JPH06159633A - Burner - Google Patents

Abstract

PURPOSE:To obtain a burner wherein it is possible to execute a lean-burn with a stable condition with respect to a whole burner by a suppressability of a quantity of NOx as less as possible that is generated in a main combustion and a pilot flame, and by a good and stable formation of a pilot flame. CONSTITUTION:A burner that composes an axial direction edge portion of a tube 3 into which mixed gases g for combustion are supplied, as a flame opening 2 against a combustion flame, is provided with a perforated plate 5 having a permeability of the mixed gases for combustion on the whole face of the axial direction edge portion of the tube 3, and there is arranged a circular partition plate 6 that divides a combustion flame 4 formed on the flame opening 2 at an axial direction outer side of the perforated plate 5 in a tube axial direction into a main combustion flame 40 at a central side of, the tube and a pilot flame 41 formed around a periphery portion of the main combustion flame 40. Besides, at an upper stream side of a pilot nozzle portion 9 there is mounted a flow quantity regulating portion 7 which suppresses a quantity of the mixed gases g for combustion which executes a flow migration to a pilot nozzle portion 9 where the pilot flame 41 is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrial burner,
More specifically, it relates to a burner in which an axial end of a pipe to which a mixed gas for combustion is supplied is configured as a flame port for a combustion flame.

[0002]

2. Description of the Related Art Recently, NOx generated from combustion equipment has been regarded as a problem due to environmental pollution and the like, and a lean burn method has been proposed as a method for realizing low NOx for a burner. This is a method of suppressing the NOx generation amount by burning with a large air ratio and lowering the combustion temperature.
In a burner having a simple single-flame nozzle construction, it is difficult to obtain stable combustion if the combustion is performed at a high air ratio. Therefore, the pilot flame holding method is used as one of the countermeasures. That is, the outer periphery of the main combustion flame (lean mixed gas) is a flame holding pilot gas (low air ratio-not lean).
The pilot gas is always combusted, and the main combustion flame is forcibly ignited for stable combustion.

[0003]

However, in the burner having this structure, the NOx generation amount from the main combustion is small because it is a lean combustion, but the pilot portion is not a lean combustion, so the NOx generation amount is large. Therefore, it is possible to commonly use the lean gas supplied to the main combustion section as the combustion gas for the pilot, but for example, by providing a partition plate on the outlet side of the flame port, the main combustion flame on the center side and its In the case where a pilot flame is formed in the peripheral portion, the amount of jetting on the pilot side is too large to ensure a stable combustion state of this flame.

Therefore, the object of the present invention is to suppress the amount of NOx generated from the main combustion and the pilot flame as low as possible, and the pilot flame is formed satisfactorily and stably, resulting in lean combustion of the entire burner. To obtain a burner that can be performed in a stable state.

[0005]

To achieve this object, the burner according to the present invention, in which the axial end of the pipe to which the gas mixture for combustion is supplied is configured as a flame port for combustion flame, has the following features. A perforated plate through which the mixed gas for combustion is permeable is arranged over the entire axial end portion of the pipe, and the combustion flame formed at the flame port is formed on the outer side in the axial direction of the perforated plate in the pipe axial direction. An annular partition plate that separates the main combustion flame on the tube center side and the pilot flame formed around the main combustion flame is provided to suppress the amount of combustion mixed gas advancing to the pilot nozzle where the pilot flame is formed. The flow rate adjusting unit is provided on the upstream side of the pilot nozzle section, and the operation and effect are as follows.

[0006]

In other words, the burner of the present application employs a structure in which a perforated plate is provided at the axial end of the tube forming the flame port, and a combustion flame is formed at the downstream side portion of the perforated plate.
Then, the combustion flame is divided into a main combustion flame and a pilot flame formed around the main combustion flame by the partition plate. Further, a flow rate adjusting section is provided to suppress the flow rate of the mixed gas for combustion advancing to the pilot nozzle section where the pilot flame is formed. Therefore, the pilot flame is formed at a comparatively low flow rate, and even if it is in the lean combustion state, the flow velocity is reduced, so that it is possible to perform stable and constant combustion. As a result, ignition energy is supplied from the pilot flame in the stable combustion state to the main combustion flame in the entire burner, and stable combustion of the main combustion flame can be achieved.

[0007]

Therefore, the main combustion flame and the pilot flame are maintained in a lean combustion state to suppress the generation amount of NOx,
It was possible to obtain a burner capable of obtaining stable combustion. Further, in this configuration, the combustion area of the pilot nozzle can be increased as compared with the case where only the partition plate is simply provided, so that it becomes easy to make minute adjustments of the gas flow rate flowing to the pilot. As it came to be able to obtain a stable combustion flame. On the other hand, in the case of similarly forming a pilot flame, it is necessary to keep the flow rate of the pilot gas to a necessary minimum (ex. 1/20 or less of the main combustion gas) in order to stably generate the pilot combustion. However, it is possible to provide only the partition plate and perform the same adjustment as in the present application, but it is difficult to process the partition plate and the inner wall portion of the burner, and deviation of the position of the partition plate easily occurs. It is not practical because the ejection speed of the flame tends to be uneven.

[0008]

Embodiments of the present application will be described with reference to the drawings. FIG. 1 shows a vertical cross-sectional view of the vicinity of the flame port 2 in the lean burner 1 of the present application. This lean burner 1 is configured such that an axial end of a pipe 3 to which a mixed gas g for combustion is supplied is configured as a flame port 2 for a combustion flame 4, and the pipe 3
A porous plate (specifically, a metal foam) 5 through which the mixed gas for combustion g can permeate is arranged over the entire surface slightly invading from the pipe end in the vicinity of the axial end portion of the. And
A ring-shaped partition plate 6 is arranged on the upper surface (burner outlet side) of the metal foam 5, and a ring-shaped baffle plate 7 having a diameter different from that of the partition plate 6 is arranged on the lower surface (upstream side). The partition plate 6 divides the combustion flame 4 formed in the flame opening 2 into a main combustion flame on the center side of the tube (a flame opening portion corresponding to this combustion flame is called a main combustion nozzle portion 8) 40 and a main combustion flame 40. It has a role of partitioning into a pilot flame (a flame nozzle portion corresponding to this combustion flame is called a pilot nozzle portion 9) 41 formed in the peripheral portion, and the baffle plate 7 mentioned above is the inner diameter of the partition plate 6. The inner diameter is larger than the inner diameter, and the inner wall 30 is in contact with the inner wall 30. Therefore, the gas supplied to the pilot nozzle portion 9 enters from the inside of the baffle plate 7, penetrates the metal foam 5 and escapes to the outside of the partition plate 6, and the pressure loss between them allows fine adjustment of the pilot gas flow rate. It will be possible. The flow rate adjusting unit is configured in this way.

An actual dimensional relationship of the lean burner 1 will be shown. Tube 3 Outer diameter D1 144mm Partition plate 6 Outer diameter D2 130mm Inner diameter D3 110mm Baffle plate 7 Outer diameter D4 140mm Inner diameter D5 120mm Pilot flame width 5mm Metal foam wall thickness 10mm

When the lean burner 1 is burned, the lean mixed gas g whose air-fuel ratio λ is adjusted to about 1.5 is supplied and burned. In the combustion state, the ignition energy is stably supplied to the main combustion flame 40 from the pilot flame 41 formed on the peripheral portion of the main combustion flame 40, and the lean combustion is stably generated.

Example of application of lean burner Applied to a boiler of about 80,000 Kcal / h Air-fuel ratio λ = 1.1 to 1.5 NOx generation amount 30 ppm or less (O ₂₀ %) (Allowable maximum standard 60 ppm) CO generation amount ppm Turndown ratio 8: 1 or more

[Other Embodiment] Another embodiment of the present application will be described below. Regarding the configuration of the flow rate adjusting unit, since the purpose is to adjust the flow rate advancing to the pilot nozzle unit 9, the following configuration may be considered. (A) As shown in FIG. 2, the density of the perforated plate 5 is set between the pilot nozzle portion 9 at the upstream side portion of the pilot nozzle portion 9 and the main combustion nozzle portion 8 at which the main combustion flame is formed.
The more closely you set it, the more you configure. (B) As shown in FIG. 3, the density of the perforated plate 5 is constant over the entire surface, and the upstream side part of the pilot nozzle part 9 and the upstream side part of the main combustion nozzle part 8 where the main combustion flame is formed. Thus, the thickness in the axial direction is set thicker on the pilot nozzle 9 side.

Further, in the above-mentioned embodiment, the main combustion flame is a normal single flame mouth flame, but a new inner pipe 300 having the same pipe axis as the pipe 3 is provided in the pipe 3 constituting the burner. A low-air-ratio combustion gas, which is arranged to form the main combustion flame as an annular flame, and which supplies the low air-ratio combustion gas gl with a low air ratio to the inner peripheral portion of the main combustion flame from the inner pipe 300. The supply nozzle 301 may be provided. In this case, the gas g1 having a low air ratio is supplied from the low air ratio combustion gas supply nozzle 301, and this gas g1 causes slow combustion in the reducing atmosphere, so that the NOx generation amount is suppressed and the burner as a whole is suppressed. The air-fuel ratio can be adjusted to a value close to the theoretical air ratio, and the burner efficiency can be increased.

Further, in the above-mentioned embodiment, the example in which the metal foam 5 is adopted as the perforated plate is shown, but a member such as a ceramic perforated plate which is resistant to the flow with respect to the mixed gas for combustion. It can be anything.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a burner of the present application.

FIG. 2 is a diagram showing another embodiment of a flow rate control unit.

FIG. 3 is a diagram showing another embodiment of the flow rate control unit.

FIG. 4 is a diagram showing a configuration of a burner provided with a low air ratio combustion gas supply nozzle.

[Explanation of symbols]

 2 Flame port 3 Tube 4 Combustion flame 5 Perforated plate 6 Partition plate 7 Baffle plate 8 Main combustion nozzle section 9 Pilot nozzle section 40 Main combustion flame 41 Pilot flame 300 Inner tube 301 Low air ratio combustion gas supply nozzle g Combustion mixed gas g1 Low air ratio combustion gas

Claims (5)

[Claims] 1. A burner in which an axial end of a pipe (3) to which a mixed gas for combustion (g) is supplied is configured as a flame port (2) for a combustion flame, and the shaft of the pipe (3). A perforated plate (5) through which the combustion mixed gas (g) can pass is arranged over the entire end in the direction, and the flame is provided on the axially outer side of the perforated plate (5) in the tube axial direction. An annular flame that divides the combustion flame (4) formed at the mouth (2) into a main combustion flame (40) on the tube center side and a pilot flame (41) formed around the main combustion flame (40). A partition plate (6) is provided, and a flow rate adjusting unit for suppressing the amount of the combustion mixed gas (g) advancing to the pilot nozzle unit (9) in which the pilot flame (41) is formed is provided as the pilot nozzle unit (9). ) A burner installed on the upstream side. 2. The perforated plate, wherein the flow rate adjusting part has an annular baffle plate (7) whose inner diameter is larger than the inner diameter of the partition plate (6) while the outer peripheral part is in contact with the inner wall of the pipe (3). The gas mixture (g) for combustion is provided on the upstream side of (5), and the baffle plate (7) is introduced into the pipe (3) from the upstream side.
2. The burner according to claim 1, wherein the burner is diverted to the inner diameter side and admitted to the pilot nozzle portion (9). 3. The density of the perforated plate (5) is set to the upstream side portion of the pilot nozzle part (9) and the main combustion flame (4).
0) is formed on the upstream side portion of the main combustion nozzle portion (8), the density is set closer to the pilot nozzle portion (9) side,
The burner according to claim 1, wherein the flow rate adjusting unit is configured. 4. A main combustion nozzle part in which the density of the perforated plate (5) is constant over the entire surface and the upstream side part of the pilot nozzle part (9) and the main combustion flame (40) are formed. The burner according to claim 1, wherein the upstream side portion of (8) and the pilot nozzle portion (9) are configured such that the axial thickness of the burner is thicker toward the pilot nozzle portion (9) side. 5. An inner tube (300) is arranged in the tube (3) with the same tube axis as the tube (3) to form the main combustion flame (40) as an annular flame. A low air ratio combustion gas supply nozzle (301) for supplying a low air ratio combustion gas (g1) whose air ratio is adjusted to be low from the inner pipe (300) is provided in an inner peripheral portion of the main combustion flame (40). The burner according to any one of claims 1 to 4.