JP4710345B2 - Reactor temperature control method and reactor temperature control apparatus - Google Patents

Description

  The present invention relates to a reactor temperature control method and a reactor temperature control apparatus used in the field of process control such as petrochemistry.

  In the field of process control such as petrochemistry, temperature control of a polymerization reaction process is considered to be one of difficult things to automate. For example, in the case of producing a high-performance polymer, since there are formulations in which a plurality of raw materials are charged at different times, the temperature characteristics of the reactor are different, and appropriate temperature control largely depends on the operator's intuition and experience. In addition, recently, there is a demand for high-mix low-volume production, and it is necessary to carry out several dozens or hundreds of prescriptions in one reactor.

  As a conventional technique, [Non-Patent Document 1] describes a technique that includes a plant model, estimates the thermal efficiency of the reactor and the jacket, and realizes optimal control based on the estimation result. .

  [Patent Document 1] previously measures the overall thermal efficiency of the jacket and the liquid in the tank for a certain time after the start of temperature adjustment, the liquid weight in the tank, the temperatures at the jacket inlet and outlet, and the pump discharge amount. The temperature is determined while determining the pump discharge amount and the temperature of the heat exchange medium to be supplied to the jacket so that the heat transfer amount calculated using the overall heat efficiency becomes a desired value. A method for adjusting the temperature of the jacketed tank to be adjusted is described.

  [Patent Document 2] includes a heat exchange amount calculation means for obtaining a heat exchange amount between the inside and outside of the reactor necessary for setting the temperature in the reactor as a target temperature, and heat exchange. A heat medium supply means for supplying the heat medium almost quantitatively to the outside of the reactor so as to achieve the heat exchange amount calculated by the amount calculation means, a supply temperature setting means for setting the supply temperature of the heat medium, and a heat A batch reactor temperature control device having a supply temperature control means for controlling the temperature of the medium is described.

  Thus, in conventional reactor temperature control, a target temperature corresponding to the product is set, and hot water is usually added to the jacket around the reactor so that the reaction temperature (same as the reactor temperature) matches this target temperature. Alternatively, heating or cooling is performed from outside the reactor through a heat medium such as cold water. For heating or cooling from the outside of the reactor, the set value of the jacket inlet side temperature is obtained by feedback control of the reaction temperature, and the opening of the jacket flow valve and the temperature of the heat medium are adjusted so that these set values are obtained. In general, so-called cascade control is performed.

  [Patent Document 3] includes jacket temperature correction amount calculation means for calculating a jacket temperature correction amount based on the measured reactor temperature value and data from the disturbance database, whether or not the operation procedure control is executed, the reaction A means for determining whether or not jacket temperature correction is necessary based on the measured vessel pressure and reaction temperature, and a correction means for correcting the jacket temperature correction amount when the determination means determines that correction is necessary. A reaction temperature controller is described.

  [Patent Document 4] describes the temperature difference between the reaction liquid temperature detected by the reaction liquid in the reactor and the set value, the cooler outlet temperature detected by the reaction liquid flowing back to the reactor through the cooler, and the set value. And a temperature control device for a reactor that controls a control valve that adjusts a flow rate of a coolant flowing in the cooler based on a temperature difference between the temperature of the reaction solution and a temperature difference between the reaction solution temperature and the cooler outlet temperature Yes.

JP-A-6-266448 Japanese Patent Laid-Open No. 10-296075 JP 2004-283780 A JP-A-6-142490 Thousands of funds, Yuta Hana: Fundamentals and applications of instrumentation systems, pages 517-523, Ohmsha, 1987.9.30

  The conventional technology described in [Patent Document 4] directly measures the temperature of the reaction liquid in the reactor, and has a problem that it cannot be applied unless the reaction liquid is circulated directly to the cooler. Due to the control, the temperature of the reactor has the problem of causing undershoot and hunting.

  In the case of controlling the temperature via the jacket in the reactor temperature control, the temperature is controlled via the jacket, so heat from the outside does not reach the inside of the reactor quickly, and there is heat loss and time delay. In addition, there is a complexity that heat of reaction is generated in the course of the polymerization reaction to raise the temperature inside the reactor.

  As in the prior art described in [Non-Patent Document 1] and [Patent Document 1] to [Patent Document 3], the set value of the inlet temperature of the jacket is obtained by reaction temperature feedback control, and becomes this set value. Thus, in the method of adjusting the opening of the jacket flow valve and the temperature of the heat medium, by adjusting finely the control parameter, for example, the proportional gain and integral gain with respect to the deviation from the target temperature, the delay of temperature adjustment from the outside Even if there is self-heating inside the reactor, the temperature can be controlled to some extent.

  In recent years, however, high-mix low-volume production has been demanded, and the target temperature, the amount of raw material charged, and the charging pattern differ for each prescription. Therefore, it is necessary to individually adjust the control parameters for each prescription. Thus, managing the control parameters for each prescription is a heavy burden and the management cost is enormous. In addition, since it is impossible in practice to perform plant tests for each prescription for adjusting control parameters, representative parameters can be set and manually interpolated during operation. ing.

  In addition, when feedback control is performed, if the gain of control parameters such as integral gain is set to a high value, the reactor temperature control performance may be improved, but it is unstable and cannot be applied to various product prescriptions. Because of the problem, the gain of the control parameter had to be set to a low value with a margin. For this reason, the temperature of the reactor has a problem of causing undershoot and hunting.

  A first object of the present invention is to provide an easy and stable reactor temperature control method and reactor temperature control apparatus that can improve control system stability and disturbance suppression even if the product formulation is different.

  The second object of the present invention is to provide a temperature control method and a reactor temperature control which can be set to increase the sensitivity characteristics of the reactor temperature control system and increase the control responsiveness even if the product formulation is different. To provide an apparatus.

  In order to achieve the above object, the reactor temperature control method and reactor temperature control apparatus of the present invention calculates the jacket temperature set value by inputting the set temperature value of the reactor and the measured value of the reactor temperature. Then, by inputting the measured value of the jacket outlet temperature by the signal generator and giving a negative gain to the jacket outlet temperature, the correction value is calculated, and the jacket temperature setting value corrected by adding the jacket temperature setting value and the correction value The valve opening setting value is calculated by inputting the value and the measured value of the jacket inlet temperature.

According to the present invention, the jacket outlet temperature is fed back, a correction signal that changes in the opposite direction to the change in the jacket outlet temperature is given to the jacket temperature setting value, and the control signal of the temperature control system of the reactor is suitably used. Since the correction is made, the control system stability and disturbance suppression are improved, and the reactor temperature can be controlled easily and stably regardless of the type of product formulation.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of a reactor temperature control apparatus according to the present embodiment, FIG. 2 is a diagram showing operating characteristics of a split range, FIG. 3 is a configuration diagram of a reactor temperature control system to a jacket temperature control system, and FIG. 4 is a flowchart of control of the control system shown in FIG. 3, and FIG. 5 is a diagram showing an example of a control result.

  The reactor temperature control apparatus is configured as shown in FIG. In order to control the temperature of the reactor 10, a jacket 20 is attached to the reactor 10 in which a polymerization reaction or the like is performed inside accompanied with a chemical reaction. A water supply pipe 21 and a drain pipe 22 for supplying water to the jacket 20 are attached to the jacket 20, and a heat medium supplied from the water supply pipe 21 circulates in the jacket 20 and is discharged from the drain pipe 22. ing. Here, the chemical reaction in the reactor 10 may be an exothermic process that generates heat by a chemical reaction or an endothermic process that absorbs heat by a chemical reaction.

  A jacket inlet thermometer 40 is provided on the jacket 20 side of the water supply pipe 21, and a circulation pump 50 is provided on the upstream side of the jacket inlet thermometer 40 of the water supply pipe 21. The upstream side of the circulation pump 50 is branched, a hot water valve 70 is provided in one water supply pipe 21a, a cold water valve 71 is provided in the other water supply pipe 21b, and the hot water valve 70 and the cold water valve 71 are provided in a split range. 80.

  The operating characteristics of the split range 80 are as shown in FIG. The horizontal axis indicates the valve opening setting signal SU, which is an operation signal, and the vertical axis indicates the corresponding valve opening. A valve opening degree of 0% corresponds to full valve closing, and a valve opening degree of 100% corresponds to full valve opening.

  In this example, when the valve opening setting signal SU is 0% to 50%, the opening signal of the chilled water valve 71 is converted to 100 to 0%, and the valve opening setting signal SU is 50 to 100%. When%, the opening signal of the hot water valve 70 is converted to 0 to 100%.

  Also, since the initial equilibrium point of the controller is set to the temperature operation signal SU = 50%, when the reaction temperature is stable and neither heating nor cooling is required from the outside, the temperature operation signal SU = 50% and the hot water valve The cold water valve is also fully closed.

  A thermometer 30 is attached to the reactor 10, and the temperature of the reactor 10 is measured and fed back to the control device 100. The amount of raw material is adjusted and supplied to the reactor 10 by a raw material supply valve (not shown).

  The drain pipe 22 is provided with a jacket outlet thermometer 60 and a bypass pipe 23 connected from the upstream side of the jacket outlet thermometer 60 to the upstream side of the circulation pump 50.

A general-purpose computer is used for the control device 100 that is a control system, and is connected to the prescription database 300. The control device 100 inputs the signal S301 from the prescription database 300 and the signal S31 from the thermometer 30 to generate the jacket temperature setting signal S201 and the signal S61 from the jacket outlet thermometer 60. A signal generation unit 500 that generates a correction signal S501, a signal correction unit 600 that generates a jacket temperature setting signal S601 corrected by the jacket temperature setting signal S201 from the reactor temperature control system 200 and the signal S501 from the signal generation unit 500. The jacket temperature control system 400 generates the valve opening setting signal S401 by inputting the corrected jacket temperature setting signal S601 from the signal correction unit 600 and the signal S41 from the jacket inlet thermometer 40.

  Here, in this embodiment, the reactor temperature control system 200, the signal generation unit 500, the signal correction unit 600, and the jacket temperature control system 400 are configured by software, but a part thereof may be configured by hardware. it can.

  When the prescription of the product to be manufactured is determined, the prescription of the product is input to the control device 100. Based on the input data, the raw material supply valve (not shown) is adjusted with reference to the prescription database 300 to supply the raw material to the reactor 10. The temperature setting value of the reactor calculated corresponding to the input prescription is transmitted to the reactor temperature control system 200 as a signal S301.

  In the reactor temperature control system 200, in step 111 of the flow chart shown in FIG. 4, the deviation E between the reactor temperature setting value Tsp and the reactor temperature Tr (both the target deviation E) is determined from the signals S31 and S301 indicating the reactor temperature. And a proportional-integral type feedback control calculation for performing a proportional-integral calculation with respect to the target deviation in the equation (1).

(Equation 1)
Tjs = K1 * E + K2 * ∫Edt (1)
Here, K1 and K2 are a proportional gain and an integral gain, respectively, and are parameters for adjusting the control performance of the feedback control. Further, although the differential term is not provided in Equation 1, a differential operation may be added. Further, another control calculation such as a calculation using a table is also applicable. It can also be applied to model-based predictive control. In this case, a parameter for adjusting the closed loop sensitivity characteristic of the feedback control system is necessary, but high sensitivity setting is possible.

  As shown in FIG. 3, the jacket temperature setting value Tjs, which is the calculation result obtained by Equation 1, is stored in the storage unit 605 as the jacket temperature setting signal S201 in step 112 shown in FIG. The signal S501 from the signal generation unit 500 is added to the addition unit 606, and the corrected jacket temperature setting signal S601 is stored in the storage unit 607 in step 116.

  In the signal generation unit 500, the signal S61 from the jacket outlet thermometer 60 is input in step 113 to calculate the jacket outlet temperature Tj, and in step 114, the correction value Tjh is calculated by Equation 2 to generate the correction signal S501. .

(Equation 2)
Tjh = −K * Tj (2)
Here, K is a constant gain and 1 ≧ K> 0, but a large numerical value of K> 1 may be used. In Equation 2, the jacket outlet temperature Tjo and the correction value Tjh are calculated so that the changes are in opposite directions, but a dead zone may be provided for the jacket outlet temperature. Further, the signal generation unit 500 may have a lookup table format expressed by Equation 3 as long as a negative gain is given.

(Equation 3)
Correction signal = FUNC (jacket outlet temperature) (3)
Here, FUNC means a function.

  The corrected jacket temperature setting signal S601 is input to the jacket temperature control system 400 in step 117. The jacket temperature control system 400 compares the jacket inlet temperature Tji and calculates the deviation F. A proportional-integral-derivative feedback control calculation that performs proportional-integral-derivative calculation on the deviation F in Equation 4 is performed to calculate the valve opening set value Bs.

(Equation 4)
Bs = K3 * F + K4 * ∫Fdt + K5 * dF / dt (4)
Here, K3, K4, and K5 are a proportional gain, an integral gain, and a differential gain, respectively, and are parameters that adjust the control performance of feedback control. Further, although the proportional integral differential calculation is shown in Equation 4, similar to the reactor temperature control system 200, another control calculation such as a calculation using a table can be applied.

  The valve opening setting value Bs is transmitted to the split range 80 as a valve opening setting signal S401, and is converted into an opening signal of the hot water valve 70 for heating or the cold water valve 71 for cooling in the split range 80. 70 or the cold water valve 71 to control the opening degree of the hot water valve 70 or the cold water valve 71.

  FIG. 5 shows an example in which the reactor temperature control is performed by setting the gains such as the proportional gain, the integral gain, and the differential gain to high values by the reactor temperature control apparatus of this embodiment. The figure shows changes in reactor temperature, jacket outlet temperature, and jacket inlet temperature when the reactor temperature rises due to heat generated by a chemical reaction in the reactor during formulation and acts as a disturbance.

  As can be seen from FIG. 5, when the temperature of the reactor rises, the correction signal S501 is generated by the signal generator 500, so the jacket inlet temperature is lowered. Due to the decrease in the jacket inlet temperature, the rising jacket outlet temperature stops and starts to decrease. As a result, the decrease in the jacket inlet temperature is once mitigated by the effect of the correction signal S501, transitions to the opposite side to the decrease in the jacket outlet temperature, and gradually increases the jacket inlet temperature.

  On the other hand, although the temperature of the reactor starts to decrease, since the decrease in the jacket inlet temperature is suppressed, the undershoot from the set value of the reactor temperature is small.

  As described above, in the control method of the present embodiment, the overshoot or undershoot after suppressing the disturbance of the reactor temperature is small, and as a result, the sensitivity characteristic of the temperature control system of the reactor is increased, and the control responsiveness is increased. Can be set.

  On the other hand, when the signal generation unit 500 that feeds back the jacket outlet temperature is not provided, the jacket inlet temperature continues to decrease as the reactor temperature increases, causing undershoot and hunting. It takes time for the temperature of the vessel to converge to the set value. In order to prevent this, in the control that does not include the signal generation unit 500, it is necessary to set the control parameters such as the proportional gain and the integral gain to a low value so that the control system has low sensitivity. Responsiveness is good because control parameters such as proportional gain and integral gain can be set to high values.

  Another embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a block diagram of the reactor temperature control apparatus of the present embodiment, FIG. 7 is a flowchart of reactor temperature control, and FIG. 8 is a diagram showing a look-up table for calculating a correction signal.

  As shown in FIG. 6, the reactor temperature control device of this embodiment is configured in the same manner as the reactor temperature control device shown in FIG. 1, but in this embodiment, the jacket inlet thermometer 40 and the circulation control device are circulated. A jacket flow meter 90 is provided between the pump 50 and the jacket flow measurement value S91 detected by the jacket flow meter 90 is input to the signal generator 500. Further, similarly to the embodiment shown in FIG. 1, the control is performed along the flow chart of the temperature control of the reactor shown in FIG.

  In this embodiment, the case where the circulation pump 50 is stopped or the case where the rotational speed of the circulation pump 50 is changed and the flow rate of the heat medium circulating in the jacket 20 is changed is considered.

  The signal generation unit 500 inputs the signal S61 from the jacket outlet thermometer 60 and the jacket flow rate measurement value S91 detected by the jacket flow meter 90, and outputs an appropriate correction signal in response to a change in the jacket flow rate. calculate. In the present embodiment, when the flow rate of the heat medium increases, the correction signal is calculated so as to increase the correction coefficient.

  This correction signal is calculated using a lookup table shown in FIG. In the example shown in FIG. 8, the correction signal corresponding to the jacket outlet temperature and the jacket flow rate is shown, and the signal generator 500 is provided with this lookup table, and the jacket outlet temperature and the jacket flow rate are inputted to correspond. The correction signal to be output is output. Note that the signal generation unit 500 may be in a function format, and calculates a correction signal using Equation 5, in which case xn and yn shown in FIG. 7 are arguments.

(Equation 5)
zn = FUNC (xn, yn) (5)
Thus, since the correction signal is calculated by feeding back the flow rate of the heat medium, the sensitivity characteristic of the reactor temperature control system can be increased and the control responsiveness can be increased when the flow rate increases.

  According to the present embodiment, in the temperature control of the reactor, the correction signal that changes in the opposite direction to the change in the jacket outlet temperature is given to the jacket temperature set value, so that the quick response and stability of the jacket temperature control system As a result, the closed loop characteristics of the entire reactor control system can be set with high sensitivity.

It is a block diagram of the reactor temperature control apparatus which is one Example of this invention. It is a figure which shows the operating characteristic of a split range. It is a block diagram of the calculating part of a present Example. It is a flowchart of the temperature control of the reactor of a present Example. It is a figure which shows an example of the time change of reactor temperature, jacket outlet temperature, and jacket inlet temperature. It is a block diagram of the temperature control apparatus of the reactor which is another Example of this invention. It is a flowchart of the temperature control of the reactor of a present Example. It is a figure which shows the example of the table with which the signal generation part of a present Example is equipped.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Reactor, 20 ... Jacket, 30 ... Thermometer, 40 ... Jacket inlet thermometer, 50 ... Circulation pump, 60 ... Jacket outlet thermometer, 70 ... Valve (70H = hot water, 70C = cold water), 80 ... Split range 90 ... Jacket flow meter, 100 ... Control device, 200 ... Reactor temperature control system, 300 ... Prescription database, 400 ... Jacket temperature control system.

Claims (5)

Input the set temperature value of the reactor and the measured temperature value of the reactor calculated in accordance with the input recipe, calculate the jacket temperature set value, and input the measured value of the jacket outlet temperature by the signal generator. the jacket calculates a correction value so as to change a direction opposite of the outlet temperature, the jacket temperature set value and the correction value and inputs a measured value of the jacket temperature set value and the jacket inlet temperature is corrected by adding Te Calculating a valve opening setting value of a hot water valve or a cold water valve provided in a water supply pipe to the jacket, and controlling the valve opening degree of the hot water valve or the cold water valve by the valve opening setting value, A reactor temperature control method for controlling the temperature of a heat medium circulating in a jacket . The heat medium is circulated through a jacket having a water supply pipe and a drain pipe by a circulation pump, and the opening degree of a hot water valve or a cold water valve provided on the upstream side connected to the water supply pipe by a split range is controlled, and the raw material of the prescription Is a reactor temperature control method for controlling the temperature of a reactor to which a reactor is supplied, wherein a control device controls a set temperature value of the reactor, a measured value of the reactor temperature, a measured value of the jacket outlet temperature, and a jacket. enter the measured value of the outlet temperature and outputs the valve opening set signal to said split range, the valve open by adding the correction value to be changed in the opposite direction of the jacket outlet temperature from the measured value of the jacket outlet temperature Reactor temperature control method for calculating degree setting signal. The jacket temperature set value is calculated by inputting the set temperature value of the reactor and the measured value of the reactor temperature, and the measured value of the jacket outlet temperature is input by the signal generator to reverse the change of the jacket outlet temperature. The correction value is calculated so that the jacket temperature setting value and the correction value are added to obtain the corrected jacket temperature setting value and the measured value of the jacket inlet temperature, and are provided in the water supply pipe to the jacket. anti応器temperature control method for calculating a valve opening setting value of hot valve or cold water valve which is.   A temperature control method for a reactor in which a heat medium is circulated through a jacket and the temperature of the reactor is adjusted to a preset temperature of the reactor by heat exchange between the jacket and the reactor. A jacket temperature setting value is calculated by inputting a temperature measurement value, and a correction value is calculated so as to be opposite to the change in the jacket outlet temperature by inputting a measurement value of the jacket outlet temperature by the signal generator, The corrected jacket temperature set value is calculated by adding the jacket temperature set value and the corrected value, and the hot water valve provided in the water supply pipe to the jacket is calculated from the corrected jacket temperature set value and the measured value of the jacket inlet temperature. Alternatively, the temperature control of a reactor that controls the temperature of the heat medium that circulates the jacket by calculating the valve opening setting value of the cold water valve and controlling the valve opening by the valve opening setting. Method. 4. The jacket flow rate measurement value is input to the signal generation unit, and when the jacket flow rate measurement value is increased, the correction value is increased so as to increase the correction value. The method for controlling the temperature of the reactor according to claim 1.

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