Basic design equations for a tubular reactor

The basic equation for a tubular reactor is obtained by applying the general material balance, equation 1.12, with the plug flow assumptions. In steady state operation, which is usually the aim, the Rate of accumulation term (4) is zero. The material balance is taken with respect to a reactant A over a differential element of volume 8V, (Fig. 1.14). The fractional conversion of A in the mixture entering the element is aA and leaving it is (aA + SaA). If FA is the feed rate of A into the reactor (moles per unit time) the material balance over 8V, gives  

If the reaction mixture is a fluid whose density remains constant throughout the reaction, equation 1.35 may be written in terms of x moles of reactant converted per unit volume of fluid. Since x- °aCa0, equation 1.35 becomes  

REACTOR DESIGN-GENERAL PRINCIPLES v, the volumetric flowrate of the reaction mixture. 

This equation can be derived directly from the general material balance equation above (Fig. 1.14) by expressing the flow of reactant A into and out of the reactor element SV, in terms of the volumetric rate of flow of mixture v, which of course is only valid if v is constant throughout the reactor. 

Production of Ethylene by Pyrolysis of Ethane in an Isothermal Tubular Reactor 

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