Heat transfer studies for the design and optimisation of a distillation column to separate an automotive fuel

Methylal, an automotive fuel has been noticed as a diesel alteration additive with relatively high hydrogen-to-carbon ratio. Methylal is more volatile than diesel fuel but it is used as a diesel fuel component because of its 100% miscibility with diesel fuel. An attractive feature of methylal is the reduction of particulate emissions of toxic pollutants without affecting the energy density. Unfortunately, methylal is found to form a minimum boiling azeotrope with methanol whose separation by conventional distillation is impossible. Here, we have introduced an enhanced technique of pressure swing distillation which separates methylal and methanol by exploiting its pressure sensitivity. This work has addressed the design and optimisation of a pressure swing distillation column to separate the azeotropic mixture of methylal-methanol. A novel technique of pressure swing distillation has resulted in the production of pure methylal and pure methanol. The pressure in high pressure column of pressure swing distillation process has been optimised in such a way that there is minimization of overall cost of the process with maximization of product purities. Later on, a process intensification technique of heat integration has been developed which has resulted in 55.2% savings in energy by reducing the overall load of reboiler.