Separation of Organic Vapors from Air with Membranes

Abstract

The removal and recovery of hydrocarbon vapors from gas streams by means of membrane technology is finding increasing acceptance in the chemical and petrochemical industry. At present 20 membrane vapor recovery units are in operation or in construction phase in Europe.

The description of the membranes for this growing appliction is given. The membranes applied are thin-film composite membranes and it is explained how both, the microporous substructure and the selective layer, determine the membranes selectivity. The role of diffusion coefficient and solubility of the organic vapor in the pore-free selective layer is discussed.

The influence of important process parameters like pressure and temperature on membrane performance is explained. The chapter concludes with a description of the operating experience of a number of membrane systems for vapor recovery.

It is pointed out that for many applications a hybrid system, i.e. combination of a membrane stage with catalytic incineration, pressure swing adsorption or gas engine, is the best solution. New applications like a vapor return system at gas filling stations with an integrated membrane module will be discussed.