JPS6026922B2 - pulverized coal burner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pulverized coal burner that is capable of reducing the amount of NOx produced during pulverized coal combustion, stable combustion, and reduction of CO and unburned carbon.

Recently, as a pulverized coal burner for low N0x, a pulverized coal dispersion swirler 2 is installed concentrically at the tip of the primary throat 1 as shown in Fig. There is one in which a throat 3 is provided and a burner throat 4 is provided concentrically on the outer circumferential side of the secondary throat 3.

In a pulverized coal burner for low NQ having such a structure, pulverized coal is forced by the primary air through the primary throat ``1'' and is blown into the furnace while being swirled by the swirler 2.

The secondary air is blown out from the secondary throat 3 without swirling,
The tertiary air is blown out from the burner throat 4 in a swirling manner.

The pulverized coal that is blown out while swirling through the swirler 2 is combusted by the primary air to form a primary flame 5.
, the secondary air and tertiary air blown out from the burner throat 4 cause combustion, and a secondary flame 6 is formed. Said primary, 2. The secondary and tertiary air are obtained by dispersing the amount of combustion air required for the entire pulverized coal, but because the primary air and pulverized coal are given a strong swirl, they are quickly combined with the secondary air and tertiary air. Mixing and rapid combustion do not effectively reduce the amount of N○x produced. On the other hand, if the swirling of the primary air and pulverized coal is loosened to avoid rapid mixing with the secondary and tertiary air, the flame holding performance will decrease and the stability of combustion will suffer. , C○, there is a problem that the generation of combustion carbon increases.

The present invention has been made in view of these circumstances, and has investigated the mechanical problems of the low N○x pulverized coal burner described above, and improved the structure to solve the problem. It greatly reduces the amount of NQ generated in the exhaust gas, improves flame holding, and achieves stable combustion, reduces C○ and unburned carbon, improves combustion efficiency, and greatly reduces the N○x concentration in exhaust gas. It is an object of the present invention to provide a pulverized coal burner for ultra-low N○x that can dramatically reduce the amount of nitrogen.

The structure of the pulverized coal burner according to the present invention is shown in Figs. 2 and 3 below.
To explain with reference to the drawings, reference numeral 1 denotes a primary throat for supplying primary air and fine coal, and a swirler 2 for dispersing fine coal is disposed at the tip within the primary throat 1.

At the tip of the primary throat 1, there is a flame holding plate 7 that can expand outward.
A secondary throat 3 for supplying secondary air is provided on the outer peripheral side of the primary throat 1 so as to be movable forward and backward.

A burner throat 4' for supplying tertiary air is provided on the outer peripheral side of the secondary throat 3, and the burner throat 4' is shaped like a diffuser.

In addition, 8 is a swirl vane, and 3 blows out from the burner throat 4'.
This is to swirl the air.

In the pulverized coal burner of the present invention constructed as described above, the pulverized coal is conveyed by the primary air through the primary throat 1, and is blown into the furnace while being gently swirled by the swirler 2. On the other hand, since the secondary air and tertiary air are directed outward by the flame-holding plate 7, mixing of the fine coal with the secondary air and tertiary air is suppressed, and the primary air causes slow low-temperature combustion, resulting in 1 Next flame 5
is formed. Therefore, the primary flame 5 burns with an extremely insufficient amount of 02, and the generation of NQ is significantly reduced. Also this one
The secondary flame 5 is mainly a low-temperature combustion of volatile components of pulverized coal in an 02-deficient state, so char and unburned components (hydrocarbons, NH3, HCN, CO, etc.) that cause a denitrification reaction are generated.
This reacts with N○x and ultimately reduces N○x to N2. Flowing outward by the flame holding plate 7 2
The secondary air and tertiary air flow smoothly while being guided by the outwardly expanding tip inner peripheral surface of the diffuser-type burner throat 4', and a considerable amount of unused air in the primary flame 5 is removed at the tip of the primary flame 5. It mixes with char, which is a fuel, and slowly burns the char at a low temperature to form a secondary flame 6. This secondary flame 6
NQ is generated by the slow, low-temperature combustion of the char, but at the same time, the unburned components are also generated, which are widely distributed in the furnace and remain for a long time, so that the reduction reaction of NQ is promoted by these unburned components. As a result, the NQ concentration is reduced, and the unburned matter is gradually burned, resulting in a decrease in the NQ concentration. However, in the pulverized coal burner of the present invention, since the secondary throat 3 is movable back and forth, the pulverized coal burner has two
By moving the secondary throat 3 forward and backward, the amount of secondary air blown out can be decreased or increased, and the flow of secondary air and tertiary air can be changed.
The combustion of char in the secondary flame 6 can be performed under the best conditions in terms of low NOx and combustion efficiency.

As detailed above, in the pulverized coal burner of the present invention, the pulverized coal is conveyed by primary air through the primary throat and blown into the furnace while being gently swirled by the swirler, and the pulverized coal is blown into the furnace by the secondary air blown out from the secondary throat. The tertiary air blown out from the diffuser-type burner throat flows outward by the flame holding plate that expands outward, and flows ahead of the primary flame along the inner surface of the tip of the burner throat, resulting in a slow 02 shortage. This results in low-temperature combustion, and the amount of NQ produced decreases.

In addition, the flame holding plate ensures sufficient flame holding, so misfires do not occur. In addition, secondary air and tertiary air mix with char, which is a considerable amount of unburned matter in the primary flame, downstream of the primary flame and burn slowly and at low temperature, so NQ generation in the secondary flame is also reduced. . In addition, since the pulverized coal is swirled by a swirler, it is properly dispersed in the furnace in the secondary flame area and diffuse combustion is performed in a wide area with the secondary air and tertiary air, resulting in extremely high combustion efficiency and CO , unburned carbon is significantly reduced. Furthermore, the secondary throat can move forward and backward, and the amount of secondary air and the flow of secondary and tertiary air can be controlled, so the combustion of the secondary flame is achieved under the best conditions in terms of low NQ and combustion efficiency. It can be done with

Therefore, in the pulverized coal burner of the present invention, the pulverized coal combustion becomes ultra-low NQ combustion, the generation of NQ is significantly reduced, and the combustion is stable and efficient, resulting in a significant reduction in CO and unburned carbon. This has an excellent effect.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a secondary pulverized coal burner, and FIG. 2 is a longitudinal sectional view showing a pulverized coal burner according to the present invention. 1...Primary throat, 2...Swahoo for dispersing pulverized coal, 3...Secondary throat, 4'...Diffuser type burner throat, 5...Primary flame, 6
...Secondary flame, 7...Flame holding plate, 8...
...Swirl blade. Figure 1 Figure 2

Claims (1)

[Claims] 1. In a pulverized coal burner, a flame holding plate that can expand outward is integrally provided at the tip of the primary throat, and the secondary throat, which is provided concentrically on the outer circumference of the primary throat, can be moved back and forth;
A pulverized coal burner characterized in that the burner throat provided on the outer peripheral side of the secondary throat is of a diffuser type.