JPS60156921A - Denitrating method of exhaust gas in prime mover - Google Patents

Abstract

PURPOSE:To make exhaust gas denitrateable without using a denitrater catalyzer, by leading the exhaust gas into a burner air box of a boiler furnace and, after being burned, making it into combustion with a reducing atmosphere upon adding fuel, then successively burning it slowly with air added. CONSTITUTION:Exhast gas out of a prime mover 20 is led into a burner air box 25 of a boiler 22 and a furnace 23, then mixed with primary fuel 29a and made into a primary combustion A inside the furnace 23. And, secondary fuel 29b alone is fed to a slipstream range of a primary combustion range and made into a secondary combustion B as a case that a reducing atmosphere is lack of oxigen. Next, combustion air 37 in the amount required to burn an unburned portion left over at the secondary combustion is fed to a spot nearby the secondary combustion range, thus a slow-going tertiary combustion C takes place.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an exhaust gas denitrification method for a prime mover, which denitrates combustion exhaust gas discharged from a prime mover such as a diesel engine or a gas turbine.

Conventional configuration and its problems The combustion exhaust gas emitted from IJXD machines such as diesel engines and gas turbines contains large amounts of nitrogen oxides (hereinafter referred to as NOx) generated during fuel combustion9.
In particular, when used on land, it is necessary to perform a large amount of denitrification due to the restriction that the NOx value is the same as that of a boiler, and research is underway on methods of denitrifying exhaust gas using denitrification catalysts.

FIG. 1 shows a conventional method for denitrating exhaust gas from a diesel engine. That is, (υ is a diesel engine linked to the generator (2), and this diesel engine (
The exhaust gas from 1) flows through the exhaust gas duct (3) into the exhaust gas denitrification device (4), is denitrified while passing through the denitrification catalyst (5) in this exhaust gas denitrification device (4), and is denitrified while passing through the exhaust gas boiler, ( 6) to the chimney (7).

According to this conventional method, a special feature of the diesel engine (1) is that unburned fuel oil, lubricating oil, etc.
adheres to and has a negative effect. In addition, the catalyst layer has not yet been put into practical use because there are many research issues, such as the need for a catalyst with low resistance as the output of the diesel engine decreases due to an increase in the exhaust pressure of υ.

FIG. 742 shows a conventional exhaust gas denitrification method for a gas turbine. In other words, uCJ is a gas turbine linked to generator u〃, and the exhaust gas from this gas turbine passes through the exhaust gas duct @ and flows into the exhaust gas denitrification equipment i (to), and the exhaust gas inside this exhaust gas denitrification equipment (to) It is denitrified while passing through the denitrification catalyst 4, and then flows to the chimney 0υ. The Iroki exhaust gas denitrification device constitutes a part of the exhaust gas boiler 4, and the heat transfer system installed inside it communicates with the boiler dome Q barrel.

According to this conventional method, it is necessary to equip the exhaust gas denitrification device tu3 with a large amount of denitrification catalyst u4) in the reactor.
Therefore, the reduction in output due to the increase in exhaust pressure of gas turbine 4 is compensated for. In addition, for denitrification, a dry selective catalytic reduction cracking method using ammonia is mainly used. There are many problems such as replacement due to deterioration of the catalyst, and on top of that, the initial cost and maintenance cost are 4 +%.
arrive.

OBJECTS OF THE INVENTION An object of the present invention is to provide a method for denitrating exhaust gas from yi and wj machines, which can denitrate exhaust gas without using a denitrification catalyst.

Structure of the Invention In order to achieve the above object, the present invention provides a method for denitrifying exhaust gas from a prime mover. Only the secondary fuel is supplied to the downstream area of the primary combustion zone formed by the process to create a reducing atmosphere lacking in oxygen for secondary combustion, and then the unburnt material remaining from the secondary combustion is burned near the secondary combustion zone. This system supplies the necessary amount of combustion air to perform slow tertiary combustion.

Embodiments and Effects Embodiments of the present invention will be described below with reference to FIGS. 3 and 4.

FIG. 3 shows a method for denitrating exhaust gas from a diesel engine, which is an embodiment of the present invention. In other words, ■ is the generator 12
Diesel engine (an example of a prime mover) linked to υ, (2
) is a boiler consisting of a furnace frame, boiler drum (to), wind box (ho), etc. 14il recording diesel engine (
A) and the wind box ■ communicate with each other via an exhaust pipe (A), and a third edamba (B) is provided at the end of the exhaust pipe (E). The wind box (7) is housed in the front part of the furnace q, and the exhaust pipe (g) communicates with the upper part of the wind box (7). In addition, the main burner (to) facing the rear is located in the center of the wind box (to),
−m of boiler fuel (A) for this main burner (E)
(29a)=& is available for supply. A secondary burner (7) is arranged at the middle upper part of the furnace frame so as to face the downstream area of the primary combustion M (main combustion [)] formed by the primary combustion on the main burner (E) side. Secondary fuel (29b), which is boiler fuel, can be supplied to the secondary burner (29b). A rear heat transfer surface Cil+ is provided at the rear of the hole l175-.
6d is installed, and the outlet of this rear heat transfer surface 611 is the chimney cl
connected to power. The connection is a forced feeder 111a, the terminal end of which is connected to the section of the wind box, and a second damper (1d) is installed near the terminal end. A branch blow pipe side communicates with the middle of the air blow pipe ¥1f341, and the terminal end of this branch blow pipe □□□ communicates with a two-stage air supply port η provided at the rear of the furnace. - is the third damper installed in the branch air pipe side, and ) is the secondary combustion area (reduction combustion JJE)
, fcl indicates tertiary combustion [(complete combustion region).

The effects of the above embodiment will be explained below. The exhaust gas from the diesel engine (a) contains, for example, about 1200 ppm of NOx. But o2 is about 1
The gas temperature is about 400"C and can be used as is as fuel combustion air for the boiler (E).Therefore, the exhaust gas from the diesel engine 4 is transferred to the exhaust pipe (E). The exhaust gas is led to the wind box through the furnace, and the entire amount of this exhaust gas is used as boiler fuel combustion air and combusted together with the fuel.

On the other hand, the boiler fuel is supplied separately into secondary fuel (29a) and secondary fuel (29b). - The secondary fuel (29a) is supplied to the main burner (29a), mixed with the exhaust gas from the diesel engine (a) and subjected to primary combustion, thereby forming a primary combustion zone. At this time, the second damper 4 is closed,
For combustion from the ventilation control side! ! ! Qi is not supplied.

Next, the secondary burner (7) is installed toward the downstream area of the primary combustion zone.
Only the secondary fuel (29b) is injected from the secondary combustion zone (Bl) and combusted in a reducing atmosphere lacking oxygen to form the secondary combustion fuel (131).
Therefore, even if new NOx generation due to fire combustion is added, large to medium low NOx
It is possible to measure the Furthermore, in the secondary combustion*fB+, the fresh air necessary for burning the unburned matter that could not be burned in fB+ is supplied into the furnace @ through the second stage air supply port 3η by the forced air blower l33), resulting in slow tertiary combustion. Combustion is performed to form a tertiary combustion zone tc).

As mentioned above, tertiary combustion is slow, so NOx
Combustion will be completed while suppressing re-occurrence. The exhaust gas with reduced NOx in this way is sent to the boiler (a).
The heat is sufficiently recovered at the rear heat transfer surface (boiler contact heat transfer surface, economizer, gas air heater, etc.) 31), and then led to the chimney and discharged.

In addition, when the boiler 4 is operated independently, the first damper (b) is closed and the second damper 3FG is opened to supply combustion air from the forced blower to the wind box (b).

According to the method of the embodiment described above, it is possible to effectively utilize the energy of the high temperature and high air ratio exhaust gas discharged from the diesel engine, and also to reduce the amount of exhaust gas from the diesel engine without using an expensive exhaust gas denitrification device. The NOx value of approximately rz00ppm (02:12. released into carved cedar) is compared to the NOx value of boiler exhaust gas (150 to 250ppm).
It can be reduced to a certain extent. If an even greater reduction in NOx is required, it is sufficient to install the boiler exhaust gas denitrification device ft1, which uses a denitrification catalyst that has already been put into practical use, at the optimal point of the boiler outlet gas. This means that there is no need to consider the inconveniences that would occur if the device were installed directly into the exhaust gas.

FIG. 4 shows a method for denitrating exhaust gas from a gas turbine, which is another embodiment of the present invention. The only difference from the previous embodiment is that a gas turbine is used as the prime mover, and the rest are the same or almost the same.

According to this embodiment, without using expensive exhaust gas denitrification equipment, - for example, about 4
N04t of 00-500pprn (02:4% conversion)
, the NOx value of boiler exhaust gas can be reduced to about 150 to 200 ppm.

Effects of the Invention According to the present invention having the above configuration, the following effects can be expected.

0 The NOx value of exhaust gas emitted from a prime mover such as a diesel engine or gas turbine can be reduced to about the NOx value of boiler exhaust gas without using an expensive and problematic exhaust gas denitrification device.

Thermal energy contained in the exhaust gas from the O prime mover can be recovered at the po-ira, and there is no loss.

When using a forced air blower for an O-boiler, it is only necessary to operate it at full power only when the boiler is operating alone, and in normal cases it is only necessary to operate it at a small output to send air for tertiary combustion.

[Brief explanation of the drawing]

Figure 1 and Figure 2 show conventional examples, Figure 1 is a schematic diagram of the diesel engine exhaust gas denitrification method, Figure 2 is a schematic diagram of the gas turbine exhaust gas denitration equipment, Figures 3 and 4. FIG. 3 is a schematic diagram of a diesel engine exhaust gas denitration method, and FIG. 4 is a schematic diagram of a gas turbine exhaust gas denitration method. (E)°°“Diesel engine (IjXI4JJ machine)
, □□□... Boiler, Threat - Furnace, (To)... Boiler drum, 4... Wind box, (7)... Exhaust pipe, (Support)... Main burner, ( 29a)...-Next fuel, (29
b)...Secondary fuel,...-Secondary burner, Eel...Forced blower, i3'6...Second air supply port, 139)
...Gas turbine (prime mover), prisoner...-Next combustion composition, 0
3)...Secondary combustion area, (C)...Tertiary combustion area agent Yoshihiro Morimoto

Claims (1)

[Claims] 1. Exhaust gas from the prime mover is led to the burner wind box of the boiler furnace, mixed with secondary fuel, and primary combusted in the furnace, thereby supplying only secondary fuel to the downstream area of the primary combustion area formed. to perform secondary combustion in an oxygen-deficient reducing atmosphere, and then supply a pan of combustion air necessary for burning the unburned matter remaining in the secondary combustion near the secondary combustion zone,
g! A method for denitrifying exhaust gas from a prime mover, which is characterized by slow tertiary combustion.