JPS60233403A - Three-stage type combustion device - Google Patents

Abstract

PURPOSE:To perform a combustion with a low NOx while an oxidization atmosphere at a hot temperature part is kept by a method wherein each of the primary combustion burners is arranged at a position which is displaced to the corner part from a center line parallel with a furnace center in the opposing two planes of a rectangular sectional furnace and each of the secondary fuel nozzles is arranged at a position displaced to the corner part in the same direction as that described above from the center line parallel with a center of the furnace of the remaining opposed two planes. CONSTITUTION:Each of the primary combustion burners 2 arranged at the opposing two planes of a vertical furnace 1 is arranged at a position displaced to the corner part in one direction from the center line of the furnace wall which is parallel with the center 3 of the furnace. Each of the secondary fuel nozzles 4 arranged at the remaining two opposed planes of the vertical furnace 1 is displaced to the corner part in the same direction as that described above from the center line of the furnace wall parallel with the center 3 of the furnace at the same height as that of the primary combustion burner 2. Both of secondary fuel nozzles 4 are constructed such that each of the injection directions can be varied in a horizontal direction. Air supplying nozzles 5 to obtain complate combustion are arranged on the center line of the furnace wall parallel with the center axis 3 of the furnace oppositely facing against the upper part of the furnace having the primary combustion burner 2 arranged thereon.

Description

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

Conventional configuration and its problems Conventionally, when three-stage combustion is applied to a vertical boiler, - a fire combustion zone, a reduction combustion zone, and a complete combustion zone must be provided in the vertical direction. The height of the furnace is larger than that of
The disadvantage was that construction costs increased.

In addition, when converting an existing two-stage air combustion system to three-stage combustion, the furnace size Major modifications were required as the burner layout and burner arrangement were different.

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:
In a three-stage combustion device, a rectangular type A primary combustion burner is installed on each of the two opposing sides of the cross-sectional furnace at a position offset from the center line parallel to the furnace axis in one direction toward the corner side, and the center of the remaining two opposing sides parallel to the furnace axis is installed. The structure is such that secondary fuel nozzles are provided at the same height as the secondary combustion burner, shifted from the line to the corner side in the same direction as above, and are thereby installed in the same way as the conventional air two-stage combustion device. The device can be configured with the same furnace dimensions, and low NOx combustion can be performed while maintaining the oxidizing atmosphere in the high temperature section, which is a feature of three-stage combustion. Additionally, an existing combustion device can be easily modified into a three-stage combustion device.

Embodiment and Function An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

In Figures 1 and 2, (l) is a vertical furnace with a square cross section, (2) is a primary combustion burner (main burner) provided on two opposing sides of this vertical furnace (1), Each,
It is arranged at a position shifted toward the corner side in one direction from the furnace wall center line parallel to the furnace axis (3). (4) is a secondary fuel nozzle installed on the remaining two opposing sides of the vertical furnace (υ), and each of them extends from the furnace wall center line parallel to the furnace axis (3) to the cope side in the same direction as above. It is arranged at the same height as the secondary combustion burner (2).

Both secondary fuel nozzles (4) are configured to be able to change their injection directions horizontally. Therefore, the secondary combustion burner (2) and the secondary fuel nozzle (4) are in the same plane, and the secondary fuel nozzle (4) changes the injection direction within this plane. (5) are additional air supply nozzles for complete combustion that are installed opposite to the furnace wall earth where the secondary combustion burner (2) is installed, and each of them is a furnace wall parallel to the furnace axis (3). It is located on the center line. Note that the number of this air supply nozzle (5) may be one.

With this configuration, when combustion is performed using the secondary combustion burner (2) and the secondary fuel nozzle (4), the combustion gas passes through the primary combustion zone (6) and the reduction combustion zone (7) to the downstream side. I'll be heading there. And the downstream air supply nozzle (6)
When additional air for complete combustion is supplied from
8) is formed, in which the combustion gas is completely combusted and reaches the outside of the furnace.

By the way, in this three-stage combustion apparatus, the -fire combustion zone (6) and the reduction combustion zone (7) are formed within the same plane of the vertical furnace 11). Therefore, if the secondary fuel nozzle (4) is kept in a fixed state, when the combustion load is large (when the combustion amount is large), the penetration power of the combustion gas generated in the -fire combustion zone (6) increases, and the high temperature A reducing atmosphere may be formed, leading to slagging and corrosion problems. Therefore, in such a case, as shown in FIG. 8, the injection direction of the secondary fuel nozzle (4) is moved closer to the firing port of the primary combustion burner (2) on the downstream side of the swirling flow. In this way, the primary combustion zone (6) and the reduction combustion zone (7) can be formed well. On the other hand, when the combustion load is small (when the combustion amount is small), the penetration power of the combustion gas generated in the -flame combustion zone (6) decreases, and it flows to the downstream region without mixing with the secondary fuel. There is a risk of it getting lost. Therefore, in such a case, as shown in FIG. 4, the injection direction of the secondary fuel nozzle (4) is moved closer to the reactor axis (3). In this way, the primary combustion zone (6) and the reduction combustion zone (7) will be well formed.

Effects of the Invention According to the present invention, it is possible to construct a furnace with the same furnace dimensions as a conventional two-stage air combustion system, and to maintain the oxidizing atmosphere in the high temperature section, which is a characteristic of three-stage combustion, while maintaining a low N
Ox combustion can be performed.

Furthermore, an existing combustion device can be easily modified into a three-stage combustion device.

[BRIEF DESCRIPTION OF THE DRAWINGS] The drawings show one embodiment of the present invention, in which FIG. 1 is a longitudinal cross-sectional view of a three-stage combustion device according to the present invention, FIG. 2 is a cross-sectional view of the same, and FIGS. Each figure is a cross-sectional view of the same for explaining the operation. (1) Vertical furnace, (2) Secondary combustion burner, (
3) ... Furnace axis center. (4)... Secondary fuel nozzle, (5)... Additional air supply nozzle for complete combustion agent Yoshihiro Morimoto Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1. - Additional supply of secondary fuel to the fire combustion area to achieve reducing atmosphere combustion, - Reduction of NOx generated in the secondary combustion to N2, and then supply of additional air for complete combustion. In a three-stage combustion device, primary combustion burners are provided on each of two opposing sides of a square cross-section furnace at a position shifted toward the corner in one direction from the center line parallel to the furnace axis, and , shifted toward the corner side in the same direction as above from the center line parallel to the furnace axis,
A three-stage combustion device characterized in that secondary fuel nozzles are provided at positions at the same height as the secondary combustion burners. 2. The three-stage combustion device according to claim 1, wherein the injection direction of each secondary fuel nozzle can be changed.