Numerical simulation study on flow field optimization of electrostatic precipitator inlet flue duct in coal-fired units

Resistance increase of connecting flue ducts between environmental protection facilities is one of the main factors influencing fan energy consumption increase in coal-fired units. Accordingly, it is an effective method of saving energy and reducing consumption to optimize the flow field of flue ducts and to reduce resistance and fan energy consumption in coal-fired power plants. CFD numerical simulation was applied to optimize the inlet flue duct of the electrostatic precipitator in a 660 MW coal-fired unit. The varying rules of flue duct resistance, fan energy consumption, ash mass flow distribution, ash concentration and guiding plates wearing rate were studied with a comparative analysis of five different schemes. The results showed that the flue duct resistance was reduced by 28.7% through setting reasonable structural form and quantity of guiding plates. A maximum fan energy consumption of 190 kW·h could be saved for a single unit, and the energy saving and consumption reduction were remarkable. The addition of guiding plates could regulate the distribution ratio of ash mass flow in the flue gas. After optimization, the deviation of ash mass flow distribution ratio reduced from 14.8% to 6.6% on sides A and B, which improved the comprehensive removal efficiency of dust particles by electrostatic precipitator. The optimization of the flue flow field not only improved the uniformity of ash concentration field distribution, but also reduced the wearing rate of guiding plates. After optimization, the average wearing rate of guiding plates decreased from 1.33×10⁻⁷ to 0.56×10⁻⁷ kg/(m²·s), with a decrease of 57.6%. The service life of guiding plates was 2.4 times that before optimization, and the safety and reliability of the unit operation improved.