JPS6350569Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Background of the Invention] The present invention relates to a gas combustion device, and particularly relates to a gas combustion device that reduces nitrogen oxides (NO _x ) in exhaust gas in a full load range.

In recent years, as the demand for power generation has increased, boilers that use fossil fuels as their main fuel have become larger, and the influence of power generation boilers on air pollution is also increasing.

Emission regulations for _NOx , which accounts for a large proportion of the pollutants that increase air pollution, are becoming stricter year by year. Under these circumstances, Japan's power generation industry, which had been using petroleum as its main fuel since the second oil shock, has shifted to cheaper and more abundant coal fuels and cleaner gaseous fuels (LNG, LPG). It's coming.

However, as boilers have become larger, boilers have been started and stopped repeatedly on a daily basis in order to perform frequent load changes in response to power generation demand in order to reduce power generation costs.

As a feature of recent electricity demand, as nuclear power generation grows, the difference between maximum and minimum loads also increases.
There is a trend to shift boilers for thermal power generation from base load to load adjustment, and these boilers are operated at variable pressure by changing the pressure according to the load.
By using a variable pressure boiler that operates in a so-called supercritical pressure region at full load and in a subcritical pressure region at partial load, the power generation efficiency at partial load can be improved by several percent.

However, in conventional gas combustion equipment, the target cannot be reached at full load using a two-stage combustion method.
Although it is possible to reduce the NO _X value to below 1/4,
At partial loads such as 1/2 and 3/4 loads, it is not possible to reduce the _NOx value below the target NOx value.

[Prior art]

Figures 1 and 2 are diagrams explaining the two-stage combustion method. Figure 1 is a vertical cross-sectional view of the boiler, Figure 2 is a side view taken along the - line in Figure 1, and Figures 3 to 7 are views of the conventional boiler. This shows the gas combustion device. Figure 3 is a detailed view of the main burner and auxiliary burner, Figure 4 is a side view of Figure 3, and Figure 5 is a detailed view of the main burner and auxiliary burner.
6 and 6 are perspective views showing the tips of the gas elements of the main burner and the auxiliary burner, and FIG. 7 is a view showing the combustion state of the gas elements.

As shown in FIGS. 1 and 2, the gas combustion device applied to the conventional two-stage combustion method includes main burners 4, 5. The sub-burner 6 and the after-air port 7 provided above the sub-burner 6 and the exhaust gas recirculation port 8 provided at the bottom of the furnace 1
It was composed by. (In those that adopt the opposed combustion method, the main burners 4 and 5, the auxiliary burner 6, and the after air port 7 are provided on the rear wall 3 in the same way as the front wall 2.) In such a gas combustion device, the burner section is equipped with air For example, the ratio (actually supplied air amount/theoretically required air amount) is 0.6 to 0.6 for main burners 4 and 5.
1.0, and 0.4 to 0.6 for the auxiliary burner 6, and low _NOx combustion is performed under these conditions.

In this case, the main burners 4 and 5, which have a relatively large amount of air,
The _NOx generated in the combustion area of the auxiliary burner 6 is reduced to _N2 by contacting the reducing radicals generated in the combustion area of the auxiliary burner 6, where there is an excess of fuel.
_NOx conversion can be measured. Although the combustion exhaust gas from the furnace 1 contains a large amount of unburned matter, it is undesirable from the viewpoint of environmental conservation and thermal efficiency to release this directly into the atmosphere. By supplying combustion air from 7 and 7, complete combustion of unburned matter is ensured.

On the other hand, the main burners 4 and 5 and the sub burner 6 are
As shown in the figure and FIG.
It is constituted by an assembly of eight gas elements 10 arranged in a circular shape within a burner throat 9 bored in the burner throat 9 .

That is, as shown in FIG. 5, the gas element 10 has a main fuel nozzle 11a and an auxiliary fuel nozzle 11b that provides a flame-holding effect.
As shown in FIG. 6, gas elements 10b having only main fuel nozzles 11a are arranged alternately, and a flame stabilizing plate 12 is arranged in the center.

The ends of each gas element 10a, 10b are connected to the gas distribution pipe 13.
is connected to a fuel pipe 16 via a gas source valve 14 and a flow rate adjustment valve 15.

Further, combustion air 17 is supplied into the furnace 1 from the burner throat 9 via an air register 18 .

However, in a gas combustion apparatus that employs such a conventional two-stage combustion method, the gas elements 10 of the main burners 4, 5 and the auxiliary burner 6 are closed at full load.
Since all of a and 10b are burned, it is possible to reduce _NO It is necessary to reduce the number of burning burners (hereinafter referred to as combustion burners) such as burners 4, 5 and auxiliary burners 6, and increase the number of extinguished burners (hereinafter referred to as extinguishing burners).

For example, Fig. 7 shows the main burners 4 and 5 at 1/2 load in the burner arrangement of the gas combustion device as shown in Fig. 2.
The number of gas elements of the combustion burner and the extinguishing burner of the auxiliary burner 6 is illustrated.

In the figure, white circles indicate that all eight gas elements are combustion burners, and black circles indicate that all eight gas elements are extinguishing burners.
In FIG. 7, for convenience of explanation, the columns are called a row, b row, etc. from left to right in the figure, and the main burners 4, 5 and sub burners 6 of the a row are called 4a, 5a, 6a.

In other words, at 1/2 load, the number of combustion burners and extinguishing burners must be approximately half, and for low _NOx combustion at 1/2 load, rows a, c,
Main burners 4a, 5a, 4c, 5c in e row and g row,
4e, 5e, 4g, 5g and sub burners 6a, 6
The eight gas elements c, 6e, 6g are all combustion burners, and the main burners 4b, 5b, 4d, 5d, 4f, 5f, 4h, in rows b, d, f, h,
All eight gas elements of 5h and auxiliary burners 6b, 6d, 6f, and 6h were operated as extinguishing burners.

However, in the case where combustion burners and extinguishing burners are arranged alternately during partial load as shown in Fig. 7, even if we try to achieve low _NO , the disadvantage is that the combustion gas containing NO _x generated in the main combustion area of the main burners 4 and 5 cannot pass through the extinguishing burner area (black circle area) of the auxiliary burner 6 to perform substantial low NO _x combustion. It was hot.

In other words, the main burners 4a, 5a, 4c, 5c, 4
This is because the combustion gases e, 5e, 4g, and 5g rise and pass through the extinguishing burner areas of the auxiliary burners 6b, 6d, 6f, and 6h, where the flow resistance is the lowest.

[Purpose of the invention] The present invention attempts to eliminate the drawbacks of the conventional technology, and its purpose is to provide a gas combustion device that can perform low _NOx combustion even under partial load. It is.

[Key points of the idea]

In order to achieve the above-mentioned purpose, the present invention divides the fuel piping into the fuel piping for the main burner and the fuel piping for the auxiliary burner, and also installs an on-off valve in the gas element of the auxiliary burner. The present invention is characterized in that at least one gas element of the auxiliary burner is ignited even if the amount increases.

[Example of idea]

Embodiments of the present invention will be described below with reference to the drawings.
Fig. 8 is a longitudinal sectional view of the main burner and auxiliary burner of the present invention, which corresponds to the conventional Fig. 3, and Fig. 9 shows the combustion burner and extinguishing of the main burner and auxiliary burner of the present invention, which corresponds to the conventional Fig. 7. It is a figure showing the state of a burner.

In FIGS. 8 and 9, numerals 1 to 18 indicate the same parts as the conventional ones.

19 and 20 are main burner fuel pipes for the main burners 4 and 5 and sub-burner fuel pipes for the sub-burner 6;
1 and 22 are gas source valves and flow rate regulating valves of the main burner fuel pipe 19; 23 are on-off valves provided for each gas element 10a, 10b of the sub-burner 6; 24,
Reference numeral 25 indicates a gas source valve and a flow rate adjustment valve of the sub-burner fuel pipe 20.

In such a structure, the difference between the conventional gas combustion apparatus shown in FIG. 3 and the gas combustion apparatus of the present invention shown in FIG. However, in the gas combustion apparatus of the present invention, the main burners 4 and 5 are connected to the main burner fuel pipe 19, and the sub burner 6 is connected to the sub burner fuel pipe 19, as shown in FIG. 20, and an on-off valve 23 is provided for each gas element 10a, 10b, . . . of the sub-burner 6.

In other words, as explained in Fig. 7, in the conventional gas combustion apparatus, for example, at 1/2 load, the combustion burner and extinguishing burner are operated with approximately half the number, but in the gas combustion apparatus of the present invention, as shown in Fig. 9. As shown, the main burners 4a, 5a, 4c, 5c,
4e, 5e, 4g, 5g are combustion burners, 4b,
Even if 5b, 4d, 5d, 4f, 5f, 4h, 5h are extinguishing burners, the sub burners 6a, 6b, 6c,
6d, 6e, 6f, 6g, and 6h all have 8 gas elements, 4 of which are always combustion burners, and the other 4
The point is that books are fire burners. (The half-black color of the auxiliary burner 6 in FIG. 9 indicates the ratio of the gas elements that are burning and the gas elements that are extinguished.)

In this way, in the gas combustion device of the present invention, some of the gas elements 10a, 10b of the auxiliary burner 6 are always combusting even during partial load, so the main combustion area by the main burners 4, 5 is generated with
Since the combustion gas containing _NOx passes through the combustion burner area (semi-black area) of the auxiliary burner 6, low _NOx combustion can be performed.

In addition, in the embodiment of the present invention, the main burners 4a, 5a, 4c, 5c, 4e, 5
All the gas elements e, 4g, 5g burn, and the main burners 4b, 5b, 4d, 5d, 4f, 5
Although only the case where all gas elements of f, 4h, and 5h are extinguished and half of the gas elements of auxiliary burners 6a to 6h are burnt has been described, the present invention is not limited to this embodiment. All burners 5 may be extinguished, all main burners 4 may be combusted, and half of the gas elements of auxiliary burners 6a to 6h may be combusted, and the same applies to burning gas at 1/4 load and 3/4 load. Various combinations of elements and extinguishing gas elements may be used; in short, if at least one gas element in the sub-burner 6 is combusted, low _NO .

[Effect of idea]

According to the present invention, low _NOx combustion can be achieved regardless of whether it is under full load or partial load, and various combustion conditions can be selected by particularly combining the number of gas elements in the main burner and auxiliary burner.

[Brief explanation of the drawing]

Figures 1 and 2 are diagrams explaining two-stage combustion. Figure 1 is a sectional view of the boiler, Figure 2 is a side view taken along the - line in Figure 1, and Figures 3 to 7 are diagrams for conventional gas combustion. This shows the combustion device, and Figure 3 shows the conventional main burner,
FIG. 4 is a side view of FIG. 3, FIGS. 5 and 6 are perspective views showing the tips of the gas elements, and FIG. 7 is a detailed longitudinal sectional view of the sub-burner. Figures 8 and 9 showing the combustion state show the gas combustion device of the present invention, where FIG. It is a figure which shows the combustion state of the gas element of a main burner and a sub burner. 4, 5... Main burner, 6... Sub burner, 10... Gas element, 16... Fuel pipe, 19... Fuel pipe for main burner, 20... Fuel pipe for sub burner, 23... Open/close valve.

Claims (1)

[Scope of utility model registration request] A sub-burner consisting of multiple gas elements is placed above the main burner consisting of multiple gas elements, and both burners are connected to a fuel pipe with a gas main valve to direct _NOx from the main burner to the sub-burner. In those that are reduced by combustion gas from
The fuel piping is divided into the fuel piping for the main burner and the fuel piping for the auxiliary burner, and an on-off valve is provided for the gas element of the auxiliary burner, so that even if the number of extinguishing burners of the main burner increases when the load changes, the gas element of the auxiliary burner remains unchanged. A gas combustion device characterized by having at least one ignited gas.