JPS596326B2 - Low NO↓x device - Google Patents

Description

[Detailed description of the invention] This invention relates to combustion.

Currently, in order to prevent pollution, NO contained in combustion exhaust gas is
It is desired to reduce x.

Conventionally, methods for reducing NOx contained in exhaust gas from gas burners include a two-stage combustion method, a concentration combustion method, and the like.

The two-stage combustion method is a method of supplying combustion air in two stages.The first stage supplies approximately 80% of the theoretical amount of combustion air at the burner combustion port, and the second stage supplies combustion air at a rate of approximately 80% of the theoretical air amount at the burner combustion port. Approximately 2 of the air volume
Provide 5-30% combustion air.

However, in this method, it is necessary to provide a secondary combustion air supply port in the downstream part of the furnace, that is, in the furnace wall.
Water tube boilers have the problem of requiring machining of the furnace wall water tube group, and furnace wall boilers require machining of the furnace wall.

In addition, in the concentrated combustion method, some of the burners are made to have an excess of fuel, and the surrounding burners are made to have an excess of air, or only combustion air is sent to the surrounding burners. It's a method.

However, this method has a problem in that it is applicable only to devices having a large number of burners.

This invention was made to solve the above-mentioned problems.
Another object of the present invention is to provide a premix burner device that can reliably reduce NOx by performing two-stage and concentrated combustion without requiring a large number of burners.

In order to achieve this object, in the present invention, in the annular premixed burner, the fuel injection hole is formed into a conical ring shape that spreads inside the furnace, and air is partially injected just before the excess premixed fuel is ejected. Supply premixed fuel.

FIG. 1 is a sectional view showing a gas burner according to an embodiment of the present invention when gas is used as fuel, and FIG.
It is an A sectional view.

In the figure, 1 is a furnace wall, 2 is an annular premixed gas fuel injection hole provided in the furnace wall 1, and the injection hole 2 is in the shape of a conical ring extending inside the furnace.

Reference numeral 3 denotes a partition plate installed inside the ejection hole 2, and the partition plate 3 partitions the ejection hole 2.

4 is a secondary air chamber provided inside the nozzle 2; 5 is a secondary air nozzle provided on the inner wall of the nozzle 2;
is provided near the outlet of the jet hole 2.

6 is a premixing chamber connected to the nozzle 2, 1 is a fuel nozzle 8
a fuel manifold connected to a premixed metal coating 6 via a fuel manifold, 9;
1 is a wind box connected to the premixing chamber 6, and 10 is a combustion air adjustment damper provided in the wind box 9. The damper 10 is automatically controlled according to the amount of fuel supplied.

11 is a secondary air pipe whose one end is connected to the wind box 9 and the other end is connected to the secondary air chamber 4; and 12 is a secondary air damper provided in the secondary air pipe 11.

With this structure, fuel gas is supplied into the manifold 1, the fuel gas is introduced into the premixing chamber 6 through the jet nozzle 8, and combustion air is supplied into the wind box 9, so that the damper By adjusting 12, the theoretical air amount is approximately 8
If 0% combustion air is introduced into the premixing chamber 6 and about 25 to 30% of the theoretical air amount is introduced into the secondary air chamber 4 through the secondary air pipe 11, primary air and gas fuel can be combined. is mixed in the premixing chamber 6 and ejected from the ejection hole 2, while secondary air is ejected into the ejection hole 2 through the ejection hole 5, and premixed gas fuel with excess fuel is ejected from the ejection hole 2. Immediately before, secondary air is partially supplied.

Therefore, the premixed gas fuel with excess air is ejected from the ejection holes 2a having the ejection holes 5, and the premixed gas fuel containing excess fuel is ejected from the ejection holes 2b without the ejection holes 5.

For this reason, the oxygen concentration in the combustion zone is low, the combustion temperature is low, and since the nozzle 2 has a conical ring shape that extends inside the furnace, the pressure inside the flame is low and the self-recirculation flow is increased. As combustion gas with low temperature and low oxygen partial pressure flows into the flame, the combustion temperature becomes low and
Since the combustion gas flows backward toward the furnace wall 1 due to the self-recirculating flow, the flame approaches the furnace wall 1.

Furthermore, since the secondary air is supplied immediately before the premixed gas fuel is ejected from the ejection hole 2, an excess air region and an excess fuel region are clearly formed, so that concentrated combustion can be reliably performed.

In addition, secondary air is partially supplied to the premixed gas fuel ejected from the nozzle 2, so that the concentration of the premixed gas fuel is continuous and there is a region with an appropriate amount of air, so combustion is stable. do.

Furthermore, it is possible to perform concentrated and light combustion with a single burner,
In addition, since the structure is simple, the low NOx burner device of the present invention can be manufactured by easily modifying a conventional burner.

As explained above, in the gas burner according to the present invention, two-stage combustion and concentrated combustion can be performed by itself.

That is, in this burner, two-stage combustion can be performed without providing a second-stage combustion air supply port in the furnace wall, and concentrated combustion can be performed without requiring a large number of burners.

In addition, combustion gas having a low temperature and a low oxygen partial pressure flows into the flame due to the self-recirculating flow, so that concentrated combustion can be performed more reliably.

Therefore, the combustion temperature is lowered, and it is possible to reliably reduce the amount of NOx generated.

Furthermore, combustion is stable, and a conventional burner can be easily modified to manufacture the low NOx burner device of the present invention.

As described above, the effects of this invention are remarkable.

Although the partition plate 3 is provided in the above-mentioned embodiment, it is possible to form a rich fuel region and a fuel lean region without providing the partition plate 3.

However, it is more effective if the partition plate 3 is provided.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a gas burner according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line AA in FIG. 1... Furnace wall, 2... Premixed gas fuel injection hole, 3...
・Partition plate, 4...Secondary air chamber, 5...Secondary air outlet, 6...Premixing chamber, 7...Fuel manifold, 9
...Wind box, 10...Combustion air adjustment damper, 11.
...Secondary air pipe, 12...Secondary air damper.

Claims (1)

[Claims] 1. A premixed burner characterized in that the fuel injection hole is formed into a conical annular shape extending inside the furnace, and air is partially supplied to the premixed fuel with excess fuel immediately before the premixed fuel is ejected. NOx burner device.