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Reactor Design II-Fourth Year Dr.Ali N.Khalaf

University of Basrah College of Engineering Chemical Engineering Department Fourth Year First Semester Reactor design II

Chapter One Non-Isothermal Reactor Design

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Chemical Engineering Department- University of Basrah

Reactor Design II-Fourth Year Dr.Ali N.Khalaf

1- Optimal Temperatures for Isothermal Reactors: Reaction rates almost always increase with temperature. Thus, the best temperature for a single, irreversible reaction, whether elementary or complex, is the highest possible temperature. Practical reactor designs must consider limitations of materials of construction and economic tradeoffs between heating costs and yield, but there is no optimal temperature from a strictly kinetic viewpoint. Reversible reactions, since these are a special form of multiple reactions, usually exhibit an optimal temperature with respect to the yield of a desired product. One must specify the temperature at which to operate. Consider the elementary, reversible reaction

Suppose this reaction is occurring in a CSTR of fixed volume and throughput. It is desired to find the reaction temperature that maximizes the yield of product B. Suppose Ef>Er, as is normally the case when the forward reaction is endothermic. Then the forward reaction is favored by increasing temperature. The equilibrium shifts in the desirable direction and the reaction rate increases. The best temperature is the highest possible temperature and there is no interior optimum. For Ef