JP2735643B2 - Pulverized coal combustion equipment - Google Patents

Description

The present invention relates to a pulverized coal combustion device for burning pulverized coal,
Particularly, the present invention relates to a pulverized coal burner which can stably burn the pulverized coal concentration even at a low load.

[Prior Art] For example, in a business-use boiler for a thermal power plant, a change in fuel situation has actively switched from petroleum fuel to coal fuel. On the other hand, fluctuations in power demand at power plants,
For example, the power generation load of the power plant fluctuates considerably due to the seasonal difference between summer and winter, the difference between weekdays and holidays, and the like. This is due to the recent trend of nuclear power plants generating more power,
A so-called DSS that operates a large-scale boiler for a thermal power plant to operate as a base load, and to operate a large-scale boiler for a thermal power plant that previously operated at a constant load for the base load.
There is a need to drive.

FIG. 5 is a schematic configuration diagram of a pulverized coal combustion device. Coal fuel is supplied from a coal bunker 1 through a coal feeder 2 to a mill 3. In the mill 3, the coal fuel is pulverized and dried, classified, and conveyed by hot air from the primary air fan 4. The pulverized coal is supplied from the pulverized coal pipe 5 to the furnace 7 via the pulverized coal burner 6, and is mixed with the secondary and tertiary air supplied from the wind path 8 and the wind box 9 to be burned.

In FIG. 5, reference numerals 10 and 11 are primary and secondary air preheaters, and 12 is a blower.

In the pulverized coal combustion apparatus described above, the supply of coal fuel to the mill 3 is supplied in proportion to the load factor, whereas the amount of primary air is limited by the accumulation of pulverized coal in the pulverized coal pipe 5. Even if the load of the mill 3 is 50% or less, the air is supplied so as to maintain 70% of the maximum load air supply amount for the purpose of prevention and the backfire from the pulverized coal burner 6.

As described above, when the load of the mill 3 becomes low, the amount of pulverized coal is reduced in proportion to the load. The ambassador, and the primary air amount is at least about 70% of the maximum load for the reason described above. The ratio of the amount of pulverized coal is smaller than that of.

That is, C / A, which is the ratio between the primary air amount (transporting air amount A) and the pulverized coal amount (C), becomes low, which is not preferable at a low load when the DSS operation is performed.

For this reason, when the load of the mill 3 is low, a cyclone separator 15 is arranged as shown in FIGS. 6 and 7 in order to increase C / A as much as possible.

6 and 8 are enlarged sectional views of the vicinity of the fine powder burner in FIG.

6 and 7, reference numeral 5 is a pulverized coal pipe, 6 is a pulverized coal burner, 7 is a furnace, and 9 is a wind box, which is the same as that in FIG.

In the figure, reference numeral 13 denotes a high-concentration conveying pipe constituting the main body of the pulverized coal burner 6, and a low-concentration conveying pipe 14 is arranged in the high-concentration conveying pipe 13 so that the central axis is substantially equal.
Reference numeral 15 denotes a cyclone separator connected to the base of the high-concentration transport pipe 13, that is, the upstream side of the pulverized coal flow path. Inside the cyclone separator 15, a control sleeve 16 is disposed at the end of the low-concentration transport feeling 14, and hydraulic pressure, air pressure, etc. The low-concentration transport pipe 14 can be moved in the axial direction by a driving device 17 via a rod 18. Reference numeral 19 denotes a bellow for maintaining the airtightness of the connection between the control sleeve 16 and the low-concentration transport pipe 14. The pulverized coal pipe 5 is connected to the cyclone separator 15 in the connection direction as shown in FIG.

In such a structure, the pulverized coal C in the pulverized coal pipe 5 flows in the tangential direction of the cyclone separator 15 to form a swirling flow in the cyclone separator 15. As a result, the pulverized coal C transported by air flow moves to the inner peripheral wall side of the cyclone separator 15, and a considerable amount of the pulverized coal C enters the outer passage 20 between the low-concentration conveying pipe 14 and the high-concentration conveying pipe 13. Inflow. On the other hand, the amount of pulverized coal flowing into the control sleeve 16 decreases relatively, and the concentration of pulverized coal in the inner passage 12 decreases. That is, a lean jet having a low pulverized coal concentration is injected from the center of the pulverized coal burner 6 into the furnace 7, and a dense jet having a high pulverized coal concentration is injected from the periphery thereof. In other words, even if the pulverized coal concentration is reduced as a whole with respect to the pulverized coal burner 6, since a jet having a high pulverized coal concentration is jetted in a layered manner by classification by the cyclone separator 15, the ignitability is high on the high concentration side and the low concentration is low. On the other hand, the atmosphere is surrounded by the high-concentration-side flame 22, so that the ambient temperature is high, and even at a low concentration, the ignitability is improved, and the ignitability as the pulverized coal burner 6 is improved.

However, when the fluid and solid conditions change (as an operation load) as in the case of a low load,
Since the flow velocity is lower than the optimum flow velocity, the classification and trapping of the pulverized coal deteriorates as shown by the curve A in FIG. 4, thereby defeating the original purpose, and the fine particles inside the pulverized coal are easily transported to the air flow. On the high-concentration transport pipe 13 side, fine particles in pulverized coal are less likely to be composed of coarse particles.

For this reason, high-concentration transport pipes 13 with less fine particles in pulverized coal
The side is unfavorable because it tends to be flame retardant.

[Problems to be Solved by the Invention] The conventional cyclone separator has a drawback that the range of use is narrow because no consideration is given to classification and collection performance when the load changes.

The present invention is intended to solve such conventional disadvantages, and its object is to maintain classification and collection performance over a wide range even at a low load, and to reduce pulverized coal at a low differential pressure. It is an object of the present invention to obtain a pulverized coal combustion apparatus capable of classifying and collecting the coal.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention provides a classified concentration adjusting path divided into a high concentration side flow path and a low concentration side flow path near a pulverized coal burner, and And a collector which is inclined from the low concentration side flow path to the high concentration side flow path in the classification concentration adjuster.

[Operation] The pulverized coal flowing from the pulverized coal pipe is divided into a high-concentration side flow path and a low-concentration side flow path at the entrance of the classifying concentration controller, and the pulverized coal divided into the high-concentration side flow path and the low-concentration side flow path. Moves to the high concentration side flow path along the inclination of the collector, so that a high C / A pulverized coal stream can be obtained even at a low load.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. First
The figure is a longitudinal sectional view of a classification concentration controller according to an embodiment of the present invention,
FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1, FIG. 3 is a vertical cross-sectional view of a classifying concentration controller showing another embodiment, FIG. FIG. 4 is a characteristic curve diagram showing

1 to 3, reference numeral 5 denotes a pulverized coal pipe, and 6 denotes a pulverized coal burner which is the same as a conventional one.

As shown in FIG. 1, pulverized coal C
Is a carrier gas and is guided to the classification concentration adjuster 23 by the pulverized coal pipe 5.

The solid-gas two-phase flow adjusted to a predetermined concentration by the classification concentration adjuster 23 is taken out by the high concentration side channel 25 and the low concentration side channel 24 and sent to the pulverized coal burner 6 installed on the downstream side. The pulverized coal burner 6 has a high concentration of pulverized coal, and the more fine particles in the pulverized coal, the more stable the fuel can be achieved. Supply.

The classifying concentration controller 23 has a low concentration side flow path 24 and a high concentration side flow path.
Each of the flow paths is divided into 25 flow paths and is separated by a partition plate. For example, the second passage from the low concentration side passage 24 to the high concentration side passage 25
As shown in the figure, a U-beam collector 27 is arranged inclined with respect to the flow path, and it is convenient for the pulverized coal to flow from the low-concentration side flow path 24 to the high-concentration side flow path 25 through the U-beam groove. The collector 27 has a slope, and only the pulverized coal is collected by the collector 27. Therefore, only the pulverized coal conveyed to the gas without being collected by the collector 27 on the low-concentration side flow path 24 side becomes a low-concentration pulverized coal gas stream. On the other hand, the pulverized coal in the low-concentration side channel 24 collected by the collector 27 flows into the high-concentration side channel 25 and flows into the solid-gas two-phase flow in which the concentration is higher than the concentration at the inlet of the classification concentration controller 23. Is obtained. The gas passing through the high-concentration-side flow path 25 is adjusted by the damper 28, and the gas sent to the high-concentration transport pipe 13 can be any high-concentration pulverized coal stream.

As described above, the collector 27 of the classifying concentration controller 23 is effective when the load is low such as DSS operation, since the trapping efficiency becomes better as the inlet flow path is slower as shown by the curve B in FIG.

Further, the collected pulverized coal can be easily guided only to the other high-concentration side channel 25 by the collector 27 of the inclined labyrinth beam.

The labyrinth of the collector 27 can be further improved by providing the collector 27 in a plurality of stages according to the collection efficiency arranged in two stages as shown in FIGS. 1 and 2. Can be.

FIG. 3 is a sectional view of a classifying concentration adjuster showing another embodiment.

In FIG. 3, the whole amount passes through the labyrinth collector 27 from the low concentration side channel 24 arranged on the left and right sides, and the pulverized coal is passed through the partition plate 26 into the high concentration side channel 25 located at the center. It collects collected particles. A part of the gas in the low-concentration flow path 24 whose concentration has been reduced by the labyrinth is adjusted to an opening degree of the slide damper 29, and a required amount is introduced into the high-concentration flow path 25, so that the solid-gas A phase flow can be obtained. Further collector
Since the gas that has passed through 27 is introduced into the high-concentration side channel 25, the pulverized coal that has slipped out of the collector 27 can be
By connecting the high-concentration side channel 25 and the high-concentration conveying pipe 13 of the pulverized coal burner 6, the high-concentration and large amount of pulverized coal fine particles are provided, so that a greater flame holding effect can be obtained. Can demonstrate.

[Effects of the Invention] According to the present invention, a high-concentration pulverized coal stream can be obtained even when the flow rate is low in the low-load embodiment, so that the DSS operation can be performed, and since the pressure difference is low, the local pressure is low. Less ash cuts.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view according to an embodiment of the present invention, and FIG.
FIG. 3 is a longitudinal sectional view showing another embodiment, FIG. 4 is a characteristic curve showing collection efficiency on the vertical axis, and flow velocity on the horizontal axis, and FIG. Schematic configuration diagram of pulverized coal combustion device, sixth
The figure is an enlarged sectional view near the pulverized coal burner in FIG. 5, and FIG. 7 is a transverse sectional view taken along the line VII-VII in FIG. 5 ... pulverized coal pipe, 6 ... pulverized coal burner, 13 ... high-concentration transport pipe, 14 ... low-concentration transport pipe, 15 ... cyclone separator, 23 ... classified concentration adjuster, 24 ... low-concentration side Channel, 25…
… High concentration side channel, 27… Collector.

Claims (1)

(57) [Claims] A cyclone separator is provided between a pulverized coal pipe and a pulverized coal burner for pneumatically transporting pulverized coal, and a rich and dilute pulverized coal stream in the cyclone separator is supplied to a high-concentration transfer pipe and a low-concentration transfer pipe of the pulverized coal burner. A classifier which is divided into a high concentration side flow path and a low concentration side flow path in the vicinity of the pulverized coal burner; and the low concentration in the classification concentration adjuster is provided. A pulverized coal combustion device comprising a collector that is inclined from a side flow path to a high concentration side flow path.