JP2669953B2 - Gas burner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas burner used for an absorption refrigerator, an absorption heat pump, a boiler and the like.

[0002]

2. Description of the Related Art In recent years, reduction of nitrogen oxides (hereinafter referred to as NOx) discharged from boilers installed in factories or buildings has become a major issue. Even in the gas burner installed in the boiler, low NOx in exhaust gas is a problem, and for example, in the actual Kaihei 2-140.
In Japanese Patent Laid-Open No. 122-122, a gas fuel injection hole is formed at the tip of a gas nozzle so as to eject gas fuel in an inclined direction, and a plurality of air ports 4a, 4b for supplying combustion air to the peripheral portion of the gas nozzle. Disclosed is a gas burner in which the gas fuel injection holes and the outermost air ports 4b are positioned so that the phases thereof overlap in the circumferential direction of the nozzle.

[0003]

In the above prior art, since the gas fuel injection hole and the outermost air port overlap, a flame holding region is formed and the gas fuel injection hole is discharged. The air port 4a where the gas pressure is low,
Although the secondary air flowing out from 4b improves the mixing with the gas, since the air port 4b is formed over almost the entire surface of the flame holding plate, the combustion temperature may rise significantly and the NOx concentration may increase. There is. Further, when the air port 4b is not formed, the combustion is not completed particularly in the low combustion region, the incomplete combustion is likely to occur, and unburned gas may be generated.

An object of the present invention is to maintain flame holding performance, suppress combustion temperature, and suppress NOx concentration.

[0005]

In order to solve the above-mentioned problems, the present invention provides a first invention, in which a first flame holding plate is connected to the tip and a plurality of them are provided on a peripheral wall in the vicinity of the first flame holding plate. Of the second nozzle having a gas nozzle having a gas ejection hole, a plurality of combustion secondary air passages formed by dividing the periphery of the gas nozzle, and a combustion primary air passage formed between the outer periphery of the gas nozzle provided at the center. A flame holding plate and a burner cone in which the second flame holding plate is connected to the inner wall are provided, and the first flame holding plate and the second flame holding plate are arranged substantially parallel to each other so that the both plates are substantially uniform. Where X is a distance and Y is a gas ejection hole, Y ≦ X ≦ 5Y is satisfied, the outer diameter of the first flame holding plate is made larger than the inner diameter of the second flame holding plate, and the combustion temperature is increased. It is intended to provide a gas burner in which the NOx concentration is reduced and the NOx concentration is reduced.

Further, the second flame holding plate is provided with a plurality of air holes which are substantially parallel to the first flame holding plate and near the gas ejection holes so as to improve the mixing of the combustion gas and the secondary air. To prevent the generation of unburned gas.

[0007]

When the gas burner is burning, the fuel gas flowing out from the gas ejection holes 8 mixes with the primary air flowing out from the primary air passage 11A and the first flame holding plate 7 and the second flame holding plate 10 are mixed. Flows along the second flame stabilizing plate 10 from a substantially uniform interval of
The flame is widely dispersed, the combustion temperature is suppressed by the cooling effect of the dispersion, and the generation of NOx can be reduced.

Further, the mixing of the fuel gas and the primary air is promoted by the secondary air flowing out from the air hole 12 so that the combustion can be completed, and the air hole 12 is located in the vicinity of the gas ejection hole 8. As a result, it is possible to prevent the dispersion and splitting of the flame formed from being hindered by the secondary air flowing out from the air holes 12, and to reduce the production of NOx.

[0009]

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

FIG. 1 is a sectional view of a low NOx gas burner, and FIG. 2 is a front view of the gas burner 1 shown in FIG.

In FIGS. 1 and 2, the gas burner 1 mixes the fuel gas supplied from the gas supply pipe 2 and the combustion air supplied from the blower 3 and burns them. The gas burner 1 has a cylindrical gas nozzle 4,
It is composed of a burner cone 5, a burner flange 5A, a wind box 5B, a pilot burner 6, and the like.

Reference numeral 7 denotes a circular first flame holding plate D provided at the tip of the gas nozzle, and the vicinity of the first flame holding plate 7, that is,
A plurality of gas ejection holes 8 are formed at the tip of the gas nozzle 4 at equal intervals in the nozzle circumferential direction. Reference numeral 10 is a circular second flame holding plate provided at the tip of the burner cone 5. Here, a primary air passage 11A is provided between the gas nozzle 4 and the opening 10A formed in the center of the second flame stabilizing plate 10. Further, when the second flame holding plate 10 and the first flame holding plate 7 are substantially parallel to each other and X is a substantially uniform interval between the both plates 10 and 7, and the diameter of the gas ejection hole 8 is Y, When the diameter of the gas ejection holes 8 is, for example, 5 mm so that Y ≦ X ≦ 5Y is satisfied, a uniform interval of, for example, 10 mm is provided between the second flame holding plate 10 and the first flame holding plate 7. There is. Reference numeral 11B denotes a plurality of secondary air passages formed in the peripheral edge of the second flame stabilizing plate 10. As shown in FIG. 2, for example, six secondary air passages 11B include six gas ejection holes 8 and a gas nozzle circumferential direction. Do not match in.

Reference numeral 12 is an air hole formed in the second flame holding plate 10. These air holes 12 are in the vicinity of the respective gas ejection holes 8, that is, coincide with the respective gas ejection holes 8 in the circumferential direction of the gas nozzle, and are arranged in a second row in a second row so as to sandwich the fuel gas flowing out from the gas ejection holes 8. It is formed on the flame retaining plate 10.

During combustion of the gas burner 1 constructed as described above, the primary air flowing out from the primary air passage 11A is mixed with the fuel gas flowing out from the gas ejection holes 8 and then in the circumferential direction by the first flame stabilizing plate 7. Change the flow. Here, since the first flame holding plate 7 and the second flame holding plate 10 are made substantially parallel to each other, the mixed gas of the fuel gas and the primary air reaches the vicinity of the inner wall of the burner cone 5 along the second flame holding plate 10. Flowing. Then, in the vicinity of the inner wall of the burner cone 5, the mixed gas and the secondary air flowing out from the secondary air 11B hit each other at a substantially right angle and burn, and the flame is formed between the secondary air passages 11B and widely dispersed. It becomes a dispersed flame. Further, an exhaust gas recirculation region is widely formed in front of the first flame stabilizing plate 7, and the heat of the exhaust gas is supplied to the combustion region in front of the first flame stabilizing plate Q7.

When the gas burner 1 is burning as described above, the mixed gas flows along the second flame stabilizing plate 10 and the flame can be widely dispersed and spread. As a result, the effect of cooling the flame can be obtained. Can improve, suppress combustion temperature, NO
It is possible to suppress the generation of x and reduce the concentration of NOx.
Further, heat is supplied to the combustion region by the exhaust gas recirculation region formed in front of the first flame holding plate 7, and the flame holding performance can be improved.

Here, the first x when the distance x between the first flame holding plate 7 and the second flame holding plate 10 is set to K times the diameter y of the gas ejection hole 8.
The relationship with the surface temperature of the peripheral edge of the flame holding plate 7 is as shown in FIG. 3, for example. When the value of K exceeds 5, the temperature of the first flame holding plate 7 rises and the amount of NOx generated increases. Therefore, by setting the relationship between the interval x and the diameter y of the gas ejection hole 8 to be y ≦ x ≦ 5y, the generation of NOx can be suppressed low.

When the gas burner 1 burns, the amount of secondary air flowing out from the air holes 12 of the second flame holding plate 10 is the total amount of the secondary air flowing out from the secondary air passage 11B. It is about 3 to 10% of the amount of secondary air. Further, the fuel gas flowing out from the gas ejection holes 8 and the primary air flowing out from the primary air passage 11A are mixed, and the mixed gas flows in the circumferential direction. At this time, the secondary air flowing out from the air holes 12 flows almost at right angles to the flow of the mixed gas, and is split into each of the gas ejection holes 8. Therefore, the flow of the mixed gas flows from the air holes 12 to each other. Disturbed by the secondary air. In particular, in the low combustion region where the amount of fuel gas supplied to the gas burner is small and the flow velocity is small, the fuel gas and the air flowing out from the gas ejection holes 8 are mixed by diffusion of the gas, and the second flame stabilizing plate 10 is mixed.
The mixed gas flowing along is disturbed by the secondary air flowing out from the air holes 12 to promote mixing.

As described above, the mixed gas flowing along the flame holding plate is disturbed by the secondary air flowing out from the air holes 12 at a substantially right angle to promote mixing, so that the low flow rate of the combustion gas is particularly low in the low combustion region. The completion of combustion is promoted, the stable combustion range is expanded to the low combustion range, and the control range of the combustion amount of the gas burner can be widened.

Further, by setting the amount of the secondary air flowing out from the air holes 12 to 3% or more and 10% or less of the total amount of the secondary air, the mixing of the mixed gas can be promoted. or,
By forming the air holes 12 in the vicinity of the gas ejection holes 8, mixing can be promoted without impairing the effect of NOx reduction due to flame dispersion and division, and as a result, the control range of the combustion amount can be increased. It is possible to provide a gas burner that is wide and has excellent practicability with suppressed generation of NOx.

FIG. 4 is a characteristic diagram of the combustion range. When the air holes for mixing are not opened in the second flame stabilizing plate 10, the combustion range is as shown by the solid line in FIG. 4, and the lower limit value of the combustion amount is, for example, 2
8%. On the other hand, the air holes 12 are formed in the second flame stabilizing plate 10, and the amount of secondary air flowing out from the air holes 12 is set to, for example, 5%.
In this case, the combustion range is expanded as shown by the broken line in FIG. 4, the lower limit value of the combustion amount is, for example, 22%, and the control range of the combustion amount is 6% wider. In FIG. 4, the CO generation upper limit and the CO generation lower limit are values at which the CO generation sharply increases when the concentration in the exhaust gas increases or decreases from that value.

FIG. 5 shows a second embodiment. In FIG. 5, the same components as those in FIG. 2 are designated by the same reference numerals, and detailed description thereof will be omitted. In the gas burner shown in FIG. 5, in the second flame stabilizing plate 10, a plurality of, for example, three air pieces are provided in the vicinity of the respective gas ejection holes 8 so as to match the respective gas ejection holes 8 in the gas nozzle circumferential direction. The holes 12 are formed in a line.

During operation of the gas burner shown in FIG. 5, the second
Mixing of the mixed gas flowing along the flame stabilizing plate 10 is promoted by the secondary air flowing out from the air holes 12, and the stable combustion range can be expanded to the low combustion region. Further, since the secondary air flowing out from the air hole 12 flows out from directly below the mixed gas to the center of the mixed gas flow, that is, the place where the gas concentration is highest,
The mixing can be effectively promoted without impairing the effect of NOx reduction due to the dispersion and division of the flame.
It is suitable when the ratio of the secondary air flowing out of 2 is small, such as 4%.

FIG. 6 shows a third embodiment. In FIG. 6 as well, the same components as those in FIG. 2 are designated by the same reference numerals, and detailed description thereof will be omitted. In the gas burner shown in FIG. 6, the second flame stabilizing plate 10 is provided with a plurality of air holes 12 in the vicinity of the respective gas ejection holes 8 so as to coincide with the respective gas ejection holes 8 in the circumferential direction of the gas nozzle. It is staggered.

During operation of the gas burner shown in FIG. 6, secondary air flows out from the air holes 12 to the center and both sides of the mixed gas, and promotes mixing throughout the mixed gas without impairing the NOx reduction effect. Therefore, the stable combustion range can be further expanded. Further, in the gas burner shown in FIG. 6, the ratio of the secondary air flowing out from the air holes 12 is, for example, 8%.
Suitable for large values such as%.

[0025]

The present invention is a gas burner configured as described above, in which the first flame-holding plate and the second flame-holding plate are substantially parallel to each other, and the substantially uniform space X and the diameter Y of the gas ejection hole are set. The relation of Y ≦
Since X ≦ 5Y and the outer diameter of the first flame holding plate was made smaller than the inner diameter of the second flame holding plate, the mixed gas flows in the circumferential direction of the gas nozzle along the second flame holding plate, and the flame is widely dispersed. As a result, the cooling effect of the fire is improved, the combustion temperature can be suppressed, and the production of NOx can be suppressed to a low level.

Since a plurality of air holes are formed in the second flame holding plate near the gas ejection holes formed in the gas nozzle, the second
The mixing of the combustion gas of the mixed gas flowing along the flame stabilizing plate with the secondary air can be promoted by the secondary air flowing out from the air holes without impairing the NOx reduction effect by the dispersion and division of the flame. The low combustion range can be expanded, and as a result, the stable combustion range can be expanded.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a gas burner of the present invention.

FIG. 2 is a front view of the gas burner of the present invention.

FIG. 3 is a characteristic diagram of a surface temperature of a second flame stabilizing plate.

FIG. 4 is a combustion range diagram of the gas burner.

FIG. 5 is a front view of a gas burner showing a second embodiment.

FIG. 6 is a front view of a gas burner showing a third embodiment.

[Explanation of symbols]

 1 Gas Burner 3 Blower 4 Gas Nozzle 5 Burner Cone 7 First Flame Retaining Plate 8 Gas Injection Hole 10 Second Flame Retaining Plate 11A Primary Air Passage 11B Secondary Air Passage x Distance between First Flame Retaining Plate and Second Flame Retaining Plate y Diameter of gas ejection hole 12 Air hole

Claims (2)

(57) [Claims] 1. A first flame holding plate is connected to a tip of the first flame holding plate.
Combustion formed between a gas nozzle having a plurality of gas ejection holes formed in the peripheral wall near the flame holding plate, a plurality of secondary air passages for combustion formed by dividing the periphery and the outer periphery of the gas nozzle provided in the center In a gas burner including a second flame holding plate having a primary air passage for use, and a burner cone having the second flame holding plate connected to an inner wall, a first flame holding plate and a second flame holding plate are provided.
When the substantially uniform spacing between the two flame holding plates is set to be X and the diameter of the gas ejection holes is Y, Y ≦ X ≦ 5Y is satisfied and the first flame holding plate is provided. A gas burner characterized in that the outer diameter of the plate is made larger than the inner diameter of the second flame holding plate. 2. A first flame holding plate is connected to the tip, and the first flame holding plate is connected to the first flame holding plate.
Formed between the gas nozzle having a plurality of gas ejection holes formed in the peripheral wall near the flame holding plate of No. 3, a plurality of secondary air passages for combustion formed by dividing the peripheral edge of the gas nozzle, and the outer periphery of the gas nozzle provided in the center. In the gas burner including the second flame holding plate having the primary combustion air passage for combustion, and the burner cone connecting the second flame holding plate to the inner wall, the second flame holding plate is the first flame holding plate. A gas burner characterized in that a plurality of air holes are provided substantially parallel to the flame stabilizing plate and near the gas ejection holes.