JPS6021282B2 - Powder fuel combustion method - Google Patents

Description

[Detailed Description of the Invention] The method of pulverizing and burning solid fuel such as coal includes
There is a direct method in which fuel pulverized by a pulverizer is directly transported from the pulverized part to a burner and burned, and a pulverized fuel produced in a pulverizer is stored in a granule storage bunker and then stored in a burner. There are two types of combustion methods, one is an indirect type and the other is a direct type, which is used to supply granular fuel to the granular fuel.

As shown in FIG. 1, the conventional direct feeding type feeds hot air and raw material solids to a pulverizer 1 to generate a powder/gas mixture 2, which is directly fed into the burner of a combustion furnace 3. 4 and burn it. In the method immediately after the coal is crushed, a large amount of air is used to crush, dry, and separate the coal into lees powder in the crusher 1, and the air is used for transporting the powder and for combustion in the burner 4. Since it also serves as primary air, the amount of NOx produced is extremely large, and since the generation of N○x and unburned matter are caused by mutually contradictory causes, it is generally recommended to reduce NOx (lower the excess air ratio). There is a problem that unburned matter increases when the amount of primary air is decreased.

Therefore, the present invention provides a granular fuel combustion method that can control the amount of end combustion and N○× produced by exceeding the particle size and excess air ratio of the granular fuel supplied by each burner. It was made for the purpose of

Next, the present invention will be explained based on a first embodiment shown in FIG.

In FIG. 2, an air supply pipe 12 that supplies primary combustion air used as drying and transfer air is connected to the crusher 11, and the crusher 11 and the cyclone separator 1 are connected to the crusher 11.
3 are conveyed through the mixed flow transfer pipe 14. The upper part of the cyclone separator 13 is a burner 15 and a particulate fuel transfer pipe 1.
A venturi pipe 17 is attached to the lower part of the cyclone separator 13, and a branch pipe 18 branched from the middle of the air supply pipe 12 is connected to one end of the venturi pipe 17, and the other end is connected to the lees fuel. The burner 20 is connected via the transfer pipe 19. Further, each of the burners 15 and 20 passes through an auxiliary air supply pipe 21 and enters into the combustion furnace 22. The solid fuel C crushed by the crusher 11 becomes powder and granules, which mix with the primary combustion air sent from the air supply pipe 12 to form a mixed flow of powder and gas, which is transferred to the mixed flow transfer pipe 1.
4 to the cyclone separator I3. The powder sent to the cyclone separator 13 is separated into fine particles and coarse particles, the fine fuel is sent to the burner 15 through the fine fuel transfer pipe 16, and the hammer fuel is sent from the branch pipe 18. The coarse particles are sent to the burner 16 along with the primary air through the coarse particle transfer pipe 19, and are injected into the combustion furnace 22 where they are burned.

During combustion, the amount of unburned matter is generally greatly affected by the amount of coarse particles of 50 mesh or more in the fuel, so the branch pipe 18
The primary air from the fuel burner is adjusted and fed to increase the excess air ratio on the coarse fuel burner side for combustion.

It is possible to increase the excess air ratio only on the burner side for granule fuel, which makes it possible to control the sludge content, and by lowering the excess air ratio only on the burner side for granule fuel, it is possible to
The amount of ○× produced can be reduced. Furthermore, since the fuel is divided into powder and coarse particles midway through, there is no need to make the fuel particle size finer as a whole, and the power of the pulverizer can be saved.

Next, the present invention will be explained based on a second embodiment shown in FIGS. 3 and 4.

In the second embodiment, instead of the cyclone separator 13 that separates the powder into fine particles and coarse particles in the first embodiment, a pipe section 14' connected to the mixed flow transfer pipe 14 is used. A rotating vane 23 is disposed, and a branch pipe section 16' is connected to the fine particle transfer pipes 16 and 19, respectively, on the downstream side of the rotating vane 23.
, 19', and the inlet of the branch pipe section 16' is connected to the section 14'.
A separator 13' having a closed entrance is disposed at the center on the downstream side of the rotating vane 23.

By adjusting the angle of the swirling vanes 23 of this separator 13', the swirling strength is changed to form a mixed flow of fine particles with a small excess air ratio and a mixed flow of coarse particles with a large excess air ratio. The water is ejected from each burner 15, 20. Therefore, this method also has the same effects as the first embodiment, and also provides the following effects that are not seen in the first embodiment. There is no need for a new medium (air, etc.) to transport the lees, and if it is necessary to store the fine particles separately, it is necessary to install a collection cyclone, bag filter, etc., but the transport that was originally included Because some of the gas flows toward the coarse particles, the capacity of these devices is small, and when used for burning coal, etc.
Compared to the case of separation using a cyclone, the air/fuel ratio on the fine particle side can be made smaller, so lower N○k can be expected.

Although the present invention has been described above based on examples, the present invention is not limited to these examples. In the method of burning granular fuel in which the solid fuel is pulverized, it is separated into coarse fuel and granular fuel, each of which is conveyed separately by air, thereby reducing the excess air ratio of the granular fuel and reducing the amount of dregs. The present invention provides a granular fuel combustion method characterized by ejecting granular fuel into a furnace with a high air excess ratio, and by this method, granular fuel is separated into fine particles and coarse particles. However, by reducing the excess air ratio of the fine fuel and increasing the excess air ratio of the coarse fuel, it is possible to suppress the melon generated from the combustion of the fine fuel, and furthermore, the coarse particles remaining as unburned fuel can be suppressed. It is possible to completely burn granular fuel.

[Brief explanation of the drawing]

Fig. 1 shows a conventional powder combustion device, Fig. 2 shows a first embodiment of the present invention, Fig. 3 shows a second embodiment of the present invention, and Fig. 4 is an enlarged view of section W in FIG. 3. 1,11...Crusher, 3,22...Combustion furnace, 4,15,20...Burner, 12...
... Air supply pipe, 13 ... Cyclone separator, 14 ... Mixed flow transfer pipe, 16 ... Fine particle transfer pipe, 17 ... Venturi Tube, 18...
... Branch pipe, 19 ... Coarse particle transfer pipe, 21 ... Auxiliary air supply pipe, 13' ... Separator, 23 ... Swivel vane, 24
...Sekiguchi. Younger brother' figure 2 figure 3 silk figure 4

Claims (1)

[Claims] 1. In a granular fuel combustion method in which solid fuel is pulverized, transported by air, and ejected into a furnace together with the air for combustion, after pulverizing the solid fuel, the solid fuel is separated into coarse granular fuel and fine granular fuel. A granular fuel combustion method characterized in that the granular fuel is separately conveyed by air, and the granular fuel is injected into a furnace with a low excess air ratio and a coarse granular fuel with a high excess air ratio.