Simultaneous production of high-quality water and electrical power from aqueous feedstock’s and waste heat by high-pressure membrane distillation

Abstract

A new membrane distillation (MD) concept (MemPower) has been developed for the simultaneous production of high-quality water from various aqueous feedstocks with cogeneration of mechanical power (electricity). Driven by low-grade heat (waste, solar, geothermal, etc.) a pressurized distillate can be produced by operating TNO’s Memstill^® process at high hydraulic pressures. These pressures are theoretically limited by the liquid entry pressure (LEP) of the membrane. The proof of principle has been shown and is based on the transport of water vapor against a hydraulic pressure gradient. Various commercially available membranes have been evaluated in order to obtain high yields in water flux and power densities. Power densities have been measured which are sufficient to drive the pumps in MD. This allows standalone Memstill^® units without electricity consumption to be possible, which are fully driven by waste heat. The application of new incompressible hydrophobic membranes, combining a high permeance with a high LEP, will allow for much higher power densities.

Keywords:

• Low-grade heat
• Waste heat
• Solar
• Desalination
• Drinking water
• Heat–water networks
• Power
• Liquid entry pressure
• Membrane distillation
• High pressure

Notes

Presented at the Conference on Desalination for the Environment: Clean Water and Energy 11–15 May 2014, Limassol, Cyprus