In a chemical processing plant, an exothermic reaction A+B→C is carried out in a continuous stirred-tank reactor (CSTR). The reaction rate is highly sensitive to the concentration of reactant B. To maintain optimal reaction conditions and product quality, the molar feed ratio of A:B must be strictly controlled at 1:1. However, fluctuations in the feed stream composition of B are common due to upstream processing variability. To address this, a control strategy combining feedforward and ratio control has been proposed. The feedforward control uses a real-time analyzer to measure the concentration of B in the feed stream and adjusts the flow of A accordingly, while the ratio controller adjusts the flow of A to maintain the 1:1 molar feed ratio with B. a) Explain how the feedforward control mechanism helps in dealing with the variability in the concentration of B and its impact on the stability of the CSTR operation. b) Discuss the role of ratio control in conjunction with feedforward control in this scenario, and how it contributes to the robustness of the control strategy. c) Suppose there is a delay in the response of the feedforward control due to the lag in the analyzer measurement. How might this delay affect the performance of the control strategy, and what modifications could be implemented to mitigate the impact of this delay?
In a chemical processing plant, an exothermic reaction A+B→C is carried out in a continuous stirred-tank reactor (CSTR). The reaction rate is highly sensitive to the concentration of reactant B. To maintain optimal reaction conditions and product quality, the molar feed ratio of A:B must be strictly controlled at 1:1. However, fluctuations in the feed stream composition of B are common due to upstream processing variability.
To address this, a control strategy combining feedforward and ratio control has been proposed. The feedforward control uses a real-time analyzer to measure the concentration of B in the feed stream and adjusts the flow of A accordingly, while the ratio controller adjusts the flow of A to maintain the 1:1 molar feed ratio with B.
a) Explain how the feedforward control
b) Discuss the role of ratio control in conjunction with feedforward control in this scenario, and how it contributes to the robustness of the control strategy.
c) Suppose there is a delay in the response of the feedforward control due to the lag in the analyzer measurement. How might this delay affect the performance of the control strategy, and what modifications could be implemented to mitigate the impact of this delay?
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