JP2002357309A - Waste melting furnace and its operating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste melting furnace which is capable of continuing stable operation and decreased in a damage amount of a furnace wall and reduced in a using amount of coke. SOLUTION: The shaft type waste melting furnace is provided, in order, with a free board part 11; a sub-tuyere 22 which is connected to a part below the free board part 11 and through which oxygen-containing gas is blown in; a thermal decomposition part 13 where waste is accumulated and thermally decomposed; a main tuyere 21; and a melting part 15 to melt thermal decomposition residue of falling-down waste. A ratio (D3 /D2 ) of an inside diameter D3 of the melting part 15 to an inside diameter D2 of the thermal decomposition part 13 is within a range indicated in formula (1), 0.5<(D3 /D2 )<=0.95.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft type waste melting furnace having a free board portion.

[0002]

2. Description of the Related Art Development of waste treatment technology that pyrolyzes waste such as municipal solid waste and shredder dust into gas and then burns it to generate high-temperature gas, then melts the residue and turns it into slag for discharge. Is being promoted. This technology has attracted attention as a technology having the above-mentioned features and simultaneously achieving volume reduction of waste and insolubilization of heavy metals contained in residues. There are several types of melting furnaces for melting waste, one of which is a shaft type waste melting furnace.

[0003] This shaft type waste melting furnace, for example,
Japanese Patent Application Laid-Open No. 9-60830 discloses a configuration disclosed in Japanese Patent Application Laid-Open No. 9-60830, in which coke deposited on a furnace bottom is burned, and waste is charged onto the high-temperature coke, pyrolyzed and gasified. Next, it is a furnace of a type that performs a process of melting the pyrolysis residue to form slag. For this reason, in the shaft-type waste melting furnace, the functions of the furnace body are roughly divided into three in the vertical direction.

[0004] That is, a freeboard section having a large space is provided above the furnace body, a pyrolysis zone is provided continuously below the freeboard section, and a melting zone is provided below the pyrolysis zone. Have been. And, in this shaft type waste melting furnace, the lower part of the free board part is reduced in diameter to form a bosh shape, and a pyrolysis zone and a melting zone are provided continuously below the bosh narrow part. Have been. For this reason, this shaft type waste melting furnace
A large-diameter cylinder (the cylindrical portion of the freeboard portion) and a small-diameter cylinder (the portion of the pyrolysis zone and the melting zone) are joined via a bosh-shaped narrowed portion. Further, the freeboard section, the pyrolysis zone, and the melting zone are provided with tuyeres for blowing oxygen-containing gas, respectively.

[0005] In the pyrolysis zone, the input waste is deposited and pyrolyzed (dry distillation) to generate combustible gas. In the melting zone, coke introduced together with the waste is deposited and burned, and a process of melting the pyrolysis residue of the waste descending from the pyrolysis zone into molten slag is performed. At this time, the thermal decomposition residue of waste
A large amount of char is contained in addition to the ash and the non-combustible material, and this char is combusted together with the coke introduced together with the waste and becomes a heat source, so that there is an effect of reducing coke consumption.

[0006]

However, the above-mentioned conventional waste melting furnace has various problems. That is, in the operation of the above-mentioned conventional waste melting furnace, a shelving phenomenon occurs in which the residue of the waste pyrolyzed in the pyrolysis zone is difficult to drop to the melting zone at the bottom of the furnace, or stays at the bottom of the furnace. In some cases, the temperature of the molten slag decreases and the discharge of the molten slag becomes poor, which may hinder stable operation.

In addition, there is a problem that the heating at the furnace bottom is unevenly performed and the furnace wall at the furnace bottom is easily damaged.

Further, in order to reduce the amount of coke supplied as a heat source for melting the pyrolysis residue,
It is also desired to improve thermal efficiency.

[0009] The present invention solves the above-mentioned problems, enables stable operation to be continued, and reduces the amount of damage to the furnace wall.
It is another object of the present invention to provide a waste melting furnace in which the amount of coke used is reduced.

[0010]

Means for Solving the Problems The present inventors conducted a detailed study on the cause of the problem occurring in the above-mentioned conventional waste melting furnace based on operation data, and further conducted an experiment to confirm the study result. It was found that the cause was the structure of the lower part of the furnace. That is, in the conventional melting furnace, the lower part of the furnace has a shape as shown in JP-A-9-60830, and the portion of the pyrolysis zone and the portion of the melting zone having different functions are formed to have the same diameter. It has also been found that there is a problem in that the tuyere for blowing the oxygen-containing gas provided in the melting zone is not properly arranged.

The present invention has been made based on such findings, and has the following features.

The waste melting furnace according to the first aspect of the present invention has a free board portion, and has a sub-tuyere that blows an oxygen-containing gas continuously below the free board portion to accumulate waste. A pyrolysis section for performing pyrolysis by means of a main tuyere for blowing an oxygen-containing gas, and a melting section for burning deposited coke and melting a pyrolysis residue of waste falling from the pyrolysis section. In a shaft type waste melting furnace provided sequentially, an inner diameter D _{2 of a} pyrolysis section having an inner diameter D ₃ of a melting section.
(D ₃ / D ₂ ) is within the range shown in the equation (1).

0.5 <(D ₃ / D ₂ ) ≦ 0.95 (1) The waste melting furnace according to claim 2 of the present invention has a free board part, and the free melting part is provided below the free board part. It has a sub tuyere that blows oxygen-containing gas in series, a pyrolysis section that deposits and pyrolyzes waste, and a main tuyere that blows oxygen-containing gas, and burns the deposited coke to produce a high-temperature combustion zone. In a shaft-type waste melting furnace provided with a melting part for sequentially melting the pyrolysis residue of the waste descending from the pyrolysis part, a pitch circle at the tip of a plurality of main tuyeres is formed. It is characterized in that the ratio (d / D ₃ ) of the diameter d to the inner diameter D ₃ of the fusion zone is in the range shown in the equation (2).

0.2 ≦ (d / D ₃ ) ≦ 0.8 (2) The waste melting furnace according to claim 3 of the present invention has a free board portion, and is connected below the free board portion. A sub tuyere that blows oxygen-containing gas, a pyrolysis section that deposits and pyrolyzes waste, and a main tuyere that blows oxygen-containing gas, and burns the deposited coke to form a high-temperature combustion zone. In a shaft-type waste melting furnace provided with a melting part for sequentially forming and melting the pyrolysis residue of the waste descending from the pyrolysis part, a height h from the furnace bottom to the tip of the main tuyere is set. Ratio (h / D ₃ ) to the inner diameter D _{3 of the} fusion zone
Is in the range shown in equation (3).

0.3 ≦ (h / D ₃ ) ≦ 0.7 (3) The waste melting furnace according to claim 4 of the present invention has a free board portion, and is connected below the free board portion. A sub tuyere that blows oxygen-containing gas, a pyrolysis section that deposits and pyrolyzes waste, and a main tuyere that blows oxygen-containing gas, and burns the deposited coke to form a high-temperature combustion zone. In a shaft-type waste melting furnace provided with a melting part for sequentially forming and melting the pyrolysis residue of the waste descending from the pyrolysis part, a height h from the furnace bottom to the tip of the main tuyere is set. It is characterized in that the ratio (h / d) of the tip of the plurality of main tuyeres to the pitch circle diameter d is in the range shown in equation (4).

0.3 ≦ (h / d) ≦ 0.7 (4) The method for operating a waste melting furnace according to claim 5 of the present invention comprises:
The method for operating a shaft-type waste melting furnace according to claim 1, wherein the coke combustion load in the melting part is 70 kg / kg.
It is characterized in that charging the coke to be in the range of m ² h~120kg / m ² h.

In each of the above inventions, the ratio of the inner diameter of each part of the melting furnace is limited, but this ratio is the ratio of the inner diameter of the cylindrical part of each part.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory diagram relating to the configuration of a waste melting furnace according to the present invention. The melting furnace shown in FIG. 1 is a shaft-type waste melting furnace having a free board portion, and the functions of the furnace body are vertically divided into three. In the figure, A indicates the portion of the free board portion 10, B indicates the portion of the thermal decomposition portion 13, and C indicates the portion of the melting portion 15.

The free board section 10 is a space for lowering the flow rate of the gas in the furnace to prevent scattering of dust generated in the lower part of the furnace and for partially removing the pyrolysis gas (flammable gas) generated in the lower part of the furnace. A three-stage tuyere 23 that is provided for burning and maintaining the inside at a predetermined temperature, which is formed by a large-diameter cylindrical part 11 and a constricted part 12 reduced in diameter downward, and blows air. It has.

The pyrolysis section 13 partially burns the waste put in from the freeboard section 10 and deposited, and thermally decomposes the waste while slowly flowing the waste, and further heats the pyrolysis residue. It has a sub tuyere 22 which has a cylindrical shape, is formed continuously with the lower end of the throttle portion 12 of the free board portion, and blows air.

The melting section 15 burns the coke deposited from the free board section 10 and deposits it, and
Is a portion that melts the pyrolysis residue of the waste that descends from the furnace, and is formed by the constricted portion 16 and the cylindrical portion 17 that are provided at the lower end of the pyrolysis portion 13 and blows oxygen-enriched air. A main tuyere 21 is provided.

Reference numeral 18 denotes a loading port for coke and limestone as wastes and auxiliary materials, 19 an outlet for pyrolysis gas generated by pyrolysis of the input waste, and 20 a pyrolysis residue of the waste to a melting section 15. It is an outlet for the molten slag generated by the melting treatment at.

As described above, in this melting furnace, the cylindrical portion 11 of the freeboard portion, the cylindrical pyrolysis portion 13 and the cylindrical portion 17 of the melting portion are formed by the narrowing portion 12 of the freeboard portion and the narrowing portion of the melting portion. 16 are joined. For this reason, the cylindrical shape is drawn in two stages downward.

The shape or diameter in the description of each part of the melting furnace is indicated by the shape of the inner method or the size of the inner method.

In this melting furnace, the effects of the present invention can be obtained when the shape of the furnace lower part and the ratio of the dimensions of each part in the furnace lower part are in the following ranges.

A. The pyrolysis section 13 needs to be cylindrical. Even if the shape is not a perfect cylinder, it is desirable that the degree of aperture is small and the shape is almost a cylinder. When the pyrolysis section 13 has a cylindrical shape, a large proportion of the char obtained by carbonization of the organic waste reaches the melting section 15, and this char is used as an alternative heat source for coke in the melting section 15, and the amount of coke used. Is saved.

If the pyrolysis section 13 has a shape that is greatly constricted downward, the ascending flow rate of the gas in the furnace flowing in the pyrolysis section increases, and the char generated by the pyrolysis of the waste is generated. It scatters and burns with air blown from the upper tuyere. Therefore, the melting portion 15
And burns, and is no longer used as an alternative heat source for coke.

The ratio of the inner diameter D ₂ of the thermal decomposition part 13 to the inner diameter D ₁ of the cylindrical part 11 of the free board part is 0.3.
It is desirably in the range of 0.5 to 0.5.

B. The ratio (D ₃ / D ₂ ) of the inner diameter D ₃ of the cylindrical portion 17 of the melting portion to the inner diameter D ₂ of the thermal decomposition portion 13 needs to be in the range shown in the following equation (1).

0.5 <(D ₃ / D ₂ ) ≦ 0.95 (1) If (D ₃ / D ₂ ) is 0.5 or less, the thermal decomposition of the waste that descends from the thermal decomposition section 13 The residue does not come to the main tuyere and stays in the narrowed portion 16 of the melting portion, so that a shelf hanging phenomenon is likely to occur. This is because the inclination of the narrowed portion 16 of the melting portion is too gentle to lower the pyrolysis residue having a low bulk density to the furnace bottom.

When (D ₃ / D ₂ ) exceeds 0.95, the tip of the main tuyere 21 is too close to the furnace wall, and the furnace wall is damaged by the flame from the main tuyere. In addition, immediately above the main tuyere 21, the pyrolysis residue of the waste that has descended from the pyrolysis section 13 is suspended on the shelf due to the frictional resistance of the wall, and the unloading becomes unstable, resulting in coke and charcoal. The flames become unstable because they do not descend to the main tuyere.

Therefore, (D ₃ / D ₂ ) is 0.5 to 0.9.
In the melting furnace configured so as to fall within the range of 5, the shelf of the pyrolysis residue hardly occurs, and the furnace wall is hardly damaged.

C. The inner diameter D ₃ of the cylindrical portion 17 of the molten portion of the pitch circle diameter d of the tip of the plurality its dependent primarily tuyeres 21
Ratio (d / D ₃₎ is required to be in the range shown in the following equation (2) with respect to.

0.2 ≦ (d / D ₃ ) ≦ 0.8 (2) If (d / D ₃ ) is less than 0.2, the tip of the main tuyere 21 becomes too close to the center of the furnace. Because the heat supply is biased toward the center of the furnace, the degree of heating around the furnace wall is weakened,
The temperature of the molten slag around the furnace wall among the molten slag staying in the molten portion 15 decreases. For this reason, the viscosity of the molten slag around the furnace wall increases, and the molten slag is hardly discharged.

When (d / D ₃ ) exceeds 0.8, the tip of the main tuyere 21 becomes too close to the furnace wall, and the flame from the main tuyere 21 damages the furnace wall. Further, the supply of heat to the central portion of the furnace becomes insufficient, the temperature of the molten slag in the central portion of the furnace decreases, the viscosity increases, and the discharge of the molten slag becomes unstable.

Therefore, in the melting furnace configured so that (d / D ₃ ) is in the range of 0.2 to 0.8, the heating in the melting portion 15 is performed in a well-balanced manner so as not to be biased. Discharge of molten slag is performed smoothly. The main tuyere 2
1 is located at an appropriate position, the main tuyere 2
The problem of damage to the furnace wall by the flame from 1 does not occur.

In the melting furnace constructed so as to satisfy the expression (1) in addition to the expression (2), the thermal decomposition residue does not hang on the shelves, and the heating in the melting portion is carried out in a well-balanced manner. Since the molten slag is discharged smoothly, the operation of the melting furnace is performed more stably. Further, damage to the furnace wall of the melting furnace is further reduced.

D. It is necessary that the ratio (h / D ₃ ) of the height h from the furnace bottom to the tip of the main tuyere to the inner diameter D ₃ of the melted portion be in the range shown in the equation (3).

0.3 ≦ (h / D ₃ ) ≦ 0.7 (3) In particular, when the molten slag is intermittently discharged, the molten slag for about one hour is stored in the furnace bottom due to restrictions on the work interval. However, if (h / D ₃ ) is less than 0.3,
The capacity of the furnace bottom that stores the molten slag is too small,
A predetermined amount of molten slag cannot be stored. It is also feared that the capacity of the furnace bottom is too small and the main tuyere 21 is buried in the molten slag.

If (h / D ₃ ) exceeds 0.7, the capacity of the furnace bottom for storing the molten slag becomes too large, and the amount of heat dissipated by the stored molten slag increases. For this reason, the temperature of the molten slag decreases, the viscosity increases, and the discharge becomes unstable.

Therefore, (h / D ₃ ) is a value determined by the required storage amount of the molten slag and the heat distribution. For this reason,
In a melting furnace configured such that (h / D ₃ ) is in the range of 0.3 to 0.7, a predetermined amount of molten slag is stored and heat generated from the main tuyere is generated in the furnace bottom. Supplied in a well-balanced manner to each part, no low-temperature part is formed.
Therefore, the discharge of the molten slag is performed smoothly, and the operation can be stably continued.

In the melting furnace constructed so as to satisfy the expression (1) in addition to the expression (3), the thermal decomposition residue is not suspended on the shelf, and a predetermined amount of the molten slag is stored. At the same time, the furnace bottom is heated in the vertical direction in a well-balanced manner, so that a low-temperature portion is not formed, and the molten slag is discharged smoothly. Therefore, the operation of the melting furnace is performed more stably, and the stable operation can be continued.

E. Pitch circle diameter d at the tip of the main tuyere provided with a plurality of heights h from the furnace bottom to the tip of the main tuyere
Is required to be in the range shown in equation (4).

0.3 ≦ (h / d) ≦ 0.7 (4) If (h / d) is less than 0.3, the tip of the main tuyere generating a high temperature becomes too close to the furnace bottom, The molten slag is overheated abnormally, the slag foams and cannot be discharged, or the slag is vaporized, and the vaporized substance adheres to the furnace wall and sediment above and solidifies, causing the sediment to be suspended on the shelf .

In order to adjust the temperature in the melting section 15, an operation such as changing the oxygen concentration of the oxygen-enriched air blown from the main tuyere is performed, but (h / d) exceeds 0.7. In this case, there is a portion that is out of the range directly heated by the high-temperature gas generated from the main tuyere, so that the responsiveness of the temperature control is deteriorated, and the inside of the molten portion 15 is heated in a well-balanced manner. Disappears.

Therefore, in the melting furnace configured so that (h / d) is in the range of 0.3 to 0.7, the discharge of the molten slag can be carried out smoothly without the shelves of the sediment occurring. Therefore, the operation can be continued stably.

In the melting furnace constructed so as to satisfy the expression (1) in addition to the expression (4), the shelf of the pyrolysis residue is less likely to be suspended, and the inside of the melting portion is partially heated. The slag is discharged smoothly, and the operation of the melting furnace is further stabilized, and the stable operation is continued. can do.

In the operation of the melting furnace of the present invention, the coke combustion load in the melting part is 70 kg / m ^2.
h to 120 kg / m ² h.

If the coke combustion load is less than 70 kg / m ² h, the amount of heat in the melting part is insufficient, and the temperature of the molten slag and the furnace cannot be maintained in an appropriate temperature range. Becomes unstable.

When the coke combustion load exceeds 120 kg / m ² h, in order to supply oxygen required for combustion, in the case of oxygen-enriched air blowing, the blowing amount increases, the superficial velocity increases, and flooding ( The phenomenon that molten slag is blown up) frequently occurs. For this reason, the discharge of the molten slag becomes unstable.

When operating at the above superficial superficial speed,
Since the char generated by pyrolysis of the waste in the pyrolysis section is blown up and does not descend to the melting section, the char cannot be used for combustion, and the amount of coke used increases.

Therefore, when it is intended to make maximum use of fixed carbon derived from waste and reduce the amount of coke used,
It is an essential requirement that the coke combustion load be 120 kg / m ² h or less. And, the coke combustion load is 70
By performing the operation for charging the coke to be in the range of ^{kg / m 2 h~120kg / m 2} h, the molten slag together with the slag pyrolysis residue is melted is smoothly dropped is maintained at a proper temperature Is discharged smoothly. In addition, since the char generated by thermal decomposition of the waste can be used as a heat source, the amount of coke used can be reduced.

Next, the operation result of the melting furnace according to the configuration of the present invention and the operation result of the melting furnace according to the conventional configuration will be described. (Example) Using a shaft type waste melting furnace in which each part is formed in the following dimensions, gasification and melting of municipal waste was performed.

A. Furnace dimensions Inner diameter D ₁ of free board part: 2.3 m Inner diameter D _{2 of} pyrolysis part: 1.1 m Inner diameter D _{3 of} fusion part: 0.8 m Pitch circle diameter d of main tuyere tip: 0.5 m Main wing Height to mouth end h: 0.25 m Furnace bottom cross-sectional area: 0.50 m ² The ratio of the dimensions of each part is as follows.

The ratio (D ₃ / D ₂ ) of the inner diameter D _{3 of the} melting portion to the inner diameter D ₂ of the pyrolysis portion (D ₃ / D ₂ ) = 0.73 The ratio (d) of the diameter d of the pitch circle at the tip of the main tuyere to the inner diameter D ₃ of the melting portion. / D ₃ ) = 0.63 Ratio of the height h of the tip of the main tuyere to the inner diameter D ₃ of the molten portion (h / D ₃ ) = 0.31 The height h of the tip of the main tuyere and the pitch of the tip of the main tuyere Circle diameter d
(H / d) = 0.5 b. Operating conditions Municipal garbage charge: 1000 kg / h Coke supply: 50 kg / h (coke combustion load in the molten zone = 100 kg / m ² h) Limestone charge: 60 kg / h Main tuyere air supply: 274 Nm ³ / air h, oxygen 44Nm
³ / h (total blast oxygen = 102 Nm ³ / h) Charged fixed carbon: 65 kg / h from municipal solid waste (fixed carbon ratio 6.5%) 44 kg / h from coke (fixed carbon ratio 88%) 109 kg / h in total h Charged ash content (amount of molten slag): 100 kg / h from municipal waste (ash content 10%) 6 kg / h from coke (ash content 12%) 34 kg / h from limestone (ash content 56%) Total 140 kg / h fixed The amount of carbon / the amount of molten slag = 0.78 According to the operation results of the waste melting by the present inventors, the value of the fixed carbon amount / the amount of molten slag (0.78)
Is a value indicating that there is a sufficient amount of carbon as a heat source for supplying combustion heat for melting the pyrolysis residue and producing molten slag having favorable fluidity. According to the operation results, the lower limit of the amount of carbon required for melting the pyrolysis residue is such that the ratio of the amount of carbon to the amount of molten slag is about 0.5. For this reason, if all the charged fixed carbon becomes char as much as possible and enters the molten portion, the amount of coke used is reduced by the char.

The results of operation under the above operating conditions were as follows. Coke combustion cross section load is 100kg / m ²
h (50 kg / h), the amount of coke used was greatly reduced as compared with the case where a conventional melting furnace was used. This is considered to be because the amount of fixed carbon in the waste in the pyrolysis section was small, and much of the char generated by the pyrolysis was brought into the melting section and became an alternative heat source for coke.

Further, no shelving occurred between the pyrolysis section and the melting section, the molten slag was discharged smoothly, and a stable operation could be continued.

When the state of damage to the furnace wall of the fusion zone was examined after the halt, there was no degree of damage to the furnace wall, and a great effect was obtained as compared with the case where the melting furnace having the conventional configuration was used. .

(Comparative Example 1) An operation of gasifying and melting municipal solid waste was performed using a melting furnace having a conventional configuration disclosed in Japanese Patent Application Laid-Open No. 9-60830.

A. Furnace dimensions Inner diameter D of free board₁ : 2.3m, inner diameter D of pyrolysis section_Two : 1.1m Inner diameter D of the fusion zone_Three : 1.1m Pitch circle diameter d at the tip of the main tuyere: 1.0m Height h to the tip of the main tuyere: 0.5m Cross-sectional area of the furnace bottom: 0.95m^Two The ratio of the dimensions of each part is as follows.
Ratio of inner diameter of decomposition part (D_Three / D_Two ) And the tip of the main tuyere
(D / D) _Three ) Is a book
It was outside the scope of the invention.

The ratio (D ₃ / D ₂ ) of the inner diameter D _{3 of the} fusion zone to the inner diameter D ₂ of the pyrolysis zone (D ₃ / D ₂ ) = 1.0 The ratio (d) of the pitch circle diameter d at the tip of the main tuyere to the inner diameter D ₃ of the fusion zone. / D ₃ ) = 0.91 Ratio of the height h of the tip of the main tuyere to the inner diameter D ₃ of the molten portion (h / D ₃ ) = 0.45 The height h of the tip of the main tuyere and the pitch of the tip of the main tuyere Circle diameter d
(H / d) = 0.5 In this operation, shelving sometimes occurred between the thermal decomposition part and the melting part. Further, the temperature of the central portion of the molten portion may be lowered, and problems such as the difficulty in discharging the molten slag are caused. Further, in order to keep the discharge temperature of the molten slag from lowering, the amount of coke used could not be reduced to 80 kg / h or less.

After the stop, the furnace wall of the fusion zone was examined for damage.
It was damaged by about 00 mm, and required repair in a short time as compared with the case of the example.

(Comparative Example 2) The inner diameter D _{3 of the} melted portion was made smaller than that of the example, and was 0.55 m (furnace bottom sectional area =
0.24 m ² ), and the municipal solid waste is gasified by a melting furnace in which the ratio (D ₃ / D ₂ ) = 0.5 (outside the scope of the present invention) of the inner diameter D _{3 of the} melting part to the inner diameter D ₂ of the pyrolysis part And melted.

The operation results were as follows.

Coke combustion sectional load is 300 kg / m ² h
(72 kg / h), which was inferior to the coke combustion sectional load of 100 kg / m ² h (50 kg / h) in the example. Therefore, no effect on the reduction of the coke consumption as obtained in the examples was observed. This is considered to be because most of the char generated by the pyrolysis burned in the pyrolysis section, and most of the heat source in the melting section was covered by coke. The reason is by reducing the internal diameter D ₃ of the molten portion is believed that the melting unit is because it is formed in sharply constricted shape from the pyrolysis unit.

Accordingly, it was found that even if the inner diameter of the fusion zone was made smaller than the inner diameter of the thermal decomposition zone, the effect of reducing the amount of coke used would not be obtained unless the degree of reduction was proper.

Also, during operation, since the inner diameter of the melting portion was reduced, the flow rate of the gas in the furnace in the melting portion was increased (the superficial velocity was about twice as high as in the embodiment), and the molten slag was lifted. Floods began to occur frequently,
Discharge of molten slag sometimes became difficult.

[0068]

As described above, according to the present invention, the inner diameter of the melting portion for melting the pyrolysis residue of waste is made smaller than the inner diameter of the pyrolysis portion formed thereon, The ratio of the inner diameter of the fusion zone to the inner diameter of the appropriate range,
Further, since the main tuyere for blowing the oxygen-containing gas provided in the melting portion is arranged at an appropriate position, the following effects are obtained.

Most of the char generated in the pyrolysis section is carried into the melting section and burns in the melting section, so that the amount of coke supplied as a heat source for melting the pyrolysis residue is reduced.

In addition, the pyrolysis residue which descends from the pyrolysis section to the melting section is suspended on the shelves, and the unloading of the charge becomes worse, or the temperature of the molten slag stored in the melting section decreases. The problem that the discharge becomes abnormal does not occur, and the stable operation can be continued.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram relating to a configuration of a waste melting furnace of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Free board part 11 Cylindrical part of free board part 12 Restricted part of free board part 13 Thermal decomposition part 14 Cylindrical thermal decomposition part 15 Fused part 16 Restricted part of fused part 17 Cylindrical part of fused part 18 Waste and coke Limestone charging port 19 Pyrolysis gas outlet 20 Molten slag discharge port 21 Main tuyere 22 Secondary tuyere 23 Three-stage tuyere

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) F23G 5/50 F27B 1/12 4K045 F27B 1/12 1/16 1/16 B09B 3/00 303L (72) Inventor Yokoyama Yuichi History 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Yasuo Suzuki 1-1-2 Marunouchi, Chiyoda-ku, Tokyo F-term in Nihon Kokan Co., Ltd. (reference) 3K061 AA16 AB02 AB03 AC01 AC13 BA03 CA08 DB01 DB16 3K062 AA16 AB02 AB03 AC01 AC13 BB05 DA33 DB01 3K065 AA16 AB02 AB03 AC01 AC13 BA03 GA03 GA13 GA22 GA23 GA32 3K078 AA03 BA03 CA03 CA12 4D004 AA28 AA46 CA27 CA29 CB04K45 A02 GB01

Claims (5)

[Claims] A pyrolysis section having a free board section, and a sub-tuyere blowing under the free board section and blowing an oxygen-containing gas, wherein the pyrolysis section deposits and thermally decomposes waste; In a shaft-type waste melting furnace provided with a main tuyere for injecting, and provided with a melting section for sequentially burning the deposited coke and melting a pyrolysis residue of the waste descending from the pyrolysis section. A ratio (D ₃ / D ₂ ) of the inner diameter D ₃ of the section to the inner diameter D _{2 of the} pyrolysis section is in the range shown in the equation (1). 0.5 <(D ₃ / D ₂ ) ≦ 0.95 (1) 2. A pyrolysis section having a freeboard section, and a sub-tuyere continuous with the freeboard section for blowing an oxygen-containing gas, wherein the pyrolysis section deposits and thermally decomposes waste, and an oxygen-containing gas. A shaft type provided with a main tuyere that blows in, and a melting section for sequentially melting a pyrolysis residue of waste falling from the pyrolysis section while forming a high-temperature combustion zone by burning the deposited coke. In the waste melting furnace,
Pitch circle diameter d at the tip of a plurality of main tuyeres
The ratio (d / D ₃ ) of the melted portion to the inner diameter D ₃ is (2)
A waste melting furnace characterized by the range shown in the formula. 0.2 ≦ (d / D ₃ ) ≦ 0.8 (2) 3. A pyrolysis section having a free board section, a sub tuyere continuous with the free board section, and blowing an oxygen-containing gas, wherein a pyrolysis section for depositing and thermally decomposing waste is provided. A shaft type provided with a main tuyere that blows in, and a melting section for sequentially melting a pyrolysis residue of waste falling from the pyrolysis section while forming a high-temperature combustion zone by burning the deposited coke. In the waste melting furnace,
Inner diameter D ₃ of the melted part of height h from the furnace bottom to the tip of the main tuyere
A ratio (h / D ₃ ) to the range shown in the formula (3). 0.3 ≦ (h / D ₃ ) ≦ 0.7 (3) 4. A pyrolysis section having a free board section, a sub-tuyere continuous with the free board section, and blowing an oxygen-containing gas, wherein a pyrolysis section for depositing and thermally decomposing waste is provided. A shaft type provided with a main tuyere that blows in, and a melting section for sequentially melting a pyrolysis residue of waste falling from the pyrolysis section while forming a high-temperature combustion zone by burning the deposited coke. In the waste melting furnace,
The ratio of the height h from the furnace bottom to the tip of the main tuyere to the pitch circle diameter d of the tip of the plurality of main tuyeres provided (h
/ D) is in the range shown by the expression (4). 0.3 ≦ (h / d) ≦ 0.7 (4) 5. A operating method of a shaft type waste melting furnace according to claim 1, charging coke as coke combustion load in the molten portion is in the range of ^{70kg / m 2 h~120kg / m 2} h A method for operating a waste melting furnace.