JPS60185004A - Three-stage burner - Google Patents

Abstract

PURPOSE:To enable to burn the titled burner by increasing a reduction effect of NOx, expanding a control range of a quantity of combustion and necessitating no auxiliary combustion even with fire retardative fuel, by providing a primary combustion burner on a slipped position to a one direction that is a corner side from the center line running parallel with a furnace axis of each side of a furnace whose cross section is a square. CONSTITUTION:When primary combustion is performed with a primary combustion burner 6, combustion gas is turned in a furnace, to begin with. Secondary fuel for a reduction of NOx is supplied additionary from a nozzle 10, and additional air for complete combustion is supplied further through a nozzle 11 from a downstream side of the nozzle 10. Although three-stage combustion is performed with this construction, filling of combustion gas is fast, diffusion of secondary fuel for the reduction of the NOx and the air for the complete combustion into the combustion gas can be performed fast and the NOx and unburnt amount can be reduced drastically. In addition to the above, as flame gas of a high-temperature from the upstream side burner 6 of the turning arrives directly to a base part of the burner 6 even if a quantity of the combustion has been reduced, a flame lift becomes hard to occur. A control range, therefore, of the quantity of the combustion is expanded.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a three-stage combustion device.

Conventional structure and its problems Traditionally, the burner arrangement in the furnace of a large boiler is generally as shown in Figure 1 at the front of the furnace, the front and back of the furnace as shown in Figure 2, and the corner of the furnace as shown in Figure 3. There is. In each figure, fl)Vi has a rectangular cross-section furnace, +21 is a primary combustion burner provided at the base of the rectangular cross-section furnace (1), (3) is a secondary fuel supply nozzle for NOx reduction provided near the top thereof, (4) is the secondary fuel supply nozzle for NOx reduction (3)
This is an additional air supply nozzle for complete combustion installed near the top of the combustion chamber. By the way, the three-stage combustion apparatus in each of these arrangements has the following problems.

11) In the case of the furnace front arrangement (Fig. 1) a1 Since the main stream of combustion residue is pressed against the rear wall side, in the case of solid flame-retardant fuel such as combustible fuel, it flows along the water pipe wall of the rear wall. It flows easily, and the temperature of the combustion gas near the water/C wall is low because heat is absorbed by the wall, so the combustion speed is slow and combustion is difficult to complete.

bl A temperature region (stagnation region) as shown in the figure is formed downstream from the burner lean on the front wall side, and the main flow of combustion gas flows out of the furnace along the rear wall surface, so the combustion gas in the furnace is short-circuited. The residence time of the gas for NOx reduction is short.

Because of the delay in diffusion and mixing of C1 complete combustion air and the combustion residue containing unburned matter, and the jN gas after mixing, the short pass occurs as described above, so the residence time of 25 gas here cannot be secured sufficiently. Unburned matter is also difficult to burn completely.

dl When the volatile matter in the burnt material is small, such as lime or oil coke, reducing the amount of combustion tends to cause the flame to lift, leading to misfire in extreme cases, but with the front burner arrangement, this misfire limit is -The combustion amount adjustment range is narrow because it occurs immediately.

(2) In the case of the front and rear surfaces of the furnace i3d (Fig. 2) a, the jets on the front and rear surfaces collide and the jets expand and rise vertically and perpendicularly to the jets and oil. For this reason, as shown in the figure, a stagnation area (temperature area) is formed outside the main stream of the jet, and the space cannot be used effectively.
Reduction zone, complete combustion zone) Residence time becomes shorter and NOx
If the reduction effect is not sufficiently exerted, unburned matter also tends to increase.

b. Adjustability of combustion nozzle: At rated load, the flames on the front and rear sides are sealed once, so even if the flame refluxes once, it is unlikely to cause a misfire; however, the amount of combustion has been reduced. In this case, each flame becomes smaller and misfire occurs if the engine is lifted, so the combustion amount adjustment range is still narrow.

3) In the case of the furnace corner arrangement 112 (FIG. 3), a cylindrical vortex is formed at the center of the furnace, but compared to the previous two items, the combustion 15 gas is less likely to short-pass, and the degree of scum filling is improved. However, it has the following drawbacks. 7 a. Because the burner jet is from the [-] part, the jet attracts the low-temperature combustion completion gas on the [-] part, so the flame lifts quickly, but when it lifts, combustion is delayed, so unburned matter is removed. rapidly increasing.

b. If the combustion amount is reduced, each flame becomes an independent flame, and if lifted, it will misfire.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a three-stage combustion device that overcomes the above-mentioned conventional drawbacks.

Structure of the Invention In order to achieve the above object, the three-stage combustion device of the present invention has the following features:
Secondary fuel is additionally supplied from around or downstream of the secondary combustion zone to achieve reducing atmosphere combustion, and NOx generated during fire combustion is replaced with N
In a three-stage combustion device that performs complete combustion by further supplying additional air from the surrounding area or downstream, the new square furnace is deviated to a corner 1011 in one direction from the center line parallel to the furnace axis on each side. The structure is such that the primary combustion chamber is installed at the same position.This makes it possible to maximize the NOx reduction effect, expand the range of combustion amount adjustment, and require auxiliary combustion even with flame-retardant fuels. It can be burned without burning.

Embodiment and Function An embodiment of the present invention will be described below with reference to FIGS. 4 to 6.

In Figures 41 and 54, (5) is a furnace with a square cross section, (Iil is a primary combustion burner installed at the base of the furnace (5) with a square cross section at right angles to the inside of the furnace, and each has a cross section of 1
Triangular furnace (5) Each side of the furnace (1) is provided at a position offset from the center line parallel to the mountain center (7) in one direction toward the corner side.

There is a distance between the center line H11 and the primary combustion burner (6). (10) - 4 secondary fuel supply nozzles for NOx reduction installed near the upper part of the combustion burner (6);
(The river is an additional air supply nozzle for complete combustion provided near the upper side of the secondary fuel supply nozzle (10) for NOx reduction.

With such a configuration, when primary combustion is performed by the -fire combustion burner (6)l, the combustion burner (6)1 first rotates in the furnace. Therefore, secondary fuel for NOx' four sources is additionally supplied from nozzle 1 (11), and additional air for complete combustion is supplied downstream from the nozzle (11).Thus, three-stage combustion is performed. , 1 Jfl The degree of combustion gas filling is higher than that of the conventional example, and the secondary fuel for NOx reduction and air for complete combustion can be diffused into the combustion lotus quickly, significantly reducing NOx and unburned matter. Furthermore, even when the combustion amount is reduced, the high temperature flame from the swirling upstream burner (6) directly reaches the base of the burner (6), making it difficult for flame lift to occur. therefore,
The combustion amount adjustment range will be expanded.

In addition, as shown in Fig. 6, the furnace axis (
The distance between the center line parallel to 7) and the primary combustion burner i (8
), the distance between the center line and the corner (9) exceeds 1, the swirling vortex inside the furnace (5) becomes too large and the flame rises while touching the furnace wall. Since the fuel also runs along the furnace wall, the temperature in this area becomes low, and sufficient NOx reduction does not take place, resulting in a large amount of unburned fuel. T. In addition, if the two arbitrary combustion burners (6) are placed toward the center of the furnace, the 7-mentum on each side of each burner (6), secondary fuel, and additional air will be uniform and severe, resulting in uneven flow and imbalance. The position of the burner fluctuates, which tends to cause pulsating combustion, and when the combustion amount is reduced, the individual burner flames cannot heat the flame base of the separate burner 6), so they tend to lift and misfire.

Effect of the invention According to the present invention, the following effects can be obtained.

iIi jlj and the first page! ! T! Compared to the shield and facing arrangement, the degree of combustion gas filling is higher, and the secondary fuel for NOx reduction and the air for complete combustion diffuse into the combustion gas quickly, so the NOx reduction effect is large. minutes can also be greatly reduced.

(2) Even when the combustion amount is reduced, the temperature flame gas from the swirling upstream (ill bar) directly reaches the burner base, so flame lift occurs. Can be done.

(3) Even flame-retardant fuels with extremely low volatile content, such as oil coke, can be combusted without the need for auxiliary combustion with fuel oil.

[Brief explanation of the drawing]

Figures 1 to 3 show conventional examples, (1) in each figure is a longitudinal sectional view, (b) &, j in each figure: Mizomoe Hyakuzu, fJ4~6
The figures show one embodiment of the present invention, with FIG. 4 being a longitudinal sectional view and FIG.
Figure 6 is a horizontal view. (5)... Rectangular cross-section furnace, (6)...-fire combustion burner, (7)... Sudo/oil core agent Yoshihiro Morimoto Figure f Figure 2 Figure 3 (a) (&) (sword 2 l z

Claims (1)

[Scope of Claims] 1. - Additional secondary fuel is supplied from around or downstream of the secondary combustion zone to achieve reducing atmosphere combustion, - NO generated in the fire combustion
In a three-stage combustion device that reduces x to N2 and additionally supplies air from around or downstream to achieve complete combustion.
[A three-stage combustion device characterized in that a primary combustion burner is provided at a position shifted toward a corner side in one direction from a center line parallel to the furnace axis on each side of a furnace having a rectangular cross section. 2. The distance between the center line parallel to the furnace axis of each side of the trIfi rectangular furnace and the primary combustion burner is set to within 1 of the distance between the center line and the corner. The three-stage combustion device described.