JP3980382B2 - Biomass pyrolysis method and apparatus - Google Patents

Description

【００２６】
【発明の効果】
本発明による、ガス化顕熱を熱分解に組み合わせる方法及びその装置することで、高効率なバイオマスのガスエネルギー及び液エネルギーへの転換を可能とする。
【図面の簡単な説明】
【図１】 バイオマス熱分解プロセスフロー。
【図２】 熱分解温度と固形分残渣の関係。
【図３】 温度制御性。
【符号の説明】
１…熱分解反応部
２…バイオマス熱分解反応部供給装置
３…バイオマス
４…接続部
５…高温ガス
６…ガス化部
７…酸素
８…：水蒸気
９…固気分離工程
１０…バイオマスチャー
１１…液分離器
１２…タール
１３…ガス
１４…ガス燃料
１５…炭素質原料
１６…バイオマスガス化部供給装置
１７…バイオマスチャー供給装置
１８…制御用温度計。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for rapidly pyrolyzing biomass using high-temperature gas sensible heat.
[0002]
[Prior art]
Responses to global warming issues include the development and commercialization of new energy, a shift to low carbon dioxide generation energy, an increase in the nuclear power ratio, efficient and rational use of existing primary energy, unused energy and waste energy It is promoted by the use of. Biomass, in particular, is carbon neutral, and is actively used to achieve international commitments at the Conference of the Parties to the Framework Convention on Climate Change (COP 3-6, COP), replacing petroleum, coal, etc. It can be said that it is a necessary resource. Biomass is a collective term for biomass, and according to FAO (United Nations Food and Agriculture Organization), agriculture (wheat straw, sugar cane, rice bran, vegetation, etc.), forestry (paper waste, sawn timber, thinned wood, wood-burning forest) Etc.), livestock (livestock waste), fisheries (fishery processing residue), waste (raw garbage, RDF (refined solid fuel), garden trees, construction waste, sewage sludge), etc. The
[0003]
When energy recovery from biomass and energy conversion are considered, steam is usually generated by sensible heat of generated gas from combustion, and a low efficiency method is used in which steam is recovered as electric power. This is because biomass generally contains a lot of water and has a low calorific value, so there is only a choice of combustion due to the lack of heat required for pyrolysis and gasification, so external heat (heat compensation by other fuels) ), There are many processes that do not hold. Therefore, in order to recover energy from biomass and use it effectively, a method with high conversion efficiency is essential. Recently, as seen in Japanese Patent Application Laid-Open No. 11-302665, “Gasification Method Using Biomass and Fossil Fuel”, a technique for increasing the energy conversion efficiency of biomass by using fossil fuel together has been proposed. It came to be seen.
[0004]
[Problems to be solved by the invention]
When biomass is partially oxidized (gasified) with oxygen and used as a gas fuel or chemical raw material, the conventional general index is cold gas efficiency ((product latent heat / biomass latent heat) x 100). The value (upper limit value) is about 80%. Minus factors such as moisture, soot generation, irrecoverable dissipated heat, etc. are added to this, and the actual efficiency is greatly reduced to about 60 to 75%. Although moisture can be recovered by heat recovery equipment, it works in the direction of lowering the temperature of the gasification part, thereby lowering the reaction rate itself and causing efficiency reduction.
[0005]
Accordingly, an object of the present invention is to provide a method for effectively using the amount of heat of biomass in a reaction form suitable for biomass by selecting a rapid pyrolysis method as an efficient energy conversion method.
[0006]
[Means for Solving the Problems]
The present invention is an effective method for solving the above problems,
1) Using a biomass pyrolysis apparatus comprising a gasification section, a biomass pyrolysis reaction section, and a connection section connecting the gasification section and the pyrolysis reaction section, using biomass as a pyrolysis raw material, Or a biomass pyrolysis method for obtaining a product of gas, tar and char by a pyrolysis reaction at a pyrolysis temperature of 500 to 800 ° C. in the pyrolysis reaction part of the spouted bed, wherein the gas is used as a heat source for the pyrolysis reaction In the gasification section, the biomass or the biomass and any one or more of biomass char, gas fuel, and carbonaceous raw material is used as a gasification raw material, and is obtained by gasification with oxygen or oxygen and water vapor at 800 ° C or higher. Biomass pyrolysis method using high temperature gas,
2) The biomass pyrolysis method according to 1), wherein the pyrolysis temperature is adjusted by changing a supply amount of the biomass pyrolysis raw material according to a heat quantity of the high-temperature gas.
3) The biomass pyrolysis method according to 1), wherein the temperature of the pyrolysis reaction part is detected, and the supply amount of the biomass pyrolysis raw material is adjusted so that the detected temperature becomes a set value. Become.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In this specification, the definition about biomass is based on the said FAO definition. Among the products produced when pyrolyzing biomass, the solid content is biomass char, and the component that is liquid at room temperature is tar. Biomass char is an excellent carbonaceous material with a high carbon content. The gas fuel is a gas fuel that is usually available, such as natural gas or liquefied petroleum gas. The carbonaceous raw material is a solid fuel or a liquid fuel used for heating, such as coal, petroleum, and heavy oil.
[0008]
FIG. 1 shows an example of a biomass pyrolysis process flow to which the present invention is applied. In addition, the equipment configuration required at least to exhibit the effect of the present invention is the biomass pyrolysis reaction section 1 and the gasification section 6 and the connection section 4 connecting them. Biomass 3 is supplied to the biomass pyrolysis reaction section 1 by a biomass pyrolysis reaction section supply device 2. The supplied biomass is rapidly heated and pyrolyzed by the high-temperature gas 5 of 800 ° C. or more from the connection portion 4. Regarding the high temperature gas temperature, when it is less than 800 ° C., the gas sensible heat necessary for the thermal decomposition is insufficient. The upper limit is not particularly specified, and may be set as appropriate in consideration of equipment restrictions (furnace materials, etc.) due to high temperatures. However, from the viewpoint of the dissipated heat that increases as the furnace temperature increases and the stability of the furnace wall component that increases in fluidity as the temperature increases, the temperature is preferably 1700 ° C. or less, and preferably 1600 ° C. or less.
[0009]
Pyrolysis is carried out in an air flow layer or a spouted bed so that the reactant (biomass) can receive sufficient heat. The airflow layer is a system in which solid (in this case, biomass) is strongly influenced by the gas flow and behaves almost the same as the gas flow. The spouted layer is a particle circulation with a balance between the propulsive force (resistance) by gas flow and gravity This is a system with a retention part. The heavier the particles, the longer the residence time in the circulation. The airflow layer and the spouted layer are selected because the system focuses on the progress of the reaction and has better contact (dispersibility) with the hot gas than the fixed bed or fluidized bed.
[0010]
Moreover, the preferable thermal decomposition reaction temperature range in this invention is 400 to 1000 degreeC irrespective of the kind of biomass, For example, the volatile matter (about 83 mass% -dry) in building materials for houses is in this temperature range. Almost converts to gas and tar. At a thermal decomposition temperature of less than 400 ° C., the so-called unreacted component with insufficient reaction increases. Moreover, in the case of the thermal decomposition temperature exceeding 1000 degreeC, the soot reaction which advances at high temperature increases, and solid content residue yield increases. Furthermore, a temperature range of 500 ° C to 800 ° C is more preferable among 400 ° C to 1000 ° C. Although there is no problem in terms of heat balance, a part of unreacted components is observed at temperatures below 500 ° C., and soot is observed at temperatures exceeding 800 ° C.
[0011]
FIG. 2 shows the relationship between the yield of solid residue obtained by pyrolyzing biomass (based on biomass mass on a dry basis) and the pyrolysis temperature. The value obtained by subtracting the solid residue yield from 100% is the amount of gas and tar, and the lower the solid residue yield is, the more effective conditions are converted to gas and tar. Thus, the range of 400 ° C. to 1000 ° C. shows an almost constant low solid content yield (11 to 15% by mass), which is advantageous for the large conversion to gas and tar.
[0012]
In this process, the pyrolysis temperature is uniquely determined by the balance between high-temperature gas sensible heat and the amount of biomass supplied. That is, the remaining heat obtained by subtracting reaction heat such as thermal decomposition and heat dissipated from the sensible heat brought in by the high-temperature gas is distributed to the product containing the gas and biomass residue, and the final temperature is determined. Therefore, for example, when the sensible heat of high-temperature gas is constant, the pyrolysis temperature can be adjusted by utilizing the fact that the pyrolysis temperature decreases when the biomass input is increased and the pyrolysis temperature increases when the input is decreased. Is possible.
On the other hand, the same effect can be obtained by changing the high temperature gas sensible heat, but due to the difficulty of controllability of the partial gasification reaction by oxygen and water vapor, and the fluctuation of the gas flow due to the fluctuation of the high temperature gas amount. It has an adverse effect on the reaction and is not suitable for actual operation.
[0013]
Furthermore, by detecting the pyrolysis reaction part temperature with the control thermocouple 18 and changing the biomass supply amount based on the temperature (if the sensible heat of the high temperature gas is constant, the pyrolysis temperature If the input is reduced, the thermal decomposition temperature increases.), There is a method of adjusting to the set temperature. This detects the thermal decomposition temperature and adjusts it to the thermal decomposition temperature set by changing the supply amount, so that stable operation of thermal decomposition can be achieved.
[0014]
The high-temperature gas 5 as a heat source for the thermal decomposition reaction is produced by partially oxidizing the biomass 7 with oxygen 7 or oxygen 7 and water vapor 8 in the gasification section 6. Gasification proceeds sufficiently with oxygen 7 alone. When steam is used in combination, gas composition adjustment, especially when a large amount of hydrogen is required (hydrogen gas is generated by shift reaction), or the thermal decomposition temperature must be changed greatly in units of 100 ° C for operation change. When gas sensible heat fluctuation is necessary (used as a heat medium. Although there is a means to change the operation of the gasifier, the temperature of the gasifier varies, so steam is also effective from the point of control). The connecting part 4 plays a role of separating the reaction between the pyrolysis reaction part 1 and the gasification part 6, and the pyrolysis reaction part 1 has a high-temperature reduction from 800 ° C. to 1700 ° C. mainly composed of carbon monoxide and hydrogen. Gas (hot gas 5) flows in.
[0015]
When biomass is used as a gasification raw material as the high-temperature gas 5, when the high-temperature gas 5 is less than 800 ° C., insufficient sensible heat of gas necessary for pyrolysis, generation of unburned matter due to a decrease in the gasification reaction rate, etc. This reduces the efficiency of the gasification reaction. Further, the gasification temperature exceeding 1700 ° C. causes restrictions on the heat dissipated by the high temperature, the stability of the furnace material, and the like, and the gasification reaction efficiency decreases due to a large amount of soot generation.
[0016]
In addition, any one or more of biomass char, gas fuel, and carbonaceous raw material may be used in combination with biomass as a gasification raw material. In this case, in the range of 800 ° C. to 1700 ° C., among the carbonaceous raw materials, the high ash melting point (1300 ° C. or higher) raw material represented by coal maintains the gasifier temperature at 1300 ° C. to 1700 ° C. It is necessary to prevent troubles such as high temperature operation, so the efficiency of the gasification furnace part is slightly reduced, but the carbonaceous raw material (1300 ° C) with low melting point of biomass, biomass char, gas fuel, ash Can be operated at a gasification temperature of less than 1300 ° C., and heat can be used without waste.
[0017]
In particular, when using biomass char discharged after pyrolysis as a gasification raw material, attention must be paid to the possibility of soot mixing. This is because the soot produced in the process of partial oxidation reaction in the gasifier and the soot produced in the process of high-temperature pyrolysis in the pyrolysis section are recovered together with the biomass char in the solid-gas separation step. Both soots are less likely to proceed with the gasification reaction and are factors that reduce the overall efficiency of the process, so the pyrolysis temperature and gasification temperature should be set appropriately and optimally for the purpose of suppressing soot formation. desirable.
[0018]
In order to achieve a clear separation of the reaction, the smallest cross-sectional area of the cross-sectional area of the connection part 4 is smaller than the cross-sectional area of the flow path in the vicinity of the connection part with the connection part 4 of the pyrolysis reaction part 1 The smaller one is preferable, and more desirably {[the smallest cross-sectional area of the flow path at the connecting part / the cross-sectional area of the pyrolysis reaction part side in the vicinity of the connecting part between the pyrolysis reaction part and the connecting part]} × 100 (cross-sectional area ratio) ) Is preferably 75% or less from the viewpoint of particle separability. These have the effect of preventing inflow of biomass particles into the gasification unit 6, that is, backflow, and preventing an increase in unburned biomass due to oxygen shortage due to the carbon source entering the gasification unit 6. In the gasification unit 6, in order to reduce the oxygen consumption of the entire process and increase the heat generation amount of the product, a partial oxidation reaction is performed instead of complete combustion.
[0019]
The pyrolyzed biomass is converted into gas, tar, and char mainly composed of volatile matter. Only the biomass char 10 is separated from this mixture in the downstream solid-gas separation step 9. Further downstream, tar 12 and gas 13 are separated by liquid separator 11. As the gasification raw material, biomass 3, biomass char 10, gas fuel 14, and carbonaceous raw material 15 are used. Any can be used as long as high-temperature reducing gas can be generated, but when the external input energy is minimized, it is preferable to use the biomass char 10 in its entirety. In addition, when a shortage of heat occurs due to operating conditions, biomass 3 can be used, and gas fuel 14 and carbonaceous raw material 15 can be used supplementarily. The biomass char 10 is supplied from the biomass char supply device 17, and the biomass 3 is supplied from the biomass gasification unit supply device 16.
[0020]
【Example】
Next, the present invention will be described in more detail with reference to examples.
[0021]
Example 1
Table 1 shows the efficiency comparison with the prior art. The prior art compared is only the gasification technique, and the example of the present invention is a system combining gasification with thermal decomposition. In this system, the same biomass as the pyrolysis raw material is used as the gasification raw material. The thermal decomposition temperatures are 500 ° C. and 800 ° C., which are the boundary temperatures in the preferred thermal decomposition temperature range, and in this temperature range (500 to 800 ° C.), an effect equal to or higher than the present result can be obtained (FIG. 2). Than). The gasification temperature could be set to an efficient temperature of 1200 ° C. because there is no worry of ash adhesion trouble. Product latent heat (equivalent to cold gas efficiency of gasification) that can be recovered from raw biomass (pyrolysis + gasification) is 85 to 88%, compared with conventional gasification (partial oxidation: about 80% at maximum) Even so, it is very efficient. This means that a minimum amount of oxygen is used to convert biomass to energy (only 50% to 70% of the prior art is used per ton of biomass) and consequently less This is because the gasification temperature can be set to 1200 ° C despite the amount of oxygen, and the loss of heat dissipation, etc. has been reduced, and the cold gas efficiency has improved by 5% or more compared to the conventional technology, which is also very advantageous from an industrial viewpoint. It was a big result.
[0022]
Example 2
As a method for controlling the pyrolysis temperature, the pyrolysis temperature is calculated according to the amount of heat of the high-temperature gas, that is, the amount of heat determined by the operating conditions of the gasification unit, using the characteristic that is uniquely determined by the balance between the high-temperature gas sensible heat and the amount of biomass supplied. A method for adjusting the pyrolysis reaction temperature by supplying the amount of biomass that has been produced from the biomass pyrolysis supply device 2 will be described. Gasification raw material amount, industrial analysis value [volatile content 83.2% by mass-dry, ash content 1.4% by mass-dry, moisture 17.4% by mass], elemental analysis value [C: 50.4% by mass-dry, H: 5.8 mass% -dry, O: 42.1 mass% -dry]), and the material balance and heat balance from the input oxygen amount, input water vapor amount, and gasifier heat release amount, the predetermined gasification temperature The product (hot gas component) at the time of the shift reaction equilibrium in is estimated, and the gas sensible heat is calculated. Based on the sensible heat of the gas, the biomass amount for obtaining the target pyrolysis temperature was calculated from the specific heat of biomass and the moisture content.
[0023]
For example, in the case of biomass gasification amount 70kg / hr, oxygen 40Nm3 / hr, heat dissipation 8%, gas sensible heat is calculated using thermal calculation method usually used in chemical industry process and gasification process such as coal, and pyrolysis When the target temperature value is 700 ° C., the amount of pyrolyzed biomass may be 90 kg / hr from the biomass specific heat and the amount of water used. Moreover, when it is desired to change the target value of the pyrolysis temperature to another temperature, the amount of pyrolysis biomass can be calculated by the same method.
[0024]
Example 3
The temperature of the pyrolysis reaction section was detected by the control thermocouple 18 and the biomass supply amount was changed based on the temperature. FIG. 3 shows an example of temperature controllability in this method. Although it is an example of a short time, although there were fluctuation factors of the pyrolysis biomass supply amount and the gasification biomass supply amount with respect to the set temperature, it was possible to control stably.
[0025]
[Table 1]

[0026]
【The invention's effect】
The method and apparatus for combining gasified sensible heat with pyrolysis according to the present invention enables conversion of highly efficient biomass into gas energy and liquid energy.
[Brief description of the drawings]
FIG. 1 is a biomass pyrolysis process flow.
[Fig. 2] Relationship between thermal decomposition temperature and solid residue.
[Fig. 3] Temperature controllability.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Pyrolysis reaction part 2 ... Biomass pyrolysis reaction part supply apparatus 3 ... Biomass 4 ... Connection part 5 ... High temperature gas 6 ... Gasification part 7 ... Oxygen 8 ...: Steam 9 ... Solid-gas separation process 10 ... Biomass char 11 ... Liquid separator 12 ... Tar 13 ... Gas 14 ... Gas fuel 15 ... Carbonaceous raw material 16 ... Biomass gasification unit supply device 17 ... Biomass char supply device 18 ... Control thermometer.

Claims (3)

Using a biomass pyrolysis apparatus comprising a gasification section, a biomass pyrolysis reaction section, and a connection section connecting the gasification section and the pyrolysis reaction section, using biomass as a pyrolysis raw material, an air flow layer or a jet A biomass pyrolysis method for obtaining a product of gas, tar and char by a pyrolysis reaction at a pyrolysis temperature of 500 to 800 ° C. in the pyrolysis reaction part of a layer,
As a heat source for the pyrolysis reaction, in the gasification unit, any one or more of biomass, biomass, biomass char, gas fuel, and carbonaceous raw material is used as a gasification raw material, and gas is supplied with oxygen or oxygen and water vapor. Biomass pyrolysis method using a high-temperature gas of 800 ° C. or higher obtained by conversion.   The biomass pyrolysis method according to claim 1, wherein the pyrolysis temperature is adjusted by changing a supply amount of the biomass pyrolysis raw material according to a heat quantity of the high-temperature gas.   The biomass pyrolysis method according to claim 1, wherein the temperature of the pyrolysis reaction part is detected, and the supply amount of the biomass pyrolysis raw material is adjusted so that the detected temperature becomes a set value.

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