JPH05288311A - Method for melting waste material and melting furnace applied for this method - Google Patents

Abstract

PURPOSE:To provide a melting method and a melting furnace for some intermediate processed materials got through drying, incinerating and crushing various municipal dusts, various industrial waste materials or other things capable of positively forming a high temperature fluidized bed required for performing a stable melting process. CONSTITUTION:A charging area for block-like carbonic combustible substances is formed at a higher location than that of tuyeres 1, 2 of a furnace and at an upper part within a furnace 3 while a spacing being left there. A loading cylinder 5 to which some waste materials A and some block-like carbonic combustible substances are loaded is buried and arranged from an upper part of a central part of a high temperature furnace bottom part 11 formed at a lower part of the charging region until its lower end reaches a higher location than that of tuyere. A plurality of block-like carbonic combustible substance loading ports 7 are arranged at an upper peripheral position of the furnace 3 while being spaced apart from the loading cylinder 5. More than one discharging gas feeding-out ports are opened into the spacing formed above the charging region for the block-like carbonic combustible substances within the furnace.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is directed to municipal solid waste, various industrial wastes, or intermediate products obtained by drying, incineration, crushing, etc., using a lumpy carbonaceous combustible substance such as coke as a heat source. The present invention relates to a melting method and a melting furnace for recovering as a slag material for civil engineering materials, concrete fine aggregates, surface makeup aggregates by heating and melting.

[0002]

2. Description of the Related Art In order to melt-process such waste, a waste mixed with coke together with limestone and silica as a basicity adjusting agent is charged from the top of a shaft furnace and oxygen-containing gas or oxygen-enriched from the tuyere. The gas is blown into the furnace, and the carbonaceous matter generated by coke and pyrolysis is burned at high temperature in the high-temperature hearth, and the dry zone, carbonization gasification zone, and combustion melting zone in the furnace are sequentially lowered to form molten slag. As for the high temperature combustion exhaust gas, the melting furnace itself, in which the waste packed bed in the shaft is raised as a counter flow to be recovered as a combustible gas, is disclosed in JP-A-55-82212 and JP-A-55-11.
It is disclosed in Japanese Patent No. 4382.

However, in this furnace, a large amount of oxygen-containing gas must be supplied in order to stably maintain the molten state of the waste, and especially when treating waste with poor air permeability, Unloading of waste becomes irregular and stable treatment becomes difficult.

In Japanese Patent Publication No. 63-49128, in order to prevent pollution and troubles in auxiliary equipment due to dust trapped and discharged in combustion exhaust gas in such a waste melting furnace, the top of the shaft furnace is prevented. A waste charging cylinder is provided in the center, the lower end is buried in the charging area, and coke is charged from the coke charging port arranged around the waste charging cylinder to fill the waste charging area. Is disclosed so that the filling area of the coke is covered so that dust blowing from the waste filling area due to exhaust gas is prevented by the coke suppressing action.

However, in this melting furnace, it is difficult to supply the massive carbonaceous combustible substance to the bottom of the furnace, and it is difficult to maintain the formation of the high temperature hearth. In addition, since the massive carbon-based combustible substance to be filled forms an angle of repose from the furnace core toward the peripheral wall, coarse particles with small ventilation pressure loss are formed in the peripheral wall portion where the filling height is low, and in the central portion where the filling height is high. Fine particles with large ventilation pressure loss will be distributed. Therefore, the high-temperature gas generated in the high-temperature hearth preferentially flows through the peripheral wall portion, resulting in wasteful loss of heat in the peripheral wall portion, insufficient preheating and drying of waste, and poor thermal efficiency. ..

Further, the applicant of the present application has filed Japanese Patent Application Laid-Open No. 3-561.
In order to solve the problems of increase of entrained dust and insufficient calorific value caused by uneven distribution of coke having different particle sizes, in the publication No. 1, a waste material, a lumpy carbon-based combustible substance, and a basicity adjusting material are provided in the central portion. It has been disclosed that the filling area of the carbonaceous combustible material is formed around the filling area of the same without forming a space.

The disclosed melting furnace eliminates the drawbacks of the conventional melting furnace and has the following various advantages.

[0008] Firstly, by filling a charging cylinder for charging the lumpy carbonaceous combustible substance together with the waste in the filling zone until the lower end reaches a position higher than the tuyere, the waste is filled. A heat source can be reliably supplied to the high-temperature hearth at the bottom of the layer, and the tuyere at the bottom is provided at the bottom of the cone with a small inner diameter, so the inner diameter of the furnace at the tip of the tuyere can be reduced, The air for forming the high-temperature hearth or the air enriched with oxygen can surely reach the furnace core, and the high-temperature hearth is reliably formed.

Further, by mainly passing the exhaust gas generated from the high-temperature hearth through a lumpy carbonaceous combustible material-filled layer having good air permeability, dust scattering from waste can be minimized and dust once scattered Also, the dust that is captured in the process of passing through the packed bed of lumpy carbonaceous combustible material, and the exhaust gas finally discharged from the furnace can be suppressed, and the gas flow in the furnace is improved because the packed bed has good air permeability. Can be stabilized.

Further, the dust trapped in the surrounding massive carbonaceous combustible substance gradually deteriorates the air permeability of the packing layer, but since the surrounding massive carbonaceous combustible substance is gradually burned and consumed, By bringing the captured dust into the high-temperature hearth in a dragged form, it becomes possible to melt the dust and maintain air permeability.

Further, the consumption rate of the lumpy carbonaceous combustible material in the surroundings can be changed by increasing or decreasing the amount of air supplied from the tuyere of the uppermost stage or the air enriched with oxygen, especially in the upper part. As a result, there is an advantage that the fuel cost can be minimized and the air permeability can be maintained.

However, in this melting furnace, there is no gas space above the bed of the agglomerated carbonaceous combustible material, and the exhaust gas pipe is connected to the agglomerated carbonaceous combustible material packed area. The large amount of dust contained in the exhaust gas is concentrated and adheres to the massive carbonaceous combustible substances, and the massive carbonaceous combustible substances adhere to each other due to the dust, resulting in air permeability and unloading of the massive carbonaceous combustible substances in the furnace. Is aggravated, which causes a new problem that the stable melting process is hindered.

[0013]

The problem to be solved by the present invention is to solve the problem and the gas caused by the exhaust gas containing a large amount of dust in the melting furnace, which is disclosed in the above-mentioned JP-A-3-5611, coming out from the gas outlet. SUMMARY OF THE INVENTION It is an object of the present invention to provide a melting method capable of reliably forming a high-temperature hearth necessary for performing stable melting processing by solving the problem caused by the uneven flow, and a furnace therefor.

[0014]

DISCLOSURE OF THE INVENTION The present invention provides a furnace body composed of a hollow cone having an upper portion enlarged and a lower portion charged with a lumped carbonaceous combustible substance having an inclined surface having an angle of repose or above. A method of melting waste by a waste melting furnace having a tuyeres of one or more stages at the lower part of the furnace body and a tap hole at a position lower than the tuyere, which is formed at the lower part of the filling area. Above the center of the high-temperature hearth, a filling area for the lumpy carbonaceous combustible material of the waste is formed, and a filling area for the lumpy carbonaceous combustible material is formed around the filling area of the waste and the lumpy carbon-based combustible material. And forming a space region above the filling region of the lump carbonaceous combustible substance formed around the filling region of the waste and the lump carbonaceous combustible substance.

Further, such a melting method has a furnace body composed of hollow cones having an upper portion enlarged and a lower portion charged with a lumped carbonaceous combustible material having an inclined surface having an angle of repose or above, In a waste melting furnace having a tuyere at the bottom of the furnace body and a tap hole at a position lower than the tuyere, a charging cylinder of the waste and the agglomerated carbonaceous combustible material from above the central part of the furnace body, The bottom end is inserted to a depth higher than the tuyere, a plurality of massive carbonaceous combustible material charging ports are provided around the upper part of the furnace body, and above the filling area of the massive carbonaceous combustible material in the furnace body. It can be carried out by using a waste melting furnace in which the exhaust gas outlet is opened in the space formed in.

Further, if necessary, the exhaust gas outlet port can be connected to an exhaust gas extraction pipe to a charging cylinder for charging the waste material and the lumpy carbonaceous combustible substance.

[0017]

Since a space is provided above the bed of the lumpy carbonaceous combustible material in the furnace body and the gas is discharged from the space with the flow velocity being sufficiently reduced, the exhaust gas can be discharged with less dust.

Further, by providing the charging port for the lumpy carbonaceous combustible material near the peripheral wall on the upper surface of the furnace body, the height of the lumpy carbonaceous combustible material packed layer charging surface can be set so that the peripheral wall portion is high and the furnace central portion is low. Because it can be formed in the furnace, it is possible to distribute the massive carbonaceous combustible material with a large particle size in the central part of the furnace, and the high temperature exhaust gas generated mainly in the high temperature hearth flows near the waste packed bed. It is easy to transfer the heat of waste to waste.

[0019]

EXAMPLE FIG. 1 shows an example in which coke is used as the lumpy carbonaceous combustible substance in the present invention, and FIG. 2 is a view showing a plane structure as seen from line AA in FIG.

In these figures, the waste melting furnace 10
Is a shape in which the diameter of the upper portion is expanded to 5 times the diameter of the cross-sectional portion of the lower tuyere 1 in the two-stage tuyeres 1 and 2 so that the superficial velocity of the combustion exhaust gas is reduced. Is composed of a hollow cone-shaped furnace body 3 having an inclination angle of 70 degrees or more. The inclination angle below the inner wall is in the case of using blast furnace coke having a diameter of 20 to 80 mm, including other dimensional ratios, for example, petroleum coke, pitch coke, electrode scrap, etc. It is preferable to change it depending on the property of.

Tuyers 1, 2 provided around the lower part of the furnace body 3
Are installed above and below, respectively, and preheated air is blown therein so that the coke in the furnace is burned to form a grate of a high temperature atmosphere.

Further, at the lower part of the furnace body 3, there is provided a tap hole 4 for discharging the slag of waste, incombustibles, coke, and ash of limestone, which is melted and mixed at a high temperature and the molten slag subjected to basicity adjustment is discharged. There is. It is also possible to provide a plurality of tap holes 4 of the same shape at equal intervals, use only one during operation, and install the furnace body by rotating it when restarting after the furnace is stopped and use them alternately. ..

From the center of the ceiling of the furnace body 3, waste A
The charging cylinder 5 for charging the coke B and the limestone C for adjusting the basicity of the melt is attached to the charging cylinder 5, and the waste A is discharged from the charging cylinder 5.
And 40 to 80% of the coke B are layered or mixed and charged together with the limestone C, and the tip is buried in the waste filling area 6 formed thereby, and the tuyere 1 of the upper stage is It has been inserted to a position above the level. The inner diameter of the charging cylinder 5 is 0.7 to 1.3 of the inner diameter of the upper tuyere 2.
Times, preferably 0.9 to 1.1 times. Reference numeral 7 denotes a coke charging port, and four coke charging ports are provided at positions as far as possible from the waste charging cylinder 5 around the upper surface of the furnace body 3. Reference numeral 8 denotes a gas exhaust pipe provided on one side of the ceiling of the furnace body 3, which is vertically connected so as to prevent dust accumulation. The gas exhaust pipe 8 can also be provided in the waste charging cylinder 5.

The numbers of the peripheral coke charging ports 7 and the gas exhaust pipes 8 are selected in an optimum combination according to the scale of the waste melting furnace and the equipment layout conditions around the furnace.

The coke B charged from each charging cylinder 5 and the charging inlet 7 is sieved in advance, and the one having a large particle size is charged into the charging cylinder 5, and the one having a small particle size is loaded into the peripheral coke. It is advisable to change the particle size of the coke so that it is charged into the inlet 7.

Reference numeral 9 indicates a coke filling region formed in the peripheral portion of the furnace by the coke B charged from the charging port 7.
Reference numeral 11 denotes a high-temperature hearth area formed right below the charging cylinder 5 in the center from the center near the furnace bottom.

The coke filling area 9 is formed so as to surround the waste filling area 6, and the upper surface thereof forms an angle of repose due to the falling of the charged coke.
A space area 12 is formed above.

The broken line shows the processing system of the combustion exhaust gas E, and the secondary combustion chamber 13, the air preheater 14, the gas cooler 15, the dust collector 16, the smoke washing device 1 are provided from the gas exhaust pipe 8 provided in the furnace.
7, an example is shown in which the air is discharged through the induction blower 18 and the chimney 19, but a recovery system as a combustible gas can also be used. Reference numeral 20 denotes a blower fan that sends the air preheated by the air preheater 14 to the tuyere 1, 2.

During the operation of this melting furnace, the waste A descends together with the coke B and the limestone C in the charging cylinder 5 to form the waste filling area 6. In this process, waste A, coke B, and limestone C are deposited in the charging cylinder 5 to a height of 500 to 800 mm. In this state, the waste A reaches 700 to 1000 ° C. in the lower center of the charging cylinder 5, and by the time it reaches the high-temperature hearth area 11, the ash and non-combustion are caused by the radiant heat from the red hot coke and the high temperature combustion exhaust gas from the combustion of the coke. The minutes rapidly soften, melt, melt, and drip the voids in the coke grate.

The coke B charged from the peripheral coke charging port 7 forms a coke filling region 9 in which heat exchange is performed while descending with the combustion exhaust gas discharged to the gas exhaust pipe 8, and the coke is When the temperature gradually increases and reaches the upper tuyere 2, it is further heated to a higher temperature and blown by the heat obtained by preferentially burning part of the CO gas in the combustion exhaust gas rising from below. Some of the oxygen burns the coke distributed around the inside of the charging cylinder. At this part, softening and melting of ash and incombustibles have started,
Although the rising gas is relatively difficult to pass through, a ring-shaped coke layer is formed on the peripheral wall side, and the rising gas passes through this portion having good air permeability.
At this time, the ascending gas maintains a uniform flow in the circumferential direction and the flow velocity is increased, so that heat transfer is promoted at the boundary below the waste filling region 6.

Further, in the high-temperature hearth area 11, the preheated air blown from the lower tuyeres 1 also uniformly burns the central coke supplied from the charging tube 5 to stabilize the high-temperature coke grate. Maintained.

In the case of this embodiment, the filling height in the furnace is about 2.5.
In m, the ventilation pressure loss of the packed bed is 100-200 mm water column, the space 12 is formed above the coke packed bed, and the gas is discharged with a sufficiently low flow velocity from the space, so that there is little dust entrainment. Emitted as gas.

Further, the upper tuyere 2 has 30 to 5 of blown air D.
Blowing in an amount of 0% is effective in lowering the coke combustion ratio, and raises the temperature of the molten slag to obtain stable tapping slag.

[0034]

According to the present invention, the following effects can be obtained.

(1) A high-temperature hearth is reliably formed, and even a waste with poor air permeability can be stably melt-processed while suppressing dust scattering and maintaining air permeability and unloading in the furnace, and preheating drying of exhaust gas. A waste melting furnace with high thermal efficiency can be realized by improving the effect.

(2) A charging cylinder for charging the lumpy carbonaceous combustible substance together with the waste is provided by embedding it in the filling zone until the lower end reaches a position higher than the tuyere. A heat source can be reliably supplied to the high-temperature hearth, and air for forming the high-temperature hearth or oxygen-enriched air can surely reach the core, thereby improving fuel efficiency.

(3) By mainly passing the exhaust gas generated from the high-temperature hearth through a lumpy carbonaceous combustible material-filled layer around the well-ventilated area, dust scattering from the waste can be minimized and once scattered. Dust can also be captured in the process of passing through the packed bed of carbonaceous combustible material, and the dust that accompanies the exhaust gas finally discharged from the furnace can be suppressed. Can be stabilized.

(4) The consumption rate of the lumpy carbonaceous combustible material in the surroundings can be changed particularly by increasing or decreasing the amount of air supplied from the tuyere of the uppermost stage or the air enriched with oxygen. As a result, the fuel cost can be controlled to such an extent that the fuel cost can be minimized and the air permeability can be maintained.

(5) A space is provided above the bed of the agglomerated carbonaceous combustible material in the furnace body, and in order to discharge the gas with a sufficiently low flow velocity from the space, it is possible to discharge the exhaust gas with less dust. it can.

(6) By providing the charging port for the lumpy carbonaceous combustible material near the peripheral wall of the hollow pyramid, the height of the lumpy carbonaceous combustible material packed layer charging surface is higher in the peripheral wall portion and lower in the central portion of the furnace. Since it can be formed into a state, it is possible to distribute massive carbonaceous combustible substances with a large particle size in the central part of the furnace, and it is possible for high temperature exhaust gas generated mainly in the high temperature hearth to flow near the waste packed bed. .. Therefore, the high-temperature exhaust gas accelerates the preheat drying of the waste, and the combustion cost can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a planar structure seen from line AA of FIG.

[Explanation of symbols]

 A waste B coke C limestone D blast air E combustion exhaust gas 1, two-stage tuyere 3 furnace body 4 tap hole 5 waste charging cylinder 6 waste filling area 7 coke charging port 8 gas exhaust pipe 9 coke filling area 10 Waste Melting Furnace 11 High-temperature Hearth Area 12 Space Area 13 Secondary Combustion Chamber 14 Air Preheater 15 Gas Cooler 16 Dust Collector 17 Smoke Washer 18 Induction Blower 19 Chimney 20 Blower Fan

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hirohisa Kajiyama 46-59 Nakahara, Tobata-ku, Kitakyushu-shi, Fukuoka 46-59 Nippon Machinery Works Co., Ltd. At 59 Nittetsu Plant Design Co., Ltd. at 46 Nakahara

Claims (3)

[Claims] 1. A furnace body having a hollow cone formed by an inclined surface having an angle of repose or more of an agglomerate carbonaceous combustible material having an enlarged upper portion and a lower charged portion, and a lower portion of the same. A method for melting waste by a waste melting furnace that has one or more tuyere and a tap hole at a position lower than the tuyere, above the central part of the high-temperature hearth formed in the lower part of the filling zone. Forming a filling area composed of the waste and the lumpy carbonaceous combustible substance, and forming a filling area of the lumpy carbonaceous combustible material around the filling area of the waste and the lumpy carbonaceous combustible material, and A waste melting method in which a space region is formed above a packed region of a lump carbonaceous combustible substance formed around a packed region of a waste and a lumpy carbon combustible substance. 2. The lump carbon-based combustible material forming the filling area of the waste and the lump-shaped carbon-based combustible material according to claim 1, has a diameter of 40 to 80 mm, and the lump carbon-based combustible material filling area. A waste melting method in which the lumpy carbonaceous combustible material that forms is smaller in diameter than that. 3. A furnace body comprising a hollow cone formed by an inclined surface having an angle of repose of a massive carbon-based combustible material, the upper part of which is enlarged and the lower part of which is charged, and the lower part of the furnace body. In a waste melting furnace having a tuyere and a tap hole at a position lower than the tuyere, a charging cylinder of waste and massive carbonaceous combustible material is provided from above the central part of the furnace body, and the lower end thereof is the tuyere. Inserted to a depth reaching a higher position, providing a plurality of massive carbonaceous combustible substance inlets around the upper portion of the furnace body, and a space formed above the filling region of the massive carbonaceous combustible substance in the furnace body A waste melting furnace with an exhaust gas outlet on the inside.