JPS58200909A - Combustion method for decreasing nitrogen oxide - Google Patents

Abstract

PURPOSE:To promote combustion of unburning combustion gas generated from main burners and a planet burner, by a method wherein primary gas is supplied to an after-air port, and the force of penetration of the after-air is reinforced to sufficiently mix together combustion air and the after-air. CONSTITUTION:The force of penetration of a jet air from an after-air port 5 is reinforced such that, according to an unburning gas reducing signal from a combustion condition monitor 14, mounted to an outlet of a boiler, a quantity of a primary gas for reinforcing the force of penetration is regulated by a primary gas regulating valve 15 installed on a primary gas line 11 to supply it to a primary gas nozzle 13, and gas 12 is jetted into a furnace as it is accompanied with an after-air 10. This increases the force of penetration of the jet air from the after-air port which commits a perfect combustion of unburning exhaust gas generated in a main burner and a planet burner range, and enables the perfect combustion. Further, this enables to perform a combustion with less unburning exhaust gas, which results in the reduction in the production of NOX also.

Description

Detailed Description of the Invention The present invention relates to a combustion method for reducing nitrogen oxides, and in particular to a multi-burner combustion method suitable for reducing nitrogen oxides (hereinafter referred to as NO) in exhaust gas. A so-called multi-burner combustion method is an effective dog-sniffing method for reducing NO contained in exhaust gases. In this method, a stone complete combustion zone, a gas phase reduction zone, and a complete combustion zone are sequentially formed in the gas flow direction from the upstream side of the combustion zone in the furnace.

Conventionally, in the multi-burner combustion method described above, control of the air-fuel ratio of each stage burner was considered to be an important factor in achieving the reduction reaction1, and it was necessary to operate it within an appropriate range. The system diagram of this conventional combustion system is shown in Figure 1.The operating conditions of each burner were exactly the same except for the air-fuel ratio.

The figure shows a combustion system for a boiler that performs front firing.From the lower position on the front surface 112 of the furnace 1, there are the main burner 3 that forms a complete combustion zone, and the planet that forms a gas phase reduction zone. A burner 4 and an after air port 5 forming a complete combustion zone are provided, each burner 3.
4 and after-air port 5 are connected with a fuel supply line 6, a combustion air line 7, and an exhaust gas circulation line 8. Note that 21 and 22 are circulation fans, and 23 and 2 are regulating valves.

In this way, in electrical manufacturing, NO, reduced combustion (・/'
t, fuel is supplied almost equally to each stage burner, and combustion air is supplied to the regulating valve 9 at the burner inlet, with an air-fuel ratio of 0.9 to 1.0 for the main burner and 0 for the planet burner.
．． The air amount is adjusted to 4 to 0.5 and is supplied to the burner,
The remainder is supplied to the after air port 5. In this way, even if combustion occurs at an air-fuel ratio of 11 or less than the stoichiometric air position, which is below the planet burner position, unburned gas is inevitably generated, but this unburned gas is combusted at the after air port 5.

However, in the conventional combustion system, the kinetic energy of the burner jet overcomes the energy of the upward flow velocity in the lowest stage burner, where the upward flow rate of the gas in the furnace is the slowest, and the holes penetrate to the depths of the burners in each stage. 1) Does the furnace rise as the burner stage moves to E? As the N and velocity increase, the kinetic energy of the burner jet becomes small compared to the rising kinetic energy, and the mixing of the in-furnace gas flow and the after air 10 is poor, which causes the generation of unburned matter. I found out that there is. Note that 20 air registers are shown in Figure 1. Also, due to the generation of unburned matter, a sufficient NO! Unable to maintain the air-fuel ratio of each burner required for reduction,
It was found that this also caused the NO reduction effect to be halved and the regeneration Now to occur.

The purpose of the present invention is to eliminate such drawbacks of the prior art,
An object of the present invention is to provide a combustion method capable of reducing nitrogen oxides without increasing unburned components (soot and dust) in exhaust gas.

The present invention was developed in view of the fact that the penetration force of the after-air port greatly affects the complete combustion of unburned gas. A part of the gas nozzle and a part of the gas supply line are installed to promote the mixing of combustion gas in the furnace and after air to achieve complete combustion.

D, which uses a part of the combustion exhaust gas of the combustion device, is convenient as the secondary gas.

An embodiment of the present invention will be described below with reference to the drawings.

Figure 4 shows a boiler system using the front-firing type 4'', with the front furnace 111k2 of the furnace l,
From the lower position, the main burner 3, the fuel nozzle i and the rctor abort 5 are connected, and the supply of combustion air and exhaust gas to each nozzle is carried out by the fuel j()6, combustion Through the air line 7 and the exhaust gas circulation line 8 [2] The procedure is the same as the method shown in FIG. A valve 15 is provided, and a control device is provided in the combustion condition monitoring device No. 1 provided in the boiler exhaust gas flow path to monitor the generation status of unburned matter and to open and close part of the gas flow lid regulating valve 15 depending on the situation. The difference is that

In the apparatus having the E period configuration, the air-fuel ratio of each stage and gunner is adjusted to the Tovana air-fuel ratio O9 to O05, and the remaining combustion air is blown into the furnace from the after air port 5. On the other hand, the penetration force of the air ejected from the after air port 5 is increased by the unburned gas reduction signal from the combustion state monitoring device 14 installed at the boiler outlet, and the partial gas regulating valve 15 installed in the secondary gas line 11 is used to strengthen the penetration force. The amount of gas 12 is adjusted and supplied to the partial gas nozzle 13 shown in FIG.
It is ejected into the furnace while entraining it.

As mentioned in E, the present invention reverses the distribution of the penetration force of the after air ejected from the lid air port 5 compared to the conventional one, and increases the penetration force in the furnace compared to other burners in accordance with the situation of unburned matter generation. Efforts are being made to improve the mixing in the papermaking and furnace. Therefore, the penetration force of the after air port to completely burn the unburned matter generated in the main burner and the net top burner increases, and the sixth
As shown in the figure, since a good mixture of in-furnace combustion gas and after air is obtained, there is no imbalance in the concentration of unburned matter, and complete combustion is possible. On the other hand, since combustion with a small amount of unburned matter becomes possible, NO reduction combustion can also be carried out effectively.

In the above embodiments, the combustion state monitoring device i14 can be a device for detecting the combustion state in the furnace, such as a device for detecting unburned components in exhaust gas, a device for directly observing the fire state in the furnace, etc. .

As described above, according to the present invention, by supplying some gas to the after air port, the penetration force of the after air is strengthened, the combustion gas and the after air are sufficiently mixed, and the residual gas generated from the main burner and the planet burner is The combustion of fuel can be promoted.

[Brief explanation of drawings]

Figure 1 is a system diagram of a conventional front-firing combustion system, and Figure 2 is a structural diagram of a conventional after-airport area. Figure 3 is a diagram showing a fire pattern in the furnace of a conventional multi-burner combustion method. , FIG. 4 is a system diagram of the combustion device according to the present invention, FIG. 5 is a structural diagram of the vicinity of the after air boat according to the present invention, and FIG. 6 is a diagram showing the fire pattern in the furnace of the multi-burner combustion method according to the present invention. be. ]...Furnace, 2...Front wall, 3...
Main burner. Number: Planet Burna, 5... After Airport,
6...Fuel line, 7...-Combustion air line,
8... Exhaust gas line, 9... Regulating valve,
10... After air, 11... Primary gas line, 12... Primary gas, 13...-- 1
Next gas nozzle, 14... combustion. Condition monitoring device, 15...Primary gas regulating valve. Agent Patent Attorney Takenaga Kawakita

Claims (1)

[Claims] (1) In the combustion method for reducing nitrogen oxides in exhaust gas, a complete combustion zone is created in the combustion chamber by forming a complete combustion zone, a gas phase reduction zone, and a complete combustion zone in the exhaust gas flow direction. A nitrogen oxide reduction combustion method characterized by supplying primary gas to an air port and making the penetration force into the furnace greater than that of the other stages. (2. In claim 1, the nitrogen oxide gas is supplied from the exhaust gas supply main pipe to the primary gas line and the flow regulating valve'!!: to the after air port. Reduction combustion method, (3) In claim 1, the combustion control arm signal of the furnace internal combustion!18 condition monitoring device (by operating the -7 gas flow rate adjustment valve, A special combustion method for reducing nitrogen oxides that controls the penetration force of after-air by adjusting the amount of after-gas.