Adaptive Integral Sliding Mode Control for Temperature Regulation in Gas-Phase Ethylene Polymerization Fluidized Bed...

Area of Science:

• Chemical Engineering
• Process Control
• Polymerization Reactors

Background:

• Gas-phase polymerization reactors exhibit challenging nonlinearities and exothermic kinetics.
• Conventional PID control lacks robustness; NMPC can be sensitive to model mismatch.

Purpose of the Study:

• To propose and evaluate an Adaptive Integral Sliding Mode Control (AISMC) strategy for temperature regulation in nonlinear gas-phase reactors.
• To enhance disturbance rejection and steady-state accuracy while mitigating chattering.

Main Methods:

• Development of an AISMC controller integrating adaptive gain adjustment and an integral sliding surface.
• Closed-loop simulations over an 18-hour dynamic scenario with setpoint changes, catalyst variations, and feed flow disturbances.

Main Results:

• AISMC achieved the best tracking performance (MAE = 0.092 K), outperforming PID (MAE = 0.794 K) and conventional sliding mode control (MAE = 0.179 K).
• NMPC showed degraded performance (MAE = 0.809 K) under disturbances.
• AISMC demonstrated superior accuracy and disturbance rejection without excessive computational cost.

Conclusions:

• AISMC provides a robust, accurate, and computationally feasible solution for temperature control in industrial gas-phase polymerization reactors.
• The proposed controller effectively balances performance and real-time applicability.