Methodology for estimating saving of primary energy with membrane operations in industrial processes

Membrane separation processes can realize significant savings of direct energy (e.g., oil, gas, coal) and indirect energy (intrinsically contained in the materials recovered and/or recycled). Tile methodology of the energy analysis in various industrial cycles is described, and the benefits of these operations, based principally on electrical energy consumption, are evaluated using the definition of ''substitution coefficient'' (primary energy saved vs. 1 kWh of electrical energy consumed). The industrial sectors where this methodology has been applied are: textile (recycle of water, dyes and chemicals); polymer manufacturing (recycle of caprolactame and water); the tanning industry (recycle of sulfides and protein recovery), the dairy industry (saving of thermal energy and recovery of fat substances); and tomato and orange juice concentration (saving of thermal energy). The analyses show very interesting values for the substitution coefficients confirming the convenience of membrane operations from an energetic viewpoint.