Elements of Process Reactor Design

The design of a reactor starts with the expression of material balance for any reactant (or product). The basis for all material balances is the law of conservation of matter, which states that matter cannot be created or destroyed in a given system (nuclear reactions are, of course, out of this dictum). Material balance is generally given as  

For the various reactor types this equation simplifies in one way or another, and the resultant expression when integrated provides the basic performance equation for that type of unit. Since in batch reactor or operation, no stream is entering or leaving the reactor, 

A batch reactor is never a steady-state process operator, unlike a continuous process in which a steady state is defined as the state of a process in which there is no change with time of any condition of the process. This includes the amount and average composition of the material within the process, so that in a continuous process, there can be no accumulation or depletion. Notwithstanding an unsteady-operation where composition changes with 

When the process occurs nonisothermally in the reactor, energy balances must be used in conjunction with material balances. The general expression for energy balance is  

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