JPH10227423A - Method for melting waste material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an operation expenditure without making a facility complicated. SOLUTION: In a method of melting waste material for supplying oxygen rich gas and auxiliary fuel into a reaction tower 1, igniting and melting the waste material, metallic fine pieces capable of being oxidized and ignited in a predetermined temperature range are supplied into the reaction tower 1 in addition to auxiliary fuel such as fossil fuel or the like in order to keep an inside part of the reaction tower 1 in a state in which ignited ash can be melted. With such an arrangement as above, it is possible to perform an efficient melting operation with a less amount of carrying energy, reduce substantially a feeding amount of auxiliary fuel, resulting in that it has a substantial effect in view of reducing operation expenditure. In particular, in the case that some fine metallic pieces are transported with oxygen rich gas and supplied into the reaction tower 1, it may be efficiently transported with a simple configuration and it is effective in view of saving facility expenditure and operation expenditure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waste incineration method for incinerating waste and melting the residue generated at this time.

[0002]

2. Description of the Related Art Generally, a large amount of residue (incinerated ash) generated during incineration of waste is disposed of in a landfill. In recent years, in order to reduce costs associated with landfill disposal,
Various melting techniques for melting and solidifying the residue to reduce the volume have been proposed and are being put to practical use.

[0003] In these melting techniques, since the self-combustion by air alone does not reach the melting temperature of the residue (1200 to 1500 ° C), a high temperature necessary for melting is obtained by various methods. Separately, incineration ash is heated to a high temperature with fossil fuel etc. to melt it by heating, incineration ash is heated to a high temperature using an electric arc, etc. Pyrolysis gas method in which gas components and residues (mainly carbon content) are separated and then recombusted and melted, or waste and combustibles (such as coke) are mixed with oxygen-enriched air or high-purity oxygen. There is a direct melting method in which combustion and melting are performed while obtaining a high temperature.

[0004]

However, fossil fuel supplied as an auxiliary fuel in the surface melting method or the direct melting method and electric power used in the electric melting method are major factors that increase the operating cost. Further, the PSA method and the cryogenic separation method for obtaining the oxygen-enriched gas used in the direct melting method also require a large amount of electric power, and there is a problem that the operating cost increases. On the other hand, in the pyrolysis gas method, the operation cost is reduced by effectively utilizing the pyrolysis gas, but the equipment is complicated and it is not always effective in reducing the cost.

[0005] In view of the above-mentioned problems in the prior art, a main object of the present invention is to provide a method for melting waste which can reduce the operating cost without complicating the equipment.

[0006]

SUMMARY OF THE INVENTION According to the present invention, there is provided, in accordance with the present invention, a method for melting waste, comprising supplying an oxygen-enriched gas and an auxiliary fuel into a reaction column to burn and melt the waste. The present invention is attained by providing a method for melting waste, comprising supplying metal fragments that can be oxidized and burned in a predetermined temperature range into the reaction tower.

In particular, it is preferable that the metal strip is transported in a gas stream to the oxygen-enriched gas and supplied into the reaction tower.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described in detail below based on embodiments shown in the accompanying drawings.

FIG. 1 shows a waste melting apparatus constructed based on a waste melting method according to the present invention. This waste melting apparatus 1 is provided with a reaction tower 2 for thermally decomposing, burning, and melting waste, a waste input section 3 provided at an upper portion of a side wall of the reaction tower 2, and a lower portion of a side wall of the reaction tower 2. Supply units 4 and 5 for the oxygen-enriched gas and the auxiliary fuel, a combustion gas extraction unit 6 provided on the top wall of the reaction tower 2, and a molten slag extraction unit 7 provided on the bottom wall of the reaction tower 2 And

[0010] The waste to be treated is introduced from the waste inlet 3 and filled into the reaction tower 2 at a predetermined height. When charging the waste into the reaction tower 2, it is desirable to carry out sorting and crushing to make the waste uniform.

The waste in the reaction tower 2 self-combustes with the oxygen-enriched gas introduced from the oxygen-enriched gas supply unit 4. If only the self-combustion with the oxygen-enriched gas alone is not performed, a high temperature enough to melt is not obtained and the ash accumulates at the bottom of the reaction tower 2 as incineration ash. Input from section 5. As a result, the lower portion of the reaction tower 2 is brought to a high temperature state sufficient for melting, and the incinerated ash is melted.

The combustion gas generated by the combustion of the waste rises while flowing through the gap between the waste filled in the reaction tower 2. At that time, the high-temperature combustion gas comes into contact with the waste, whereby the waste is dried and further thermally decomposed.
The waste is thermally decomposed at about 400 ° C. or higher to generate a decomposition gas. Waste is carbonized through pyrolysis.
Non-combustible materials such as glass and iron remain. Low melting point incombustibles such as aluminum dissolve. The cracked gas is guided to the outside of the reaction tower 2 from the combustion gas outlet 6 together with the combustion gas.

In this way, the packed bed of waste in the reaction tower 2 is roughly divided into five upper and lower layers according to each process of drying, pyrolysis, combustion and melting. That is, the drying zone A is located at the top, the pyrolysis zone B is located below, the combustion zone C is located below, and the oxygen-enriched gas and the auxiliary fuel supply units 4 and 5 are located below. And combustion and melting zone D
However, a molten metal pool E is formed at the bottom of the reaction tower 2 thereunder. The molten slag of the molten metal pool E flows out of the molten slag removal section 7 to the outside.

Meanwhile, metal aluminum powder is added to the oxygen-enriched gas blown into the reaction tower 2 from the oxygen-enriched gas supply section 4, and the aluminum-enriched gas is transported in a gas stream to the oxygen-enriched gas.
It is thrown in. At normal pressure, metallic aluminum self-combustes at 1300 ° C. or higher, depending on the oxygen partial pressure. Therefore, when the metal aluminum powder is charged into the reaction tower 2 maintained at a predetermined temperature (1300 to 1400 ° C. or higher) by the above-mentioned auxiliary fuel such as fossil fuel, the oxidation combustion reaction of the metal aluminum is rapidly caused. .

Metallic aluminum contains a large amount of energy, as can be seen from its production process, and emits a large amount of heat of reaction (calorific value of 7,500 kcal / kg) when oxidizing and burning. In addition, only aluminum oxide (alumina) is generated as a combustion product, and combustion gas such as that generated when fossil fuel is burned is not generated. For this reason, there is no take-out energy, and it is possible to use substantially all of the released reaction heat as the heat of fusion of the incinerated ash. Therefore, the high temperature (1350 to 1500 ° C.) required for melting can be obtained extremely efficiently, and the amount of auxiliary fuel such as fossil fuel can be significantly reduced.

Such a waste melting apparatus 1 includes, for example,
It is applied to a waste treatment plant as shown in FIG.

In this waste treatment plant, first, the waste in the carry-in waste pit 11a carried in from the transport truck is crushed by the crusher 12 into an appropriate size. The crushed waste is temporarily stored in the crushed garbage pit 11b, and then is appropriately conveyed to a crane and charged into the dust supply device 13. In the dust supply device 13, the crushed waste is molded and sequentially sent to the waste input section 3 of the waste melting device 1.

The auxiliary fuel supply unit 5 of the waste melting apparatus 1 is supplied with auxiliary fuel from an auxiliary fuel storage tank 14, and the oxygen-enriched gas supply unit 4 is supplied with oxygen-enriched gas from an oxygen generator 15. Supplied. This oxygen generator 15 is a PSA
(Pressure Swing Absorption) method is to remove a fixed amount or substantially the entire amount of nitrogen from air to obtain an oxygen-enriched gas. Metallic aluminum powder is added to the oxygen-enriched gas at appropriate locations.

The molten material recovered from the molten slag removal section 7 of the waste melting apparatus 1 is dropped into water in a slag cooling tank 16 and solidified into a glass. This granulated slag, once
After being stored in the slag pit 17, it is appropriately carried out of the yard.

The combustion gas containing the decomposed gas discharged from the combustion gas outlet 6 of the waste melting device 1 is supplied to the secondary combustion furnace 18.
And is burned using the auxiliary fuel supplied from the auxiliary fuel storage tank 14. The secondary combustion furnace 18 is supplied with the air in the sewage waste pit 11 sucked by the forced air blower 19, and the garbage pit 1 collected by the sewage pump 20.
The wastewater in 1 is injected and incinerated together with the combustion gas.

The combustion gas flowing through the secondary combustion furnace 18 is then sent to a waste heat boiler 21 for heat recovery. Here, the steam obtained by heat exchange with the combustion gas is supplied to the turbine 22.
To drive the generator 23. The power obtained at this time is supplied to on-site electrical equipment such as the oxygen generator 15.

The combustion gas that has passed through the waste heat boiler 21 and cooled down is sent to the multicyclone 24 where relatively large soot is collected, and then fine soot is collected by the electric precipitator 25. Thereafter, the air is released from the chimney 26 into the atmosphere.
The above combustion gas flow is generated by the induction blower 27.

The collected ash collected from the waste heat boiler 21, the multicyclone 24, and the electric dust collector 25 is returned to the crushed waste pit 11b, etc., and is processed again by the waste melting apparatus 1.

In the meantime, as shown in FIG. 3, the waste melting method according to the present invention involves incineration and melting while turning a waste piece in a room supplied with an oxygen-enriched gas and kept at a predetermined high temperature. The present invention can be applied to a waste melting apparatus 32 provided with a swirling incineration melting chamber 31 having a vertical cylindrical inner wall. Below the swirling incineration melting chamber 31 is a swirling incineration melting chamber 3.
A secondary melting chamber 33 having a rectangular box-shaped inner wall for retaining the melt descending from 1 is provided.

On the inner peripheral surface 31a of the swirling incineration melting chamber 31,
Gas outlets 34 to 39 are open facing the tangential direction of the circumference. A mixture of the circulating gas and the oxygen-enriched gas is ejected from these gas outlets 34 to 39 to generate a swirling flow over the entire area of the room. The circulating gas is obtained by circulating a part of the combustion gas once discharged from the incineration melting furnace 32 by a circulating blower (not shown).

A refuse transport pipe 40 is connected to the uppermost gas outlet 34, and waste pieces supplied from the refuse transport pipe 40 are conveyed by a gas mixture of an oxygen-enriched gas and a circulating gas and swirled. It is designed to be charged into the top of the incineration melting chamber 31.

A communication hole 41 provided at the lower end of the swirling incineration melting chamber 31 is open to the ceiling at one end of the secondary melting chamber 33. On the floor surface 33a on the other end side of the secondary melting chamber 33, a tap hole 42 for collecting a molten material is formed. In addition, a flue 43 for discharging combustion gas is opened on a side surface of the secondary melting chamber 33, and is connected to a heat recovery unit. A burner 44 is provided on the side of the tap hole 42.

Metal aluminum powder is added to the mixture of the circulating gas and the oxygen-enriched gas ejected from the gas outlets 34 to 39, and the reaction heat generated by the oxidizing combustion of the mixed gas causes the swirl incineration and melting chamber 31 to generate heat. It is kept at a predetermined high temperature state. At this time, if the amount of the metal aluminum powder is changed in the height direction of the room instead of uniformly charging the metal aluminum powder from the gas outlets 35 to 39, the temperature distribution suitable for combustion and melting can be efficiently performed. Can be formed.

The waste pieces supplied from the gas outlet 34 fall down in a spiral flow in the swirling incineration / melting chamber 31 and burn while falling spirally. It collides and adheres to the inner peripheral surface 31a. And
A sufficient residence time is given while flowing down the inner peripheral surface 31 a, most of which is melted, and drops on the floor surface 33 a of the secondary melting chamber 33 through the communication hole 41. The mixture of the molten material and the unmelted material sent to the secondary melting chamber 33 is given a sufficient residence time while gradually moving on the floor surface 33 a toward the tap hole 42, and is further subjected to a flame by the burner 44. Is heated to complete the melting, and is recovered from the tap hole 42.

In the above-described embodiment, metal aluminum powder is used for the metal strip. However, the component of the metal strip in the present invention is not limited to aluminum.
Although iron and magnesium can be applied, aluminum is preferred from the viewpoint of easy availability and calorific value. In addition, impurities-rich metals recovered as waste can be used, which saves operating costs. Further, the size of the metal flakes is desirably as small as possible and powdery from the viewpoint of ignitability, etc., but it is sufficient that the metal flakes are small enough to be oxidized and combustible in the reaction tower. For example, those which are crushed into small pieces can be similarly applied.

Among the collected waste products, for example, aluminum alloy materials such as aluminum die-cast products such as aluminum wheels and engine blocks are difficult to recycle by improving the purity by melting. Since such non-recyclable metal waste can be used, resources can be effectively used.

Further, in the above-described embodiment, the melting treatment of general waste in which combustibles and incombustibles are mixed has been described. However, the present invention is applicable to various kinds of sludge, for example, sludge discharged from a chemical production plant. It can be widely used for melting waste such as sewage sludge and construction sludge, or shredder dust, etc. It can be easily realized.

[0033]

As is apparent from the above description, according to the waste melting method of the present invention, the auxiliary fuel is used to keep the incineration ash at a high temperature (1350 to 1500 ° C.) at which the incineration ash can be melted. Supply metal strips in addition to
Since it is possible to perform efficient melting with a small amount of energy taken out, and to greatly reduce the amount of auxiliary fuel such as fossil fuel, it has a great effect in reducing operating costs. In particular, when the metal flakes are transported in a gas stream to the oxygen-enriched gas and supplied into the reaction tower, the metal flakes can be transported efficiently with a simple configuration, which is effective in reducing equipment costs and operation costs. is there.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a waste melting apparatus configured based on a waste melting method according to the present invention.

FIG. 2 is a block diagram schematically showing a waste treatment plant to which the waste melting apparatus shown in FIG. 1 is applied.

FIG. 3 is a schematic bird's-eye view showing another embodiment of the waste melting apparatus configured according to the present invention, which is divided by a vertical plane.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Waste melting apparatus 2 Reaction tower 3 Waste input part 4 Oxygen-enriched gas supply part 5 Auxiliary fuel supply part 6 Combustion gas extraction part 7 Molten slag extraction part 11 Garbage pit, 11a Import garbage pit, 11b
Crushed garbage pit 12 Crusher 13 Dust supply device 14 Auxiliary fuel storage tank 15 Oxygen generator 16 Slag cooling tank 17 Slag pit 18 Secondary combustion furnace 19 Push blower 20 Sewage pump 21 Waste heat boiler 22 Turbine 23 Generator 24 Multicyclone 25 Electricity Dust collector 26 Chimney 27 Induction blower 31 Revolving incineration melting chamber, 31a inner peripheral surface 32 Waste melting device 33 Secondary melting chamber, 33a Floor surface 34-39 Gas outlet 40 Waste transport pipe 41 Communication hole 42 Outlet 43 Smoke Road 44 Burner A Drying zone B Pyrolysis zone C Burning zone D Burning / melting zone E Molten pool

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI F23L 7/00 F23L 7/00 B

Claims (2)

[Claims] 1. A waste melting method in which an oxygen-enriched gas and an auxiliary fuel are supplied into a reaction tower to burn and melt the waste, wherein the metal strip capable of being oxidized and burned in a predetermined temperature range is formed. A method for melting waste, comprising feeding into a reaction tower. 2. The method for melting waste according to claim 1, wherein the metal strip is transported in a gas stream to the oxygen-enriched gas and supplied into the reaction tower.