Temperature control in chemical reactors with slow response of the cooling system; Definition of coefficients of control safety

1983 ◽  
Vol 48 (3) ◽  
pp. 711-721 ◽  
Author(s):  
Josef Horák ◽  
František Jiráček
Keyword(s):  
Temperature Control ◽  
Cooling System ◽  
Operating Temperature ◽  
Batch Reactor ◽  
Exothermic Reaction ◽  
Chemical Reactor ◽  
Loop Control ◽  
Information Safety ◽  
Definition Of ◽  
Reactor Operating

Coefficients of static, dynamic and information safety are defined. They cold be used for consideration of how difficult is the feedback of temperature control in a chemical reactor with exothermic reaction. An analysis is made for a batch reactor which should be kept in a pseudostationary state which is unstable at the open control loop. Control is based on measurement of the reaction mixture temperature and on evaluation of temperature derivative with time. The action quantity is flow rate of the carrier in the cooling system. The result of an analysis is the highest operating temperature of the mixture at which the safety of the reactor operation is still secured and further the trajectory on which it is possible to reach in the shortest time the given operating temperature at preserving safety of the reactor operating.

A feedback temperature control in a chemical reactor with high inertia of its cooling system

1984 ◽  
Vol 49 (7) ◽  
pp. 1642-1652 ◽  
Author(s):  
Josef Horák ◽  
František Jiráček ◽  
Libuše Ježová
Keyword(s):  
Mathematical Model ◽  
Temperature Control ◽  
Cooling System ◽  
Batch Reactor ◽  
Time Derivative ◽  
Exothermic Reaction ◽  
Chemical Reactor ◽  
The One ◽  
The Mathematical Model ◽  
The Given

In this work we compare simple algorithms for the one-off feedback temperature control of the reaction mixture in a batch reactor during an exothermic reaction. The aim of the control was to maintain the temperature of the mixture within the given range, and simultaneously, to minimize the number of the regulator switchings. The temperature control of the mixture was being performed at conditions when working states of the reactor in an open regulation loop are unstable and when the response of the cooler to regulation is slow. The following control algorithms were compared: P - regulator, PD - regulator and algorithms based on a prediction mathematical model including its adaptive variant. The results indicate that the algorithms based on the mathematical model are more efficient. However, the precision of the control can be diminished due to error in the time derivative of the temperature of the reaction mixture which forms the input to the prediction model. The adaptive variant of the algorithms was advantageous in cases when it was necessary to make up for significant errors in initial estimates of parameters of the prediction mathematical model.

A simplified method of temperature control maximizing productivity of the batch reactor; The effect of inertia of the cooling system

1982 ◽  
Vol 47 (2) ◽  
pp. 454-464 ◽  
Author(s):  
František Jiráček ◽  
Josef Horák
Keyword(s):  
Mathematical Model ◽  
Temperature Control ◽  
Cooling System ◽  
Batch Reactor ◽  
Exothermic Reaction ◽  
Cooling Capacity ◽  
Variable Activity ◽  
Simplified Method ◽  
Opening And Closing ◽  
Time Of Operation

The effect has been studied of the inertia of the cooling system on the reliability of control of the temperature of the reaction mixture. The study has been made using a mathematical model of the batch reactor with an exothermic reaction. The temperature has been controlled by a two-level controller opening and closing the flow of the coolant. The aim of the control has been to maintain a constant value of the degree of utilization of the cooling capacity of the reactor. The instantaneous value of the degree of utilization has been assessed from the ratio of times for which the cooling system is idle to the time of operation. The reliability of control has been studied for variable activity of the catalyst.

scholarly journals Methodology of Supervision by Analysis of Thermal Flux for Thermal Conduction of a Batch Chemical Reactor Equipped with a Monofluid Heating/Cooling System

2012 ◽  
Vol 2012 ◽  
pp. 1-10
Author(s):  
Ghania Henini ◽  
Fatiha Souahi ◽  
Ykhlef Laidani
Keyword(s):  
Thermal Conduction ◽  
Cooling System ◽  
Batch Reactor ◽  
Thermal Flux ◽  
Exothermic Reaction ◽  
Chemical Reactor ◽  
Thermal Control ◽  
Ride Quality ◽  
Heating And Cooling

We present the thermal behavior of a batch reactor to jacket equipped with a monofluid heating/cooling system. Heating and cooling are provided respectively by an electrical resistance and two plate heat exchangers. The control of the temperature of the reaction is based on the supervision system. This strategy of management of the thermal devices is based on the usage of the thermal flux as manipulated variable. The modulation of the monofluid temperature by acting on the heating power or on the opening degrees of an air-to-open valve that delivers the monofluid to heat exchanger. The study shows that the application of this method for the conduct of the pilot reactor gives good results in simulation and that taking into account the dynamics of the various apparatuses greatly improves ride quality of conduct. In addition thermal control of an exothermic reaction (mononitration) shows that the consideration of heat generated in the model representation improve the results by elimination any overshooting of the set-point temperature.

A two-point regulator control of a chemical reactor; Cooling system with a large inertia - PD algorithm

1983 ◽  
Vol 48 (9) ◽  
pp. 2627-2635 ◽  
Author(s):  
Josef Horák ◽  
František Jiráček ◽  
Libuše Ježová
Keyword(s):  
Temperature Control ◽  
Cooling System ◽  
Batch Reactor ◽  
Chemical Reactor ◽  
Slow Response ◽  
Practical Utilization ◽  
Laboratory Scale Reactor ◽  
Combined Simulation ◽  
Rate Of Response

The effect has been investigated of the gain of the derivative element of a PD controller on the quality of the temperature control of an exothermal reaction mixture in a batch reactor. The investigation concerned a reactor equipped with a cooling system whose rate of response could be varied in the range of several orders of magnitude. The results have lead to the conclusion that a slow response of the coolong system is difficult to make up for by using more sophisticated control algorithms. For the slow response of the cooling system the range of gain of the controller providing for a safe temperature control is narrow leaving essentially no margin for its practical utilization. The study combined simulation on a mathematical model with experimental verification of a laboratory scale reactor cooled by a submersible retractable cooler.

Temperature control in a chemical reactor through variable area of the heat transfer surface. Experimental verification

1982 ◽  
Vol 47 (2) ◽  
pp. 446-453
Author(s):  
Josef Horák ◽  
František Jiráček ◽  
Libuše Ježová
Keyword(s):  
Batch Reactor ◽  
Exothermic Reaction ◽  
Chemical Reactor ◽  
Open Loop ◽  
Heat Transfer Surface ◽  
Laboratory Reactor ◽  
Hysteresis Control ◽  
Relay With Hysteresis ◽  
Rate Of Response ◽  
The Ideal

A possibility has been tested in the paper of the feed back control of temperature of the reaction mixture in a batch reactor with an exothermic reaction through the variable area of the cooling surface. The measurement were carried out in a laboratory reactor with a retractable cooler which was being immersed into the reaction mixture. The speed of motion of the cooler was sufficiently high permitting the process of immersion to be regarded as practically instantaneous. The aim of the control was to stabilize the set point temperature of the reaction mixture by a two-point controler. In dependence on the rate of response of the system to a change of the section variable either the ideal relay or the relay with hysteresis control algorithmus were used. The results of measurements showed that with the aid of a retractable cooler the temperature could be controlled safely even in those cases, in which the control by the variable flow rate of the coolant was unfeasible. The verification was carried out in the open-loop instable operating point of the reactor.

Adaptive temperature control in chemical reactors a simplified method maximizing productivity of the batch reactor

1982 ◽  
Vol 47 (1) ◽  
pp. 251-261 ◽  
Author(s):  
Josef Horák ◽  
František Jiráček ◽  
Libuše Ježová
Keyword(s):  
Mathematical Model ◽  
Temperature Control ◽  
Cooling System ◽  
Batch Reactor ◽  
Cooling Capacity ◽  
Present Value ◽  
Chemical Reactors ◽  
Exothermal Reaction ◽  
Variable Activity ◽  
Simplified Method

A simplified method has been proposed in the paper of adaptive temperature control in a batch reactor with an exothermal reaction. The control has been effected by a two-level controller enabling the degree of utilization of the cooling capacity of the reactor to be maintained on a present value. The degree of utilization of the cooling capacity was evaluated from the ratio of the time for which the cooling system was in action to that during it was idled. The method has been applied to reactors with a small inertia of the cooling system. The study has been based on the simulation by a mathematical model of the system. Experimental verification of results of the simulation has been caried out a laboratory batch reactor with variable activity of the catalyst.

The Study on Effects of Thermal Aging of Dissimilar Weld Zone in a Primary Reactor Cooling System

2004 ◽  
Vol 261-263 ◽  
pp. 1689-0 ◽  
Author(s):  
Jae Do Kwon ◽  
Seung Wan Woo ◽  
Y.H. Choi
Keyword(s):  
Thermal Aging ◽  
Cooling System ◽  
Operating Temperature ◽  
Weld Zone ◽  
Accelerated Aging ◽  
Mechanical Tests ◽  
Dissimilar Weld ◽  
Long Period ◽  
Reactor Operating ◽  
Cast Stainless Steel

In a primary reactor cooling system(RCS), a dissimilar weld zone exists between austenitic-ferritic duplex cast stainless steel(CF8M) in a pipe and low-alloy steel(SA508 cl.3) in a nozzle. Thermal aging is observed in CF8M as the RCS is exposed for a long period of time to a reactor operating temperature between 290 and 330°C, while no effect is observed in SA508 cl.3. An investigation of the effect of thermal aging on the various mechanical properties of the dissimilar weld zone is required. The purpose of the present investigation is to find the effect of thermal aging on the dissimilar weld zone. The specimens are prepared by an artificially accelerated aging technique maintained for 100, 300, 900, 1800 and 3600 hrs at 430°C, respectively. The various mechanical tests for the dissimilar weld zone are performed for virgin and aged specimens.

A High Angle, Double Tilting Cold Stage for the AEI EM7

1974 ◽  
Vol 32 ◽  
pp. 450-451
Author(s):  
P.R. Swann ◽  
A.E. Lloyd
Keyword(s):  
Habit Plane ◽  
Temperature Control ◽  
Tilt Angle ◽  
Cooling System ◽  
Thermal Drift ◽  
High Angle ◽  
Cold Stage ◽  
High Degree ◽  
Better Than

Figure 1 shows the design of a specimen stage used for the in situ observation of phase transformations in the temperature range between ambient and −160°C. The design has the following features a high degree of specimen stability during tilting linear tilt actuation about two orthogonal axes for accurate control of tilt angle read-out high angle tilt range for stereo work and habit plane determination simple, robust construction temperature control of better than ±0.5°C minimum thermal drift and transmission of vibration from the cooling system.

A simulation apparatus for the experimental study of batch reactor control methods

1986 ◽  
Vol 51 (6) ◽  
pp. 1259-1267
Author(s):  
Josef Horák ◽  
Petr Beránek
Keyword(s):  
Experimental Study ◽  
Closed Loop ◽  
Dynamic Properties ◽  
Batch Reactor ◽  
Exothermic Reaction ◽  
Electric Heating ◽  
Batch Reactors ◽  
Exchange Area ◽  
The Stability ◽  
Methods Of Control

A simulation apparatus for the experimental study of the methods of control of batch reactors is devised. In this apparatus, the production of heat by an exothermic reaction is replaced by electric heating controlled by a computer in a closed loop; the reactor is cooled with an external cooler whose dynamic properties can be varied while keeping the heat exchange area constant. The effect of the cooler geometry on its dynamic properties is investigated and the effect of the cooler inertia on the stability and safety of the on-off temperature control in the unstable pseudostationary state is examined.

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