JPH05332509A - Inter-furnace discharged gas circulation type low nox burner - Google Patents

Abstract

PURPOSE:To improve an effect of low NOx with a normal combustion device by a method wherein a passage extending from a discharged gas feeding passage to a fuel blowing port is formed as a venturi, the inter-furnace discharged gas is sucked with a fuel injection energy, mixed to each other and ignited. CONSTITUTION:A fuel blowing port 22 having a fuel injection nozzle 24 arranged therein is positioned at an outer circumferential part of a combustion chamber 14 and connected to a discharged gas feeding passage 28 opened into a furnace 10. An entire passage extending from the discharged gas feeding passage 28 to the fuel blowing port 22 is formed as a venturi pipe. Then, fuel is injected from the fuel injection nozzle 24, thereby the inter-furnace discharged gas is sucked with the fuel injection energy and fed into a combustion chamber 14 so as to mix and ignite the combustion discharged gas within the furnace 10. Accordingly, it is possible to produce a stable flame while adjusting an amount of feeding combustion air.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to exhaust gas circulation type low NO in a furnace.
_{The present invention} relates to an _X burner, and more particularly to an in-furnace exhaust gas circulation type low NO _X burner suitable for application to a fired furnace using a so-called combustor such as petroleum refining, petrochemicals and boilers.

[0002]

2. Description of the Related Art In burners used in fire furnaces, reducing the emission concentration of nitrogen oxides (NO _x ) in combustion exhaust gas has become a major issue. Conventional low NO _X burner intended incorporating NO _X generation suppression function to the burner itself, generally as achieve NO _X generation suppressed by lowering the lean oxygen concentration combustion flame temperature by high excess air There is.
Therefore, the low NO _X burner or the like which employs a two-stage combustion method also seen, which supplies the high excess air to the outer periphery of the burner flame, the flame center lean by supplying atomization fluid such as steam Conventional techniques have been proposed in which oxygen concentration combustion is performed.

[0003]

However, in the conventional low NO _x burner, modification of the burner nozzle, supply equipment such as steam, or the control thereof, etc. are required in order to reduce the NO _x , resulting in enormous equipment burden and operation will be strong, there is a problem that can not be achieved is sufficiently low nO _X reduction commensurate with the capital investment.

The present invention pays attention to the above-mentioned conventional problems, and
Highly low NO in usual combustor equipment X effect can be expected
Exhaust gas circulation type low NO in the structure_XProviding a burner
The purpose is to

[0005]

In order to achieve the above object, a low NO _x burner for circulating exhaust gas in a furnace according to the present invention is
In a burner in which a plurality of nozzles for injecting fuel toward a combustion chamber are arranged and an inlet for combustion air is opened in the combustion chamber, an exhaust gas introduction passage opening in a furnace is provided with a fuel outlet in which the nozzle is installed. A venturi is connected to the exhaust gas, and a passage extending from the exhaust gas introduction passage to the fuel outlet is formed as a venturi so that the exhaust gas in the furnace is sucked by the fuel injection energy and mixed and burned.

[0006]

According to the above-mentioned structure, since the exhaust gas in the furnace having a high emission concentration of nitrogen oxides is recirculated, mixed with the fuel and burned, the NO _x can be reduced, but especially the forced exhaust of the exhaust gas in the furnace is forced. Circulation does not require injection steam or the like. That is, when the fuel is simply injected from the fuel injection nozzle, the exhaust gas in the furnace is forcibly circulated through the exhaust gas introduction passage to be supplied to the combustion chamber by the Venturi effect at the fuel outlet, and mixed combustion is performed. Therefore, the circulating exhaust gas amount is determined by the fuel injection energy, and the required in-reactor exhaust gas circulation amount is always optimally determined. For this reason, the equipment and facilities required for low NO _x reduction are not required at all, and the energy required for forced circulation is used as fuel injection energy. It can be easily applied to reduce NO _x .

[0007]

EXAMPLES Below, exhaust gas circulation type low N in a furnace according to the present invention
A specific example of the O _X burner will be described in detail with reference to the drawings.

FIGS. 1 and 2 are a sectional view and a plan view of a low NO _x burner according to an embodiment. This burner is formed by tiles on the furnace wall (or hearth, hereinafter the same) 12 portion of the furnace 10. That is, a cylindrical combustion chamber 14 opening to the surface of the furnace wall 12 is formed, and in order to supply combustion air from the bottom of this combustion chamber 14, an air supply duct 16 is connected to the back of the burner. The amount of supply air can be adjusted by a register 18 provided in the supply passage of the duct 16. The combustion air supplied from the air supply duct 16 is introduced into the combustion chamber 14 from the air outlet 20 opened at the bottom of the combustion chamber 14, and the main outlet mainly opened at the center of the bottom. It is composed of 20A and a sub outlet 20B that is open to the periphery thereof.

Further, a fuel outlet 22 is opened at a corner portion between the inner wall and the bottom of the combustion chamber 14, and inside the fuel outlet 22 is 2 to 10 along the circumferential direction of the combustion chamber 14. Individual fuel injection nozzles 24 are provided.
The fuel supply pipe 26 of the fuel injection nozzle 24 is located on the outer peripheral portion of the sub outlet 20B and communicates the air supply duct 16 and the fuel outlet 22 with the air outlet 20C.
The injection nozzle 24 faces the fuel outlet 22 through the center of the outlet 20C.
The injection direction of the fuel injection nozzle 24 is along the inner wall surface of the combustion chamber 14, so that the injected fuel is scroll-supplied and the air outlets 20A, 20B, 2 are provided.
The combustion air supplied from 0C is mixed in the combustion chamber 14,
It is injected into the furnace.

Here, the fuel outlet 22 in which the fuel injection nozzle 24 is arranged is connected to an exhaust gas introducing passage 28 which is located in the outer peripheral portion of the combustion chamber 14 and opens into the furnace 10 as shown in the figure. There is. That is, the exhaust gas introduction passages 28 are provided around the combustion chamber 14 in the number corresponding to the fuel outlets 22. The exhaust passages 28 open on the inner wall surface of the furnace 10 and are curved inside the burner tile. 14
Is formed so as to communicate with the fuel outlet 22 to form a continuous passage. The exhaust gas introduction passage 28 is formed so that the cross-sectional area of the passage gradually decreases from the opening 30 into the furnace 10 to the base of the fuel outlet 22 where the fuel injection nozzle 24 is installed. The base of the mouth 22, that is, the installation location of the nozzle 24 is formed so as to have a minimum cross-sectional area, and the fuel outlet 22 continuous to this is enlarged in passage cross-sectional area toward the opening to the combustion chamber 14 (enlargement). The angle θ) is formed as a diffuser. Therefore, the exhaust gas introduction passage 2
The entire passage from 8 to the fuel outlet 22 is formed as a Venturi pipe portion. Then, the fuel injection nozzle 24
By injecting fuel from the furnace, the exhaust gas in the furnace is sucked by the fuel injection energy and introduced into the combustion chamber 14,
The combustion exhaust gas inside can be mixed and burned.

According to the in-furnace exhaust gas circulation type low NO _x burner thus constructed, fuel such as gas and oil is injected from the fuel injection nozzle 24, and the air outlet 20 is provided.
Combustion is performed by supplying combustion air from the above, and a stable flame can be generated while adjusting the supply amount of combustion air by the register 18. At this time, when the fuel is injected and supplied from the fuel injection nozzle 24, the combustion exhaust gas in the furnace 10 is introduced by the injection energy of the fuel into the introduction passage 28.
Is circulated and supplied into the combustion chamber 14 through. As a result, the fuel mixture gas exhaust gas is mixed, the oxygen partial pressure is reduced by the lean combustion, it is possible to reduce the NO _X reduction. At this time, the amount of circulating exhaust gas required for low NO _X depends on the fuel injection energy, and the amount corresponding to the required amount is automatically adjusted, and a large amount of circulating exhaust gas flows into the combustion chamber 14 when the capacity is small. Does not cause instability of the flame.

Suction efficiency of combustion exhaust gas is low NO _{x as it is}
Although directly connected to the performance, the suction action depends on the Venturi effect, so the shape around the nozzle 24 affects the suction efficiency. Generally, the amount of gas sucked in the Venturi pipe is 10 times that of fuel when the venturi shape having the highest fuel injection efficiency is used, and 4 to 5 times the fuel injection amount even when the venturi shape has poor fuel injection efficiency. , Usually low NO _x
It can be understood that a sufficient exhaust gas suction force can be obtained because the exhaust gas circulation amount required for conversion is three times the fuel amount.

According to this embodiment, when an oil or gas containing no nitrogen is used as the fuel for the burner, the NO _X reduction rate reaches about 80% of that of the conventional burner, and a dramatic reduction in NO _X is achieved. Could be realized.

As described above, in the burner according to this embodiment,
Since the injection energy of fuel such as gas and oil is directly used as the forced circulation energy of the exhaust gas in the furnace without using a medium such as steam, there is no need to newly prepare the energy required for circulation. without imposing the burden of new equipment and cost, it is possible to achieve high low NO _X effects.

[0015]

As described above, the in-furnace exhaust gas circulation type low NO _x burner according to the present invention has a plurality of nozzles for injecting fuel toward the combustion chamber and burns the inlet for combustion air. In a burner having an opening in a chamber, an exhaust gas introduction passage opening in a furnace is connected to a fuel blowout port in which the nozzle is installed, and a passage from the exhaust gas introduction passage to the fuel blowout port is formed as a venturi to inject fuel. Since the exhaust gas in the furnace is sucked by the energy and mixed and burned, by simply forming the exhaust gas introduction passage,
Effects which may be a conventional combustor general of the burner can be expected high low NO _X effects equipment can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of an in-reactor exhaust gas circulation low NO _x burner according to an embodiment.

FIG. 2 is a plan view of FIG.

[Explanation of symbols]

 10 furnace 12 furnace wall 14 combustion chamber 16 air supply duct 18 register 20 (20A, 20B, 20C) air outlet 22 fuel outlet 24 fuel injection nozzle 26 fuel supply pipe 28 exhaust gas introduction passage

Claims (1)

[Claims] 1. In a burner in which a plurality of nozzles for injecting fuel toward a combustion chamber are arranged and an inlet for combustion air is opened in the combustion chamber, the nozzle is provided with an exhaust gas introducing passage opening in a furnace. Reactor exhaust gas circulation characterized in that it is connected to an installed fuel outlet and the passage from this exhaust gas introduction passage to the fuel outlet is formed as a venturi to suck the exhaust gas in the reactor by fuel injection energy to perform mixed combustion. Type low NO _x burner.