The performance of a tubular reactor with recycle was investigated by obtaining residence time distribution curves with tracer experiments. The experimental reactor was the copper tubing 7 meters long and 1/2 inches in diameter, in the form of a spiral with the recycle line which consisted of a pump and PVC tubing, 1.5 meters long and 1/4 inches in diameter.
From obtained residence time distribution curve the experimental reactor was simulated with recycle reactor model. Experimental results showed that the actual recycle ratio of the reactor was the major factor contributing to the variation in the mixing level for the recycle reactor and that the relationship between actual recycle ratio Ra and simulated recycle ratio R showed a linear relationship R= 1.3 Ra + 3.3.
The saponification reaction of ethyl acetate with sodium hydroxide was used to compare the predicted values with the experimental data. The observed steady state conversions of sodium hydroxide and the transient responses of the outlet sodium hydroxide concentration to a step change in the inlet reactant concentration were in good agreement with the theoretical values predicted by the recycle model.
The experimental reactor was also simulated with the tanks-in-series model to compare the recycle reactor model with the tanks-in-series model. The recycle reactor model involved simpler calculation procedures and gave better predictions on conversion than the tanks-in-series model.