Dynamic control method of flue gas heat transfer system in the waste heat recovery process

A new flue gas waste heat recovery system and its control strategy are proposed based on the intelligent control technology and the principle of phase-change heat transfer. It is composed of flue gas heat transfer system (FGHTS) and air heat transfer systems (AHTS). The system pressure and outlet flue gas temperature are adjusted by blower frequency in the AHTS and the concentration of lithium bromide-water in the FGHTS, respectively. For FGHTS, a dynamic control method is proposed based on improved particle swarm optimization (PSO). In this method, the optimization ability and the convergence of PSO algorithm are affected by inertia weight and fitness function. The inertia weight strategy with the inverted S-shaped function (IWS-ISF) can enhance the global search ability in the initial stage and the local search ability in the later stage compared with other inertia weight strategies. Meanwhile, the integral time absolute error (ITAE) fitness function is improved by introducing overshoot into ITAE, and the improved fitness function is defined as IITAE fitness function. The improved PSO algorithm based on IITAE fitness function can reduce the overshoot of FGHTS by 66.23%. This paper can provide a theoretical basis for improving the control performance of the new system.