Numerical Simulation And Optimization Of The Flow Field Of A Boiler Flue In A Power Plant

The layout structure of the wind and smoke system in a coal-fired power plant not only affects the internal resistance of the wind and smoke pipes,but also affects the normal operation of its connected equipment.In addition,it also plays an important role in the stability and reliability of the operation of the power plant.This article is aimed at a power plant’s unit 3 after the increase in intake and integration,due to defects in the flue design structure,in the actual operation process,the internal flow deviation of the long and short sides of the asymmetric flue is large,make the connection of two induced draft fan surge phenomena will happen often,not the problem of parallel operation,and design scheme is put forward.In this paper,numerical analysis method is used to analyze the flow distribution of the asymmetrical flue,and the problem of the air volume mismatch between the two sides of the inlet is solved by adding baffles,and the optimization analysis method is used to solve the structural defects in the existing design.The research content is as follows:(1)Establish a numerical simulation model according to the original flue design drawings,and divide the grid;the flow field of internal original flue was calculated,and realize the fault reproduction through the streamline diagram and pressure diagram obtained by the numerical simulation;analyze and reveal the original flue design The problems in the structure and the reasons for the failure.(2)The initial transformation plan of the flue is proposed,and the initial transformation plan is numerically simulated.According to its numerical analysis and evaluation results,the performance optimization analysis of the flue reformation is carried out.By continuously adjusting the horizontal position of the baffle,the internal flow balance of the flue is realized,and combined with the actual demand of the power plant,the optimal transformation scheme of the flue performance was determined.(3)Further improve the flue gas flow characteristics inside the flue,and conduct structural optimization analysis for the original flue.First,optimize and analyze the plan of adding arc-shaped slabs of different length on one side;then optimize the plan of adding arc-shaped slabs of different length on both sides;finally,obtain the structural optimization and transformation plan by adjusting the position of the deflector.Research indicates:(1)Reasonable use of the baffle to change the structure of the flue is conducive to achieving a balance of flow in the flue and reducing the vibration of the induced draft fan.When the deflector is 2.105 m away from the long side of the flue,the inlet flow of the long side section is 219.003kg/s,the short side section inlet flow is 222.556 kg/s,and the flow deviation is reduced from 128.752kg/s to 3.553kg/s.Combined with the actual situation of the power plant,this plan is the final transformation plan.(2)An arc-shaped plate with a radius of 1m is added to the corners of the original flue on both sides,and the deflector is 1.65 m away from the long side.At this time,the flue gas fluidity inside the flue is better,and the inlet flow rate at the long side is calculated to be233.42.kg/s,the inlet flow rate of the short side section is 233.734 kg/s,and the flow deviation is small,which is a more optimized modification plan.