JP2007186651A - Method for treating organic matter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein when a gasifiable raw material chiefly composed of organic matters such as biomass such as variety of grass (rice and bamboo) of the Poaceae family, organic wastes (such as waste plastics, animal dung, and waste wood from buildings) are gasified, clogging, coking, etc., by e.g., softened/molten substances, foaming substances, etc., formed during heat decomposition occur in the apparatus. <P>SOLUTION: It is possible to continuously operate a gasifying furnace without any operation troubles by foaming the easily foamable gasifiable raw material once by decomposition by previous heat treatment, grinding the product to adjust its particle diameter, and feeding the previously heat-treated product into the gasifying furnace. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

In the present invention, in the case of gasifying a gasification raw material mainly composed of biomass such as rice plants (rice, bamboo) and woody materials, and organic matter such as organic waste, the gasification raw material is subjected to pretreatment pyrolysis. The present invention relates to a method for eliminating problems such as blockage and coking in the apparatus caused by softening / melting substances, foaming substances, etc. generated during pyrolysis by gasification after the process.

In the present invention, organic waste refers to combustible waste (paper, firewood, fiber, wood, bamboo, plastic, rubber), industrial waste among general waste classified by the Waste Disposal Law. Among them are waste plastic, organic sludge, paper waste, wood waste, textile waste, animal and vegetable residues, rubber waste, and animal manure. The substance contains carbon and hydrogen as constituent elements, and is not limited to the substance as long as it is an organic substance containing carbon and hydrogen.

When an organic substance is heated in an environment where oxygen is not present, thermal decomposition proceeds through the following steps. In the organic matter excluding plastic, in general, in a temperature range of about 60 to 200 ° C., moisture is evaporated and thermal decomposition of the organic matter starts. In a material with a hemicellulose structure, this thermal decomposition begins, and the high-molecular component that is vulnerable to heat breaks down and becomes a low molecule.

In the initial pyrolysis stage, pyrolysis products containing organic acids such as wood vinegar and bamboo vinegar, alcohols, phenols and the like are generated. There are organic substances that show a foamed state in this thermal decomposition stage. In these states, the pyrolysis product becomes a medium, and solid particles in the pyrolysis process may be fused to each other. As a result, the solid particle size may increase in the apparatus, causing clogging troubles, and foamed particles may be fused to the apparatus wall surface, causing caulking troubles.

When organic substances other than plastic are further heated, cellulose and lignin are generally thermally decomposed in a temperature range of about 150 to 450 ° C., and most of them are decomposed at high temperatures.

When an organic substance other than plastic is heated to a higher temperature, carbonization generally proceeds further in a temperature range of about 450 ° C. or higher. In the state where the carbonization has progressed, the solid particles (carbides) are not fused together.

On the other hand, in the case of plastic, the state of thermal decomposition differs depending on the type. In thermoplastics (polypropylene, polyethylene, polystyrene, vinyl chloride, etc.), softening and melting begin in a temperature range of about 150 to 250 ° C.

When the thermoplastic is heated to about 250 to 450 ° C., thermal decomposition proceeds, and at higher temperatures, carbonization proceeds. In the initial stage of the thermal decomposition, a foaming phenomenon may occur, and adhesion to the wall surface of the apparatus occurs. If heating is continued to a higher temperature while the molten plastic is still attached to the wall surface, carbonization proceeds and causes troubles such as coking.

Regarding the carbonization of organic substances, details of characteristics are introduced in Non-Patent Document 1, for example. The thermal decomposition characteristics of waste plastics are introduced in Non-Patent Document 2, for example. Further, for example, Patent Document 1 proposes respective methods and apparatuses for rubber waste, Patent Document 2 for organic sludge, and Patent Document 3 for a thermal decomposition apparatus. However, the conventionally proposed carbonization method and apparatus do not describe the softening / melting phenomenon of the raw material to be carbonized and the countermeasures.

Otani Sugiro, Sanada Yuzo, “Basics of Carbonization Engineering”, Ohmsha, 1980, p. 1-58 Japan Plastics Promotion Association, “A collection of examples of effective use of waste plastics (its active use and development of applications)”, Chemical Engineering Co., Ltd., 1972, p. 159-223

JP-A-8-159430 JP-A-9-47795 JP-A-9-217910

When gasifying organic substances, as a method of supplying the heat necessary for the gasification reaction, a part of the organic substance that is the gasification raw material is combusted and the combustion heat generated at this time is used as the gasification reaction heat. There is a gasification method. In this method, carbon dioxide generated at the time of combustion is mixed in the gasification product gas, so the calorific value of the product gas decreases, so if a high calorific value gas is required, the partial oxidation gasification method Is not preferred.

As a supply gas medium for heat necessary for pretreatment pyrolysis, the oxygen gas concentration is 10 vol. There is a method of supplying a heating gas of not more than% as a medium. Generally, when an organic substance is heat-treated in an atmosphere where oxygen is present, the organic substance is ignited. Ignition conditions vary depending on the type of organic matter, heating temperature, and oxygen concentration, but the oxygen concentration is about 10 vol. Less than% makes it difficult to ignite. Combustion exhaust gas is generally used as a heating gas having a low oxygen concentration. In this method, since a combustion reaction due to residual oxygen may proceed, it is preferable to supply a heating gas not containing oxygen gas as a medium. In this case, a heating gas such as water vapor, nitrogen, carbon dioxide is used.

On the other hand, there is an indirect heating gasification method in which necessary gasification reaction heat is supplied by external heating of a gasification furnace. In this method, since carbon dioxide generated during combustion does not coexist with the gasification product gas, a gasification product gas having a high calorific value of about 4,000 (kcal / Nm ³ ) or more can be obtained.

In the case of this indirect heating gasification method, if a gasification raw material that has not been subjected to pretreatment pyrolysis is supplied into the gasification furnace, the following problems may occur. That is, in the process of raising the temperature of the gasification raw material from the normal temperature to the high temperature gasification state, the solid particles in the foamed state are fused to each other. As a result, this becomes a cause of operation trouble of the apparatus.

Among the gasification raw materials, in particular, biomass such as grasses (rice, bamboo, etc.) and organic matter such as waste containing plastics are heated from the normal temperature to a high temperature gasification state. In the process, it tends to become foamed.

Therefore, in the case of gasifying organic substances on a practical scale, the present invention is to pre-heat pyrolyze a gasification raw material that is easy to foam, foam once, then pulverize to adjust the particle size, and supply it to the gasification furnace Thus, a method is proposed in which continuous operation can be performed without causing operation trouble of the apparatus.

In addition, the gasification raw material as a whole is fused and grows into large-sized solid particles by pre-processing and pyrolyzing an organic material that is prone to foaming and an organic material that does not foam in advance. We propose a method that can prevent this.

When gasifying raw materials mainly composed of organic matter such as biomass (rice, bamboo, etc.), biomass such as wood, and organic waste (plastic, livestock excrement, construction waste wood, etc.) The gasification raw material is pretreated and thermally decomposed, and components that cause fusion due to the foaming phenomenon are decomposed in advance, and the generated pyrolyzed product is gasified. By this pretreatment, it is possible to separate in advance the softened / molten material generated during thermal decomposition, which could not be prevented by the conventional method, and to prevent mutual fusion of solid particles due to foamed material or the like. As a result, problems such as blockage and coking in the apparatus can be solved and gasification can be performed safely and continuously.

An embodiment of the present invention will be described below based on the example of FIG. In the pretreatment step, the gasified raw material 1 that has been subjected to the particle size adjustment, preliminary dehydration, drying, and the like is supplied into the pyrolysis furnace 3 through the nozzle 2. The heating of the gasification raw material 1 supplied to the inside of the pyrolysis furnace 3 can be performed by a method in which the heating gas 4 having a low oxygen concentration is brought into direct contact with the gasification raw material 1 or by the pyrolysis furnace 3 supplied with the gasification raw material 1. There is a method of heating the inner cylinder 5 indirectly from the outside. In the embodiment shown in FIG. 1, an example of a structure in which the heating gas 4 can be supplied to both the nozzle 7 disposed in the outer cylinder 6 of the pyrolysis furnace 3 and the nozzle 8 disposed in the inner cylinder is shown.

As the heating gas 4, combustion exhaust gas having a low oxygen concentration or water vapor is preferable. Although air may be used as the heating gas 4, it is not preferable because the low boiling point gas generated during the thermal decomposition may burn. An inert gas such as carbon dioxide or nitrogen may be used as the heating gas 4, but the processing cost increases.

In the case of organic substances excluding plastics, in general, in a temperature range of about 60 to 200 ° C., moisture evaporates and thermal decomposition of organic substances starts. In a material with a hemicellulose structure, this thermal decomposition begins, and the high-molecular component that is vulnerable to heat breaks down and becomes a low molecule. On the other hand, in the case of thermoplastics (polypropylene, polyethylene, polystyrene, vinyl chloride, etc.), softening / melting starts in a temperature range of about 150 to 250 ° C. Therefore, the supply temperature of the heating gas 4 for the gasification raw material is preferably 100 to 300 ° C. in consideration of heat dissipation. The appropriate temperature of the heating gas 4 is set in consideration of the type and amount of the gasification raw material, the heat radiation amount of the pyrolysis furnace 3 and the like. When the heating temperature is 300 ° C. or higher, the carbonization of the gasification raw material proceeds rapidly. When increasing the degree of carbonization, the temperature of the heating gas 4 may be set to a high temperature of 300 to 500 ° C.

The structure of the pyrolysis furnace 3 may be a horizontal rotary type such as a rotary kiln, but it softens and melts during pyrolysis among biomass such as rice plants and woods, and organic matter such as organic waste. Thus, a structure having a function capable of separating the fused solid particles with respect to the gasification raw material that causes mutual fusion of the solid particles is preferable. The embodiment of FIG. 1 shows a structural example of a horizontal cylindrical pyrolysis furnace in which a biaxial stirrer 9 is disposed inside a pyrolysis furnace inner cylinder 5. As the pyrolysis furnace 3, there is a case where a vertical cylinder type pyrolysis furnace is used.

When the pyrolysis furnace 3 having the structure shown in FIG. 1 is used, the gasification raw material 1 is supplied to the inner cylinder 5 of the pyrolysis furnace 3 through the nozzle 2 and then heated by the heating gas 4 to start pyrolysis. . When solid particles of the gasification raw material are fused in the process of pyrolysis, the fused state is broken by the stirrer 9 disposed in the inner cylinder 5 of the pyrolysis furnace 3 and separated into individual solid particles. Is done.

The thermal decomposition product which has undergone thermal decomposition after a predetermined residence time is discharged from the nozzle 10 and supplied to the gasifier. The heated gas 4 is discharged through the exhaust gas nozzle 11 disposed on the inner cylinder 5 or the exhaust gas nozzle 12 disposed on the outer cylinder 6.

In FIG. 2, the Example about the system using the gasification raw material after thermally decomposing with a thermal decomposition apparatus is shown. The gasified raw material (hereinafter referred to as carbide) that has been pyrolyzed in the pyrolysis step 13 is pulverized in the next pulverization step 14. As the carbide crusher, a vertical roll mill, a ball mill or the like is generally used.

The pulverized carbide is granulated to a particle size that is easy to transport in the granulation step 15. However, when the carbide utilization process is directly continuous with the pyrolysis process and the granulation is unnecessary, the granulation process 15 may be omitted.

The carbide granulated to an appropriate particle size by the granulation step 15 is transported to the pulverized coal boiler 17, the gasifier 18, the fuel processing step 19 and the like through the transporting step 16, and used.

As a heat supply medium necessary for pretreatment pyrolysis, heated solids (sand, limestone, catalyst, etc.) are supplied into the pyrolysis furnace instead of the aforementioned heating gas, and directly with the gasification raw material. You may heat by mixing. In this case, the heated solid material becomes a medium, and the gasification raw material is fused around the medium and may be naturally granulated to a particle diameter of several millimeters. In this case, the granulation operation becomes unnecessary.

The solid particles granulated by the above operation (gasification raw material subjected to thermal decomposition treatment) are used as a raw material for the gasification furnace in the next step. The type of the gasifier is not particularly limited, and there are a spouted bed type, a fluidized bed type, and a rotary kiln type, which can be used for any type.

The solid particles subjected to the pyrolysis treatment by the above-described method can be used as fuel for pulverized coal boilers, incinerators, etc. in addition to gasification raw materials.

As described above, in the pyrolysis product produced by the pyrolysis operation, trait components causing fusion are volatilized and separated in the above pyrolysis process. Therefore, it is possible to prevent the solid particles of the pyrolysis product from being fused to each other as fuel for a gasification raw material, a pulverized coal boiler, an incinerator or the like in the next stage. As a result, the driving operation can be performed with high efficiency in various processes without causing a driving trouble.

By the processing method shown in FIG. 1 according to the present invention, the pyrolysis operation was performed under the following conditions.
(1) Thermal decomposition conditions 1) Gasification raw material
Bamboo, particle size 6mm or less, 25kg / h
2) Thermal decomposition temperature
Average temperature of pyrolysis furnace inner cylinder 150-155 ° C
3) Pyrolysis device
Horizontal cylinder with a biaxial stirrer shown in FIG.
a) When the stirrer is not rotated Bamboo particles were fused to each other, and solid particles grown to a particle size of about 20 to 40 mm were obtained.
b) When the stirrer is rotated Since the fused solid particles are crushed by the stirrer, solid particles having a particle diameter of 6 mm or more were not generated.
(3) Gasification operation result The gasification operation was performed by the gasification system shown in FIG. 2 using the solid particles produced by the pyrolysis furnace shown in FIG. As a result, stable operation could be continued.
1) Gasification furnace A spouted bed type gasification furnace was used.
Gasification raw material supply rate 20kg / h
Gasification temperature 855 ℃
2) Product gas a) Gas composition
H ₂ 45, CO 26, CO ₂ 14, CH ₄ 7, and other 8 (vol.%)
b) Generated gas amount
50 Nm ³ / h

By the processing method shown in FIG. 1 according to the present invention, the pyrolysis operation was performed under the following conditions.
(1) Thermal decomposition conditions 1) Gasification raw material
Bamboo, particle size 6mm or less, 15kg / h
Thinned wood, particle size 6mm or less, 10kg / h
2) Thermal decomposition temperature
Average temperature of pyrolysis furnace inner cylinder 150-155 ° C
3) Pyrolysis device
Horizontal cylinder with biaxial agitator shown in Fig. 1 (2) Pyrolysis operation results
Fused solid particles were hardly generated, and solid particles having a particle size of 6 mm or less were obtained. .
(3) Gasification operation results
A gasification operation was carried out by the gasification system shown in FIG. 2 using solid particles produced by the pyrolysis furnace shown in FIG. As a result, it was possible to produce a gas with a high calorific value by continuing stable operation.
1) Gasification furnace A spouted bed type gasification furnace was used.
Gasification raw material supply rate 20kg / h
Gasification temperature 860 ℃
2) Product gas a) Gas composition
H ₂ 44, CO 25, CO ₂ 16, CH ₄ 7, and other 8 (vol.%)
b) Generated gas amount
57 Nm ³ / h

It is an example which shows embodiment in this invention. It is a figure which shows the Example of the whole pyrolysis, gasification, and electric power generation system which shows this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Gasification raw material 2 ... Nozzle 3 ... Pyrolysis furnace 4 ... Heating gas 5 ... Pyrolysis furnace inner cylinder 6 ... Pyrolysis furnace outer cylinder 7 ... Nozzle 8 ... Nozzle 9 ... Stirrer 10 ... Nozzle 11 ... Exhaust gas nozzle 12 ... exhaust gas nozzle 13 ... pyrolysis process 14 ... grinding process 15 ... granulation process 16 ... transport process 17 ... pulverized coal boiler 18 ... gasifier 19 ... fuel processing process

Claims (13)

A method for treating an organic material, characterized in that a gasification raw material mainly comprising an organic material is subjected to pretreatment pyrolysis within a temperature range of 100 ° C to 400 ° C and then gasified at 400 ° C or higher. 2. The method for treating organic matter according to claim 1, wherein the gasification raw material mainly composed of organic matter is rice plants, woody biomass, or organic waste. 2. The method for treating organic matter according to claim 1, wherein the gasification raw material mainly comprising the organic matter is a mixture of biomass of rice plants and woody species. 2. The method for treating an organic material according to claim 1, wherein the gasification raw material mainly comprising the organic material is a mixture of woody biomass and plastic. The method for treating organic matter according to claim 1, wherein the gasification raw material mainly comprising organic matter is a mixture of herbaceous grasses and construction waste wood. The method for treating organic matter according to claim 1, wherein the gasification raw material mainly comprising organic matter is a mixture of plastic and construction waste wood. In claim 1, claim 2, claim 3, claim 4, claim 5 and claim 6, as a method of supplying heat necessary for pretreatment pyrolysis, the oxygen gas concentration is 10 vol. % Or less of a heated gas as a medium. In claim 1, claim 2, claim 3, claim 4, claim 5 and claim 6, as a method of supplying heat necessary for pretreatment pyrolysis, a heating gas not containing oxygen gas is supplied as a medium. A method for treating organic matter. In claim 1, claim 2, claim 3, claim 4, claim 5, claim 7, claim 8, in place of the heating gas that is a supply medium of heat necessary for pretreatment pyrolysis And a method for treating an organic material, wherein the heated solid is directly mixed with a gasification raw material. In claim 1, claim 2, claim 3, claim 4, claim 5, claim 7, claim 8, claim 9, indirect heating for supplying heat necessary for pretreatment pyrolysis A method for treating organic matter, characterized in that it is shared by In claim 1, claim 2, claim 3, claim 4, claim 5, claim 6, claim 8, claim 8, claim 9 and claim 10, solid particles are stirred during pretreatment pyrolysis. A method for treating organic matter, comprising using a thermal decomposition apparatus having a function. In claim 1, claim 2, claim 3, claim 4, claim 5, claim 6, claim 7, claim 8, claim 9, claim 11, and claim 11, the thermal decomposition of the pretreatment The organic substance treated in the process is pulverized in the pulverization process, granulated to an appropriate particle size in the next granulation process, and then the granulated solid particles are used as a raw material for the gasifier. Processing method. In claim 1, claim 2, claim 3, claim 4, claim 5, claim 6, claim 7, claim 8, claim 9, claim 11, and claim 11, the thermal decomposition of the pretreatment The organic material treated in the process is pulverized in the pulverization process, granulated to an appropriate particle size in the next granulation process, and then the granulated solid particles are used as fuel for pulverized coal boilers, incinerators, etc. And a method for treating organic matter.

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