KR20100061322A - Diffusion combustion burner - Google Patents

Abstract

PURPOSE: A diffusion and combustion device is provided to increase the heat recovery efficiency by a thermal energy storage material. CONSTITUTION: A diffusion and combustion device comprises a primary combustion chamber(4), a pilot burner(5), a fuel nozzle(6), a first and a second air supply passages(7,8), and a first air ratio control unit. The primary combustion chamber is opened to a main combustion chamber(2). The pilot burner is installed in the primary combustion chamber. The fuel nozzle sprays the fuel on the primary combustion chamber. The first air supply passage supplies the primary air along the fuel nozzle around the fuel nozzle. The second air supply passage sprays the secondary air from near the primary combustion chamber to the main combustion chamber. When the temperature of the main combustion chamber is low, the first air ratio control unit increases the first excess air ratio. When the temperature of the main combustion chamber is high, the first excess air ratio control unit reduces the first excess air ratio.

Description

[0001] DIFFUSION COMBUSTION BURNER [0002]

The present invention relates to a diffusive combustion device.

Patent Document 1 discloses a diffusive combustion apparatus that directly injects fuel and air into a combustion chamber and burns the fuel and air into the primary combustion chamber and injects fuel and primary air into a primary combustion chamber that is opened in the main combustion chamber and provided with a pilot burner, Discloses a diffusive combustion apparatus that injects secondary air from the vicinity of the main combustion chamber.

Patent Document 2 discloses a method of controlling the amount of combustion of a secondary combustion air in which a secondary air supply passage and an exhaust gas exhaust passage are alternately operated and a diffusive combustion Device is described.

Such a regenerative type diffusive combustion apparatus is practically used for gas fuel, but it is not yet practical for liquid fuel. Particularly, in a combustion device having a large combustion capacity, there is a great demand for using heavy oil as fuel. However, since the liquid fuel needs to temporarily vaporize the sprayed fuel, ignition delay or rapid combustion may occur particularly at low temperatures, resulting in incomplete combustion, furnace walls, (Particularly, carbon deposition on the inner wall of the primary combustion chamber).

(Patent Document 1)

Japanese Patent Publication No. Hei 8-26970

(Patent Document 2)

Japanese Patent Application Laid-Open No. 2007-24335

In view of the above problems, it is an object of the present invention to provide a diffusive combustion device capable of using a liquid fuel.

According to an aspect of the present invention, there is provided a diffusion combustion apparatus comprising a primary combustion chamber opened in a main combustion chamber, a pilot burner installed in the primary combustion chamber, a fuel nozzle for injecting fuel into the primary combustion chamber, A secondary air supply path for injecting secondary air into the main combustion chamber from the vicinity of the primary combustion chamber, a secondary air supply path for injecting secondary air into the main combustion chamber from the vicinity of the primary combustion chamber, The ratio of the primary air to the total amount of the primary air and the secondary air is made to be high when the temperature of the main combustion chamber is low and is made low when the temperature of the main combustion chamber is high Primary air ratio adjusting means.

According to this configuration, the primary air ratio is increased when the temperature is low, and the sprayed fuel is surrounded by the primary air, thereby preventing the combustion incomplete fuel from adhering to the wall of the furnace. In particular, . Further, when the fuel is at a high temperature at which vaporization and combustion are easy, NOx can be reduced by lowering the primary air ratio.

Further, when the diffusive combustion apparatus of the present invention further includes an air flow pivoting means for pivoting the primary air around the fuel nozzle, the swirling air flow becomes an air curtain to enclose the fuel, The effect of preventing the carbon from adhering to the inner wall of the combustion chamber can be enhanced.

In addition, in the diffusive combustion apparatus of the present invention, when the primary air ratio at the time of the temperature of the main combustion chamber is set to 5% or more, preferably 10% or more, carbon adhesion to the inner wall of the primary combustion chamber Can be effectively prevented. Further, by setting the primary air ratio to 40% or less, the generation of NOx can be suppressed within the regulation range of the industrial furnace.

Further, in the diffusive combustion apparatus of the present invention, a sufficient NOx suppressing effect can be obtained by setting the primary air ratio at 10% or less when the temperature of the main combustion chamber is high.

In the diffusive combustion apparatus of the present invention, a plurality of secondary air supply passages are alternately provided for alternately serving as a flow path for exhausting the combustion gas, and the secondary air is introduced through the heat accumulator, Since the secondary air can be preheated by the heat recovered from the exhaust gas in the sieve, the thermal efficiency can be increased. When the temperature of the main combustion chamber is high, the ratio of the secondary air is increased by lowering the primary air ratio, so that the thermal efficiency is further increased.

As described above, in the diffusive combustion apparatus of the present invention, when the temperature of the main combustion chamber is low, by increasing the primary air ratio, it is possible to prevent the primary air from becoming an air curtain and the sprayed fuel to adhere to the inner wall of the primary combustion chamber When the temperature of the main combustion chamber is high, the primary air ratio is lowered to suppress NOx, and the efficiency of heat recovery by the regenerator can be improved.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Now, embodiments of the present invention will be described with reference to the drawings. Fig. 1 shows a diffusive combustion apparatus 1 according to one embodiment of the present invention. The diffusive combustion apparatus 1 is formed in a furnace wall 3 for defining a main combustion chamber 2. The furnace wall 3 is formed in a main combustion chamber 2, The diffusive combustion apparatus 1 includes a primary combustion chamber 4 formed as a recess formed in the furnace wall 3 so as to be opened in the main combustion chamber 2 and a primary combustion chamber 4 serving as an ignition source in the primary combustion chamber 4 A fuel nozzle 6 for injecting fuel into the main combustion chamber 2 through the primary combustion chamber 4 and a fuel nozzle 6 mounted on the outside of the fuel nozzle 6 A primary air supply passage 7 which is formed by a pipe and supplies primary air around the fuel nozzle 6 and a secondary air supply passage 7 which is formed in the main combustion chamber 2 from the vicinity of the primary combustion chamber 4, A plurality of secondary air supply passages 8 (only one is shown) capable of injecting air and a regenerator 9 are provided respectively and the regenerator 9 is connected to the secondary air supply passage 8, (Only one is shown) capable of supplying secondary air to the secondary air supply path 8 through a plurality of heat exchangers.

At least one of the secondary air supply passages 8 and one regenerator 10 is used as an intake passage of the secondary air in order and at the same time, At least one equation is used as an exhaust path of the combustion exhaust gas. The regenerator 9 recovers the thermal energy of the combustion exhaust gas when used as an exhaust path and preheats the secondary air when it is used as an intake path of the secondary air.

In the present embodiment, the liquid fuel (for example, heavy oil) and the spray air for spraying the liquid fuel are supplied to the fuel nozzle 6, but the liquid fuel may be sprayed at a high pressure without using the spray air. The primary air supply passage 7 also has a pivoting blade 11 for pivoting the primary air around the fuel nozzle 6.

In the diffusive combustion apparatus 1, the blowing air is supplied by the blower 12 at a flow rate that realizes the optimum air-fuel ratio (air-fuel ratio) in accordance with the amount of fuel injected from the fuel nozzle 6, And is distributed to the supply path (7) and the heat storage chamber (10). A main supply damper 13 and an increasing supply damper 14 are provided in parallel in the flow path for supplying the primary air. In the diffusive combustion apparatus 1, when only the main supply damper 13 is opened, 5% of the total amount of air for combustion is introduced into the primary air supply path 7 as primary air, and the main supply damper 13 and the increase When the supply damper 14 is opened together, 10% of the total amount of air for combustion is designed to be introduced into the primary air supply path 7 as primary air.

The diffusive combustion apparatus 1 further includes a temperature detector 15 for measuring the temperature in the main combustion chamber 2 and detects the temperature detected by the temperature detector 15 at a predetermined set value, When the temperature is equal to or higher than 800 ° C, the increase supply damper 14 is closed. In other words, in the diffusive combustion apparatus 1, the primary air ratio, which is the ratio of the primary air to the total amount of the primary air and the secondary air, is lower than the primary air ratio when the temperature of the main combustion chamber 4 is low , And when the temperature of the main combustion chamber 2 is 800 占 폚 or more, it is set as low as 5% (primary air ratio adjustment means).

2 shows the relationship between the primary air ratio of the diffusive combustion apparatus 1 and the NOx concentration in the combustion exhaust gas. As shown in the figure, the higher the primary air ratio, the higher the NOx concentration, but this relationship is generally known in a combustion apparatus using liquid fuel. Further, the NOx concentration increases sharply when the primary air ratio exceeds 40%. Further, in general, the NOx concentration of the exhaust gas is limited by laws and ordinances. For example, in Japanese law, the upper limit is 120 to 150 ppm in terms of an oxygen concentration of 11% with respect to an industrial furnace, so it is appropriate to set the upper limit of about 100 ppm as the product standard for industrial use. Therefore, in the diffusive combustion apparatus 1 of the present invention, the primary air ratio should be 40% or less. Further, if the primary air ratio can be made 10% or less, the NOx concentration of the exhaust gas can be made sufficiently low, and it is very safe from the viewpoint of the NOx concentration.

Subsequently, the results of checking the change of the state of carbon attachment to the inner wall of the primary combustion chamber 4 of the diffusion combustion device 1 due to the difference in the primary air ratio at room temperature are shown in Table 1. In Table 1, the case where there is a clear carbon adhesion on the inner wall of the primary combustion chamber 4 is indicated by X, the case where it can be confirmed that it is slightly blackened is indicated by?, And the case where there is no soiling is indicated by?. For this experiment, the main supply damper 13 and the increase supply damper 14 were appropriately exchanged for an appropriate capacity.

(Table 1)

Primary Air Ratio (%) 3 5 7 10 15 20 Carbon attachment state × △ △ ○ ○ ○

Thus, in the diffusive combustion apparatus 1, when the primary air ratio at normal temperature was 10% or more, a favorable combustion state without generation of carbon was obtained. Even when the primary air ratio is not satisfied by 10%, good combustion can be obtained depending on the temperature in the main combustion chamber 2 and the temperature of the outside air (combustion air), and when the primary air ratio is 5 %, It was confirmed that incomplete combustion which clearly generates graphite can be prevented. Therefore, in the diffusion combustion device 1, if the primary air ratio is 5% or more and 40% or less at normal temperature, there is no problem with laws and regulations, and there is no problem with incomplete combustion.

Table 2 shows changes in the adhesion state of carbon due to the difference in the primary air ratio when the temperature of the main combustion chamber 2 is 800 ° C.

(Table 2)

Primary Air Ratio (%) 3 4 5 6 7 Carbon attachment state × △ ○ ○ ○

Thus, in the diffusive combustion apparatus 1, when the temperature of the main combustion chamber 2 is high, even if the primary air ratio is reduced to 5%, generation of carbon is not observed.

In consideration of the above combustion conditions, the diffusion combustion apparatus 1 is configured to lower the NOx concentration as much as possible and to obtain the ideal combustion, as described above, at a primary air ratio of 10% And 5% at a high temperature. Thus, even when liquid fuel is used, the diffusion combustion apparatus 1 can obtain good combustion without generation of smoke or carbon adhesion to the wall of the furnace, and the generation of NOx can be limited to the minimum limit.

This is because the unburned fuel generated in a large amount at low temperatures and its incomplete combustible matter CO are wrapped in the primary combustion chamber 4 by the primary air and introduced into the flame formed in the main combustion chamber 2 This is because it is possible to prevent the inner wall of the furnace wall 3, particularly the inner surface of the primary combustion chamber 4, from being attached as carbon or becoming smoke in the combustion exhaust gas. In order to have the effect as the air curtain, in the present invention, it is effective to circulate the primary combustion air around the fuel nozzle 6 and supply the secondary combustion air by the orbiting blades 11 of the present embodiment, to be.

Further, lowering the primary air ratio increases the ratio of the secondary air supplied through the heat accumulator 9 to the total amount of air for combustion. For this reason, it is also possible to raise the thermal efficiency by lowering the primary air ratio as much as possible. For example, when the primary air ratio is 40% or less, the diffusive combustion apparatus 1 can obtain a high thermal efficiency as a regenerative burner apparatus, which is advantageous compared with a burner provided with a waste heat recuperator.

In the diffusive combustion apparatus 1, the gaseous fuel may be used by replacing the fuel nozzle 6 or the tip thereof with a gas fuel such as LNG.

In the above embodiment, the primary air ratio is set to 5% and 10% depending on whether or not the temperature of the main combustion chamber 2 is 800 ° C or higher. However, by using a damper capable of opening degree adjustment , The primary air ratio may be gradually increased in accordance with the temperature rise of the main combustion chamber 2.

In the above embodiment, the threshold value of the temperature of the main combustion chamber 2 at the time of adjusting the primary air ratio is set at 800 DEG C, but this temperature set value is usually set so that the sprayed liquid fuel spontaneously ignites Temperature.

In the above embodiment, the primary air ratio is set to 10% when the temperature is low and 5% when the temperature is high. However, this is an example, and in another embodiment, the optimum primary air ratio may be different depending on the combustion apparatus have. Therefore, the present invention is intended to set the primary air ratio at a high temperature to a value lower than that at a low temperature, and the value may be different from that of the above embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view showing a configuration of a diffusive combustion apparatus according to one embodiment of the present invention. Fig.

2 is a graph showing the relationship between the primary air ratio and the NOx concentration in the diffusive combustion apparatus of FIG.

DESCRIPTION OF THE REFERENCE NUMERALS

1: Diffusion combustion device

2: Main combustion chamber

3: Roof wall

4: Primary combustion chamber

5: Pilot nozzle

6: Fuel nozzle

7: primary air supply path

8: Secondary air supply path

9:

10: Opening the axis

11: turning blade (airflow turning means)

12: blower

13: Main supply damper

14: Increasing supply damper

15: Temperature detector

Claims (6)

A primary combustion chamber opening into the main combustion chamber, A pilot burner installed in the primary combustion chamber, A fuel nozzle for injecting fuel into the primary combustion chamber, A primary air supply path surrounding the fuel nozzle for supplying primary air along the fuel nozzle, A secondary air supply path for injecting secondary air from the vicinity of the primary combustion chamber into the main combustion chamber, Wherein a ratio of the primary air to a total amount of the primary air and the secondary air is set to be high when the temperature of the main combustion chamber is low and low when the temperature of the main combustion chamber is high And a primary air ratio adjusting means for adjusting the primary air ratio. The method according to claim 1, Further comprising an air current swirling means for swirling the primary air around the fuel nozzle. 3. The method according to claim 1 or 2, Wherein the primary air ratio when the temperature of the main combustion chamber is low is not less than 5% and not more than 40%. The method of claim 3, Wherein the primary air ratio when the temperature of the main combustion chamber is low is 10% or more. 5. The method according to any one of claims 1 to 4, Wherein the primary air ratio when the temperature of the main combustion chamber is high is 10% or less. 6. The method according to any one of claims 1 to 5, Wherein the secondary air supply passage is provided with a plurality of secondary air supply passages for alternately serving as exhaust passages for exhaust gas and each of the secondary air is introduced through a regenerator, Device.

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