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The high pressure difference between the inlet and outlet of the air preheater in coal-fired power plants has always been a problem that plagues the operation of the power plant. If the pressure difference of the air preheater can be predicted in advance and adjusted in time, it will be beneficial to the safe operation of the power plant. Based on the distributed control system (DCS) big data of a 660 MW coal-fired boiler, the BP neural network and support vector regression (SVR) methods were used to model the pressure difference between the inlet and outlet of air preheater in the power plant.Comparing the prediction results of the two models, it is found that the BP neural network model is more suitable for the prediction of the pressure difference between the inlet and outlet of the air preheater under the background of big data. Aiming at the inherent shortcomings of BP neural network model such as local optimization and slow convergence speed, the particle swarm optimization (PSO) was used to improve it, and a PSO-BP neural network model was proposed. The results show that the PSO-BP neural network model has the best comprehensive performance, the highest accuracy in predicting the change in the pressure difference between the inlet and outlet of the air preheater, and the strongest generalization ability.

SO3 is one of pollutants in flue gas of coal power plants. It mainly derived from coal combustion in boiler and selective catalytic reduction denitrification system. The content of SO3 in flue gas were influenced by the combustion mode, sulfur content in fuel, composition of denitrification catalyst and fly ash. SO3 and water vapour generated H2SO4 droplets. Sulfate secondary particles in atmosphere could cause haze, acid rain and other disastrous weather. High concentration of SO3 could cause blockage and corrosion and affect the safe operation of the units. The generation mechanism of SO3 was discussed. The latest research progress on control and removal technology of SO3 was summarized. The study in this paper provides a reference for pollutant treatment in coal-fired power plants.