An algorithm is presented for treating saturation by limiting only the Integral action in both the Position and Velocity form Proportional Integral Derivative (PID) controllers and the Minimum Variance controller (MVC). The interrelationships between both forms of the PID controller and the PID terms contained in the MVC are shown. Simulation results are presented that show the Improvement obtained by applying the reset windup protection proposed here, rather than the usual antireset windup algorithm, to Proportional and PI Position and Velocity form controllers.

The solution of the steady state model of a packed-bed non-adiabatic reactor using collocation methods is presented. The model equations are non-linear partial differential equations in two spatial variables and time. They are discretized in the radial direction using collocation and the resulting ordinary differential equations are integrated in the axial direction. The solutions using quadratic and quartic polynomial approximations in the radial direction are compared'. The effects of moving the radial collocation point is also examined. The results are compared to those obtained by solving the equations using the method of finite differences. A comparison is also made with reactor models based only on average temperature and concentration profiles.The pilot scale reactor on which this study is based has cooling at the walls and the reactions are the catalyzed hydrogenolysis of n-butane, a highly exothermic set of series-parallel reactions. The reactor operation is characterized by radial temperature gradients and an axial hot spot.

No abstract

No abstract