes: an oxygen supply device (oxygen supply unit) that supplies oxygen gas generated by the water electrolysis device to the gas generation device, and a hydrogen supply device (hydrogen supply unit) that supplies hydrogen gas generated by the water electrolysis device to the internal combustion engine. The biomass gasification power generation system of the present invention is provided with the oxygen supply device and the hydrogen supply device, respectively, and thus can stably supply the hydrogen gas and the oxygen gas generated by the water electrolysis device to the gas generation device and the internal combustion engine without leakage, and therefore, the yield of the combustible gas can be further improved, and the power for driving the generator can be further improved.

The separate provision of the oxygen supply device and the hydrogen supply device means that a portion for supplying oxygen and a portion for supplying hydrogen are independent of each other, and it is needless to say that the two devices are independently disposed in the same device.

The water electrolysis device preferably performs water electrolysis using power generated by a variable power source such as solar power generation or wind power generation. The biomass gasification power generation system according to the present invention can suppress the amount of power consumption from the outside required for driving the water electrolysis device by performing water electrolysis using the electric power generated by the water electrolysis device using the variable power supply, and therefore, can further improve the energy efficiency of the entire biomass gasification power generation system. Further, since the power generated by the biomass gasification power generation system of the present invention is controllable, the control power can be generated using the variable power generated by the variable power source.

The biomass is preferably biomass from a plant. In the biomass gasification power generation system of the present invention, when biomass derived from plants is used as biomass, the yield of combustible gas can be further improved.

The water content in the biomass is preferably 10 mass% or more, and preferably 60 mass% or less. If biomass having a large water content is used, for example, the temperature of a reaction system for reacting the biomass with a gasifying agent needs to be further increased due to the large water content, and there is a risk that the temperature is locally lowered in the reaction system. In contrast, in the biomass gasification power generation system of the present invention, when the water content in the biomass is 60 mass% or less, the temperature of the reaction system does not need to be excessively increased, and further, the temperature is not easily locally lowered and the reaction is easily and smoothly performed, so that the energy efficiency of the entire system can be further improved and the yield of the combustible gas can be further improved. From the viewpoint of facilitating and smoothly performing the reaction, the water content in the biomass is preferably small, but a complicated treatment step is required for the moisture removal treatment for reducing the water content in the biomass as much as possible. In contrast, in the biomass gasification power generation system of the present invention, even if the water content in the biomass is 10 mass% or more, the reaction can be sufficiently and smoothly performed, the energy efficiency of the entire system can be further improved, and the yield of the combustible gas can be further improved. Therefore, a water content of 10 mass% or more in the biomass is advantageous in that a complicated treatment step is not required and the production cost can be reduced.

In the present specification, the water content in the biomass is calculated from a moisture content reference represented by the following formula.

Water content (% by mass) X/Y × 100

X: quality of water in biomass

Y: mass of biomass

The water content is a value immediately before charging into the gas generator, and is measured at 25 ℃.

The hydrogen concentration in the fuel gas is preferably 15% by volume or more, and preferably 50% by volume or less. In the biomass gasification power generation system of the present invention, when the hydrogen concentration in the fuel gas is 15 vol% or more, the power for driving the generator can be further increased. On the other hand, if the hydrogen concentration in the fuel gas is 50% by volume or less, stable combustion in the internal combustion engine is possible.

The power generation method of the present invention includes the steps of: a gas generation step of generating a combustible gas from the biomass and the gasifying agent; a power generation step of generating power from a fuel gas containing the combustible gas generated in the gas generation step; and an electric power generation step of generating electric power from the power generated by the power generation step. The power generation method further includes a water electrolysis step of generating oxygen gas and hydrogen gas by water electrolysis, wherein the gasifying agent contains the oxygen gas generated by the water electrolysis step, the fuel gas contains the hydrogen gas generated by the water electrolysis step, and the oxygen concentration in the gasifying agent is 22 vol% or more and 40 vol% or less.

In the present specification, the term "step" includes not only an independent step but also a step that is not clearly distinguished from other steps, and is included in the term as long as the desired action of the step is achieved.

The power generation method of the present invention is the same as the preferable range of the biomass gasification power generation system, unless otherwise specified.

The power generation method of the present invention is configured to include oxygen generated by the water electrolysis step as a gasifying agent for generating a combustible gas from biomass, and thereby biomass and the like can be stably gasified. In addition, the biomass gasification power generation system of the present invention can reduce the nitrogen concentration in the gasifying agent and increase the yield of the combustible gas by increasing the oxygen concentration in the gasifying agent by electrolysis of water. This can suppress the energy consumption amount as compared with a method of carbonizing biomass or the like at a high temperature, and therefore can improve the energy efficiency of the entire system. Further, the biomass gasification power generation system of the present invention can increase the power for driving the generator by a configuration including the hydrogen gas generated by the water electrolysis step as the fuel gas for generating the power.

In the power generation method of the present invention, the oxygen concentration in the gasifying agent is 22 vol% or more and 40 vol% or less. In the power generation method of the present invention, if the oxygen concentration in the gasifying agent is 22 vol% or more, the oxidation reaction is easily performed, and the yield of the combustible gas can be further improved. On the other hand, in the power generation method of the present invention, if the oxygen concentration in the gasifying agent is 40 vol% or less, partial combustion in the gas generator is less likely to occur, and stable gasification can be achieved. Therefore, in the power generation method of the present invention, the oxygen concentration in the gasifying agent is set to be within the above range, whereby the yield of the combustible gas can be increased, and the power for driving the power generator can be further increased.

It is preferable that: the gas generation step is performed by a gas generation device, and the power generation step is performed by an internal combustion engine. Further, the power generation method preferably further includes: an oxygen supply step of supplying the oxygen gas generated in the water electrolysis step to the gas generator; and a hydrogen supply step of supplying the hydrogen gas generated in the water electrolysis step to the internal combustion engine. The power generation method of the present invention includes the oxygen supply step and the hydrogen supply step, respectively, and thus can stably supply the hydrogen gas and the oxygen gas generated in the water electrolysis step to the gas generator and the internal combustion engine without leakage of each of them, and therefore can further improve the yield of the combustible gas and the power for driving the generator.

The water electrolysis step is preferably performed by using power generated by a variable power source such as solar power generation or wind power generation. In the power generation method of the present invention, the water electrolysis step can suppress the power from the outside necessary for the water electrolysis when the water electrolysis is performed using the power generated by the variable power supply, and therefore, the energy efficiency of the entire power generation method can be further improved. Further, since the power generated by the biomass gasification power generation system is controllable, the control power can be generated using the variable power generated by the variable power supply.

The biomass is preferably biomass from a plant. In the power generation method of the present invention, when biomass derived from plants is used as the biomass, the yield of the combustible gas can be further improved.

The water content in the biomass is preferably 10 mass% or more, and preferably 60 mass% or less. In the power generation method of the present invention, when the water content in the biomass is 60 mass% or less, the temperature of the reaction system does not need to be excessively increased, and further, the temperature is not easily locally lowered and the reaction is easily and smoothly performed, so that the energy efficiency of the entire power generation method can be further improved and the yield of the combustible gas can be further improved. From the viewpoint of facilitating and smoothly performing the reaction, the water content in the biomass is preferably small, but a complicated treatment step is required for the moisture removal treatment for reducing the water content in the biomass as much as possible. In contrast, in the biomass gasification power generation system of the present invention, even if the water content in the biomass is 10 mass% or more, the reaction can be sufficiently and smoothly performed, the energy efficiency of the entire system can be further improved, and the yield of the combustible gas can be further improved. Therefore, a water content of 10 mass% or more in the biomass is advantageous in that a complicated treatment step is not required and the production cost can be reduced.

The hydrogen concentration in the fuel gas is preferably 15% by volume or more, and preferably 50% by volume or less. In the power generation method of the present invention, when the hydrogen concentration in the fuel gas is 15 vol% or more, the power used in the power generation step can be further increased. On the other hand, in the power generation method of the present invention, if the hydrogen concentration in the fuel gas is 50 vol% or less, stable combustion in the internal combustion engine is possible.

The power generation method preferably uses the power generation system of the present invention.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide a power generation system and a power generation method that can improve the yield of combustible gas and further improve the power for driving a generator when combustible gas is generated from biomass.

Drawings

Fig. 1 is a schematic diagram showing an example of the configuration of a biomass gasification power generation system according to the present invention.

Detailed Description

The present embodiment (hereinafter, simply referred to as "the present embodiment") will be described below. The following embodiments are merely examples for illustrating the present invention, and the present invention is not limited to the embodiments.

[ Biomass gasification electric Power Generation System 1]

Fig. 1 is a schematic diagram showing an example of the configuration of the biomass gasification power generation system according to the present embodiment. The biomass gasification power generation system 1 shown in fig. 1 includes a gas generator 2, an internal combustion engine 3, a power generator 4, a water electrolysis device 5, an oxygen supply device 6, and a hydrogen supply device 7. The gas generating apparatus 2 generates a combustible gas from the biomass and the gasifying agent. The internal combustion engine 3 generates power from fuel gas containing the combustible gas generated by the gas generator 2. The generator 4 generates electric power from the power generated by the internal combustion engine 3. The water electrolysis device 5 generates oxygen and hydrogen by electrolysis of water. The oxygen supply device 6 supplies the oxygen gas generated by the water electrolysis device 5 to the gas generator 2. The hydrogen supply device 7 supplies the hydrogen gas generated by the water electrolysis device 5 to the internal combustion engine 3. In the present embodiment, the oxygen supply device 6 and the hydrogen supply device 7 are arbitrary components.

(gas generator 2)

The gas generator 2 is not particularly limited as long as it can generate a combustible gas from the biomass and the gasifying agent. A specific example of the gas generator 2 is preferably a gasification furnace. Examples of the form of the gasification furnace include a fixed bed form, a fluidized bed form, a spouted bed form, a rotary furnace form, and the like, and the form of the gasification furnace is preferably a fixed bed form from the viewpoint of the equipment cost and the size reduction. Fixed bed forms are generally classified as: the fixed bed type is preferably a downward flow type in which the biomass and the gasifying agent flow in the same direction and an upward flow type in which the biomass and the gasifying agent flow in opposite directions, from the viewpoint of preventing the generation of by-products such as tar in the combustible gas.

The downward gas flow type gasification furnace includes, for example, a pyrolysis layer formed at the uppermost portion in the furnace, a combustion layer formed below the pyrolysis layer, and a reduction layer formed below the combustion layer. In the pyrolysis layer, biomass is pyrolyzed into methane, carbon monoxide, carbon dioxide, hydrogen, water, carbon, tar, ash and the like at the temperature of 200-600 ℃. In the combustion layer, carbon, tar, hydrogen, carbon monoxide and the like are oxidized into carbon monoxide, carbon dioxide, water and the like at a temperature of 600 to 1300 ℃. In the reduction layer, at the temperature of 600-800 ℃, carbon reacts with carbon dioxide and water or methane reacts with water, so that combustible gases such as carbon monoxide and hydrogen are generated.

(internal combustion engine 3)

The internal combustion engine 3 is not particularly limited as long as it can generate power from fuel gas containing the combustible gas generated by the gas generator 2. Specific examples of the internal combustion engine 3 include a gas engine, a gasoline engine, a diesel engine, and a gas turbine. The internal combustion engine 3 includes, for example, a rotating portion connected to the generator 4 and a drive shaft for rotating the rotating portion. The internal combustion engine 3 converts energy generated by combustion of the fuel gas into rotational energy of the drive shaft, and the rotating portion rotates, whereby the generator 4 generates electricity. The internal combustion engine 3 is provided with, for example, an exhaust line, and the internal combustion engine 3 discharges exhaust gas generated by burning fuel gas from the exhaust line.

(Generator 4)

The generator 4 is not particularly limited as long as it can generate electric power from the motive power generated by the internal combustion engine 3. The generator 4 is connected to, for example, a rotating portion of the internal combustion engine 3, and generates power by rotating the rotating portion by rotational energy generated in the internal combustion engine 3.

(Water electrolysis apparatus 5)

The water electrolysis device 5 is not particularly limited as long as it can generate oxygen gas and hydrogen gas by electrolysis of water. Examples of the water electrolysis device 5 include an alkaline water electrolysis device for performing water electrolysis using an alkaline aqueous solution as an electrolyte, and a solid polymer water electrolysis device for performing water electrolysis using an ion exchange membrane as an electrolyte. Among these, from the viewpoint of production efficiency, a solid polymer water electrolysis device is preferable. The solid polymer water electrolysis device may include, for example: the water electrolysis device comprises a water electrolysis tank, a water supply device (water supply unit), a power supply device (power supply unit), a first gas-liquid separation device (first gas-liquid separation unit) and a second gas-liquid separation device (second gas-liquid separation unit). The water electrolyzer may include, for example: the electrolytic cell comprises a water electrolytic membrane having a solid polymer electrolyte membrane and metal electrodes formed on both surfaces of the solid polymer electrolyte membrane, and an anode chamber and a cathode chamber partitioned by the water electrolytic membrane. The water supply device supplies water to the water electrolyzer, for example. The power supply device supplies power to, for example, a metal electrode of a water electrolysis membrane in a water electrolysis cell. The first gas-liquid separating device separates a mixture of oxygen and water, which is generated by electrolysis of water, for example, in an anode chamber of a water electrolysis cell, into oxygen gas and water. The second gas-liquid separation device separates a mixture of hydrogen gas and water, which is generated by electrolysis of water in, for example, a cathode chamber of a water electrolysis cell, into hydrogen gas and pure water. In the case of the solid polymer water electrolysis apparatus having the above-described configuration, oxygen generated in the anode chamber of the water electrolysis cell flows into the first gas-liquid separator together with water, and the oxygen is separated from the water in the separation chamber of the first gas-liquid separator and is retained in the upper portion of the separation chamber. On the other hand, the hydrogen gas generated in the cathode chamber of the water electrolyzer flows into the second gas-liquid separator together with water, and in the separation chamber of the second gas-liquid separator, the hydrogen gas is separated from the water and is retained in the upper part of the separation chamber. Here, the water separated from the oxygen gas or the hydrogen gas by each gas-liquid separator is retained on the bottom side of each separation chamber and is discharged through the discharge valve. The above-mentioned solid polymer water electrolysis apparatus operates in this manner, and can extract oxygen gas and hydrogen gas from water with high purity.

(oxygen supply apparatus 6)

The oxygen supply device 6 is not particularly limited as long as it can supply the oxygen gas generated by the water electrolysis device 5 to the gas generator 2. The oxygen supply device 6 may include, for example, a supply pipe that connects the water electrolysis device 5 and the gas generator 2 and supplies oxygen generated by the water electrolysis device 5. The oxygen supply device 6 may be provided with a tank for storing oxygen between the supply pipe and the water electrolysis device. The oxygen supply apparatus 6 may include, as necessary: an on-off valve provided in the middle of the supply pipe and used for starting or stopping oxygen supply; a flow meter provided in the middle of the supply pipe and measuring the flow rate of oxygen; and a control device for controlling the flow rate of oxygen based on the measurement value of the flow meter.

(Hydrogen supplying means 7)

The hydrogen supply device 7 is not particularly limited as long as it can supply the oxygen gas generated by the water electrolysis device 5 to the internal combustion engine 3. The hydrogen supply device 7 may include, for example, a supply pipe that connects the water electrolysis device 5 and the internal combustion engine 3 and supplies hydrogen gas generated by the water electrolysis device 5. The hydrogen supply device 7 may include a tank for storing hydrogen gas between the supply pipe and the water electrolysis device. The hydrogen supply device 7 may include, as necessary: an on-off valve provided in the middle of the supply pipe and configured to start or stop hydrogen supply; a flow meter provided in the middle of the supply pipe for measuring the flow rate of hydrogen gas; and a control device for controlling the hydrogen flow rate based on the measurement value of the flow meter.

[ method of generating electric Power ]

The power generation method of the present embodiment is performed using, for example, a biomass gasification power generation system (biomass gasification power generation apparatus) 1 shown in fig. 1. However, the power generation method of the present embodiment is not limited to the use of the biomass gasification power generation system (biomass gasification power generation apparatus) 1 shown in fig. 1. The power generation method of the present embodiment includes a gas generation step, a power generation step, an electric power generation step, a water electrolysis step, an oxygen supply step, and a hydrogen supply step. The gas generation step generates a combustible gas from the biomass and the gasifying agent by, for example, the gas generator 2. The power generation step generates power from a fuel gas containing the combustible gas generated in the gas generation step, for example, by the internal combustion engine 3. The electric power generation step generates electric power from the motive power generated in the motive power generation step by the generator 4, for example. The water electrolysis step generates oxygen gas and hydrogen gas by water electrolysis using, for example, the water electrolysis device 5. In the oxygen supply step, the oxygen gas generated in the water electrolysis step is supplied to the gas generator 2 by, for example, the oxygen supply unit 6. The hydrogen supply step supplies the hydrogen gas generated in the water electrolysis step to the internal combustion engine 3 by, for example, the hydrogen supply device 7. In the present embodiment, the oxygen supply step and the hydrogen supply step are optional components.

In the power generation method of the present embodiment, first, oxygen gas and hydrogen gas are generated by the water electrolysis device 5 in the water electrolysis step. Next, in the oxygen supply step, the generated oxygen gas is supplied to the gas generator 2 through the oxygen supply device 6, whereby the generated oxygen gas is included in the gasifying agent for generating the combustible gas from the biomass. Next, in the gas generation step, a combustible gas is generated from the biomass and the gasifying agent by the gas generator 2. Next, in the hydrogen supply step, the generated hydrogen gas is supplied to the internal combustion engine 3 through the hydrogen supply device 7, so that the fuel gas contains both the generated hydrogen gas and the combustible gas generated in the gas generation step. Next, in the power generation step, power is generated from the fuel gas by the internal combustion engine 3. Next, in the electric power generation step, the power generated in the power generation step is generated as electric power by the generator 4.

The power generation system and the power generation method according to the present embodiment are configured to include oxygen generated by the water electrolysis device 5 (water electrolysis step) in the gasifying agent, thereby making it possible to improve the yield of the combustible gas generated by the gas generation device 2 (gas generation step). Further, the power generation system and the power generation method according to the present embodiment can improve the energy efficiency of the entire system because the biomass and the like are made to have properties optimal for gasification by increasing the oxygen concentration in the gasifying agent by water electrolysis, and the energy consumption amount can be suppressed as compared with a method of carbonizing the biomass and the like at a high temperature. Further, the power generation system and the power generation method of the present embodiment can increase the power for driving the power generator 4 by including the hydrogen gas generated by the water electrolysis device 5 (water electrolysis step) in the fuel gas.

(Biomass)

As the biomass used in the biomass gasification power generation system of the present embodiment, a substance other than fossil resources, which is a renewable organic resource derived from a living organism, may be used widely, and may be plant-derived biomass or animal-derived biomass, and from the viewpoint of further improving the yield of combustible gas, plant-derived biomass is preferable. Examples of the plant-derived biomass include woody biomass such as cedar wood chips, cedar bark, and white pellets (white pellets); herbaceous biomass such as bamboo, rice hull, bagasse, beet pulp, wheat straw, corn stalk, rice straw, cassava residue and the like; plant residues such as pericarp; and food residues such as coffee baking residue, tea residue, wheat bran, etc.

Further, biomass may be classified into waste biomass, unused biomass, resource crops, and the like. Waste biomass includes waste paper, livestock excrement, food waste, construction lumber, lumber mill residue, sewage sludge, and the like, unutilized biomass includes straw, wheat straw, rice husk, and the like, and resource crops include plants cultivated for energy or product production purposes, such as sugarcane, corn, and the like.

These biomasses may be used alone in 1 kind, or in combination in 2 or more kinds.

The water content in the biomass is preferably 10 mass% or more, and preferably 60 mass% or less. In the biomass gasification power generation system and the power generation method according to the present embodiment, when the water content in the biomass is 60 mass% or less, the temperature of the reaction system does not need to be excessively increased, and further, the temperature is not easily locally lowered, and the reaction is easily and smoothly performed, so that the energy efficiency of the whole system or the whole process can be further improved, and the yield of the combustible gas can be further improved. From the same viewpoint, the water content in the biomass is more preferably 13 mass% or more, and still more preferably 15 mass% or more. Further, the water content in the biomass is more preferably 50% by mass or less, and still more preferably 40% by mass or less.

(gasifying agent)

The gasifying agent of the present embodiment contains oxygen generated by the water electrolysis device, and may contain oxygen-containing gas from the outside as necessary. Examples of the oxygen-containing gas include air, oxygen-enriched air, pure oxygen, and the like. The gasifying agent is an agent for gasifying biomass, and examples thereof include oxygen, air, or a mixture thereof, or a substance obtained by adding steam to oxygen, air, or a mixture thereof. In particular, the total of oxygen, air and steam in the gasifying agent preferably occupies 99% by volume or more of the gasifying agent.

In the oxygen supply step, as a method of supplying the oxygen gas generated by the electrolysis of water to the gas generator, for example, the oxygen gas generated by the electrolysis of water and an oxygen-containing gas from the outside may be supplied simultaneously to the gas generator, or the oxygen-containing gas from the outside may be supplied to the gas generator, adjusted so that the oxygen concentration reaches a predetermined concentration, and then the oxygen gas generated by the electrolysis of water may be supplied to the gas generator.

The oxygen concentration in the gasifying agent is 22 vol% or more and 40 vol% or less. In the biomass gasification power generation system and the power generation method according to the present embodiment, when the oxygen concentration in the gasifying agent is 22 vol% or more, the generation of by-products such as tar is difficult, the oxidation reaction is easily performed, and the yield of combustible gas can be further improved. On the other hand, if the oxygen concentration in the gasifying agent is 40 vol% or less, partial combustion in the gas generator is less likely to occur, and stable gasification can be achieved. From the same viewpoint, the oxygen concentration in the gasifying agent is preferably 24 vol% or more, and more preferably 26 vol% or more. The oxygen concentration in the gasifying agent is preferably 35 vol% or less, and more preferably 30 vol% or less.

The nitrogen concentration of the gasifying agent is preferably 76 vol% or less, and more preferably 74 vol% or less. With this configuration, the yield of the combustible gas can be improved. The lower limit is preferably 65 vol% or more, and more preferably 70 vol% or more. By making such a configuration, stable vaporization can be achieved.

(Fuel gas)

The fuel gas of the present embodiment includes a combustible gas generated by the gas generator and a hydrogen gas generated by the water electrolysis device. The fuel gas may be supplied with fuel gas from the outside as needed. In the present specification, the combustible gas means a gas having combustibility in the presence of oxygen, and carbon monoxide and hydrogen are exemplified.

The hydrogen concentration in the fuel gas is preferably 15% by volume or more, and preferably 50% by volume or less. In the biomass gasification power generation system and the power generation method of the present invention, if the hydrogen concentration in the fuel gas is 15 vol% or more, the power for driving the generator can be further increased. On the other hand, if the hydrogen concentration in the fuel gas is 50% by volume or less, stable combustion in the internal combustion engine is possible. From the same viewpoint, the hydrogen concentration in the fuel gas is more preferably 17 vol% or more, and still more preferably 19 vol% or more. The hydrogen concentration in the fuel gas is more preferably 40 vol% or less, and still more preferably 30 vol% or less.

In the present invention, the content of combustible gas (total amount of carbon monoxide and hydrogen) in the fuel gas may be 32 vol% or more, and may be 33 vol% or more. The upper limit is, for example, 50 vol% or less, and further 40 vol% or less.

(modification example)

In the biomass gasification power generation system of the present embodiment, the water electrolysis device preferably performs water electrolysis using electric power generated by a variable power source such as solar power generation or wind power generation. In this case, the power generation method of the present embodiment is preferably configured to perform water electrolysis by using power generated by a variable power source such as solar power generation or wind power generation in the water electrolysis step. In the biomass gasification power generation system and the power generation method according to the present embodiment, the water electrolysis device (water electrolysis step) performs water electrolysis using electric power generated by a variable power source such as solar power generation or wind power generation, and thus the amount of external electric power consumption required for water electrolysis can be suppressed, and therefore, the energy efficiency of the entire biomass gasification power generation system or the entire steps can be further improved.