JPH0687988B2 - Wet ball mill controller - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a wet ball mill control device, and particularly to a wet ball mill suitable for maintaining a constant concentration, viscosity, viscosity, etc. of high-concentration coal-water slurry. Control device.

[Conventional technology]

High-concentration coal / water slurry (hereinafter CWM (Coal Water Mixtut
abbreviated re)] is a fuel in which a small amount of water and a small amount of additives are mixed in coal and finely pulverized to a particle size that enables direct combustion. Mainly, the characteristics of CWM for pulverized coal fuel are listed below. become.

(1) It can be transported, stored and burned as liquid fuel.

(2) Direct combustion is possible without dehydration.

(3) Operation of fuel system (operation / control) is easy.

The coal concentration in CWM is a high concentration of about 60% or more, and the particle size is adjusted so that the 200 mesh passage amount is about 70 to 90%. In addition, it must be a stable, low-viscosity liquid that can be pumped.

The conditions for producing a stable CWM having a high slurry concentration and a low viscosity are as follows.

(B) The packing density of particles is increased by adjusting a wide range of particle size distribution to achieve high concentration.

(B) Addition of a dispersant forms a water film on the surface of the particles and charges them to disperse the particles to reduce the viscosity.

In the case of continuously producing such a CWM, generally, a production facility using a continuous wet ball mill as shown in FIG. 6 is used.

In FIG. 6, a coal feeder 2 is provided below the bunker 1 to which the coal A is supplied, and this coal feeder 2 has a coal flow meter 3
Is provided. A pump 5 for supplying the water in the tank to the ball mill 10 is connected to the water tank 4 to which the water B is supplied, and a water flow meter 6 is provided downstream of the pump 5.
Is provided. Further, a pump 8 for supplying the additive liquid C to the ball mill 10 is connected to the additive tank 7 to which the additive liquid C is supplied, and an additive flow meter 9 is provided on the downstream side of the pump 8. It is provided.

Gear A is provided on the outer periphery of the ball mill 10 which receives coal A, water B, and additive liquid C, and mixes, grinds, and granulates them.
11 is provided, a pinion shaft 12 is provided so as to mesh with the gear 11, and a motor 13 is provided directly connected to the pinion shaft 12. On the outlet side of the mill 10, a tank 14 equipped with a level gauge 15 is arranged to receive the CWM. Tank 1
The CWM in 4 is supplied to the coarse-grain separator 19 by the slurry pump 16, and a flow meter 17 and a pycnometer 18 are arranged in the middle of the supply path. A coarse grain slurry line 22 for returning the coarse grain slurry to the mill 10 again is provided between the coarse grain separator 19 and the ball mill 10. Further, the product slurry in the coarse particle separator 19 is taken out via the product slurry flow meter 21.
20 is a coarse-grained slurry flow meter.

In the above structure, the coal A is supplied from the bunker 1 to the ball mill 10 via the coal feeder 2. Similarly, water B and additive C are supplied to ball mill 10 by pumps 5 and 8 from water tank 4 and additive tank 7, respectively. The CWM produced in the ball mill 10 is discharged to the tank 14 and supplied to the coarse particle separator 19 by the slurry pump 16. The coarse particle separator 19 collects coarse particles unsuitable as a product, supplies the coarse particles to the ball mill 10, and re-pulverizes them. On the other hand, the product is taken out from the coarse-grain separator 19 and the product tank (not shown)
Etc.

In this way, the CWM is continuously produced, but in order to produce a stable CWM having a predetermined concentration and low viscosity, the inside of the ball mill 10 is maintained at an appropriate slurry concentration and particles are It is necessary to properly control the residence time of crushing and crush.

However, the properties of the coal A supplied to the ball mill 10, such as the particle size, water content, and pulverizability, vary from moment to moment. In accordance with this, the concentration, particle size and viscosity of the product CWM that has passed through the coarse particle separator 19 vary. For this reason, equipment shutdown or good quality CW
Continuous production of M becomes difficult. For example, when the water content of coal A suddenly decreases, the slurry concentration in the ball mill 10 increases, which increases the slurry viscosity, increases the slurry hold-up amount in the ball mill, and increases the movement of the balls in the mill. It is suppressed and the crushing ability is reduced. In addition, the CWM concentration and viscosity at the outlet of the ball mill 10 increase, and the particle size becomes coarse. Also, if the viscosity in the ball mill 10 becomes too high, the movement of the slurry in the mill 10 will stop,
The ball mill 10 is closed.

In order to prevent such problems and troubles, the conventionally proposed method measures the concentration, viscosity and particle size of CWM at the outlet of the ball mill 10 by sampling, and feeds back the result to the mill operation amount to operate the mill. It was something to control.

[Problems to be solved by the invention]

However, in the conventional ball mill control method, the residence time in the ball mill is long (1-2 hours), and when the measurement time of slurry concentration and viscosity is included, the property fluctuation of the product CWM due to the property change of coal is corrected. At least 2 for
It takes ~ 3 hours and there is a problem that quality control becomes difficult. Further, the technique for measuring the particle size or particle size distribution of high-concentration CWM online has not been established, and automatic control of a wet ball mill was extremely difficult.

The object of the present invention is to solve the above-mentioned problems of the prior art,
It is an object of the present invention to provide a ball mill control device capable of continuously monitoring the slurry hold-up amount in a mill and always obtaining a CWM having a desired concentration, particle size and viscosity.

[Means for solving problems]

In order to achieve the above object, the present invention, in a wet ball mill, the total of coal, water and additives to the mill is divided by the sum of the slurry flow rate change value of the tank provided on the outlet side of the mill and the product slurry amount. A calculation unit for calculating the change rate of the slurry holdup amount and a control unit for controlling the water supply amount or the coal supply amount for the mill so that the change rate of the slurry holdup amount maintains a constant value. is there.

[Action]

By continuously monitoring the hold-up amount that fluctuates in proportion to the CWM coal concentration and slurry particle size, the mill's operating status can be grasped, and by maintaining the hold-up amount at a constant value, the mill will be blocked or stopped. CW without
M can be continuously produced.

〔Example〕

 An embodiment 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. In FIG. 1, the same reference numerals are used for the same components as those in FIG. 6, and thus duplicated description will be omitted. The present invention includes the output Fc of the coal flow meter 3, the output Fw of the water flow meter 6, and the additive flow meter 9
Output Fa, specific gravity meter 18 output, coarse grain slurry flow meter 20 output, tank level meter 15 output and product slurry flow meter 21
A calculation unit 23 for calculating the change rate P of the slurry holdup amount in the ball mill 10 based on each output Fs of the ball mill 10 and a control unit 25 for controlling the operation of the pump 5 based on the calculation result of the calculation unit 23 are provided. Consists of

Since the manufacturing process of the CWM is as described above, the description thereof is omitted, but the calculation unit 23 uses the output of each measuring device and continuously executes the calculation by the following formula to change the slurry hold-up amount in the ball mill 10. The rate (deviation value) P is calculated.

However, Fc: Coal amount (t / h) Fw: Water amount (t / h) Fa: Additive amount (t / h) Fs: Product slurry amount (t / h) A: Tank area (m ² ) Hn: Time Tank level at Tn (m) Hn _-1 : Time at Tn _-1 (m) Tn: Time (h) ρs: Slurry density (t / m ³ ) The calculation unit 23 has a fixed time (Tn-Tn _-1 ). The change in the tank level (Hn-Hn- ₁ ) is measured for each. The numerator in the equation (1) is the amount of coal supplied to the mill 10, the amount of water, and the amount of additives, and the denominator shows the change in the slurry flow rate in the tank 14 at time (Tn-Tn _-1 ). The slurry level in the tank 14 is continuous because fluctuations in the slurry pump 16 (variation in the amount of slurry supplied even if the pump speed is constant due to line pressure, blockage, etc.) and fluctuations in the capacity of the coarse-grain separator 19 occur continuously. Need to detect.

In equation (1), P = 0 during steady motion, and the mill 10
There is no change in the hold-up amount in the inside, and P> 0 is mil 10
Shows the decrease state of the hold-up amount Us in
The increase in the hold-up amount Us within 10 is shown. Arithmetic section
By controlling the amount of water supplied to the ball mill 10 by the control unit 25 of the pump 5 based on the calculation result of 23, the hold-up amount Us is maintained at a constant value (P = 0, That is, the slurry viscosity can be kept constant). By the way, it can be seen that the case where the control according to the present invention is not performed is the hold-up amount change rate characteristic of FIG. 3 and changes with the passage of time.

In FIG. 1, the control unit 25 controls the water supply amount Fw, but the coal supply amount may be controlled.

Since CWM increases the coal concentration to the limit that can be expected from the powder theory, as shown in Fig. 4, the viscosity, that is, the fluidity, changes greatly with a slight change in the coal concentration. This viscosity varies depending on the type of coal, especially the water supply rate, and the slurry viscosity rapidly increases as the coal concentration increases. When the viscosity of the slurry increases, the slurry is accompanied by a chalking phenomenon in the mill 10, and the mill 10 has to be stopped.

FIG. 5 is a characteristic diagram showing the relationship between the slurry viscosity and the slurry holdup amount Us in the mill 10. Hold-up amount Us
Influences the slurry viscosity regardless of the type of coal, and as the slurry viscosity increases, the hold-up amount Us amount in the mill 10 also increases. Especially when the slurry viscosity is about 2000 cP or more, the mill
Hold-up amount of slurry because it will be blocked within 10
Us measurement is important. As described above, in the operation of the ball mill 10, by measuring the hold-up amount Us in the mill 10, the coal concentration of CWM or the slurry viscosity can be estimated.

As shown in FIG. 7, the mill 10 is provided with a partition plate 27 inside. Therefore, the fluid supplied to the mill 10 receives resistance by the partition plate 27, and since the additive is supplied to each of the inlet portion and the outlet portion of the mill 10, the mill inlet is compared to the outlet of the mill. Partial coal concentration and slurry viscosity are high.

Further, since coal is supplied to the inlet of the mill, coarse particles are often retained, and the slurry viscosity becomes high as shown in FIG. From the above, the hold-up amount Us in the mill 10
As shown in FIG. 9, the first chamber of the mill 10 is closed as shown in FIG. However, by constantly measuring the hold-up amount in the mill 10, the clogging trouble can be quickly grasped.

The hold-up amount Us in the mill is expressed by the following equation.

However, 0.4: space ratio of balls ρs: slurry density V: mill volume J: ball filling rate W: slurry volume in mill In order to further improve the accuracy in the present invention, the time and P shown in FIG. This can be realized by integrating the value relationship diagram and continuously calculating the integrated value (≈absolute value) of the holdup amount in the mill 10.

〔The invention's effect〕

As described above, according to the present invention, since it is possible to continuously monitor the change in the hold-up amount in the mill, the concentration, particle size, and viscosity of the high-concentration coal-water slurry are maintained constant, and a high-quality slurry is obtained. It can be manufactured continuously.

[Brief description of drawings]

FIG. 1 is a system structure diagram showing the primary of the present invention, FIG. 2 is a holdup amount change rate characteristic diagram according to the present invention, FIG. 3 is a conventional holdup amount change rate characteristic diagram, and FIG. Slurry viscosity characteristic diagram, FIG. 5 is a characteristic diagram of hold-up amount with respect to slurry viscosity, FIG. 6 is a configuration diagram showing a conventional CWM manufacturing system, FIG. 7 is a sectional view showing a schematic configuration in the ball mill 10, and FIG. Is a slurry particle size and slurry viscosity distribution characteristic diagram in the mill, and FIG. 9 is an explanatory diagram of the mill blockage. 1 ... bunker, 2 ... coal feeder, 3 ... coal flow meter, 4 ...
… Water tank, 5, 8 …… Pump, 6 …… Water flow meter, 7…
… Additive tank, 9 …… Additive flow meter, 10 …… Ball mill, 14 …… Tank, 15 …… Level meter, 16 …… Slurry pump, 17 …… Flow meter, 18 …… Specific gravity meter, 19 …… Coarse grain separator,
20 …… Coarse grain slurry flowmeter, 21 …… Product slurry flowmeter, 23
…… Calculator, 25 …… Control unit.

Claims (1)

[Claims] 1. A wet ball mill for producing a coal-water slurry by slurrying coal with an additive and water to produce a slurry of coal-water, wherein the total amount of coal, water and the additive to the mill is provided on the outlet side of the mill. A calculation unit for calculating the change rate of the slurry holdup amount by dividing the sum of the slurry flow rate change value of the tank and the product slurry amount; and the mill so that the change rate of the slurry holdup amount maintains a constant value. A control unit for a wet ball mill, which is provided with a control unit for controlling the amount of water supply or the amount of coal supply to the.