183567921-Chap-1-CRE-_预防医学_医药卫生_专业资料.pptVIP

Chemical Reaction Engineering CHE594 Assoc. Prof. Dr. Wan Shabuddin Wan Ali, AMN Office: Level 19, Tower 2 (ST) Tel: 03-5543 6351 H/P: 019-3511182 Januari 2009 Chapter 1 Overview of Chemical Reaction Engineering - Classification of Reactions - Variables Affecting the Rate of Reaction - Definition of Reaction Rate - Speed of Chemical Reactions - Examples and Problems Chapter OneOverview of Chemical Reaction Engineering Every industrial chemical process is designed to produce economically a desired product from a variety of starting materials through a succession of treatment steps. Figure 1.1 shows a typical situation. To find what a reactor is able to do we need to know the kinetics, the contacting pattern and the performance equation. We show this schematically in Fig. 1.2. the performance equation; relate input to output for various kinetics and various contacting patterns: This important, Because with this expression we can compare different designs and conditions, find which is best, and then scale up to larger units. [1] Classification of Reactions There are many ways of classifying chemical reactions. In chemical reaction engineering probably the most useful scheme is the breakdown according to the number and types of phases involved, the big division being between the homogeneous and heterogeneous systems. A reaction is homogeneous if it takes place in one phase alone. A reaction is heterogeneous if it requires the presence of at least two phases to proceed at the rate that it does. Table 1.1 shows the classification of chemical reactions . Variables Affecting the Rate of Reaction In homogeneous systems the temperature, pressure, and composition are obvious variables. In heterogeneous, the problem becomes more complex. Material may have to move from phase to phase during reaction; hence, the rate of mass transfer can become important. The rate of a reaction can be expressed as the rate of disappearance of a reac