JPS5924105A - Low nox burner - Google Patents

Abstract

PURPOSE:To control the production of CO of high level and to enable concentration of CO exhausted to be reduced on the whole, by positively feeding the air to the vicinity of the side wall of a furnace and promoting mixture. CONSTITUTION:Each burner 3 is provided with an air resister to regulate it so that the air is all revolved clockwise. Air ports 4, positioned right above the burner, are also regulated so that the air is revovled in the same direction. Further, auxiliary air ports 14 and 15 are formed closer to the opposite side walls 8 than the air ports on the side wall side, only the one air port 15 is caused to revolve counterclockwise or in the reverse direction to that of the other air port 14 positioned facing and opposite to the former air port so that all the air currents of the additional air ports turn toward the side wall 8. If the diameter of the additional air ports 14 and 15 are identical to or smaller than that of the air port 4, it can result in displaying the function thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a denitrification combustion device, and particularly to a combustion device such as a boiler that takes measures to reduce nitrogen oxides (NO,) such as two-stage combustion and in-furnace denitrification combustion.

Conventionally, in order to reduce NOx in exhaust gas, as shown in FIG.
Boiler equipment #1 is known, which is equipped with an air port 4 on the upper part of the boiler equipment. In addition, in the figure, 2 is a wind box, and 5 is a furnace. In such a device, each stage burner A, B, C
Fuel or air for the after-air bow (stage D) is supplied into the furnace as shown by the arrows in FIGS. 2 to 5 (top view). Furthermore, in order to stabilize the flame in each burner stage and promote mixing, a circular air register is used to swirl the air in the burner section and the air port. In this case, as shown in FIG.
By interaction with K, Ltta -JoLLlo;
It has been confirmed that a horizontal force 11 is applied according to Ski's law, causing the flame and airflow to curve.

In the multi-stage combustion method described above, it is possible to perform good denitrification combustion, but due to the above-mentioned curvature of the flame or air flow, a lack of combustion air occurs on both sides of the furnace, resulting in a large amount of monoxide. There is a problem that carbon is produced.

The purpose of the present invention is to address the above-mentioned drawbacks of the conventional technology, that is, to increase the high concentration of CO near the furnace side wall, which is a problem when performing low NO combustion such as two-stage combustion and in-furnace denitrification combustion, and to increase NO, The object of the present invention is to provide a combustion device that can reduce the amount of fuel without causing any damage.

In order to achieve the above object, the present inventors conducted various studies on the combustion state and CO generation state when combustion is performed by giving a swirling flow to the flame of each stage burner. That is, FIGS. 7 and 8 show the planar shapes of the flame and the second stage airflow when the airflow is given a rightward rotation by the air register. In the burner area shown in FIG. 7, all the flames except the two flames at the ends facing the side walls 8 are promoted to mix with the flames (including air) on the opposite side and both sides, so that unburned matter ( Although the generation of mainly CO) is suppressed to a relatively low level, the two flames moving towards the side walls 8 generate a relatively large amount of CO due to the lack of combustion air and poor mixing in the furnace.
It was found that O was being generated. As a result, a high CO region exists near both side walls in Fig. 7, and at the upper air port, there is little supply of second stage air to the vicinity of both side walls 13 in Fig. 8, and the mixing is not sufficient. However, the high concentration of CO generated in the burner zone is not sufficiently oxidized, leaving the 00 distribution in this area and leaving it in the cooling area (boiler coil section).
K rushes in, and after that it flows in a laminar state to the outlet of the economizer without being oxidized, so the temperature is almost the same as the outlet of the furnace.
It was found that the 0 distribution was maintained and the CO level was high overall.

Figure 9 shows the 00 distribution of the economizer outlet duct (in the figure The numbers indicate the results of measuring pI'n), which show a high CO concentration near both side walls.

The present invention has been made based on the above findings, and provides a combustion device including a burner facing a front wall and a rear wall and an air port on the upper part of the burner. Furthermore, an auxiliary air port is provided near the side wall, and the air supply port of the auxiliary air port is disposed toward the side wall. Typically, in the invention, four auxiliary air ports having the same diameter as the oil or a diameter smaller than the others are provided further near the side wall than both ends of the air port, and the swirling direction of the air is bent toward the side wall. The arrangement of nozzles improves the supply and mixing of air near the side walls.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 10 is a sectional view of a furnace burner section showing an embodiment of the present invention, and FIG. 11 is a sectional view of an air port section immediately above the furnace burner section. This device is similar to burner sections A, B, and C of a conventional furnace.
In the case where a two-stage air inlet (air port) 4 is provided at the top of the stage, directly above the burner on the front and rear walls of the furnace, the air port 4
Furthermore, four auxiliary air ports 14 and 15 are arranged between both outer sides of the furnace and the furnace side walls 8, and the diameter of these ports is the same as or smaller than the diameter of the air port 40, and a two-stage air inlet swirl flow is provided. By creating an air register structure, the injected air can be given arbitrary swirl, and the direction of the injected air flow can be bent toward both side walls by interaction with the combustion gas flow rising from below, and the air can be directed toward the side walls. In other words, each burner 3 is equipped with an air register, and the air swirl direction is adjusted so that it is all to the right. Furthermore, the air ports 4 directly above these burners are also adjusted to have the same air swirl direction. In the present invention, auxiliary air ports (hereinafter sometimes referred to as additional air ports) 14 and 15 are further provided near the side walls of the air ports on both side walls 8, and only one of the air ports 15 is opposed to the other air port 14. The configuration is such that all of the airflow from the additional air port turns toward the side wall 8 by giving a reverse left turn.

Figure 12 shows the results of investigating the effect of the additional air port diameter and air register opening on the CO reduction rate in a model furnace with the burner and air port arrangement and rotation direction shown in Figures 10 and 11. This shows that. In the figure, 16.17 and 18 indicate the CO reduction rate when the air register opening degree is 30, 50 and 100%, respectively.

This result shows that for all air register opening degrees, a good CO reduction rate can be obtained when (additional air port 14.150 caliber)/(conventional air port 40 caliber) is 1 or less. At this time, the No. concentration after exiting the furnace was 80 to 83, with almost no change. Therefore, additional airport 14
．． It can be said that the 150 caliber can best demonstrate its function when the diameter is the same as or smaller than the conventional air port 40 caliber. Regarding the air register opening,
Although there is an optimum value showing the highest CO reduction rate around 50 inches, it can be adjusted according to the situation in an actual machine.

According to the above embodiment, additional air ports with the same or smaller diameter than other air ports are provided near the side wall of the furnace, and the air register is designed to rotate in the direction in which the air flows from these additional air ports. By supplying all of the fuel toward the side wall and promoting mixing, the Co (unburnt) level can be reduced without changing the NO level.

As described above, according to the present invention, air is actively supplied to the vicinity of the furnace side wall, where conventionally the CO concentration was high, and mixing is promoted, thereby suppressing the high level of CO in this area and improving the NO process. Overall, the exhaust CO concentration can be reduced, for example, by about 50 cm or more, compared to conventional methods, without affecting the CO level. Note that the device of the present invention can be manufactured in the same manner as conventional devices, and it is also easy to modify the current device.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a conventional combustion device (boiler device) equipped with a multistage burner, and Figs. 2, 3, 4, and 5 show the fuel in each stage in the first stage combustion device. 6 is a plan view showing the state of gas flow in the combustion apparatus; FIGS. 7 and 8 are plan views showing the conventional combustion state, and FIG. The diagram is
A cross-sectional view showing the Co concentration distribution at the outlet of the economizer of the boiler device,
Figures 10 and 11 are cross-sectional views of the burner section and air port section of a combustion device in an embodiment of the present invention, respectively, and Figure 12 is an air port diameter ratio and CO reduction explaining an example of the effects of the present invention. It is a graph showing the relationship with the rate. 1... Boiler equipment, 2... Wind box, 3... Burner (
part), 4...Airport (part), 5...Furnace, 6.
... Furnace front wall, 7... Furnace rear wall, 8... Furnace side wall,
14.15...Auxiliary airport. Agent Patent Attorney Takeshi Kawakita Feature Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] (1) In a combustion device equipped with burners facing the front and rear walls and an air port above them,
, , an auxiliary air port is provided further near the side wall than the end of the upper air port, and the auxiliary air port σ
A denitrification combustion device characterized by having an air supply port facing the side wall. (2. Claim 1 is characterized in that opposing auxiliary air ports are provided near both walls of the air port, and the air supply ports thereof are arranged so as to give mutually opposite turning directions. Denitrification combustion equipment.