Study On Droplet's Evolution In Chimney With Flue Gas Wet Desulphurization

Phenomenons such as gypsum rain,chimney corrosion and cylinder head icing,directly related to the chimney,are common in thermal power plants and have negative effects on safety,health and normal operation of plants.Generations of these phenomenons have direct connections with the quantity and the distribution of droplets in the chimney.The droplets growth,typical evolution process of discrete system dynamics,can be studied using the population balance modeling method.The population balance modeling method is widely applied in various fields of engineering and science.It can quantitatively describe dynamics events such as collision,aggregation,growth,breakage and sedimentation of particles in the discrete system,thus,the evolution rule of particle size distribution can be obtained.In this thesis,distribution and evolution rules of droplets in the wet desulphurization chimney are studied in the way of numerical simulation in one-dimensional,twodimensional,three-dimensional space in turn.Among which,one-dimensional and twodimensional issues are solved by programming.Assuming that droplets totally follow the motion of the smoke,on basis of flow field obtained by the software simulation and dynamic nuclear models properly chosen,Monte Carlo method and sectional method are respectively used to solve the dynamic evolution process of droplets.Distribution and evolution rules of parameters such as average quantity density,average diameter and volume fraction of droplets along the height and radius of the chimney are obtained.The droplets' three dimensional distribution and evolution characteristics are obtained by coupling population balance model and multiphase flow model provided by FLUENT,and the simulation results of FLUENT are used to contrast with those results of programming.Study shows that one dimensional programming results are qualitatively correct,and two dimentional programming results are good agreement with results obtained by FLUENT both in qualitative and quantitative.In addition,calculation by programming are more time-saving than FLUENT simulation.