JP3309014B2 - Method of charging air for two-stage combustion in a two-stage combustion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for charging air for two-stage combustion in a wall combustion device such as a boiler device.

[0002]

2. Description of the Related Art A boiler apparatus is required to reduce NOx and CO in order to cope with environmental problems, while it is required to increase efficiency in order to cope with a request to reduce running costs. As one method for simultaneously satisfying these requirements, a two-stage combustion method has been conventionally known. In this two-stage combustion method, combustion air is supplied in two stages,
In the first stage (burner portion), combustion is performed at an air ratio of 1 or less, and insufficient air is supplied from the second stage, which is a subsequent stream, to complete combustion.

FIG. 4 shows an example of a conventionally known two-stage combustion type boiler furnace. In this figure, 1 indicates a boiler furnace, 1a indicates before the can, and 1b indicates after the can. A plurality of burners 2 are respectively set in a vertical direction and a horizontal direction (furnace width direction) in front of the can 1a and rear of the can 1b, and a wind box 3 is provided around an outer surface of the burner setting portion. I have. Above the can 1a and after the can 1b (on the downstream side), an inlet 4 for the two-stage combustion air is provided, and also around the outer surface of the air inlet 4.
A wind box 5 is provided. The burner 2 is supplied with fuel pumped from a fuel supply device 7 via a fuel supply pipe 6, and the wind box 3 is supplied with combustion air pumped via an air supply pipe 8. On the other hand, to the wind box 5 provided around the two-stage combustion air inlet 4, the combustion air pumped through the air supply pipe 9 is supplied. Each of the air supply pipes 8 and 9 has
Dampers 10 and 11 are provided, respectively.
By adjusting the opening degrees of 0 and 11, the amount of combustion air supplied to the wind boxes 3 and 5 can be adjusted.

As described above, in this type of boiler, in order to suppress the generation of NOx (nitrogen oxide),
By adjusting the opening of the damper 10, the amount of combustion air supplied from the burner is adjusted to be less than the theoretical amount of air, and by adjusting the opening of the damper 11, the downstream two-stage combustion air inlet 9 is adjusted. Is adjusted so that the amount of combustion air supplied from the furnace becomes equal to or greater than the theoretical amount of air at the furnace outlet. However, conventionally, in this type of boiler apparatus, there has been no operation method of providing a deviation in the amount of combustion air to a plurality of wind boxes arranged in the furnace width direction. The amount of air supplied to is adjusted to be substantially constant.

[0005]

However, according to the above-described conventional method for charging combustion air, near the two-stage combustion air charging port 4, as shown in FIG. Insufficient air volumes 12 occur at the four corners and the side wall portions. Reference numeral 14 in the figure indicates an excess air region in the furnace 1. Insufficiency in the amount of combustion air increases the unburned content, lowers the efficiency of the entire furnace, and causes the generation of NOx and CO (carbon monoxide). Therefore, in the combustion method in which the two-stage combustion is performed, an important technical problem is how to supply combustion air to the four corners and side wall portions of the furnace 1 where the combustion gas rises.

SUMMARY OF THE INVENTION The present invention has been made to solve the above technical problem, and an object of the present invention is to improve the mixability of air and combustion gas for two-stage combustion at the outlet of a furnace.
It is an object of the present invention to provide a method for charging air for two-stage combustion, which is excellent in economy and environment.

[0007]

SUMMARY OF THE INVENTION The present invention, in order to achieve the above object, comprises a plurality of burners to the furnace wall, and該Ba <br/> over the width of the furnace wall facing the downstream side of the Na in the combustion apparatus of the two-stage combustion method with the inlet of each air plurality of two-stage combustion in a direction, before the Kito inlet flow rate of the two-stage combustion air supplied to the furnace is the inlet is arranged Of each furnace wall
Given deviation in the width direction and the opposite direction, and the structure that causes the two-stage combustion by Ri before Symbol furnace shear force of air supplied to generate a circulating flow of the two-stage combustion air from the respective inlet. Further, one of the furnace walls in which the inlets are arranged is one of the furnace walls.
From the center of one furnace wall and both ends of the other furnace wall.
The flow rate of the two-stage combustion air is adjusted at both ends of the one furnace wall.
And the two-stage combustion space supplied from the center of the other furnace wall.
The configuration is such that it is larger than the air flow.

As another means, in a two-stage combustion type combustion apparatus similar to the above, of the two-stage combustion air supplied into the furnace from the plurality of two-stage combustion air inlets, The two-stage combustion air supplied from the left half is given a counterclockwise rotation, and the two-stage combustion air supplied from the right half of the furnace is given a clockwise rotation.

[0009]

[Function] Changes the distribution of air for two-stage combustion in the furnace width directionTo
Circulating flow is generated by the shear force between the opposing jets.
To improve the mixability of the combustion gas and the two-stage combustion air.
In both cases, by adjusting the swirl force of the two-stage combustion air,
To supply combustion air evenly to the entire can.
You. In addition, the two-stage fuel injected from the two-stage combustion air inlet
This can also be achieved by imparting swirling air in a specific direction.
Similar tophenomenonCan be generated. Like,
When the mixing properties of the combustion gas and the two-stage combustion air are improved,
The amount of air for two-stage combustion can be reduced, and the combustion equipment
The inning cost can be reduced. Ma
When the combustion air is evenly supplied to the entire can, the air volume
Area is reduced or eliminated, and unburned fuel
Improvement of combustion efficiency and suppression of generation of CO, NOx, etc.
Can be planned.

[0010]

FIG. 1 shows a method for charging air for two-stage combustion according to a first embodiment. This figure is a horizontal cross-sectional view of the two-stage combustion air inlet stage of the combustion device, and the same reference numerals are given to the portions corresponding to FIG. 4 described above. The arrow 13 in the figure indicates that the furnace 1
Represents the two-stage combustion air jet supplied to the inside, and arrow 1
5 shows a circulating flow generated by the shear force of the two-stage combustion air jet 13. Note that the size of the arrow 13 is
Shows the flow rate of the two-stage combustion air.

As is apparent from FIG. 1, in this embodiment, four two-stage combustion air inlets 4 are provided in the furnace width direction, respectively, and a central portion of the front 1a of the can and both ends of the rear 1b of the can are provided. The amount of air supplied into the furnace from the two-stage combustion air inlet 4 is supplied into the furnace from the two-stage combustion air inlet 4 at both ends of the front 1a of the can and at the center of the rear 1b of the can. More than the amount of air.

According to the method for charging the two-stage combustion air, two opposite directions as shown in FIG.
A circulating flow 15 is created. The circulation flow 15 promotes mixing of the combustion gas and the two-stage combustion air. Further, since the jets 13 of the two-stage combustion air on both sides after the can are mixed with the combustion gas on the side wall portion, shortage regions of the combustion air are hardly formed on the side wall portion and the four corners, and unburned components are generated, Generation of CO and NOx can be suppressed.

FIGS. 2 and 3 show a method for charging the two-stage combustion air according to the second embodiment. FIG. 2 is a horizontal cross-sectional view of a two-stage combustion air inlet stage of the combustion device, and FIG. 3 is a front view seen from the air inlet direction, and portions corresponding to FIG. The same symbols are displayed. Arrow 17 in the figure indicates the flow of the combustion gas, and arrow 16 indicates the direction of the rotation given to the two-stage combustion air jet 13.

As shown in FIG. 3, in the present embodiment, of the two-stage combustion air introduced from the two-stage combustion air inlet 4, from the left half of the furnace 1 when viewed from the front of the air inlet. The input two-stage combustion air is given a counterclockwise rotation, and the supplied two-stage combustion air from the right half of the furnace 1 is given a clockwise rotation.

In this manner, the upward flow of the combustion gas 17 is promoted to rise in the central portion of the furnace 1 to increase the flow rate. On the other hand, in the vicinity of the side wall, the swirling flow forms a downward flow. The rise of the combustion gas 17 is suppressed. By this action, a strong flow of the combustion gas is generated in the central portion of the furnace that promotes the upward flow, and the two-stage combustion air jet 13 is bent toward the side wall as shown in FIG. For this reason, unlike the conventional example, it is difficult to form an insufficient area for combustion air in the side wall and the four corners, and it is possible to suppress the generation of unburned components and the generation of CO and NOx.

[0016]

According to the present invention, since the two-stage combustion air can be used under the minimum conditions and the unburned portion and CO can be reduced, the excess air amount is reduced in addition to the high efficiency by the unburned portion. Efficiency is expected to be increased, and there is an effect of reducing running costs.

[Brief description of the drawings]

FIG. 1 is a plan view showing a method for charging air for two-stage combustion according to a first embodiment.

FIG. 2 is a plan view showing a flow of two-stage combustion air in a furnace when a method for charging two-stage combustion air according to a second embodiment is applied.

FIG. 3 is a front view showing a method for charging two-stage combustion air according to a second embodiment.

FIG. 4 is a side view showing an example of a combustion device according to the related art.

FIG. 5 is a plan view showing a disadvantage of the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boiler furnace 2 Burner 3,5 Wind box 4 Two-stage combustion air inlet 6 Fuel supply pipe 7 Fuel supply device 8,9 Air supply pipe 10,11 Damper 12 Air shortage area 13 Two-stage combustion air flow 14 Air Excess area 15 Circulating flow 16 Swirling flow 17 Gas rising flow

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Takahiro Marumoto 3-36 Takara-cho, Kure-shi, Hiroshima Babcock-Hitachi Co., Ltd. Kure Research Institute (56) References JP-A-3-28624 (JP, A) JP-A-5-18510 (JP, A) JP-A-7-63306 (JP, A) JP-A-60-174408 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F23C 11 / 00

Claims (3)

(57) [Claims] [Claim 1 further comprising a plurality of burners to the furnace wall, and each該Ba <br/> over the width direction of the opposing furnace walls of the downstream side of the burner with a charging port of a plurality of two-stage combustion air in the combustion apparatus of the two-stage combustion method, before the Kito inlet of each furnace wall, wherein the inlet flow rate of the two-stage combustion air supplied to the furnace are arranged
Given deviation in the width direction and the opposite direction, characterized in that to generate a circulating flow of the two-stage combustion air to respective inlet the two-stage combustion by Ri before Symbol furnace shear force of the air supplied from the A method for charging air for two-stage combustion in a two-stage combustion device. 2. A furnace wall in which said inlets are arranged.
From the central part of one furnace wall and both ends of the other furnace wall
The flow rate of the supplied two-stage combustion air is controlled by the one furnace wall.
Two-stage fuel supplied from both ends and the center of the other furnace wall
The flow rate of the air for burning is increased.
2. A method for charging air for two-stage combustion in the two-stage combustion device according to 1 . 3. A two-stage combustion type combustion system in which a plurality of burners are provided on a furnace wall and a plurality of two-stage combustion air inlets are respectively provided in a width direction of the opposed furnace walls on the downstream side of the burner. In the device, among the two-stage combustion air supplied into the furnace from the plurality of two-stage combustion air inlets, the two-stage combustion air supplied from the left half of the furnace is given a counterclockwise rotation. A method for charging two-stage combustion air in a two-stage combustion device, wherein the two-stage combustion air supplied from the right half of the furnace is turned clockwise.