JPH09145024A - Square shaped nozzle mixing burner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a square shaped nozzle mixing burner having high performance at low cost. SOLUTION: A flat square burner head 2 is disposed near an opening surface of a long box-shaped easing 1 at the center in the width direction thereof, and spaces between both sides of the head 2 and the inside surfaces of the casing 1 are closed with rectangular baffle plates 3, respectively, and notches 4 are provided on the outer side edge of each plate 3 at predetermined intervals to form combustion air blowoff holes 4, and a gas blowoff hole 5 is provided on both side surfaces or only on one side surface of the head 2 at the center between adjacent notches 4 downstream of the plate 3. As a result, spaces can be effectively utilized according to a square type furnace body and thickness of flame can be reduced and divided flame can be provided to reduce amounts of NOx generation, and manufacturing can be achieved at low cost by merely welding or assembling using plates, square materials, round bars and further stable combustion at high load can be realized by forming eddy current. In asymmetrical gas blowoff holes, NOx can be further reduced by air two-stage combustion and recycling of exhaust gas in furnace can be accelerated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a premixed gas burner used in boilers, industrial furnaces and the like.

[0002]

2. Description of the Related Art Conventionally, many boilers and industrial furnaces are manufactured in a round shape as shown in FIG. 7 (a) in view of production cost and strength, and the burner 11 attached to them is also a round shape. In recent years, due to the demand for space saving and high efficiency, the number of rectangular furnace bodies 10 is increasing. However, the premixed burners attached to these are still mainly round type. The pre-mixing method is more widely used in this type of burner since it has less risk of backfire than the original mixing method and has a large ratio (turndown) between the maximum combustion amount and the minimum combustion amount. .

[0003]

When the furnace body 10 has a square shape, it is more rational to make the burner 11 also a square shape as shown in FIG. 7 (b), which is suitable for a space saving request. However, since the square type has a higher manufacturing cost and a more complicated structure than the round type, there has been no premixed type high load square burner in the past. In view of such problems, the present invention can be manufactured with only a cheap material having a simple structure, and is space-saving and low NOx.
It is an object of the present invention to provide a pre-mixing type burner that can realize the above, and that can perform stable combustion and complete combustion.

[0004]

As shown in FIGS. 1 to 3, a rectangular premix burner according to the present invention is a rectangular tube having a flat shape at the center in the width direction near the opening surface of a long box-shaped casing 1. -Shaped burner heads 2 are arranged, and the intervals between the both side surfaces of the burner head 2 and the inner side surface of the casing 1 are closed by rectangular baffle plates 3, respectively, and provided on the outer edges of both baffle plates 3 at regular intervals. Combustion air ejection holes 4 are formed by the notches 4, and the downstream side of the baffle plate 3 and the adjacent 2
The gas ejection holes 5 are provided on the both side surfaces of the burner head 2 or on only one side surface thereof at the center of each of the notches 4.

[0005]

1 and 2 (a) show an embodiment of the present invention, in which a rectangular cylindrical burner having a flat box-shaped casing 1 having an open upper surface in the center in the width direction is shown. The width of the rectangular baffle plate 3 provided with the head 2 and projecting from both side surfaces of the burner head 2 is exactly the same.
Is formed in such a size that it closes the gap between the outer surface of the baffle plate 3 and the inner surface of the casing 1, and the combustion air ejection holes 4 are formed by the rectangular notches 4 provided at the outer edges of the baffle plates 3 at regular intervals. Has been done. Combustion air supplied from the air supply pipe connection port 6 to the lower part of the casing 1 is sent to the lower side of the baffle plate 3 via an air dispersion plate 7 made of a perforated plate (so-called punching metal), and the air distribution plate 7 Is ejected from each notch 4 with a uniform pressure. On both side wall surfaces of the burner head 2 above the baffle plate 3, gas ejection holes 5 are formed at positions corresponding to the centers of two adjacent notches 4.
Is provided, and the fuel gas ejected laterally from the ejection hole 5 and the combustion air ejected upward from below are mixed to form a flame A above the fuel gas. Casing 1
The opening surface of the burner head 2 is partially shielded by the flame holding plate 8 fixed to the upper surface of the burner head 2, and therefore the wall surface of the burner head 2, the inner wall surface of the casing 1, the baffle plate 3 and the flame holding plate 8 are formed. A vortex flow as shown by an arrow a is formed in the enclosed mixing chamber 9, and the vortex flow sufficiently mixes the fuel gas and the combustion air to perform combustion with a high load factor.

FIG. 4 shows the positions of the gas ejection holes, flame length and NO.
It is a graph showing the relationship with the x generation amount. As shown in the figure, when the gas ejection holes are located in the center between the cutouts of the baffle plate, they show the maximum flame length and the lowest NOx value. Therefore, in order to shorten the flame, this position can be shifted to the left or right. The NOx generation amount at the central position of the burner (symmetrical type) of the present invention is 100
%, The NOx generation amount of the conventional type normal gas burner is about 200 to 250. As shown in FIG. 5, the NOx value could be reduced in this way because the flame thickness could be made thinner than that of the round burner, and the split flame was formed by the baffle plate, so that the fuel was This is probably because the time of exposure to high temperature could be shortened.

FIG. 2 (b) shows another embodiment of the present invention, in which the gas ejection holes 5 of the burner head 2 are provided only on one side wall surface thereof, so that the flame B has a different shape. It is asymmetric. The other structure is exactly the same as that of the above embodiment. In such an asymmetric type, since the entire amount of fuel gas is ejected from the gas ejection holes 5 on only one surface of the burner head 2, the primary flame is formed in a state where the fuel gas is excessive with respect to the air supply amount, Next, the combustion air ejected from the opposite side of the burner head 2 comes into contact with the primary flame and reacts with the unburned gas in the flame to completely burn it. That is, by performing the two-stage air combustion, the combustion can be slowed and the NOx generation amount can be reduced by 20 to 30% as compared with the symmetrical type. At this time, flame B is shown in FIG.
As shown in (b), the gas is inclined toward the gas ejection hole 5 side. This characteristic is shown in FIG.
Very advantageous when heating the. That is, in the figure, a flame B with a relatively thin thickness due to a square burner is used.
Flows toward the inner side of the furnace where the flow is apt to stagnant, so that the inside of the furnace is heated uniformly and the combustion exhaust gas flows back to the burner side through the center of the furnace as shown by arrow b. ,
With so-called two-stage air combustion, so-called exhaust gas recirculation is effectively performed in which the exhaust gas is entrained in the flame to suppress NOx generation by slow combustion.

[0008]

EXAMPLE The dimensions of each part of the burner of the present invention having a combustion amount of 150,000 kcal / h are as follows. Length of one side of notch (square): 5 to 15 mm Width of flame holding plate: 10 to 60 mm Diameter of gas ejection hole: 2 to 5 mm Pitch of gas ejection hole (notch): 20 to 40 mm Number of gas ejection holes: 8 to 10 pieces Number of cutouts: 9 to 11 pieces Distance between gas ejection hole and baffle plate: 5 to 20 mm Width of burner head: 15 to 50 mm Length of burner head (casing): 350 to 450 mm Width of casing: 80 -150 mm Casing height: 300-500 mm Flame length (air ratio = 1.1): 150-300 mm In order to increase the combustion amount by n times, the burner head length is set to n.
You can double it.

[0009]

As described above, according to the present invention, since the premixing burner is formed in the square shape, the space can be effectively utilized by adapting to the square type furnace body and the flame can be used. NO because it can be made thinner and divided flame
x has the advantage of being able to reduce the amount of generation, and at the same time, can be manufactured inexpensively by welding and screwing only using plate materials, square bars and round bars. Moreover, by appropriately setting the width of the flame holding plate, a vortex flow can be formed. There is an advantage that stable, complete and high-load combustion can be realized. Furthermore, if a gas injection hole is provided on only one side to make it an asymmetric type, NO is generated by two-stage air combustion.
There is an advantage that the x reduction rate can be further improved and the exhaust gas recirculation in the furnace can be promoted.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, in which (a) is a top view and (b) is a vertical sectional view.

FIG. 2 is a transverse sectional view of the same.

FIG. 3 is a perspective view of a main part of the above.

FIG. 4 is a graph showing flame length and low NOx characteristics of the same.

FIG. 5 is a schematic diagram showing the shape of a flame of the same.

FIG. 6 is a plan sectional view showing a state in which the same is mounted on a furnace body.

FIG. 7 is an explanatory view showing a problem of the conventional round burner.

[Explanation of symbols]

 1 casing 2 burner head 3 baffle plate 4 notch 5 gas ejection hole 6 air supply pipe connection port 7 air dispersion plate 8 flame holding plate 9 gas supply pipe 10 burner 11 furnace body 12 chimney 13 water pipe

Claims (3)

[Claims] 1. A flat rectangular burner head is arranged in the width center near the opening surface of a long box-shaped casing, and a rectangular baffle plate is provided between each side surface of the burner head and the inner surface of the casing. Combustion air ejection holes are formed by notches provided at the outer edges of both baffle plates at regular intervals, and both side surfaces of the burner head are located downstream of the baffle plates and in the center of the two adjacent notches. Square type premix burner with gas injection holes in the. 2. A flat rectangular burner head is arranged in the width center near the opening surface of a long box-shaped casing, and the space between each side surface of the burner head and the inner surface of the casing is formed by a rectangular baffle plate. Combustion air ejection holes are formed by notches provided at the outer edges of both baffle plates at regular intervals, and one side surface of the burner head is located downstream of the baffle plates and at the center of the two adjacent notches. Square type premix burner with gas injection holes in the. 3. The square premix burner according to claim 1, wherein a flame holding plate having a width wider than that of the burner head is provided on the opening surface of the casing so as to cover the burner head.