JPH03125808A - Fluidized-bed type refuse incinerator - Google Patents

Abstract

PURPOSE:To make it possible to reduce the generation of harmful matters a great deal by providing a refuse charging port at a position that is offset from an eccentric throttling section at the upper section of the furnace body and providing between the eccentric throttling section and a gas cooling chamber a tertiary air supply nozzle and a burner which assist in combustion and at the same time placing a recombustion chamber with an eccentric throttling section on the connecting side with the gas cooling chamber. CONSTITUTION:The upper section of a furnace body 1 that is out of an eccentric throttle section 1a is provided with a dust chute 6 that opens to the central section of a sand layer section 4. The refuse, as it is charged and spread widely and crushed to pieces, is thermally decomposed and burned. The gases that are generated go to a combustion chamber 2 and the gases that are not burned are mixed with secondary air and burn, and go through the eccentric throttle section 1a in the upper section of the combustion chamber 2 and their upwardly directed flow is changed and they flow into a recombustion chamber 9 provided with an eccentric throttle section on the side of the connection with a gas cooling chamber 8 as they are being mixed. The gases that are contained in the secondary combustion gases and have not burned are reburned by the tertiary air that is blown into the recombustion chamber 9 from a tertiary air blowing-in nozzle 9n. And the combustion is always kept in a high temperature and stable condition, and the exhaust gases such as unburned carbon, carbon monoxide, diozine, etc. are completely burned.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is particularly applicable to incinerated waste (hereinafter referred to as garbage), which is so-called high-quality waste that contains a large amount of plastics.
The present invention relates to a fluidized bed waste incinerator that can reduce the amount of harmful substances contained in exhaust gas, such as carbon monoxide and dioxins, by effectively incinerating waste gas.

[Conventional technology]

As is well known, examples of waste incineration equipment for incinerating municipal waste include fluidized bed waste incinerators (hereinafter simply referred to as waste incinerators).
Garbage incineration facilities equipped with JJ furnaces are often used.

An example of the above-mentioned garbage incinerator will be explained below with reference to FIG. 5, which is a schematic diagram for explaining the configuration. The furnace body has an eccentric throttle part (la) which is eccentric and constricted, and a garbage inlet (6) for inputting garbage is provided on the side of the furnace body (1), and a garbage inlet (6) is provided in the lower part of the inside. is provided with a dispersion plate (3), on which a fluidized bed made of high-temperature sand, so-called a sand layer part (4) for incinerating waste, is formed, and above it, a sand layer part (4) is formed. A combustion chamber (2) is provided for burning the combustible gas generated in step (4).

Furthermore, in the upper part of the eccentric constriction part (1a) of the furnace body (1),
A gas cooling chamber (8) is provided in which the combustion exhaust gas is cooled to a predetermined temperature by cooling water sprayed from the outside through a cooling water spray nozzle (8n), and an exhaust gas outlet of this gas cooling chamber (8) is provided. Although not disclosed, the exhaust gas emitted from the side (8a) is discharged into the atmosphere from the chimney through an air preheater, a dust collector, and an induced fan in sequence.

On the other hand, a primary air supply port (7a) is sent to a wind box (7) provided between the bottom of the furnace body (1) and the distribution plate (3) from a primary air forced air blower 1 (not shown) provided outside. Air is supplied, and this primary air is blown into the sand layer section (4) through a plurality of aeration nozzles (3n) provided on the dispersion plate (3), and a secondary air forced blower is also used. Secondary air (not shown) flows into the combustion chamber (2) in the furnace body (1).
The secondary air is blown into this combustion chamber (2) through a secondary air blowing nozzle (21) that penetrates the cylindrical portion of the cylinder.

What projects downward from the center of the dispersion plate (3) into the furnace body (1) is a non-combustible material discharge port (5) for discharging non-combustible materials mixed in the waste out of the furnace. It is.

Hereinafter, the working mode of the garbage incinerator shaft having the above-mentioned structure will be explained.

The primary air supplied from the primary air forced blower into the wind box (7) through the primary air supply port (7a) is supplied to the diffuser nozzle (3).
n). The sand layer is created by adjusting the diameter of this nozzle and increasing the amount of air in the center of the furnace.
The sand in the sand layer [4] is blown up from the center and further dispersed toward the inner wall of the furnace body (1), and the lower sand layer flows along the slope of the dispersion plate (3) so that it gathers in the center again. A dust supply device (not shown) collects dust by a dust supply device (not shown) into the sand layer (4), which circulates through so-called convection flow (in the direction of the arrow shown in the figure) and is maintained at a temperature range of 650 to 800'C. When garbage is input through the input port (6), the input garbage is dispersed and crushed by the convection flow and heat of the sand constituting the sand layer (4), and is thermally decomposed and burned.
Generates combustion gas containing a large amount of unburned gas.

On the other hand, the non-combustibles mixed in the thrown garbage are discharged from the non-combustibles discharge port (5) to the bottom and outside of the furnace body (1) along with a portion of the sand in the sand layer (4).

The unburned gas in the combustion gas is stored in the upper combustion chamber (
2) for 2 to 5 seconds, at which time complete combustion is achieved by the secondary air blown in from the secondary air blowing nozzle (2n).

Next, the combustion exhaust gas that reaches the gas cooling chamber (8) from the combustion chamber (2) through the eccentric constriction (1a) in the upper part of the furnace body (1) is passed through the cooling water spray nozzle in this gas cooling chamber (8). The cooling water sprayed from (8n) is cooled to a predetermined temperature by the evaporation of ice particles, and is discharged into the atmosphere from the chimney through the air preheater, dust collector, and induced fan in sequence.

[Problem to be solved by the invention]

Although the garbage incinerator with the above configuration is useful in its own way,
From the perspective of its incineration capacity based on the type of waste, it still has problems as explained below.

Garbage to be incinerated is a mixture of various substances, and it varies greatly depending on the season and collection area.It is divided into three types depending on the amount of heat generated by combustion: low-quality garbage, basic garbage, and high-quality garbage. Furnace design plans are carried out by setting waste quality, but in recent years the proportion of plastics mixed into waste has increased, and 3,000 to 4,000 plastics are considered high-quality waste.
The amount of high-calorie waste (al/kg) is also increasing.

Therefore, harmful substances such as dioxins, which are generated by the combustion of plastics, etc., as well as hydrocarbons and carbon
In order to reliably decompose o gas, etc., it is necessary to maintain the exhaust gas at a high temperature at all times, but in order to prevent the temperature of the exhaust gas in the combustion chamber from decreasing due to the influence of the gas cooling chamber, it is necessary to The connection part with the cooling chamber is made eccentric,
Even during steady operation, the temperature of the combustion chamber is directly affected by fluctuations in the amount of waste supplied, waste calorific value, sand layer temperature, secondary air pressure, cooling water injection, etc. In addition to the large temperature fluctuations in the 750 to 950°C temperature range, the structure is such that unburned gas is combusted in one large combustion chamber, resulting in uneven gas flow and secondary air mixing within this combustion chamber. - It is difficult to reliably burn and decompose carbon oxides and dioxins due to the non-uniformity of the mixture. Large amounts were sometimes released into the environment, contributing to air pollution.

Furthermore, the generation of dioxins and the like increases due to the low exhaust gas temperature and unstable combustion timing, especially when the garbage incinerator starts up or stops operating.

Therefore, the present invention increases the combustion temperature in the re-combustion chamber following the combustion chamber of the waste incinerator and stabilizes it continuously. The objective is to provide a garbage incinerator that can significantly reduce the amount of unburned gas such as carbon monoxide, unburned carbon such as soot, and harmful substances such as dioxins, even when the incinerator is shut down.

[Means for solving Section V]

The present invention solves the above-mentioned problems by focusing on the combustion temperature of unburned gas in the combustion chamber of a garbage incinerator and continuously stabilizing it. The structure is above a fluidized bed in which the waste to be incinerated is thermally decomposed and primarily combusted by primary air supplied from mN at the bottom of the furnace body through a diffuser nozzle. Inside the furnace body in position,
Garbage comprising a combustion chamber into which a plurality of secondary air blowing nozzles penetrating the cough oven body are opened, and a gas cooling chamber above the eccentric twill at the top of the oven body for cooling the combustion exhaust gas to a predetermined temperature. In the incinerator, a waste inlet opening toward the center of the fluidized bed is provided at a position away from the eccentric traverse section at the top of the furnace body, and an external It is characterized by having a tertiary air supply nozzle for blowing tertiary air into the interior thereof and an auxiliary combustion burner, and a re-combustion chamber having an eccentric hem on the side connected to the gas cooling chamber.

[Function] According to the waste incinerator of the present invention, the gas generated by thermal decomposition and combustion while being stirred and crushed by sand flow and heat in the fluidized bed is combusted in the combustion chamber, and the combustion gas is regenerated. It rises toward the combustion chamber, its upward flow direction is changed by the eccentric traverse of the furnace body, and it flows into the reburning chamber while being mixed. Re-combustion is carried out by tertiary air blown in from the tertiary air blowing nozzle.

Since the re-combustion chamber is interposed between the combustion chamber and the gas cooling chamber by providing an eccentric cross section between the combustion chamber and the gas cooling chamber, the temperature inside the combustion chamber can be maintained at a higher temperature, thereby preventing influences from other components.

Furthermore, by using the auxiliary combustion burner provided in the afterburning chamber when starting up and stopping the operation of the waste incinerator, the inside temperature of the afterburning chamber can be reliably maintained at a high temperature from the beginning to the end of the operation.

The upward flow direction of the exhaust gas discharged from the re-combustion chamber is changed by the eccentric cross section, and the exhaust gas is cooled in the gas cooling chamber in the same way as the exhaust gas in a conventional waste incinerator, and then discharged into the atmosphere. Become.

〔Example〕

Embodiments of the present invention will be described with reference to Figures 1 to 4.

This first embodiment will be described below with reference to FIG. 1, which is a schematic structural explanatory diagram of a waste incinerator, and the same parts as the conventional ones are designated by the same reference numerals.

That is, the reference numeral (1) shown in Fig. 1 is a vertical furnace body that is eccentric in the vertical direction and has an eccentric tread (1a) whose eccentricity is narrowed, and near the bottom of this furnace body (1). There is a dispersion plate (3) having a plurality of aeration nozzles (3n) through which primary air passes, and a sand layer section (4) on which the thrown garbage is received and burned. In the interior above the sand layer section (4) and below the eccentric twill section (1a), air is blown into the interior from a plurality of secondary air blowing nozzles (2n) provided around the outer periphery. A combustion chamber (2) is formed in which combustible gas is combusted by secondary air. A waste inlet (6) opening toward the center of the sand layer part (4) was provided at the upper part of the furnace body (+) that was removed from the eccentric constriction part (1a).

On the other hand, a plurality of tertiary air blowing nozzles (9n
) and an auxiliary burner 0■, and an afterburning chamber (9) having an eccentric throttle part (9a) on the upper part, and a conventional reburning chamber (9) on the eccentric throttle part (9a) of the afterburning chamber (9). A gas cooling chamber (8n) equipped with a cooling water spray nozzle (8n) having the same configuration.
) was established.

As shown in the figure, the degree of eccentricity between the upper part of the furnace body (1), the gas cooling chamber (8), and the reburning chamber (9) is as follows: The inner wall of the eccentric portion of the reburning chamber (9) was set to such an extent that the inner wall of the eccentric portion of the reburning chamber (9) could be connected in a straight line (xl).

As a result, the radiant heat of the sand layer part (4) and the combustion chamber (2) can be reflected and absorbed by the upward wall of the combustion chamber (2) and the upward wall of the afterburning chamber (9), so that the afterburning chamber [9]
The internal temperature can be maintained at a high temperature.

On the other hand, the eccentric constriction part (9a) at the connection part with the gas cooling chamber (8)
By making it eccentric and directing it to the outside of this X-ray, this gas cooling chamber (8) becomes the afterburning chamber (9) and the combustion chamber (2).
The shape is such that it does not have a negative impact on the

Although not shown, the exhaust gas outlet (8a) side of the gas cooling chamber (8) is connected to the chimney through an air preheater, a dust collector, and an induced blower in sequence, as in the conventional case. Of course it will be.

Furthermore, although not shown in the figure, a primary air supply duct is connected to the wind box (7) between the bottom of the furnace body (1) and the distribution plate (3), and the secondary air Although not shown, each of the air blowing nozzle (2n) and the tertiary air blowing nozzle (9n) is connected with an air supply duct from the forced air blower, and also has a cooling water spray nozzle (not shown) in the gas cooling chamber (8). 8n) is supplied with cooling water from a cooling water supply device.

In addition, the plurality of rod-shaped rods that are installed through the side wall of the garbage incinerator (c) measure the temperature inside the garbage incinerator (hl), and the temperature inside the garbage incinerator (hl) is measured based on the measured temperature. 6) is a thermometer (S) used for control to maintain the temperature within a predetermined range.

The operation mode of the garbage incinerator (c) with the above configuration will be explained below.
When garbage is thrown into the sand layer (
4), and is effectively and widely dispersed and crushed by the convection flow of the sand in this sand layer (4), while being thermally decomposed and burned by the heat of the sand.

The gas thus generated reaches the combustion chamber (2), where the unburned gas among the gases is mixed with secondary air blown from the secondary air blowing nozzle (2n) and combusted. Next, the secondary combustion gas flows through the eccentric throttle part (2) at the top of the combustion chamber (2).
The upward flow is modified through 1a) and flows into the afterburning chamber (9) with mixing.

This secondary combustion gas causes the degree of temperature fluctuation in the combustion chamber (2),
Even if the combustion is incomplete due to the degree of uneven flow of the gas or the degree of non-uniform mixing with the secondary air, the unburned gas contained in the secondary combustion gas will be transferred to the tertiary air blowing nozzle. (
9n) into the reburning chamber (9).

In addition, even when the exhaust gas temperature is low and unstable when the garbage incinerator (h) starts up or stops, the afterburning chamber (
9) By using the auxiliary combustion burner OI installed in the
Regardless of the situation in the other combustion chambers (2), the inside of this re-combustion chamber (9) can always be maintained at a high temperature and in a stable state, and together with the injection of tertiary air, the exhaust gas can be completely combusted. can.

In this way, the gas generated by the thermal decomposition and primary combustion of garbage in the sand layer part (4) is transferred to the combustion chamber (2) and the afterburning chamber (
9), so that harmful substances such as unburned carbon, carbon monoxide, and dioxins can be more reliably combusted during the operation period of the garbage incinerator (5).

Moreover, as mentioned above, the waste is quickly dispersed by the sand flow in the sand layer (4), so the thermal decomposition and primary combustion of the waste are stabilized, and the amount of unburned gas generated in the combustion chamber (2) is also reduced. It has been found that this can be an extremely effective means for preventing the discharge of harmful substances such as carbon oxide and dioxins.

Moreover, as mentioned above, the sand layer part (4) and the combustion chamber (2
) and the upper wall of the afterburning chamber (9) reflect and absorb radiant heat, so that the temperature inside the afterburning chamber (9) decreases to 90°C.
It became possible to stably maintain a high temperature in the range of 0 to 1100°C, and it was extremely effective for the combustion of -a carbon and the decomposition of dioxins and the like.

That is, secondary air with an air ratio of 0.4 to 0.6 is supplied to this combustion chamber (2) to ensure a gas residence time of 2 to 4 seconds, and an air ratio of 0 to 0.6 is supplied to the reburning chamber (9). By supplying tertiary air at 2 to 0°C and ensuring a gas residence time of 1 to 2 seconds, the temperature inside the afterburning chamber (9) can be maintained within the range of 900 to 1100°C. can.

This allows the air preheater, dust collector,
The content of carbon monoxide in the exhaust gas emitted into the atmosphere from the chimney can be suppressed to 50 ppm or less (previously 100 to 500 ppm) by sequentially installing induced blowers, and the amount of harmful substances such as dioxins emitted is also significantly reduced. It became possible to suppress the

11. This second embodiment will be explained based on the schematic configuration explanatory diagram No. 21; Only the points that are different in structure from the first embodiment will be explained below.

That is, a pair of auxiliary combustion burners (IOa) each having a fuel injection port opened on the opposing inner sides of a reburning chamber (9) having a rectangular cross section.
and (10b).

Therefore, this pair of auxiliary burners (1
0a) and (10b) to cover the front, and the combustion chamber (
The unburned gas contained in the secondary combustion gas rising from 2) is reliably and more effectively combusted even if it is low-temperature incompletely combusted gas at the time of startup or shutdown of the garbage incinerator. Therefore, its operation and effect are the same as those of the first embodiment.

Furthermore, in this embodiment, in order to particularly reduce dioxins, the inside of the afterburning chamber (9) is always kept at a high temperature (1000°C), and when performing so-called high temperature combustion, the auxiliary burner 00) in the afterburning chamber (9) It is effective in heating even during normal operation and maintaining the temperature inside the reburning chamber (9) at a high temperature.

1. This third embodiment will be described below with reference to FIG. 3, which is a schematic diagram showing the main parts thereof, and only the points that are structurally different from the first embodiment.

That is, on the inlet side of the reburning chamber (9), there is a tertiary air blowing opening on the inner surface of the refractory orifice (10 on the same stage and this orifice Ql) having a triangular cross section with the apex facing inward. The configuration includes a nozzle (9n).

Therefore, from the combustion chamber [2] through this inlet, the afterburning chamber (
The gas flowing into 9) is mixed by changing its upward flow direction by this orifice 00, and the force of the tertiary air blown into the afterburning chamber (9) from the tertiary air blowing nozzle (9n) is increased. Since the gas is effectively mixed with the blown tertiary air, its action and effect are the same as in the first embodiment.

However, as shown in the same figure, this orifice OD does not need to be annular, extending over the entire inner periphery of the inlet of the afterburning chamber (9); It is also possible to have a configuration in which the orifice protrudes from the
Even if there is no tertiary air blowing nozzle (9n) that opens on the inner peripheral surface side of the orifice 01), the gas flow is mixed by this orifice 01), so a gas agitation effect can be expected between the passages and the like.

Construction soil tip 5■ This fourth embodiment was constructed based on Figure 4a, which is a schematic explanatory drawing showing the main parts, and Figure 4, which is a view from the ■ arrow in Figure 4a. Only the points that are different in structure from the embodiment will be explained below.

That is, it opens at a central position near the opening of the tertiary air blowing nozzle (9n) that opens inward from the outer periphery of the afterburning chamber (9), and burns from above the furnace body (1) that has come off the eccentric arbor (la). A configuration was adopted in which a secondary combustion gas introduction pipe 02) was provided to guide a part of the secondary combustion gas in the chamber (2).

Therefore, the combustion chamber (2
) is sucked in, flows into the re-combustion chamber (9) from the secondary combustion gas introduction pipe 021, and enters the combustion chamber (2).
) is effectively stirred together with the gas flowing into the afterburning chamber (9) through this inlet, so its action and effect are the same as in the first embodiment.

In addition, by branching and mixing the secondary combustion gas, the amount of NOx generated in the afterburning chamber (9) is increased! Can be reduced to the corner.

The above-mentioned embodiments are merely specific examples of the present invention, and therefore, the scope of the technical idea of the present invention is not limited by these embodiments, and furthermore, within the scope of this technical idea, Design changes etc. can be made freely.

〔Effect of the invention〕

As detailed above, according to the garbage incinerator of the present invention, 1. The gas generated by thermal decomposition and combustion while being stirred and crushed by the convective flow and heat of the sand in the sand layer of the fluidized bed rises toward the combustion chamber, and the upward flow direction is changed by the eccentric ridge of the furnace body. , and flows into the re-combustion chamber while being mixed, and the unburned gas contained in the combustion gas in this re-combustion chamber is combusted by the tertiary air blown from the tertiary air blowing nozzle. The amount of unburned gas is smaller compared to the previous model, and it has become possible to significantly reduce the amount of soot emitted from carbon monoxide and unburned carbon contained in the exhaust gas.

Furthermore, since the re-combustion chamber is interposed between the combustion chamber and the gas cooling chamber by providing an eccentric traverse section between the combustion chamber and the gas cooling chamber, the temperature reduction effect of the gas cooling chamber on the temperature inside each combustion chamber is reduced, and the As the temperature inside the re-combustion chamber can be maintained at a higher temperature than the conventional combustion chamber, it is possible to maintain the temperature inside the re-combustion chamber at a higher temperature than the conventional combustion chamber. However, it has become possible to sufficiently combust the dioxins generated by this, making it possible to significantly reduce the amount of dioxins in exhaust gas.In addition, an auxiliary burner is installed in the afterburning chamber. By installing this, the amount of emissions of various harmful substances and unnatural substances including dioxins can be significantly reduced not only during normal operation of the garbage incinerator, but also during the entire operation of the garbage incinerator, including when starting up and stopping the operation. It is now possible to reduce

In addition, the garbage inlet is provided at the top of the furnace body so that the garbage can be thrown into the center of the sand layer, so the garbage is quickly dispersed by the convection flow of the sand in the sand layer, so the garbage can be heated stably. By making decomposition and combustion possible, temperature fluctuations within the combustion chamber are reduced, large incombustible materials can also be extracted from the center, and the lifespan of refractories such as firebricks placed on the inner walls of the garbage incinerator is reduced. It has also had the effect of reducing maintenance costs by making it possible to extend the time period.

Therefore, the present invention is extremely superior in that it can significantly reduce the amount of unburned gas such as carbon monoxide, unburned carbon such as soot, and harmful substances such as dioxins when incinerating high-calorie waste such as plastics. As a result, we were able to create a waste incinerator that uses

[Brief explanation of the drawing]

Fig. 1 is a schematic structural explanatory diagram of a waste incinerator according to the first embodiment, Fig. 2 a is a schematic structural explanatory diagram showing the main parts of the waste incinerator according to the second embodiment, Figure 2a is a sectional view taken along the line ■-■ in Figure 2a, Figure 3 is a schematic structural explanatory diagram showing the main parts of the garbage incinerator according to the third embodiment, and Figure 4a is the garbage incinerator according to the fourth embodiment. FIG. 4 is a schematic structural explanatory diagram showing the main parts of FIG. 4A, and FIG. 5 is a schematic structural explanatory diagram of a conventional garbage incinerator.

Claims (1)

[Claims] (1) Above the fluidized bed where the waste to be incinerated is thermally decomposed and primarily combusted by the primary air supplied from the wind box at the bottom of the furnace body through the aeration nozzle, which is introduced through the waste supply port provided in the furnace body. A combustion chamber is provided inside the furnace body at a position where a plurality of secondary air blowing nozzles that penetrate the furnace body open, and a combustion chamber is provided above the eccentric constriction at the top of the furnace body to cool the combustion exhaust gas to a predetermined temperature. In a fluidized bed waste incinerator equipped with a gas cooling chamber, a waste inlet opening toward the center of the fluidized bed is provided at a position away from the eccentric constriction at the top of the furnace body, and A re-combustion chamber having a tertiary air blowing nozzle for blowing tertiary air into the interior from the outside and an auxiliary combustion burner between the eccentric throttle part and the gas cooling chamber, and having an eccentric throttle part on the side connected to the gas cooling chamber. A fluidized bed waste incinerator characterized by being equipped with.