KR100610642B1 - Combustion melting furnace, combustion melting method, and generating system for utilizing waste heat - Google Patents

Abstract

The present invention is to form a reducing atmosphere with an air ratio of less than 1 and an oxidizing atmosphere with an air ratio of at least 1 in one combustion chamber.

In the combustion melting furnace 3 which consists of one combustion chamber 17 provided with the slag discharge port 13 and the combustion gas discharge port 15, the primary air supply nozzle 8 and the secondary air supply nozzle 10 are provided. , The primary air is swirled to form a primary combustion region in the vicinity of the slag outlet 13 which is a reducing atmosphere with an air ratio of less than one. Secondary air is supplied to the primary combustion gas to form a secondary combustion region of the oxidizing atmosphere near the combustion gas outlet 15.

Description

Combustion Melting Furnace, Combustion Melting Method and Waste Heat Generation System {COMBUSTION MELTING FURNACE, COMBUSTION MELTING METHOD, AND GENERATING SYSTEM FOR UTILIZING WASTE HEAT}

1 is a schematic view showing an embodiment of a waste treatment plant in which a melting furnace and a power generation apparatus for combustion of the present invention are set up;

FIG. 2 is a cross-sectional plan view of a secondary air supply nozzle installed in the combustion melting furnace of FIG. 1;

3 is a cross-sectional plan view of the primary air supply nozzle installed in the combustion melting furnace of FIG. 1;

4 is a cross-sectional plan view of a fuel particle supply nozzle installed in the combustion melting furnace of FIG. 1;

5 is a side cross-sectional view of a combustion melting furnace in which a secondary air supply nozzle is disposed between a fuel particle supply nozzle and a slag outlet;

6 is a side cross-sectional view of a combustion melting furnace in which a secondary air nozzle is disposed in a slag cooling container;

7 is a side cross-sectional view of a combustion melting furnace having means for returning flammable solid particles recovered by a dust removal apparatus to a combustion chamber;

Fig. 8A is a schematic diagram of a combustion melting furnace for explaining the effect of making the diameter of the combustion gas outlet smaller than the diameter of the slag outlet, and (B) shows the circumferential velocity distribution in the horizontal section of the combustion melting furnace. Degree,

Fig. 9 (A) is a schematic diagram of a combustion melting furnace showing the effect of narrowing the diameter of the combustion gas outlet, (B) is a diagram showing the circumferential velocity distribution in the horizontal section of the combustion melting furnace.

10 is a sectional side view of a combustion melting furnace in which powder is suspended in a slag cooling vessel;

11 is a side cross-sectional view of a combustion melting furnace equipped with a fuel supply nozzle and an ignition device;

12 is a plan sectional view showing a position where the primary air supply nozzle, the fuel supply nozzle and the ignition device are installed;

FIG. 13 is a plan sectional view showing an example in which a flame retardant supply nozzle is installed in a primary air supply nozzle. FIG.

※ Explanation of symbols for main parts of drawing

1: crushed waste 2: pyrolysis furnace

3: combustion furnace 4: slag recovery device

5: waste heat recovery boiler 6: dedusting device

7: Chimney 8: Primary air supply nozzle

9: fuel particle supply nozzle 10: secondary air supply nozzle

11 fuel particle 12 slag

13: slag outlet 14: slag cooling vessel

15 combustion gas outlet 17 combustion chamber

18: recovered particle supply nozzle 19: powder

20: flame retardant supply nozzle 21: ignition device

99: generator 100: steam turbine.

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a combustion smelting furnace which burns fuel particles made of a flammable solid material such as coal or a solid material obtained by thermal decomposition of municipal waste, and slags and recovers ash. The present invention also relates to a combustion melting method for performing combustion of fuel particles and melting of ash, and a power generation system using the heat of combustion of fuel particles.

With the increase in waste, the capacity of landfills for incineration ash is becoming insufficient. Therefore, the development of the equipment which melt | dissolves the ash discharged | emitted from an incinerator and reduces a volume is advancing.

But the second melting of the ash requires energy from the outside. On this issue, various systems for melting ashes by directly using the energy of waste are being studied. Particularly, waste is introduced into a pyrolysis apparatus and heated in a reducing atmosphere to produce pyrolysis gas and solid residues, and fuel particles excluding non-combustibles from solid residues are put into a combustion furnace for combustion, and ash is melted and slag recovered. The system is in the spotlight. This system is described, for example, in Japanese Unexamined Patent Publication No. 6-56253.

As for the combustion melting furnace, it is possible to see many types of combustion by rotating fuel particles and air, and are shown in, for example, Japanese Patent Laid-Open No. 2-150611.

The combustion melting furnace described in Japanese Patent Laid-Open No. 2-150611 has a waste burner device and an assist burner device at the lower part of a furnace main body. Each burner device has a plurality of nozzles in the furnace body circumferential direction, and these nozzles are arranged to form swirl flow.

The Japanese Laid-Open Patent Publication discloses that waste and auxiliaries supplied from a waste burner device and an assisting burner device flow upward in the furnace as upward swirl flows, and molten slag is discharged from the slag discharge port, while the combustion gas is discharged from the top of the furnace. It is described that the discharge from the combustion gas outlet of the. In addition, the air ratio in the melting furnace (primary combustion chamber) is narrowed to 1.0 to 0.6, and the remaining air is blown from the air intake hole of the secondary combustion chamber provided at the upper portion of the combustion gas discharge port and mixed with the combustion gas containing unburned combustion to completely burn it. It is described.

According to the combustion melting furnace described in Japanese Patent Laid-Open No. 2-150611, waste is burned at an air ratio of less than 1 in the primary combustion chamber, combustion gas containing unburned fraction is introduced into the secondary combustion chamber, and air is supplied. Complete combustion is performed at an air ratio of 1 or more.

In this way, two combustion chambers are provided to perform primary combustion with an air ratio of less than 1 and complete combustion with an air ratio of 1 or more. If primary combustion with an air ratio of less than 1 and secondary combustion with an air ratio of at least 1 can be performed in one combustion chamber, the structure of the combustion melting furnace can be simplified, and the practical effect is very large.

The present invention is to provide a molten combustion furnace in which one combustion chamber can perform primary combustion with an air ratio of less than one and secondary combustion with an air ratio of at least one. Another object is to provide a combustion method suitable for performing primary combustion and secondary combustion in a combustion chamber. Another object is to provide a power generation system using the heat of combustion in a combustion furnace.

The present invention resides in the combustion melting furnace, the combustion melting method and the power generation system described in (1) to (15) below.

(1) a combustion chamber for combusting fuel particles made of a combustible solid material, a combustion gas outlet for discharging combustion gas generated in the combustion chamber from the combustion chamber, a slag outlet for discharging molten slag generated in the combustion chamber from the combustion chamber, and A combustion melting furnace having a fuel particle supply nozzle for supplying fuel particles to a combustion chamber and an air supply nozzle for supplying combustion air to the combustion chamber, wherein the air supply nozzle is provided with a plurality of air supply nozzles, and the slag outlet has a reduction in air ratio of less than one. A combustion melting furnace characterized in that the atmosphere is arranged so that the combustion gas outlet is an oxidizing atmosphere with an air ratio of 1 or more.

According to the present invention, one combustion chamber can perform primary combustion with an air ratio of less than one, followed by secondary combustion with an air ratio of one or more. The combustion furnace of the present invention can separate the slag and the combustion gas because the outlet of the slag and the outlet of the combustion gas are separate.

(2) a combustion chamber for combusting fuel particles made of a combustible solid material, a combustion gas outlet for discharging combustion gas generated in the combustion chamber from the combustion chamber, a slag outlet for discharging molten slag generated in the combustion chamber from the combustion chamber, and In a combustion melting furnace having a fuel particle supply nozzle for supplying fuel particles to a combustion chamber and an air supply nozzle for supplying combustion air to the combustion chamber, the slag outlet is narrower than an inner diameter of the combustion chamber. A combustion melting furnace comprising: a first air supply nozzle for allowing air to flow in the direction of the slag discharge port; and a second air supply nozzle for allowing air to flow in the combustion chamber toward the direction of the combustion gas discharge port. .

The combustion melting furnace of the present invention does not flow toward the combustion gas outlet but the air supplied by the first air supply nozzle, so that the residence time of the fuel particles in the combustion chamber is increased, resulting in high combustibility. In addition, since the primary combustion of the fuel particles proceeds in the vicinity of the slag discharge port, the slag discharge port is maintained at a high temperature, so that molten slag is easily discharged.

(3) a combustion chamber for combusting fuel particles made of a combustible solid material, a combustion gas outlet for discharging combustion gas generated in the combustion chamber, a slag outlet for discharging molten slag generated in the combustion chamber, and supplying fuel particles to the combustion chamber In a combustion melting furnace having a fuel particle supply nozzle and an air supply nozzle for supplying combustion air to the combustion chamber, the diameter of the slag outlet is smaller than the inner diameter of the combustion chamber,

A primary air supply nozzle for forming swirl flow of the primary air along the inner circumferential surface of the combustion chamber;

A secondary air nozzle for ejecting secondary air toward the center of the combustion chamber or in a direction of rotation of the primary air,

And a fuel particle supply nozzle which is provided between the primary air supply nozzle and the slag outlet, and which has a swirl flow of fuel particles along an inner circumferential surface of the combustion chamber.

According to the combustion melting furnace of the present invention, the swirl flow of the primary air and the fuel particles or the swirl flow of the secondary air is formed again, so that the residence time of the fuel particles in the combustion chamber becomes longer, resulting in higher combustibility.

(4) a cross-sectional circular combustion chamber for combusting fuel particles made of a combustible solid material, a combustion gas outlet provided at an upper portion of the combustion chamber, a molten slag outlet provided at a lower portion of the combustion chamber, and supplying fuel particles to the combustion chamber; In a combustion melting furnace having a fuel particle supply nozzle and an air supply nozzle for supplying combustion air to the combustion chamber, the diameter of the slag outlet is smaller than the inner diameter of the combustion chamber,

A primary air supply nozzle configured to blow primary air in a tangential direction of the inner circumferential surface of the combustion chamber to form a primary air flow that swirls along the inner circumferential surface of the combustion chamber;

Secondary to blow off the secondary air toward the center of the combustion chamber or in the direction of rotation of the primary air in order to mix the secondary air with respect to the flow of the combustion gas rising through the center of the combustion chamber and toward the combustion gas outlet; Air supply nozzle,

And a fuel particle supply nozzle which is installed between the primary air supply nozzle and the slag outlet, and which ejects fuel particles in the tangential direction of the inner circumferential surface of the combustion chamber.

In the vertical combustion melting furnace, the present invention shows the most suitable furnace configuration in the case of performing the first combustion of less than the air ratio and the second combustion of the air ratio of one or more in one combustion chamber.

Since the combustion chamber has a circular cross section, swirl flow of primary air and fuel particles or swirl flow of secondary air is likely to be formed. When the primary air is ejected by the primary air supply nozzle toward the tangential direction of the inner circumferential surface of the combustion chamber, a swirl flow flowing in the direction of the slag outlet port is formed while turning along the wall surface of the combustion chamber. In this state, when fuel particles are supplied between the primary air supply nozzle and the slag discharge port, the fuel particles flow in the direction of the slag discharge port accompanied by the swirl flow of the primary air. When the fuel particles are ejected to form swirl flows, they are more likely to accompany the swirl flows of the primary air. It is also preferable that the direction of swirl flow of the primary air and the direction of swirl flow of the fuel particles are the same direction.

Since the diameter of the slag outlet is smaller than the inner diameter of the combustion chamber, the swirl flow of the primary air and fuel particles that have descended the combustion chamber toward the slag outlet is stagnant at the portion of the slag outlet. As a result, the primary combustion of the fuel particles easily proceeds in the vicinity of the slag discharge port. At the slag outlet, the combustion gas generated by combustion of the fuel particles rises toward the combustion gas outlet through the center of the combustion chamber. By supplying secondary air to the upward flow of the combustion gas, the unburned fraction and remaining fuel particles contained in the combustion gas can be secondary burned.

Radiant heat of the combustion gas flowing upward from the center of the combustion chamber also increases the combustibility of the combustibles present near the wall surface.

(5) The combustion melting furnace according to (4), wherein the secondary air supply nozzle is provided between the primary air supply nozzle and the combustion gas discharge port.

According to the present invention, secondary combustion can be performed between the secondary air supply nozzle and the combustion gas discharge port.

(6) The combustion melting furnace according to (4), wherein the secondary air supply nozzle is provided between the fuel particle supply nozzle and the slag outlet.

According to the present invention, secondary combustion can be performed near the center of the combustion melting furnace.

(7) The combustion melting furnace according to (4), wherein the secondary air supply nozzle is provided below the slag discharge port, and the secondary air is supplied to the combustion chamber through the slag discharge port.

According to the present invention, secondary combustion can be performed near the center of the combustion melting furnace, and secondary air can be supplied without inhibiting swirl flow in the furnace.

(8) The combustion melting furnace according to (4), wherein the diameter of the slag outlet is smaller than that of the combustion gas outlet.

According to the present invention, there is an effect that it is difficult to discharge the unburned combustibles from the slag outlet.

(9) The combustion melting furnace according to (4), wherein the slag discharge port has a circular cross section.

According to the present invention, there is an effect of suppressing the temperature drop around the slag outlet.

(10) The combustion melting furnace according to (4), wherein the slag discharge port has a slit cross section.

According to this invention, there exists an effect which can suppress generation | occurrence | production of slag splash by the swirl flow in a combustion chamber.

(11) a combustion chamber for combusting fuel particles made of a combustible solid material, a combustion gas outlet for discharging combustion gas generated in the combustion chamber, a slag outlet for discharging molten slag generated in the combustion chamber, and supplying fuel particles to the combustion chamber In a combustion melting furnace having a fuel particle supply nozzle and an air supply nozzle for supplying combustion air to the combustion chamber, the diameter of the slag outlet is smaller than the inner diameter of the combustion chamber,

A primary air supply nozzle for forming swirl flow of the primary air along the inner circumferential surface of the combustion chamber;

A secondary air supply nozzle for ejecting secondary air toward the center of the combustion chamber or in the direction of rotation of the primary air;

The fuel particle supply nozzle which is installed between the primary air supply nozzle and the slag outlet, for forming swirl flow of fuel particles along the inner circumferential surface of the combustion chamber;

Combustion gas recovery material returning means installed between the primary air supply nozzle and the slag outlet and returning a combustible solid material or ash recovered from the combustion gas discharged out of the furnace from the combustion gas outlet to the combustion chamber Combustion furnace, characterized in that provided with.

According to the present invention, the combustibles or ash discharged out of the furnace together with the combustion gas can be recovered and returned to the combustion melting furnace for combustion.

(12) a combustion chamber for combusting fuel particles made of a combustible solid material, a combustion gas outlet for discharging combustion gas generated in the combustion chamber, a slag outlet for discharging molten slag generated in the combustion chamber, and supplying fuel particles to the combustion chamber In a combustion melting furnace having a fuel particle supply nozzle and an air supply nozzle for supplying combustion air to the combustion chamber, the diameter of the slag outlet is smaller than the inner diameter of the combustion chamber,

A primary air supply nozzle for forming swirl flow of the primary air along the inner circumferential surface of the combustion chamber;

A secondary air supply nozzle for ejecting secondary air toward the center of the combustion chamber or in the direction of rotation of the primary air;

The fuel particle supply nozzle which is installed between the primary air supply nozzle and the slag outlet, for forming swirl flow of fuel particles along the inner circumferential surface of the combustion chamber;

A retardant supply nozzle for supplying a retardant to the combustion chamber;

A combustion melting furnace, characterized by comprising an ignition device of the supporting medium.

According to the present invention, the gas combusted with the supporting agent flows along the wall surface of the combustion chamber by swirl flow. Since the swirl flow has a long residence time and becomes a strong turbulence, the combustibility of the fuel particles can be improved.

(13) A fuel cell made of a combustible solid material and air are supplied to a cylindrical combustion chamber having an outlet of combustion gas at one end and an outlet of molten slag at the other end, and the fuel particles are combusted to burn the combustion gas. In the combustion melting method in which the molten slag generated by the combustion of the fuel particles is discharged from the gas outlet and discharged from the slag outlet.

  In the combustion chamber, two atmospheres having an air ratio of less than one reducing atmosphere and an air ratio of one or more oxidizing atmospheres are formed, the slag outlet is in a reducing atmosphere of less than one air ratio, and the combustion gas outlet is an oxidizing atmosphere of one or more air ratios. Combustion melting method characterized in that.

According to the present invention, primary combustion with an air ratio of 1 or less, followed by secondary combustion with an air ratio of 1 or more can be performed in one combustion chamber. Formation of nitrogen oxides can be suppressed by primary combustion with an air ratio of less than one. Moreover, combustible gases, such as carbon monoxide or a hydrocarbon, which were produced by primary combustion by the secondary combustion of an air ratio 1 or more can be combusted. In addition, fuel particles remaining in the primary combustion can be burned.

(14) A fuel cell made of a combustible solid material and air are supplied to a combustion chamber having a circular cross section having an outlet for combustion gas at the upper portion and an outlet for melting slag at the lower portion thereof, and the fuel particles are combusted to burn the combustion gas into the combustion gas. In the combustion melting method wherein the molten slag produced by the combustion of the fuel particles is discharged from the outlet and discharged from the slag outlet.

Forming a swirl flow of primary air along the inner circumferential surface of the combustion chamber, supplying the fuel particles with respect to the flow of the swirl flow of the primary air in the direction of the slag outlet, and passing the central portion of the combustion chamber through the And a secondary air is supplied to the flow of the combustion gas rising toward the direction of the combustion gas outlet to increase the oxygen concentration at the combustion gas outlet.

According to the present invention, the residence time of the fuel particles in the combustion chamber can be made longer to improve the combustibility.

(15) In a power generation system having a combustion melting furnace for performing combustion and melting of ash of fuel particles made of a combustible solid material, and a generator for recovering heat of combustion gas generated in the combustion melting furnace and driving a steam turbine to generate electricity. In the combustion furnace, the combustion chamber for burning fuel particles,

Combustion gas discharge port for discharging the combustion gas generated in the combustion chamber,

A slag outlet for discharging molten slag generated in the combustion chamber;

A primary air supply nozzle for forming swirl flow of the primary air along the inner circumferential surface of the combustion chamber;

A secondary air nozzle for ejecting secondary air toward the center of the combustion chamber or in the direction of rotation of the primary air;

A combustion furnace waste heat utilization power generation system, provided between the primary air nozzle and the slag outlet, and having a fuel particle supply nozzle for forming a swirl flow of the material to be processed along the inner circumferential surface of the combustion chamber. system.

According to the present invention, it is possible to construct a power generation system using heat of combustion in a molten combustion furnace.

In the combustion melting furnace and the combustion melting method of the present invention, the fuel particles are supplied as powder or particles in order to increase the combustibility. The shape of the particles is preferably spherical, but is not limited thereto. In the case of using municipal waste or mud as a raw material of fuel particles, it is preferable to dry them with a pyrolysis device and then supply them to the combustion melting furnace.

By the primary air supplied by the primary air supply nozzle, it is preferable that the slag outlet port is made into a reducing atmosphere with an air ratio of less than 1 and 0.8 or more. The temperature in the furnace is influenced by the air ratio, and the temperature in the furnace is the highest when the air ratio is around 1, especially about 0.9. Even if the air ratio is higher or lower than this, the temperature decreases. When the air ratio of the bottom portion of the furnace including the slag discharge port is within the above range, the temperature of the slag discharge port can be increased to about 1200 ° C. to 1300 ° C. when burning the fuel particles obtained by pyrolysis of municipal waste. The resulting ash can be melted and discharged from the slag outlet. In addition, solidification of the slag at the slag discharge port can be suppressed.

On the other hand, the air ratio of the combustion gas discharge port is preferably in the range of 1.0 to 1.3. If it is an air ratio in this range, the combustibles contained in the combustion gas produced | generated by primary combustion can be combusted and production | generation of dioxins can be suppressed.

In addition, in this invention, an air ratio is a ratio of the amount of air which completely burns a fixed amount of fuel, and the amount of air which actually exists. For example, 23.82 m 3 of air is required to completely burn 1 m 3 of propane. At this time, if 67.64m 3 of air actually exists with respect to 1m 3 of propane, the air ratio is 2.

<Example 1>

One embodiment of the present invention is shown in FIG. The crushed waste (1) is introduced into a pyrolysis furnace (2) using a rotary kiln or a fluidized bed and heated in a reducing atmosphere to pyrolyze to produce pyrolysis gas and fuel particles. The fuel particles are injected into the combustion melting furnace 3 to combust and melt slag the ash, and the slag 12 is recovered by the slag recovery device 4 after cooling. The combustion gas generated in the combustion melting furnace 3 is heat-exchanged by the waste heat recovery boiler 5, is then exhausted by the dedusting apparatus 6 and discharged from the chimney 7 into the atmosphere. The steam obtained by the waste heat recovery boiler 5 is introduced into the steam turbine 100 and converted into electrical energy by the generator 99.

Fly ash and unburned fuel particles recovered by the dust removal device 6 can be returned to the combustion melting furnace 3 for combustion.

Here, in the combustion melting furnace 3, a fuel particle supply nozzle 9 is disposed between the primary air supply nozzle 8 and the slag discharge port 13, and the primary air supply nozzle 8 and the combustion gas discharge port 15 are disposed. The case where the secondary air supply nozzle 10 is disposed between and will be described.

The combustion furnace 3 is provided with a secondary air supply nozzle 10 as shown in FIG. 2, and a primary air supply nozzle 8 as shown in FIG. 3. 4, the fuel particle supply nozzle 9 is provided. The combustion chamber 17 of the combustion melting furnace has a circular cross section so that it is easy to form swirl flows of primary air and fuel particles. The primary air supply nozzle 8 is provided to blow primary air along the inner circumferential surface of the combustion chamber 17. The fuel particle supply nozzle 9 is also provided to supply fuel particles 11 along the inner circumferential surface of the combustion chamber 17 like the primary air supply nozzle. The secondary air supply nozzle 10 is provided to supply secondary air from two opposite directions toward the central portion of the combustion chamber 17 having a circular cross section. Secondary air may also be swirling.

The combustion chamber 17 is formed with a downward flow while turning by the primary air introduced from the primary air supply nozzle 8. The fuel particles 11 carried by air by the fuel particle supply nozzles 9 provided below the primary air supply nozzles 8 and supplied to the combustion chamber are lowered accompanying the swirl flow of the primary air.

The fuel particles 11 emit volatiles first when the furnace of the combustion melting furnace is preheated. The volatiles burn out soon. Thereafter, the fuel particles 11 and the ash drop near the wall surface under the influence of the centrifugal force and stay while turning around the upper portion of the slag outlet 13 at the bottom of the furnace. At this time, the fuel particles are first burned, and the ash is melted by the heat of combustion. The molten ash becomes slag 12 and flows along the furnace bottom surface from the wall surface and discharged from the slag discharge port 13. The slag cooling container 14 is installed under the slag discharge port 13, and the water tank is installed in the slag cooling container. The slag 12 dropped from the slag discharge port is dropped into the water tank and quenched, and then recovered by the slag recovery device 4.

On the other hand, the combustion gas is reversed at the bottom of the combustion melting furnace 3 and rises past the central part. Secondary air is blown by the secondary air supply nozzle 10 to the risen combustion gas to burn the remaining combustibles, specifically, combustible gases such as carbon monoxide or hydrocarbons and unburned fuel particles.

At the periphery of the slag outlet 13, the amount of primary air is adjusted so that a reducing atmosphere with an air ratio of less than one is formed. In this embodiment, the area below the primary air supply nozzle is a reducing atmosphere having an air ratio of less than one. In FIG. 1, the area | region where the inside of a combustion chamber becomes pale gray is shown to be a reducing atmosphere.

In addition, the amount of secondary air is adjusted so that an oxidizing atmosphere of at least one air ratio is formed around the combustion gas outlet 15. In the case of this embodiment, the region above the secondary air supply nozzle is an oxidizing atmosphere with an air ratio of 1 or more. In FIG. 1, the white area | region in a combustion chamber shows that it is an oxidation atmosphere.

The total amount of air blown by the primary air supply nozzle 8 and the secondary air supply nozzle 10 is preferably 1.0 to 1.3 in terms of air ratio. Among the secondary air supplied by the secondary air supply nozzle 10, the amount rising along the wall of the combustion chamber cools the wall near the combustion gas outlet 15 so that the protection of the furnace outlet pipe wall and the It is effective in preventing adhesion.

If the fuel particle supply nozzle 9 is lower than the primary air supply nozzle 8, the fuel particles always fall in the direction of the slag discharge port 13, so the fuel particles supply nozzle 9 is shortened upward and unburned fuel particles flow out of the furnace. Can be prevented. In addition, since the fuel particles remain while turning around the upper portion of the slag discharge port 13 at the bottom of the furnace, the ambient temperature of the slag discharge port 13 is always maintained at a high temperature due to the combustion of the fuel particles.

By primary combustion in a reducing atmosphere with an air ratio of less than 1, generation of nitrogen oxides can be suppressed, and production of dioxins can be suppressed by the high temperature of the furnace at about 1300 ° C.

In addition, the pyrolysis gas generated in the pyrolysis furnace 2 may be mixed in each nozzle.

<Example 2>

In the combustion melting furnace 3, the fuel particle supply nozzle 9 is arranged between the primary air supply nozzle 8 and the slag discharge port 13, and the fuel particle supply nozzle 9 and the slag discharge port 13 are disposed. 5 shows an example in which the secondary air supply nozzles 10 are provided in between. The configuration of the primary air supply nozzle, the secondary air supply nozzle and the fuel particle supply nozzle are all the same as in Example 1. When the secondary air is supplied by the secondary air supply nozzle 10, the combustibles contained in the combustion gas rising to the center of the combustion chamber can be combusted again. The concentration of fuel particles in the vicinity of the furnace wall and the bottom of the furnace is high, reducing the air atmosphere to less than 1 air atmosphere, and in the center and top of the combustion chamber is an air atmosphere of more than 1 air ratio.

<Example 3>

In the combustion melting furnace 3, a fuel particle supply nozzle 9 is disposed between the primary air supply nozzle 8 and the slag outlet 13, and the secondary air supply nozzle 10 is disposed of the slag cooling vessel 14. The embodiment arrange | positioned inside is shown in FIG. When the secondary air is introduced into the combustion chamber from the secondary air supply nozzle 10, the secondary air and the combustion gas may be mixed in the slag cooling container 14 to combust the combustion gas including the combustible powder again. The vicinity of the furnace wall has a high concentration of fuel particles, which results in a reducing atmosphere of less than 1 air ratio, and the central portion of the combustion chamber becomes an oxidizing atmosphere of 1 or more air ratios.

<Example 4>

In FIG. 1, fly ash or unburned fuel particles recovered by the dust removal device 6 are supplied from the fuel particle supply nozzles back into the furnace, but as shown in FIG. 7, the primary air supply nozzle 8 and the slag discharge port 13 are shown. The recovered particle supply nozzle 18 may be provided between the two, and the recovered particles may be introduced into the furnace. As a result, the fly ash and the unburned fuel particles recovered by the dust removal device 6 are burned together with the fuel particles again.

Example 5

8A and 8B show an example in which the diameter r ₃ of the slag discharge port 13 is smaller than the diameter r _e of the combustion gas discharge port in the combustion melting furnace 3. (B) also shows the circumferential velocity distribution in the horizontal section of the furnace. The circumferential velocity distribution hardly changes in the vertical direction of the combustion chamber. The central root of the swirl flow is the forced swirl and the outer one is the combined swirl of the free swirl, which is the maximum near the boundary. If the circumferential speed V _θ is large, the centrifugal force F acting on the fuel particles or ash flying in the furnace also increases.

Where m is the mass of the particle and r is the distance from the central axis.

At this time, if the diameter r _{s of the} slag discharge port 13 is larger than the diameter r _e of the combustion gas discharge port 15, the circumferential velocity of the tip of the slag discharge port 13 decreases, so that the centrifugal force acting on the fuel particles is reduced. Becomes smaller. The fuel particles then easily enter the slag cooling vessel 14 from the end of the slag outlet 13, thereby reducing the time spent in the furnace. In addition, problems such as re-spreading of unburned fuel particles from the slag cooling vessel 14 and contact of the lower surface with the particles also occur. Thus, if the diameter r _s of the slag outlet 13 is smaller than the diameter r _e of the combustion gas outlet 15, the slag cooling vessel is not passed through the region having a large circumferential velocity, that is, the region having a large centrifugal force. The problem can be avoided because it is not possible to enter.

When the slag discharge port 13 is not circular, the distance from the center of the hole to the end of the slag discharge port 13 may be considered as the diameter r _s of the slag discharge port 13. However, it is not preferable to make the slag discharge port 13 extremely small in view of the discharge of slag.

<Example 6>

An example of the case where the diameter r _e of the combustion gas discharge port 15 in the combustion melting furnace 3 is made smaller is shown in FIGS. 9A and 9B. The circumferential speeds when the diameter r _e of the combustion gas outlet 15 is large and small are also shown. As can be seen from (B), when the diameter of the combustion gas outlet is reduced, the maximum of the circumferential velocity is increased by preserving the angular momentum, and the region with the strong centrifugal force is expanded into the furnace as compared with when the diameter is large. As a result, the ability to retain particles is improved, leading to an improvement in the combustion rate. The diameter r _{e of the} combustion gas outlet 15 can be widened to the same size as the furnace diameter r, but when the diameter r _e of the combustion gas outlet 15 is increased, the turning force decreases, so that the particles are in the center direction. It is anticipated that the flow rate of unburned content will increase as it is easy to move to.

However, if the diameter r _e of the combustion gas discharge port 15 is reduced, the pressure loss in the furnace is increased, and thus the furnace diameter r: the diameter r _e = 2 to 3: 1 of the discharge port of the combustion gas is preferable.

<Example 7>

10 shows an example in which the powder 19 is suspended in the slag cooling vessel 14 in the combustion melting furnace 3. Water in the slag cooling vessel evaporates due to radiant heat in the furnace, causing a decrease in the gas temperature in the furnace. Therefore, when the powder 19 is suspended in the slag cooling container 14 to form an absorber for radiation, the radiant flux does not reach the lower surface of the water, so that the evaporation of water can be suppressed. As the powder, soot generated from a burner for heating the ash or slag discharged from the combustion gas discharged port can be used. Fly ash and soot have a small particle diameter of about several micrometers and can be suspended in a slag cooling vessel.

<Example 8>

The starting method in the combustion melting furnace 3 is demonstrated based on FIG. 11 and FIG. The primary air introduced from the primary air supply nozzle is mixed with the flame retardant introduced from the fuel supply nozzle 20 provided at the same level as or lower than the primary air supply nozzle. In this case, a gas having a high calorific value such as propane may be used as the supporting agent. The gas mixed with the fuel and the air is ignited by the ignition device 21 installed on the furnace wall while descending near the wall while turning. The ignited gas becomes hot by combustion and continues to descend along the wall again. Since the swirl flow in the combustion melting furnace has a long residence time, which is a strong turbulent flow, the heat of the combustion gas is efficiently transferred to the furnace. This makes it possible to shorten the preheating time.

When the temperature at the slag discharge port 13 decreases and there is a possibility that a problem of solidification of the slag 12 may occur, the coagulant is used as the auxiliary fuel and the temperature around the slag discharge port 13 is adjusted.

The flame retardant supply nozzle 20 can also be provided in the primary air supply nozzle as shown in FIG.

In addition, in the above embodiment, the case where all the combustion chambers were installed in the vertical type was demonstrated, The present invention is applicable also when the combustion chamber is installed in the horizontal direction or when the combustion chamber is installed in the diagonal direction.

 According to the present invention, it is possible to form a primary combustion region composed of a reducing atmosphere having an air ratio of less than one in one combustion chamber and a secondary combustion region composed of an oxidizing atmosphere having an air ratio of one or more.

Claims (24)

delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete A combustion chamber having an outlet for combustion gas at one end and an outlet for molten slag at the other end, a fuel particle supply nozzle for supplying fuel particles made of a combustible solid material to the combustion chamber, and air for supplying combustion air to the combustion chamber In a combustion melting furnace having a supply nozzle, A primary air nozzle for allowing primary air to flow in the combustion chamber toward the slag outlet, and 2 for allowing secondary air to mix with respect to a flow of combustion gas in the combustion chamber toward the combustion gas outlet Having a primary air nozzle, the fuel particle supply nozzle such that the fuel particles accompany the flow of primary air supplied by the primary air nozzle, and by the primary air supplied by the primary air nozzle The slag outlet becomes a reducing atmosphere having an air ratio of less than 1, the secondary gas supplied by the secondary air nozzle causes the combustion gas outlet to be an oxidizing atmosphere of an air ratio of 1 or more, and from the primary air nozzle to the slag outlet. A combustion melting furnace, wherein the fuel particle supply nozzle is provided in between. The method of claim 16, And a primary air nozzle to form swirl flow of primary air along an inner circumferential surface of the combustion chamber. The method of claim 16, And the fuel particle supply nozzle to form swirl flow of the fuel particles along the inner circumferential surface of the combustion chamber. The method of claim 17, And the combustion chamber is circular in cross section and has the primary air nozzle to blow primary air in a tangential direction of the inner circumferential surface of the combustion chamber. A combustion chamber having an outlet for combustion gas at one end and an outlet for molten slag at the other end, a fuel particle supply nozzle for supplying fuel particles made of a combustible solid material to the combustion chamber, and air for supplying combustion air to the combustion chamber In a combustion melting furnace having a supply nozzle, A primary air nozzle for allowing primary air to flow in the combustion chamber toward the slag outlet, and 2 for allowing secondary air to mix with respect to a flow of combustion gas in the combustion chamber toward the combustion gas outlet Having a primary air nozzle, the fuel particle supply nozzle such that the fuel particles accompany the flow of primary air supplied by the primary air nozzle, and by the primary air supplied by the primary air nozzle The slag outlet becomes a reducing atmosphere with an air ratio of less than 1, the secondary gas supplied by the secondary air nozzles causes the combustion gas outlet to be an oxidizing atmosphere of an air ratio of 1 or more, and the combustion gas outlet is placed on top of the combustion chamber. And the slag outlet at the bottom of the combustion chamber, the lead through the center of the combustion chamber And having the secondary air nozzle so that secondary air is blown out with respect to the flow of the combustion gas rising toward the gas outlet, and the secondary air nozzle is provided between the primary air nozzle and the combustion gas outlet. Combustion furnace characterized in that. Supplying fuel particles and air made of a combustible solid material to a combustion chamber having an outlet of combustion gas at one end and an outlet of molten slag at the other end, combusting the fuel particles to discharge combustion gas from the combustion gas outlet, In the combustion melting method in which the molten slag generated by the combustion of the fuel particles is discharged from the slag discharge port, The primary air nozzle is supplied from the primary air nozzle so that the primary air flows in the combustion chamber in the direction of the slag discharge port, and the fuel particles are supplied from the fuel particle supply nozzle to accompany the flow of the primary air. And the fuel particle supply nozzle is installed between the primary air nozzle and the slag outlet, and the secondary air is mixed so that the secondary air is mixed with the flow of the combustion gas of the fuel particle toward the combustion gas outlet. And supplying the slag outlet by the primary air to a reducing atmosphere of less than an air ratio of 1, and mixing the secondary air with the combustion gas outlet as an oxidizing atmosphere having an air ratio of 1 or more. . The method of claim 21, The combustion chamber has the combustion gas outlet at the top, the molten slag outlet at the bottom, and forms a swirl flow of the primary air along the inner peripheral surface of the combustion chamber, the swirl flow of the primary air is the molten And supplying the fuel particles with respect to the flow toward the slag outlet, and supplying the secondary air with respect to the flow toward the combustion gas outlet with the combustion gas of the fuel particles combusted by the primary air. Combustion Melting Method. Supplying fuel particles and air made of a combustible solid material to a combustion chamber having an outlet of combustion gas at one end and an outlet of molten slag at the other end, combusting the fuel particles to discharge combustion gas from the combustion gas outlet, In the combustion melting method in which the molten slag generated by the combustion of the fuel particles is discharged from the slag discharge port, The primary air is supplied from the primary air nozzle so that the primary air flows in the combustion chamber in the direction of the slag outlet, and the fuel particles are supplied from the fuel particle supply nozzle to accompany the flow of the primary air. And having the combustion gas outlet at the top of the combustion chamber, having the slag outlet at the bottom of the combustion chamber, and allowing secondary air to be blown out against the flow of combustion gas rising toward the combustion gas outlet through the center of the combustion chamber. Having the secondary air nozzle, the secondary air nozzle is installed between the primary air nozzle and the combustion gas outlet, and the secondary air is directed to the flow of the combustion gas of the fuel particles toward the combustion gas outlet The secondary air is supplied so that the mixture is mixed, and the slag outlet is discharged by the primary air. A combustion melting method comprising a reducing atmosphere having an air ratio of less than 1 and the combustion gas outlet as an oxidation atmosphere having an air ratio of 1 or more by mixing the secondary air. A combustion melting furnace waste heat generation system, comprising: a combustion melting furnace according to claim 16, and a power generating device for recovering the heat retained by the combustion gas generated in the combustion melting furnace to drive a steam turbine.

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