JPH0126444B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion air supply system, and particularly to a combustion air supply system for reducing nitrogen oxides (NOx) in a combustion device such as a boiler system.
The present invention relates to a combustion air supply device having an exhaust gas mixing means as a measure to reduce the amount of gas.

Conventionally, NOx in combustion equipment such as boilers
As reduction methods, a method of mixing boiler exhaust gas with combustion air and a method of performing two-stage combustion to slow the combustion speed have been implemented. Each of these methods has a NOx reduction effect when used alone, but
If both methods are used in combination, an even better synergistic effect can be obtained.

In other words, Figure 1 shows the changes in the amount of NOx generated and the amount of dust at the boiler outlet when combustion air is mixed with boiler exhaust gas. The amount of NOx generated is lower in case (B), which combines combustion with two-stage combustion. Regarding the amount of dust, the case where exhaust gas mixing and two-stage combustion are combined (however, only air is supplied from the over air port) is lower than the case where only exhaust gas mixing is used (C).
(E) has a smaller amount of dust particles. On the other hand, when exhaust gas is mixed with the air supplied from the over-air port for two-stage combustion (D), there is a tendency for the amount of dust to increase as the amount of mixed exhaust gas increases compared to when only air is used (E). It will be done. Note that the reason why the amount of dust particles decreases as the amount of mixed exhaust gas increases is considered to be because the amount of gas increases and the diffusion of unburned matter is improved. As a specific means of mixing the exhaust gas, the second
As shown in the figure, when air is supplied from the forced draft fan 1 to the burner section 3 and over-air port 4 of the furnace 5 through the primary air passage 2, gas is recirculated only to the secondary air passage 2A of the burner section 3. The exhaust gas from the fan 6 is supplied and mixed, or as shown in FIG.
A method has been adopted in which exhaust gas is supplied and mixed from a gas recirculation fan 6 to the primary air passage 2, and a common mixed air is supplied to the burner section 3 and the over air port 4.

However, in the above-mentioned conventional technology, exhaust gas is supplied only to the burner section, or exhaust gas of the same mixed composition is supplied to the burner section and the over-air port. It has been difficult to control the amount of exhaust gas supplied to the burner section and the over-air port section at an arbitrary ratio depending on the difference in the amount of NOx generation and the amount of dust particles.

SUMMARY OF THE INVENTION An object of the present invention is to provide a combustion air supply device that eliminates the drawbacks of the prior art described above and can change the amount of exhaust gas mixed into the burner section and the over-air port section at an arbitrary ratio.

In order to achieve the above purpose, we have created a combustion air supply path separated by a partition plate that communicates with the burner section and over-air port section of the furnace, and an exhaust gas blowout path that mixes exhaust gas into the combustion air supply path. an exhaust gas distribution pipe having an opening, the exhaust gas distribution pipe having a wedge-shaped outer shape with an exhaust gas inlet at the end and a plurality of exhaust gas outlets at the side; It is characterized in that the wedge-shaped head is disposed so as to straddle the combustion air supply path to the burner section and the over-air port section, and so that the wedge-shaped head faces the combustion air flow.

In the air supply device of the present invention, it is preferable that the exhaust gas distribution pipe is vertically arranged in a duct divided into upper and lower parts by a partition plate.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 4 is a diagram showing an air supply system of a boiler device showing one embodiment of the present invention. This equipment system includes an exhaust gas mixing device 8 to which air is supplied by a forced air blower 1 through a primary air duct 2, and an exhaust gas mixing device 8 to which in-furnace combustion exhaust gas is supplied from a gas recirculation fan 6 through a flue 7; The system includes a system for supplying gas mixed at a desired ratio in a mixing device 8 to the burner section 3 and over air port 4 of the furnace 5 via secondary air passages 2A and 2B, respectively. The air exiting the forced air blower 1 enters the exhaust gas mixing device 8 via the air duct 2, where it is divided into two parts and mixed with a desired amount of combustion exhaust gas, and then transferred to the branch air duct 2A,
2B, it is distributed to the burner 3 and over-air port 4, enters the furnace 5, and is used as combustion air. Note that the combustion exhaust gas is pressurized by the gas recirculation fan 6, passes through the flue 7, enters the exhaust gas mixing device 8, and is mixed with the air supplied from the forced draft fan 1 as described above.

The exhaust gas mixing device 8 includes a wind duct divided into two by a partition plate (secondary air duct), an exhaust gas distribution pipe having an opening for blowing out the exhaust gas supplied from the exhaust gas flue into the wind duct, and the opening. damper means that can arbitrarily change the opening area of the section. Fifth
The figure is a configuration diagram showing an example of the exhaust gas mixing device,
and FIG. 6 are diagrams showing details of the mixing section. In the figure, a main airway (primary airway) 2 is divided by a partition plate 10 into airways (secondary airway) 2A and 2B.
The secondary air ducts 2A and 2B are vertically provided with an exhaust gas distribution pipe 11, and the upper and lower openings 9B and 9A are branch flues 12B and 12 branched from the main exhaust gas flue 12, respectively. 12A
It is open to As shown in FIG. 6, the exhaust gas distribution pipe 11 has a wedge-shaped outer shape with upper and lower exhaust gas inlets 9B and 9A, and a plurality of exhaust gas outlets 13 are provided in the vertical direction on the side thereof, and Each spout 13 is provided with a damper 14, so that its opening area can be adjusted. The damper 14 is preferably of a rotary vane type as shown in the figure, but may be of other shapes as long as the opening area can be changed arbitrarily.

In the above configuration, combustion air is passed through the secondary air passages 2A and 2B, and is supplied to the over air port 4 and the burner section 3, respectively, as shown in FIG. 4. However, when mixing combustion exhaust gas, The degree of opening of the damper 14 at the opening of the exhaust gas distribution pipe 11 provided in the secondary air ducts 2A and 2B may be adjusted, and a desired amount of exhaust gas may be supplied and mixed from the opening to the air ducts 2A and 2B. .

In the above embodiment, the damper 14 of the exhaust gas distribution pipe 11 can be adjusted independently. The dampers 14 may be connected by a link mechanism. In addition, by connecting the above-mentioned vertically divided parts with a link mechanism so that their operations are reversed, the burner part (in this case, the lower exhaust gas outlet) and the over air port part (in this case, the upper exhaust gas outlet) are connected. ) can be adjusted with good responsiveness.

As described above, according to the present invention, by arbitrarily adjusting the amount of combustion exhaust gas supplied and mixed to the burner section and the over-air port, it is possible to solve the conventional drawbacks associated with exhaust gas mixing and two-stage combustion (for example, to reduce NOx). , the amount of pollutants increases, and conversely, if you try to reduce the amount of pollutants, NOx increases). It can be used effectively.

[Brief explanation of drawings]

Figure 1 is a diagram showing the NOx and dust generation characteristics when using the two-stage combustion method and exhaust gas mixing method to explain the points of view of the present invention, and Figures 2 and 3 are diagrams showing the conventional exhaust gas mixing method. Fig. 4 is a system diagram of an apparatus for an exhaust gas mixing method showing an embodiment of the present invention, and Fig. 5 is a detailed diagram of an exhaust gas mixing section of an air supply device showing an embodiment of the present invention. , FIG. 6 is an enlarged view of the exhaust gas distribution pipe of the apparatus shown in FIG. 5. 2...Primary wind duct, 2A, 2B...Secondary wind duct, 3
...Burner part, 4...Over airport, 5...
...Furnace, 8...Exhaust gas mixing device, 9A, 9B...
Exhaust gas inlet, 10... Partition plate, 11... Exhaust gas distribution pipe, 12... Main flue, 12A, 12B... Branch flue.

Claims (1)

[Scope of Claims] 1. A combustion air supply path separated by a partition plate, which communicates with the burner section and over-air port section of the furnace, and an exhaust gas blowing path for mixing exhaust gas into each of the combustion air supply paths. an exhaust gas distribution pipe having an opening, the exhaust gas distribution pipe having a wedge-shaped outer shape with an exhaust gas inlet at the end and a plurality of exhaust gas outlets at the side; A combustion air supply characterized in that the wedge-shaped head is disposed so as to straddle the combustion air supply path to the burner section and the over-air port section, and such that the wedge-shaped head faces the combustion air flow. Device. 2. The combustion air supply device according to claim 1, wherein the exhaust gas outlet is provided with a flow rate regulating means.