Features of selective mass transfer in hybrid membrane-sorption systems

Efficiency of recirculation membrane sorption systems for producing oxygen-enriched air

“…In order to achieve an agreement with the equations for calculation of membrane step, it is nec essary to transform the concentrations into molar fractions and convert the volume flow into molar value [14].…”

“…The calculations were based on the sorbent selectivity of 3, and the membrane selectivity was considered to be 7. Figure 2 shows the scheme which enables the implementation of several hybrid single loop mem brane-sorption recirculation systems for gas separa tion differing by the procedure of PSA step filling [24,25]. The recycle in the system is formed due to return ing the retentate flow from the membrane step through the ejector to inlet of sorption step.…”

“…The material balance equation at desorption stage looks like: (14) where V is the volume of adsorber, W psa is the reject flow at PSA stage. Left half of the equation represents an initial stage: the column is fulfilled by the feed mix ture with molar concentrations at pressure .…”

“…Another way to attain the required level of enrich ment in separation system is mixing the recirculation stream with the feed stream in systems with a single recirculation loop [8,13,14]. The principle of the sys X θX…”

“…To calculate the membrane module, we use the sys tem of equations describing the separation of binary gas mixture based on the suggestion of plug flow in the high pressure phase with perpendicular outflow to the low pressure phase according to the methods given in the works [13,14]. The suggestions used for the calcu lation of membrane step are connected with neglect ing of the contribution of axial molecular diffusion (plug flow assumption) for the high pressure phase of membrane step; the penetration of component through membrane at the current point is determined only by concentrations of components at this point of the high pressure phase and the values of pressures in both phases of the step (the suggestion of perpendicu lar outflow), the influence of variations in pressure is neglected, and the flow is considered be one dimen sional and isothermal, and the membrane permeabil ity for the components be constant.…”