JPS6318083B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas burner for low calorie gas fuel for a corner fire ring type boiler.

When gas fuel is burned in a burner in a boiler, a diffuse combustion flame is generated in the furnace. The diffusion of air oxygen into the fuel gas is quite slow compared to oil droplet combustion, so in order to effectively mix the fuel gas and air in the furnace, various burner structures are used. Many efforts have been made to develop this method, but it is especially necessary when using low-calorie fuels such as blast furnace gas.

As shown in Figures 1a and 1b, a corner fire earring type boiler has burners 2 placed at each corner of a rectangular furnace 1, and combustion air is supplied from an air duct 3 by a ventilator to control the amount of air to each nozzle. is adjusted by opening and closing the wind box damper 4.

Figures 2a to 2e show an example of a conventional burner of this type, in which Figure 2a is a view along the Y-Y line in Figure 1b, Figure 2b is a front view of the burner, Figure 2c
2b is a view taken along the line A-A in FIG. 2b, FIG. 2d is a view taken along the line B-B in b, and e is a perspective view of b. This burner has alternately arranged fuel gas nozzles 12 and primary air nozzles 13 for combustion air.
a gas burner nozzle 11 configured as a fuel compartment containing a gas burner nozzle 11 and a secondary air nozzle 14 arranged outside and adjacent to said fuel compartment, the fuel gas being supplied from the fuel gas supply pipe 5 and the combustion The air passes through the primary air wind box damper 4 and the secondary air wind box damper 4' to the air passage 3.
is guided by Burna.

In this type of boiler, the secondary air box damper 4'
can be operated to the fully closed position, and the primary air box damper 4 can be further throttled to a certain extent, so the wind box draft can be maintained at the minimum wind pressure even under relatively low loads.

The relationship between the boiler load, the required amount of combustion air, and the burner wind box draft when the wind box damper is not operated is shown in the characteristic curves in Figure 3 a and b, respectively. The amount of combustion air decreases approximately proportionally, and the burner windbox draft decreases proportionally to the boiler load and thus to the square of the air amount. In this way, when the boiler load decreases and the burner wind box draft becomes low, an imbalance tends to occur in the amount of air distributed to each burner, causing some burners to have poor combustion. This restricts the airflow and adds resistance to the flow path to suppress imbalances in air distribution. That is, as is clear from the relationship diagram between the opening degree of the wind box damper and the damper resistance coefficient shown in Fig. 4, the resistance coefficient has sensitive positions and insensitive positions depending on the damper opening degree, and this characteristic This prevents each burner from becoming unbalanced.

Although it is advantageous to adjust the opening degree of the secondary air box damper as described above, in the high load region of the boiler, the amount of secondary air is large, and it takes time for this secondary air and fuel gas to mix. Because there is a delay and the flame becomes longer, it is necessary to design a larger furnace size.
This type of burner is uneconomical.

Furthermore, in this type of burner, when the secondary air box damper is operated in the closing direction in the low load range to increase the burner wind box resistance and suppress the imbalance in the air volume to each burner, the primary air volume is An increase in the ratio is a favorable trend for low-calorie gas fuels, but since the amount of secondary air itself is small, the nozzle speed slows down and the penetration force decreases, making it impossible to mix with the fuel gas, leaving unused air unused. As a result, the air that is discharged outside the furnace remains, making it easier for unburned gas to come out.
In order to avoid this, the excess air ratio must be increased in advance, which has the drawbacks of lowering the boiler thermal efficiency and increasing the power amount of the ventilator.

Figures 5a to 5b show other examples of conventional burners of this type, where Figure 5a is a view along the Y-Y line in Figure 1b, b is a front view of the burner, and c is a view along the line CC, and d is a view along the line D-D. This burner has fuel gas nozzles 22 arranged alternately and primary air nozzles 2 through which combustion air flows.
3, the fuel gas is guided from the fuel gas supply pipe 5, and the combustion air is guided from the air passage 3 via the primary wind box damper 4 to the burner.

In this type of burner, the primary wind box damper 4 is throttled to ensure the minimum required wind box draft, but the adjustment range is narrow due to the damper resistance characteristics, so this alone is enough to reduce the wind box draft to the required value. Since it is impossible to maintain a high excess air ratio, it is necessary to operate with a high excess air rate. Therefore, the boiler thermal efficiency decreases and the ventilation power cost increases, which is uneconomical.

The present invention aims to eliminate the above-mentioned problems of conventional burners and provide a boiler with high thermal efficiency. That is, the present invention provides a burner nozzle for a corner fire ear ring type boiler using low-calorie gas fuel, in which the imbalance in air volume of each burner is corrected by opening and closing a wind box damper. and a secondary air nozzle is arranged between the alternating fuel nozzles and the primary air nozzle within the fuel compartment; The burner nozzle is characterized by being equipped with a box damper.

Embodiments of the present invention will be described below with reference to FIGS. 6a to 6c.

Figure 6a is a front view of the burner, Figure 6b is E of a.
FIG. 6c is a view along the line F--F of a.

This type of burner is substantially the same as the burner shown in Figures 5a-d, except that it is provided with a secondary air nozzle. That is, this burner has fuel gas nozzles 32 arranged alternately, primary air nozzles 33 through which combustion air flows, and auxiliary primary air nozzles 34 for combustion air adjacent to these nozzles.
The fuel gas is supplied from the fuel gas supply pipe 5, and the fuel air is supplied from the air passage 3 to the burner via the primary air box damper 36 and the auxiliary primary air box damper 37. guided by. Such burners are placed at each corner of the boiler as shown in FIGS. 1a and 1b.

When the boiler load is high, the main primary air wind box damper 36 and the auxiliary primary air wind box damper 37 are almost fully opened, and the main primary air nozzle 33 and the auxiliary primary air nozzle 34 are fully utilized. .

When the boiler load decreases, the amount of combustion air decreases, and the air nozzle flow path resistance also decreases, which tends to cause an imbalance in the amount of air supplied to each burner. First, the auxiliary primary air box damper 37 is throttled, and if necessary, the main primary air box damper 36 is also throttled within an effective range. In this case, the auxiliary primary air nozzle 34 is the fuel air nozzle 3.
2, so no matter how the sub-primary wind box damper 37 is used to adjust the air volume and wind pressure, all of the sub-primary air is effectively mixed with the combustion gas without any waste, resulting in complete combustion. Demonstrate. Therefore, the excess air rate can be reduced, and the power cost for the ventilator is also moderate, making it possible to operate the boiler economically.

[Brief explanation of the drawing]

FIG. 1a is a side view of a corner fire ring type boiler, FIG. 1b is a plan view, FIG. 2a is a view along the Y-Y line in FIG. 1b of an example of a conventional burner, Fig. 2b is a front view of the burner, Fig. 2c is a view taken along line A-A in Fig. 2b, Fig. 2d is a view taken along line B-B in Fig. 2b, Figure 2e is a perspective view of the burner nozzle, Figure 3a is a curve diagram showing the relationship between boiler load and combustion air amount, Figure 3b is a curve diagram showing the relationship between boiler load and burner wind box draft, and Figure 3a is a curve diagram showing the relationship between boiler load and combustion air volume. FIG. 4 is a curve diagram showing the relationship between the wind box damper and the damper resistance, FIG. 5 a is a view along the Y-Y line in FIG. 1 b of another example of a conventional burner,
Figure 5b is a front view of the burner, Figure 5c is Figure 5b
FIG. 5d is a view taken along line C--C in FIG. 5b, FIG. 6a is a front view of the burner according to the present invention, and FIG. The arrow view along the E-E line in Figure 6a and the arrow view in Figure 6c are F-F in Figure 6a.
It is an arrow view along a line. 1... Furnace, 2... Burner, 3... Wind duct, 4',
4'... Wind box damper, 5... Fuel supply pipe, 11...
...Gas burner nozzle, 12...Fuel gas nozzle,
13...Primary air nozzle, 14...Secondary air nozzle, 21...Gas burner nozzle, 22...Fuel gas nozzle, 23...Primary air nozzle, 31...Gas burner nozzle, 32...Fuel gas nozzle, 33
...Primary air nozzle, 34...Sub-primary air nozzle, 36, 37...Wind box damper.

Claims (1)

[Claims] 1. In the burner nozzle of a corner fire ear ring boiler using low calorie gas fuel, which corrects the imbalance of air volume of each burner by opening and closing the wind box damper, the fuel gas nozzle and the primary air nozzle through which combustion air flows are alternately connected. A secondary air nozzle is arranged between the alternatingly arranged fuel nozzles and the primary air nozzle in the fuel compartment, and a secondary air box damper is provided in the air passage. A burner nozzle characterized by: