JPH11294721A - Combustion burner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce NOx by burning the fuel gas of low pressure without pre- mixing with air to suppress the supply pressure of fuel gas, for 2-stage combustion. SOLUTION: Related to a combustion burner 1 wherein a fuel gas 10 of low pressure is burned without pre-mixing with air, the combustion burner 1 comprises a bottomed cylinder 2 wherein a disk-like bottom plate 3 is provided at one end while the other end is opened. A whirling combustion part 8a on the bottom plate 3 side and a secondary combustion part 8b on opening side are provided inside, a fuel supply pipe 5 is connected to the bottom plate 3, and an air supply pipe 6 is connected to a wall surface of the whirling combustion part 8a in tangent direction while a secondary air supply pipe 7 is connected to the wall surface of the secondary combustion part 8b in tangent direction, respectively, and further, a fuel jetting plate 4 comprising a multiple of fuel jetting holes 4a is provided to form a combustion chamber 9 near the bottom plate 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion burner used for a small boiler or the like, and more particularly to a combustion burner using low pressure fuel gas as fuel.

[0002]

2. Description of the Related Art In recent years, small boilers have become widespread in various fields, such as being easy to handle and space saving. ing.

[0003] The downsizing of the boiler is accompanied by a reduction in the volume of the combustion chamber, and an increase in the volume load promotes an increase in the emission of NOx. Therefore, the conventional combustion burner has a limit in reducing the NOx.

[0004] Against this background, premixed combustion burners have been used to significantly suppress the generation of NOx.

FIG. 3 is a schematic diagram of a compact boiler having a premixed combustion burner. In the figure, reference numeral a denotes a boiler, which is configured by arranging a wind box b, metal fibers, a front row water pipe group, a heat insulating space, and a rear row water pipe group in series. c is an air supply pipe, and d is a fuel gas supply pipe.

[0006] After the fuel gas is premixed with air in the wind box b, it passes through the metal fiber, starts burning near its surface, and completes combustion through the front row water pipe group and the adiabatic space. . Thus, in the boiler a, the generation of NOx is suppressed by the combination of the metal fiber and the front row water pipe group and the rear row water pipe group.

[0007]

However, in the above-mentioned boiler, since the premixed combustion is used, the fuel supply pressure must be increased, and there is a problem that the metal fibers are liable to be clogged with dust and the like and are difficult to handle. Also, in some regions such as local cities, the pressure of fuel gas is low,
In some cases, such a burner cannot be used.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and the fuel gas is burned without being premixed with air, so that the fuel gas supply pressure can be suppressed to a low level. It is an object of the present invention to provide a combustion burner in which NOx is reduced by burning.

[0009]

According to the present invention, there is provided a combustion burner for burning low-pressure fuel gas without premixing with air, the combustion burner comprising:
It has a disc-shaped bottom plate at one end and is constituted by a bottomed cylindrical body with the other end opened, and has a swirl combustion part on the bottom plate side and a secondary combustion part on the open side inside, A fuel supply pipe is connected to the bottom plate, and an air supply pipe is connected tangentially to a wall surface of the swirling combustion section, and a secondary air supply pipe is connected tangentially to a wall surface of the secondary combustion section. There is provided a combustion burner provided with a fuel injection plate having a number of fuel injection holes so as to form a fuel chamber in the vicinity.

According to a preferred embodiment of the present invention, one or more air supply pipes and two or more secondary air supply pipes are provided.

According to another preferred embodiment of the present invention,
On the wall surface of the cylindrical body, refractory bricks are arranged inside the steel plate.

According to another preferred embodiment of the present invention,
The fuel injection hole is formed in a circular shape on the outer peripheral side of the fuel injection plate by one or two.
More than columns are arranged.

Next, the operation of the present invention will be described. The combustion burner has a swirling combustion section and a secondary combustion section inside. Fuel gas is supplied to the fuel chamber from a fuel supply pipe connected to the bottom plate. After the supplied fuel gas collides with the fuel injection plate, it is dispersed along the fuel injection plate and is injected into the swirling combustion section from a plurality of fuel injection holes provided on the outer peripheral side of the fuel injection plate. On the other hand, air is supplied from an air supply pipe provided tangentially to the wall surface of the swirling combustion unit, and mixes with fuel gas in the swirling combustion unit and burns while swirling. At this time, in the swirling combustion section,
The air is made lower than the stoichiometric ratio to incompletely burn the fuel gas to lower the flame temperature. The combustion gas in the incompletely combusted state in the swirling combustion section flows down to the open secondary combustion section side while swirling from the swirling combustion section. The incompletely burned fuel gas is completely combusted on the side of the secondary combustion section by mixing with the secondary air supplied from a secondary air supply pipe provided tangentially on the wall surface of the secondary combustion section. Therefore, according to the combustion burner of the present invention, NOx can be obtained even in an area where the fuel gas pressure is low.
It is possible to perform complete combustion while suppressing the generation of water.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. 1 and 2
1 shows an embodiment of the present invention, and FIG. 1 is a plan view of a combustion burner according to the present invention. FIG. 2 is a side view of FIG. In the figure, reference numeral 1 denotes a combustion burner, which burns low-pressure fuel gas 10 without premixing with air. The combustion burner 1 includes a bottomed cylindrical body 2 having a disk-shaped bottom plate 3 at one end and an open end at the other end. Further, inside the combustion burner 1, there is formed a combustion section 8 composed of a swirl combustion section 8a on the bottom plate 3 side and a secondary combustion section 8b on the open side. The wall surface of the bottomed cylindrical body 2 is composed of an outer steel plate 2a and a refractory brick 2b disposed inside the outer steel plate 2a. Reference numeral 4 denotes a fuel injection plate provided so as to form a fuel chamber 9 near the bottom plate 3.
Two rows of fuel ejection holes 4a are provided in a circular shape on the outer peripheral side. 5
Is a fuel supply pipe connected to the center of the bottom plate 3. Reference numeral 6 denotes four air supply pipes provided tangentially to the wall surface of the swirling combustion section 8a. Reference numeral 7 denotes four secondary air supply pipes provided in the tangential direction of the wall surface of the secondary combustion part 8b.

Reference numeral 11 denotes air. 12 is secondary air.

Next, the operation of the embodiment of the present invention will be described. The combustion burner 1 has a swirling combustion section 8a and a secondary combustion section 8b inside. The fuel gas 10 is supplied to the fuel chamber 9 from a fuel supply pipe 5 connected to the bottom plate 3. After the supplied fuel gas 10 collides with the fuel injection plate 4, the fuel gas 10 is dispersed along the fuel injection plate 4 and enters the swirling combustion section 8 a from a plurality of fuel injection holes 4 a provided on the outer peripheral side of the fuel injection plate 4. Gushing. On the other hand, the air 11 is supplied from an air supply pipe 6 tangentially provided on the wall surface of the swirling combustion section 8a.
The fuel gas mixes with the fuel gas 10 and burns while turning. At this time, in the swirling combustion section 8a, the air is made lower than the stoichiometric mixture ratio, and the fuel gas 10 is incompletely burned to lower the flame temperature. The combustion gas in an incomplete combustion state in the swirling combustion section 8a flows down to the open side secondary combustion section 8b while swirling from the swirling combustion section 8a. Incompletely burned fuel gas 10 is 2
On the side of the secondary combustion section 8b, the secondary air 1 supplied from the secondary air supply pipe 7 provided tangentially to the wall surface of the secondary combustion section 8b
Completely combusts when mixed with 2. Therefore, according to the combustion burner of the present invention, it is possible to perform complete combustion while suppressing the generation of NOx even in an area where the pressure of the fuel gas is low.

The present invention is not limited to the above-described embodiment, but may be variously modified without departing from the gist of the present invention.

[0018]

As described above, according to the present invention, the fuel gas is burned without being premixed with the air, so that the fuel gas supply pressure is kept low and the fuel gas is burned in two stages. Therefore, excellent effects such as a significant reduction in NOx can be achieved.

[Brief description of the drawings]

FIG. 1 is a plan view of a combustion burner according to the present invention.

FIG. 2 is a side view of FIG.

FIG. 3 is a schematic view of a conventional compact boiler having a premixed combustion burner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Combustion burner 2 Cylindrical body 2a Steel plate 2b Refractory brick 3 Bottom plate 4 Fuel injection plate 4a Fuel injection hole 5 Fuel supply pipe 6 Air supply pipe 7 Secondary air supply pipe 8 Combustion unit 8a Swirl combustion unit 8b Secondary combustion unit 9 Fuel chamber 10 Fuel gas 11 Air 12 Secondary air

Claims (4)

[Claims] 1. A combustion burner for burning a low-pressure fuel gas without premixing with air, said combustion burner being a bottomed cylindrical body having a disc-shaped bottom plate at one end and an open end at the other end. It has a swirl combustion part on the bottom plate side and a secondary combustion part on the open side inside, a fuel supply pipe is connected to the bottom plate, and a tangential line is formed on the wall surface of the swirl combustion part. A fuel injection plate having a large number of fuel injection holes so as to form a fuel chamber near the bottom plate by connecting an air supply pipe in the direction and a secondary air supply pipe tangentially to the wall of the secondary combustion section. A combustion burner characterized by being provided. 2. The combustion burner according to claim 1, wherein one or more air supply pipes and two or more secondary air supply pipes are provided. 3. The combustion burner according to claim 1, wherein a refractory brick is provided inside the steel plate on the wall surface of the cylindrical body. 4. The combustion burner according to claim 1, wherein the fuel ejection holes are arranged in one or more rows in a circular shape on the outer peripheral side of the fuel injection plate.