JP3585348B2 - Burner type ash melting furnace using fluff fuel - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a burner-type ash melting furnace for heating and melting incinerated ash and the like using fluff fuel obtained by drying and crushing municipal waste.
[0002]
[Prior art]
The conventional burner type ash melting furnace uses kerosene or heavy oil as fuel and increases the operating cost. Therefore, the present inventors have developed a fine-grained combustible fuel (hereinafter referred to as fluff fuel) formed from collected municipal waste. To use).
[0003]
[Problems to be solved by the invention]
However, fluff obtained by drying and crushing municipal solid waste has a low calorie and a coarse particle size, and thus has a problem that it has poor combustibility and cannot be heated to a heating temperature of 1400 ° C. necessary for melting ash. In order to solve this problem, it is necessary to take measures such as mixing and burning auxiliary fuel such as kerosene or fuel gas, or using oxygen-enriched air for combustion air.
[0004]
Therefore, the present invention solves the above-mentioned problems , and does not require auxiliary fuel or oxygen-enriched air, and uses a low-calorie fluff fuel to obtain a fluff fuel capable of obtaining a heating temperature required for melting ash. It is an object to provide a burner type ash melting furnace to be used.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a melting chamber in which a fluff burner using fine-grained combustibles as a fuel is arranged at the top, and ash is supplied at the bottom, and an intermediate part of the melting chamber. A throttle wall that narrows the cross-sectional area of the melting chamber, and a residence that prolongs the residence time of the fine-grained combustible fuel by blowing combustion air in the combustion space above the throttle wall in the same tangential direction as the turning direction of the flame flow of the fluff burner. And a stirring air nozzle which blows combustion air in a combustion space below the throttle wall in a direction opposite to the flame flow of the fluff burner to promote stirring and mixing of the fine-grained combustible fuel .
[0006]
According to the above configuration, the throttle wall prevents the diffusion of radiant heat and raises the temperature inside the furnace, thereby promoting the combustion of the fine-grained combustible fuel. Further, the combustion air blown from the retention air nozzle causes the flame By accelerating the swirling of the flow, the residence time of the fine-grained combustible fuel in the upper combustion space can be extended, thereby burning the fine-grained combustible fuel more effectively and increasing the ash heating temperature. The temperature required for melting the ash can be ensured without using auxiliary fuel or oxygen-enriched air.
[0007]
Furthermore, by injecting and agitating combustion air from a stirring air nozzle into a flame flow coming out of the opening of the throttle wall, the fine-grained combustible fuel is more effectively burned and the ash is heated to a high temperature. be able to.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Here, an embodiment of the ash melting furnace according to the present invention will be described with reference to FIGS.
As shown in FIG. 1, the burner type ash melting furnace includes an ash hopper 2, a preheating chamber 3, and a melting chamber 4 from the upstream side of the inclined bottom wall 1, and a pusher 5a and a pusher 5 are provided at the bottom of the ash hopper 2. An ash supply device 5 including a cylinder 5b is provided.
[0009]
The melting chamber 4 includes a top wall 4b of a cylindrical side wall 4a, and a fluff burner 6 using fluff, which is a fine-grained combustible material, is attached to an opening of the top wall 4b. The fluff burner 6 is provided with a fuel supply cylinder 6a to which fluff fuel is supplied by pneumatic air (primary combustion air) at an axial center position, and has a swirler 6c on its outer peripheral portion to supply secondary combustion air. A combustion air cylinder 6b to be supplied is arranged. Although not shown, an ignition device is provided.
[0010]
In the melting chamber 4, a throttle wall 7 for narrowing the cross section of the melting chamber 4 is provided at a middle portion of the side wall 4a by a central opening 7a so as to project from the inner peripheral surface. An upper combustion space 4A having a volume capable of sufficiently retaining combustion air and a lower combustion space 4B having a volume capable of sufficiently agitating fluff fuel and combustion air are formed. The aperture wall 7 has an area of the opening 7a set in a range of 1 / 1.5 to 1/6 of the sectional area of the melting chamber 4 (aperture ratio of 0.67 to 0.16), and the radiant heat of the flame flow is set. It is configured to prevent the diffusion of water and raise the temperature of the furnace to promote the combustion of fluff fuel. In order to make the flow of the flame flow smooth, a tapered surface 7b is formed on the upper surface of the throttle wall 7 and is inclined downward at the center.
[0011]
As shown in FIG. 2, a plurality of, for example, four stagnant air nozzles 8 penetrate and are disposed in the side wall 4a of the upper combustion space 4A, and burn in the tangential direction along the flame swirl flow a of the fluff burner 6. The air (tertiary combustion air) b is set to be blown. As a result, the swirling of the flame flow is further promoted, the residence time of the fluff fuel is extended to 1.5 to 2 times the conventional value, and the combustion rate of the fluff fuel can be improved.
[0012]
As shown in FIG. 3, a plurality of, for example, four agitating air nozzles 9 are provided through the side wall 4a of the lower combustion space 4B, and the combustion air flows in a direction opposite to the flame swirl flow a of the fluff burner 7. (Tertiary combustion air) It is set to blow c . As a result, the flame stream and the fluff fuel sufficiently retained in the upper combustion space 4A are mixed and agitated and burned at once, thereby generating high-temperature combustion heat and effectively heating and melting the ash A to generate a molten slag MS. be able to.
[0013]
In addition, as shown by a virtual line in FIG. 3, the stirring air nozzle 9 ' may be arranged so as to blow the combustion air d across the flame swirl flow a.
An exhaust gas duct 11 is connected to the top of the preheating chamber 3, and the melted combustion exhaust gas G is transferred to the inclined floor 1 by a countercurrent method in which the direction of the ash A and the flow of the combustion exhaust gas G are opposite to each other. After being brought into contact with the ash A and preheated, the combustion exhaust gas G is discharged from the exhaust gas duct 11.
[0014]
A slag discharge port 12 for discharging the molten slag MS is formed at the downstream end of the melting chamber 4, and water granulation is performed below the slag discharge port 12 by water cooling the dropped and discharged molten slag MS to generate granulated slag WS. Pits 13 are arranged. Note that a scraper conveyor 13a for discharging the granulated slag WS is provided in the granulated pit 13.
[0015]
In the above configuration, the ash A supplied to the ash hopper 2 is sent by the ash supply device 5 from the preheating chamber 3 to the melting chamber 4 along the inclined bottom wall 1 by a predetermined amount, and the fluff discharged from the melting chamber 4 is discharged. The burner 6 is preheated by the combustion exhaust gas G. In the melting chamber 4, the fluff burner 6 is burned, and in the upper combustion space 4A narrowed by the throttle wall 7, the combustion air is blown from the retention air nozzle 8 in the same direction as the flame swirl flow a. The fuel is further accelerated, the residence time of the fluff fuel is extended, and good combustion is achieved. Further, since the combustion heat generated in the upper combustion space 4A is prevented from being diffused by the throttle wall 7, the melting chamber 4 is heated and heated to promote the combustion of the fluff fuel. Then, in the flame flow that has moved from the opening 7a of the throttle wall 7 to the lower combustion space 4B, the mixing and stirring of the fluff fuel is promoted by the combustion air blown from the stirring air nozzle 9, and the combustion is favorably performed. The ash A on 1 is heated to 1400 ° C. or more and melted to produce a molten slag MS. The molten slag MS is discharged from the slag discharge port 12 to the granulation pit 13 and is water-cooled to generate granulated slag WS.
[0016]
FIG. 4 shows a measurement result of the temperature at point P below the melting chamber 4 in the above configuration. Here, the diaphragm wall 7 is disposed at a position where the inner diameter d of the melting chamber 4 is 700 mm, the height H of the melting chamber 4 is 2000 mm, and the distance h from the ceiling wall 4b is 750 mm, and a fluff fuel having a calorific value of 3575 kcal / kg is used. The result of burning at 350 kg / hr is shown. The horizontal axis shows the drawing ratio and the vertical axis shows the temperature, and the experimental results appeared as shown by the solid line. However, the scale of the melting furnace, that is, the size of the melting chamber 4, the capacity of the fluff burner 6, and the processing capacity of the furnace could be increased. For example, the result showed that the temperature increased as shown by the imaginary line. As a result, the opening ratio of the opening 7a of the diaphragm wall 7 is appropriately 0.67 to 0.16. If the opening ratio deviates from this range, heating at 1400 ° C. or higher at which ash can be melted cannot be expected. all right.
[0017]
【The invention's effect】
As described above, according to the configuration of the present invention, the throttle wall prevents the diffusion of radiant heat and raises the temperature inside the furnace, thereby promoting the combustion of the fine-grained combustible fuel, and at the same time, the residence air nozzle. The combustion air blown from the air accelerates the turning of the flame flow to extend the residence time of the fine-grained combustible fuel in the upper combustion space. As a result, fine-grained combustible fuel can be more effectively burned and the ash heating temperature can be increased, ensuring the temperature required for ash melting without using auxiliary fuel or oxygen-enriched air. can do. Further, by injecting the combustion air from the agitating air nozzle into the flame flow exiting from the opening of the throttle wall and in the opposite direction to the flame flow and stirring, the fine-grained combustible fuel can be more effectively removed. The ash can be heated to a high temperature by burning.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an embodiment of a burner type ash melting furnace according to the present invention.
FIG. 2 is a plan sectional view of an upper combustion space.
FIG. 3 is a plan sectional view of a lower combustion space.
FIG. 4 is a graph showing experimental results of the burner type ash melting furnace.
[Explanation of symbols]
2 Ash hopper 3 Preheating chamber 4 Melting chamber 4A Upper combustion space 4B Lower combustion space 6 Flaff burner 6c Swirler 7 Throttle wall 7a Opening 8 Retention air nozzle 9 Stirring air nozzle A Ash MS Melt slag G Combustion exhaust gas

Claims (1)

A melting chamber in which a fluff burner using fine-grained combustibles as a fuel is arranged at the top and ash is supplied at the bottom;
A restricting wall disposed at an intermediate portion of the melting chamber to reduce a cross-sectional area of the melting chamber;
A residence air nozzle for blowing combustion air in the upper combustion space of the throttle wall in the same tangential direction as the turning direction of the flame flow of the fluff burner to extend the residence time of the fine-grained combustible fuel ,
A fluffing air nozzle that blows combustion air in a direction opposite to a flame flow of the fluff burner in a lower combustion space of the throttle wall to promote stirring and mixing of the fine-grained combustible fuel. Burner type ash melting furnace using fuel.

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