Modeling of closed-loop flue gas path system for desulfurization in power plant under severe load changing conditions

Abstract

In this paper, a mathematical modeling of the flue gas path system with closed-loop controller for wet desulfurization with lime in Mae Moh coal power plant, Thailand is presented. The modeling using various polynomial structures and the parameter identification of the plant, the controller and the sensor are performed with the emphasis on the plant. Since the goal is to predict the operating condition where the system is tripped and causing the disruption in electricity generation of the plant, the validation of the model is demonstrated against the hard conditions, where rapid changes of system load causing the system tripped events occurred. Due to the limitation on the existing data acquisition system causing the low resolution on the quality of the collected data, two data treatment processes are introduced and compared, i.e., the linear interpolation with delay and the Piecewise Cubic Hermits Interpolating Polynomial (PCHIP) technique for the best performance selection. The model parameters are estimated and compared based on a least squares criteria. The controller is configured based on the adapted PI controller of the actual system. The performance of proposed system models are given in terms of root-mean-square error (RMSE). Based on the simulation results, it is found that the 2nd-order polynomial model with linear interpolation with delay is the most promising and delivers us the satisfactory performance under both normal load changing and during the tripped event.