JP2519923B2 - Pulverized coal combustion equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pulverized coal combustion apparatus, and more particularly, to a structure of a pulverized coal burner capable of naturally producing pulverized coal up to a low load without auxiliary combustion.

[Prior Art] In combustion furnaces such as boilers that burn pulverized coal to generate power, similar to oil and gas-fired combustion furnaces, from the load demand balance (1) the seasonal difference between summer, winter and spring-autumn, Weekdays /
To reduce the minimum load that corresponds to the difference in power demand due to the difference between holidays and day and night, for example, up to 20% of the boiler load), (2) When reducing the minimum load, to reduce the fuel cost, use auxiliary fuel or There is a demand for reducing the amount of heavy oil or gas used as a fire source as much as possible.

In response to such a demand, the present inventors have previously disclosed in
The pulverized coal burner described in 61-285306 was proposed. This pulverized coal burner uses fuel 10 (pulverized coal) as shown in FIG.
Is crushed, dried, in a pulverized coal machine (not shown).
After being classified, it is supplied from the pulverized coal pipe 15 to the pulverized coal burner nozzle 5 through the cyclone separator 19 facing the wind box 2.

A sleeve 22 is arranged in the cyclone separator 19, and a vent amount control damper 21 is installed in the middle of a pipe line connecting the sleeve 22 and the vent pipe 20. Therefore, the C / A (coal / primary air) ratio of the pulverized coal burner nozzle 5 on the downstream side of the cyclone separator 19 is determined by the vent amount control damper 2
It is controlled by adjusting the opening of 1.

Therefore, in the low load range, the pulverized coal burner nozzle 5 ejects the pulverized coal fuel having a high concentration by increasing the C / A ratio of the fuel, and the radiant heat in the furnace due to the flame holding ring 14 increases the temperature of the pulverized coal. It is effectively used to shorten the ignition time, that is, to secure flame holding.

Further, the vent air 9 that has passed through the sleeve 22 in the cyclone separator 19 and contains a small amount of pulverized coal passes through the vent amount control damper 21 and the vent pipe 20, and then the burner throat.
It is blown into the furnace from a vent burner 23 arranged at a position separated from the outer peripheral edge of 12 and burned and burned by the radiant heat of the pulverized coal flame 13. And the size of Venturi 6, pulverized coal burner nozzle 5, vent pipe 2
0, by properly selecting the sands etc. of the vent burner 23, the fuel C /
Consideration is given so that A can be controlled.

[Problems to be solved by the invention]

In the pulverized coal burner as described above, for example, when the load of the burner decreases, a cyclone separator is used.
The flow rate of the vent air 9 in the vent pipe 20 decreases as the air volume passing through 19 decreases. Therefore, a small amount of pulverized coal contained in the vent air 9 is partially deposited in the vent pipe 20,
In addition to hunting at the ejection port of the vent burner 23, there was a problem that the pulverized coal dropped to the bottom of the furnace and reduced the combustion rate without reaching the pulverized coal flame 13 especially in the low load zone of the furnace 1.

An object of the present invention is to solve the above-mentioned problems of the conventional technology, prevent the accumulation of pulverized coal in a branch pipe for responding to boiler load fluctuations such as a vent pipe, and prevent the pulverized coal from being ejected from the branch pipe. It is an object of the present invention to provide a pulverized coal combustion apparatus capable of completely burning everything over the boiler load range to improve fuel efficiency and improve the safety of the furnace.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention is a system from a pulverized coal manufacturing apparatus to a pulverized coal burner, in which a pulverized coal is supplied in the middle of a fuel supply system made of pulverized coal conveyed by primary air according to load fluctuation. C / in fuel supplied to charcoal burner side
A separating means such as a cyclone separator for separating a predetermined amount of primary air from the fuel supplied to the pulverized coal burner nozzle for adjusting A, and a primary air containing pulverized coal separated from the separating means. A branch passage for transporting and ejecting this primary air to the furnace side, and to the furnace outlet side of the passage so that pulverized coal can be maintained in the middle of the branch passage without accumulating pulverized coal. And a means such as an ejector for introducing gas.

[Action]

The C / A of the fuel supplied to the pulverized coal burner side is adjusted according to the load fluctuation of the combustion device such as the boiler in the middle of the fuel supply system from the pulverized coal manufacturing device to the pulverized coal burner, and the branch pipe such as the vent pipe is adjusted. The remaining primary air (vented air) containing a small amount of pulverized coal is introduced into the tube. By introducing the gas so that the flow state of the pulverized coal can be maintained in the middle of the vent air pipeline, the accumulation of the pulverized coal in the branch pipe such as the vent pipe is prevented, and the hitching at the ejection port is prevented.

Example of Invention

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is an enlarged view of a main part of FIG.

In this pulverized coal combustion apparatus, a wind box 2 is partitioned by a wind box partition 24 facing the furnace 1, and the pulverized coal burner nozzle 5 is arranged in the wind box 24. A venturi 6 is provided on the inner surface of the pulverized coal burner nozzle 5 located on the outer wall surface of the furnace.
The pulverized coal burner nozzle 5 in which is formed is connected to a pulverized coal supply pipe 15 from a pulverized coal production apparatus (not shown) via a cyclone separator 19.

Inside the cyclone separator 19 and the pulverized coal burner nozzle 5, a start back amplifier oil burner 11 is arranged concentrically with each other, and outside the start back amplifier oil burner 11 arranged inside the cyclone separator 19. Has a sleeve 22 arranged concentrically with the oil amplifier 11 for the back amplifier for starting.

One end of the sleeve 22 is arranged at a predetermined distance from the venturi 6, and a vent amount control damper 21 is installed near the other end of the sleeve 22 and connected to the vent pipe 20. The tip of the vent pipe 20 communicates with a vent burner 23 via an ejector 25. The vent burner 25 is arranged horizontally from the communicating portion with the vent pipe 20 in the same manner as the pulverized coal burner nozzle 5, and in the middle thereof is inclined toward the burner throat 12 side at an angle indicated by θ in the figure.

The ejector 25 is a vent pipe 20 as shown in detail in FIG.
One end of the cylindrical vent burner 23 is arranged in a state where a predetermined gap is formed with the outer peripheral surface of the vent pipe 20 at the tip of the
The inner diameter of the vent burner 23 is enlarged toward the furnace 1. Further, a sleeve 27 is arranged on the outer peripheral surface of the vent pipe 20 concentrically with the vent pipe 20, and an annular ejector air volume control damper 26 is arranged in the sleeve 27. The ejector air volume control damper 26 is an operation member.
By moving 28 in the direction of the arrow in the figure, the outer peripheral surface of the sleeve 27 slides, and the ejector air volume control damper 26
The gap between the vent burner 23 and one end of the vent burner 23 can be adjusted.

In FIG. 1, 14 is a flame holding ring, 16 is a secondary air swirl vane, 17 is a tertiary air register, and 18 is a secondary air register.

Next, the operation of the pulverized coal combustion device configured as described above will be described.

When starting a boiler, etc.
11 is ignited and a spark is formed. Next, pulverized coal burner 5
The pulverized coal produced by a pulverized coal production device (not shown) is introduced into the primary air via the pulverized coal supply pipe 15. The pulverized coal conveyed by the primary air enters the cyclone separator 19. The pulverized coal conveyed by the primary air in the cyclone separator 19 swirls along the outer peripheral surface of the cyclone separator 19, and a part of the primary air and a small amount of the pulverized coal reach the vent pipe 20 through the sleeve 22. The remaining primary air and the remaining pulverized coal are ejected from the pulverized coal burner nozzle 5 into the furnace.

Vent amount control damper against load fluctuation of boiler etc.
It can be handled by adjusting the opening of 21. That is,
When the load is low, increase the opening of the vent amount control damper 21,
By increasing the amount of primary air flowing from the sleeve 22 to the vent pipe 20 side, the C / A of the fuel ejected from the pulverized coal burner nozzle 5 is increased (it is assumed that the pulverized coal has a high concentration). In this case, the flow velocity of vent air flowing from the sleeve 22 through the vent pipe 20 is reduced.

Therefore, when the operating member 28 shown in FIG. 2 is moved to the outside of the furnace, the gap in the ejector 25 becomes large. For this reason, the air in the wind box 2 is sucked into the vent burner 23 through the ejector 25, and the vent pipe 20 and the vent burner 32 can be secured at a floating speed of pulverized coal or higher even under a low load operation, and the pulverized coal is pulverized. It can be prevented from accumulating in the road.

Further, the flow path of the vent air 9 is at the time of cutting the coal supply,
When the wind box 2 is pressurized, it becomes a negative pressure state due to the effect of the ejector 25, and when it becomes lower than the furnace pressure, the gas inside the passage flows backward into the pulverized coal burner nozzle 5 and the flame holding ring.
14 and the tip of the pulverized coal burner nozzle 5 may be burnt out. In this case, the ejector air volume control damper 26 is remotely controlled to be turned on and off, so that the gap of the ejector 25 can be appropriately adjusted so that the above situation does not occur.

Further, the primary air containing pulverized coal from the vent burner 23 is ejected in a state of being inclined toward the flame forming region side with respect to the furnace wall surface. Bent air flow velocity can be secured as high as the burner throat flow velocity by blowing air from the ejector 25, and the penetrating force from the vent burner 23 can penetrate the vent air into the coal flame, so that the pulverized coal in the vent air is It can be incinerated even when the boiler has a low load.

Generally, in view of the combustibility of pulverized coal, it is desirable that C / A is within a predetermined range, but the higher the C / A, the lower the transportability of pulverized coal.

In the above-mentioned embodiment, the cyclone separator 19 is provided in the wind box 2 in the vicinity of the pulverized coal burner nozzle 5, and therefore the fuel of high concentration (high C / A) is provided.
Since the distance from the pulverized coal burner nozzle 5 to the injection into the furnace can be shortened, the flashback phenomenon in the pulverized coal burner nozzle 5 can be prevented in advance.

Next, an example of the arrangement state of the vent burner 23 is shown in FIGS. In FIG. 3, two vent burners 23 are arranged, the ejection ports of the two vent burners 23 are each formed in a circular shape, and they are arranged on the upper side of the burner throat 23.

In FIG. 4, four vent burners 23 are provided and
Each of the two vent burners 23 has its ejection port formed in a circular shape, and is arranged on the outer peripheral side of the burner throat 23 at equal intervals.

In FIG. 5, four vent burners 23 are provided and
Each of the two vent burners 23 has an ejection port formed in an elliptical shape, and is arranged on the outer peripheral side of the burner throat 23 at equal intervals.

In each of the vent burners 23 shown in FIGS. 3 to 5, the jet port of the vent burner 23 is arranged so that the vent air has the same swirling direction as that of the combustion air.

With such a configuration, the flow of the vent air from the vent burner 23 is less likely to hinder the swirling of the combustion air, and the combustion characteristics (generation of NOx and unburned components) of the main burner may be deteriorated. Absent.

The present invention is not limited to the above embodiment,
Various modifications are possible.

For example, the gas introduced from the ejector 25 to the vent burner 23 side is not limited to the combustion air in the wind box 2, but circulates a part of the compressed air or the combustion exhaust gas of the boiler.
The combustion exhaust gas can also be used. Here, when the load of the boiler is low, the C / A in the fuel ejected from the pulverized coal burner nozzle 5 is adjusted to be high, and therefore,
The amount of primary air ejected from the vent burner 23 increases,
This vent air penetrates into the coal flame. Vent pipe 20
When using the combustion exhaust gas of the boiler as the gas to be introduced into, the combustion exhaust gas is originally in a state of insufficient oxygen amount, so the amount of oxygen blown into the coal flame can be adjusted, and the balance of the furnace bottom can be appropriately maintained. .

In the case of the compressed air and combustion exhaust gas mentioned above, a vent pipe
Insert a compressed air or combustion exhaust gas supply pipe in the middle of 20,
The ejection port may be arranged on the vent burner 23 side. Further, inside the wind box 2 or outside the wind box 2, a compressed air or combustion exhaust gas supply section is partitioned so as to surround an ejector installed in the vent pipe 20, and compressed air or combustion exhaust gas is introduced into this partition section. You may do it.

Further, in a large-sized boiler, about 10 burners are arranged side by side, arranged vertically in about 4 stages, and provided on the front wall and the rear wall of the can, respectively. Therefore, if the above-mentioned gas introducing means is installed in the vent pipe connected to each fine burner, the structure becomes extremely complicated. Therefore, a simple structure can be obtained by joining the vent pipes 20 from several pulverized coal burner nozzles 5 and providing the above-mentioned gas introduction means in the middle of the joined vent pipes 20.

〔The invention's effect〕

As described above, according to the present invention, the vent air amount can be controlled even when the load of the combustion device such as the boiler is low, and the C / A of the fuel introduced into the pulverized coal burner can be safely maintained, thus shortening the ignition time. As a result, flame holding can be secured, and the accumulation of pulverized coal contained in the vent air at a low concentration in the vent pipe and the hunting at the vent burner jet outlet can be prevented.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG.
FIG. 3 is an enlarged view of an essential part of the drawing, FIG. 3, FIG. 4 and FIG. 5 are explanatory views showing an arrangement state of a vent burner in the present invention, and FIG. 6 is a sectional view showing an example of a conventional pulverized coal combustion apparatus. . 1 ... Furnace, 2 ... Windbox, 5 ... Pulverized coal burner nozzle, 6 ... Venturi, 9 ... Vent air,
10 …… Pulverized coal, 11 …… Backup oil burner for startup,
12 …… Burner throat, 14 …… Flame holding ring, 15 …… Pulverized coal supply pipe, 19 …… Cyclone separator, 20 …… Vent pipe, 21 …… Vent amount control damper, 22 …… Sleeve, 23…
… Vent burner, 25 …… Ejector, 26 …… Ejector air flow adjustment damper, 27 …… Sleeve, 28 …… Operating member.

Claims (3)

(57) [Claims] 1. A system from a pulverized coal manufacturing apparatus to a pulverized coal burner, which is supplied to the pulverized coal burner side in the middle of a fuel supply system consisting of pulverized coal conveyed by primary air in response to load fluctuations. Separating means for separating a predetermined amount of primary air from the fuel supplied to the pulverized coal burner nozzle to adjust C / A in the fuel, and a primary means containing the pulverized coal separated from the separating means. A branch passage for conveying air and ejecting this primary air to the furnace side, and a furnace outlet side of the passage so that the pulverized coal can be maintained in the middle of the branch passage without accumulating pulverized coal. And a means for introducing gas to the pulverized coal combustion apparatus. 2. The pulverized coal combustion apparatus according to claim 1, wherein the means for introducing the gas comprises an ejector installed in the middle of a branch passage located in the wind box. . 3. The pulverized coal combustion apparatus according to claim 1, wherein the separating means is a cyclone separator adjacent to the wind box outside the wind box.