JP2928152B2 - Low NOx boiler with water tube group and burner in close proximity - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiler in which a group of water tubes and a burner are provided close to each other, and a flame from the burner is brought into contact with the water tubes to lower the flame temperature and reduce the amount of NOx generated.

[0002]

2. Description of the Related Art In recent years, it has become particularly important to reduce the amount of NOx which is a harmful substance. Since NOx is generated frequently when the flame is at a high temperature, the temperature of the flame generated from the burner is reduced at an early stage to reduce NOx. When the water pipe group and the burner are brought close to each other and the flame from the burner intersects with the water pipe group, the flame can be cooled by the water pipe. In this case, the flame temperature can be lowered at an earlier stage as the water tube group and the burner are closer, but if the water tube group and the burner are too close, the spark rod goes to the water tube when generating a spark to ignite the burner. There is a problem that sparks occur. For this reason, it is necessary to keep a certain distance (for example, 30 mm) or more between the water pipe group and the burner, and the decrease in flame temperature is delayed by that much, and a lot of NOx is generated before the flame reaches the water pipe. Therefore, it was not possible to sufficiently reduce NOx.

[0003]

An object of the present invention is to provide a boiler which generates a flame in a direction crossing a group of water tubes, while preventing a spark from being emitted toward the water tubes at the time of ignition. It is to reduce NOx by bringing the water tube group and the burner closer.

[0004]

An upper header and an lower header are arranged at an upper part and a lower header at a lower part, and the upper and lower headers are connected by a number of vertical water pipes arranged in a staggered manner. In a boiler configured to provide a burner that generates a flame toward the water pipe group on the side of the water pipe group, and to intersect the flame generated by the burner with the water pipe, a spark rod that generates a spark toward the combustion part of the burner is provided. Set it up,
Of the first row of water pipes facing the burners in the water pipe group, the gap between the water pipes is widened by increasing the gap between the water pipes at the portion closest to the spark rod, and sparks are generated from the spark rods to the water pipes. Bring water tubes and burners close together so that they are not emitted.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. The upper header 1 and the lower header 2 are connected by a number of vertical water pipes 3, the periphery of the water pipe group is surrounded by a furnace wall 10, a burner 4 is provided on one side of the furnace wall 10, and a burner 4 is provided on the other side. A flue gas outlet 5 is provided. Water pipe 3 goes to burner 4
The rows are arranged in a staggered manner in rows of rows, and the rows closer to the burner 4 are referred to as first to fourth rows. The burner 4 is provided with a mixing chamber 7 for mixing the combustion air and the fuel gas in front of the combustion surface 6, and penetrates the mixing chamber 7 and the combustion surface 6,
A spark rod 8 and a frame rod 9 whose tips reach the surface of the combustion surface 6 are provided, and the spark rod 8 and the frame rod 9 are arranged so as to be vertically aligned at the periphery of the combustion surface 6. The first row of water tubes consists of three water tubes 3, but the spacing between the water tubes in the first row is different,
The space on the side where the spark rod 8 and the frame rod 9 are provided is widened. By increasing the distance between the water pipes, the distance from the spark rod 8 to the water pipes is increased, so that no spark is emitted toward the water pipes.
And the first row of water tubes 3 can be closer than 30 mm. Of the second row of water pipes, the water pipe downstream of the widened gap in the first row is brought closer to the first row so that the gap between the first row and the second row of water pipes is not excessively opened. Furnace wall 1
A flue 11 for discharging flue gas is connected to the flue gas outlet 5 provided at 0, and a gap between two water pipes close to the flue gas outlet 5 among the water pipes in the second and third rows is closed. In addition, the combustion gas is prevented from being short-passed and exhausted.

The steam is generated by supplying water to the water pipe 3 through the lower header 2 and burning the burner 4. When the fuel gas and the combustion air are introduced into the mixing chamber 7 of the burner 4, mixing is performed in the mixing chamber 7 to become a premixed gas, and the premixed gas is injected from the combustion surface 6 toward the water pipe group. . When a voltage is applied to the spark rod 8, a spark is emitted from the spark rod 8 toward the combustion surface 6, and the premixed gas injected from the combustion surface 6 is ignited to generate a flame, which generates a flame burning toward the water pipe. I do. At this time,
Since the space between the spark rod 8 and the water pipe 3 is sufficiently open, no spark is emitted from the spark rod 8 toward the water pipe 3. The presence / absence of a flame is detected by the frame rod 9 provided in the same gap as the gap between the water tubes widened for the spark rod 8. The flame from the combustion surface 6 intersects with the water pipe 3, and the water in the water pipe is heated by contact with the water pipe 3, and the temperature of the flame is reduced instead. Since the water pipe 3 and the burner 4 can be sufficiently close to each other, the time when the flame is at a high temperature is extremely short, and the generation amount of NOx can be kept at a low level. In the portion where the gap between the water pipes in the first row is widened, the water pipes in the second row are close to the first row, so that the space between the water pipes in the first row and the water pipe in the second row does not become too wide. Since the flame does not reach the inside of the water tube group without contacting the water tubes, the time during which the flame temperature is in the high temperature region where the amount of NOx generated is large is shortened. The flame becomes a high-temperature combustion gas in the middle of the water pipe group, and heats the water in the water pipe 3 and the water in the water pipe while flowing crossing the water pipe. Road 11
Sent to and exhausted. The water in the water pipe 3 is heated to generate steam, and the steam is taken out from a steam take-out pipe 12 connected to the upper header 1.

[0007] As a method of adjusting the spark rod 8 to the gap between the water pipes, the installation position of the burner 4 may be shifted, which may reduce the change of the water pipe position in some cases.

[0008]

By practicing the present invention, it is possible to bring a group of water tubes and a burner close while preventing sparks from being emitted toward the water tubes at the time of ignition, so that the flame is cooled in a short time and NOx is generated. The quantity can be kept at a low level.

[Brief description of the drawings]

FIG. 1 is an AA cross-sectional view of an embodiment of the present invention.

FIG. 2 is a vertical sectional view taken along line BB of one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper header 2 Lower header 3 Water pipe 4 Burner 5 Combustion exhaust gas outlet 6 Combustion surface 7 Mixing chamber 8 Spark rod 9 Flame rod 10 Furnace wall 11 Flue 12 Vapor extraction pipe

Claims (3)

(57) [Claims] An upper header is disposed at an upper part, and a lower header is disposed at a lower part. The upper and lower headers are connected by a large number of vertical water pipes arranged in a staggered manner. A burner that generates a flame toward the water tube group is provided on the side portion, and in a boiler configured to cross the flame generated by the burner and the water tube, a spark rod that generates a spark toward the combustion portion of the burner is provided. Of the first row of water pipes facing the burners in the water pipe group, the gap between the water pipes is widened by increasing the gap between the water pipes at the portion closest to the spark rod, and sparks are generated from the spark rods to the water pipes. A low NOx boiler in which a water tube group and a burner are close to each other, wherein the water tube group and the burner are close to each other so as not to be emitted. 2. The low NOx boiler according to claim 1, wherein a flame rod for detecting a flame of the burner is provided so as to be arranged vertically with the spark rod, and the spark rod and the flame rod are connected to the water pipe. A low NOx boiler in which a water pipe group and a burner are brought close to each other, wherein the boilers are provided in a portion where a gap between them is widened. 3. The combustion gas flow in the low NOx boiler according to claim 1, wherein the space between the first row of water pipes is widened in the second row of water pipes from the burner. Low NOx in which a water pipe group and a burner are brought close to each other, wherein a water pipe located downstream is brought closer to the first water pipe row.
boiler.