JPH0688083A - Production of solid fuel from combustible waste - Google Patents

Abstract

PURPOSE:To facilitates the production of a pollution-free solid fuel in a short time from a combustible waste which is burned in a boiler and a combustion furnace. CONSTITUTION:A combustible waste is mixed by stirring with either an aqueous slurry of at least one calcium compound selected from among slaked lime, quick lime, and limestone having a particle diameter of 10mum to 1mm or the calcium compound and water. The obtained mixture is compression molded to produce a solid fuel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a solid fuel from combustible waste that is burned in a boiler and an incinerator,
In particular, it relates to a method for producing a solid fuel that can be advantageously applied to a combustible material containing chlorine.

[0002]

2. Description of the Related Art At present, municipal waste is incinerated as it is or disposed of in landfill. From the viewpoint of protecting the global environment, efficient use of waste incineration power generation and recycling of waste are required, and at the same time, strengthening pollution control and solving location problems are desired. Therefore, technologies for producing waste pretreatment fuel have begun to be studied. That is, as shown in FIG. 4, household waste 1 is crushed / sorted in step 3 and finely crushed waste 4 containing water after removing scraps / metals is mixed with CaO 2 and mixed / reacted. A step of mixing and reacting in step 5 to biologically stabilize the finely ground waste 4, and then crushing to extrude internal water in step 6, and a solid fuel 8 is produced in drying / neutralizing step 7. Is.

[0003]

[Problems to be Solved by the Invention] About 20 pieces of finely crushed waste
The water content is up to 45%, and when CaO is added to the water, the temperature rises to 20 to 70 ° C. due to the hydrothermal reaction. CaO + H ₂ O → Ca (OH) ₂ + 15.1kcal /
Therefore, food wastes were biologically stable and had the effects of denitrification and non-rotation, but the reaction time was long and practical because of the direct mixing method of waste and CaO as shown in the above formula. There was a problem not. That is, the combustible waste contains about 20 to 45% of water, but if CaO is directly mixed with the combustible waste as in the conventional method, C
CaO only partially penetrates and reacts with CaO in the presence of water on the surface of the combustible waste, and does not easily penetrate into the pores of the combustible waste. Therefore, there is a problem that it is difficult to uniformly disperse CaO in combustible waste, the reaction time becomes long, and the reaction rate is low.

In view of the above-mentioned state of the art, the present invention allows Ca compounds, including CaO, to permeate into combustible waste materials uniformly in a short time.
An object of the present invention is to provide a method capable of producing a solid fuel from a combustible waste, which has a high utilization rate of the a compound and, as a result, has a low emission concentration of pollutants.

[0005]

According to the present invention, (1) an aqueous slurry of one or more Ca compounds selected from the group consisting of slaked lime, quick lime, and limestone having a particle size of 10 μm to 1 mm is added to combustible waste and stirred and mixed. And (2) a method for producing a solid fuel, characterized in that the obtained mixture is compression-molded, and (2) one or more Ca selected from the group consisting of slaked lime, quick lime, and limestone having a particle size of 10 μm to 1 mm. A method for producing a solid fuel, characterized in that the compound and water are added and mixed with stirring, and the resulting mixture is compression molded. (3) The Ca compound is 1 to 30% by weight relative to the combustible waste. The method for producing a solid fuel according to the above (1) or (2) is characterized in that

[0006] The combustible wastes to which the present invention is applied include combustible general wastes such as paper, kitchen waste, wood, bamboo, plastics and rubber, and combustible industrial wastes such as coal waste, waste oil and waste plastics. As expected.

[0007]

As shown in FIG. 1, the solid fuel according to the present invention, when the Ca compound is taken in by ion exchange, becomes Ca compound ultrafine particles of about 10 nm, and
When it is taken in by impregnation, it is uniformly dispersed in combustible waste as Ca compound fine particles of submicron size, and in the case of slurry mixing or heat melting mixing, it is uniformly dispersed in combustible waste as fine particles of Ca compound of several μm to several tens of μm. To do C
Highly efficient desalting can be performed by using the compound a.
Although the Ca compound itself, which is the solid fuel, is extremely fine ultrafine particles, the Ca compound is incorporated in the combustible waste, and when the solid fuel is introduced into the fluidized bed, the fluidized bed or the combustor, these It behaves inside and can perform highly efficient desalination.

The production of combustible waste can be carried out by two kinds of methods as shown in FIGS. (1) Slurry preparation and mixing method (see FIG. 2) This method is a method of preparing a slurry of a Ca compound, mixing it with a combustible waste, and optionally curing and then compressing and molding. In FIG. 2, the Ca compound 9 is put into the adjusting tank 11 together with water 10 to prepare a slurry. On the other hand, the combustible waste 17 is crushed by the crusher 12, introduced into the mixer 13 together with the slurry and mixed, and then optionally cured in the curing tank 14, molded by the compression / molding machine 15 and heated and dried in the drying chamber 16. To obtain the solid fuel N. When mixing flammable waste and slurry Ca compounds,
Particularly, in the case of a water-repellent combustible material such as plastics and rubber, it takes a curing time to impregnate the Ca compound. The curing time is also affected by the particle size of combustible waste after crushing with a crusher.

This slurry preparation and mixing method is applied to limestone, quick lime,
Although all Ca compounds such as slaked lime can be used, it is particularly preferable when quick lime or slaked lime is used. Phenomenonally, ion exchange and impregnation (except for limestone)
And slurry mixing occurs. Further, when the combustible waste contains a component that melts when heated, the combustible waste that is physically crushed causes the Ca compound to become fine particles when the Ca compound is introduced into the combustor. Heat-melt mixing takes place therein.

(2) Direct mixing method (see FIG. 3) This method is a method of directly mixing the Ca compound, combustible waste, and water, and optionally curing the mixture for production. Figure 3
In, the Ca compound 9 is directly put into the mixer 13 together with the water 10 and the combustible waste 7 crushed by the crusher 12, mixed, and then cured in the curing tank 15, molded by the compression molding machine 15, and dried in the drying chamber. Solid fuel N dried at 16
Is what you get.

In this direct mixing method, all Ca compounds such as limestone, quick lime and slaked lime can be used, but this method is preferable especially in the case of limestone. Phenomenologically, the same ion exchange and impregnation (except in the case of limestone) and slurry mixing as in (1) occur. When the combustible waste contains a component that melts during heating, as in (1), the combustible waste that is physically crushed in the pretreatment stage causes the Ca compound to be added to the combustor. Heat-melt mixing occurs in which the fine particles are incorporated into the combustible material as fine particles.

The above means can be widely applied to almost all chlorine-containing combustible substances such as coal scraps, papers, kitchen wastes, fibers, woods, bamboos, plastics, rubbers and other wastes.

The operation of the method for producing solid fuel is as follows.
It depends on which of the above two types and what the combustible waste is.

(1) Ion-exchange action By any mixing method such as slurry preparation mixing method or direct mixing method, a combustible material having an ion-exchange ability such as a carboxyl group, an acidic hydroxyl group, a sulfonic acid group (for example, coal dust, Flammable waste such as papers, kitchen waste, fibers, wood, bamboos, plastics, and rubbers) in the presence of water, Ca ions are ion-exchanged and taken into the combustibles. Even after heating, it exists as Ca compound ultrafine particles of about 10 μm. The activity of such ultrafine particles is remarkably high, the utilization rate of Ca is 100%, and the reaction rate is extremely high.

(2) Impregnation action [0015] When the Ca compound is added to the porous combustible waste in the presence of water by any mixing method of the Ca compound slurry preparation mixing method or the direct mixing method, the Ca compound is impregnated. It is taken up even inside the combustible waste. After heating, it exists as a submicron polycrystal, and the reaction activity is second only to the ion exchange action.

(3) Slurry mixing action When the Ca compound slurry is added to the combustible waste by the slurry preparation mixing method or the direct mixing method, the Ca compound becomes fine particles of several μm to several tens of μm after heating, and is contained in the combustible waste. Since it is dispersed, the reaction activity becomes large.

(4) Heat-melting and mixing action When combustible waste contains components that melt when heated, it is added to the combustor by either the slurry preparation mixing method or the direct mixing method. The combustible waste, which is physically crushed and melts when heated,
The Ca compound is heated, melted, mixed, and taken into the combustible waste as fine particles, so that the reaction activity is increased.

As described above, the Ca compound is incorporated into the combustible waste as fine particles by any of the above actions, so that the reaction activity is increased. In addition, since Ca-containing combustible waste particles themselves can be handled in the same manner as ordinary combustible waste particles, when they are put into a fluidized bed, a fluidized bed, or a combustor, sufficient residence time in the furnace can be secured. In addition, the problem associated with handling of Ca fine particles does not occur. The amount of slaked lime, quick lime, limestone or a mixture thereof added to combustible waste is generally preferably 1 to 30% by weight. Even if the amount of addition is increased more than this, the utilization efficiency decreases.

[0019]

EXAMPLES Examples will be described below. (Example 1) (Slurry preparation and mixing method) As combustible waste, industrial waste containing 2.7% by weight of chlorine and 1.4% by weight of sulfur (including coal cinder, waste plastic, rubber, etc.) was used. The slaked lime after passing through a 325-mesh sieve is supplied to a preparation tank holding hot water at 90 ° C to obtain slaked lime slurry. After forming into a predetermined shape, it was heated and dried to obtain a solid fuel. 90 ° C. warm water was used to increase the reaction rate. This solid fuel was supplied to a circulating fluidized tank boiler combustor and burned.

○ (Slurry mixing condition) Chlorine-containing combustible waste: 80 kg Slaked lime: 5 kg (Average particle size:
40 μm) Water: 10 kg Slaked lime slurry / combustible waste: 19% ○ (compression molding conditions) Pressure: 3.1 kg / cm ² Heating temperature: 87 ° C. Solid fuel average diameter: 3 mm ○ (circulating fluidized tank boiler) Combustion temperature As a result of analysis of exhaust gas and residues of a combustion furnace at 850 ° C., the desalination rate was 37.
%Met.

Example 2 (Slurry Preparation and Mixing Method) Under the same conditions as in Example 1, slaked lime slurry and combustible waste were mixed in a mixer, and then held in a curing tank for 30 minutes, and then a compression molding apparatus. After being formed into a predetermined shape by heating, it was heated and dried to obtain a solid fuel. This solid fuel was supplied to a circulating fluidized tank boiler combustor and burned.

○ (Slurry mixing condition) Chlorine-containing combustible waste: 80 kg Slaked lime: 5 kg (average particle size:
40 μm) Water: 10 kg Slaked lime slurry / combustible waste: 19% ○ (curing condition) Curing time: 30 minutes Curing temperature: 43 ° C ○ (compression molding condition) Pressure: 3.1 kg / cm ² Heating temperature: 87 ° C Solid Average diameter of fuel: 2 mm ○ (circulating fluidized-bed boiler) Combustion temperature: 850 ° C. Analysis of exhaust gas and residues in the combustion furnace showed a desalination rate of 40
%Met.

(Example 3) (Direct mixing method) A slaked lime prepared in the same manner as in Example 1 was crushed with a crusher while adding a small amount of water, and a waste plastic (polyvinyl chloride, polyethylene, etc.) having heat melting property was contained. ) Containing industrial waste (containing 3.0% by weight of chlorine and 1.2% by weight of sulfur) in a mixer, molded into a predetermined shape by a compression molding device, and dried by heating to obtain a solid fuel. . this,
The solid fuel was supplied to a circulating fluidized tank boiler combustor and burned.

○ (Mixing condition) Combustible waste containing chlorine: 80 kg Slaked lime: 5 kg (Average particle size:
40 μm) Water: 3 kg Slaked lime slurry / combustible waste: 10% ○ (compression molding conditions) Pressure: 3.2 kg / cm ² Heating temperature: 85 ° C Average diameter of solid fuel: 3 mm ○ (circulating fluidized tank boiler) Combustion temperature : As a result of analysis of exhaust gas and residue of 850 ° C. combustion furnace, desalination rate is 35
%Met.

(Example 4) (Slurry preparation and mixing method) Quick lime was used instead of slaked lime in Example 1, and after mixing quick lime slurry and combustible waste with a mixer, further holding in a curing tank for 30 minutes After being molded into a predetermined shape by a compression molding device, it was heated and dried to obtain a solid fuel. This solid fuel was supplied to a circulating fluidized tank boiler combustor and burned.

○ (Slurry mixing conditions) Chlorine-containing combustibles: 80 kg Quick lime: 5 kg (Average particle size:
40 μm) Water: 10 kg Quick lime slurry / combustible waste: 20% ○ (curing condition) Curing time: 30 minutes Curing temperature: 45 ° C ○ (compression molding condition) Pressure: 3.01 kg / cm ² Heating temperature: 88 ° C Solid Average diameter of fuel: 2 mm ○ (circulating fluidized-bed boiler) Combustion temperature: 850 ° C. Analysis of exhaust gas and residues in the combustion furnace revealed a desalination rate of 37
%Met.

(Example 5) (Slurry preparation and mixing method) Limestone was used in place of slaked lime in Example 1, limestone slurry and combustible waste were mixed with a mixer, and further held in a curing tank for 30 minutes. After being molded into a predetermined shape by a compression molding device, it was heated and dried to obtain a solid fuel. This solid fuel was supplied to a circulating fluidized tank boiler combustor and burned.

○ (Slurry mixing condition) Chlorine-containing combustible waste: 80 kg Limestone: 5 kg (average particle size:
40 μm) Water: 10 kg Limestone slurry / combustible waste: 20% ○ (curing conditions) Curing time: 30 minutes Curing temperature: 45 ° C ○ (compression molding conditions) Pressure: 3.01 kg / cm ² Heating temperature: 88 ° C Solid Average diameter of fuel: 2 mm ○ (circulating fluidized-bed boiler) Combustion temperature: 850 ° C As a result of analysis of combustion furnace exhaust gas and residues, desalination rate is 35
%Met.

(Example 6) (Direct mixing method) Quick lime was crushed with a crusher while adding a small amount of water, and waste plastic (polyvinyl chloride;
After mixing industrial waste (containing polyethylene etc.) (containing 3.0% by weight of chlorine and 1.2% by weight of sulfur) with a mixer, it is molded into a predetermined shape by a compression molding device, dried by heating, and solidified. Used as fuel. This solid fuel was supplied to a circulating fluidized tank boiler combustor and burned.

○ (Mixing conditions) Chlorine-containing combustible waste: 80 kg Quick lime: 5 kg (Average particle size:
40 μm) Water: 10 kg quicklime slurry / combustible waste: 10% ○ (compression molding conditions) Pressure: 3.3 kg / cm ² Heating temperature: 86 ° C. Average diameter of solid fuel: 3 mm ○ (circulating fluidized tank boiler) Combustion temperature : Desalination rate is 33 at 850 ° C as a result of analysis of exhaust gas and residue of combustion furnace
%Met.

(Example 7) (Direct mixing method) Limestone was crushed with a crusher while adding a small amount of water, and waste plastic (polyvinyl chloride;
After mixing industrial waste (containing polyethylene etc.) (containing 3.0% by weight of chlorine and 1.2% by weight of sulfur) with a mixer, it is molded into a predetermined shape by a compression molding device, dried by heating, and solidified. Used as fuel. This solid fuel was supplied to a circulating fluidized tank boiler combustor and burned.

○ (Mixing condition) Chlorine-containing combustible waste: 80 kg Limestone: 6 kg (Average particle size:
40 μm) Water: 3 kg Limestone slurry / combustible waste: 11% ○ (compression molding conditions) Pressure: 3.5 kg / cm ² Heating temperature: 86 ° C Average diameter of solid fuel: 3 mm ○ (circulating fluidized tank boiler) Combustion temperature : As a result of analysis of exhaust gas and residue of 850 ° C combustion furnace, desalination rate is 31
%Met.

(Comparative Example 1) The same combustible waste as in Example 1 and limestone after passing through a 325-mesh sieve were mixed in a mixer, and then molded into a predetermined shape by a compression molding device.
It was heated and dried to obtain a solid fuel. This solid fuel was supplied to a circulating fluidized tank boiler combustor and burned.

○ (Mixing conditions) Chlorine-containing combustibles: 80 kg Limestone: 7 kg (Average particle size:
28 μm) Limestone / combustible waste: 21% ○ (compression molding conditions) Pressure: 128 kg / cm ² Heating temperature: 87 ° C Average diameter of solid fuel: 3 mm ○ (circulating fluidized tank boiler) Combustion temperature: 850 ° C of combustion furnace As a result of analysis of exhaust gas and residues, the desalination rate was 25.
%Met.

[0035]

According to the present invention, since the Ca compound is uniformly and rapidly dispersed in the combustible waste, when the solid fuel produced by the method of the present invention is finally burned in a boiler or an incinerator, chlorine is not used. , Harmful substances such as sulfur are CaO, Ca (OH) ₂
Alternatively, since CaCO ₃ reacts with high efficiency, it is possible to obtain an excellent non-polluting solid fuel with high utilization efficiency of Ca and low emission concentration of harmful substances such as HCl and SOx.
Further, even during compression molding, it is possible to mold at a pressure of several kg / cm ² or less, which makes it possible to downsize the manufacturing apparatus.

Further, the solid fuel produced by the method of the present invention has the following advantages. (1) In the conventional method of adding only the Ca compound to the dry combustible waste, the Ca compound is only physically mixed between the combustible particles, and depending on the combustion conditions for combustion in the boiler or the incinerator. The unreacted Ca compound is discharged to the outside of the boiler or the incinerator combustor, and the utilization efficiency of the Ca compound is reduced. On the other hand, in the method of the present invention, the Ca compound is partially ion-exchanged with the ion-exchange groups such as carboxyl group, acidic hydroxyl group, and sulfonic acid group in the combustible waste to strongly bond with the combustible particles. It is difficult to be discharged unreacted inside, the reaction rate is high and the reaction rate is extremely high.

(2) In the conventional method of adding particles of a Ca compound to a water-containing combustible waste, C which is not in an activated state is used.
Reaction is slow because it is a solid / solid reaction between a compound and combustible waste. On the other hand, in the present invention, by mixing a Ca compound with water, the Ca compound is partially ion-exchanged with an ion-exchange group such as a carboxyl group, an acidic hydroxyl group or a sulfonic acid group in the combustible waste to form a combustible substance. The reaction rate is extremely high because it is taken into the inside and becomes an activated state in which it easily reacts.

(3) In the conventional method of adding the Ca compound to the dry combustible waste, the water impregnated in the combustible waste particles flows out to the surface of the combustible material and then reacts with the Ca compound on the surface. Since the process of diffusing into the flammable material again occurs, the impregnation time is very long. On the other hand, in the present invention, since the Ca compound easily forms an aqueous solution with the water on the surface of the combustible waste and is quickly impregnated inside the combustible waste, the time required for impregnation is short and the curing time is long. Can be shortened.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a phenomenon and a reaction during burning of a solid fuel according to the present invention.

FIG. 2 is an explanatory view showing a manufacturing process of the solid fuel according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a manufacturing process of a solid fuel according to a second embodiment of the present invention.

FIG. 4 is an explanatory view showing a conventional solid fuel manufacturing process.

Front page continuation (72) Inventor Yasuyuki Takarada 3535-3, Hishimachi, Kiryu-shi, Gunma Prefecture (72) Inventor Toshio Haneda 2-5-1, Marunouchi, Chiyoda-ku, Tokyo Sanryo Heavy Industries Co., Ltd. (72) Inventor Naoyoshi Oda 2-5-1, Marunouchi, Chiyoda-ku, Tokyo Sanryo Heavy Industries Co., Ltd. (72) Inventor Shinai Koizumi 2-5-1 Marunouchi, Chiyoda-ku, Tokyo Sanryo Heavy Industries Co., Ltd. (72 ) Inventor Yukihisa Fujima 5-717-1, Fukahori-cho, Nagasaki-shi, Nagasaki Sanryo Heavy Industries Co., Ltd.Nagasaki Research Institute (72) Inventor Yoshiyuki Takeuchi 4-6-22 Kannon-shinmachi, Nishi-ku, Hiroshima-shi Mitsubishi Heavy Industries Hiroshima In the laboratory

Claims (3)

[Claims] 1. Burnable waste includes slaked lime, quick lime and 10 μm.
A method for producing a solid fuel, comprising adding an aqueous slurry of one or more Ca compounds selected from the group consisting of limestone having a particle diameter of m to 1 mm, stirring and mixing, and compression-molding the obtained mixture. 2. Burnable waste includes slaked lime, quick lime and 10 μm.
A method for producing a solid fuel, comprising adding one or more Ca compounds selected from the group consisting of limestone having a particle diameter of m to 1 mm and water, stirring and mixing the mixture, and compression-molding the obtained mixture. 3. The method for producing a solid fuel according to claim 1, wherein the weight ratio of the Ca compound to the combustible waste is 1 to 30% by weight.