JPS6032762B2 - How to operate an incinerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of operating an incinerator, such as a waste incinerator, for suppressed combustion of nitrogen oxides (N○x).

Conventional methods for removing nitrogen oxides from the exhaust gas of incinerators include the denitrification method and the nitrogen oxide suppression combustion method, but measures for denitrification equipment in incinerators are technically difficult in both cases. Another drawback is that both construction and operating costs are very high.

An object of the present invention is to suppress the production of nitrogen oxides by improving the combustion technology of the incinerator, and to provide an easy-to-operate and economical method of operating an incinerator for nitrogen oxide-suppressing combustion.

In an incinerator, such as a waste incinerator, a series of processes occur simultaneously in parallel: drying of the incinerated material, such as garbage, evaporation and thermal decomposition of organic matter, flame combustion, and char combustion.

The lower limit of combustion temperature is limited to a temperature that does not leave any foul-smelling substances in the exhaust gas, and the upper limit is limited to a temperature that does not melt ash.
The temperature conditions are 00 to 1000 qC. The usual method of incineration in conventional incinerators has been to maintain the above-mentioned temperature conditions while completing combustion as quickly as possible.

That is, a method has been adopted in which the gas produced by evaporation or thermal decomposition of organic matter is immediately combusted.

The NOx suppression combustion method according to the present invention divides the so-called drying and combustion stages into the following three stages, and utilizes the effect of suppressing the production of N○x by ammonia etc. generated from the incinerated material. The purpose is to suppress the additional generation of N○× in the combustion furnace. 'i) In the first stage, organic matter is thermally decomposed and turned into combustible gas.

At this time, the nitrogen content in the organic matter generates ammonia and organic nitrogen radicals. 'ii} In the second stage, sufficient residence time is given to the pyrolysis gas to decompose part of the nitrogen content in the organic matter into nitrogen molecules (N2) and stabilize it. At this time, if NO is spread due to other sources such as oil combustion, it is reduced to stable N2 by reacting with ammonia or the like. Tsuyoshi: In the third stage, the air for secondary combustion is newly supplied to multiple locations in the secondary combustion chamber to suppress the extreme rise in fire temperature.
This is to ensure complete combustion of flammable gas while preventing additional generation of combustible gas.

That is, the present invention provides an incinerator that includes a drying stoker, a combustion stoker group, and a post-combustion stoker group, and adjusts the driving speed of each stoker group according to the amount of material to be incinerated, and supplies air to the drying stoker group. By reducing the amount, the material to be incinerated is partially thermally decomposed, and the ammonia generates reducing gases such as hydrogen cyanide.On the other hand, by supplying sufficient air to the combustion stoker group and the post-combustion stoker group, combustion is accelerated. The combustion gas containing nitrogen oxides generated here is reacted with the reducing gas generated above to reduce the nitrogen oxides to nitrogen, and the dry stoker group, combustion stoker group, and after-combustion stoker group This is a combustion furnace operating method in which the required amount of air is supplied from multiple locations in the secondary combustion chamber when the combustion of unreacted gas is completed. Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a schematic flow sheet of one embodiment showing the method of operating the incinerator used in the present invention, in which the materials to be incinerated, garbage 1, put into the incinerator are divided into groups of dry stokers 2 in the direction of flow. , 3, combustion stoker groups 4, 5, 6, and post-combustion stoker groups 7, 8, and are incinerated while being sequentially sent thereto. At this time, the primary air sent from the blower 9 is distributed to each stoker as follows. That is, the dry stoker air damper 10
, 1 1 and the upper stage combustion stoker air damper 12 are throttled to suppress the amount of air supplied, a reducing atmosphere is created by partial combustion thermal decomposition, and flammable gas, ammonia, and organic nitrogen radicals are generated.

As described above, an important point of the present invention in achieving the object of the present invention is to reduce the amount of air supplied to the drying stoker group to generate reducing gas.
On the other hand, the remaining combustion stoker air dampers 13, 14 and post-combustion stoker air dampers 15, 16 are opened to supply sufficient air to complete the combustion of the materials to be incinerated and the char. In order to carry out the above combustion smoothly, each stoker drive device 17, 18, 19, 20, 21, 22, 23
The feed speed of each stoker is arbitrarily adjusted automatically or manually to control the thickness of the layer of the material to be incinerated on each stoker to an appropriate amount.

The thickness of the layer of these materials to be incinerated varies depending on the composition and moisture content of the materials to be incinerated, but on a dry stoker group, the thickness is 400 to 80.
0 side, 180 to 600 ribs on the combustion stoker group, and 100 to 200 sides on the post combustion stoker group are suitable.

By doing the above, the combustion gas containing NOx mainly generated at the rear of the combustion stage and the post-combustion stage is mixed with the pyrolysis gas generated at the drying stage and the front of the combustion stage, and the NOx
reacts with ammonia etc. and is reduced to stable N2. Furthermore, when completing the combustion of the uncombusted gas in the secondary combustion scale chamber 24, the secondary air sent from the blower 25 is transferred to the air inlet 29 by a plurality of dampers, for example, 26, 27, and 28.
, 30, and 31 to suppress the extreme rise in fire temperature and prevent additional generation of NOx.

Next, the present invention will be explained by examples.

EXAMPLE The incinerator used in the present invention was operated according to the operating conditions shown in Table 1 using materials to be incinerated (garbage) having the following composition.

An example of measuring N○k in this case is shown in FIG. Example of garbage composition Combustible content 41.8% Lower calorific value ash 12.0% 1800Kcaso/k9
An example of operating conditions with a moisture content of 46.2% is shown in Table 1.

Table 1 Note: The numbers in parentheses in item 5 indicate the respective primary air excess ratio calculated from the air excess ratio.

FIG. 2 shows an example of the measured values of N○× at the outlet of the secondary combustion chamber when an incinerator, such as a waste incinerator, is operated according to the above embodiment.

In Example (A) of the method of the present invention, there were approximately 150 to 200 N○×, which decreased by approximately 10 pm' after implementation (B). Note that FIG. 3 is attached as an example showing the effects of the present invention.

Figure 3 shows dry stoker groups 2 and 3 and combustion stoker 4.
This shows the amount of air supplied to the drying stoker group [excess air ratio (input)] and the measured value (ppm) of N○× at the outlet of the secondary combustion chamber.
The amount of Ok produced is decreasing.

As explained in detail above, the reducing gas such as ammonia produced in the combustion gas of the incinerator according to the present invention is
Since this can be reduced to stable N2 by reacting with N2, it has become possible to realize an easy-to-work and economical N○x suppression combustion operation method.

[Brief explanation of the drawing]

FIG. 1 is a schematic flow sheet of an embodiment of an incinerator used to explain the present invention, and FIG. 2 is an example of measurement of N○k in this embodiment. Figure 3 shows the excess air supply rate (in) to dry stoker groups 2 and 3 and combustion stoker group 4 and the N○k concentration at the outlet of the secondary combustion chamber (
skin). 1...Things to be incinerated, 2,3
...Dry stalker group, 4, 5, 6...
Combustion stoker group, 7, 8... Post-combustion stoker group, 9
...Primary air blower, 10, 11, 12, 13
, 14, 15, 16... Air damper for each stoker, 17
, 18, 19, 20, 21, 22, 23... each stoker drive device, 24... secondary combustion chamber, 25...
...Secondary air blower, 26,27,28...Secondary air damper, 29,30,31...Secondary air inlet, (A)...Book Concentration of nitrogen oxides in the conventional operation example of the embodiment of the invention, (B) Concentration of nitrogen oxides in the embodiment of the invention. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. In an incinerator equipped with a drying stoker group, a combustion stoker group, a post-combustion stoker group, and a secondary combustion chamber, the driving speed of each stoker group is adjusted according to the amount of material to be incinerated, and the air flow to the drying stoker group is adjusted. By restricting the supply of air, the material to be incinerated is partially thermally decomposed and reducing gases such as ammonia and hydrogen cyanide are generated, while by supplying sufficient air to the combustion stoker group and the post-combustion stoker group. , the combustion is completed, and the combustion gas containing nitrogen oxides generated here is reacted with the reducing gas generated above to reduce the nitrogen oxides to nitrogen, and the dry stoker group, combustion stoker group, and after-combustion are A method of operating an incinerator characterized by supplying a necessary amount of air from a plurality of locations in a secondary combustion chamber when completing combustion of unreacted gas generated in a stoker group.