JPH0696122B2 - Vertical mill control method and apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vertical mill control method and apparatus for crushing cement raw materials and agglomerates of limestone, and more specifically, to stable operation of the mill. The present invention relates to a control method and an apparatus for maximizing the mill crushing ability.

[Conventional technology]

The vertical mill is configured as shown in FIG. 5, and the crushed product is crushed in the following process.

The crushed material is extracted from the storage tank 1 and supplied in a fixed amount (hereinafter PM
2), a predetermined amount is weighed and supplied to a table 4 in the mill through a charging chute 3. The table 4
A plurality of crushing rollers 5 that rotate in cooperation with the rotation of the table are installed on the top. The pulverized material on the table 4 is crushed by the centrifugal force generated by the rotation of the table 4.
While being moved to the circumference of the circle, it is bitten by the crushing roller 5 and crushed and crushed, and is discharged from the table edge to the blow-up part 6 formed between the outer circumference of the table and the mill body.

In addition, a hot gas 7 for drying the raw material is introduced into the lower part of the mill main body, and the pulverized products discharged from the table 4 having a small particle size pass through the blow-up part 6 from below the table 4. Is conveyed along with the gas flow blown upwards to the classifier 8 and classified into coarse powder and fine powder, and the coarse powder falls in the mill and is returned to the table 4.
The fine powder is discharged out of the mill together with the hot gas 7 as a product.
On the other hand, the crushed material with a coarse particle size that did not ride on the hot gas flow falls below the table 4, is discharged by the mill body, is transported to the storage tank 1 by a transport machine such as a bucket elevator 9, and is newly supplied. It is taken out by PM2 together with the object and returned to the table 4 through the chute 3.

The operation control of the mill is a PM2 variable speed motor so that the difference between the static pressure of the hot gas introduced into the mill body and the static pressure of the gas discharged outside the mill (hereinafter referred to as the mill differential pressure) becomes constant. The set value of the rotation speed is controlled, and the feeder controls the speed of the feeder so as to reach this set value. Fast, the detector 10 for detecting the mill differential pressure, the differential pressure transmitter for converting the detection value of the detector 10 into an electric signal, the deviation between the signal sent and the set value is detected, and the deviation value is To eliminate the deviation between the differential pressure controller that outputs the set value of the rotational speed of the PM variable speed motor so that it becomes zero, and the set value that is output from the differential pressure controller.
It consists of a PM controller that controls the belt speed of the PM.

Further, the operator changes the set value of PM2 so that the table drive power and the drive power value of the bucket elevator (hereinafter referred to as circulation BE) fall within a certain range.

Since normal mill crushing is performed by drying and crushing at the same time, hot gas 7 is sucked into the mill, and waste heat from a normal firing furnace or the like is used as this hot gas source. In this case, the temperature of the sucked gas changes greatly, and the amount of sucked gas also fluctuates accordingly.Therefore, the mill outlet gas temperature is detected by the gas thermometer 11, and the water spray control in the mill is performed so that the outlet gas temperature becomes constant. It controls the vessel 12.

[Problems to be Solved by the Invention]

The factors of variation in the operating conditions of the mill are the water content of the pulverized material, the particle size composition, the physical properties of the pulverized material such as pulverizability, the temperature change of the suction gas and the change of the fineness of the product. In particular, when the physical properties of the pulverized material change, the amount of bite into the roller changes, the amount of pulverized material on the table, that is, the layer thickness on the table changes, and the amount of overflow from the table to the blow-up part changes. . When this amount fluctuates, the amount of pulverized material conveyed to the gas in the mill changes, and the internal circulation amount in the mill also changes, and the mill differential pressure changes. When the layer thickness of the pulverized material on the table changes, the driving power value of the table and the power value of the circulating BE also change.

Furthermore, since the mill outlet gas temperature, that is, the inlet gas temperature of the mill suction fan 13 also changes with the change of the gas inlet temperature of the gas sucked into the mill, the suction gas amount changes, and the dry condition of the pulverized material in the mill changes. Fluctuates, the amount of bite into the crushing roller fluctuates, and the layer thickness of the crushed material on the table changes,
The operation status becomes unstable due to fluctuations in the mill differential pressure. As a countermeasure for this, the amount of water sprinkled into the mill is controlled so that the temperature of the gas at the outlet of the mill is constant.However, since there is a response delay between the amount of water sprinkled and the outlet temperature, the current PID (proportiona)
Some fluctuations could not be avoided by controlling by integral and differential) arithmetic.

Even when the fineness of the product is changed, each detected value fluctuates in the same manner as described above, and the operator must change the set value so that the mill pulverization amount becomes the maximum, and always pay close attention and the fluctuation factor. It was necessary to infer how one element of the other would change when the other changed, which required abundant experience and comprehensive judgment.

[Means for Solving the Problems]

In order to solve the above-mentioned problems and develop a control method and device which have good operability and maximize the milling ability of the mill, as a result of various studies, the following control method and its device were developed. Came to do.

(A) Control method As a control method, the following three items were controlled by the mill.

 Control of pulverized material supply.

 Controlling the amount of water sprinkled in the mill.

 Control of oil pressure of crushing roller.

The reference values of the above controlled objects are fuzzy inferred by a computer, and each value is controlled to be equal to the reference value. Ie.

 Control of pulverized material supply.

Vibration value of crushing roller or mill, table drive power value,
The power value of the circulating BE and its rate of change, and each value of the mill differential pressure are input to the computer as input variables, and the pulverized material is supplied within the allowable limit of the table drive power value based on the fuzzy theory input in advance. Based on the control rule and the optimum value of each variable determined to maximize the amount, the fuzzy inference of the PM supply amount reference value by a computer so that each variable approximates the optimum value,
The result is output to the supply amount controller as a reference value of the pulverized material supply amount, and the controller controls the supply amount so as to match the supply amount reference value.

 Controlling the amount of water sprinkled in the mill.

Milling roller or mill vibration value, mill inlet gas temperature change rate, mill outlet gas temperature and each change rate value are input to the computer as input variables, and the mill exit gas based on the fuzzy theory that was input in advance. Based on the control rule that was set so that the temperature was constant and the optimum value of each variable, a fuzzy inference was made on the reference value of the water sprinkling amount in the mill by a computer so that each variable approximated to the optimum value. The amount of water is output to the water spray controller as a reference value, and the controller controls the water spray so that it matches the water spray reference value.

 Control of crushing roller oil pressure.

Each value of the crushing roller or mill vibration value, the table driving power value, the crushing roller lift amount and / or the crushing roller rotation speed is input to the computer as an input variable, and the crushing roller list amount and / or the previously input value are input. Based on the control rule that regulates the rotation speed of the crushing roller and the table drive power value and the optimum value for each variable, a fuzzy computer calculates the reference value of the crushing roller pressing pressure so that each variable approximates the optimum value. This is inferred and the result is output to the pressing hydraulic pressure controller, and the controller controls the crushing roller pressing oil pressure so as to match the hydraulic pressure reference value.

(B) Control device Next, the control device that enables the method of the present invention to be suitably implemented is: vibration value of crushing roller or mill body, table drive power value, mill differential pressure value, mill inlet / outlet gas temperature, circulation BE (bucket elevator) power value, grinding roller lift amount and /
Or, each measuring device of the rotation speed of the crushing roller, the mill outlet gas temperature and the electric power value of the circulation bucket elevator or the rate of change of each of them are calculated, and a fuzzy variable based on the fuzzy theory of each of the preset values, and the variable From the combined control rules and the measured values and calculated values, the reference value of the pulverized material supply amount or the sprinkling amount in the Mali or the crushing roller pressing force is set so that each measured and calculated value approximates the optimum value of the fuzzy variable. A computer for fuzzy inference and each control for comparing each reference value with each operation value and controlling the pulverized material supply amount or the water spray amount in the mill or the crushing roller pressing force so that each operation value becomes equal to each operation value It consisted of a vessel and.

[Action]

When the physical properties of the feed such as crushability change, the amount of bite into the crush roller changes, and the layer thickness on the table changes.
Along with this, the overflow flow rate from the table changes, and the particle size composition of the overflow flow rate also changes. Therefore, the amount conveyed to the mill suction gas and the amount not conveyed are discharged from the lower part of the mill and transported to the circulation BE. The amount changes. That is, the differential pressure and the circulating BE electric power value change due to the change of the ventilation resistance value in the mill.

Furthermore, the amount of crushing roller biting, that is, the amount of crushing work changes, and the amount of crushing roller lift and the value of vibration of the crushing roller also change with changes in the table drive power value and layer thickness. Therefore, by measuring the grinding roller or mill vibration value, mill differential pressure, table drive power value and circulating BE power value, and controlling the amount of crushed material supplied to the mill so that each measured value falls within a certain range. The layer thickness of the pulverized material on the table can be made constant, and the pulverized state of the mill can be stabilized.

The vibration value of the crushing roller may be changed to the vibration value of each installed roller, and the vibration value of the mill body transmitted through the roller may be measured.

The mill suction gas sucks the kiln exhaust gas as shown in FIG. 5, and the suction gas amount also changes when the mill outlet gas temperature changes. Factors that change the mill outlet gas temperature include changes in the mill inlet gas temperature and the water content of the pulverized material. When the mill inlet gas temperature changes, the dry condition of the pulverized material on the table changes, and the layer thickness on the table and the mill outlet gas temperature change. When the water content of the pulverized product changes, the layer thickness on the table and the mill outlet gas temperature also change. Therefore, the mill outlet / inlet gas temperature, the mill outlet gas temperature change rate, and the vibration value of the crushing roller due to the fluctuation of the layer thickness are measured or calculated, and the mill outlet gas temperature is kept constant by bringing these values close to the optimum values. Can be That is, by keeping the mill outlet gas temperature constant, the mill internal circulation amount and the mill suction gas amount can be stabilized, and the water content of the pulverized material can be made constant, and the amount of biting into the pulverizing roller can be stabilized. You can

As for the table drive power value, when the pressing force of the crushing roller is constant, if the crushability of the crushed material on the table becomes poor, the bite on the crushing roller becomes poor and the layer thickness on the table changes and the crushing work decreases. Therefore, the power value for driving the table decreases, and the power value increases as the crushability improves. Therefore, the pressing value of the crushing roller is changed so as to keep the layer thickness on the table constant, and the lift amount of the roller is constant. By keeping the above value and stabilizing the driving power value of the table, the power consumption of the mill can be minimized, that is, the crushing capacity can be maximized.

As described above, when the physical properties of the pulverized product, the gas temperature, etc. fluctuate, the oscillating value of the pulverizing roller or the mill, the differential pressure of the mill, the table drive power value, the circulating BE power value and its change rate, the mill inlet and outlet gas temperature, the mill The influence of the change rate of the outlet gas temperature and the vibration value of the crushing roller due to the change of the layer thickness is intricately meshed, and these are analyzed from the past data, and the pulverized material supply amount to the mill, the mill outlet temperature and the pulverization By controlling the roller pressing values so as to maintain the reference values obtained by fuzzy reasoning, the mill operating conditions can be stabilized and the mill crushing capability can be maximized.

At this time, the value input in advance as a set value to the fuzzy computer is a value obtained by analyzing past operation data.

The transportation amount of the circulating BE can be obtained by previously investigating the relationship between the driving power value of the BE and the transportation amount and inputting this result into the computer.

As for the rate of change in BE power value and mill outlet gas temperature, the amount of change in BE power value and mill outlet gas temperature per unit time is calculated, and the result is output to a fuzzy computer. When the value changes in a short cycle, such as the roller lift amount, the table drive power value, and the roller or mill vibration value, the rate of change is smoothed (first-order delay calculation) and input to the fuzzy computer.

Next, an example of fuzzy inference will be described with reference to FIG. Fig. 3 (a) uses the circulating BE transport rate (CBL), mill power (MLO), and vibration value of the mill body (VIB) as input variables, and the motor rotation speed (FRS) of the constant quantity supply device. And)
This is an example of the case where the changed value of is output. Each graph is individually
Shows membership functions for CBL, MLO, VIB, and FRS. First, the meanings of the fuzzy variables used in FIG. 3 are as follows.

SA (small) Small SM (small medium) A little small MM (medium) Normal ML (medium large) A little large LA (large) Large ST (smaller than) ~ smaller GT (greater than) ~ larger NB (negative big) Negative and large NM (negative medium) Negative and medium NS (negative small) Negative and small ZE (zero) Zero PS (positive small) Positive and small PM (positive medium) Positive and medium PB (positive big) Positive and large In this example, there are two control rules, which are expressed by the IF to THEN types used in programming languages (for example, BASIC).

3 (b) and 3 (c) are control rules (1), respectively.
And the control rule (2). In other words, regarding control rule (1), if CBU = MM, MLO = MM, VIB = ST, then FRS = ZE.

The operating value at this time is CBL = 21T / H, MLO = 590kw, VIB = 16μ
m is the grade (0 to 0) for each operating value.
1) is obtained from the membership function of FIG. 3 (b).
About CBL, MLO, VIB The minimum grade among the membership function grades (in this case, the CBL membership function in Fig. 3 (b)) is the FRS membership function grade (indicated by the diagonal triangles). ). Similar processing is performed for the control rule (2), and the grade of the membership function of the FRS shown in FIG. 3 (c) is obtained (shown by a diagonal triangle).

Then, as shown in FIG. 3 (d),
The triangulated union of the two diagonal lines in Fig. (C) is obtained, the coordinate position -2 of the bisector of this union area is obtained, and the new set value is obtained by adding this value to the current set value. Desired. This new set value is given to the motor rotation speed PID controller of the constant quantity supply device as the output of the computer.

〔Example〕

Using the control method of the present invention, a pulverized product (cement raw material) was pulverized using a vertical mill having specifications shown in Table 1.

FIG. 1 is a block diagram showing a control method and a control device of the present invention. The ground material (cement raw material) in the storage layer is
A predetermined amount is measured by PM2, supplied onto the table 4 of the mill through a charging chute, and is crushed by being bitten by the crushing roller 5 while being moved to the circumferential edge of the table 4 by the centrifugal force accompanying the rotation of the table 4. And is discharged from the edge of the table to the blow-up portion formed between the outer periphery of the table and the mill body.

Further, hot gas for drying the raw material is introduced into the lower part of the mill body, and the crushed cement raw material is entrained in the gas flow blown upward from the lower part of the table 4 through the blowing part. The coarse powder is conveyed to the classifier 8 and classified into coarse powder and fine powder, the coarse powder falls in the mill and is returned to the table 4, and the fine powder is discharged as a product out of the mill together with hot gas.

On the other hand, the coarse-grained cement raw material that did not ride on the hot gas flow fell below the table 4 and was discharged from the mill body for circulation BE9.
Is transported to a storage layer by means of a program, a predetermined amount is weighed by a program together with a new cement raw material, and returned to the table 4 via a chute.

As shown in Fig. 1, PM (quantitative feeder) is provided in this mill device.
2 speedometer 15, flow meter 16, table drive power meter 17, circulation B
E Power meter 18, Mill inlet gas thermometer 19, Mill outlet gas thermometer 2
0, crushing roller lift amount detector 21, crushing roller rotation speed detector 22, crushing roller pressing oil pressure meter 23, crushing roller vibrometer 24 and mill differential pressure detector 25 are installed. A transmitter (not shown) is attached.

2 (a), (b) and (c) show the pulverized material supply amount,
The flow of each controller 30, 40, 50 of the water spray amount and the crushing roller pressing value and its control system is shown.

(1) Control of pulverized material supply amount The measurement value measured by the vibrometer 24 installed in the mill main body is input to a commercially available programmable controller 30 due to the large swing range, and the LAG in the controller 30 is input. The (first-order lag calculator) is used to perform the first-order lag calculation to smooth the measured value and input it to the fuzzy calculator FLC1.

The table drive power value and the mill differential pressure value are also smoothed by LAG and input to the fuzzy computer FLC1.

The measured value of the driving power value of the circulating BE9 is input to the controller 30,
The transport amount is calculated from the relational expression between the electric power value and the transport amount that has been input to the controller 30 in advance, and the change rate is calculated from the change amount of the input value per unit time, which is input to the fuzzy computer FLC1. Let

The fuzzy computer FLC1 has a fuzzy variable that is smaller or larger than the optimum value of each input value and the optimum value analyzed so that the power value of the circulating BE and the table drive power value are optimized based on the past operation results. A control rule combining the above is input, and the reference value of the supply amount so that each input value measured based on this control rule approximates to the optimum value, that is, the reference value of the rotation speed of the variable speed motor 26 of the feeder. The value is fuzzy inferred and the result is output to the controller 30. In the controller 30, the PID calculation is performed so that the deviation between the reference value and the variable speed motor rotation speed becomes zero, and the rotation speed of the variable speed motor 26 is controlled.

(2) Controlling the amount of water sprinkled in the mill Input the mill vibration value and the mill inlet / outlet temperature to the controller 40,
The mill vibration value smoothed by LAG, the rate of change of the mill inlet / outlet temperature, and the mill outlet gas temperature are input to the fuzzy calculator FLC2 as input variables, and the mill outlet gas temperature is previously input to FLC2. Based on the optimum value of each measured value analyzed to be the optimum value and a fuzzy variable that is smaller or larger than the optimum value and the control rule that combines these variables, the mill outlet gas temperature should be close to the optimum value. The result of fuzzy inference is output to the controller 40 as a reference value of the water spray amount in the mill. The PID calculation is performed so that the deviation between the reference value output from the controller 40 and the water spray amount becomes zero, and the water spray amount control valve 27 is controlled.

(3) Control of oil pressure of crushing roller After inputting mill vibration value, table driving power value, crushing roller lift value and roller rotation number to each LAG of the controller 50, after smoothing each measured value , Optimum value and optimum value of each measured value that was input to the fuzzy calculator FLC3 and analyzed so that the crushing roller lift amount and table drive power value become optimum values based on the past operation record that was input in advance to the FLC3 Based on a fuzzy variable that is smaller or larger than that and a control rule that combines these variables, a reference value of the crushing roller pressing pressure obtained by fuzzy inference is output to the controller 50. The controller 50 performs the PID calculation so that the deviation between the reference value and the hydraulic pressure value becomes zero, and adjusts the opening degree of the hydraulic pressure relief valve 28.

For comparison, the operating condition is 88 μm for milling (product).
The operation results with and without the present invention, with the residual amount of 10%, show stable operation results as shown in FIG. 4, and the electric power consumption rate is also the conventional control method as shown in Table 2. It was possible to reduce by 6 to 8% compared to the above.

In the present invention, a general-purpose fuzzy controller manufactured by Fuji Electric is used as the fuzzy computer.

[Effects of the Invention] The present invention was confirmed to have the following excellent effects.

It became possible to quickly respond to changes in the physical properties of the pulverized product and changes in the pulverization conditions such as changes in the temperature of the gas introduced into the mill, thus stabilizing the mill operating conditions. In particular, when crushing a cement raw material, due to a sudden change in pulverizability due to so-called raw material breakage of clay, which is one of the raw materials, and because a kiln-based exhaust gas is sucked as a heat source for drying the mill, By adopting the present invention, it is possible to automatically cope with instantaneous fluctuations in gas flow rate.

In addition, by stabilizing the operation, the mill's crushing capacity can be maximized, and the unit power consumption of the mill is reduced.
The burden on the operator has been reduced and it has become possible to save labor.

[Brief description of drawings]

FIG. 1 is a block diagram showing a control method and control device of the present invention, and FIGS. 2 (a), (b), and (c) are control systems for pulverized material supply amount, water spray amount, and pulverizing roller pressing value, respectively. FIG. 3 is a diagram for explaining the operation of the present invention, showing a method of an example of fuzzy reasoning, FIG. 4 is a trend graph showing the operating conditions of the present invention and a conventional example, and FIG. 5 is an explanatory diagram of the conventional example. Is. 2 …… Fixed amount supply device (PM) 9 …… Circulation BE (bucket elevator) 10 …… Mill differential pressure detector 11 …… Gas thermometer 12 …… Sprinkling controller 13 …… Mill suction fan 15 …… Tachometer 16 …… Flowmeter 17 …… Power meter 18 …… BE Power meter 19 …… Inlet gas thermometer 20 …… Outlet gas thermometer 21 …… Lift amount detector 22 …… Rotation speed detector 23 …… Roller pushing hydraulic pressure Total 24 …… Roller vibrometer 25 …… Mill differential pressure detector 26 …… Variable speed motor 27 …… Control valve 28 …… Relief valve 30, 40, 50 …… Controller LAG …… First-order delay calculator FLC1, 2, 3 ... Fuzzy calculator

Claims (4)

[Claims] In a vertical mill control method, a fuzzy method based on a fuzzy theory of vibration values of a crushing roller or a mill body, table driving power values, circulating bucket elevator power values and their change rates, and mill differential pressure values. Variables and control rules in which the variables are combined are set in advance, and each of the vibration value of the crushing roller or the mill body, the table drive power value, the power value of the circulating bucket elevator and its change rate, and the mill differential pressure are measured. Then, the reference value of the pulverized material supply amount is obtained by fuzzy inference so that each value is approximate to each optimal value of the fuzzy variable according to the control rule, and the pulverized material supply is made equal to the reference value. A method for controlling a vertical mill characterized by controlling the amount. 2. A vertical mill control method comprising a fuzzy variable based on a fuzzy theory of vibration values of a crushing roller or a mill body, a change rate of a mill inlet gas temperature, a mill exit gas temperature, and a change rate thereof. A control rule that combines variables is set in advance, and the vibration value of the crushing roller or the mill main body, the change rate of the mill inlet gas temperature, the mill outlet gas temperature and the change rate are obtained by measurement. According to the control rule, the reference value of the water spray amount in the mill is calculated by fuzzy inference so as to approximate each optimum value of the fuzzy variables, and the water spray amount in the mill is controlled to be equal to the reference value. Vertical mill control method. 3. A vertical mill control method, comprising a fuzzy variable based on a fuzzy theory for each value of a vibration value of a crushing roller or a mill body, a table driving electric power value, a crushing roller lift amount and / or a crushing roller rotation speed, and A control rule combining variables is set in advance, and the vibration value of the crushing roller or the mill body, the table driving power value, the crushing roller lift amount and / or the crushing roller rotation speed are measured, and each measured value is the above-mentioned value. According to a control rule, a reference value of the crushing roller pressing force is calculated by fuzzy inference so as to approximate each optimum value of the fuzzy variables, and the crushing roller pressing force is controlled so as to be equal to the reference value. Vertical mill control method. 4. A vibration value of a crushing roller or a mill body, a table driving power value, a mill differential pressure value, a mill inlet / outlet gas temperature, a power value of a circulating bucket elevator, a crushing roller lift amount and / or a crushing roller rotation speed. And a fuzzy variable based on the fuzzy theory of each of the values set in advance and calculating the respective change rates from the mill outlet gas temperature and the power value of the circulation bucket elevator, and a control rule combining the variables, A computer that fuzzy infers a reference value of the pulverized material supply amount or the water spray amount in the mill or the crushing roller pressing force from each measured value and calculated value so that each measured and calculated value approximates the optimum value of the fuzzy variable. , Each control value is compared with each operation value, and each control for controlling the pulverized material supply amount, the water spray amount in the mill, or the crushing roller pressing force so that each operation value becomes equal to each reference value. Controller of the vertical mill, characterized in that it consists of a vessel.