JPH0317044B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a spretzder stoker used in a coal-fired boiler.

(Prior Art) In recent years, the number of coal-fired boilers with low fuel costs has been increasing in Japan, and unlike the coal-fired boiler era in the past, more and more coal is being imported from overseas.

Therefore, it is becoming difficult to obtain coal that has been cleaned to have a uniform particle size or a certain brand of coal, as was the case with domestic coal in the past.

By the way, there are problems in that most of the ordinary foreign coals have a high fuel ratio (fixed carbon/volatile matter), making it difficult to ignite, or that the grain size is uneven and there is a high proportion of fine coal mixed in.

Due to this situation, the adoption of spretzder stalkers is becoming more popular. This spreader stoker is composed of a reverse feed type moving bed stoker and a coal spreading device, and the coal is uniformly spread onto the stoker by the spreading device.

Since the above-mentioned spreader stoker spreads new coal onto the stoker on which a combustion layer has already been formed over the entire area, ignition is easy and the combustion speed is very fast, and the coal is not supplied. There is an advantage that it is possible to follow sudden load fluctuations by adjusting the amount of coal. Therefore, even relatively poor quality coal can be burned.

FIG. 3 is a schematic vertical cross-sectional view of a coal-fired boiler using a conventional spreader stoker.
6, a hopper 17, a combustion chamber 18, a superheater 19, a boiler main body 20, an air preheater 21, etc.

The amount of coal supplied from the hopper 22 is adjusted by the supply section 23 of the dispersion device 16, and the amount of coal supplied from the hopper 22 is adjusted by the dispersion section 24 of the dispersion device 16.
5 Spread it evenly on top. Above the stoker 15, an ash layer a', a combustion layer b', and a coal layer c' are sequentially formed from the bottom layer, and vigorous combustion occurs due to ventilation from below. Then, the ash falls and is discharged from the front of the stoker 15, and is discharged from the water-sealed ash removal device 25 to the ash removal conveyor 26.

On the other hand, the combustion gas is in the combustion chamber 18, the superheater 19,
Flue 2 via boiler body 20 and air preheater 21
It is discharged from 7. Further, combustion air is supplied from the forced draft fan 28 to the stoker 1 from the hopper 17 via the air preheater 21 and the air passage 29.

However, even in the above-mentioned spreader stoker, there is a problem in the position of the innermost part A' of the reverse feed type moving bed stoker 15.

That is, the scattered coal is in the innermost part of the stoker 15.
Since the stoker 15 is moving toward the front (in the direction of the arrow) even if it flies to A', neither the ash layer a' nor the combustion layer b' is formed at the innermost part A'. In other words, there is no spark. Therefore, in the innermost part A', ignition is performed by the radiation heat from the combustion chamber 18 and the fire transfer action of the coal seam c' on the stoker 15.

However, if the coal contains a lot of moisture or if it is poor quality coal with a high ash content, the ignition of the innermost part A' will be delayed. In this case, as shown in FIG. 4, an unignited coal seam D is formed due to the ignition delay. Once this happens, coal is sequentially spread over the coal seam D, so that islands D of unburned coal are formed as shown in FIG. This island D has poor ventilation from below, and as shown in Fig. 6, its height gradually increases, and a lump of unburned layer that has partially turned into tar forms at its base.

As a result, there was a problem in that conventional spletter stokers were unable to achieve smooth combustion due to the properties of the coal.

(Problems to be Solved by the Invention) The present invention has been devised to solve the above-mentioned problems, and its purpose is to provide a spreader stoker that allows smooth combustion at all times.

(Means for solving the problem) The spreader stoker of the present invention includes a reverse-feeding type moving bed stoker that moves from the back toward the front, and a reverse-feeding type moving bed stoker disposed at a position above the front of the reverse-feeding type moving bed stoker. The spletter stoker is equipped with an air box that supplies combustion air from a fan at the innermost part of the reverse-feed type moving bed stoker, and which constantly forms a bed of sparks in an inclined manner. It is characterized by the provision of an auxiliary grate for ignition.

(Operation) Coal is uniformly spread over the inverted bed type moving stoker and the auxiliary grate by the spreading device.

On the stoker, from the bottom layer, an ash layer, a combustion layer,
Coal seams are formed one after another, and vigorous combustion occurs due to ventilation from below.

In addition, since the auxiliary ignition grate always has a slanted spark layer formed on its upper surface, the coal sprinkled on the auxiliary ignition grate ignites and burns immediately, and gradually burns as the stoker advances. It will slide onto the stoker and form a spark layer on the stoker.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a schematic longitudinal sectional view of a spreader stoker showing an embodiment of the present invention, in which 1 is a reverse feed type moving bed stoker, 2 is a spreading device, and 3 is an auxiliary ignition grate.

The reverse feed type moving bed stoker 1 is disposed below the combustion chamber 4 of the coal-fired boiler, and is configured to move from the back toward the front (in the direction of the arrow), and below it is configured to move combustion air. Hopper 5 that supplies
is provided.

The spraying device 2 is installed in front of the boiler at a position above the stoker 1, and includes a hopper 6, a supply section 7, and a spraying section 8. Incidentally, a screw feeder is used in the supply section 7, and this is configured to be able to supply a fixed amount of coal in the hopper 6 to the dispersion section 8. Further, a rotor (rotary blade) is used in the dispersion section 8, and this is configured to uniformly spread the coal onto the reverse feed type moving bed stoker 1 and to adjust the reaching distance.

On the other hand, the auxiliary ignition grate 3 is arranged at the innermost part A of the reverse feed type moving bed stoker 1. That is, in this embodiment, an inclined fixed step grate is used as the auxiliary grate 3, and this is supported and fixed to a hook 10 provided on the rear water cooling pipe 9. In addition, an air box 11 is provided at the rear and lower part of the auxiliary grate 3,
The air box 11 includes an air passage 12 and a booster fan 1.
3 are connected. Further, the booster fan 13 is supplied with air preheated by the air preheater of the boiler. Furthermore, an inlet 14 is formed above the auxiliary grate 3 to feed firewood for ignition onto the auxiliary grate 3 at the time of starting the boiler.

The coal supplied from the hopper 6 passes through the supply section 7 of the dispersion device 2 and is uniformly scattered onto the reverse feed type moving bed stoker 1 and the auxiliary grate 3 by the dispersion section 8.

Above the stoker 1, an ash layer a, a combustion layer b, and a coal layer c are sequentially formed from the bottom layer, and vigorous combustion occurs due to ventilation from below. Then, the ash falls and is discharged from the front of the stoker 1.

In addition, since sparks are always formed on the upper surface of the auxiliary grate 3, the coal sprinkled on the auxiliary grate 3 is immediately ignited and burnt together with the radiant heat B from the combustion chamber 4, resulting in a stoker. 1 gradually slides onto the stoker 1 and forms a spark layer on the stoker 1.

As a result, the stoker 1 will have sparks throughout the entire area, and smooth combustion will occur.

In the above embodiment, a screw feeder was used for the supply section 7 of the dispersion device 2, and a rotor was used for the dispersion section 8, but the dispersion device 2 is not limited to the above embodiment. The supply section 7 may be drum-shaped, and the dispersion section 8 may be a shovel type or a compressed air type.

Further, in the above embodiment, a fixed step grate is used as the auxiliary grate 3, but the configuration of the auxiliary grate 3 is not limited to the above embodiment.

(Effects of the Invention) As described above, the spreader stoker of the present invention has a structure in which the auxiliary grate for ignition is disposed at the innermost part of the reverse feed type moving bed stoker. Sparks are formed, and the coal scattered at the innermost part of the stoker is immediately ignited and combusted by the sparks. As a result, even poor quality coal can be smoothly combusted over the entire stoker area, resulting in good and reliable combustion.

[Brief explanation of drawings]

Fig. 1 is a schematic longitudinal cross-sectional view of a spretzder stoker showing an embodiment of the present invention, Fig. 2 is a schematic longitudinal cross-sectional view of the main parts, and Fig. 3 is a coal-fired boiler using a conventional spretzder stoker. Schematic longitudinal sectional view of 4th
5 and 5 are plan views showing how coal is combusted by a conventional stoker, and FIG. 6 is a schematic side view of the stoker showing how coal is combusted by a conventional stoker. 1 is a reverse feed type moving bed stoker, 2 is a spreading device, 3 is an auxiliary fire grate, and A is the innermost part.

Claims (1)

[Claims] 1 In a spretsuda stoker consisting of a reverse-feed type moving bed stoker 1 that moves from the back toward the front, and a coal spreading device 2 disposed above the front of the reverse-feed type moving bed stoker 1. An auxiliary ignition grate 3, which is equipped with an air box 11 for supplying combustion air from a fan 13 and which constantly forms a stylus layer in an inclined manner, is disposed at the innermost part A of the reverse feed type moving bed stoker 1. Spretzdarstalker is characterized by the following: