JPH09111244A - Operation of waste melting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently operate at a low cost a waste melting furnace without decreasing coke combustion efficiency even in the case of fine granular coke along with avoiding blow-through phenomena, by setting up the tuyeres of the furnace in tiers in their height direction and changing the air blast ratios for the respective tuyeres according to coke granular size. SOLUTION: The tuyeres of a waste melting furnace A are set up in tiers in their height direction so as to treat wastes; for example, an air blasting is conducted through a primary tuyere and a second tuyere situated at a coke bed height in the furnace A differing in height from the primary tuyere according as choke granular size or a third tuyere at a height the closest to the choke bed height, thereby the air blast ratios for the respective tuyeres are changed according to coke granular size to operate the furnace A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of operating a melting furnace for thermally decomposing and melting municipal solid waste and various industrial wastes, and more particularly to an operation method capable of constant coke ratio operation regardless of coke particle size. .

[0002]

2. Description of the Related Art As a melting type cracking furnace for thermally melting waste by each process of drying, thermal decomposition and combustion melting, for example, Japanese Patent Publication No. 52-24790 and Japanese Patent Publication No. 60-1176.
No. 6 is disclosed. The former is to inject a gas containing 40% or more of oxygen into the waste to recover the generated gas, the molten slag and the molten metal. The latter is mainly solid waste with a water content of 50% or more.
50 ton per ton of waste by air and high-concentration oxygen in order to decompose into molten slag at ~ 1550 ° C and combustible gas
~ 300 Nm ³ of oxygen was applied to the lower tuyeres of the furnace bottom and above it 30
It has a furnace structure in which it is supplied from the upper tuyeres installed at a position of 0 to 1500 mm.

The amount of gas blown from the upper tuyeres is smaller than the gas fed from the lower tuyeres in both the amount of gas and the total amount of oxygen contained therein, and only the air is fed from the upper tuyeres to dry the waste. And enrich the air with high-concentration oxygen from the lower tuyeres to an oxygen concentration of 25-40%,
The high temperature combustion melts the incombustibles in the waste.

[0004]

In the conventional melting furnace operation, the latter having the upper tuyeres and the lower tuyeres (Japanese Patent Publication No. 60-
In the case of No. 11766), the amount of gas blown from the upper tuyeres and the total amount of oxygen contained therein are included in the total amount of gas blown from the upper tuyeres and lower tuyeres, and the amount thereof. It was necessary to set it to less than 50% of the total oxygen content.

This is because, when the amount of gas from the upper tuyeres and the total amount of oxygen are 50% or more of the total, heat exchange from the pyrolysis residue combustion zone to the dry distillation pyrolysis zone in the upper layer is carried out at high temperature. This is because a blow-through phenomenon is likely to occur at the top of the furnace without doing so.

This tendency is the same when the amount of combustion gas generated in the tuyere is excessive in the furnace structure having only the lower tuyeres. When this blow-through occurs, the high-temperature combustion gas generated by the combustion of coke and pyrolysis residue (char) in the lower part of the furnace with oxygen-enriched air flows away to the top of the furnace all at once, so the heat exchange rate inside the furnace is significantly reduced. Will be invited.

On the other hand, normally, air at room temperature is blown from the upper tuyeres, and the amount of the room temperature air is equal to or more than the amount of gas blown from the lower tuyeres in terms of gas amount and total oxygen amount contained therein. As a result, the combustion of the combustible residue after the thermal decomposition of the wastes present in the dry distillation pyrolysis zone can be promoted. From this point of view, increasing the blowing amount from the upper tuyeres improves the combustion efficiency of the pyrolysis residue in the furnace, that is, the utilization rate of the thermal energy of waste in the furnace. .

However, the blow-through mentioned above is likely to occur in such an operation, and before the thermal energy of the waste is used, there is a possibility that the utilization rate may be lowered due to the adverse effect of the blow-through. is there.

In the operation of the waste melting furnace, normally, coke for casting having a grain size of about 100 to 150 mm is used. However, since coke for casting is expensive, if coke having a smaller particle size than that is used in order to reduce the fuel cost, the combustion efficiency of the coke is reduced, resulting in a large amount of gas generation. In addition to that, the amount of heat of fusion also decreases, so stable operation becomes difficult unless the amount of air blown from the upper tuyeres is increased to direct the operation to secure thermal energy.

However, such an operation is liable to cause harmful effects due to blow-through, etc., and stable operation for a long time is difficult. Problem to be solved in the present invention, even when using a coke of a smaller grain size than the coke for casting,
It is to enable efficient operation without reducing the combustion efficiency of coke and avoiding the blow-through phenomenon.

[0011]

A method for operating a waste melting furnace according to the present invention is a method for operating a melting furnace when treating waste in a waste melting furnace having a multi-stage tuyere. It is characterized by arranging in multiple stages in the direction and changing the air blowing ratio of each tuyere according to the coke grain size.

Specifically, for example, when the coke to be used is changed from foundry coke to coke having a smaller grain size, a coke bed in a melting furnace which differs depending on the primary tuyere and the coke grain size. The air blowing rate of each tuyere can be changed according to the coke particle size by a method of blowing air from two tuyere positions, that is, the tuyere located at the height or the tuyere closest to the height.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Coke and pyrolysis residue in a furnace are burned by air at room temperature supplied from a blast tuyere and / or high-concentration oxygen to generate a gas, which rises toward the top of the furnace. Meanwhile, the packing is dried and pyrolyzed. When a coke particle size change test was conducted under the same blowing ratio of tuyeres arranged in multiple stages in the height direction of the melting furnace, as shown in Fig. 1, as the coke particle size became smaller, the combustion efficiency increased. Tends to decrease, and the gas generation amount tends to increase. this is,
This is because the solution loss reaction rate (C + CO ₂ = 2CO) increases as the coke becomes smaller.

Since the solution loss reaction is an endothermic reaction and lowers the meltability of the waste residue in the lower part of the furnace, the solution loss reaction is suppressed as much as possible in the coke existing region (hereinafter referred to as the coke bed layer) in the lower part of the furnace. It is preferable that the height of the coke bed is set to a position where the combustion efficiency of the coke is maximized.

When the coke particle size and the state of the combustion reaction and the solution loss reaction are examined under a constant gas flow rate by using an off-line test apparatus, as shown in FIG. It becomes closer to the primary tuyere as it becomes smaller.

The maximum burning position of coke has a particle size of 150.
5 mm above primary tuyere when mm coke for foundry is used
It was found that when the blast furnace coke having a particle size of 40 mm was used at a position of 0 to 80 cm, the position was 30 to 40 cm above the primary tuyere. That is, it means that the combustion heat of the coke can be maximized by setting the height of the coke bed to the above position.

Therefore, in the process of melting the waste residue, it is considered useful to change the height of the coke bed depending on the particle size of the coke used. On the other hand, as a method of promoting the combustion of waste residues and suppressing the solution loss reaction while effectively utilizing the combustion heat of coke,
It is desirable to set the secondary air blowing position at the upper end of the coke bed, that is, the melting position of the waste residue.

This is because when the combustion of the waste residue is promoted by the secondary air blowing, the heat of combustion can promote the melting of the waste residue. Therefore, as a method of setting the secondary air blowing position at the upper end of the coke bed, the inventors invented a method of installing tuyeres in multiple stages at intervals of 40 cm in the height direction of the melting furnace and changing the air blowing tuyere to be used depending on the coke particle size. .

For example, when the coke for casting is used, since the height of the coke bed is 80 cm above the primary tuyere, the tertiary tuyere located 80 cm above the primary tuyere and the primary tuyere. Use and. When a coke having a grain size of about 40 mm is used, a primary tuyere and a secondary tuyere 40 cm above the primary tuyere are used in the same way. In this way, by adjusting the air blowing ratio of each tuyere arranged in multiple stages in the height direction of the melting furnace according to the coke particle size, it is aimed at an operation that suppresses the increase in gas amount without changing the reaction efficiency. it can.

[0020]

[Examples] Table 1 shows an operation example in which the coke grain size of 150 mm was used, and the coke grain size was reduced, and the blast furnace coke was changed to continue the operation. Compared with the finer coke grain size, the operation data when the air blowing ratio of the multi-stage tuyere was changed (Example) and the operation data when the air blowing ratio was not changed (Comparative Example) were compared. It was confirmed that the operation when the ratio was changed was more stable and the increase in the coke ratio could be suppressed, and the operation method of the present invention was useful.

[0021]

[Table 1]

[0022]

INDUSTRIAL APPLICABILITY In melting and treating waste, it becomes possible to use fine grain coke having a low unit price, which is of great industrial value.

[Brief description of the drawings]

FIG. 1 is a chart showing the relationship between the coke particle size used and the combustion efficiency at the furnace top of a melting furnace.

FIG. 2 is a chart showing the relationship between the coke grain size used and the gas utilization rate in the furnace height direction.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location F23G 5/00 115 F23G 5/24 ZABB 5/027 ZAB B09B 3/00 ZAB 5/24 ZAB 303K

Claims (2)

[Claims] 1. A method of operating a melting furnace for treating waste in a waste melting furnace having a multi-stage tuyere, wherein the tuyere is arranged in multiple stages in a height direction, and the tuyere of each tuyere is arranged according to a coke particle size. A method for operating a waste melting furnace, which is characterized by changing a blowing ratio. 2. Blowers are blown from two locations, a primary tuyere and a tuyere located at a coke bed height in the melting furnace that differs depending on the coke particle size, or a tuyere closest to the height. The method for operating a waste melting furnace according to claim 1, wherein the air blowing ratio of each tuyere is changed according to the coke particle size.