Projection operator technique was proposed as a systematic method to derive a simplified effective transport equation from the basic mass balance equation. The procedure of projection operator technique is composed of two steps; first an exact closed equation for the relevant part of objective concentration is derived, and second the closed equation is simplified to an effective transport equation by the adiabatic approximation method. As a result the relationship between the effective transport coefficients and the process structure is obtained. The effective process model derived by such a manner can be applied to process evaluation, process control and process design. As an application of projection operator technique, axi-symmetric mass transfer systems involving fluid flow, chemical reaction and solution-diffusion in multiphase media were treated and extended Taylor dispersion models were obtained. Separation performance in capillary chromatography and Reaction efficiency in a tubular bioreactor were discussed on the basis of the generalized dispersion equations.