JP3115687B2 - Coal crusher and water injection control method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coal crusher, and more particularly to a coal crusher and a coal crusher capable of preventing a blockage trouble at the time of coal supply to a coal crusher and enabling a smooth operation of a plant. And a method for controlling the amount of injected water.

[0002]

2. Description of the Related Art There are boilers which use powdered coal (hereinafter, referred to as pulverized coal) as a fuel, such as a large boiler for thermal power generation and a boiler for general industry, which are obtained by pulverizing coal. FIG.
In the drawings, there is shown a conventional apparatus for pulverizing coal, a coal pulverization apparatus called a vertical ball mill. The pulverized coal C falls in the coal feed pipe 8 of the pulverizing apparatus main body 1 and reaches the pulverizing section.
The crushing unit includes an upper fixed wheel 6 to which a pressing force is applied by a pressing device 4 and a lower rolling wheel 9 which is rotated by a driving device 15.
And a plurality of crushing balls 7 arranged between the upper fixed wheel 6 and the lower wheel 9 and rolling with the rotation of the lower wheel 9.
And formed from The coal reaching the pulverizing section is moved to the position of the pulverizing ball 7 by the centrifugal force generated by the rotation of the lower rolling wheel 9 and pulverized. The pulverized coal rises in the pulverizer main body 1 by air supplied from the air port 17 (usually, high-temperature air is also used for drying the coal). The air stream containing the pulverized coal is turned into a swirling air stream by the swirling blades 12 installed at the entrance of the classifier 11, and the large-diameter particles fall down in the classifier 11 and fall into the pulverizing section to be re-pulverized. The charcoal flows into the pulverized coal pipe 13 together with the airflow, and is conveyed to the pulverized coal burner (not shown) by the airflow.

[Problems to be solved by the invention]

[0003] In the pulverizing apparatus having the above-mentioned structure, several incidents of coal adhesion have been reported mainly in the lower part of the coal feed pipe 8, and the clogging accident of the coal feed pipe 8 is usually caused by the following causes. That is, coal contains mineral matter (usually called ash) in addition to combustible coal,
Low-grade coal called sludge coal discharged in the process of coal preparation contains a lot of ash. Furthermore, the sludge coal ash contains many cases containing a large amount of clay such as kaolinite or muscovite. As is well known, clay has a property of firmly fixing and solidifying when dried in a state of being moistened with water, so that coal containing a clay also has this property.

[0004] Usually, most of these sludge coals are disposed of as coal mine waste. However, a part of the sludge may be mixed with high quality coal (high calorie coal) for calorie control. Even if it is not coal mixed with sludge charcoal, there are relatively many coals that contain clay as soil of coal fields. As described above, since the clay component has a property of firmly fixing and solidifying when dried in a state of being moistened with water, the coal containing the clay component also has this property.

[0005] Coal is usually wet in a crushing apparatus main body 1 in a wet state.
The coal is dried by hot air at the lower part of the coal feed pipe 8, but if the ash of this coal contains clay, it dries on the lower inner wall of the coal feed pipe 8 and the clay adheres. The adhesion layer gradually grows, and eventually leads to a situation in which the coal feed pipe 8 is blocked or unusable.

As a means for solving these problems,
A device has been proposed in which a scraping blade is attached to the lower rolling wheel 9 to scrape the inner wall of the coal feed pipe 8 by using the rotation of the lower rolling wheel, or to perform a scraping operation by using another power source. I have. However, these devices have not been able to provide a sufficient effect because coal, particularly clay, adheres to the scraping blade itself.

As another means, instead of scraping off the coal layer that has adhered, water is allowed to flow in advance on the inner wall of the coal feed pipe 8 through the water injection pipe 2 and the water injection hole 3, and the clay content is also formed below the coal feed pipe 8. Has been proposed to prevent drying and solidification, which has been effective. However, while this method can prevent the adhesion and solidification of coal, supplying water to the pulverizer is an operation opposite to the drying of coal, so that the classification efficiency of the classifier 11 decreases, Problems such as a decrease in the flammability of charcoal occur.

[0008] Accordingly, an object of the present invention is to reduce the classification efficiency of the classifier when the amount of water for preventing blockage of the coal feed pipe is too large, the flammability of pulverized coal, and the like.
In order to solve the problems such as increase in heat loss of the boiler due to heat of water evaporation, it is possible to effectively prevent coal from adhering to the coal feed pipe, decrease coal classification efficiency, decrease pulverized coal flammability, etc. It is an object of the present invention to provide a coal pulverizing apparatus without the above and a method for controlling the water injection amount of the coal pulverizing apparatus.

[0009]

According to the present invention, a water injection pump and a water injection pump are provided above a coal feed pipe for supplying coal to a pulverizing section.
The water supplied through the water valve flows to the inner wall of the coal pipe.
Oite coal pulverizer provided with a water injection hole for Do, the tube wall temperature detector for detecting the wall temperature of the Kyusumikan provided, preset the tube wall temperature detection signal from the tube wall temperature detector opening of the injection valve based on the comparison result between the tube wall temperature setting signal
A coal crusher provided with a computing device for controlling the degree is provided.

[0010] Further, according to the present invention, the water injection rate control method for stone <br/> coal pulverizing apparatus which performs injection of coal antiadhesive coal on the inner wall surface of the supplied coal feed pipe to the grinding unit, the coal feed A method for controlling a water injection amount of a coal crusher, wherein the water injection amount is controlled based on a pipe wall temperature of the pipe is provided. In this case, the tube wall temperature
Temperature compared to the normal tube wall temperature.
Increase the amount of water and, if small, decrease the amount of water injected
You.

The pipe wall temperature detector may be arranged adjacent to the inner wall, outer wall or inner wall of the coal feed pipe, and whether or not water is flowing, whether or not fine coal powder adheres to the pipe wall. Is detected by monitoring the temperature, and the supply amount of the adhesion preventing supply water is controlled based on this.

[0012]

Although the temperature of water rises when heated, the temperature does not rise above a temperature determined by the pressure under a predetermined atmospheric pressure, and the heat added at this temperature is consumed as latent heat of evaporation of water. Is done. Due to the physical properties of this water, when the coal adhering to the inner wall of the coal feed pipe is wet, it does not rise above the temperature determined by the pressure. The present invention utilizes this to optimize the amount of anti-adhesion water and not only can minimize the amount of water injected into the crushing device to the minimum necessary, but also finds an abnormality in the water injection device at an early stage. be able to.

[0013]

FIG. 1 is a schematic view of a coal pulverizing apparatus according to an embodiment of the present invention. Parts corresponding to those of the prior art shown in FIG. 4 are designated by the same reference numerals. 2,
A water injection hole 3, a pressurizing device 4, a thermocouple 5, which is a tube wall temperature detector , an upper fixed wheel 6, a crushing ball 7, a coal feed tube 8, a lower rolling wheel 9, a classifier 11, a rotating blade 12, It includes a pulverized coal pipe 13, a driving device 15, a water injector 16, an air port 17, and further includes a computing device 10, a CRT screen 14, a valve 18 as a water injection valve, a water injection pump 19, a tube wall temperature detection signal 20, a tube wall temperature. The setting signal 21 is also shown.

Before describing FIG. 1, experimental data performed by the inventors will be described with reference to FIGS. FIG. 2 shows a case in which a thermocouple insertion hole is provided from the outside of the coal feed pipe as shown in FIG. The temperature was measured and shown as a temperature distribution in the longitudinal direction of the coal feed pipe,
When the fine powder in the coal feed is not attached to the inner wall of the coal feed pipe, the temperature of the pipe wall rises toward the lower part of the coal feed pipe.
0 ° C. or less.

On the other hand, if an adhesion layer of fine powder is formed on the inner wall of the coal feed pipe, water cannot flow directly on the surface of the adhesion layer, and thus cannot be directly cooled. As shown in FIG. 2 (b), the temperature at a position slightly (about 3 mm) away from is higher than 100 ° C. by the air supplied to the pulverizer. That is, by utilizing this fact, it becomes possible to measure the temperature of the pipe wall of the coal feed pipe to know the state of adhesion of the fine powder to the inner wall of the coal feed pipe, and the present invention utilizes this.

In FIG. 1, the coal C to be pulverized falls in the coal feed pipe 8 of the pulverizer main body 1 and reaches the pulverizing section. The pulverizing unit includes an upper fixed wheel 6 to which pressure is applied by the pressurizing device 4.
And the lower wheel 9 rotationally driven by the driving device 15
And a grinding ball 7 disposed between the upper fixed wheel 6 and the lower wheel 9 and rolling with the rotation of the lower wheel 9. The coal that has reached the pulverizing section is moved to the position of the pulverizing ball 7 by the centrifugal force generated by the rotation of the lower rolling wheel 9 and pulverized. The pulverized coal rises in the pulverizer main body 1 by air supplied from the air port 17 (usually, high-temperature air is also used for drying the coal). The air stream containing the pulverized coal is turned into a swirling air stream by the swirling blades 12 installed at the entrance of the classifier 11, and the large-diameter particles fall down in the classifier 11 to fall into the pulverizing section and are re-pulverized. The charcoal flows into the pulverized coal pipe 13 together with the airflow, and is conveyed by airflow to a pulverized coal burner (not shown).

Water for preventing the fine powder from adhering to the inner wall of the coal feed pipe 8 (hereinafter referred to as water for preventing adhesion) enters the water injector 16 through the water injection pipe 2 and flows through the water injection hole 3 into the coal feed pipe. 8 and flow down the inner wall. Arranged in the longitudinal direction of coal feed pipe 8
And a plurality of thermocouples 5 inserted inside the wall of the coal feed pipe 8.
To measure the wall temperature of the coal feed pipe 8. A thermocouple 5 is also arranged in the circumferential direction of the coal feed pipe 8, and the temperature distribution of the pipe wall in the circumferential direction is measured by the thermocouple 5 arranged in the circumferential direction. Monitor volume uniformity.

The tube wall temperature detection signal 20 detected by the thermocouple 5 is taken into the arithmetic unit 10 and displayed on the CRT screen 14 as a temperature distribution. The operator thus monitors the temperature distribution of this <br/>, by the arithmetic unit 10
The normal setting of the tube wall temperature setting signal 21
(Temperature pattern), and a calculation is performed to determine the maximum temperature difference from the normal temperature pattern. If the temperature difference is equal to or greater than a preset allowable value, a signal is generated from the arithmetic unit 10 (which can be operated by an operator) to open the water injection valve 18 to increase the water injection amount. Similarly, the temperature pattern in the circumferential direction is compared with the normal temperature pattern input in advance and calculated, and if the temperature difference is equal to or greater than a predetermined allowable value, an alarm is generated and the operation is performed. Watch out for members. An abnormality in the temperature pattern in the circumferential direction is caused by a decrease in the injection pressure and a clogging of the injection hole 3, that is, due to various other factors.

[0019]

As described above, according to the present invention, not only can the amount of water injected into the crushing device be minimized, but also an abnormality in the water injection device can be detected at an early stage.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a coal crusher according to the present invention.

FIG. 2 is a diagram showing an example of a temperature distribution of a coal feed pipe measured by the method according to the present invention.

FIG. 3 is a view showing attachment of a thermocouple arranged for measuring the temperature distribution shown in FIG. 2;

FIG. 4 is a diagram showing an example of a conventional coal crusher.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pulverizer main body 2 ... Injection pipe 3 ... Injection hole 4 ... Pressurizer 5 ... Thermocouple 6 ... Upper fixed wheel 7 ... Pulverizing ball 8 ... Coal supply pipe 9 ... Lower wheel 10 ... Computing device 11 ... Classifier 12 ... Swirl vane 13 ... Pulverized coal pipe 14 ... CRT screen 15 ... Driver 16 ... Water injector 17 ... Air port 18 ... Valve 19 ... Injection pump 20 ... Tube wall temperature detection signal 21 ... Tube wall temperature setting signal

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B02C 15/00-15/16

Claims (3)

(57) [Claims] 1. An upper part of a coal feed pipe for supplying coal to a pulverizing section,
Wherein the water injection is supplied via a water injection pump and injection valve
Oite coal pulverizer provided with a water injection hole for flow down the inner wall surface of the coal feed pipe, the tube wall temperature detector for detecting the wall temperature of the Kyusumikan provided, the tube wall from the tube wall temperature detector coal pulverizer characterized in that a computing device for controlling the opening of the water injection valve based on the comparison result between the tube wall temperature setting signal preset temperature detection signal. 2. An inner wall surface of a coal feed pipe for supplying coal to a pulverizing section.
Water injection amount control of the coal pulverizer for performing injection of coal antiadhesive
In the method, the water injection amount control method of the coal mill, characterized by controlling the water injection amount based on the wall temperature of the Kyusumikan. 3. The amount of water injected into the coal crusher according to claim 2.
In the control method, the tube wall temperature is compared with a normal tube wall temperature.
In comparison, when the size is large, the amount of water injection is increased.
Coal grinding characterized by reducing the amount of water injected
How to control the amount of water injected into the device.