JPH0462309A - Low noise combustion method by two-step combustion of burner - Google Patents

Abstract

PURPOSE:To improve the combustibility and reduce ignition noise and combustion noise by a method wherein a supply air volume in the vicinity of a burner is kept not more than theoretical air volume, and the shortage portion is blown in to the central part of flame as secondary air from the furnace bottom at the bottom of a combustion chamber. CONSTITUTION:Primary air which is air-volume-adjusted to be not more than theoretical air by a primary air damper 5 passes through a wind box 3 and distributor 4, is mixed with fuel injected form a burner 2 and emitted. Then, the fuel burns in a combustion cone 14. In this case, since the primary air volume is reduced to be not more than theoretical air, outer flame burns mixing with air for combustion, but inner flame becomes unfavorable combustion area because by the primary air for combustion, air volume is not enough, and mixing is unfavorable. For this reason, secondary air which is air-volume-adjusted by a secondary air damper 6 is blown into the center of flame A from a secondary air blow-in part 10 on a furnace bottom 12 through a secondary air passage 7. By this secondary air, an air volume which is slightly more than the theoretical air volume required for combustion can be obtained, and therefore, complete combustion takes place. In addition, since the flow velocity in the vicinity of the distributor 4 becomes slower, the ignition noise and combustion noise become lower, and the combustibility becomes better. By this method, since complete combustion takes place, excellent flammability characteristic properties can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a low-noise combustion method using two-stage combustion in a burner installed in a combustion device such as a vertical water tube boiler.

[Prior Art and Problems to be Solved by the Invention] In the above-mentioned combustion apparatus, a factor that greatly affects the combustibility of the burner that burns fuel is the flow velocity of air near the baffle plate of the burner. That is, increasing the flow velocity near the current plate improves combustibility, but increases the ignition noise and combustion noise, and slowing it down lowers the ignition noise or worsens combustion, which are contradictory characteristics.

In the conventional technology, priority is given to combustibility among these conflicting characteristics, and therefore there is a problem in that the ignition noise and combustion noise become louder.

The present invention has been made in view of the above-mentioned points, and is a low-noise combustion method using two-stage combustion of a burner that has the above-mentioned contradictory characteristics and is capable of improving combustibility and reducing ignition noise and combustion noise. Our goal is to provide the following.

[Means to solve the problem]

In order to solve the above problems, the present invention, as shown in the drawings,
2 in front of the primary air damper (5) at the outlet of the blower (1).
A secondary air passage (7) is provided, and this secondary air passage (7)
A secondary air damper (6) is provided inside, and the primary air damper 5
), the amount of air supplied for combustion is set to be less than the theoretical amount of air, and the shortage is blown into the center of the flame from the bottom (12) of the furnace as secondary air.

[Effect]

The present invention performs a low-noise combustion method using two-stage combustion as described above. That is, by setting the primary air damper (5) to a theoretical air amount or less, the flow velocity of air in the vicinity of the burner baffle plate (4) can be slowed down, and ignition noise and combustion noise can be lowered.

In combustion, the flow velocity near the burner rectifying plate 4) is slow and the amount of air is less than the theoretical amount, so there is a lack of air in the center of the flame, resulting in a combustion failure area. By feeding the air, the amount of combustion air can be made slightly larger than the theoretical air required for complete combustion. Therefore, in conventional two-stage combustion, there is a method of bringing secondary air into contact with the external flame, but the effect of improving combustion is low and excess air is required, but the present invention can solve these problems.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a diagram showing a schematic structure of a vertical water tube boiler to which the low-noise combustion method using two-stage combustion of the present invention is applied. In the figure, 8 is a combustion chamber surrounded by a group of woodwinds 9;
The upper and lower ends of the woodwind group 9 can be connected to an upper header 15 and a lower header 16. At the bottom of the combustion chamber 8, a furnace bottom 12 made of refractory material is formed. A burner 2 is disposed in the upper part of the combustion chamber 8, and a rectifying plate 4 is disposed at the tip of the burner 2. Also,
A wind box 3 is disposed in the upper part of the combustion chamber 8, a primary air passage 13 is disposed connected to the wind box 3, and a combustion air passage is further connected to the tip of the primary air passage 13. A cone 14 is provided.

Reference numeral 1 designates an air blower, and a primary air damper 5 is provided at the outlet of the air blower 1, and is connected to the wind box 3. Further, a secondary air passage 7 is arranged before the primary air damper 5 at the outlet of the blower 1, and a secondary air passage 7 is provided in the secondary air passage 7.
A second air damper 6 is provided. In addition, the secondary air passage 7
The tip thereof is connected to a secondary air blowing section 10 formed approximately in the center of the hearth bottom 12.

In addition, in the figure, 11 is a chimney stand.

In the vertical water tube boiler having the above structure, the primary air damper 5
The primary air whose air volume is adjusted to be less than the theoretical air volume passes through the wind box 3 and the baffle plate 4, mixes with the fuel injected from the burner 2, and is emitted. The fuel is then combusted within the combustion cone 14. Here, the amount of primary air is reduced below the theoretical amount of air, so the outer flame mixes with the combustion air and burns, but the inner flame is caused by insufficient air amount and poor mixing with the primary combustion air. It becomes a combustion failure area. Therefore, the secondary air whose air volume has been adjusted by the secondary air damper 6 is passed through the secondary air passage 7, and the flame A
Blow into the center of. The amount of secondary air, together with the amount of primary air, is set to be slightly larger than the theoretical amount of air required for combustion.

By employing the combustion method described above, complete combustion is achieved because the secondary air provides an air amount slightly larger than the theoretical air amount required for combustion, and the flow velocity near the rectifier plate 4 is Since it is small, the ignition noise and combustion noise are low, resulting in a combustion method with excellent combustibility.

In the above embodiment, the secondary air blowing section 10 is provided at one location approximately at the center of the hearth bottom 12, but there may be a plurality of secondary air blowing sections. In short, the number of secondary air blowing parts does not matter as long as the structure is such that the secondary air is branched from the blower 1 and blown toward the flame center.

〔Effect of the invention〕

As explained above, the present invention makes it possible to reduce the flow velocity near the current plate by reducing the amount of air near the current plate to less than the theoretical air amount, thereby reducing ignition and combustion noise. It can be lowered.

In addition, complete combustion can be achieved by blowing secondary air from the bottom of the furnace into the poor combustion area due to lack of air in the center of the flame, resulting in excellent combustion characteristics.

Also, as a result, low N due to two-stage combustion.

You can also get the X effect.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a schematic configuration of a vertical water tube boiler to which the low-noise combustion method using two-stage combustion of the present invention is applied. In the figure, 1... blower, 2... burner, 3...
・Wind box, 4... Rectifier plate, 5... 1
Secondary air damper, 6... Secondary air damper, 7...
Secondary air passage, 8... combustion chamber, 9... water tube group,
10... Secondary air blowing section, 11... Chimney stand, 1
2... Furnace bottom, 13... Primary air passage, 14...
... Combustion cone, 15... Upper header, 16...
・Lower pipework. Patent applicant: Ebara Corporation

Claims (1)

[Scope of Claims] In a combustion device in which a burner is provided in the upper part of a combustion chamber and a furnace bottom is formed with a refractory material in the lower part, the amount of air supplied in the vicinity of the burner is set to be less than or equal to the theoretical air, and the shortage is filled in the combustion chamber. 2 of a burner characterized by blowing secondary air into the center of the flame from the bottom of the furnace.
A low-noise combustion method using staged combustion.