Study Of Numerical Simulation And Experiment For Gas Flow Organization And Optimizing In Inlet Flue Of Precipitator Used In Coal-fired Power Plant

Airflow distribution in inlet flue of precipitator used in coal-fired power plant has an important influence on its overall efficiency. Flue flow field organization control in inlet flue of dust removal system focus on distribution of gas flux and the distribution of gas velocity on the inlet flue section. Though there are some specific regulation in many standard about various precipitators about distribution of gas flux and the distribution of gas velocity on the inlet flue section. But it lacks of the specific measures to achieve these goals. Especially, about the optimizing design for the existing precipitators. Using the inlet flue of electrostatic fabric filter used in NO.14 unit in a coal-fired power plant and the inlet flue of bag filter used in in a 350 MW coal-fired power plant as examples, the air distribution of the inlet flue was numerically simulated by CFD. The problem of original structure and the causes leading to the non-uniform distribution of gas flux and uneven distribution of gas velocity on the inlet flue section have been analyzed. Optimization scheme have been proposed to achieve following optimal results:(1)The relative difference of gas flux in two rooms of electrostatic fabric filter were less than 2.5%, the distribution of flow in the inlet flue tend to equilibrium. The mean square root values of the gas velocity distribution on the inlet section of two rooms were less than 0.20. The distribution of velocity tend to uniform. Optimized results met the technical requirements in different operation condition.(2)The relative difference of gas flux in five bag filters were less than 2.5%, the distribution of flow in the inlet flue tend to equilibrium. The mean square root values of the gas velocity distribution on the inlet section were not more than 0.25, The distribution of velocity tend to uniform. The maximum gas velocity on the inlet section reduced observably, the abrasion caused by high-speed airflow get improved dramatically. Optimized results met the technical requirements in different operation condition.(3)The numerical simulation optimized scheme of the inlet flue of electrostatic fabric filter used in NO.14 unit in a coal-fired power plant has applied in practical engineering of 1.9 million m3/h boiler unit, electrostatic fabric filter works steadily and reliably, and dust removal efficiency improved significantly since it was put into use. Test results show that the filter body resistance loss is less than 700 Pa, dust emission concentration is about 8mg/Nm3. Optimized results met the technical requirements.