DISTRIBUTED CONTROL SUBOPTIMAL OPERATING POLICIES FOR ETHANE THERMAL-CRACKING REACTORS

A nonlinear unsteady state optimal control problem for a classical, co nstant diameter ethane thermal cracking reactor is formulated and solv ed. The process is represented by a pseudo steady state mathematical m odel, consisting of mass and heat balance, pressure drop, and coking e quations. The performance index is of an economical nature, representi ng the global benefit of reactor operation over a constant operating t ime. As control variables, the space and time dependent skin tube temp erature, the time dependent steam to hydrocarbon ratio, and the time d ependent feed flow rate were considered. The results are in agreement with the process physicochemical and technological fundamentals.