JPS603128B2 - Cinder reburning device in spretsuda stoker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a cinder reburning device in a spretzer stoker, and the cinder in the collected combustible gas is transferred to the starting end of the reverse feeder stoker. This invention relates to a cinder reburning device that completely burns raw coal at the initial end of a stoker and prevents cinder from scattering again by sequentially supplying raw coal through a chute.

Recently, due to soaring oil prices and concerns about future supply, the use of coal as an alternative fuel has been reconsidered in various fields.

However, due to the depletion of domestic coal and the cost, we have no choice but to rely on imported coal for most of this alternative fuel. On the other hand, a large amount of recently imported coal is so-called cut coal produced by open-pit mining, and most of it is shipped without being washed, unlike conventional domestic coal. Therefore, the mixing ratio of pulverized coal is extremely high compared to domestic coal, creating the problem that ideal ventilation cannot be obtained with conventional chain beds or transfer stokers, making it extremely difficult to achieve a uniform combustion pattern. There is. In order to solve these problems, the use and development of a so-called spreader stoker that burns imported coal, which replaces the conventional chain bed or moving bed type stoker, is currently being actively promoted in various fields. .

Figure 1 shows a typical example of this type of spreader stoker. is the combustion chamber, 6 is the boiler body, 7 is the cinder separator, 8 is the economizer, 9 is the air heater, and 1 is the flue.

By the rotation of the scattering and immersing machine 3, the coal A is uniformly scattered onto the reverse feed stoker 4, and the fine granulated coal particles B contained therein are spatially combusted while floating in the combustion chamber 5.

The pulverized coal grains B continue to rise while burning and enter the boiler body 6 together with the combustion gas, where they are subjected to a reverse separation action and separated from the exhaust gas, and are recovered as cinder C in the hopper 11.

Furthermore, the pulverized coal particles B remaining in the exhaust gas are separated again near the point by the cinder separator 7 installed at the outlet of the boiler body 6 and the denominator of the bonito path 9, and are separated as cinders C2 and C3. It is deposited into each hopper 12 and 13. In this type of spreader stoker, unlike the conventional pulverized coal combustion equipment, relatively coarse coal particles are scattered, so that the cinder C collected in the hoppers 11 and 12 is , C2 will contain a large amount of unburned matter.

Therefore, the collected cinders C, , C2 containing a large amount of unburned materials
is re-injected into the furnace by the cinder reburning leech device D, and is floatingly burned within the furnace again. Incidentally, the cinder C3 accumulated in the hopper 13 has extremely fine particles and has a large ash content, so it is normally exhausted and dumped without being reburned. In addition, in Fig. 1, 14' is a re-blowing fan, 15 and 16 are rotary dampers, and 17 and 18 are
is the blowing conduit. However, in the conventional spreader stoker equipped with the cinder re-blowing device D as described above, the following serious problem remains to be solved.

The first problem is dust loading caused by re-injected cinder.

The components of the cinder that are reinjected into the furnace are mainly fixed carbon and ash, and the volatile components have already been burned out.

As a result, short combustion such as space combustion within the combustion chamber 5,
Due to the residence time, complete combustion of the cinder becomes extremely difficult, and the dust loading of the dust collector becomes excessive.
There is a tendency to cause fly ash adhesion and wear of boiler water pipes. The second problem is that the reverse feed stoker 4
This is a problem related to poor ignition of coal at the beginning of the process.

The spreader stoker is constructed so that the coal is spread extremely uniformly on the stoker, and as shown in FIG. 4a, and the residence time in the furnace is made longer.

As the reverse feed stoker 4 moves in the direction of the arrow, the ash layer Y becomes thicker and the combustion layer Burn.

Further, since the coal A is successively scattered onto the combustion bed X, the drying and ignition of the coal A are extremely quick, and the burning speed of the coal is significantly faster than that of a chain bed or a moving bed stoker. However, in FIG. 2, if E is the combustion zone and F is the ash zone, then the portion G (near the initial end 4a of the stoker) will form a layer of raw coal A' only.

That is, there is almost no ash layer Y at the stoker initial end 4a, and undried raw coal A' having a relatively large particle size is directly scattered and deposited on the stoker surface. As a result, unlike the combustion zone E, which is ignited relatively quickly by the spark in the lower layer, near the initial end 4a of the stoker, there is no spark below, so ignition must occur only by horizontal spark transfer. It will not happen. Therefore, due to the large particle size of the injected coal, the stoker initial end 4
There is a drawback that the ignition of the coal near a is delayed and the coal cannot be burned uniformly over the entire area on the stoker 4. The present invention aims to solve the above problems in the conventional spreader stoker equipped with this type of cinder reburning device, and uses a reblowing fan 14 to transport cinder into the furnace by air transport. By sequentially supplying high-temperature cinder to the starting end 4a of the reverse feed stoker 4 through the cinder supply shoe without directly blowing the recovered high-temperature cinder, the high-temperature cinder is transferred to the starting end 4a.
Raw coal A can be
The aim is to speed up the ignition of cinder and completely prevent problems such as dust loading caused by re-injection of cinder. Hereinafter, the details will be explained based on each embodiment of the present invention shown in FIGS. 3 to 5.

It should be noted that the present invention is not limited to the configurations of the embodiments, but can be modified as appropriate without departing from the spirit of the invention.

Also, the same reference numbers are used for parts common to FIGS. 1 and 2. FIG. 3 shows an outline of a spreader stoker equipped with a cinder reburning bran device according to the present invention, and FIG. 4 explains its operation. Third
In the figure, reference numerals 15 and 16 indicate rotary dampers, and the cinders C, C2 fed out from the rotary dampers 15 and 16 are transferred to a cinder hopper 20 by a screw feeder 19, and then
The cinder is supplied to the starting end 4a of the reverse feed stoker 4 through a gap in the water tube wall 23 via the cinder supply chute 22.

By supplying the cinders C, C2 to the stoker initial end 4a, the top of the reverse feed stoker 4 becomes a state in which a cinder layer Z, an ash layer Y, and a combustion layer X are stacked, as shown in FIG. High-temperature cinders C, C2 are mixed into the large raw coal A' to be boiled and serve as a "sparkling seed", and the raw coal A' is heated uniformly and at a uniform speed. It will be burned.

Further, the supplied cinder C is sufficiently mixed with the raw coal A′ rich in volatile matter on the stoker 4 without being burned in space in a floating state, and is retained on the stoker for a long time and burned. Therefore, even if the fixed carbon content is large, it will be completely combusted.

As a result, the generation of fly ash is prevented, and so-called dust loading in the dust collector provided in the boiler body and the bonito path is also prevented. FIG. 5 shows an outline of a spreader stoker according to another embodiment of the present invention, in which a direct collection method of cinder is adopted.

In the figure, 15 and 16 are rotary dampers, and 22 is a cinder supply chute, and in this system, the cinder C being burned is directly supplied to the starting end 4a of the reverse feed stoker 4. Therefore, the various effects of the present invention described above become even more remarkable. As described above, the present invention has a structure in which the recovered overflowing cinder C is sequentially supplied to the initial end 4a of the reverse feed stoker 4 via the cinder supply/joining chute 22. It is possible to quickly and uniformly completely burn the large-grained raw coal A' at the end portion 4a, and it is also possible to completely reburn the cinder containing a large amount of fixed carbon. This has an extremely excellent practical effect of completely preventing loading problems.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an outline of a spreader stoker equipped with a conventional cinder reburning device, and FIG. 2 is an explanatory diagram of its operation. FIG. 3 is a sectional view showing an outline of a spreader stoker equipped with a cinder rekindling ant device according to the present invention;
The figure is an explanatory diagram of its operation. FIG. 5 is a schematic cross-sectional view showing a second embodiment of the present invention. 1' coal feeding hopper, 2
3 is a metering feed combining tray, 3 is a coal scattering feeder, 4 is a reverse feed stoker, 4a is the first end of the stoker, 5 is a combustion chamber, 6 is a boiler body, 7 is a cinder separator, 8 is a coal saver, 9 is an air ripening device, IQ is a katsuodo, 11, 12, 13, 20 is a hopper.
, 15, 16, 21 are rotary dancers/1, 19 is a screw feeder, 22 is a cinder combined chute, 2
3 is water pipe wall, A, A' is raw coal, B is pulverized coal, C, C,
, C2, C3 are cinders, D is cinder reburning device, E
is the combustion zone "F' is the ash zone, X is the combustion layer, Y is the ash layer,
Z is cinder layer. Figure 1 Figure 2 Figure 4 Figure 3 Figure 5

Claims (1)

[Scope of Claims] 1. High-temperature cinder C separated and recovered from the combustion exhaust gas is sequentially supplied to the initial end 4a of the reverse feed stoker 4 by the cinder supply chute 22, and the high-temperature cinder C is introduced into the spread raw coal A'. A cinder reburning device in a spretzdar stoker that allows cinder to be mixed into the interior. 2. Cinder C_1 separated and recovered within the boiler body 6 and/or cinder C_2 recovered by the cinder separator 7 provided at the boiler exhaust gas outlet are directly supplied in a combusted state to the initial end 4a of the reverse feed stoker 4. A cinder reburning device in a spretzer stoker according to claim 1.