JPH0769042B2 - Pulverized coal combustion equipment - Google Patents

Description

The present invention relates to a pulverized coal combustion apparatus, and more particularly to a combustion apparatus capable of directly igniting pulverized coal.

[Conventional technology]

In recent years, the demand for pulverized coal-fired boilers has been rapidly increasing due to soaring oil fuels. However, since pulverized coal does not have a good ignitability, light oil, heavy oil, etc., which have a good ignitability, are generally used as auxiliary fuels.
Heavy oil is used as the fuel for the starter burner and light oil is used as the fuel for the ignition burner.

A conventional apparatus will be described based on the configuration of the burner portion of the pulverized coal combustion apparatus of FIG. 6 and the boiler system diagram of FIG. 7.

The burner part is a pulverized coal burner 23 which is a main burner, and a heavy oil starting burner 24 having a relatively small diameter which has the same tip opening as the opening tip surface of the pulverized coal burner 23 which is inserted into the center of the pulverized coal burner 23. The pulverized coal burner 23 comprises a small diameter light oil ignition burner 25 arranged near the outer periphery of the opening, and a flame stabilizer 37 attached to the outer periphery of the opening of the burner portion.

The boiler system is an air heater having a pulverized coal boiler 26 incorporating the burner device and a heat exchanger using exhaust gas.
27, a mill 28 for drying and crushing coal, a bunker 29 for storing coal and supplying coal to the mill 28, a heavy oil tank 30 for supplying heavy oil and light oil into the boil 26, and a light oil tank 31. .

In such a pulverized coal combustion apparatus, the operation at the time of start-up and load fluctuation will be described. First, light oil is supplied to the light oil ignition burner 25 in the boiler 26, and ignition is carried out by an igniter incorporated therein. The flame of the light oil ignition burner 25 ignites the heavy oil supplied to the heavy oil ignition burner 24 to increase the load to about 50%. The temperature in the furnace rises and the exhaust gas temperature rises,
When the air heater 27 can obtain dry air of 200 to 250 [° C.], this air is supplied to the mill 28, and the coal supplied from the bunker 29 is pulverized and dried in the mill 28. The pulverized pulverized coal is pulverized coal burner 23 of boiler 26
It is supplied with the primary air and is ignited by the flame of the heavy oil ignition burner 24 in the furnace which is already at a high temperature.

[Problems to be solved by the invention]

However, in the above device, when igniting pulverized coal with poor ignitability, light oil and heavy oil are used, and the temperature in the furnace is sufficiently raised by combustion of these light oil and heavy oil before igniting pulverized coal. Since it has to be kept, a considerable amount of light oil and heavy oil is required, and the operating cost and maintenance cost are not necessarily low. Furthermore, in addition to the pulverized coal, which is the main fuel, a storage facility for light oil and heavy oil is required, and the system scale will increase.

Therefore, recently, a combustion device that directly ignites pulverized coal by using plasma arc etc. without using ignition auxiliary fuel such as light oil or heavy oil has been developed, but when igniting by plasma arc, about 60-80 [Kw] 15 due to the mighty energy of
A high temperature atmosphere of 00 to 2000 [° C.] is required, and when such a high temperature environment is formed in the furnace, a large amount of thermal NOx is discharged, which causes another problem of being unfavorable for environmental hygiene.

Further, since the ignition torch by the plasma arc is arranged in the vicinity of the opening of the pulverized coal burner, it is worn by the collision of the pulverized coal, and if it is repeatedly used, the desired high voltage cannot be obtained and the ignition performance deteriorates. There are also drawbacks.

The present invention has been made in view of the above problems, and includes light oil,
Without using auxiliary ignition fuel such as heavy oil, a large amount of NO
It is an object of the present invention to provide a highly reliable pulverized coal combustion device capable of reliably igniting without discharging x.

[Means for solving problems]

To achieve the above object, the present invention is characterized in that at least a part of the flame stabilizer in contact with fuel is formed by a heat generating plate for ignition. Is directly and continuously applied to pulverized coal to enable ignition. For example, a ceramic heater is used as the heating plate, and the pulverized coal is
Reliable ignition at 1000 to 1100 ° C. At this time, a large amount of NOx as in the case of using a plasma arc is not generated. Further, since the ceramic heater is excellent in wear resistance and wear resistance, the ignition performance is stable, and it also functions sufficiently as a flame stabilizer itself.

〔Example〕

FIG. 1 is a sectional view of an essential part of an ignition burner in an embodiment, in which a primary sleeve 1 through which pulverized coal 4 and primary air 5 for supplying pulverized coal is passed has a tub-shaped flame stabilizer 2 fixed to its open end. A heat generating plate 3 is attached to the inner edge of the flame stabilizer 2 so as to partially project inward.

2 (a) and 2 (b) are a front view and a side sectional view of the heat generating plate.

The heat generating plate 3 has a ring shape as a whole, and is composed of an outer peripheral ring 7 made of an insulating ceramic such as AlN, and a heater 6 integrally formed inside the outer peripheral ring 7 and made of a ZrB ₂ / SiC-based conductive ceramic. To be done. The inner edge shape of the heat generating plate 3 has projections 3a having a predetermined width at approximately equal intervals, and the projections 3a allow the heater 6 to sufficiently contact the pulverized coal and are shown by an arrow A in FIG. As described above, the low speed region of the air-fuel mixture of pulverized coal and air required for ignition and flame holding is formed around the heater 6.

In manufacturing the heat generating plate 3, first, the ring member having the projection 3a as the inner diameter and the step portion having the bent peripheral wall shown in FIG. 2 (a) is previously formed on one side surface of the inner edge is insulated. A green sheet of conductive ceramic having a constant width along the peripheral wall is laminated on the stepped portion, and is hardened and integrated by a hot press. This integrated molded product is cut along the unevenness of the insulating ceramics into a shape shown in FIG. 2 (a) by a laser cutting machine.

The arrow B in FIG. 1 indicates the inflow of the secondary air 35 supplied from the outside of the primary sleeve 1, and the reference numeral 32 in FIG.

In the above burner, the flow rate of pulverized coal near the heat generating plate 3 is 15 to 20 [m / s] and collides with the heat generating plate 3,
Moreover, although the temperature rises to around 1000 [° C] due to the radiant heat of the flame and the like, the AlN and ZrB ₂ / SiC ceramics have excellent wear resistance and wear resistance, so they do not affect the ignition performance.

FIG. 4 is a control block diagram of the heat generation plate 3 of FIG. 3, in which the electrode 32 of the heater 6 of the heat generation plate 3 is connected to the power source 34,
The heater 6 is kept at a predetermined temperature by controlling the on / off of the controller 34 by the controller 33.

FIG. 4 is a structural diagram of a combustion apparatus equipped with the burner.

The burner part has a small-diameter first sleeve 8 located at the center thereof and a second sleeve 9 arranged outside the first sleeve 8.
And a third sleeve arranged further outside the second sleeve 9.
And a pulverized coal starter for igniting the open end of the third sleeve 10 to the pulverized coal main burner 11 which is the main combustion burner of the boiler, and the open end of the second sleeve 9 to the pulverized coal of the main burner 11. The open end of the burner 12 and the first sleeve 8 is used as a pulverized coal ignition burner 13 for igniting the starting burner 12. It goes without saying that a mixture of pulverized coal and air is supplied to all of these burners 11, 12, and 13.

Next, the ignition action of the burner will be described.

The pulverized coal 4 and the primary air 5 supplied at a flow rate of 15 to 20 [m / s] in the primary sleeve 8 collide with the heat generating plate 3, and the secondary air 35 from the secondary sleeve 9 is further absorbed by the flame stabilizer 2. Against which the circulating vortex region 36 is formed in the flame stabilizer 2. The flow velocity in this circulating vortex region is 0-5 [m / s] in absolute value.
Is a low speed, and is an optimal region for ignition and flame holding. A heating element plate 3 which has been heated to 1000 to 1200 [° C.] is located in this region, and when the pulverized coal particles from the ignition burner 13 collide with it, the volatile components in the pulverized coal are continuously ignited, A flame is formed in the circulating vortex area 36. This flame propagates successively to the pulverized coal supplied from the starter burner 12 on the outer side and the pulverized coal supplied from the main burner 11 on the outer side, and spreads to the pulverized coal in the entire furnace.

FIG. 5 shows a boiler system to which the present invention is applied.

The above pulverized coal burner is built in the boiler 14,
It is also possible to use it as a duct burner 20 for heating the primary air to the mill 16 as well as being used as the main fuel device of 14.

The coal stored in the coarse-grain bin 19 is pulverized into pulverized coal by the mill 16, and the primary air dried by the duct burner 20 is passed through the ignition start-up duct 21 and the main burner duct 22 to burner in the boiler 14. Sent to the device. In the burner device, as described above, the pulverized coal ignition burner 13, the starting burner 12, and the main burner 11 are ignited in this order.

Direct ignition of pulverized coal in the ignition burner 13 is 200
It is possible if the particle size of the pulverized coal is about 80% pass of the mesh, but at the time of ignition and starting, the coal is preliminarily classified.
According to 17, the coarse grain bottle 19 and the fine grain bottle 18 are separately stored and stored, and the ultra fine coal of 400 mesh 80% pass selected by the fine grain bottle 18 is directly ignited to the ignition starting duct 21. By supplying, it is possible to prevent discharge of unburned pulverized coal. After starting, load is reduced by pulverized coal starting burner 12.
After raising the temperature in the furnace sufficiently to about 50%, the main burner 11 is ignited by the pulverized coal from the mill 16. When the outlet air temperature of the air heater 15 becomes high, the duct burner 20 is squeezed and returned to the normal line.

〔The invention's effect〕

The present invention is as described above, and the pulverized coal is directly ignited by the heat generating plate provided in the flame stabilizer.
Therefore, it is possible to ignite reliably without requiring auxiliary fuel such as light oil or heavy oil, and to significantly reduce the cost of the combustion device. Further, it is possible to make the device highly reliable for a long period of time as compared with an ignition means such as a plasma arc.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of the present invention, FIG. 2 shows a heating plate used in the present invention, (a) is a front view, (b) is a side sectional view, and FIG. 3 is a heating plate control block diagram. , 4th
FIG. 5 is a structural diagram of a burner apparatus according to an embodiment of the present invention, FIG. 5 is a control block diagram of a boiler system using the present invention, FIG. 6 is a structural diagram of a conventional burner apparatus, and FIG. 7 is a conventional boiler system. It is a control block diagram. 1 ... Primary sleeve, 2 ... Flame stabilizer, 3 ... Heating plate, 4 ... Pulverized coal, 5 ... Primary air, 6 ... Heater, 7
…… Outer ring.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryuichi Sugita 3 36 Takaracho, Kure City, Hiroshima Prefecture Babkotsu Hitachi Co., Ltd. Kure Research Institute (72) Akira Baba 3 36 36 Takaracho, Kure City, Hiroshima Prefecture Babkotsu Hitachi Co., Ltd. Kure Research Institute (56) Reference JP 61-11514 (JP, A) JP 61-272512 (JP, A)

Claims (2)

[Claims] 1. A pulverized coal combustor in which a flame stabilizer is provided at the tip of a primary sleeve for supplying a mixture of pulverized coal and air, and at least a part of the pulverized coal combustion device which comes into contact with fuel in the flame stabilizer is used for ignition. A pulverized coal combustion device characterized by being formed by a heating plate. 2. The pulverized coal combustion apparatus according to claim 1, wherein the heating plate is made of a ceramic material.