Question: The process in Figure includes a fired heater, chemical reactor, and heat exchangers to recover energy by heat transfer to other processes in the plant. The goals are to have tight flow control (Fl), tight control of the reactor outlet temperature (T2), and good control of temperatures T3 and T4 in the integrated processes. The sensors and manipulated variables are shown in the figure. Disturbances are set point changes to the process flow and changes in the heating requirements of the heat-integrated processes.
a) Without changing the instrumentation and process equipment, design a control system to achieve the objectives. Discuss whether all objectives can be achieved and if not, why.
(b) By making the minimum changes to the process equipment and instrumentation, design a system that improves the result in (a).
