JPS6363813B2 - - Google Patents

Description

Detailed Description of the Invention The present invention relates to a device for supplying secondary air for an after-air port to completely burn unburned components in burner combustion exhaust gas, and in particular, a device for supplying secondary air for an after-air port to completely burn unburned components in burner combustion exhaust gas, and in particular, a device for supplying secondary air for an after-air port to completely burn unburned components in burner combustion exhaust gas. The present invention relates to a structure of a swirler device for supplying secondary air with variable inclination angle.

Chlorine oxide (hereinafter referred to as
The following methods have been adopted in combustion equipment such as boilers to reduce NOx (referred to as NOx). In other words, (1) the two-stage combustion method, (2) the use of low NOx burners, (3) the mixing of exhaust gas, etc., and more recently, the incomplete combustion of certain burners, and the reduction effect of the resulting intermediate products. A method of reducing NOx has been adopted. However, all of these methods cause incomplete combustion when viewed from the viewpoint of combustion, and the combustion efficiency decreases. For this reason, during low NOx operation, efforts are usually made to reduce NOx while also improving combustion efficiency by combining several of the above methods.

For example, even in the two-stage combustion method, in addition to performing low-oxygen combustion in the first stage combustion, methods such as introducing exhaust gas to lower the flame temperature are often used in combination. In this case, as a matter of course, a considerable amount of unburned matter such as unburned carbon is generated in the first stage combustion. For this purpose, an opening is provided in the furnace wall to supply secondary air to the wake of the combustion gas flow from the first stage combustion section, and the secondary air from this opening is allowed to flow into the furnace to remove unburned matter in the combustion gas. It's burning.

(This opening is referred to as an after-air port.) Conventionally, no special consideration has been given to the device installed in this opening to enhance the input of secondary air throughflow into the furnace in response to the combustion load.

In addition, in recent low NOx combustion methods, an air ratio
A burner (auxiliary burner) with a low air ratio of 0.6 etc. is installed,
A method is employed to remove NOx from the combustion gas by using reducing intermediate products generated by the auxiliary burner.

Also in this case, since a low air ratio burner is used, there are many unburned components in the exhaust gas, so it is necessary to provide the above-mentioned after-air port and supply secondary air to sufficiently burn the unburned components. be.

On the other hand, ordinary burners and low air ratio burners are built integrally with the burner and supply secondary air from around the burner to surround the burner flame to improve mixing with the fuel and ensure good combustion even when the combustion load changes. A burner structure with fixed blades is adopted.
(For example, the invention of JP-A-53-145130, JP-A-54-
Invention of Publication No. 13017).

However, since all of these use fixed swirling vanes as means for imparting swirling force to the secondary air, they create a combustion state appropriate for the amount of fuel that corresponds to changes in the boiler load. Sufficient ejection energy and swirling energy will not be given, and the combustion rate of unburned matter will decrease compared to the amount of air supplied, and soot and dust and unburned matter will increase.

An object of the present invention is to eliminate the above-mentioned problems and provide a swirler device for supplying secondary air for an after-airport, which can give sufficient injection energy and swirling energy to the air regardless of the amount of secondary air supplied. There is a particular thing.

In short, this invention uses a swirler (swirler) in the throat section for secondary air supply provided at the after air port.
The swirler blades are arranged so that the blades of the swirler can be rotated to vary the mounting angle, that is, the inclination angle of the blade surface with respect to the direction of combustion air flow.

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show the structure of a swirler device with rotating blades according to the present invention. In the figure, 1 is a support shaft that supports the swirler body, and inside the support shaft 1 there is a rotating shaft 2 located on the center axis of this support shaft 1.
is placed. A parent bevel gear 3 is provided at the furnace side end of the rotating shaft 2 (on the right side in the figure). One side support shaft 1
A duct 5 attached to a support shaft 1 by a strut 4 is arranged at the end of the furnace side, and within this duct 5 a plurality of blades 6 are arranged radially around the support shaft 1. The configuration of this blade 6 will be explained using the blade 6a shown in FIG.
is formed to rotate freely relative to the duct 5. On the other hand, an adjustment shaft 9 is fixed to the end of the blade 6a on the support shaft side.The adjustment shaft 9 passes through the support shaft 1, and at its tip there is a child bevel gear 10 that engages with the parent bevel gear 3. is installed. The other blades 6 have the same structure as the blade 6a described above, and the rotation of the rotating shaft 2 is transmitted to the blade 6 via the parent bevel gear 3, each child bevel gear 10, and each adjustment shaft 9, and supports each blade. The inclination with respect to the air flow parallel to the axis of the shaft 1, that is, the inclination angle of the blade surface with respect to the central axis of the rotating shaft 2 is adjusted.

Next, the rotating shaft 2 and the supporting shaft 1 are inserted through the wall surface 11a of the wind box 11 and protruded to the outside, and the rotating shaft 2 is connected to the angle adjuster 20.
The end of the rotating shaft 2 is bent approximately 90 degrees and connected to the regulator connection part 2.
The end of the regulator connecting portion 2a is rotatably fitted into the pin 21. 22 is pin 2
This spring inserts the tip end of the pin into the engagement hole 23 via the flange 21a formed in 1. When the operator wants to change the inclination angle of the blade 6 with respect to the support shaft axis, the operator first pulls the handle 24 in the X direction to release the engagement between the pin 21 and the engagement hole 23, and then pulls the handle 24. The blade 6 is moved in the X' or Y' direction to engage another engagement hole and the pin to change the inclination angle α of the blade 6 with respect to the burner axis (third
(see figure). Note that when the engagement between the engagement hole 23 and the pin 21 is completed, the handle 24 is returned to the Y direction by the spring 22.

FIG. 4 shows a state in which the above-described swirler device with rotating blades is arranged in a secondary air supply section of a boiler. The maximum diameter D of the air throat 14 for two-stage combustion formed in the furnace wall 15 of the boiler is
It is determined based on the maximum flow rate of secondary air A injected from. The aforementioned swirler with rotating blades is placed in the center of this throat, and most of the secondary air A for two-stage combustion normally passes through the throat 14 and is given a swirling force by the blades 6 of the swirler. It is injected into the furnace 16. Note that a part of the secondary air flows between the wall surface of the duct 5 and the throat 14 surrounding the swirling air flow due to the swirler, and this swirling force is not reduced. In this case, when the boiler load decreases or the secondary air amount decreases due to a change in the two-stage combustion ratio, the inclination angle α of the blade 6 is increased to prevent the swirling energy of the secondary air from decreasing. Furthermore, if the amount of secondary air supply decreases to the extent that sufficient energy cannot be obtained even with this tilt angle adjustment, the angle α is brought to approximately 90° and the swirler is fully closed. As a result, the secondary air is injected through the narrow annular space between the duct 5 and the throat 14 of the swirler device, so that high injection energy can be obtained.

By implementing this invention, it is possible to always provide sufficient swirling force or injection force to the air supplied into the furnace regardless of the air flow rate, and the effect of complete combustion of unburned components in low NOx combustion. can be given.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a swirler device with rotating blades according to the present invention, FIG. 2 is a perspective view of FIG. 1, and FIG.
The figure is a perspective view of the inclination angle adjuster, and FIG. 4 is a longitudinal sectional view including the throat of the swirler device for supplying secondary air. 1... Support shaft, 2... Rotating shaft, 3... Main bevel gear, 5... Duct, 6... Vane, 9... Adjustment shaft,
10... Child bevel gear, α... Inclination angle.

Claims (1)

[Scope of Claims] 1. In a device that supplies secondary air for an after-air port to completely burn unburned content in burner combustion exhaust gas, a plurality of blades are installed in the throat of the secondary air flow path radially from the throat center line. a driving device for changing the angle of inclination of the surfaces of the plurality of blades with respect to the air flow direction, and surrounding the outer ends of the plurality of blades; A swirler device for supplying secondary air characterized by being provided with a duct. 2. A rotating shaft is arranged within the supporting shaft so as to be located on the same axis as the supporting shaft, and a parent bevel gear is provided at the furnace side end of the rotating shaft, and the plurality of blades are arranged at one end. is attached to the duct so that it can rotate freely, and a child bevel gear that engages with the master bevel gear via an adjustment shaft is attached to the other end, so that the inclination angle of each blade with respect to the gas flow direction can be adjusted by rotating the rotating shaft. A swirler device for supplying secondary air according to claim 1, characterized in that it is configured to be modified.