JPS5841406B2 - Nitrogen oxide suppression type burner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a burner that has a structure that can greatly suppress nitrogen oxides (NOx) generated during combustion in burners that burn liquid fuel or gaseous fuel used, for example, in various furnaces. It is related to.

It is already known that, in general, as the flame temperature in a burner increases, the amount of nitrogen oxides (NOx) generated increases.

For this reason, attempts have been made to suppress the rise in flame temperature by reducing the amount of excess air to a very low level to bring it close to the stoichiometric mixing ratio, or by recirculating the exhaust gas and mixing it with the combustion air. It is being

On the other hand, it has been known that the circulating vortex of combustion flame has a great effect on suppressing NOx.

In the latter case, a conventional method has been used in which combustion gas (or furnace gas) is circulated using air-fuel ejection energy to generate a circulating vortex.

However, the structure of burners of this structural type is generally complicated, and there are many problems with the high-temperature fireproof structure.
In addition, there are various disadvantages such as a decrease in heat transfer efficiency due to high pressure of combustion air and slow combustion, and furthermore, B and C heavy oils are structurally unsuitable for use as fuel.
The effect of suppressing Ox has not yet been achieved sufficiently.

Invention +3 It is an object of the present invention to easily provide a burner with an extremely simple structure that can effectively suppress NOx by using the circulation vortex of the combustion flame described above.

That is, the first object of the present invention is to generate an effective circulating vortex phenomenon in the flame combustion part by injecting air while giving it a swirling motion, and to greatly suppress NOx. The purpose is to provide a burner with an extremely simple structure that is durable and easy to manufacture, use, and maintain and inspect.

The present invention will be explained in more detail below based on illustrated embodiments.

As shown in Figure 1 (partially cutaway perspective view) and Figure 2 (cross-sectional view), the burner installed toward the furnace A consists of a fuel injection pipe 1 installed on the central axis of the burner, and a fuel injection pipe 1 installed on the central axis of the burner. It is comprised of an outer air injection pipe 2 that is inserted into the interior and supplies fuel air toward the combustion section.

This air injection pipe 2 has a special shape and structure, as will be described later.

That is, the rear half of the main body of the air supply pipe 20 is made into a large-diameter swirl pipe part 3 as shown in the figure, and the air flow axis is moved in a direction that blocks the air passage in the annular space between it and the fuel injection pipe 1 inserted into the center of the interior. For this purpose, a guide vane 4 is attached to the inner wall of the pipe portion, and the guide vane 4 is formed by forming a ring shape in which a large number of swirling vanes are arranged in parallel in the circumferential direction and are turned at an angle of 45° to 60°. Air supplied from the rear and upper side is given a swirling motion when it passes through the guide vanes 4, and is configured so that it is powerfully injected into the furnace A while swirling as shown by the thin line in the figure.

Then, the outlet end of the air swirling tube part 3 is connected to a speed increasing throttle part 5 (the throttle ratio is approximately 0.4 to 0.8) with a small diameter end.
Further, the tip thereof is connected to the rear part of an air temperature passage 7 which has the same diameter as the constriction part 5 and has no widening at the end, surrounded by a refractory material such as a burner tile 6, so that air passes through the passage. It is configured to be injected into the furnace A while rotating as shown by the arrow in the figure.

The length L with respect to the diameter of the air temperature passage 7 is equivalent to g4 times, and the tip of the fuel injection pipe 1 inserted into the passage is further away from the opening at the tip of the passage 7. It is inserted to a point within the range of 0.1 to 4.0 times the diameter.

This is because if the zero distance between the two is 4.0 or more, combustion will start in the air temperature passage I, which will combine with the radiant heat from the burner tile wall to increase the flame temperature and raise NOx. This is because if it is less than 0.1, the mixing of the +-g natural material and air will deteriorate and more soot will be produced, which is undesirable.

Since the burner of the present invention has the structure explained in the above embodiment, the air supplied to the air injection pipe 2 undergoes a swirling motion when passing through the guide vane 4 provided in the air swirling tube section 3 having the above-mentioned structure. While swirling, the flow velocity is further increased as it passes through the constriction section 5 provided for increasing the flow velocity, and as the air swirls as shown by the thin line in the figure, it passes through the air vortex passage I and enters the furnace A. - Injected.

Therefore, as shown in Fig. 3, this air flow is controlled by suppressing the spread angle of the fuel injected from the fuel injection pipe 1 within the range of 5° to 60°, preventing it from touching the peripheral wall of the air temperature passage 7, and preventing the spread of the fuel from spreading at the end. This is to conduct combustion by guiding the burner tiles into the furnace space away from the wall surface through a narrow passage outlet end angle, thereby preventing the occurrence of overheating of the burner tiles. The swirling vortex creates a low-pressure area near the center, so that a desirable circulating flow is formed in the opposite direction as shown by the thick line in the figure.

On the other hand, 5° to 60' from the tip of the fuel injection pipe 1 in the direction of the flow axis.
The fuel oil or gas injected into the furnace A at an angle of is collided with the circulating flow of high-temperature combustion gas inside the furnace A, and the oil particles quickly become a gas, and in the case of a gas, they quickly diffuse into the air. While mixing, combustion begins due to the airflow of air temperature surrounding the outer periphery.

This combustion takes place much more rapidly than normal oil combustion because the high-temperature combustion gases are already in a gaseous state due to the circulating flow.

That is, there is a significant effect that the circulating flow of high-temperature combustion gas collides with the fuel, causing rapid thermal combustion.

At the same time, due to the swirling air flow, an atomized gas band is generated from the tip of the fuel injection pipe 1 as shown in Fig. 3, and a flame formation band is generated at the tip, so that the combustion area is not perpendicular to the burner axis. It doesn't spread.

Incidentally, when comparing the flame temperature pattern of the burner of the present invention with that of a conventional conventional burner using an oil-fired burner as an example, the flame temperature pattern is as shown in FIG.

That is, in a conventional normal burner, the temperature inside the burner tile becomes locally high and NOx is generated, but in the present invention, as described above, the temperature inside the burner tile is increased and NOx is generated. As is clear from the figure, the maximum flame temperature is also about 100 degrees Celsius lower than that of a normal burner, and the high temperature position moves into the furnace, and the temperature pattern is also characteristically gentle and normal.

This occurs because the above-mentioned circulating flow of high-temperature combustion gas dilutes the flame, and as a result, this has a significant effect of significantly suppressing the target NOx generation in the burner.

The following table shows the NOx production value of the burner of the present invention compared with that of a conventional burner using an oil-fired burner as an example.

(However, the furnace temperature is 1250℃, the fuel is Minas heavy oil NOx PP
(M is an 11 coefficient 02 equivalent value) As shown in the comparison table above, the burner of the present invention has a NOx production value of approximately 40% compared to the conventional burner, and therefore the present invention significantly contributes to the NOx suppressing effect. It was shown that

In this way, according to the present invention, by having the above-described structure, it is possible to generate a desirable circulation flow of combustion gas, thereby reducing the oxidation of generated nitrogen, which is pointed out as one of the industrial pollutions in today's various combustion appliances. It is possible to achieve a large reduction in suppression of the material, and in addition, its structure is simple and not complicated, so it has good durability as a burner.
Moreover, since it is possible to provide a burner that has many functions and effects, such as being easy to manufacture, inexpensive, and easy to maintain and inspect, the benefits to manufacturing industries that use various furnaces, boilers, etc. are truly remarkable.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view showing the structure of an embodiment of the burner of the present invention, FIG. 2 is a cross-sectional structural view of FIG. 1, and FIG. 3 is a cross-sectional view explaining the operation during combustion. FIG. 4 is a comparison diagram showing the flame temperature patterns of the example burner and a conventional ordinary burner. A is a furnace, 1 is a fuel injection pipe, 2 is an air injection pipe, 3 is a swirl tube portion thereof, 4 is a guide vane, 5 is a throttle portion, 6 is a refractory, and 7 is an air temperature passage.

Claims (1)

[Claims] 1 Installed on the central axis of the burner and directing the fuel 5
It consists of a fuel injection pipe that injects at an angle of ~60°, and an outer air injection pipe that passes through the fuel injection pipe and supplies air.The air injection pipe supplies air to the internal air passage. An air swirl tube section provided with guide vanes capable of imparting swirling motion to the air swirl tube section, and a throttle section for increasing speed formed at the tip of the swirl tube section, and an air swirl tube section of the same diameter formed of a movable propellant at the tip of the throttle section. The tip of the fuel injection pipe is connected to an air vortex passage that does not widen at the end, and in this case, the tip position of the fuel injection pipe facing into the air vortex passage is within a range of 0.1 to 4.0 times the diameter of the passage with respect to the outlet end of the air vortex passage. The fuel injected from the fuel injection pipe is burnt in a furnace space away from the burner tile wall by creating a circulation flow in the combustion gas. Nitrogen oxide suppression type burner.