JPH0364798B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention provides an instrumentation control facility equipped with an operating end capable of automatically controlling a kiln, a state detector that automatically detects the state of the kiln, and a calculation function. The present invention relates to a kiln control method for controlling a kiln in combination with a computer having the following.

[Conventional technology]

Conventionally, this type of kiln control method used only stable control captured by an autoregressive model to control the kiln under normal conditions, and when the control limit was exceeded, the computer was disconnected and only the instrumentation equipment was controlled. The kiln was generally controlled by relying on the operator's experience and intuition.

[Problem that the invention seeks to solve]

However, in the conventional kiln control method described above, the stable control area expressed by the autoregressive model is limited, so if disturbance occurs in the kiln and the unstable state continues, the stable control area may be exceeded. In such cases, control by instrumentation equipment alone is used to deal with the situation.Moreover, these two types of control are highly independent of each other, and there is little complementarity between them.The operator's experience and intuition are used to make transitions between the two types of control. Therefore, there was a problem that required skilled operations such as selecting multiple control devices from among dozens of instrumentation devices and transferring control mode from remote to local or vice versa. .

In addition, when the range of stable control is exceeded, it immediately switches to instrumentation control, so even though computer control may continue for a long time, control is performed with emphasis only on safety. Another problem was that economic efficiency such as energy saving and labor saving was often sacrificed.

Therefore, the present invention was made by focusing on the problems of the above-mentioned conventional method.In addition to stable control that employs an autoregressive model, recovery control that applies fuzzy logical control and unstable control due to disturbances etc. The object of the present invention is to provide a kiln control method that enables control of a wider range of kiln fluctuations and stable continuation of control for a longer period of time by combining the control with correction control that corrects the kiln.

[Means for solving problems]

To achieve the above object, the present invention provides a kiln control method for controlling instrumentation control equipment of a kiln using a computer control device, in which a detected value of a state detector for detecting the state of the kiln is within a predetermined limited range. When in a certain steady state, stability control is executed to perform kiln control according to an autoregressive model, and when the stable state exceeds the limited range of the stability control, fuzzy control is performed based on the detected value of the state detector. Recovery control is performed to return to the stable control by performing logical logical control, and even if the stability control or regression control cannot be used due to disturbance of the kiln, the computer control device and the instrumentation control equipment can be connected to each other. The present invention is characterized in that correction control is executed to maintain the linked state and enable external operation of the computer control device.

[Effect]

The specific operation of this invention will be explained using a cement kiln as an example. In other words, when the cement kiln is operating under normal conditions, that is, when the influence of disturbance is small and the fluctuation of measured values at a predetermined measurement point is within a predetermined limited range, stable control using an autoregressive model is performed to control the clinker. equalizes the combustion process.

In addition, if an abnormal condition occurs such as a bank falling in the cement kiln or a clogging in the suspension preheater, and the stability control described above cannot control the situation, recovery control using fuzzy logic control is automatically applied. Control is performed to eliminate the abnormal state by making a temporary transition, and when the state returns to normal, the control is automatically made to transition to stable control.

Furthermore, in response to changes in operating levels, long-term drifts in control variables, and disturbances that cannot be handled by recovery control, corrective control is performed through external operations according to operator guidance information displayed on a CRT display, for example.

Then, each control mode is automatically selected to operate the cement kiln in an optimal state.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a system diagram showing one embodiment of the present invention.

In FIG. 1, 1 is a suspension preheater, 2 is a rotary kiln, and 3 is a clinker cooler.

The suspension preheater 1 has a multi-stage cyclone 1a through which the exhaust gas from the rotary kiln 2 is sucked and supplied by an exhaust fan 4, and powdered cement raw material is transferred to the cyclone 1a at the upper end of the cyclone 1a as a raw material for a belt conveyor, etc. supplied by a supply device 5;
The cement raw material is preheated and pre-calcined by exchanging heat with the kiln exhaust gas.

The rotary kiln 2 is rotatably driven by a kiln driving electric motor 6, and is preheated and heated by the suspension preheater 1 by combustion of fuel supplied to the burner 8 via the fuel supply device 7.
The pre-calcined cement raw material is fired.

The clinker cooler 3 is supplied with a baked ingot (clinker) of a highly basic compound that is a product baked in the rotary kiln 2, and quenches it with cold air and discharges it. The cold air exchanges heat with the clinker in this clinker cooler 3, and the heated secondary air passes through the kiln 2 and piping 9 to the suspension preheater 1.
is supplied to

In the above system, each part is provided with a state detector for detecting its state.

That is, the raw material supply device 5 is provided with an input amount detector 10 consisting of a weight detector and a conveyor rotation speed detector, for example, and an input amount controller 11 for detecting the amount of cement raw material input into the suspension preheater 1. A temperature detector 12 for detecting the temperature of the cyclone raw material is disposed in the suspension preheater 1, and a kiln inlet temperature detector 13 for detecting the kiln inlet temperature is disposed on the inlet side of the rotary kiln 2. ing.

Further, a kiln power detector 14 and a kiln rotation speed detector 15 for detecting the driving power and rotation speed of the kiln drive electric motor 6 of the rotary kiln 2, respectively, and a rotation speed controller for controlling the rotation speed of the kiln drive electric motor 6. 15a are arranged.

Further, the amount of fuel supplied to the burner 8 is detected by a flow rate detector 16, and the flow rate regulator 1
The opening degree of the burner 7 is controlled by a flow rate controller 18, and the burning point temperature at the combustion position of the burner 8 is detected by a temperature detector 19.

Furthermore, the indoor pressure of the clinker cooler 3 is detected by the pressure detector 20.

Detection signals from each of the state detectors are supplied to a computer control device 21, which has a keyboard 22.
A CRT display device 23 is connected, and the computer control device 21 performs predetermined calculations based on the detection signals from each of these detectors to control the firing state of the rotary kiln 2 to an optimum state. In this case, the controlled variables include, for example, the cyclone raw material temperature of the suspension preheater 1, the kiln inlet gas temperature,
There are the burning point temperature, the kiln power, and the clinker cooler 1-chamber pressure, and the operational variables include, for example, the kiln rotation speed, the kiln fuel supply amount, and the kiln raw material input amount.

Here, the computer control device 21 monitors the detection signals from each detector and makes the clinker firing process uniform in response to fluctuations in, for example, raw material composition, kiln inlet raw material temperature, and chemical reactions within the kiln. When the detection signal from each detector is within a predetermined range, the rotary kiln process is treated as a statistical dynamic system, the statistical characteristics are grasped, and the state of rotary kiln 2 is determined based on this. Stability control is performed according to an autoregressive model that quantitatively captures and expresses the mechanism of the causal relationship.

The autoregressive model can be expressed in the following form.

X(k)= _{M 〓} ^{i= 1} A(i) k) is a stationary time series, A(i) is an l×l coefficient matrix, B(i) is an l×m coefficient matrix, M is the order of the autoregressive model, and W(k) is a covariance matrix with mean 0. It is a k-dimensional white noise with Σ.

Then, the above equation (1) is converted into a state space expression, and the optimal control output U(k) that minimizes the quadratic evaluation function is calculated based on the following equation.

U(k)=U(k-1)+ΔU(k)...(3) Here, G is the optimal control gain and Δ is the time difference.

The static control gain G in equation (2) can be calculated by simulation by adjusting the weight matrix of the quadratic evaluation function.
Set the fluctuation range of controlled/manipulated variables to be within the permissible range.

By the way, even during the above-mentioned stable control, the operating level value that should be the target value for stable control may shift due to fluctuations in the raw material composition in the kiln, firing degree, coating, rotational speed, baking point temperature, etc. There is. In response to a state change (drift) during stable operation of the kiln, stable state correction control is performed to change the operating level value and maintain stable control.

Here, changing the operating level value means that even if the target values of the controlled variables and manipulated variables are constant, a stable state may be maintained with the control deviation increasing. It refers to maintaining continued stability by operating to reduce the difference between the level value and the previous value.

That is, when the steady time series is X(k), and the operating level value is taken, the error e(k) is expressed as e(k)=X(k)- (4).

Here, S = | _K 〓 ^i=K0 e(i) | ...(5) It is determined whether S is within the range of operationally acceptable value ε, and when S > ε, , the level value is changed at the discretion of the cement kiln operator.

At this time, if it is desired to maintain the previous operating state, the level value of the controlled variable is changed and control is performed so that S≈0. Here, the value of S is determined by monitoring for a certain period of time T.

On the other hand, when the operator judges that it is desirable to change the previous operating state, he changes both the level value of the manipulated variable and the controlled variable at the same time, and then monitors the situation for a certain period of time and adjusts the level value. Monitor the results of value changes.

Then, when the state of the kiln cannot be stabilized by the above stability control, recovery control is executed.

This recovery control monitors changes in kiln power, which clearly indicate changes in the state of the rotary kiln, determines the magnitude of disturbance that cannot be handled by stability control, takes countermeasures against the disturbance, and monitors the rate of change in kiln power at this time. When a power change exceeding the normal rate of change is detected, it is determined that the coating has fallen inside the kiln, and the magnitude of the coaching fall is determined based on the magnitude of the sudden power rise. Control is performed according to the size, taking into account the moving speed.

In this case, the state inside the kiln changes due to the coaching fall, but it is difficult to clearly distinguish the state of the change based on the size of the fall and the position of the fall. (Fuzzy) behavior and performs fuzzy logic control.

That is, when the coating falls, the kiln power suddenly increases and then gradually decreases, as shown in FIG. 2a. At this time, the kiln burning point temperature gradually decreases over time,
As shown in FIG. 2b, the pressure in one chamber of the clinker cooler 3, as time passes, causes a fuzzy phenomenon in which it reversely rises and returns to its original state after passing the falling coating.

By making a fuzzy logical decision on this, it is possible to carry out control that accelerates the recovery of the rotary kiln 2 to a steady state by appropriate operation control that matches the phenomenon.

Specifically, changes in kiln power are monitored, and it is determined whether the amount of change ΔW per unit time is greater than or equal to a predetermined set value WS, and the determination result is ΔW <
When it is WS, it is determined to be a normal state and the stability control is continued, and when ΔW≧WS, it is determined that a small disturbance has occurred and the stability control is immediately shifted to recovery control.

This recovery control performs control to increase the kiln fuel by a predetermined amount F set in advance.

In this state, the kiln power stabilizes and the wind pressure in one chamber of the clinker cooler 3 increases, and after passing the peak point P, the steady state wind pressure level a is reached at a predetermined pressure ΔP.
When the value returns to within the allowable range, it is determined that the disturbance has recovered.

When it is determined that disturbance recovery has occurred, the kiln fuel is reduced by the predetermined set amount F in order to restore the kiln control system to a stable state, and when the kiln fuel returns to the steady state set value, the recovery control is stabilized. Automatically transition to control.

In addition, the coaching fall was a major disturbance,
If controlling the kiln fuel is not enough, add controls such as slowing down the kiln rotation speed or reducing the amount of raw material fed into the kiln, and wait for the fuzzy recovery of the kiln power, burning point temperature, and clinker cooler 3 chamber pressure. Performs recovery control to return the manipulated variable to its original state.

Furthermore, when the recovery control or the steady state correction control is in a state where it is difficult to return to stable control, the control shifts to correction control.

This correction control is used when a large disturbance that cannot be dealt with by recovery control or steady state correction control occurs.
Guidance information corresponding to the event is sent from the computer control device to the CRT display 23 having the keyboard 22 and displayed on the display screen, requesting the operator to perform an external operation, and the operator selects the keyboard 22 based on the displayed guidance information. is operated to input operation instruction information to the kiln computer control device 21, and the rotary kiln 2 is controlled at a fixed value.

When the condition of the kiln becomes stable through this constant value control, the control mode automatically shifts to stability control according to the control mode transition diagram.

In this way, the modification control uses a computer as a repair control program, instead of separating the computer control and having the operator judge and manually operate the instrumentation only, as in the conventional case. Optimal kiln control can be performed without having to be conscious of switching between remote, automatic, and manual operation of instrumentation control equipment.

FIG. 3 shows a specific processing procedure for selecting the above-mentioned stability control, stable state correction control, recovery control, and correction control.

First, in a step, it is determined whether the kiln is in an unsteady state other than a steady state, and if it is in a steady state, the process moves to a step to perform stability control according to the autoregressive model.

In addition, if the judgment result of the step is an unsteady state, the process moves to the step and executes recovery control that changes the manipulated variables according to the disturbance pattern such as the kiln inlet raw material temperature and clinker cooler 1 chamber pressure, and then returns to the step. to monitor the kiln condition for a certain period of time _T1 .

Next, the process moves to step and it is determined whether the control variable is less than the standard value. Here, if the controlled variable is less than the standard value, the process moves to step to perform a recovery operation of the manipulated variable, and then moves to step to determine whether or not the steady state is reached. If the judgment result of this step is an unsteady state, wait until the predetermined time _T2 has elapsed, then return to the step, repeat the above steps, and move to the step; if the result is a steady state, move to the step. Transition to stability control.

Also, if the judgment result of the step is that the control variable is equal to or higher than the level value, the process moves to the step, and it is judged whether this state has continued twice, and
When it is the second time, go back to the step, and when it is the second time, go to the step and
Performs interactive modification control via CRT display.

As a result of this corrective control, when the kiln reaches a steady state in which no change in set value is required, the kiln shifts to stable control according to the control mode transition diagram.

In the above example, the cyclone raw material temperature,
Although we have explained the case where the kiln inlet gas temperature, burning point temperature, kiln power, and clinker cooler 1 chamber pressure are set as operating variables, the kiln rotation speed, kiln fuel supply amount, and kiln raw material input amount are respectively set, but the present invention is limited to this. However, various controlled variables and manipulated variables can be applied depending on the control mode of the rotary kiln 2 and also to general kilns.

〔Effect of the invention〕

As explained above, according to the present invention, stability control according to an autoregressive model according to the state of the kiln, recovery control that performs fuzzy logic control when a disturbance that cannot be handled by stability control occurs, and When a large turbulence that cannot be dealt with by monostable control or recovery control occurs, corrective control, which performs constant value control in an interactive manner using a CRT display, is selected in response to changes in the kiln condition, so it can be used for long periods of time. This makes it possible to control the amount of free lime (F・CaO), which is one of the important indicators of kiln operation, below a certain percentage, thereby improving the uniformity of clinker quality. can. As a result, the fuel consumption rate is reduced. In addition, stable continuation over a long period of time results in the effect of extending the life of the kiln refractory bricks and increasing annual production.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention, FIG. 2 is a signal waveform diagram for explaining recovery control of the present invention, and FIG. 3 is a flowchart showing an example of a selection procedure for each control mode. In the figure, 1 is a suspension preheater, 2 is a rotary kiln, 3 is a clinker cooler, 5 is a raw material supply device, 6 is a kiln driving electric motor, 8 is a burner,
10 is an input amount detector, 11 is an input amount controller, 14
1 is a kiln power detector, 15 is a kiln rotation speed detector, 15a is a kiln rotation speed controller, 16 is a flow rate detector, 17 is a flow rate regulator, 20 is a pressure detector, 2
1 is a computer control device, 22 is a keyboard, 23 is a
It is a CRT display device.

Claims (1)

[Claims] 1. In a kiln control method in which a computer control device controls instrumentation control equipment of a kiln, the kiln is in a steady state in which a detected value of a state detector that detects the state is within a predetermined limited range. Sometimes, stability control is performed to control the kiln according to an autoregressive model, and when the stabilized state exceeds the limited range of the stability control, fuzzy logic control is performed based on the detected value of the state detector. When the stabilization control or the recovery control cannot deal with the disturbance of the kiln, etc., the computer control device and the instrumentation control device are maintained in an interlocked state and the computer control device is operated. A kiln control method, characterized in that a correction control is executed that allows external operation of a control device. 2. The kiln control method according to claim 1, wherein the correction control includes steady state correction control in which a control deviation in a stable control state based on an autoregressive model is corrected by a level value changing process.