JPS599003B2 - Method and device for suppressing nitrogen oxides - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention is a gas burner for industrial furnaces that injects gas from the inner area of the nozzle plate and combustion air from the outer area at high speed. The present invention relates to a method and apparatus for effectively suppressing nitrogen oxides generated during combustion by ensuring that the fountain system can smoothly inject water without being affected by high-temperature gas in the furnace and that a water gasification reaction can take place. .

Conventionally, as a means of suppressing nitrogen oxides generated during combustion in gas burners for industrial furnaces, jet ports are provided in each of the inner tube through which pressurized steam or water passes, and the outer tube through which fuel passes.
In a heavy pipe burner, a burner with a jet nozzle provided in the inner pipe close to a jet port provided in the outer pipe and opened at a right angle or close to a right angle to the longitudinal direction of the burner is installed in front of the burner tile. There is a device that is attached to a heating furnace equipped with
(See the microfilm photographing the contents of the specification and drawings attached to the application No. 1834).

Although this device removes nitrogen oxides from the combustion exhaust gas by forcibly mixing liquid particles into the gas jet before mixing with the combustion air, the burner itself is exposed inside the heating furnace. Moreover, the amount of water that spews out from the spout of the inner tube is extremely small.As a result, when the temperature near the spout date is heated to 700-800℃ by the high temperature gas in the furnace, the water from the spout will The water turns into high-temperature, high-pressure steam, creating back pressure and preventing water from gushing out.

Therefore, when the temperature inside the furnace is relatively low in the initial stage, water can be smoothly jetted out from the inner pipe of the burner, but when the inside of the furnace is at high temperatures, the water jetting function is significantly reduced, making it difficult to use, or it may become difficult to use. In order to eliminate this problem, it is necessary to use a large amount of high-pressure water fountain, and the particle size of the fine particles increases, which significantly reduces thermal efficiency, and also causes problems before nitrogen oxide control, such as poor ignition due to mixing with gas. .

This invention has been made in view of the above points, and its purpose is to provide a gas burner for industrial furnaces in which gas is injected from the inner region of the nozzle plate and combustion air is injected from the outer region at high speed. Before being forcedly mixed into the gas jet before mixing, the liquid in the high-speed swirling flow spouted from the fountain system is effectively protected from the high-temperature gas in the furnace by a constricted jet air film, while the liquid in the swirling flow is When it is further atomized, it is thoroughly stirred and mixed with 5 to achieve water gasification,
It is an object of the present invention to provide a method and device for effectively suppressing nitrogen oxides generated during combustion by allowing a fountain system to function smoothly without back pressure or the like even under high temperatures inside a furnace.

Hereinafter, the present invention will be explained based on the drawings.

In the figure, 1 is a nozzle plate, inside which gas a
An injection port 2 for combustion air b is provided in the outer area, and an injection port 3 for combustion air b is provided in the outer area.

The injection ports 2 for the gas a are provided so as to be inclined outward, and the injection ports 3 for the combustion air b are provided to be inclined inward.
, 3 are mixed and ignited by a pilot burner (not shown) to form a flame.

Reference numeral 4 denotes a tubular heat transfer member fitted into the center of the nozzle plate 1 from the inside of the plate so as to be orthogonal to the plate.

The heat transfer member 4 forms a plurality of air passages along the axis at predetermined intervals on concentric surfaces within its wall thickness, and a plurality of air passages are formed on the front end surface of the heat transfer member 4 communicating with each corresponding air passage. An air outlet 4' is provided.

A portion b' of the combustion air b is injected inward from a plurality of air discharge ports 4' arranged concentrically on the front end surface of the heat transfer member 4 in a narrow shape to form an injected air film. The air film effectively protects the fine liquid particles in the high-speed swirling flow, which will be described later, from the high-temperature gas in the furnace and prevents back pressure from working.

Although the injected air film is heated during the process of passing through the air passage of the heat transfer member and is further heated by the high-temperature gas inside the furnace, it is continuously injected and acts as a kind of air curtain, so the temperature inside the furnace does not change. The temperature range must be much lower than that of the previous one, and must be in a temperature range sufficient to prevent back pressure from occurring.

Further, the end of the air passage communicating with the air discharge port 4' communicates with an air flow pipe 7 extending vertically within the gas flow pipe 6 communicating with the injection port 2 of the gas a.

Reference numeral 5 denotes a liquid nozzle body which is arranged concentrically so that a certain annular gap S is left in the heat transfer member 4 and its tip is located at a position recessed from the heat transfer member 4.

The reason why the tip of the liquid nozzle body 5 is recessed from the heat transfer member 4 is because
This is to reduce the thermal influence of high temperature gas in the furnace.

The liquid nozzle body 5 is provided with a nozzle piece 9 for swirling the liquid C therein, and has a structure in which the swirling flow through the nozzle piece 9 can be jetted in the form of fine particles at high pressure.

The fine liquid ejected from the tip nozzle of the liquid nozzle body 5 enters and reflects toward the inner wall of the tip of the heat transfer member, and the water gas after the reflection breaks through the constricted injected air film. It is designed for forced mixing in the gas jet before mixing with the combustion air.

Further, the liquid nozzle body 5 communicates with a liquid flow pipe 8 that runs vertically within the air flow pipe 7.

This liquid flow pipe 8 is in close contact with the rear inner wall of the heat transfer member 4 via an annular projection 8' provided at its tip, and the annular projection 8' allows the air flowed by the air flow pipe 7 to By preventing the leakage of the annular gap S, the ring 5 can also serve as a spacer for the annular gap S.

Thus, the liquid C in the liquid nozzle body 5 passes through the nozzle piece 9, swirls at high speed, becomes fine particles, and is jetted at high speed from the tip nozzle of the liquid nozzle body 5, and the fine liquid C passes through the nozzle piece 9 and is jetted at high speed.
By violently hitting the inner wall of the tip of the heat transfer member 5, the fine particles are further broken down into ultrafine particles (30 to 50μ), and at the same time, they are heated to a high temperature by receiving heat from the inner wall of the heat transfer member 4, and turn into water gas. I can do it.

On the other hand, the water gas is protected from the high-temperature gas inside the furnace by being covered with a jet air film that jets out in a narrow shape from the air discharge port 4' around the outside, and the water gas is protected from the high-temperature gas in the furnace without generating back pressure. Forced mixing occurs in the gas jet before it breaks through the membrane and mixes with the combustion air.

As can be seen from the above description, the present invention provides a gas burner for industrial furnaces in which gas is injected from the inner region of the nozzle plate and combustion air is injected from the outer region at high speed. is injected at high pressure in the form of fine streams so as to enter and reflect toward the inner wall of the tip of the tubular heat transfer member fitted in the center of the nozzle plate, and at the time of reflection, the temperature of the atomized liquid is raised and at the same time it is further atomized. While turning into water gas, part of the combustion air is injected inward from the front end face of the heat transfer member in a constricted shape to protect the water gas from the high temperature gas in the furnace, and furthermore, the water gas after reflection is This method of suppressing nitrogen oxides is characterized by forced mixing in the gas jet before breaking through a constricted injection air film and mixing with the combustion air. In the pre-stage where the liquid is forcibly mixed in the furnace, the liquid in the high-speed swirling flow ejected from the fountain system is effectively protected from the high-temperature gas in the furnace by a constricted jet air film, while the liquid in the swirling flow is further atomized. The water gas is sufficiently stirred and mixed to achieve water gasification, and the fountain system can function smoothly without back pressure or the like even at high temperatures inside the furnace.

In addition, as mentioned above, since the fountain system does not receive back pressure, there is no need to inject a large amount of water at high pressure from the fountain system as in the past, and only a small amount is required. It is possible to mix in a small amount of water gas, and it is possible to rationally suppress nitrogen oxides during combustion without reducing thermal efficiency or causing ignition failure.

In addition, in a gas burner for an industrial furnace that injects gas from the inner region of the nozzle plate and combustion air from the outer region at high speed, a tubular heat transfer member is fitted in the center of the nozzle plate, and the wall thickness of the heat transfer member is A plurality of air jet ports are provided on the front end surface of the heat transfer member so that a part of the combustion air passing through the air passage inside is injected forward and inward in a narrow shape, and a certain annular gap is provided within the heat transfer member. A liquid nozzle body is provided concentrically so that the tip is located at a position recessed from the heat transfer member, and a nozzle piece for swirling the liquid is provided in the liquid nozzle body, and further, the tip nozzle of the liquid nozzle body Particulate liquid injected from the heat transfer member enters and reflects toward the inner wall of the tip of the heat transfer member, and the water gas after the reflection breaks through the constricted jet air film and mixes with the fuel air during the gas jet. Since the nitrogen oxide suppressing device is characterized in that it is formed so as to forcefully mix the nitrogen oxides with The liquid nozzle body is protected from thermal damage by high-temperature gas in the furnace due to its concave position5 and the fact that it is protected by an air jet film that is jetted in a constricted shape from the air discharge port on the front end face of the heat transfer member. It can be used for a long time without any damage.

Experimental example: A fast combustion burner with the nozzle plate shown in the drawing (
1 4 0,0 0 0 Kcal load),
Water is pumped from the center of the nozzle plate at a pressure of 2 kg/cya.
When a high-speed swirling flow is injected downward in the form of fine particles at a rate of 84 cc/min, 5,00
0 Kcal of propane gas was injected into combustion air from an external area at high speed, and the particulate injection water was forcibly mixed into the propane gas before the propane gas was mixed with the combustion air.

The reduction rate of nitrogen oxides in the combustion gas at the furnace temperature at this time was as follows.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of the device of the present invention, and FIG. 2 is an enlarged view of the main parts. 1... Nozzle plate, 2... Gas injection port, 3... Combustion air injection port, 4...
Heat transfer member, 5... Nozzle body.

Claims (1)

[Claims] 1. In a gas burner for an industrial furnace that injects gas from the inner region of the nozzle plate and combustion air from the outer region at high speed, a liquid in a high-speed swirling flow is injected from a concave position in the center of the nozzle plate to the nozzle plate. The liquid is jetted at high pressure in the form of fine particles so as to enter and reflect toward the inner wall of the tip of the tubular heat transfer member fitted in the center of the tube, and at the time of reflection, the temperature of the atomized liquid is increased, and at the same time, it is further atomized and turned into a water gas. , a part of the combustion air is injected inward from the front end surface of the heat transfer member in a constricted shape to protect the water gas from the high temperature gas in the furnace, and furthermore, the water gas after reflection is injected in the constricted shape. A method for suppressing nitrogen oxides characterized by forced mixing in a gas jet before breaking through an air film and mixing with combustion air. 2. In an industrial furnace gas burner that injects gas from the inner region of the nozzle plate and combustion air from the outer region at high speed, a tubular heat transfer member is fitted in the center of the nozzle plate, and the heat transfer member is heated. A plurality of air outlets are provided on the front end surface of the heat transfer member so that a part of the combustion air passing through the air passage within the thickness is injected forward and inward in a narrow shape, and a certain annular gap is provided within the heat transfer member. A liquid nozzle body is provided concentrically so that the tip is located at a position recessed from the heat transfer member, and a nozzle piece for swirling the liquid is provided in the liquid nozzle body, and further, the tip nozzle of the liquid nozzle body The fine particulate liquid injected from the heat transfer member enters and reflects toward the inner wall of the tip of the heat transfer member, and the water gas after the reflection breaks through the constricted jet air film and mixes with the combustion air in the gas jet. A nitrogen oxide suppression device characterized in that it is formed so as to perform forced mixing.