Laboratory experiment: Residence Time Distribution (Cascade)
Behaviour of Non-Ideal Reactors
In non-ideal reactors, different flow effects can occur. These effects can influence the ideal behaviour strongly or weakly. They can affect the reactor design, the yield or temperature development of a chemical process.
Dead Zones and Short Circuits
So called dead zones or stagnant region can appear in technical reactors. Areas with a low or no mixing are meant by this. This reduces the available effective reaction volume. A further effect in non-ideal reactors is a short circuit current. An unfavourable location for input and output causes a portion of the reactants to be transported directly to the output before that portion has been able to be part of the reaction.
Further non-ideal conditions can occur depending on the state of the mixing of the reaction fluids. A complete mixing of the reactants only occurs with low-viscosity fluids and gases - resulting in a micro fluid. In an incomplete mixture, local concentration differences will exist. This effect is called segregation. Segregation effects always occur in heterogeneous systems (e.g. suspensions and emulsions). Segregated elements in a reactor may cause different residence time distribution differing from ideal behaviour and can influence the performance of the reacting system. This special type of non-ideal conditions can also be determined by the experimental determination of the residence time distribution.