Chemical Reactor

Abstract

This chapter focuses on various types of chemical reactors such as stirred tanks, empty or packed beds in tubes, vessels and shell-and-tube devices, and highly specialized configurations in which heat transfer may be provided. Almost every kind of holding or contacting equipment has been used as a chemical reactor at some time, from mixing nozzles and centrifugal pumps to the most elaborate towers and tube assemblies. Stirred tanks are the most common type of batch reactor, where stirring is used to mix the ingredients initially, to maintain homogeneity during reaction, and to enhance heat transfer at a jacket wall or internal surfaces. The ideal behavior of tubular flow reactors (TFR) is plug flow, in which all nonreacting molecules have equal residence times. Anyback-mixing that occurs is incidental, which is the result of natural turbulence or that induced by obstructions to flow by catalyst granules or tower packing or necessary internals of the vessels. TFRs may be of pipe diameters ranging from 1 to 15 cm, or they may be vessels of diameters measured in meters. In general, the construction of TFRs is dictated by the need for accommodation of granular catalysts as well as for heat transfer. Kilns and hearth furnaces are primarily used for high temperature services, and their usual construction is steel-lined with ceramics, sometimes up to several feet in thickness.