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Dynamics Analysis of the behavior of Fine Particulate Matter in Pulverized Coal Combustion

Author: Geng
Tutor: LiuChaoZuo；ZhengChuGuang
School: Huazhong University of Science and Technology
Course: Thermal Power Engineering
Keywords: Respirable particulate matter Method of Moments Polydisperse system Condensation Brown collision condensate and Trap
CLC: TK227.1
Type: Master's thesis
Year: 2005
Downloads: 98
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Abstract

Atmospheric respirable particulate matter has become a prominent problem of atmospheric pollution, and increasingly attracted attaches great importance to the countries in the world. To understand the mechanism of respirable particulate matter generated in the combustion process and the growth process is a prerequisite for control of particulate matter generated in the combustion process, the core issue is one of respirable particulate matter, the dynamics of the migration process analysis. Process wherein particle condensation, between the particles of irregular Brownian collision coagulation and coarse and fine particle trapping effect between the distribution change of the particle size of the particles plays a very important role. Simulation and prediction of these processes is one of the hotspots of aerosol dynamics. This paper summarizes the particle condensation in Brownian coagulation collision as well as the thickness of the particle trapping effect of progress and mathematical models, algorithms based on the initial distribution of the particles make a reasonable normal distribution logarithmic assumption The use of the method of moments (Moment Method) polydisperse system particulate separate condensation process, Brownian coagulation process, the thickness particle trapping role in the process as well as their common role in the process under different initial conditions simulated. The analytical solution of the obtained results with the literature coincide. Monodisperse system, Brown collision coagulation with condensation process simulation results showing the obvious self-holding characteristics; initial width of the particle size distribution and significant change coagulation initial coagulation rate and generate particles average diameter, the resulting particle size is still wide distribution, but to achieve self-holding. Therefore creating a model of the coal combustion particulate emissions, it is necessary to consider the wide distribution of particles and non-self-holding characteristics, but may be assumed to achieve self-holding for the migration of the particulate matter in the flue. For a typical bimodal distribution of polydisperse systems, the simulation results show that: the trapping coarse particles to fine particles have a significant effect on the number density of fine particles, average particle size, dispersity; Moreover, with the increase of the proportion of fine particles , the decay rate of the particle number density was significantly increased, it can be inferred that the initial mineral evaporation / initial concentration of fine particles are very small the influence of the concentration of fine particles of the final emissions; the initial dispersion of the fine particles of the initial increase Assembly make the frequency of occurrence of the capture process is greatly reduced. Comparative calculations show that the impact of different coarse particles have an average particle size of the capture process, the particle size of the coarse particles is the decisive parameter affecting the trapping effects: In the same quality under a load, the larger the particle size of the coarse particles, the fine particles capture the role better. Capture process the final distribution of the particles in different fine particle dispersion is considered alone, it is found that in addition to the attenuation of the number of particles, the remaining parameters did not show a strong self-holding characteristics, it can be seen that, if you want to consider grain growth as well as changes in the dispersibility of the collision Brown

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