JPS5938521A - Incinerating disposal method for gas containing nitrogenated chemical compound - Google Patents

Abstract

PURPOSE:To minimize the total amount of NOX produced, by a method wherein, through control of the temperature of a primary combustion part to 900-1,050 deg.C, the amount of NOX initially produced is sharply reduced, and the temperature of a secondary combustion part is also controlled within said temperature range. CONSTITUTION:A combustion furnace is devided into a primary combustion part for front half and a secondary combustion part for rear half, and the primary combustion part is controlled to 900-1,050 deg.C through the use of an auxiliary burner and/or introduction of combustion exhaust gas with temperature of 100-500 deg.C. It is desirable that the air to the primary cmbustion part is introduced through the auxiliary burner or parallel to gas containing nitrogenated chemical compound. The air ratio of the primary combustion part is controlled to lower than 1 through control of the amount of the introduced air and combustion exhaust gas. Said operation causes the gas at the outlet of the primary combustion part to produce NOX of tensmm. and the gas with temperature of 900-1,050 deg.C having the remaining gas containing nitrogenated chemical compound or pyrolysis gas thereof, the gas flowing in the following secondary combustion part. Also in the secondary combustion part, combustion of remaining unburnt gas is effected in a way that combustion exhaust gas with temperature of 100-500 deg.C is introduced to control it to 900-1,050 deg.C, and this enables reduction of the production of NOX at the furnace outlet.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for incinerating a gas containing a nitrogen-containing compound, and more particularly to a method for incinerating a gas containing a nitrogen-containing compound to suppress the production of nitrogen oxides.

Gases containing nitrogen-containing compounds cannot be released directly into the atmosphere for pollution control reasons, so they are generally incinerated. At that time, the generation of nitrogen oxides (hereinafter referred to as NOx) becomes a problem (in particular, the recent total NOx regulation requires a value of 3.50 pc or less, which is even lower than the NOx 25op of the conventional incinerator exhaust gas regulation). In some cases)
, an incineration process that produces as little NOx as possible is desired.

Conventional low NOx combustion methods for gases containing nitrogen-containing compounds (amines, dilyls, hydrogen cyanides, etc.) include:
There is a two-stage combustion method in which the nitrogen-containing compound-containing gas is firstly combusted at an air ratio of 1 or less, and then secondary air is added and the gas is combusted twice.

However, in this method, even if the nitrogen-containing compound-containing gas is combusted in the -fire combustion section at an air ratio of 1 or less, the
1. - The temperature of the part becomes high lr'/i: Initial NOx
There is a problem that a large number of .

In view of the above, an object of the present invention is to provide a method for combustion treatment of nitrogen-containing compound-containing gas, which can reduce the initial amount of NOx produced and minimize the overall amount of NOx produced.

The inventor investigated the cause of NOx generation in the above primary combustion section and found that (1) the average air ratio of the primary combustion section is 1
This is due to the following two points: (2) there are localized areas where the air ratio is higher than 1 even if the air ratio is below 1, and (2) the flame part of the primary combustion section reaches a high temperature of 1200°C or higher. I understand. That is, FIGS. 1 and 2 show 5 v
02% N2 balance gas is supplied with air 1.1 times and 1.2 times the theoretical air volume, and the temperature is approximately 800 to 1400℃.
NO when oxidized at a temperature of 0.5 seconds and a reaction time of 0.5 seconds.
It shows the change in x concentration. In the figure, l indicates the case where the air ratio is 1.1, and 2 indicates the case where the air ratio is 1.2. The figure shows that the temperature dependence of NOx production is extremely large.
Especially when the temperature rises above about 1200℃, NOx increases by 500℃.
Figure 3 shows that the hydrogen cyanide concentration is 2%, and the oxygen concentration is 5% and 2.8, respectively.
% (each item %) and residual N are oxidized in an electric furnace at a temperature of about 800 to 1500°C and a reaction time of 0.5 seconds, showing a change in NOX of 9 degrees. However, in this case as well, the temperature dependence of NOx production is extremely large, especially when the temperature exceeds about 1200'l), it was found that NOx becomes strained to a value 1' of 5001- or more.

Furthermore, from the results shown in Figure 1 (not shown in Figure 7) and Figure 3, NOx generation in the oxidation of a gas containing an air-containing compound is approximately QQ○ ~ 10
A peculiar phenomenon was discovered in which the temperature decreases sharply in the range of 50℃.
Ta. Part 1. It was found that the oxygen concentration is less than a few percent, and even if oxygen is present, NOx will be less than 1(,) Up. Therefore, the temperature of the primary combustion section should be set at 900 to 1050.
℃ and the average air ratio is 1 or less, the initial NOx ff:1 even if there are local areas where the air ratio is 1 or more.
It was found that it could be suppressed to 0 to 20 pp+.

The present invention has been made based on the above findings regarding low air ratio combustion of nitrogen-containing compound-containing gas.

In this method, a gas containing nitrogenous compounds is introduced into the secondary combustion zone to perform an oxidation reaction, and then introduced into the secondary combustion zone to combust the remaining unburned materials. The nitrogen-containing compound-containing gas to be treated by the present invention is characterized in that the temperature is controlled at 900°C to 050°C with the use of auxiliary fuel and/or the introduction of combustion exhaust gas. is a gas containing at least one compound selected from amines, nitriles, and hydrogen cyanide.

In the present invention, the combustion furnace is divided into a primary combustion section in the first half and a secondary combustion section in the latter half. Configure as a separate furnace! , 7, it goes without saying that the primary combustion section t, the use of an auxiliary burner and/or the use of 100~5
900-1050℃ by introducing combustion exhaust gas at 00℃
controlled by. Note that the auxiliary burner only needs to have a capacity greater than that of the pilot burner. The nitrogen-containing compound-containing gas is usually introduced into the primary combustion section from a separate nozzle from that of the air.
As for the introduction method, it is preferable to introduce the nitrogen-containing compound-containing gas parallel to the auxiliary burner or tangentially outside the frame so that the nitrogen-containing compound-containing gas does not penetrate into the frame formed by the auxiliary burner. The air to the primary combustion section is preferably introduced through an auxiliary burner or in parallel with the nitrogen-containing compound-containing gas.

The air ratio in the primary combustion section is controlled to 1 or less by adjusting the amounts of introduced air and combustion exhaust gas.

With the above operations, the log gas coming out of the primary combustion section will be several tens of NO.
x and the remaining unburned nitrogen-containing compound-containing gas or its thermal decomposition gas at a temperature of 900 to 1050°C, which flows into the downstream secondary combustion section.

Next, in the secondary combustion section, the combustion of the remaining unburned gas is
Introducing combustion exhaust gas of 100-500℃
The temperature is controlled at 50°C to reduce NOx at the furnace outlet.

In addition, in the present invention, in addition to the method of introducing combustion exhaust gas, other methods such as water spraying can be considered to adjust the temperature inside the furnace, but the point is to equalize the oxygen P degree in the furnace. Flue gas is most preferred.

According to the present invention, in the low air ratio two-stage combustion of a gas containing nine element-containing compounds, the temperature of the primary combustion part is set to 900 to 1050.
．． By controlling the temperature to ℃, the initial NOx production is drastically reduced, and even more preferably, the temperature of the secondary burn area is also controlled within the above temperature range, thereby minimizing the overall NOx production. be able to.

Hereinafter, comparative examples and examples of the present invention will be described, but they are not limited to the present invention. stomach.

Comparative Example 1 was heated to 1000°C by a pilot burner using copropane gas and a rotary burner burning A heavy oil.
Next, a nitrogen-containing red compound-containing gas (acetonitrile (CH
3CN) 10 Vojl '10 Diethylamine ((C4H5)1 N ■■) 5 VolLX,, Sot
v Other N, J420, hydrocarbon water [gas] was introduced in parallel with the pilot burner [7, When primary combustion was performed at Soratsukuda 4 ratio 0.80, even if the rotary cooker was stopped, the inside of the primary furnace remained 1
The temperature was 200°C, the NOx of 1 was 2], and the temperature was OP. When the above gas was introduced into the secondary furnace and secondary air was added to make the air ratio 1.2, the secondary furnace temperature was 140.
The temperature was 0℃, and the NOx level was 450.

Example] In the operation of the above-mentioned tertiary furnace, combustion exhaust gas at :SOO°C was introduced in parallel with nitrogen-containing compound-containing gas, and the temperature inside the furnace was controlled to 1000°C and the air ratio to O, B. The NOx at the outlet of the next furnace was 50-. When the same gas was led to the secondary furnace and secondary air was added to make the air ratio 1.2, the temperature in the secondary furnace was 1150°C, and the secondary furnace outlet N0xi 1
It was 401,411. However, "-3 in rudder operation
00℃ combustion exhaust gas was introduced, and the air ratio of the secondary furnace was 1.2.
When the temperature is controlled at 1000℃, NOx at the secondary furnace outlet
was 55-.

Comparative Example 2 A pilot burner using propane gas and a rotary burner burning heavy oil A were used to heat the paper, and hydrogen cyanide-containing gas (HCN 25% by volume, other N, etc.) (, 0.0, hydrocarbon gas) was introduced in parallel with the pilot burner and primary combustion was performed at an air ratio of 0.85. Even when the rotary burner was stopped, the temperature inside the primary furnace remained at 1250°C.
Therefore, NOx at the primary furnace outlet was 250p. When the above gas was still introduced into the secondary furnace and secondary air was added to make the air ratio 1.2, the secondary furnace temperature became 1350°C.
NOx was 400P. Note that the HCN concentration in the exhaust gas was 1.2-.

Example 2 In the operation of the above primary furnace, combustion set gas at 300°C was introduced in parallel with hydrogen cyanide-containing gas, and the temperature inside the 1st furnace was controlled to 1000°C and the air ratio to 0.85. As a result, NOx at the primary furnace outlet was was 30p. Also, assume that this gas is led to the secondary furnace and secondary air is added to make the air ratio 1.2.The temperature in the secondary furnace is 100℃, and the NOx at the outlet of the secondary furnace is 1.
It was 40F. However, in the above operation, 300℃ flue gas was introduced, the air ratio of the secondary furnace was 1.2, and the temperature was 1.
When controlled at 000℃, the NOx at the outlet of the secondary furnace was 80F.
Met. Note that the HCN concentration in the exhaust gas was 1.7F.

[Brief explanation of the drawing]

Figures 1, 2, and 3 show the experimental results of the electric furnace according to the present invention, and show the relationship between the oxidation reaction temperature of nitrogen-containing compound-containing gas and the NOx concentration after the reaction. FIG. Agent Patent Attorney Takenaga Kawakita

Claims (3)

[Claims] (1) In a method in which a nitrogen-containing compound-containing gas is introduced into the primary combustion section to perform an oxidation reaction, the gas is introduced into the secondary combustion section, and the remaining unburned materials are incinerated. 1. A method for incinerating a nitrogen-containing compound-containing gas, which comprises controlling the ratio to 1 or less and controlling the temperature to 900 to 050°C by using auxiliary fuel and/or introducing combustion exhaust gas. (2) By introducing combustion exhaust gas into the secondary combustion section,
2. The method for incineration of nitrogen-containing compound-containing gas according to claim 1, characterized in that the temperature of the secondary combustion section is controlled to 900 to 1050°C. (3) The method for incinerating a nitrogen-containing compound-containing gas according to claim 1 or 2, wherein the nitrogen-containing compound is at least one selected from amines, nitriles, and hydrogen cyanide.