JPS637852A - Control unit of wet ball mill - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a control device for a wet ball mill, and in particular, a wet ball mill suitable for maintaining constant the concentration, particle size, viscosity, etc. of a highly concentrated coal-water slurry. Regarding the control device. [Conventional technology] Highly concentrated coal/water slurry [hereinafter referred to as CWM (CoalWate)]
Mixtutre) is a fuel made by mixing coal with a small amount of water and a small amount of added soybean, and pulverizing it to a particle size that can be directly combusted.The main characteristics of CWM for pulverized coal fuel are as follows. It becomes like this. (1) Can be transported, stored, and burned as a liquid fuel. 《
2》 Direct combustion possible without dehydration. 《3》 Easy fuel system operation (operation and control). The coal concentration in CWM is high, about 60% or more, and its particle size is 2.
The amount of passage through the 00 mesh is adjusted to approximately 70 to 90%. It also needs to be a stable, low-viscosity liquid that can be pumped. The conditions for producing stable CWM with high slurry concentration and low viscosity are as follows. (b) Increase the packing density of particles by adjusting the wide particle size distribution to achieve high concentration. (Note) By adding a dispersant, a water film is formed on the particle surface and charged, causing the particles to separate from each other and lowering the viscosity. When manufacturing such a CWM continuously, generally,
As shown in Figure 6, manufacturing equipment using a continuous wet ball mill is used. In FIG. 6, a coal feeder 2 is provided at the bottom of a bunker 1 to which 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 water B is supplied, and a water flow meter 6 is provided downstream of the pump 5. 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.
An additive flow meter 9 is installed on the downstream side. A gear 1l is disposed on the outer periphery of a ball mill IO that receives coal A, water B, and additive liquid C, and mixes, pulverizes, and pulverizes the coal. A motor 13 is provided directly connected to the two-on shaft 12. At the outlet of the mill 10, a tank 14 equipped with a level gauge 15 is arranged to receive CWM. CWM in tank 14 is slurry pump 1
6 to the coarse particle separator 19, and a flow meter 17 and a hydrometer 18 are disposed in the middle of the supply path.
A coarse slurry line 22 for returning the coarse slurry to the mill 10 is provided between the coarse grain separator a19 and the ball mill 10. Further, the product slurry in the coarse particle separator 19 is taken out via a product slurry flow meter 21. Sho 2
0 is a coarse slurry flowmeter. In the above configuration, coal A is supplied from bunker 1 to coal 812
It is supplied to the ball mill 10 via. 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 into a tank 14 and supplied to a coarse separator 19 by a slurry pump l6. A coarse grain separator 19 collects coarse grains unsuitable for use as a product, supplies them to a ball mill 10, and re-pulverizes them. Meanwhile, the product is taken out from the coarse separator 19 and stored in a product tank (not shown) or the like. In this way, CWM is produced continuously, but in order to produce stable CWM with a predetermined concentration and low viscosity, it is necessary to maintain an appropriate slurry concentration in the ball mill 10 and to
It is necessary to appropriately control the residence time of particles to crush them.
However, the properties of the coal A supplied to the ball mill IO, such as particle size, moisture content, and crushability, change from moment to moment. Accordingly, the concentration, particle size, and viscosity of the product CWM that has passed through the coarse particle separator 19 vary. This makes it difficult to stop the equipment or to continuously produce high-quality CWM. For example, if the moisture content of coal A suddenly decreases, the slurry concentration in the ball mill IO increases, which increases the slurry viscosity and increases the amount of slurry holdup in the ball mill.
The movement of the balls in the mill is suppressed, reducing the grinding capacity. In addition, the CWM concentration and viscosity at the outlet of the ball mill 10 become higher, and the particle size becomes coarser. Furthermore, if the viscosity within the ball mill 10 becomes too high, the movement of the slurry within the mill 10 will stop and the ball mill 10 will become clogged. In order to prevent such malfunctions and troubles, the conventionally proposed method is to reduce the concentration of CWM at the outlet of the ball mill 10,
The viscosity and particle size were sampled and measured, and the results were fed back to the mill operating inputs to control the mill operation. [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 to 2 hours), and when the time for measuring slurry concentration and viscosity is included, the coal There is a problem in that it takes at least 2 to 3 hours to correct changes in the properties of the product CWM due to changes in properties, making quality control difficult. Furthermore, the technology for online measurement of particle size or particle size distribution of high-concentration CWM has not been established, and automatic control of wet ball mills has been extremely difficult. The purpose of the present invention is to solve the problems of the prior art described above,
The object of the present invention is to provide a control device for a ball mill that continuously monitors the amount of slurry hold-up in the mill so that CWM of desired concentration, particle size, and viscosity can be obtained at all times. ] In order to achieve the above object, the present invention, in a wet ball mill, calculates the total amount of coal, water, and additives for the mill by the sum of the change in slurry flow rate in a tank provided on the outlet side of the mill and the amount of product slurry. A calculation unit that calculates the rate of change in the amount of slurry hold-up by division, and a control unit that controls the amount of water or coal fed to the mill so that the rate of change in the amount of slurry hold-up maintains a constant value. It is. [Function] By continuously monitoring the varying hold-up amount proportional to the CWM coal concentration and slurry particle size, the operating status of the mill can be grasped, and by maintaining the hold-up amount at a constant value, mill blockage, Do not cause suspension.
CWM can be manufactured continuously. [Example] Hereinafter, an example of the present invention will be described based on the drawings. Figure 1 is a sectional view showing an embodiment of the present invention. In Figure 1, the same reference numerals are used for the same components as in Figure 6, so duplicate explanations will be omitted. The present invention includes the output Fc of the coal flowmeter 3, the output Fw of the water flowmeter 6, the output Fa of the additive flowmeter 9, the output of the hydrometer 18, the output of the coarse slurry flowmeter 20, and the output of the tank level meter 15. and the ball mill 1 based on each of the output Fs of the product slurry IT meter 21.
The system includes a calculation section 23 that calculates the change rate P of the slurry hold-up amount within 0, and an iilHil section 25 that controls the operation of the pump 5 based on the calculation result of the calculation section 23. Since the CWM manufacturing process is as described above, the explanation will be omitted, but the calculation unit 23 uses the output of each measuring device to continuously perform calculations according to the following formula, and calculates the change in the amount of slurry holdup in the ball mill 10. Calculate the ratio (deviation value) P. Fs + (A (In −In −+) ρm )
/(Tn 4n-+)・・・・・・・・・・・・(1
) 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!) Hn : Tank level (m) at time Tn} {n-1
: Time Tn-. Tank level (m) Tn: Time (h) ρS: Slurry density (t/m3) The calculation unit 23 calculates the change in tank level (H n - H n-+) at every fixed time (7n'rn-+). Measure. The numerator in equation (1) is the amount of coal, water, and additive supplied to the mill 10, and the denominator is time (Tn −Tn−
+) shows the change in slurry mit in the tank 14. The slurry level in the tank 14 is determined by fluctuations in the slurry pump 16 (the amount of slurry supplied changes even if the pump rotation speed is constant due to line pressure, blockage, etc.) and the coarse particle separator 1.
9. Since fluctuations in performance always occur, it is necessary to detect them continuously. In formula <<1>>, during steady operation, P = O, there is no change in the amount of holdup in the mill IO, and P
>O indicates a decreasing state of the hold amplifier amount Us in the mill 10, and P0 indicates an increase in the hold amplifier amount Us in the mill 10. Based on the calculation results of the calculation unit 23, the control unit 25 controls the amount of water supplied to the ball mill lO by the pump 5, I? 11, the hold amplifier amount Us can be kept at a constant value (P-0, that is, the slurry viscosity is constant) regardless of the passage of time, as shown in FIG. Incidentally, when the control according to the present invention is not implemented, the hold-up amount change rate characteristic shown in FIG. 3 is the same, and it can be seen that it fluctuates with the passage of time. In addition, in FIG. 1, the water supply amount Fw is controlled by the control unit 25.
However, it is also possible to control the amount of coal fed. In CWM, the coal concentration is increased to the limit that can be expected from powder theory, so as shown in Figure 4, the viscosity, or fluidity, changes significantly with a very small change in coal concentration. This viscosity varies depending on the type of coal, especially the water supply rate, and as the coal concentration becomes thicker, the slurry viscosity increases rapidly. When the slurry viscosity increases, the slurry undergoes a ticking phenomenon in the mill 10, and the mill 10 must be stopped. FIG. 5 is a characteristic diagram showing the relationship between slurry viscosity and slurry hold-up amount Us in the mill 10. The hold-up amount US affects the slurry viscosity regardless of the type of coal, and as the slurry viscosity increases, the hold-up amount US in the mill IO increases.
The amount also increases. In particular, when the slurry viscosity exceeds about 2000 cP, the mill 10 becomes clogged, so it is important to measure the hold amplifier amount U3 of the slurry. In this manner, during operation of the ball mill 10, by measuring the hold amplifier amount Us within the mill 10, the coal concentration or slurry viscosity of the CWM 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 is resisted by the partition temporary 27, and the fluid supplied to the mill 10 is
Since additives are supplied to each of the inlet and outlet of the
The coal concentration and slurry viscosity at the mill inlet are higher than at the mill outlet. Furthermore, since coal is supplied to the mill population, there is a large accumulation of coarse particles, which increases the slurry viscosity as shown in Figure 8. From the above, when the hold amplifier amount Us in the mill 10 increases, the first chamber of the mill 1O becomes closed as shown in FIG. However, by constantly measuring the amount of holdup inside the mill 10, blockage problems can be quickly detected. The hold-up amount Us in the mill is expressed by the following formula, and the ball space volume in the mill is 0.4VJ・・・・・・・・・・・・
・(2) However, 0.4: Ball porosity p3: Slurry density V: Mill volume J: Ball filling rate W: Slurry volume in the mill In order to further improve the accuracy in the present invention, please refer to Fig. 3. This can be achieved by integrating the relationship diagram between time and P value shown in Figure 2, and continuously calculating the integrated value (absolute S value) of the hold-up amount in the mill IO. [Effects of the Invention] As described above, according to the present invention, changes in the amount of hold amplifier in the mill can be continuously monitored, so that the concentration, particle size, and viscosity of the highly concentrated coal-water slurry can be maintained constant. , it is possible to continuously produce high-quality slurry.

[Brief explanation of the drawing]

Fig. 1 is a system configuration diagram showing the first stage of the present invention, Fig. 2 is a characteristic diagram of the change rate of holdup amount according to the present invention, Fig. 3 is a characteristic diagram of the change rate of holdup amount of the conventional method, and Fig. 4 is a graph showing the change rate of holdup amount according to the present invention. Slurry viscosity characteristic diagram, Figure 5 is a hold amplifier amount characteristic diagram with respect to slurry viscosity, Figure 6 is a configuration diagram showing a conventional CWM manufacturing system, Figure 7 is a sectional view showing a schematic configuration inside the pole mill 10, and Figure 8. Figure 9 is a characteristic diagram of slurry particle size and slurry viscosity distribution in the mill, and Figure 9 is an illustration of mill blockage. 1... Bunker, 2... Coal feeder, 3
...Coal flow meter, 4...Water tank,
5, 8... Bomb, 6... Water flow meter, 7... Additive tank, 9... Additive flow meter, 10... ...Paul Mill, 14.
... Tank, 15 ... Level meter,
16... Slurry pump, 17...
Flow meter, 18...Hydrometer, l9...
・Coarse particle separator, 20... Coarse particle slurry flowmeter,
21... Product slurry flow meter, 23...
...Arithmetic section, 25...Control section. Agent Patent Attorney Katsuichi Nishimoto Figure 1 ^ Figure 2 Figure 3 Ill (mint y, between (m
in) -a-Figure 4 Figure 5 Slurry rice 'li/l (cPl Figure 6 C lb Figure 7 Dot10

Claims (1)

[Claims] (1) In a wet ball mill that generates a coal-water slurry in which coal is slurried with additives and water, the total amount of coal, water, and additives for the mill is stored in a tank provided on the outlet side of the mill. a calculation unit that calculates the rate of change in the amount of slurry holdup by dividing the change value of the slurry flow rate by the sum of the product slurry amount; and a water supply unit for the mill so that the rate of change in the amount of slurry holdup maintains a constant value. A control device for a wet ball mill, characterized in that it is provided with a control section that controls the amount or amount of coal fed.