JPH03225106A - Method of suppressing generation of dioxine in garbage incinerator - Google Patents

Abstract

PURPOSE:To suppress the generation of dioxine before it is generated by providing more than three air supply nozzles at the circumferential wall of a secondary combustion chamber and supplying secondary air toward the contact point with a horizontal, imaginary circle in the room. CONSTITUTION:Four secondary-air supply nozzles 10, for instance, are provided at the circumferential wall 2a of the secondary combustion chamber 2 of a garbage incinerator with the blow-out holes at their tip ends pointing in the direction of the tangential line to a horizontal, imaginary circle C, and the ends of the secondary air supply nozzles 10 are respectively located on the four sides of a horizontal imaginary square S with its center at the center of the circle C. Supposing that the length of one side of the horizontal, imaginary square S is L and the diameter of the horizontal, imaginary circle C is D, the value L/D is preferably 5 - 15. With this constitution the combustion gas and the secondary air are mixed ideally and secondary combustion is made with an improved secondary combustion efficiency and the proportion of unburned garbage is much reduced. Accordingly the amount of matters that are contained in the unburned garbage and are precedent to dioxine is also reduced a great deal, and the exhaust gas that does not contain dioxine is discharged to the atmosphere. Furthermore, since the proportion of unburned dusts is reduced, the generation of NOx is also repressed.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention prevents the generation of dioxins when incinerating garbage in a garbage incinerator used for incinerating municipal waste, industrial waste, etc. Regarding the method.

[Prior art and its problems] Although there are many unknowns about the production process of dioxins discharged from garbage incinerators, it has been found that the amount of dioxins produced increases as the amount of unburned substances increases. This is thought to be because the unburned components contain a large amount of dioxin precursors.

Although dioxins are only contained in trace amounts in exhaust gas, they are extremely toxic to the human body even in trace amounts, and are particularly carcinogenic.Dioxins have recently come under the spotlight as a new pollution problem caused by waste incinerator exhaust gas. It is being done.

As shown in Figure 4, a conventional garbage incinerator has a primary combustion chamber (1) inside it, a secondary combustion chamber (2) provided above the primary combustion chamber (1), and a secondary combustion chamber (2) provided above the primary combustion chamber (1). a gas exhaust path (4) that guides combustion gas generated in the secondary combustion chamber (2) to the top outlet (3);
It includes an exhaust heat recovery device (5) and an exhaust gas cooling heat exchanger (6) provided near the top outlet (3) in the gas exhaust path (4). Garbage (R) is stored in the primary combustion chamber (1
) is placed on the grate (7) provided in the grate (
7) The primary air supplied from below is used for combustion. Two upper and lower secondary air supply nozzles (8) are provided on one side surface of the peripheral wall (2a) of the secondary combustion chamber (2).

The primary combustion gas is mixed with the secondary air supplied into the secondary combustion chamber (2) through the nozzle (8), is subjected to secondary combustion, passes through the gas exhaust path (4), and recovers exhaust heat. Device(
5) and a heat exchanger (6) to be cooled and then discharged from the top outlet (3) and sent to an exhaust gas treatment device (not shown).

However, in conventional incinerators, the primary combustion gas and secondary air are not sufficiently mixed in the secondary combustion chamber (2), and a large amount of unburned matter remains, reducing the amount of dioxins generated. I couldn't.

In view of the above-mentioned circumstances, it is an object of the present invention to provide a method for suppressing the generation of dioxins when municipal waste, industrial waste, etc. are incinerated in a waste incinerator.

[Means for solving problems] In order to achieve the above object, the method for suppressing the generation of dioxin in a waste incinerator according to the present invention
Three or more secondary air supply nozzles whose tips are oriented in the tangential direction of one horizontal imaginary circle are provided on the peripheral wall of the secondary combustion chamber, and these nozzles are used to supply air to the horizontal imaginary circle within the secondary combustion chamber. It is characterized by supplying secondary air toward the contact point.

[Function] In the method for suppressing dioxin generation in a garbage incinerator according to the present invention, the primary combustion gas and secondary air are mixed more completely in the secondary combustion chamber, so the secondary combustion efficiency is improved. Unburnt content is significantly reduced. Therefore, the amount of dioxin precursors contained in the unburned substances is also significantly reduced, the generation of dioxin is prevented, and exhaust gas that does not contain dioxin is released into the atmosphere. Furthermore, the reduction in unburned content also provides the effect of suppressing NOx generation.

[Example] Next, the present invention will be specifically explained with reference to the illustrated example.

FIGS. 1 and 2 show a waste incinerator in which the method for suppressing dioxin generation according to the present invention is implemented. In the same figure, on the peripheral wall (2a) of the secondary combustion chamber (2) of the garbage incinerator,
Four secondary air supply nozzles (10) are provided whose tip outlets are oriented in the tangential direction of one horizontal imaginary circle (C). The tip of the secondary air supply nozzle (10) is located on each side of a horizontal imaginary square (S) centered on the center of a horizontal imaginary circle (C). Assuming that the length of one side of the horizontal imaginary square (S) is D and the diameter of the horizontal imaginary circle (C) is D, the ratio L/D thereof is preferably within the range of 5 to 15.

In such a configuration, in the primary combustion chamber (1),
The garbage (R) placed on the grate (7)
7) is combusted using primary air supplied from below. Combustion gas generated by this primary combustion enters the secondary combustion chamber (2). At this time, the secondary air supply nozzle (lO)
According to the above horizontal virtual circle (C) in the secondary combustion chamber (2)
Supply secondary air towards the contacts. Then, secondary combustion is performed in a state where combustion gas and secondary air are ideally mixed, improving secondary combustion efficiency and significantly reducing unburned matter. Therefore, the amount of dioxin precursors contained in the unburned substances is also significantly reduced, the generation of dioxin is prevented, and exhaust gas that does not contain dioxin is released into the atmosphere. Also, by reducing unburned content, N.

The effect of suppressing the generation of X can also be obtained. Furthermore, since the combustion gas of the primary combustion and the secondary air are ideally mixed, combustion efficiency is improved and the secondary combustion chamber (2) can be made more compact.

specific test Next, specific tests of the method of this invention will be explained.

Using the waste incinerator shown in Figures 1 and 2, we calculated the length of one side of the horizontal imaginary square (S) of the secondary combustion chamber (2) of the incinerator and the horizontal imaginary circle (C). Garbage was incinerated while varying the ratio L/D to the diameter, and the amount of unburned matter in the exhaust gas was measured.

For comparison, garbage was incinerated using a conventional garbage incinerator shown in FIG. 4, and the amount of unburned matter in the exhaust gas was measured.

These results are summarized in Figure 3.

As is clear from these results, in the method of the present invention, the amount of unburned matter is clearly reduced compared to the method using a conventional incinerator.

In the above embodiment, the tip of the secondary air supply nozzle (10) is located on each side of the horizontal board square (S) existing in the secondary combustion chamber (2), but this is not limited to this. If the circumferential wall of the secondary combustion chamber (2) has a square horizontal cross section, the horizontal planar square (S) coincides with the circumferential wall (2a), and the tip of the nozzle (lO) lies on the circumferential wall (2a). 2a) may be opened.

[Effects of the Invention] According to the method for suppressing dioxin generation of the present invention, it is possible to reduce unburned substances containing dioxin precursors. As a result, it is possible to prevent the generation of dioxin and to release exhaust gas that does not contain dioxin into the atmosphere. Moreover, by reducing unburned matter, N
The effect of suppressing ox generation can also be obtained. Furthermore, since the combustion gas of the primary combustion and the secondary air are ideally mixed, the combustion efficiency is improved and the secondary combustion chamber can be made more compact.

[Brief explanation of drawings]

Figure 1 is a vertical sectional view showing the configuration of a waste incineration path for carrying out the method of the present invention, Figure 2 is a cross-sectional view taken along the line ■-■ in Figure 1, and Figure 3 shows the results of specific tests. The graph, FIG. 4, is a vertical sectional view showing a conventional garbage incinerator. (2)... Secondary combustion chamber, (2a)... Peripheral wall, (10
)...Secondary air supply nozzle, (C)...Horizontal virtual circle, (R)...Garbage. More glances ('／・)m

Claims (1)

[Claims] Three or more secondary air supply nozzles whose tips are oriented in the tangential direction of one horizontal imaginary circle are installed on the peripheral wall of the secondary combustion chamber of the garbage incinerator, and these nozzles A method for suppressing dioxin generation in a garbage incinerator, comprising supplying secondary air toward a contact point of the horizontal virtual circle.