NEAT OPERATION VERSUS USING EXCESS REACTANT

NEAT OPERATION VERSUS USING EXCESS REACTANT 

The reactive distillation columns considered in previous chapters were all operated in neat mode. The two reactants are fed in exactly the correct amounts to satisfy the stoichiometry of the reaction. The control system must be able to detect any imbalance, which will inevitably result in a gradual buildup of one of the reactants and a loss of conversion and product purities. 

An alternative to operating neat is to operate the reactive column with an excess of one of the reactants. This eliminates the need to perfectly balance the reactant feeds in the reactive column itself, which makes the control of the reactive column easier. However, this mode of operation may have the disadvantage of requiring the recovery and recycle of the reactant that is in excess. The flowsheet typically consists of a two-column system a reactive column and a recovery column. 

We would expect that a single reactive column that is operated neat will have lower capital investment and energy costs than a two-column system. The purpose of this chapter is to give a quantitative comparison of these two alternative processes. 

The neat one-column system may require a composition analyzer to detect the inventory of one of the reactants so that the fresh feed can be adjusted. Because composition analyzers are expensive and sometimes unreliable, the economic advantages of the one-column system need to be assessed. 

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NEAT OPERATION VERSUS USING EXCESS REACTANT... 

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