JPH0547928Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a coal combustion device, and more specifically, it uses pulverized coal as the main fuel and can achieve high combustion efficiency equivalent to a combustion furnace using pulverized coal. This article relates to a coal combustion furnace that is small and has a simple structure.

This type of coal combustion furnace has a heat converter in the flame spout,
The high heat of the flame and hot air ejected from the flame outlet is directly utilized by connecting other equipment that requires heating, such as a boiler and a humidifier.

[Conventional technology]

A pulverized coal combustion furnace using pulverized coal obtained by pulverizing coal is known. Pulverized coal combustion furnace reduces the particle size of coal.
It is atomized to about 0.05 mm, mixed with primary air, injected into the combustion chamber from an injection burner, brought into contact with secondary air and tertiary air, and combusted. Since the contact surface area between coal and air is more than 800 times larger than that of lump coal, combustion efficiency is high and high-temperature combustion gas can be obtained.

However, the combustion furnace is relatively large and is not suitable for downsizing. There are many parts of the machine that wear out, and equipment and maintenance costs are high. Furthermore, a large number of auxiliary equipment is required to atomize coal to a particle size of 0.05 mm, making it impractical as a coal combustion furnace.

In other words, powdered coal (coal with a grain size of about 5 mm to 50 mm and low processing costs) is suitable for a somewhat practical coal combustion furnace.
There are two types: fluidized bed combustion furnaces (particle size of about 5 mm) and grate combustion furnaces (particle size of about 50 mm).

A fluidized bed combustion furnace is one in which air is blown at high speed through a dispersion plate from below the coal particles, and the fluidized bed formed by this, which has a high stirring and fluidizing effect, is combusted. The injected air serves both as coal flow and as combustion air.

Fluidized bed combustion furnaces have combustion efficiency that is second only to pulverized coal combustion furnaces because the combustion coal is constantly moving and easy to burn. However, due to its structure, pressure loss is large and the required power is large. It is also necessary to make the particle size of the coal the same. Since the combustion air is also used for the rotational movement of the coal, there is a drawback that excess air is produced, and the air-fuel ratio cannot be selected to the optimum value. Furthermore, since the ash is scattered by the high velocity of the supplied air, a special dust extraction device is required, which poses many practical problems.

On the other hand, the grate combustion furnace is a practical device that has a proven track record as a device that uses powdered coal, which is inexpensive to process. The pulverized coal is distributed almost evenly on the grate using a stoker or the like, and air is supplied from below to burn the pulverized coal on the grate. Make the grate slanted or movable to increase combustion efficiency. The ash produced by the combustion falls down through the grate and is discharged.

[Problem that the invention attempts to solve]

However, grate combustion furnaces have the following drawbacks.

When powdered coal supplied onto a grate is burned while supplying air from below, impurities such as lime and iron contained in the coal are dissolved and clinker is generated. This solidifies and adheres to the grate, clogging the ventilation openings of the grate, and reducing the combustion efficiency of pulverized coal during long-term operation. For this reason, a clinker removal device has been proposed, but the structure is complicated and there is no perfect device.

Stable combustion cannot be achieved unless a uniform layer of pulverized coal is formed at all times, so the area of the fire bed must be expanded, and the entire combustion furnace becomes large.

In order to simplify the structure, the stoker for evenly distributing the pulverized coal and the grate with the complicated structure described above are omitted and the pulverized coal is fed from above to a stationary grate, so that the pulverized coal is deposited in a substantially conical shape. The combustion rate is slow in the thicker and thinner parts of the deposited layer, and heat is trapped in the thicker part of the deposited layer, promoting the generation of clinker, making it impossible to achieve complete combustion as a whole.

Since each piece of pulverized coal is burned in a stationary state, if there is pulverized coal with a relatively large particle size, it will be difficult for the flame to spread to surfaces other than the bottom, making it impossible to achieve a uniform combustion rate.

The purpose of the present invention is to provide a small-sized and simple-structured pulverized coal combustion furnace based on a grate combustion furnace and adding the advantages of a fluidized bed combustion furnace.

Another object of the present invention is to provide a pulverized coal combustion furnace that eliminates the above-mentioned drawbacks of conventional combustion furnaces.

[Means for solving problems]

The above purpose is to have a combustion chamber consisting of an upper and a lower chamber, a pulverized coal supply port is provided in the ceiling of the upper chamber to allow the pulverized coal to fall naturally, and a plurality of secondary air introduction holes are provided almost all around the peripheral wall. Further, a flame outlet is formed in a part of the peripheral wall, a fire bed with a flat top surface is provided at the bottom of the lower chamber, and a plurality of primary air introduction holes are provided in the fire bed in a substantially vertical shape. It is a vertical pulverized coal combustion furnace, which is equipped with a blower outside the combustion chamber that supplies combustion air into the combustion chamber through the primary and secondary air introduction holes, and A flat sliding plate that can closely slide along the upper surface of the opening of the air introduction hole, and the sliding plate is provided outside the combustion chamber and actively moves back and forth intermittently during combustion. The present invention is solved by a pulverized coal combustion furnace comprising a drive device for crushing clinker and a device for equalizing the thickness of the pulverized coal layer, which has a discharge port formed in a part of the peripheral wall of the lower chamber.

〔Example〕

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

The pulverized coal combustion furnace according to the present invention has a combustion chamber configured by an upper chamber 1 and a lower chamber 2 that are connected vertically. The upper chamber 1 is formed of an outer wall 3 made of iron plate and an inner wall 4 made of heat-resistant material, and a hollow part is provided between the two. A plurality of secondary air introduction holes 5 are perforated in the inner wall 4 to communicate the inside of the combustion chamber with the hollow portion.

The ceiling of the upper chamber 1 has one or more pulverized coal supply ports 6 for supplying pulverized coal in a natural manner into the combustion chamber.
will be provided. Feeding hopper 7 above the pulverized coal combustion furnace
The pulverized coal is sent to the pulverized coal supply port 6 via the screw conveyor 8. Further, another air introduction hole 9 is opened in the wall surface of the powdered coal supply port 6 facing the hollow portion of the upper chamber 1 mentioned above.

Further, a flame spout 10 is provided which projects outward through the inner wall 4 and outer wall 3 of the upper chamber 1. This flame spout 10 is used for connection with other equipment to be heated.

The lower chamber 2 has a hollow portion 11 therebetween and is configured in a sealed manner with inner and outer walls 12 and 13 made of iron plates. A heat-resistant material 14 is laid on the inner wall 12 at the bottom of the lower chamber 2 to constitute a fire bed, and the heat-resistant material 14 and the corresponding outer wall 1
3, a plurality of small diameter pipes are arranged substantially vertically to form a plurality of primary air introduction ports 15. Although the upper surface of the refractory material 14 is slightly inclined in the embodiment shown in FIG. 1, it can also be made horizontal. In addition, the primary air introduction hole 15 is located inside the combustion chamber as shown in Fig. 3.
6φ, and 12φ outside the combustion chamber.
Further, water is circulated from a water tank 16 into the hollow part 11 to cool the inner and outer walls made of iron plates.

A blower 26 is provided outside the combustion chamber and sends combustion air to the secondary air introduction hole 5 and the primary air introduction hole 15 via conduits 17A and 17B.

The main features of this invention are the removal of clinker produced on the fire bed by pulverized coal combustion, the crushing of clinker and the thickness of the pulverized coal layer to improve combustion efficiency by stirring the pulverized coal on the fire bed and improving air circulation. This device includes a sliding plate 18 made of mild steel that can closely slide along the upper surface of the opening of the primary air inlet of the fire bed, and a a drive device 19 that is installed in the holder and actively moves the sliding plate 18 back and forth intermittently over the entire surface area of the fire bed; and an outlet 20 that is formed through the inner and outer walls 12 and 13 of the lower chamber 2. Equipped with.

As shown in FIGS. 4A and 4B, the sliding plate 18 has a thickness of 9 to 15 mm and has an inclined forward end.
A recess 21 is formed at the tip of the mild steel plate. The purpose of this shape is to make it easier to crush relatively large-diameter clinker while damming it up when the sliding plate moves, and to reduce crushing resistance.

In this embodiment, a hydraulic cylinder is used as the drive device 19, but a rack and pinion may also be used and driven by an electric motor. Further, although the sliding plate 18 has a slope and a recessed portion at its tip, it can be formed into any desired shape, such as tilting backwards or vertically, or forming the recessed portion into a protrusion or a straight line.

According to the pulverized coal combustion furnace of the present invention, the primary air introduction hole 1
Since the pore size of No. 5 is relatively small, almost no ash produced by combustion falls out. Therefore, the ash together with the clinker crushed by the sliding plate 18 is pushed out through the discharge port 20 by the sliding plate 18. The extruded clinker and ash pass through water once and are discharged to the outside from the discharge port 23 via the inclined screw conveyor 22. Therefore, effective combustion gas within the combustion chamber does not leak to the outside. 24 is a sister tank provided for this purpose.

Next, the operation of the present invention will be explained.

The screw conveyor 8 is driven to send the powdered coal in the hopper 7 to the supply port 6, allowing it to naturally fall and deposit it in a conical shape on the fire bed. The pulverized coal is ignited by a igniter such as a kerosene burner (not shown), and at the same time, the blower 26 is activated.

Although the primary combustion of the pulverized coal in the lower chamber 2 is carried out using only the primary air, it is still insufficient and smoke is generated. When the secondary air is further supplied to the center of the combustion furnace to overcome the rising combustion gas in the upper chamber 1, the combustion gas generated in the lower chamber 2 is completely burned (secondary combustion) and becomes a flame (tertiary combustion). It is then sent to another device (not shown) that requires heating. At this time, the air sent into the combustion chamber from the air introduction hole 9 acts as an air curtain to prevent flames from entering the screw conveyor 8.

As combustion of the pulverized coal progresses, clinker is generated in the lower layer, ie, the pulverized coal layer near the fire bed, and adheres to the surface of the fire bed. Furthermore, as described above, since the diameter of the primary air introduction hole 15 is small, the ash does not fall below the fire bed, but instead accumulates in the lower layer of the pulverized coal. At predetermined intervals, the driving device 19 pushes the sliding plate 18 to the left in FIG. 1 to crush the clinker formed in the lower layer.
The clinker and ash pass through the discharge port 20 and are discharged to the outside from the discharge port 23 via the inclined screw conveyor 22. After discharging, the sliding plate 18 can be immediately retreated and retracted. This reciprocating movement of the sliding plate 18 equalizes the thickness of the powdered coal layer deposited in a conical shape on the fire bed.

In order to automate the above-mentioned operations, the present invention is equipped with a control device 25 to control the operations of the screw conveyors 8, 22, the blower 26, and the crushing and equalizing device. Further, if the temperature of the equipment to be heated, such as a boiler, becomes higher than a predetermined temperature, the operation of each of the above devices is stopped or reduced, and if the temperature becomes lower than the predetermined temperature, the operation is restored.

[Effect of idea]

The present invention is constructed as described above, and the clinker is removed by the forward movement of the sliding plate, and the air introduction hole of the fire bed is not clogged with clinker, so it can be operated for a long time. high combustion efficiency is maintained. Further, the thickness of the powdered coal layer deposited on the fire bed is equalized by the reciprocating movement of the sliding plate, so that complete combustion can be achieved. Since the crushing and equalization device that performs these operations is a small device, it is useful for downsizing pulverized coal combustion furnaces. Also, since the grate structure has multiple small holes similar to those in a fluidized bed combustion furnace, the wind pressure is strong and the combustion speed is fast. Furthermore, since the pulverized coal is intermittently rolled by the crushing and equalizing device, substantially the same effect as in the case of using a movable grate in a conventional combustion furnace can be obtained.
Furthermore, since the ash is discharged together with the clinker without falling below the fire bed, it has many advantages such as eliminating the trouble of cleaning the ash.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway sectional view of the pulverized coal combustion furnace of the present invention, Fig. 2 is a side view of Fig. 1, Fig. 3 is a sectional view showing a part of the grate, Figs. Figure 4B is a side view and a plan view of the sliding plate. 1... Upper chamber, 2... Lower chamber, 5... Secondary air introduction hole, 6... Powdered coal supply port, 10... Flame spout, 15... Primary air introduction hole, 16... Water tank, 18...Sliding plate, 19...Drive device, 20...
...Exhaust port, 26...Blower.

Claims (1)

[Scope of utility model registration request] It has a combustion chamber consisting of upper and lower chambers 1 and 2, and the ceiling of the upper chamber 1 is provided with a pulverized coal supply port 6 through which pulverized coal naturally falls, and a plurality of secondary air introduction holes 5 are provided almost all around the circumferential wall. However, there is also a flame spout 1 in a part of the peripheral wall.
0 is formed, and a fire bed with a flat upper surface is provided at the bottom of the lower chamber 2, and a plurality of primary air introduction holes 15 are formed in the fire bed in a substantially vertical shape, and the fire bed has a plurality of primary air introduction holes 15 formed in a substantially vertical shape. is a blower 26 that supplies combustion air into the combustion chamber through the primary and secondary air introduction holes 5 and 15;
A vertical pulverized coal combustion furnace comprising: a flat sliding plate 18 that can closely slide along the upper surface of the opening of the primary air introduction hole 15 of the fire bed; A clinker crushing and powdering apparatus having a drive device 19 which is installed in the combustion chamber and actively reciprocates the sliding plate intermittently during combustion, and a discharge port 20 formed in a part of the peripheral wall of the lower chamber 2. A pulverized coal combustion furnace equipped with a device to equalize the thickness of the coal seam.