Biomass gas and hydrogen production method

Abstract

To provide a biomass gas production method, a hydrogen production method, a biomass gas production system, and a hydrogen production system, that can reduce by-products such as tar in pyrolysis gasification of biomass, and improve gasification efficiency of the biomass and an amount of a biomass gas generated.SOLUTION: A biomass gas production method comprises a pyrolysis gasification step of obtaining biomass gas by gasification using steam containing a metal composition, with biomass as a raw material.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing biomass gas and hydrogen. [Background technology]

[0002] Until now, woody biomass has been used as combustion fuel or treated as waste. Meanwhile, various types of pyrolysis gasifiers have been developed, such as a single-stage gasification technology in which biomass is directly pyrolyzed and gasified using high-temperature steam, and a two-stage gasification technology in which the charcoal produced by the carbonization process of biomass is pyrolyzed and gasified using high-temperature steam. Biomass gas (a mixed gas containing CO, hydrogen, CO2, methane, etc.) produced by pyrolysis gasification is used to generate electricity in gas engines, and high-purity hydrogen is produced by a reforming reaction of the biomass gas and used for fuel cells, etc. (see Non-Patent Documents 1 to 4).

[0003] There are various types of pyrolysis gasification of biomass, depending on the biomass supply method, reaction conditions such as pressure, temperature, and flow rate of oxidizing agent such as steam, content, heating method, gasification furnace structure, etc. Regarding pressure, there are two types of pyrolysis gasification of biomass: normal pressure (0.1 to 0.12 MPa) and pressurized pressure (0.2 to 2 MPa). Regarding temperature, there are two types of pyrolysis gasification of biomass: low temperature (less than 650°C) and high temperature (650 to 1200°C). As a gasification agent, there is a method of pyrolysis gasifying biomass using air, oxygen, or steam. Heating methods include internal combustion gasification, in which part of the biomass used as gasification feedstock is reacted with oxygen and combusted internally, and external combustion gasification, in which the biomass used as feedstock and steam are heated externally. Gasification furnace types include fixed bed, fluidized bed, moving bed, stirred bed, and rotary kiln types. Biomass pyrolysis gasification is classified according to these types and combinations.

[0004] Methods for utilizing biomass gas produced by pyrolysis and gasification of biomass include gas engine power generation and hydrogen production using a steam reforming reaction. Examples of developments to date include a single-stage pyrolysis gasification method in which biomass is gasified directly using high-temperature steam, and a two-stage pyrolysis gasification method in which biomass is carbonized in a carbonization furnace and the resulting char is gasified using high-temperature steam (see Patent Documents 1 and 2, and Non-Patent Documents 1 to 5). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2008-88434 [Patent Document 2] Japanese Patent No. 5342264 [Non-patent literature]

[0006] [Non-Patent Document 1] "New Developments in Biomass Refinery Catalyst Technology," edited by Masaru Ichikawa, CMC Publishing (2011), pp. 70-77, pp. 99-106 [Non-patent document 2] D. Xianwen et al., Energy Fuels 14, 2000, 552 [Non-patent document 3] ID Barn et al., Energy Fuels 14, 2000, 889 [Non-patent document 4] Kenichi Sasauchi, Power Generation by Pyrolysis Gasification of Biomass, Journal of the Combustion Society of Japan, Vol. 47, No. 139 (2005) pp. 31-39 [Non-Patent Document 5] Masaru Ichikawa, Life and Environment, Vol. 61, No. 1 (2016) "New developments in hydrogen energy technology utilizing biomass resources" Summary of the Invention [Problem to be solved by the invention]

[0007] However, with conventional technology, the gasification efficiency in biomass pyrolysis gasification (biomass gas calorific value / (biomass calorific value + external heat input calorific value) × 100) is at most 50 to 65%, and there is a demand for improvements in gasification efficiency and an increase in the amount of gas produced. In addition, conventional technologies produce by-products such as tar, wood vinegar, and coke during pyrolysis gasification. There is a need to reduce the cost of processing these by-products and the burden on the local environment. There is also a need to improve the utilization of waste heat from high-temperature pyrolysis gasifiers. In addition, in hydrogen production methods using biomass gas, there is a need to reduce energy consumption and hydrogen production costs by lowering the temperature and pressure of the reaction process and improving catalyst performance.

[0008] The present invention aims to provide a biomass gas production method, a hydrogen production method, a biomass gas production system, and a hydrogen production system that can reduce by-products such as tar during the pyrolysis gasification of biomass and improve the biomass gasification efficiency and the amount of biomass gas produced. [Means for solving the problem]

[0009] The present invention has the following aspects. [1] A method for producing biomass gas, comprising a pyrolysis gasification process in which biomass is used as a raw material and is gasified with steam containing metal components to obtain biomass gas. [2] The biomass gas production method described in [1], wherein the pyrolysis gasification process includes a combustion operation for burning a portion of the biomass and a gasification operation for obtaining the biomass gas from another portion of the biomass and the steam, and the gasification operation uses the exhaust heat generated in the combustion operation as a heat source. [3] The biomass gas production method described in [1], wherein the pyrolysis gasification process includes a carbonization operation for carbonizing the biomass to obtain a carbonized material, and a carbonized material gasification operation for obtaining the biomass gas from the carbonized material and the steam. [4] The biomass gas production method according to any one of [1] to [3], further comprising a steam heating step of heating the steam using exhaust heat generated in the pyrolysis gasification step as a heat source. [5] The method for producing a biomass gas according to any one of [1] to [4], wherein the metal component contains at least one element selected from the group consisting of sodium, potassium, lithium, calcium, magnesium, strontium, barium, boron, aluminum, and gallium. [6] The method for producing biomass gas according to any one of [1] to [5], wherein the metal component contains at least one salt selected from the group consisting of carbonates, sulfates, hydrochlorides, and silicates, and the content of the salt is 10 to 10,000 mg per 1 kg of the steam.

[0010] [7] A hydrogen production method comprising: a biomass gas production step of obtaining the biomass gas by the biomass gas production method according to any one of [1] to [6]; and a hydrogen production step of reforming the biomass gas to produce hydrogen. [8] The hydrogen production method according to [7], wherein the hydrogen production step uses a composite reforming catalyst containing at least one metal element selected from iron, cobalt, platinum, rhodium, molybdenum, zirconium, titanium, cerium, lanthanum, and neodymium.

[0011] [9] A biomass gas production system having a pyrolysis gasification device that uses biomass as a raw material and gasifies it with steam containing metal components to obtain biomass gas.

[10] The biomass gas production system described in [9], wherein the pyrolysis gasification apparatus has a combustion furnace that burns a portion of the biomass and a gasification furnace that obtains the biomass gas from another portion of the biomass and the steam, and the pyrolysis gasification apparatus has a means for supplying exhaust heat generated in the combustion furnace to the gasification furnace.

[11] The biomass gas production system described in [9], wherein the pyrolysis gasification apparatus has a carbonization furnace that carbonizes the biomass to obtain a carbonized material, and a carbonized material gasification furnace that obtains the biomass gas from the carbonized material and the steam.

[12] The biomass gas production system according to any one of [9] to

[11] , which has a steam heating means for heating the steam using exhaust heat generated in the pyrolysis gasification apparatus as a heat source.

[0012]

[13] A hydrogen production system comprising: the biomass gas production system according to any one of [9] to

[12] ; and a hydrogen production device that reforms the biomass gas to produce hydrogen.

[14] The hydrogen production system according to

[13] , wherein the hydrogen production device has a reaction bed filled with a composite reforming catalyst, and the composite reforming catalyst contains at least one metal element selected from iron, cobalt, platinum, rhodium, molybdenum, zirconium, titanium, cerium, lanthanum, and neodymium. [Effects of the Invention]

[0013] The biomass gas production method, hydrogen production method, biomass gas production system, and hydrogen production system of the present invention can reduce by-products such as tar produced during the pyrolysis gasification of biomass, thereby improving the biomass gasification efficiency and the amount of biomass gas produced. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic diagram of a hydrogen production system according to a first embodiment of the present invention. [Figure 2] 1 is a flowchart of a hydrogen production method according to a first embodiment of the present invention. [Figure 3] FIG. 2 is a schematic diagram of a hydrogen production system according to a second embodiment of the present invention. [Figure 4] 4 is a flowchart of a hydrogen production method according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention provides a biomass gas production method characterized by pyrolysis gasification of biomass using high-calorie steam containing metal components, such as geothermal steam. The technology described in this embodiment improves the biomass gasification efficiency and the amount of biomass gas produced, while also enabling the removal of by-products such as tar. The waste heat from the pyrolysis gasification system and the combustion furnace can be utilized by heat exchange means with steam for geothermal power generation (including binary power generation). This provides a biomass gas production method and a hydrogen production method that are environmentally and economically advantageous.

[0016] In the present invention, the biomass used as a raw material is preferably produced or discarded biomass in forestry or agriculture, which has been crushed and dried. Examples of biomass include harvested forest materials such as cedar, pine, and bamboo, agricultural products and by-products such as rice straw and sugarcane, and industrial waste such as construction waste, cotton, and textile products.

[0017] [First embodiment] A first embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a schematic diagram of a hydrogen production system according to this embodiment.

[0018] 1 includes a biomass gas production system 60 and a hydrogen production device 16. The biomass gas production system 60 includes a combustion furnace 9, a pyrolysis gasification device 50 (also referred to as a "pyrolysis gasification furnace"), and a steam-water separator 32. The combustion furnace 9 is connected to an air blower 30 and a pyrolysis gasification system 50. The steam-water separator 32 is connected to a geothermal water reservoir 31 and the pyrolysis gasification system 50. The pyrolysis gasification system 50 is connected to a heat exchanger 18 via a gas separation and purification treatment unit 13. The heat exchanger 18 is connected to a turbine generator 19, a gas holder 14, and a heat exchanger 17. The gas holder 14 is connected to a gas engine power generation system 15. The heat exchanger 17 is connected to the steam-water separator 32. In this embodiment, the pyrolysis gasification apparatus 50 is composed of a gasification furnace main body 1, a gasification furnace heating section 8, a gasification reaction tower 10, and a steam heat exchanger 34. The gasification furnace main body 1 is connected to the gasification furnace heating section 8, the gasification reaction tower 10, and the steam heat exchanger 34. The steam heat exchanger 34 functions as a steam heating means.

[0019] The gasification furnace body 1 has a steam input section 5 for supplying steam 33 containing metal components, such as geothermal steam, into the furnace. The gasification furnace heating section 8 is connected to a biomass input section 4 that supplies biomass 3 for pyrolysis and gasification into the furnace from the top of the furnace. A discharge section 11 for removing solid ash and coke produced by pyrolysis gasification is provided at the bottom of the gasification reaction tower 10. A discharge section 12 for removing the produced biomass gas 2 is provided at the top of the gasification reaction tower 10.

[0020] Next, an example of a hydrogen production method using the hydrogen production system 100 will be described with reference to FIGS. As shown in FIG. 2, the hydrogen production method according to this embodiment includes a biomass gas production process P3 in which biomass is used as a raw material and is gasified with steam containing metal components to obtain biomass gas, and a hydrogen production process P4 in which the biomass gas is reformed to produce hydrogen.

[0021] First, fuel biomass 6 is loaded into the combustion furnace 9 through the upper opening of the combustion furnace 9, and while air is supplied into the combustion furnace 9 by the air blower 30, a portion of the biomass 6 is combusted to generate combustion gas 7 (combustion operation S1). The combustion gas 7 generated in the combustion furnace 9 is supplied to a gasification furnace heating section 8 of the pyrolysis gasification apparatus 50 .

[0022] Next, biomass 3 for pyrolysis and gasification is charged into the gasification furnace body 1 from the biomass charging section 4 of the pyrolysis and gasification apparatus 50 .

[0023] In this embodiment, geothermal steam obtained by separating gas from geothermal water pumped up from a geothermal water reservoir 31 in a steam-water separator 32 is used as the steam 33 containing metal components. The metal component contained in the water vapor 33 includes at least one element selected from the group consisting of sodium, potassium, lithium, calcium, magnesium, strontium, barium, boron, aluminum, and gallium. The metal component contained in the water vapor 33 may include at least one salt selected from the group consisting of carbonates, sulfates, hydrochlorides, and silicates. The content of the salt is preferably 10 to 10,000 mg, more preferably 20 to 1,000 mg, per kg of water vapor.

[0024] The steam 33 is heated in a steam heat exchanger 34 using the exhaust heat WH generated in the combustion operation S1 as a heat source (steam heating step P2). The steam 33 is introduced into the gasification furnace body 1 from a steam introduction section 5 at the bottom of the gasification furnace body 1. As the steam 33, tap water or industrial water can be used directly after softening, or steam obtained by heavy oil combustion boiler treatment can be used as well. In the gasification furnace body 1, the introduced biomass 3 and high-temperature steam 33 are mixed and convected together and uniformly heated, thereby producing biomass gas 2 (gasification operation S2). Since the steam 33 contains metal components, the biomass gas 2 containing reduced by-products such as tar can be obtained.

[0025] The steam 33 supplied into the gasifier body 1 is heated to a high temperature range of 650 to 1200°C, preferably 800 to 1000°C, and then subjected to gasification operation S2. The biomass gas obtained in gasification operation S2 is supplied to the gasifier reaction tower 10. Inside the gasifier reaction tower 10, pyrolysis gasification is promoted by the steam 33 in the high temperature range, and biomass gas 2 containing hydrocarbons such as CH4 and C2H4, as well as H2, CO, and CO2 is produced (pyrolysis gasification step P1).

[0026] In the pyrolysis gasification step P1, biomass (C nH2O m :C for cedar, bamboo, and grass wood 1.42 H2O 0.91 , n, and m are positive numbers.) as the raw material, and steam (HO) as the gasifying agent, the pyrolysis gasification reactions represented by the following equations (1), (2), and (3) occur mainly depending on the temperature inside the gasification furnace reaction tower 10. Temperature inside the gasification reactor 10: 800°C C 1.42 H2O 0.91 +0.38H2O=0.74H2+0.75CO+0.24CH4+0.24C2H4+0.28CO2...Formula (1) Temperature inside the gasification reactor 10: 900°C C 1.42 H2O 0.91 +0.71H2O=1.27H2+0.76CO+0.21CH4+0.02C2H4+0.41CO2...Formula (2) Temperature inside the gasification reactor 10: 1000°C C 1.42 H2O 0.91 +0.89H2O=1.59H2+0.76CO+0.15CH4+0.51CO2...Formula (3)

[0027] To produce hydrogen using the generated biomass gas, it is necessary to adjust the pyrolysis gasification step P1 so that the reactions of the above formulas (1), (2), and (3) proceed smoothly. If oxygen or air is mixed with the steam, the gas calorific value of the biomass gas will decrease due to complete combustion of the biomass, so the steam may be deoxygenated.

[0028] One means for adjusting the pyrolysis gasification step P1 is to control the temperature inside the gasification furnace reaction tower 10 to 800 to 1000°C. The temperature inside the gasification furnace reaction tower 10 is controlled by adjusting the flow rates of the biomass 3 and steam 33 supplied to the gasification furnace body 1, in addition to controlling the temperature and flow rate of the combustion gas 7. By controlling the temperature inside the gasification furnace reaction tower 10 to 800 to 1000°C, the pyrolysis gasification reactions (1) to (3) of the biomass 3 proceed at a preferable gasification conversion rate, and biomass gas 2 is obtained (this is the biomass gas production step P3).

[0029] Soot and dust such as solid ash and coke contained in the biomass gas 2 are removed in a gas separation and purification treatment unit 13 equipped with a cyclone and a bag filter that physically removes tar that is generated as a by-product. The biomass gas 2 passes through the gas separation and purification treatment unit 13 and is stored in a gas holder 14. The biomass gas 2 is supplied to a gas engine power generation unit 15 and / or a hydrogen production unit 16.

[0030] In this embodiment, the biomass charging section 4 is provided at the top of the furnace, and the steam charging section 5 is provided at the bottom of the gasification furnace main body 1. However, the present invention is not limited to this, and the biomass 3 may be supplied from below or from the side of the gasification furnace main body 1. The steam 33 may be supplied from the top or from the side of the gasification furnace main body 1. The biomass and steam may be supplied at one or more locations.

[0031] In this embodiment, the exhaust heat WH of the combustion gas 7 generated in the combustion operation S1 is supplied to a heat exchanger 17. The exhaust heat WH of the biomass gas 2 generated in the pyrolysis gasification step P1 is supplied to a heat exchanger 18. The exhaust heat WH supplied to the heat exchanger 17 or the heat exchanger 18 is used as an additional heat source for geothermal steam (steam heating step P2). The steam after the heat exchange process is input into a turbine generator 19 and used for steam power generation using the exhaust heat.

[0032] When hydrogen H is produced using biomass gas 2, the biomass gas 2 is reformed to produce hydrogen H in a hydrogen production device 16 having a reaction bed filled with a composite reforming catalyst (hydrogen production step P4). The hydrogen production device 16 may be equipped with a booster that increases the gas pressure to a predetermined pressure and a gas-liquid separator that separates the produced hydrogen H. The predetermined pressure may be, for example, 1 to 20 atmospheres (0.1 to 2 MPa). Hydrogen may also be produced within a predetermined temperature range using the exhaust heat of the combustion gas 7 discharged from a heat exchanger 17 as a heat source for the hydrogen production device 16. The predetermined temperature range may be, for example, 250°C to 600°C.

[0033] In the hydrogen production step P4 of this embodiment, a composite reforming catalyst containing at least one metal element selected from iron, cobalt, platinum, rhodium, molybdenum, zirconium, titanium, cerium, lanthanum, and neodymium may be used. In this specification, the term "composite reforming catalyst" refers to a catalyst obtained by mixing a conventional catalyst primarily composed of nickel, ruthenium, or the like with at least one metal element selected from iron, cobalt, platinum, rhodium, molybdenum, zirconium, titanium, cerium, lanthanum, and neodymium. These catalysts may also be porous oxides containing the above metal elements. Porous oxides refer to metal oxides with a large number of fine pores. Examples of porous oxides include zirconia. Composite reforming catalysts can be prepared by conventional impregnation methods using an acetone solution of an acetylacetonato complex of a substance containing the above metal elements or an aqueous solution of various salts (such as nitrates or hydrochlorides). Typically, the prepared catalyst is reduced using hydrogen gas or a reducing agent before being subjected to the biomass gas reforming reaction. However, in the present invention, the composite reforming catalyst may be used in the reforming reaction of biomass gas without being subjected to reduction treatment using hydrogen gas or a reducing reagent.

[0034] In the hydrogen production step P4 of this embodiment, hydrogen is produced by a reforming reaction of the biomass gas 2. In the reforming reaction of the biomass gas 2, the reaction temperature is preferably 250°C to 600°C, more preferably 350°C to 450°C, from the viewpoints of reactivity and thermal efficiency. The reaction pressure is preferably 1 to 20 atmospheres (0.1 to 2 MPa), more preferably 5 to 10 atmospheres (0.5 to 1 MPa).

[0035] In this embodiment, the generated hydrogen H is purified by a PSA (Pressure Swing Adsorption) gas separation device to obtain high-purity hydrogen (hydrogen with a purity of 99.999% or more). The high-purity hydrogen is used for fuel cells in fuel cell vehicles, home power generators, and uninterruptible power supplies (UPS).

[0036] [Second embodiment] A second embodiment of the present invention will be described with reference to FIG. A schematic diagram of a hydrogen production system according to a second embodiment of the present invention is shown in Figure 3. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0037] 3 includes a biomass gas production system 62 and a hydrogen production device 16. The biomass gas production system 62 includes a carbonization furnace 21, a carbonized material gasification furnace 24, and a steam heat exchanger 27. The carbonization furnace 21 is connected to an air blower 30 and a gasification furnace heating section 25 provided in the carbide gasification furnace 24. The steam heat exchanger 27 is connected to the gasification furnace heating section 25, the steam input section 26 of the carbide gasification furnace 24, and a supply source of steam 29. The carbide gasification furnace 24 is connected to a heat exchanger 18 via a gas separation and purification treatment section 13. The heat exchanger 18 is connected to a turbine generator 19, a gas holder 14, and a heat exchanger 17. The gas holder 14 is connected to a gas engine power generation device 15. The heat exchanger 17 is connected to the steam heat exchanger 27. In this embodiment, the pyrolysis gasification system 52 is composed of a carbonization furnace 21 and a carbide gasification furnace 24. The steam heat exchanger 27 functions as a steam heating means.

[0038] Next, an example of a hydrogen production method using the hydrogen production system 200 will be described with reference to FIGS. As shown in Figure 4, the hydrogen production method of this embodiment includes a biomass gas production process P3, which includes a carbonization operation S3 in which biomass is carbonized to obtain a carbonized product, and a carbonized product gasification operation S4 in which biomass gas is obtained from the carbonized product and steam, and a hydrogen production process P4 in which the biomass gas is reformed to produce hydrogen.

[0039] First, woody biomass 20 such as cedar, pine, bamboo, etc. is loaded into the carbonization furnace 21 through the upper opening of the carbonization furnace 21, and air is supplied into the carbonization furnace 21 using an air blower 30, while the woody biomass 20 is partially burned to produce charcoal 22 (carbonization operation S3). The charcoal 22 produced in the carbonization furnace 21 is removed from the lower end of the carbonization furnace 21, subjected to a crushing process, and then fed into a char gasification furnace 24 from an upper opening or a middle opening. The combustion gas 23 generated in the carbonization furnace 21 is supplied to the gasification furnace heating section 25 through an upper opening and heats the inner wall of the carbide gasification furnace 24 to a predetermined temperature. The combustion gas 23 is supplied to the steam heat exchanger 27 through the gasification furnace heating section 25.

[0040] The water vapor 29 contains a metal component. The metal component contained in the water vapor 29 includes at least one element selected from the group consisting of sodium, potassium, lithium, calcium, magnesium, strontium, barium, boron, aluminum, and gallium. The metal component contained in the water vapor 29 may include at least one salt selected from the group consisting of carbonates, sulfates, hydrochlorides, and silicates. The content of the salt is preferably 10 to 10,000 mg, more preferably 20 to 1,000 mg, per kg of water vapor.

[0041] The steam 29 is heated to a predetermined temperature in the steam heat exchanger 27, and then a portion of the steam is supplied from the steam input section 26 into the carbide gasifier 24. The predetermined temperature is, for example, 650 to 1200°C. Inside the carbide gasifier 24, a pyrolysis gasification reaction (C + H2O = CO + H2) between the steam 29 and the carbide 22 and a CO shift reaction (CO + H2O = CO2 + H2) and the like proceed continuously (pyrolysis gasification step P1). As a result, a biomass gas 28, which is a mixed gas of hydrogen (H2), carbon monoxide (CO), methane (CH4), and carbon dioxide (CO2), is produced (carbide gasification operation S4). The produced biomass gas 28 is supplied to the gas separation and purification treatment unit 13 (biomass gas production step P3). Since the steam 29 contains metal components, the biomass gas 28 containing reduced by-products such as tar can be obtained. The biomass gas 28 that has passed through the gas separation and purification processing unit 13 is supplied to a heat exchanger 18 .

[0042] A portion of the steam 29 heated in the steam heat exchanger 27 passes through the heat exchangers 17 and 18 and is supplied to the turbine generator 19 .

[0043] The exhaust heat WH of the combustion gas 23 discharged from the steam heat exchanger 27 is supplied to the heat exchanger 17. The exhaust heat WH of the biomass gas 28 generated in the carbide gasifier 24 is supplied to the heat exchanger 18. As in the first embodiment, the exhaust heat WH supplied to the heat exchanger 17 or the heat exchanger 18 is used as an additional heat source for steam such as geothermal steam in the heat exchangers 17 and 18 (steam heating step P2). The steam after the heat exchange process is input into the turbine generator 19 and used for steam power generation using the exhaust heat.

[0044] The biomass gas 28 produced in the carbide gasification furnace 24 in this embodiment is separated into tar and coke in the gas separation and purification treatment unit 13, as in the first embodiment, and after purification, the gas passes through heat exchangers 18 and 17 in sequence and is stored in the gas holder 14. The biomass gas 28 in the gas holder 14 is supplied to the gas engine power generation device 15 or the hydrogen production device 16 and is used for gas power generation and hydrogen production.

[0045] In this embodiment, as in the first embodiment, hydrogen can be produced at low pressure (for example, 1 MPa or less) and in a low temperature range (for example, below 650°C) by bringing the produced biomass gas 28 into contact with a composite reforming catalyst (hydrogen production step P4). Hydrogen can also be produced in a predetermined temperature range by using the exhaust heat of the combustion gas 23 and biomass gas 28 discharged from the carbonization furnace 21 and carbide gasification furnace 24 as a heating heat source for the hydrogen production device 16. [Example]

[0046] Examples of the present invention are shown below, but the following examples are merely illustrative of the invention and the content of the present invention is not limited to the following examples.

[0047] [Example 1, Comparative Example 1] Geothermal steam containing metal components, obtained through a steam separator for geothermal water pumped from a geothermal water reservoir, was used as the steam for pyrolysis gasification of biomass. Cedar wood pellets (15% moisture content) were fed as biomass into a pyrolysis gasifier and a combustion gas furnace at feed rates of 100 kg / h for gasification and 50 kg / h for combustion, respectively, to conduct pyrolysis gasification experiments. The temperature of the pyrolysis gasifier was 900°C, and the pressure was 1.2 atmospheres (0.12 MPa). The weight ratio of steam (water vapor) to biomass in the pyrolysis gasifier (S / C [kg] / [kg]) was 1.9. Table 1 compares the results of pyrolysis gasification reaction tests on the biomass gasification conversion efficiency and the amount of biomass gas produced in the pyrolysis gas furnace when geothermal steam A (150°C, 0.3 MPa, flow rate 200 kg / h, calorific value 650 kcal / kg) was used as steam containing metal components (Example 1) and when softened tap water was used (Comparative Example 1). In the table, the "fuel gas yield (m 3 / kg) is the amount of fuel gas (H2+CO+CH4+C2H6+CO2) produced per kg of biomass (Nm 3 ) in the table. n H m"(vol%)" refers to the volume percent of volatile long-chain hydrocarbon components, where n (n and m are natural numbers) is 2 or greater. The concentrations of CO, hydrogen, CO2, CH4, and other hydrocarbons in the outlet gas were measured using a micro gas chromatograph (GL Sciences Inc.) filled with Gaskuropack and molecular sieve 13X and a flame ionization detector (FID) gas chromatograph (Shimadzu Corporation). The flow rate of the exhaust gas was measured using a wet gas flowmeter. The production rate of the generated gas was calculated from GC (gas chromatography) analysis of the effluent gas. The gasification conversion rate was calculated using the formula "(total lower heating value of biomass gas) / (lower heating value of input biomass) × 100." The biomass gas production rate was the average value over 2 to 10 hours. The amounts of tar and char produced were determined by measuring the weight of the filtered material after the biomass supply was stopped. The metal components of geothermal steam A were Na: 600 mg / kg, K: 95 mg / kg, Mg: 35 mg / kg, Ca: 65 mg / kg, and Sr: 15 mg / kg. The metal components of geothermal steam A were measured using ion chromatography. The metal and salt components in the steam obtained from softened tap water were Na: 8 mg / kg, K: 3 mg / kg, Ca: 6 mg / kg, Mg: 3 mg / kg, Al: 0.2 mg / kg, and B: 0.5 mg / kg, in concentrations per kg of steam. The metal and salt components in the steam obtained from softened tap water were measured using ion chromatography and inductively coupled plasma (ICP) atomic emission spectroscopy. These results show that when using geothermal steam containing metal components in a biomass gasification furnace, the gasification conversion rate, the amount of fuel gas (biomass gas) produced, and the gas heating value (lower gas heating value) are significantly improved compared to when tap water is used, and the amount of tar produced as a by-product is reduced.

[0048] [Table 1]

[0049] [Examples 2 to 3] Similar to Example 1, pyrolysis gasification of biomass was carried out using high-temperature steam B and C containing metal components. The temperature of the pyrolysis gasifier was 1000°C, and the pressure was 1 atmosphere (0.1 MPa). The molar ratio of steam (water vapor) to carbon (S / C) in the pyrolysis gasifier was 1.5. Table 2 shows the gas component composition of the fuel gas, gasification conversion rate, fuel gas yield, etc. when steam B (Example 2: 165°C, 0.35 MPa, flow rate 210 kg / h, calorific value 650 kcal / kg) and steam C (Example 3: 180°C, 0.5 MPa, flow rate 200 kg / h, calorific value 670 kcal / kg). These results demonstrate that when metal-containing steam B and C were used in pyrolysis gasification, the gasification conversion rate, fuel gas yield, and gas calorific value (lower gas calorific value) were increased compared to Comparative Example 1, in which ordinary water was used. The amount of tar produced was significantly reduced. The metal components contained in steam B were measured at concentrations per kg of steam of 650 mg / kg Na, 150 mg / kg Li, 20 mg / kg Ca, 120 mg / kg B, and 230 mg / kg Mg. Meanwhile, the metal components contained in steam C were measured at concentrations per kg of steam of 380 mg / kg Na, 120 mg / kg K, 85 mg / kg Mg, 130 mg / kg Al, and 78 mg / kg Ba. The metal components contained in steam B were measured using tap water after softening treatment in the same manner as for the metal and salt components in steam. The metal components contained in steam C were measured using the same method as for the metal components contained in geothermal steam A.

[0050] [Table 2]

[0051] [Examples 4 to 5, Comparative Example 2] A steam reforming reactor was filled with composite reforming catalyst A (8% Ni, 10% Ru, 1% Pt, 5% Ce, 1% Ti, 2% Co / Al2O3) or composite reforming catalyst B (2% Fe, 10% Ru, 1% Rh, 5% Zr, 2% Mo, 2% La / Al2O3) (weight %), and a reforming reaction was carried out using biomass gas (45% H2, 8% CH4, 25% CO, 21% CO2, 1% C2H6) obtained by pyrolysis gasification in Example 1 (Examples 4 and 5). The biomass gas at the outlet of the pyrolysis gasifier was washed with water and purified before being introduced into the steam reforming reactor. The reaction conditions were a reaction temperature of 250°C and a pressure of 0.5 MPa. Table 3 shows the results of a hydrogen production test using biomass gas obtained by biomass pyrolysis gasification equipped with a steam reforming reactor. In the table, the "hydrogen yield (Nm 3 / h) represents the amount of hydrogen with a purity of 99.999% or higher. As shown in Table 3, the hydrogen yield after PSA gas purification treatment after gas-liquid separation of the produced hydrogen gas was 690 Nm 3 / h (Example 4), 645 Nm 3 / h (Example 5). When the commercial catalyst (25% Ni, 5% Ru / Al2O3) shown in Comparative Example 2 was used (540 Nm 3 It was demonstrated that the hydrogen yield and hydrogen conversion rate were increased when using Catalyst A of Example 4 and Catalyst B of Example 5 compared to the case where the catalyst was used in Example 4 / h.

[0052] [Table 3]

[0053] [Experimental Example 1] In Example 1, geothermal steam (flow rate 2 t / h) for steam power generation was used for reheating in heat exchangers connecting the combustion gas (1000-1200°C) discharged from a pyrolysis gasifier using cedar pellets and the biomass gas (650-800°C) to the gasifier outlet and furnace heating section, respectively. Under the same operating conditions as in Example 1, steam turbo power generation was performed using high-calorie steam obtained by utilizing the waste heat of the combustion gas from the pyrolysis gasifier and the biomass gas (Experimental Example 1). The results showed that the power generation efficiencies when utilizing the waste heat from the pyrolysis gasifier and when not utilizing the waste heat were 16% and 15%, respectively, and the net power output was 273 kWe and 213 kWe. It was found that utilizing the waste heat from the biomass gasifier increased geothermal power generation output by 30%.

[0054] [Example 6, Comparative Example 3] Biomass pellets (15% moisture content) were fed into the high-temperature carbonization furnace shown in Figure 3 at a feed rate of 150 kg / h to produce 45 kg / h of char with a char recovery rate of 35%. The recovered char was mechanically crushed and the resulting char was fed into the pyrolysis gasification furnace from the top. Table 4 compares the pyrolysis gasification reaction results for the char gasification conversion rate, generated gas volume, and gas composition when steam D containing metal components (Example 6: 150°C, 0.35 MPa, flow rate 200 kg / h, heat content 658 kcal / kg) was fed into the pyrolysis gasification furnace and when tap water was used (Comparative Example 3). The temperature of the pyrolysis gasification furnace was 950°C, and the pressure was 1.2 atm (0.12 MPa). The molar ratio (S / C) of steam (water vapor) to char in the pyrolysis gasification furnace was 1.2. These results demonstrated that when steam containing metal components was used in a two-stage biomass pyrolysis gasifier, the gasification conversion rate, fuel gas yield, and lower gas calorific value were increased compared to Comparative Example 3, which used tap water. The H2 / CO molar ratio of the product gas was 4.3 when steam D was used, which was an increased hydrogen production molar ratio compared to 2.5 when tap water was used. In addition, the biomass gasification conversion efficiency improved to 68%. The concentrations of metal components contained in steam D were Na: 600 mg / kg, Li: 80 mg / kg, Sr: 15 mg / kg, Ga: 20 mg / kg, and B: 12 ​​mg / kg per kg of steam. The concentrations of metal components contained in steam D were measured using the same method as for the metal and salt components in steam using softened tap water. The concentrations of metal components in the tap water used were, per kg of steam, Na: 6 mg / kg, K: 2 mg / kg, Ca: 5 mg / kg, Mg: 2 mg / kg, and Al: 0.1 mg / kg. The concentrations of metal components in the tap water were measured using the same method as for the metal components contained in geothermal steam A.

[0055] [Table 4]

[0056] According to the present invention, it has been found that by using steam containing metal components, such as geothermal steam, in the pyrolysis gasification of biomass such as wood and agricultural waste, it is possible to improve the biomass gasification efficiency and the yield of fuel gas and hydrogen. This makes it possible to provide an economical method for pyrolysis gasification of biomass and hydrogen production that reduces environmental impact. [Industrial Applicability]

[0057] According to the present invention, it is possible to reduce by-products such as tar during pyrolysis gasification of biomass, thereby improving the efficiency of biomass gasification and the amount of biomass gas produced. [Explanation of symbols]

[0058] 1 Gasification furnace body 2. Pyrolysis gas (biomass gas) 3. Biomass for pyrolysis gasification 4. Biomass input section 5 Steam input section 6. Biomass for fuel 7 Combustion Gas 8 Gasifier heating section 9 Combustion furnace 10 Gasification reactor 11 Discharge section 12 Biomass gas exhaust section 13 Gas separation and purification processing section 14 Gas Holder 15 Gas engine generator 16 Hydrogen production equipment 17 Heat exchanger 18 Heat exchanger 19 Turbine generator 20 Woody biomass 21 Carbonization furnace 22 Carbide 23 Combustion gas 24 Charcoal Gasifier 25 Gasifier heating section 26 Steam input section 27 Steam heat exchanger 28 Biomass gas 29 Water Vapor 30 Air Blower 31 Geothermal water reservoir 32 Steam water separator 33 Water Vapor 34 Steam heat exchanger 50 Pyrolysis gasification equipment 52 Pyrolysis gasification equipment 60 Biomass Gas Production System 62 Biomass Gas Production System 100 Hydrogen Production System 200 Hydrogen Production System P1 Pyrolysis gasification process P2 Steam heating process P3 Biomass gas production process P4 Hydrogen production process S1 Combustion Operation S2 Gasification Operation S3 Carbonization Operation S4 Charcoal gasification operation WH heat dissipation

Claims

1. a biomass gas production process for obtaining the biomass gas by a biomass gas production method, the biomass gas production process including a pyrolysis gasification process for obtaining the biomass gas by gasification using biomass as a raw material with steam containing metal components; a hydrogen production step of reforming the biomass gas to produce hydrogen, In the pyrolysis gasification step, the temperature of the pyrolysis gasification reaction is controlled to 800°C to 1000°C, A method for producing biomass gas and hydrogen, wherein the metal components contained in the steam are, in terms of concentration per 1 kg of steam, any one of the following (A) to (D): (A) Na: 600mg / kg, K: 95mg / kg, Mg: 35mg / kg, Ca: 65mg / kg, Sr: 15mg / kg (B) Na: 650mg / kg, Li: 150mg / kg, Ca: 20mg / kg, B: 120mg / kg, Mg: 230mg / kg (C) Na: 380mg / kg, K: 120mg / kg, Mg: 85mg / kg, Al: 130mg / kg, Ba: 78mg / kg (D) Na: 600mg / kg, Li: 80mg / kg, Sr: 15mg / kg, Ga: 20mg / kg, B: 12mg / kg

2. 2. The method for producing biomass gas and hydrogen according to claim 1, wherein the metal component comprises at least one element selected from the group consisting of sodium, potassium, lithium, calcium, magnesium, strontium, barium, boron, aluminum, and gallium.

3. 3. The method for producing biomass gas and hydrogen according to claim 1, wherein the content of the metal component is 10 to 10,000 mg per 1 kg of the water vapor.

4. the pyrolysis gasification step includes a combustion operation of burning a portion of the biomass and a gasification operation of obtaining the biomass gas from another portion of the biomass and the steam, The method for producing biomass gas and hydrogen according to any one of claims 1 to 3, wherein the gasification operation uses exhaust heat generated in the combustion operation as a heat source.

5. The method for producing biomass gas and hydrogen according to any one of claims 1 to 4, wherein the pyrolysis gasification process includes a carbonization operation of carbonizing the biomass to obtain a carbonized product, and a carbonized product gasification operation of obtaining the biomass gas from the carbonized product and the steam.

6. The method for producing biomass gas and hydrogen according to any one of claims 1 to 5, wherein exhaust heat generated in the pyrolysis gasification step is used as a heat source in a steam heating step for heating steam.

7. The method for producing biomass gas and hydrogen according to any one of claims 1 to 6, wherein the hydrogen production step uses a composite reforming catalyst containing at least one metal element selected from iron, cobalt, platinum, rhodium, molybdenum, zirconium, titanium, cerium, lanthanum, and neodymium.

Images