JPS62112693A - Production of coal-water slurry - Google Patents

Abstract

PURPOSE:To obtain a coal-water slurry which can be prepd. by the on-line method at low cost with high accuracy, by stimulating the viscosity of a slurry contained in a wet mill based on the data detected with respect to the driving current or driving power of the wet mill and controlling the amt. of the water to be fed in accordance with the viscosity. CONSTITUTION:Coal is fed from a coal hopper 1 through a metering feeder 2 into a cylindrical wet mill 3. Separately, water is fed from a water tank 11 trough a feed pump 10 into the cylindrical wet mill 3. The cylindrical wet mill 3 is driven by means of a mill driving motor 6 through a mill driving gear 4 and a reducer 5. The coal is mixed with water within the mill 3. The mixture is pulverized and is discharged in the form of a slurry. The discharged slurry is filtered with a filter 12 to remove foreign matter and is stored in a tank 13. In the above process, the electrical input of a mill driving motor is detected with a current detector 7. The value of the electrical input is input into the feed water controller 9. The amt. of water to be fed with a feed pump 10 is controlled with an output controlling signal from the feed water controller 9, thereby obtaining a slurry having a constant viscosity.

Description

[Detailed Description of the Invention] <Object of the Invention> Industrial Application Field The present invention relates to a method for producing a coal-water slurry, and more specifically, a coal-water slurry suitable for producing a slurry for CwM using a wet cylindrical mill. Relating to the manufacturing method.

Conventional technology A wet mill is a machine that produces slurry by grinding water and ground material in a cylindrical mill. Therefore, the manufactured product is a mixture of water and ground material, and a certain quality is required depending on the application.

An example of this is CWM (coal-water slurry), which has recently attracted attention as a liquid fuel, and a high concentration is desirable in terms of combustion efficiency.

On the other hand, the great advantage of these devices is that they can transport liquid using a vibrator. However, the higher the concentration, the more difficult it becomes to transport the vibrator and the pipe becomes sticky. Therefore, it is necessary to make a highly concentrated slurry without clogging the vibrator.

Generally, it is considered that the most desirable slurry for CWM is 65 to 70%, but in principle, to produce the above slurry, it is sufficient to supply a certain ratio of crushed coal and water.

However, compared to water, the properties of coal vary greatly depending on the region of production and even lofts of the same brand, making it impossible to produce high-quality slurry using a process that only supplies a fixed ratio. On the other hand, the phenomenon of pipe clogging is highly correlated with the viscosity of the slurry produced.

Therefore, it is conceivable to adjust the water supply amount by measuring the viscosity of the produced slurry or the agricultural degree (instead of the viscosity).

Conventionally, the above-mentioned technology has been proposed in Japanese Patent Application Laid-open No. 59
-8791 and Japanese Unexamined Patent Publication No. 59-182895. The former method involves producing a slurry with excess water in order to adjust it to the optimum concentration, as increasing the viscosity of the slurry makes it difficult to handle, and then heating this slurry to evaporate the water to obtain a slurry with a predetermined concentration. The latter measures the viscosity of the slurry downstream of the wet mill, and adjusts the feed rate of raw materials and water based on the measured viscosity.
A stable slurry is obtained by adjusting the residence time in the mill. Therefore, the former requires heating evaporation means to remove excess moisture, which is uneconomical, while the latter requires 1 to 2 hours of slurry residence time in the mill in industrial-based wet mills, and the amount of water supplied varies. However, it takes a long time for the results to appear as viscosity.

Therefore, it becomes complicated to accurately measure the viscosity, repeat the frequency, etc. for control purposes, and it is difficult to apply it to on-line production, so a simple means is required.

For the above reasons, it is difficult to continuously produce slurry with a constant viscosity in a wet mill, and the only operating method available is the greatest common divisor based on operation data analysis.

Problems to be Solved by the Invention The present invention aims to solve these problems, and specifically aims to provide a method for producing coal-water slurry that can be carried out inexpensively, accurately, and online. shall be.

<Structure of the Invention> Means for Solving the Problems and Their Effects The present invention detects the drive current or drive power of the mill when producing coal-water slurry using a wet mill, and detects the drive current or drive power of the mill. The slurry viscosity in the mill is estimated based on the value, and the water supply amount is controlled according to the estimated viscosity.

A more detailed explanation will be given below with reference to the drawings.

FIG. 1 is a flow sheet showing an example of the manufacturing method according to the present invention, FIG. 2 is a graph showing an example of the detection part of FIG. 1, and FIG. , and FIG. 4 is a graph showing an example of the control section of FIG. 1. FIG.

Recently, methods of detecting electrical physical quantities and using them as process detectors have been attracting attention (for example, estimating the hoisting load from the current value of the hoisting motor).

In addition, the electric quantity can be detected accurately and at extremely low cost. On the other hand, in a cylindrical mill or mixer, there is a correlation between the weight of the substance in the mill or mixer in the case of a dry type, the properties of the substance in the mill or mixer in the case of a wet type, and the power required to drive the mill or mixer. Particularly in an overflow type wet mill, the amount of slurry retained in the mill is a constant value determined by the structure of the mill, and when the slurry has a high concentration, there is a strong correlation between 17 M degrees and the mill driving force.

It has been found that by utilizing this characteristic, it is possible to indirectly detect the slurry viscosity by detecting the electrical input of the drive motor to determine the power required to drive the mill.

Therefore, by applying this principle, slurry of constant viscosity 'I
This led to the invention of the J'r7a method.

The configuration of the present invention is as follows: (1) In a wet cylindrical mill, the driving force of an electric motor for driving the mill is measured using an electrical physical quantity.

(2) (Estimate the viscosity of the slurry from the result of (11) or the processed value of the result of (1), and adjust the water supply amount online.

This is a method for producing a slurry with a constant viscosity through steps (1) and (2) above.

In FIG. 1, coal is supplied from a coal hopper 1 to a wet circular mill 3 via a theorem supply device 2. On the other hand, water is supplied from the water tank 11 to the wet cylindrical mill 3 via the water supply pump 10. The wet cylindrical mill 3 is driven by a mill drive electric motor G via a mill drive gear 4 and a reduction gear 5.

Coal and water are mixed inside the wet cylindrical mill 3, crushed, and discharged as a slurry. The discharged slurry is filtered to remove green matter through a filter 12, and then transferred to a slurry tank 1.
It can be stored in 3.

The slurry is then transferred by slurry pump 14 to slurry consuming equipment.

Figure 1 shows the basic flow of slurry manufacturing equipment.
The actual equipment includes a stirrer at key points, but this is omitted. In FIG. 1, the electrical input of the mill drive electric motor is detected by a current detector 7, the detected value is applied to a water supply amount controller 9, and the output control signal of the water supply amount controller 9 is used to control the amount of water supplied to the water supply pump 10. This method produces slurry with a constant viscosity by controlling the viscosity of the slurry.

Further, in FIG. 3, the horizontal axis represents the slurry concentration (% by weight), the vertical axis represents the slurry viscosity (curve II in the figure), and the current and power of the mill drive motor (curve ■ in the figure).

As is clear from these data, the slurry concentration is 55
% to 75%, the viscosity and the current and power of the mill driving motor are proportional to the slurry concentration.

Therefore, the viscosity of the slurry can be estimated by measuring the current or electric power of the mill drive motor. This shows that in a wet cylindrical mill, the required driving power varies depending on the slurry viscosity when the slurry concentration exceeds a certain value. Moreover, this phenomenon is caused by the structure of wet cylindrical mills, where the volume of slurry that stays in the mill is constant, and the change in the power required to drive the mill due to changes in specific gravity due to changes in slurry concentration is more important than changes in slurry concentration. This shows that the change in the required driving power due to the change in viscosity is extremely large. In particular, this phenomenon shows a remarkable tendency at slurry concentrations of about 55% or higher.
When the concentration exceeds a certain level, the viscosity of the slurry changes and the slurry adheres to the inner wall of the mill, but the amount of adhesion and the time it takes to drip after adhesion change depending on the rotation of the mill.

As can be explained from the phenomenon described above, in a wet cylindrical mill, there is a range in which the viscosity of the slurry produced and the power required to drive the mill exhibit a fairly good correlation. Furthermore, the range is t for high-concentration slurry required in CWM equipment, etc.
It matches well with 5I711. Therefore, as explained above, it is possible to produce a slurry having a constant viscosity by indirectly measuring the power required to drive the mill and using that value to control the water supply.

By using the present invention, it is possible to produce slurry with a constant viscosity, regardless of changes in coal properties caused by changes in production area or excavation period.

EXAMPLE A specific implementation method of the present invention will be explained using FIGS. 2 and 3.

FIG. 2 shows a method for electrically detecting the power required to drive a mill motor. In FIG. 2, the electric motor 6
is operated and stopped by the motor control AGI device 8. Also, W! For linear induction motor, secondary resistor 1G
is included. The driving power of the electric OR is extremely accurately determined by using the current detector 7 in FIG. 2 or by the power converter 15 that detects and converts current and voltage.
It can be detected in C and D. Normally, one of these detection signals may be used.

In general, wound type induction electric! In the case of a JIJ machine, it is not possible to detect the secondary side current or power, and in the case of a squirrel-cage induction motor, the secondary side cannot be detected, so the primary side current or power is detected and it is proportional to the driving power of the motor. It can be treated as an analog signal.

Further, even if the drive motor is of another type, it is possible to detect it using almost the same method.

Next, a method of controlling the water supply amount will be explained with reference to FIG.

The input water supply amount controller 94' in FIG. 4 is an analog quantity proportional to the driving power of the electric motor described in FIG. 2 and the reference signal of the setting device 21, and the output signal is a control signal. Therefore,
A commercially available controller may be used as the water supply amount controller. To control the water supply amount, the output signal of the water supply amount controller 9 described above may be passed through the discharge valve regulator 17 to adjust the opening degree of the discharge valve 18, or the output signal may be changed to a variable voltage variable frequency The rotational speed of the pump driving electric VJ machine that drives the water supply pump 10 via the device 20 may be changed.

As explained above, if a control output signal can be obtained, it is fully possible to control the water supply amount with the current technology.

With the configuration described above, by using the method according to the present invention, it was possible to produce a slurry of a desired constant viscosity with great precision.

In addition, the mill electric power explained above! The method of electrically detecting the power required to drive the i13 aircraft and the method of controlling the amount of water supply are just examples, and the present invention is not limited thereto, and other suitable methods may be used.

<Effects of the Invention> As explained above, the present invention detects the drive current or drive power of the mill when producing coal-water slurry using a wet mill, and detects the drive current or drive power of the mill based on the first shift of detection. This is a slurry manufacturing method in which the slurry viscosity in a mill is estimated and the water supply amount is controlled according to the estimated viscosity. It is possible to produce slurry with a constant viscosity that remains stable against changes in temperature, etc.

This means that, for example, in CWMiQ equipment, it is possible to produce a slurry with the highest pipe transport efficiency and a slurry with the highest combustion efficiency.

[Brief explanation of drawings]

FIG. 1 is a flow sheet showing an example of the manufacturing method according to the present invention, FIG. 2 is a graph showing an example of the detection section in FIG. 1, and FIG.
The figure is a graph showing the correlation between the concentration, viscosity, current, and power of coal-water slurry, and FIG. 4 is a graph showing an example of the control section of FIG. 1. Sign @1... Coal hopper 2... Constant supply device 3... Wet cylindrical mill 4... Mill drive gear 5... Reducer C... Mill drive motor 7... Current detector 8... Motor control device 9... Water supply controller 10...・Water supply pump 11...Water tank 12...
Filter 13...Slurry tank 14...Slurry pump 15...Power converter 1G...Secondary resistor 17...Discharge valve adjustment Vessel 18...
・Discharge valve 19...Pump drive motor 20...Variable voltage, variable frequency device 21...
...Setting device

Claims (1)

[Claims] When producing coal-water slurry using a wet mill,
Production of a coal-water slurry characterized by detecting the driving current or driving power of the mill, estimating the viscosity of the slurry in the mill based on the detected value, and controlling the amount of water supplied according to the estimated viscosity. Method.