Control of coupled PDEs–ODEs using input–output linearization: Application to a cracking furnace

This paper presents a new control technique for handling the tube wall temperature and mass production rate of Vinyl Chloride Monomer (VCM) in a cracking furnace by taking advantage of finite element method and Input–Output (I/O) linearization. I/O linearization technique is extended to apply to a coupled PDE–ODE system. A finite element based, open-loop state observer is used to estimate the information of the process states and state derivatives. The feedback I/O linearizing controller is designed to force the tube wall temperature to follow a desired trajectory. To handle the mass production rate of VCM, an EDC feed velocity controller with a proportional-integral structure is formulated. The control performances of the developed control method are demonstrated through servo and regulatory tests.

► We propose a nonlinear control system for coupled PDEs–ODEs of a EDC cracking furnace.
► A feedback I/O linearizing controller is used to track an outlet tube wall temperature by adjusting a fuel gas flow.
► A PI controller is used to handle a mass production rate of VCM by adjusting an EDC feed velocity.
► The proposed method provides good performance and a capability to reject a disturbance through servo and regulatory tests.