JPH0830966B2 - Reactor internal temperature control method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a reactor internal temperature control method for predicting and controlling the internal temperature of a reactor this time based on operation data at the time of the last batch operation.

[Prior Art] Conventionally, in reaction temperature control in a batch reactor, which is repeatedly controlled according to a set pattern,
Prevents overshoot during temperature rise, raises temperature in the shortest time,
Stability at regular times is a key point in control, and in particular, overshoot at the time of temperature rise that causes uneven quality and abnormal reactions was the most important point that must be prevented. .

On the other hand, the temperature control of the batch polymerization reactor has been performed by a program setting device for instructing a target temperature rising / falling pattern, a master controller for the internal temperature of the reactor, and a cascade type feedback control for adjusting by the jacket temperature.

That is, as shown in FIG. 4, a temperature control jacket 2 is provided around the reactor 1, and a thermometer 21 for detecting the internal temperature of the reactor 1 is provided. , A signal based on the difference from the set temperature from the setter 22 is output as a set temperature from the controller 23 to the external temperature controller 25, and the temperature at which the temperature of the jacket 2 is detected by the external temperature controller 25 The set temperature is corrected according to the detected temperature from the total 24, and a control signal corresponding to the correction result is output to the control valves 26a and 26b to adjust the amounts of steam and cooling water. The internal temperature was controlled by controlling.

In this case, since PID control alone cannot provide sufficient control, it is necessary to switch from heating to forced cooling as the polymerization reaction progresses. Therefore, the control valve 26 for the steam supplied to the jacket 2 is opened to rapidly heat and raise the temperature of the reactor 1.
This is done by lowering the output of the controller 23 to lower the temperature by the bias set value at the stage when the internal temperature reaches the operation output upper limit set value, that is, at the turning point, and then performing PID control.

[Problems to be Solved] In the conventional internal temperature control method for a reactor described above, there is an abnormal time delay of several minutes before changing the jacket temperature to respond, and feedback control is likely to cause overshoot control. Therefore, there is a problem that the jacket temperature fluctuates greatly and phenomena such as overshoot and runaway occur, and the internal temperature of the reactor tends to become unstable.

Therefore, the control is performed by adjusting the changing speed of the jacket temperature or the setting time of the turning point for switching the temperature from heating to cooling based on the experience of the operator. As a result, a long operating experience is required to determine the turning point, the quality of the control varies depending on the skill level of the operator, and the controllability becomes extremely poor for an unskilled operator.
There is a problem in that the higher the number of products, the stronger the tendency of, the decrease in activity due to the difference in catalyst rods, and the inability to cope with changes in process characteristics due to a decrease in heat transfer due to contamination on the inner surface of the reactor. Was there.

The present invention has been made in view of the above problems,
For example, in a batch polymerization reactor, etc., it is possible to automatically determine a turning point without requiring long operating experience, and also to adapt to process changes so that the internal temperature of the reactor can be controlled. For the purpose of providing.

[Means for Solving Problems] In order to achieve the above object, the method for controlling the internal temperature of a reactor according to the present invention is a method for controlling the internal temperature of a reactor by a jacket temperature. Based on the operating data of the temperature and the jacket temperature, the dynamic characteristic model of the reactor internal temperature and the jacket temperature is estimated by the sequential maximum likelihood estimation method, and then the reactor internal temperature is estimated based on the dynamic characteristic model. This is a control method in which a jacket temperature pattern for matching the internal temperature target pattern is obtained, and this jacket temperature pattern is input to the controller as an initial value to control the jacket temperature.

[Examples] Examples in which the present invention is applied to control of a batch polymerization reactor will be described below.

The method of this embodiment will be described in detail with reference to FIGS. 1 to 4.

FIG. 1 shows an example of a device configuration for carrying out the method of this embodiment.

In FIG. 1, reference numeral 1 is a reactor, and a jacket 2 for controlling the internal temperature of the reactor is provided around the reactor.
A heating or cooling medium supply pipe 3 is supplied to the jacket 2, and heat is exchanged with heating steam or cooling water in the heat exchanger 4 to control the temperature. Reference numerals 5a and 5b are flow rate control valves for temperature control, which are provided in a supply pipe of heating steam or cooling water. 6 is a thermometer for detecting the internal temperature of the reactor 1, 7
Is a thermometer for detecting the temperature of the jacket 2, and 8 is a thermometer for detecting the temperature of the heating or cooling medium.

Reference numeral 10 denotes an arithmetic processing unit, which inputs operating data of the reactor internal temperature and jacket temperature in the previous batch operation via thermometers 6 and 7, and successively calculates model equations relating to the dynamic characteristics of the reactor internal temperature and jacket temperature. Estimate using the maximum likelihood estimation method.
Then, the jacket temperature pattern is obtained based on this dynamic characteristic model, and is set as the initial value of the batch operation to be performed this time.
Output to PID controller 11. The PID controller 11 includes an arithmetic processing unit 10
The control valves 5a and 5b are opened and closed based on the output from the control unit, and the PID control is performed on the difference between the output (dynamic characteristic model) and the actual value.

Next, the flowchart of FIG. 2 and FIG.
The method of controlling the batch polymerization reactor will be described with reference to the temperature curve graph of (b).

The operation data of the reactor internal temperature T _R and the jacket temperature T _J of only the PID control during the first batch operation were measured with the thermometer 6,7.
Input to the arithmetic processing unit 10 via the time series data {T
Save as _R (k), T _J (k)} k = 1 ... l (20
1).

When the operation data at this time is expressed as a temperature curve graph, a graph as shown in FIG.

Based on the above operating data, a dynamic characteristic model of the reactor internal temperature and the jacket temperature is obtained (202).

Reactor internal temperature when jacket temperature T _J is changed
It is assumed that the change of T _R is an ARX (autoregressive input / output) model T _R (k + 1) = T _R (k) + T _J (k) of a linear difference model.

Then, the operation data {T _R (k), T _J (k)} k
= 1 ... L data is used to determine the parameters by the sequential maximum likelihood estimation method, and the dynamic characteristic model is estimated.

The jacket temperature T _J ^* (k) for the reactor internal temperature T _R (k + 1) to match the reactor internal temperature target pattern T _SP (k + 1) is Find more.

The pattern of the jacket temperature T _J ^* (K) thus obtained is stored (204).

The pattern of the jacket temperature T _J ^* (K) is output to the PID controller 11 as an initial value (target pattern), and the current batch operation is performed (205). The target pattern T _J ^* (k) and the actual deviation are controlled by the PID controller 11.

When the operation data at this time is expressed as a temperature curve graph, a graph as shown in FIG. 3 (b) is obtained.

Input the operation data of the reactor internal temperature T _R and jacket temperature T _J in this batch operation to the arithmetic processing unit 10,
The time series data {T _R (k), T _J (k)} is saved as k = 1 ... 1 (206), and the above steps 1 to 3 are repeated.

When the batch polymerization reactor is controlled in this way,
It becomes possible to determine an appropriate turning point based on one or two batch operations, and it is possible to prevent overshoot during temperature rise, temperature rise in the shortest time, and stability during steady state. In addition, this makes it possible to easily cope with batch polymerization reactions of many kinds and automatically cope with changes in process characteristics.

[Effects of the Invention] As described above, according to the method of the present invention, it is possible to easily and optimally control the internal temperature of a reactor that is repeatedly controlled according to a set pattern.

[Brief description of drawings]

FIG. 1 is a block diagram of an apparatus for carrying out the method of one embodiment of the present invention, FIG. 2 is a flow chart of the method of this embodiment, and FIGS. 3 (a) and 3 (b) adopt the method of this embodiment. FIG. 4 is a diagram showing operating data before and after adoption as a temperature curve graph, and FIG. 4 is a block diagram of an apparatus for carrying out the conventional method. 1: Reactor 2: Heater (jacket) 6,7,8: Thermometer 10: Arithmetic processing unit 11: PID controller

Claims (1)

[Claims] 1. A method of controlling the internal temperature of a reactor by a jacket temperature, wherein the dynamic characteristics of the internal temperature of the reactor and the jacket temperature are based on the operating data of the internal temperature of the reactor and the jacket temperature during the previous batch operation. The model is estimated by the iterative maximum likelihood estimation method, and then a jacket temperature pattern for the reactor internal temperature to match the reactor internal temperature target pattern is obtained based on the dynamic characteristic model. The internal temperature control method of the reactor is characterized in that the temperature of the jacket is controlled by inputting it to the controller.