The Cascade Control of a Partially Simulated Continuous Stirred Tank Reactor

Abstract

The results of single-loop and cascade control systems are compared to show the advantages of the cascade system over the other in controlling a reactor outlet temperature. Tests were performed for both control systems on a totally simulated and on a partially simulated continuous stirred tank reactor fitted with a cooling jacket. The system disturbance is a combination of step changes in the reactor inlet temperature and throughput and in the jacket coolant inlet temperature, while the jacket flowrate is the manipulated variable. To predict performance, the whole system is simulated on a Honeywell-316 digital computer. This study also assisted in the design of the corresponding partially simulated system. In partial simulation some parts of the system are simulated on the computer while other parts exist as real plant items with on-line linked operation. In this particular research, reactor and jacket inlet and outlet temperatures and reactor throughput are transmitted to the computer as required data for the simulation of the mass balance and the generation of the control action. A signal representing the calculated reaction heat generation is transmitted back to the plant to implement the release of the required exothermic heat of reaction from electrical heating elements. The corrective signal from the simulated control action is also transmitted to the real control valve to regulate the coolant flow. The transmission of these signal sand their conversion to the required form is controlled by the Honeywell Analogue Digital Input/Output System(HADIOS ) To confirm the partial simulation experimental results, total simulation model tests are made using the initial operating conditions of the partial simulation study. The results from the two simulation methods are very close although the total simulation could not model all features of the actual plant and its operation.