JP2002267136A - Method for gasifying and melting waste and its facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for gasifying and melting a waste capable of retaining re-scattering to a slight amount even when a dropping ash is charged in a gasifying melting furnace and avoiding a problem point brought about when a solidifying material is added to the ash to a solid matter and its facility. SOLUTION: The method for gasifying and melting the waste comprises the steps of thermally decomposing the waste, gasifying the waste, and melting its residue. The method further comprises the steps of pressure-molding the dropped ash recovered from a unit disposed between the gasifying melting furnace 10 and an exhaust gas dust collector 45 to a molding, and charging the molding in the melting furnace 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for gasifying and melting waste gas and a facility for carrying out the method.

[0002]

2. Description of the Related Art In recent years, a waste gasification and melting method has been developed in which waste such as municipal solid waste and shredder dust is pyrolyzed and gasified, burned to generate high-temperature gas, and the residue is melted and discharged. Is underway. This method has the great advantage that the heat of combustion can be recovered by gasifying the waste and the volume of final disposal can be reduced.

There are several methods for gasifying and melting waste, and one of them is a treatment method called a coke bed method. For example, in the method shown in FIG. 2, coke is charged into a gasification and melting furnace, deposited on the furnace bottom, and oxygen-enriched gas is blown to burn coke to form a high-temperature combustion zone. Waste, coke, and limestone are charged onto the high-temperature combustion zone, and the waste is pyrolyzed and gasified. The pyrolysis residue is melted into slag
It becomes metal and is discharged from the lower part of the furnace. The pyrolysis gas is burned in a secondary combustion furnace to become high-temperature exhaust gas, and is introduced into a heat recovery device such as a boiler to recover heat. The heat-recovered exhaust gas is introduced into a gas cooler, cooled, subjected to dust removal by a dust collector, and then emitted.

Until the gas generated in the gasification and melting furnace reaches the dust collector, relatively coarse particles of dust in the gas fall. For this reason, dust (hereinafter, referred to as fall ash) that has fallen into a device disposed between the gasification melting furnace and the dust collector is extracted. An operation is performed in which the extracted fallen ash is returned to the gasification and melting furnace to be melted and discharged as slag. The composition of the falling ash is shown in Table 1. Since it contains a large amount of SiO ₂ and CaO, it is melted in a gasification melting furnace to form slag.

[0005]

[Table 1]

When the fall ash is returned to the gasification and melting furnace, if the extracted fall ash is loaded into the melting furnace as it is, the fall ash will be scattered again. Solidification of falling ash is performed by adding a solidifying material such as cement or alkaline fly ash (fly ash collected by a dust collector when blowing slaked lime powder into exhaust gas to remove hydrogen chloride) and water. The kneading is performed by solidifying the kneaded material into granules or the like. However, this solidification method is a method utilizing the hydration reaction of cement and alkali fly ash, and until the solidified material has sufficient strength to the extent that it does not hinder charging into the gasification melting furnace, Since long-term curing is required, a curing storage facility is required. If a curing time cannot be provided, the kneaded material is introduced into a dryer and solidified.

[0007]

However, even if cement is added to the falling ash to form a solidified material, and this solidified material is charged into a gasification and melting furnace, it is easily broken and a large amount of re-scattering occurs. .

Further, when a solidified material such as cement is added to the fall ash to form a solidified material, a large amount of the solidified material must be added, so that the ratio of the re-scattered amount to the returned fall ash amount is high. Therefore, the effect of reducing the final disposal amount is reduced.

Further, it takes a long time until the solidified material has sufficient strength to such an extent that it does not hinder charging into the gasification and melting furnace. Storage tanks for solidified materials or indoor deposition sites must be provided.

If the curing time after kneading cannot be secured, a dryer must be installed.

[0011] The present invention solves the above-mentioned problems, so that even if falling ash is charged into a gasification and melting furnace, re-scattering is limited to a small amount, and a solidified material is added to the falling ash to add a solidified material. It is an object of the present invention to provide a waste gasification / melting method and a facility thereof capable of avoiding the problems that occur when the method is applied.

[0012]

According to a first aspect of the present invention, there is provided a waste gasification and melting method according to the first aspect of the present invention. The method for gasification and melting of a product is characterized in that fall ash collected from a device between a gasification and melting furnace and an exhaust gas dust collector is pressure-formed to form a compact, which is then charged into the gasification and melting furnace.

A waste gasification and melting method according to a second aspect of the present invention is characterized in that, in the first aspect of the present invention, only a fall ash is subjected to pressure molding to form a compact.

According to a third aspect of the present invention, there is provided the waste gasification / melting method according to the first or second aspect, wherein the fall ash is formed by another waste gasification / melting facility and / or waste. It is characterized by containing ash recovered from incineration equipment.

According to a fourth aspect of the present invention, there is provided a waste gasification / melting facility, comprising: a gasification / melting furnace for pyrolyzing waste to gasify and melting a residue; and a pyrolysis gas generated by the gasification / melting furnace. In a waste gasification and melting facility equipped with a secondary combustion furnace that burns gas, a heat recovery device that recovers heat of exhaust gas from the secondary combustion furnace, and a gas cooler that cools exhaust gas from the heat recovery device, A secondary combustion furnace, the heat recovery device, and a pressure forming device that converts the fall ash recovered from the gas cooler into a formed body, and a unit that loads the formed body into the waste gasification and melting furnace. It is characterized by.

According to a fifth aspect of the present invention, there is provided the waste gasification / melting facility according to the fourth aspect, wherein the ash collected from another waste gasification / melting facility and / or waste incineration facility is used. It has a receiving means.

According to a sixth aspect of the present invention, there is provided a waste gasification and melting facility according to the fourth or fifth aspect, wherein the pressure forming apparatus for converting fall ash into a solidified material includes a press forming machine. It is characterized in that it is.

The inventors of the present invention have found that when a granular solidified product of fall ash solidified by adding cement and water is charged into a gasification and melting furnace, the solidified product becomes an unexpectedly large amount of dust and re-scatters. We considered the problem to do.

The granular solidified fall ash is rapidly heated to a high temperature when charged into a high temperature gasification and melting furnace.
Due to the rapid rise in temperature, water (moisture) contained in the solidified material is gasified at once, so that the solidified material is destroyed to produce a powdery material, which is soared and scattered. it is conceivable that. In addition, the solidified material solidified with a solidifying material such as cement contains a large amount of water of hydration, and this water of hydration also gasifies in the same manner as moisture, so it is considered that powdery substances are generated and scattered. Can be

Therefore, in the present invention, in order to prevent the solidified product from being powdered due to the presence of water, only the fall ash is pressure-formed without adding water to form a molded body. The body is charged to a gasification and melting furnace.

It is preferable to use a press forming machine as a device for press-forming the fall ash.

When the fall ash is formed under pressure, usually, nothing is added and only the fall ash is formed under pressure. However, the melting point of the compact and the viscosity of the melt are adjusted. If necessary, a component adjuster such as lime powder or silica-containing substance powder may be added.

In the present invention, the fall ash to be formed into a compact and charged into the gasification and melting furnace is not limited to the one collected from the waste gasification and melting facility, but may be other waste gas. Fall ash collected from the chemical melting facility or incineration ash, fall ash or dust ash collected from other waste incineration facilities may be used. In addition, a mixture of falling ash collected from the waste gasification and melting furnace with fallen ash, incineration ash and dust collection ash collected from other waste gasification and melting facilities and other waste incineration facilities is formed. It may be charged into a gasification and melting furnace.

[0024]

FIG. 1 is a diagram showing an example of an embodiment of a waste gasification and melting facility according to the present invention. Reference numeral 10 denotes a gasification and melting furnace, which is formed in a vertical, cylindrical shape, and has an upper portion whose diameter is enlarged. 11 is a waste loading port, 1
Reference numeral 2 denotes a loading port for a compact obtained by press-molding fall ash, and 13 denotes a loading port for coke and limestone as auxiliary materials.

The gasification and melting furnace 10 forms a high-temperature combustion zone by depositing coke on the bottom of the furnace and blowing oxygen-enriched air into the coke layer to burn it. Is injected and thermally decomposed to melt the residue. The enlarged portion at the upper portion is the free board portion 14. Reference numeral 15 denotes a melting furnace gas outlet, and reference numeral 16 denotes a discharge port of the molten slag.

A main tuyere 17 for injecting air for burning coke or oxygen-enriched air is provided at a position where a high-temperature combustion zone is formed at the lower part of the melting furnace. Is provided with a sub tuyere 18 for blowing air for fluidizing the inputted waste. Further, the free board section 14 is provided with a three-stage tuyere 19 for blowing air for partially burning the pyrolysis gas (combustible gas) generated in the lower part of the furnace.

Reference numeral 40 denotes a secondary combustion furnace for burning the combustible gas discharged from the gasification and melting furnace 10; 42, a boiler as a heat recovery device; 43, an economizer as a heat recovery device;
Reference numeral 4 denotes a cooling tower which is a gas cooler for cooling the heat-recovered exhaust gas to a temperature suitable for purifying the exhaust gas, and reference numeral 45 denotes a bag filter.

Reference numeral 50 denotes the secondary combustion furnace 40 and the boiler 4
2. A tank for storing the fall ash extracted from the economizer 43 and the cooling tower 44. A facility for receiving fall ash and the like collected from other waste gasification and melting facilities or waste incineration facilities may be provided. Reference numeral 51 denotes a pressure molding device provided with a press molding machine. Reference numeral 52 denotes a receiving hopper for receiving the molded product of the fall ash, and reference numeral 53 denotes a transfer device for sending the molded product to the inlet 12 of the gasification and melting furnace.

The pressure forming apparatus 51 has a fall ash storage hopper, a fall ash input machine, a press forming machine, and a formed body removing machine. A release agent application machine may be provided in the pressure molding device 51, and the release agent may be applied from the inner surface of the mold of the molding machine so as to promote removal of the molded body.

The above press molding machine is for charging fall ash into a mold, pressing and molding, and then removing the mold to form a molded body. Even if the amount charged into the container changes, it is pressed with a predetermined pressure, so that there is an advantage that a material having a constant breaking strength can be obtained.

The molded body should be formed into a shape and dimensions suitable for allowing air or oxygen-enriched air to flow smoothly from the main tuyere when staying and melting in the high-temperature combustion zone described later. preferable. Further, the molding pressure at the time of press-molding the fall ash is set so as to have such a density that the molded body is strong enough not to be easily broken when the molded body is charged into a gasification melting furnace.

Since the fall ash is formed into a compact by press-forming without adding water or cement, the compact does not contain moisture, and even if it is heated to a high temperature in a gas melting furnace, the moisture is reduced. No destruction of the compact by gasification occurs. For this reason, the compact is not scattered in powder form.

The gasification and melting of the waste in the waste gasification and melting furnace having the above construction is performed as follows. Wastes such as municipal solid waste, industrial wastes or waste incineration residues, coke, limestone, and fallen ash compacts are respectively weighed and put into the gasification and melting furnace 10. Gasification and melting furnace 1
Among those charged to 0, coke is deposited on the furnace bottom, and hot air of air or oxygen-enriched air is blown into the main tuyere 17 there. Coke is burned by the blowing of the air or the oxygen-enriched air to form a high-temperature combustion zone. The injected waste stays while flowing by the air blown from the sub tuyere 18 above the high temperature combustion zone to form a fluidized bed. The waste is preheated while it is fluidizing,
Generates flammable gas upon thermal decomposition.

The compact formed from the pyrolysis residue of waste and the fall ash is melted in a high-temperature combustion zone, and is extracted from a molten slag discharge port 16 at the bottom of the furnace. On the other hand, the flammable gas generated by the thermal decomposition of the waste is partially burned by blowing air from the three-stage tuyere 19 in the free board part 14 and discharged from the melting furnace gas outlet 15.

The gas discharged from the gasification and melting furnace 10 is as follows:
After the secondary air is blown from the air blowing nozzle 41 in the secondary combustion furnace 40 and burned, it is sent to the boiler 42 and the economizer 43 to be recovered. The heat-recovered exhaust gas is sprayed with water in a cooling tower 44 and cooled to about 200 ° C. or less. Next, a harmful substance remover such as slaked lime powder for removing hydrogen chloride or activated carbon for adsorbing and removing dioxins is blown into the exhaust gas.
It is sent to 5 for dust collection processing.

Since the fall ash falls before the gas discharged from the gasification and melting furnace 10 reaches the bag filter 45, the secondary combustion furnace 40, the boiler 42, the economizer 4
3 and the falling ash is withdrawn from the cooling tower 44 and stored in a storage tank 50.
To be stored. The fall ash is formed into a compact by a press molding machine of a pressure molding device 51, and the compact is conveyed by a belt conveyor or the like and charged into the gasification and melting furnace 10.

Next, in the operation of the equipment whose basic configuration is the same as that of FIG. 1, the fall ash recovered from the secondary combustion furnace, the boiler, and the cooling tower is formed into a compact and charged into the gasification and melting furnace. The results of the test will be described. (Example 1) The collected fall ash was press-formed by a press forming machine to form a formed body having a diameter of 50 mm and a height of 50 mm, and was charged into a gasification melting furnace together with municipal waste and auxiliary materials. In this test, the molding pressure was set to 50 kg / cm ^{2 to} 20 kg / cm ^2.
The molded body was molded in four stages of 0 kg / cm ^{2, and} the amount of dust scattered when the molded body molded at each molding pressure was charged into a gasification melting furnace was examined.

Table 2 shows the results. The re-scattering rate described in Table 2 is a value obtained as follows. When the average amount of fall ash collected when the operation of returning fall ash to a molded body and returning it to the gasification melting furnace was not performed was investigated from long-term operation results, and the average collected amount and the molded body were charged The difference (increase) from the amount of fall ash collected was defined as the amount of re-scattered ash. Then, the ratio of the re-scattered amount to the charged amount of the falling ash compact was defined as the re-scattered ratio.

According to the results, the molding pressure was 50 kg / cm ²
In the case where the compact formed in the above manner was charged, the amount of dust re-scattered was large, and the effect obtained by forming the fall ash into the compact was small. However, the molding pressure is 100kg
/ Cm ² , the amount of re-scattered dust was reduced, and the effect of press-molding fall ash was clearly observed. Also, if the molding pressure is 200
In the case where a molded body molded at kg / cm ² was charged, the re-scattering rate was reduced to 6.7%.

Here, the molded body was formed into a cylindrical shape. However, the present invention is not limited to this, and is suitable for press molding and has dimensions and sizes that do not prevent blow-by of air or the like in a gasification and melting furnace. If the shape is a disk, a rectangular parallelepiped, a cube,
Other shapes may be used.

[0041]

[Table 2]

Comparative Example 1 Fall ash was solidified with cement and charged into a gasification and melting furnace. In this solidification treatment, 30 kg of fall ash, 20 kg of cement, and 50 kg of water were kneaded, dried by a dryer and solidified to obtain an amorphous solid. Then, the solidified product was charged into a gasification and melting furnace, and the scattering amount of dust at that time was examined. The re-scattering rate at this time was as follows. Re-dispersion rate with respect to the amount of solids charged: 36% Re-scattering rate with respect to falling ash in solids: 83% According to this result, since the charged solids contain a large amount of cement, they are scattered. As the amount increased, the re-dispersion rate became very large, and the effect of reducing the scattering of dust by making the fall ash into a solid was small.

[0043]

According to the present invention, the fall ash is formed into a compact by press-forming, and the compact is charged into a gasification and melting furnace. Only a small amount reduces final disposal after waste disposal.

Further, when the falling ash to be charged into the gasification and melting furnace is formed into a compact, it is not necessary to add a solidifying material such as cement, so that the final disposal amount does not increase due to the addition of the solidifying material.

Further, since the molded body can be obtained only by press-molding the fall ash, it is not necessary to secure a curing time until the strength of the molded body is developed, and it is necessary to provide a facility for storing the solidified material. Absent. Alternatively, there is no need to provide a dryer for developing the strength of the molded body in a short time.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an embodiment of a waste gasification and melting facility of the present invention.

FIG. 2 is an explanatory view of a conventional waste gasification and melting facility.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 Gasification and melting furnace 11 Waste loading port 12 Loading port for compacts formed by press-forming fall ash 13 Loading port for coke and limestone 14 Freeboard section 15 Melting furnace gas outlet 16 Discharge port for molten slag 17 Main tuyere 18 Secondary tuyere 19 Three-stage tuyere 40 Secondary combustion furnace 42 Boiler 43 Economizer 44 Cooling tower 45 Bag filter 50 Falling ash storage tank 51 Pressure forming device 52 Mold receiving hopper 53 Conveyor

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F27D 17/00 101 F27D 17/00 101Z 104 104D 105 105Z (72) Inventor Masahiro Matsuura 1-1-1, Marunouchi, Chiyoda-ku, Tokyo No. 2 Inside Nippon Kokan Co., Ltd. (72) Nao Nakamura, Inventor 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Yasuo Suzuki 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan Within Nihon Kokan Co., Ltd. (72) Inventor Hajime Akiyama 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Toshihiro 1-2-1 Marunouchi, 1-2 Chinoda-ku, Tokyo Japan (72) Inventor Tsuneo Matsudaira Tsuneo Matsudaira 1-2-1, Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 3K061 AA16 AB02 AB03 AC01 BA01 FA10 NB03 NB07 3K078 AA01 BA02 BA21 CA02 CA21 CA24 4K056 AA05 BA01 BB01 CA20 DA02 DA13 DB13 DB29 4K063 AA04 AA13 BA13 CA02 CA06 HA61

Claims (6)

[Claims] 1. A waste gasification / melting method for pyrolyzing waste to gasify and melting a residue, and press-forming and forming fall ash collected from a device between a gasification melting furnace and an exhaust gas dust collector. A method for gasification and melting of wastes, which comprises charging into a gasification and melting furnace. 2. The method for gasifying and melting waste according to claim 1, wherein only the fall ash is formed into a compact by pressure molding. 3. The waste gas according to claim 1, wherein the fall ash contains ash collected from another waste gasification and melting facility and / or waste incineration facility. Chemical melting method. 4. A gasification and melting furnace for pyrolyzing waste to gasify and melt the residue, a secondary combustion furnace for burning pyrolysis gas generated in the gasification and melting furnace, and a secondary combustion furnace. In a waste gasification and melting facility equipped with a heat recovery device that recovers heat of exhaust gas and a gas cooler that cools exhaust gas from the heat recovery device, the secondary combustion furnace, the heat recovery device, and the gas cooler Waste gasification and melting equipment, comprising: a pressure forming apparatus for converting fall ash collected from a wastewater into a formed body; and means for charging the formed body into the waste gasification and melting furnace. 5. The waste gasification and melting equipment according to claim 4, further comprising means for receiving ash recovered from another waste gasification and melting equipment and / or waste incineration equipment. 6. The waste gasification and melting equipment according to claim 4, wherein the press forming apparatus for converting the fall ash into a formed body is provided with a press forming machine.