JPH05269394A - Device for grinding coal and method for controlling rate of water injection - Google Patents

Abstract

PURPOSE:To automatically control the rate of water injection in order to solve nonconformity becoming such a state that the build-up layer of clay is gradually grown and then a coal feeding pipe is finally. blocked and is not used. CONSTITUTION:An injector 16 and water injecting holes 3 are provided in the upper part of a coal feeding pipe 8 for supplying coal to a grinding part. Thereby injected water flows down on the inner wall surface of the coal feeding pipe. Further a grinding device for grinding coal supplied from the coal feeding pipe is provided with a detector (thermocouple 5) for detecting the tube wall temperature of the coal feeding pipe and an arithmetic unit 10 which compares a tube wall temperature detection signal 20 outputted from the detector with a tube wall temperature setting signal 21. The rate of water injection supplied through the water injecting holes is increased and decreased on the basis of the comparison result of the tube wall temperature detection signal and the tube wall temperature setting signal.

Description

Detailed Description of the Invention

[0001]

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

[0002]

Boilers using powdered coal (hereinafter referred to as pulverized coal) obtained by pulverizing coal, such as large boilers for thermal power generation and boilers for general industries, as fuel There is. FIG. 4 shows a coal crushing device called a vertical ball mill as a conventional device for crushing coal. The crushed coal C falls in the coal feeding pipe 8 of the crusher body 1 and reaches the crushing section. The crushing unit is disposed between the upper fixed wheel 6 to which a pressing force is applied by the pressurizing device 4, the lower roller 9 that is rotated by the drive device 15, and the upper fixed wheel 6 and the lower roller 9, and the lower roller. It is formed of a plurality of grinding balls 7 that roll as the wheel 9 rotates.
The coal reaching the crushing section is moved to the position of the crushing ball 7 and crushed by the centrifugal force generated by the rotation of the lower roller 9. The crushed coal rises in the crusher main body 1 by the air supplied from the air port 17 (usually used as high-temperature air to also dry the coal). The air flow containing the crushed coal is swirling blade 1 installed at the inlet of the classifier 11.
A swirling air flow is generated by 2, and large-diameter particles descend in the classifier 11 and fall into the crushing unit to be re-crushed. Airflow is carried.

In the crushing apparatus having the above-mentioned structure, several coal adhesion accidents have been reported centering on the lower part of the coal feeding pipe 8. The clogging accident of the coal feeding pipe 8 is usually caused by the following causes. That is, coal contains minerals (usually referred to as ash) in addition to the combustible material, in particular,
A large amount of ash is contained in low-grade coal called sludge coal that is discharged during the process of coal preparation. Furthermore, the ash content of sludge charcoal often contains a large amount of clay such as kaolinite or muscovite. As is well known, the clay content has a property of strongly fixing and solidifying when dried in a state of being moistened with water, and therefore coal containing a clay part also has this property.

Most of these sludge coals are usually discarded as coal mine waste. However, a part of the sludge may be mixed with high-quality coal (high-calorie coal) for calorie preparation. Even if it is not coal mixed with sludge coal, there are relatively many coals that contain clay as soil in the coal field. As described above, the clay content has a property of strongly fixing and solidifying when dried in a state of being moistened with water, and therefore coal containing a clay part also has this property.

Coal is normally supplied to the crushing device 1 in a wet state, and is dried by hot air in the lower part of the coal feeding pipe 8. However, when the ash content of this coal contains clay, the coal feeding pipe is The inner wall of the lower part of No. 8 dries, and the clay content adheres. The adhesion layer gradually grows, and eventually the coal feeding pipe 8 is blocked or unusable.

As a means for solving such problems,
A device for attaching a scraping blade to the lower roller 9 to scrape the inner wall of the coal feeding pipe 8 by utilizing the rotation of the lower roller, or a scraping work using another power source has been proposed. There is. However, these devices have not been able to exert a sufficient effect because coal, particularly clay, adheres to the scraping blade itself.

As another means, instead of scraping off the adhered coal layer, water is made to flow down through the water injection pipe 2 and the water injection hole 3 to the inner wall of the coal feed pipe 8 in advance, and the clay content is also provided below the coal feed pipe 8. A method has been proposed to prevent it from drying and solidifying and has been effective. However, while this method can prevent the coal from adhering and solidifying, supplying water to the crushing device is an operation opposite to the drying of coal, so that the classification efficiency of the classifier 11 is reduced, There are problems such as deterioration of the combustibility of charcoal.

Therefore, an object of the present invention is to reduce the classification efficiency in the classifier and the combustibility of pulverized coal when the amount of water for preventing the blockage of the coal feeding pipe of the above-mentioned prior art is too large.
In order to solve the problems such as the increase in heat loss of the boiler due to the heat of evaporation of water, it is possible to effectively prevent the adhesion of coal to the coal feeding pipe, decrease the classification efficiency of coal and the combustibility of pulverized coal. It is an object of the present invention to provide a coal crusher without a crusher and a method for controlling a water injection amount of the coal crusher.

[0009]

According to the present invention, a water injector and a water injection hole are provided at the upper part of a coal feeding pipe for supplying coal to a crushing section, and a water pouring device and a water pouring hole are provided on the inner wall surface of the coal feeding pipe. A coal crushing device for crushing coal from a coal pipe, a pipe wall temperature detector for detecting a pipe wall temperature in the coal feeding pipe, a pipe wall temperature detection signal and a pipe wall temperature setting signal from the pipe wall temperature detector There is provided an arithmetic unit for comparing and, and a coal crushing apparatus is provided which is configured to increase or decrease the amount of water injected from the water injection hole based on the comparison result of the pipe wall temperature detection signal and the pipe wall temperature setting signal.

Further, according to the present invention, a water injector and a water injection hole for causing water to flow down are provided on the inner wall surface of the coal feeding pipe above the coal feeding pipe for supplying coal to the crushing section, and coal from the coal feeding pipe is supplied. In a coal crushing device for crushing a pipe, a pipe wall temperature detector for detecting a pipe wall temperature in the coal feeding pipe, and a calculator for comparing a pipe wall temperature detection signal from the pipe wall temperature detector with a pipe wall temperature setting signal Is provided to compare the pipe wall temperature detection signal with the pipe wall temperature setting signal,
When the pipe wall temperature setting signal is larger than the pipe wall temperature detection signal, the water injection amount from the water injection hole is increased, and when the pipe wall temperature setting signal is smaller than the pipe wall temperature detection signal, the water injection amount from the water injection hole is decreased. There is provided a method for controlling a water injection amount of a coal crushing device, which is controlled so as to perform the above.

The pipe wall temperature detector may be arranged adjacent to the inner wall of the coal feeding pipe, the outer wall or the inner wall of the coal feeding pipe, whether or not water is flowing, and whether fine coal powder is attached to the pipe wall. Whether or not it is detected by monitoring the temperature, and the amount of water for preventing adhesion is supplied on the basis of this.

[0012]

When water is heated, the temperature rises, but under a predetermined atmospheric pressure, the temperature does not rise above the temperature determined by the pressure, and the heat added at this temperature is consumed as latent heat of vaporization of water. To be done. Due to the physical properties of this water, when the coal adhering to the inner wall of the coal feeding 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 the amount of water injected into the crushing device be minimized to the minimum necessary, but also the abnormality of the water injection device can be detected early. be able to.

[0013]

1 is a schematic view of a coal crusher as an embodiment of the present invention, in which parts corresponding to those of the prior art shown in FIG. 4 are designated by the same reference numerals, which are a crusher body 1, a water injection pipe. 2, water injection hole 3, pressurizing device 4, thermocouple 5, upper fixed ring 6,
Crushing ball 7, coal feeding pipe 8, lower roller 9, classifier 11,
Swirl vane 12, pulverized coal pipe 13, drive device 15, water injector 1
6, including the air port 17, further the arithmetic unit 10, CRT
A screen 14, a valve 18, a water injection pump 19, a pipe wall temperature detection signal 20, and a pipe wall temperature setting signal 21 are also shown.

Before describing FIG. 1, experimental data conducted by the inventors will be described with reference to FIGS. 2 and 3. As shown in FIG. 3, a hole for inserting a thermocouple is provided from the outside of the coal feeding pipe as shown in FIG. 3, and a sheath thermocouple is inserted into the hole, and a pipe wall portion at a position 3 mm from the inner wall of the coal feeding pipe is provided. The temperature was measured and shown as the temperature distribution in the longitudinal direction of the coal feeding pipe,
When the fine powder during coal feeding does not adhere to the inner wall of the coal feeding pipe, the temperature of the pipe wall rises toward the lower part of the coal feeding pipe.
It is 0 ° C or lower.

On the other hand, when an adhesion layer of fine powder is formed on the inner wall of the coal feeding pipe, water flows on the surface of the adhesion layer, so that the coal feeding pipe cannot be directly cooled, and the inner wall of the coal feeding pipe is not able to be cooled. The temperature at a position slightly (about 3 mm) away from is higher than 100 ° C. by being heated by the air supplied to the pulverizer, as shown in FIG. That is, by utilizing this, it becomes possible to measure the temperature of the pipe wall of the coal feeding pipe to know the adhesion state of the fine powder to the inner wall of the coal feeding pipe, and the present invention utilizes this.

In FIG. 1, the crushed coal C drops in the coal feed pipe 8 of the crusher body 1 and reaches the crushing section. The crushing unit includes an upper fixed ring 6 to which pressure is applied by the pressure device 4.
And the lower roller 9 driven to rotate by the drive unit 15.
And a crushing ball 7 which is arranged between the upper fixed wheel 6 and the lower roller 9 and rolls as the lower roller 9 rotates. The coal that has reached the crushing section is moved to the position of the crushing ball 7 and crushed by the centrifugal force generated by the rotation of the lower roller 9. The crushed coal rises in the crusher main body 1 by the air supplied from the air port 17 (usually used as high-temperature air to also dry the coal). The air flow containing the crushed coal becomes a swirling air flow by the swirl vanes 12 installed at the inlet of the classifier 11, and large-diameter particles descend in the classifier 11 and fall into the crushing unit to be re-crushed to form fine powder. The charcoal flows into the pulverized coal pipe 13 together with the air flow and is conveyed to the pulverized coal burner (not shown) by the air flow.

Water for preventing the fine powder from adhering to the inner wall of the coal feeding pipe 8 (hereinafter referred to as "adhesion preventing pouring water") enters the pouring device 16 through the pouring pipe 2, and the pouring hole 3 feeds the coal feeding pipe 8
Go inside and run down the inner wall. The tube wall temperature of the coal feeding pipe 8 is measured by the thermocouple 5 inserted inside the wall of the coal feeding pipe 8 in the longitudinal direction of the coal feeding pipe 8. Further, a thermocouple 5 is also attached in the circumferential direction of the coal feeding 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, so that the water in the circumferential direction flows down. Monitor quantity uniformity.

The pipe wall temperature detection signal 20 detected by these thermocouples 5 is taken into the arithmetic unit 10 and the CRT 14
Displayed as temperature distribution above. This temperature distribution is monitored by an operator and compared with a normal pipe wall temperature setting signal 21 (temperature pattern) input to the arithmetic unit 10 in advance,
Calculate the maximum temperature difference from the normal temperature pattern. If the temperature difference is greater than the preset tolerance,
A signal is generated from the arithmetic unit 10 (which can also 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 also compared with the temperature pattern in the normal state that was input in advance, and calculation is performed, and if the temperature difference exceeds the preset allowable value, an alarm is generated Be careful of staff. Abnormalities in the temperature pattern in the circumferential direction are caused by a decrease in the water injection pressure, clogging of the water injection hole 3, and various other factors, so that on-site inspection and repair by the operator are often required.

[0019]

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

[Brief description of drawings]

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

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

FIG. 3 is a diagram showing the mounting of thermocouples arranged to measure the temperature distribution shown in FIG.

FIG. 4 is a view showing an example of a conventional coal crushing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Grinding device main body 2 ... Water injection pipe 3 ... Water injection hole 4 ... Pressurizing device 5 ... Thermocouple 6 ... Upper fixed ring 7 ... Grinding ball 8 ... Lower rolling wheel 10 ... Calculation device 11 ... Classifier 12 ... Swivel Blade 13 ... Pulverized coal pipe 14 ... CRT screen 15 ... Driving device 16 ... Water injector 17 ... Air port 18 ... Valve 19 ... Water injection pump 20 ... Pipe wall temperature detection signal 21 ... Pipe wall temperature setting signal

Claims (2)

[Claims] 1. A coal feeding pipe for supplying coal to a crushing unit,
Pipe wall temperature detection for detecting a pipe wall temperature in the coal feed pipe by providing a water injector and a water injection hole for flowing down water on the inner wall face of the coal feed pipe to form a coal crushing device for crushing coal from the coal feed pipe A vessel,
An arithmetic unit for comparing the pipe wall temperature detection signal from the pipe wall temperature detector and the pipe wall temperature setting signal is provided, and based on the comparison result of the pipe wall temperature detection signal and the pipe wall temperature setting signal, A coal crusher characterized by increasing and decreasing the amount of water injection. 2. An upper part of a coal feeding pipe for supplying coal to a crushing section,
In a coal crushing device for crushing coal from a coal feeding pipe by providing a water injector and a water injection hole on the inner wall surface of the coal feeding pipe, a pipe wall temperature detector for detecting the pipe wall temperature in the coal feeding pipe When,
An arithmetic unit for comparing the pipe wall temperature detection signal from the pipe wall temperature detector with the pipe wall temperature setting signal is provided, and the pipe wall temperature detection signal and the pipe wall temperature setting signal are compared. When the pipe wall temperature setting signal is large, the amount of water injected from the water injection hole should be increased, and when the pipe wall temperature setting signal is smaller than the pipe wall temperature detection signal, the amount of water injection from the water injection hole should be decreased. A method for controlling the water injection amount of a coal crusher, which is characterized by: