Abstract
In limestone-gypsum wet flue gas desulfurization process, the change process of pH value of slurry in absorption tower is a typical nonlinear system with time delay and various uncertainties, so it is difficult to establish an accurate mathematical model of slurry pH control process. According to the pH control process of the slurry of wet flue gas desulfurization process, a model-free adaptive control algorithm based on compact form dynamic linearization (CFDL-MFAC) is designed to realize the tracking control of the pH value of the slurry. Due to various interference factors in the pH control process of slurry in absorption tower, it is easy to cause jump change of control system parameters and even structure. Therefore, a model-free adaptive control algorithm based on switching strategy is proposed in this paper. According to different working conditions, several model-free adaptive controllers are established. The stability of the algorithm is analyzed for the two cases of fixed system parameters and jumping system parameters. It was found that the model-free adaptive controller based on the switching strategy can switch multiple controllers under the condition of system parameter jump, so as to realize the fast tracking control of the slurry pH value of the system absorption tower under different working conditions. Through this method, the overshoot can be reduced and the control quality can be improved.
Highlights
Sulfur dioxide is one of the main air pollutants. e pollution caused by sulfur dioxide has a great impact on the economy, and has a great threat to human health
Low pH value will inhibit the absorption of sulfur dioxide. erefore, it is of great significance to accurately control the pH value of absorption tower slurry in wet flue gas desulfurization (WFGD) process
In order to solve this problem, a model-free adaptive control algorithm based on switching strategy is proposed in this paper. e simulation results show that the model-free adaptive controller based on the switching strategy can switch multiple controllers according to different working conditions, effectively reduce the overshoot, and quickly realize the tracking control of the slurry pH value of the absorption tower
Summary
Sulfur dioxide is one of the main air pollutants. e pollution caused by sulfur dioxide has a great impact on the economy, and has a great threat to human health. More than 55% of sulfur dioxide comes from coal combustion in coal-fired power plants. China’s growing demand for electricity leads to the continuous growth of coal consumption, which leads to the increase of sulfur dioxide emissions from coal combustion. Erefore, the reduction of sulfur dioxide emission from coal-fired power plants will improve the atmospheric environment quality. Process [1, 2] is most widely used in coal-fired power plant desulfurization system. In this process, the pH value of absorber slurry is a key factor that directly affects the absorption efficiency of sulfur dioxide in flue gas and the quality of final product (gypsum) [3, 4]. Low pH value will inhibit the absorption of sulfur dioxide. erefore, it is of great significance to accurately control the pH value of absorption tower slurry in WFGD process
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