JPH0116884Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a combustion air blowing device for a boiler that reduces unburned matter generated at the bottom of the boiler furnace.

One method of reducing the unburnt material generated in the reverse circulation area at the bottom (hopper section) of a conventional boiler furnace is to inject air from an air inlet 101 at the bottom of the furnace, as shown in Figure 1. A method has been proposed in which the blown air flows into the furnace 104.
Since the fuel passes through the center of the furnace, a sufficient effect is not necessarily achieved for the complete combustion of unburned matter in the reverse circulation area at the bottom of the furnace.

In addition, as shown in FIG. 1, there is an over air port (OAP) 1 on the furnace wall above the burner section 102.
A method has also been proposed in which the unburned matter is combusted with air injected from the OAP 103.
In this case as well, the unburned matter may not be completely combusted.

The present invention solves the above-mentioned drawbacks of the prior art and provides a combustion air blowing device for a boiler that makes it possible to reduce unburned matter generated at the bottom of the boiler furnace. In a combustion air blowing device for a boiler equipped with an over-air port for supplying combustion air, the furnace is penetrated into a reverse circulation area where unburned matter is retained on the bottom side of the furnace. A combustion air blowing device for a boiler, characterized in that an under-air port for supplying combustion air heat-exchanged with exhaust gas is arranged on at least one of the front wall and the rear wall of the furnace.

Therefore, the combustion air that has been heated through heat exchange with the exhaust gas passes through the reverse circulation area,
As a result, the reverse circulation region is extensively agitated, and the unburned matter retained in the reverse circulation region and fresh air are actively mixed.

Therefore, combustion in the reverse circulation region becomes better.

On the other hand, since an over-air port for supplying air for after-combustion is arranged above the burner section, an appropriate amount of fresh air is provided here as well, and unburned matter is completely combusted. Also, supplying heated combustion air through the reverse circulation zone increases the temperature of the reverse circulation zone, which itself improves combustion in the reverse circulation zone, which is detrimental to combustion.

Next, the present invention will be explained with reference to the drawings.

FIG. 2 is a system diagram of a boiler including one embodiment of the present invention.

In the figure, when bias combustion is performed as a NO _x reduction measure, unburned matter is generated in the reverse circulation area 11 at the bottom of the furnace (hopper) as described above.

In the present invention, combustion air 1 preheated by air preheater 4 with exhaust gas 9 from the boiler branches bias air 2, and the combustion air 1 after branching is the required air amount (air ratio) in burner section 3. 1a and the under air port (UAP) located on the furnace wall below the burner section 3 (both the front and rear walls in the figure).
Required air amount 1b injected from 6 into the reverse circulation area 11
It is further branched into. The amount of air 1b injected from this UAP 6 is ensured by a control damper in accordance with the load.

On the other hand, the bias air 2 is supplied to the over air port 7 (OAP) provided on the furnace wall above the burner section 3.
More injected. The port diameter of the UAP 6 is determined to maintain a penetration force suitable for the amount of injected air, and the port 6 is arranged in the furnace width direction below the burner section 3 so that the injected air penetrates and diffuses as uniformly as possible in the furnace. Place the required number of pieces.

The effects of the present invention are as follows.

(1) Complete combustion of unburned substances generated in the reverse circulation area at the bottom of the boiler furnace by injecting air.

(2) The burner section enables low air ratio combustion, which was previously impossible due to the increase in unburned content.
It is possible to have a synergistic effect of reducing NO _x and suppressing unburned substances.

(3) It has the effect of suppressing the origin of unburned matter remaining in the main combustion zone due to insufficient residence time in the over-air port and unburned matter bypassing along the furnace wall.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of an example of a conventional combustion air blowing device for a boiler furnace, and FIG. 2 is a system diagram of a boiler including an embodiment of the present invention. In the figure, 1... Combustion air, 1a... Required air amount for burner section, 1b... Air amount injected from UAP, 2... Bias air, 3... Burner section, 4
...Air preheater, 5...Boiler furnace, 6...
UAP, 7...OAP, 8...Superheater, 9...Boiler exhaust gas, 10...Boiler, 11...Reverse circulation area,
101...Air inlet at the bottom of the furnace, 102...Burner section, 103...OAP, 104...Furnace, 105
...Superheater.

Claims (1)

[Scope of utility model registration request] In a combustion air blowing device for a boiler in which an over-air port for supplying post-combustion air is arranged above the burner part of the furnace, a reverse circulation area is provided in a reverse circulation area where unburned matter is retained on the bottom side of the furnace. Combustion air for a boiler, characterized in that an under-air port for supplying combustion air that has passed through the furnace and exchanged heat with the exhaust gas of the furnace is disposed on at least one of the front wall and the rear wall of the furnace. Blowing device.