Phase blending static mixing process and apparatus

A fluid stream including separate layers of plural components is mixed by dividing the fluid stream into a plurality of substreams, reorienting and recombining the substreams in a chamber, and repeating the steps of dividing, reorienting and recombining until a desired degree of mixing of the components is obtained. The substreams of a given stage or group of substreams are controlled so that the substreams are longitudinally dephased with respect to each other such that the fluids of the substreams are longitudinally blended when recombined. The dephasing is achieved by providing that at least selected of the passageways for the substreams of a given stage of the mixer are dimensioned such that the total resistances to flow of the fluid of the substreams passing through the selected passageways, from the beginnings thereof to the ends thereof, are unequal. Such differing total flow resistances may be achieved by providing selected of the passageways with unequal cross-sectional areas, or alternatively with unequal lengths.