Dynamic modeling, simulation and control (using MPC) of an industrial steam reformer

Dynamic model used for simulation of an industrial side-fired steam reformer comprises coupled PDEs for concentrations of different components and temperature of the gas phase (i.e., outside the catalyst particles), and second order ODEs for concentrations of components in the catalyst phase (i.e., in the pores of the catalyst particles). A MATLAB^® code is developed to solve these equations, and used for analysis of 3 idealized disturbances in the input variables. Effects of 1) step increase in the inlet feed temperature; 2) step decrease in the inlet steam to CH₄ ratio; and 3) step increase in the inlet H₂ to CH₄ ratio; on different output variables (along axial position and time) are studied. Control problems solved using the code developed for solving dynamic model and MPC toolbox in SIMULINK® are: 1) Controlling the exit hydrogen and CO mass flow rates at desired values for a step increase in the inlet feed temperature (T_in) by manipulating furnace gas temperature (T_g), H₂ to CH₄ and steam to CH₄ ratios; 2) Controlling the exit H₂ and CO mass flow rates at desired values for a step decrease in the inlet flow rate of methane by manipulating T_g, H₂ to CH₄ and steam to CH₄ ratios. The dynamic profiles obtained for different variables after solving the above two problems are analyzed.