| Summary: | 碩士 === 國立成功大學 === 化學工程學系 === 87 === The purpose of Hydrodemetallization (HDM) is to remove the metal components of heavy oil, and increases the life of catalysts. Most of the HDM fixed-bed reactor were packed with uniform activity catalysts. In this study we use egg-shell activity catalysts to examine the characteristics of HDM fixed-bed reactor. By changing the system parameters (Thiele Modulus, feed rate, catalyst pore size, upper limit tempurature and exit concentration), their optimal designs are found , and are compared with those of using uniform activity catalysts.
Accroding the numerical results, we present some perfor-mance charts of using egg-shell and uniform activity catalysts. For given system parameters, we can find the catalyst life and total mass of demetallation from those charts. For the catalysts used , there is a optimal catalyst pore size to maximum its amount of demetallation . Under the normal operating condition, e.g.Φ0=3, the optimal λ* of egg-shell catalysts(p=0.5) is 0.02383, and is 0.02876 for the uniform activity catalysts . In general, the larger the value of Φ0 , the shorter the life of catalysts. Theλ* would be bigger whenΦ0 increase , and decrease with β0 increasing. If the upper limit tempurature of the reactor is raised , the value of λ* would be smaller. With a high-value of Φ0 , the performance of the egg-shell catalysts is better than those of uniform activity catalysts. The design of a two-stage reactor can improve the total mass of demetallation. When different kind of catalysts are considered, we suggest the upper-stage packed with uniform activity catalysts and the lower-stage packed with egg-shell activity catalysts.
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