An example of a 'Process Intensified' approach
Take a single phase liquid reaction that is moderately exothermic and a maximum allowable reaction temperature of 30°C, above which yield and selectivity drop off sharply: the reaction is fairly fast (95% conversion in 5 secs) and has first order kinetics.; the liquid reagent is fed into process stream at the entry to the reactor.
Take a single phase liquid reaction that is moderately exothermic and a maximum allowable reaction temperature of 30°C, above which yield and selectivity drop off sharply: the reaction is fairly fast (95% conversion in 5 secs) and has first order kinetics.; the liquid reagent is fed into process stream at the entry to the reactor.
The pure PI approach is to carry out this reaction at the fastest possible rate and have a high heat transfer coefficient reactor to allow operation as close to 30°C as possible, using, perhaps, a Printed Circuit Heat Exchanger (PCHE).
The economic approach to PI is to design the reactor while considering the overall cost-benefit-risk to the plant. For example, if competing side reactions are not adversely promoted by operating at a lower temperature, using a simple jacketed mixer with a lower heat transfer coefficient means that the reaction has to be carried out at 20°C, gives the same yield and selectivity, but takes three times as long.
Looking at this stage in isolation, the PI philosophy says that this reaction is inefficient as it is constrained by the heat transfer coefficient of the reactor, but examining the impact of this 'inefficiency' on the complete plant design, the reactor is still extremely compact; the impact on the chemical efficiency is zero, and the overall cost of the reactor is lower.