Application of Two Models for Removing VOCs by Catalytic Incineration
|Keywords:||觸媒焚化;揮發性有機物;效率因子;孔隙內擴散;質傳限制;catalytic incineration;VOCs;effectiveness factor;pore diffusion;mass transfer limitation|
|Abstract:||在揮發性有機物之控制技術中，以觸媒焚化法 (Catalytic Incineration) 處理對工廠所排放之揮發性有機物其去除效率可達90%以上，且具有將有機物完全氧化之優點。而針對不同的揮發性有機物或觸媒型態，其觸媒焚化器之設計考量亦有不同。本研究同時發展二維解析解模式及效率因子模式，並分析比較其適用性。此外並將其利用來設計處理有機物(苯、乙基苯、苯乙烯及甲苯)之觸媒反應器大小，以及孔隙內擴散及反應器外擴散對觸媒反應的影響探討。
Catalytic incineration is one of the VOCs control techniques that has the advantages of high efficiency and complete oxidation. There were two types of models currently used for the design and improvement of catalytic incineration process, the lumped parameter model and the mass transfer model. However, their applications and limitation have not been compared and studied. In this study, a two-dimensional mass transfer model and one-dimensional effectiveness factor model were developed and their applications were compared. They were then used to design the catalytic incineration reactor and to analyze the effects of pore diffusion and external diffusion. An analytical solution of the two-dimensional mass transfer model was derived so that both models are simple and can be applied easily. The results indicated that two-dimensional analytic solution model has a better prediction in the VOCs removal efficiency and then can be applied to design the catalytic incineration reactor. Using the catalyst data in the literature, the design results showed that when the channel pitch is 0.35cm and temperature is 575°K, the space velocity has to be controlled to below 23000hr-1 for ensure 90% removal efficiency. As a result of comparison of the four VOCs, benzene, ethylbenzene, styrene and toluene, it found that the adsorptive capacity of benzene among the four is the smallest compound. The influence of pore diffusion on benzene destruction is the largest at higher temperatures while it is the lowest at temperature higher than 460°K. On the other hand, benzene is suffered most from external diffusion at high temperature.
|Appears in Collections:||Thesis|