Sliding mode control for gasifier reactor temperature control

Abstract

This paper presents a sliding mode control (SMC) design for gasifier reactor temperature control. Temperature control is a critical aspect  of biomass gasification for quality syngas production. However, accurate modeling and effective control method are the major challenges  of gasifier reactor temperature control. The gasification system processes are not yet well understood to model from the first  principle due to the complex and nonlinear nature of the process. Also, conventional control methods such as proportional, integral, and  derivative control have not been effective in controlling gasification systems. Hence, this work has used experimental data from a 500 kVA  updraft gasifier reactor to develop a data-driven mathematical model. The system identification result predicts 86.36% goodness of  fit on the model data and 88.26% on the validation data. Discrete time sliding mode control has been designed from the model and  implemented in Simulink to investigate the performance of the control method on the gasifier. The result of the system time response  shows that the controller effectively drives the temperature monotonically from 25°C to 700 °C in finite time (11.37 minutes). It also establishes a quasi-sliding motion with an ultimate band of ±1℃ for the remainder of the simulation time. Hence, the control technique  guarantees optimal temperature control for any feedstock type which will result in higher conversion efficiency, more syngas yield, and  improve syngas quality and durability of the gasifier reactor among others.