Techno-economic assessment of boiler feed water production by membrane distillation with reuse of thermal waste energy from cooling water

Abstract

The European KIC-Climate project Water and Energy for Climate Change (WE4CC) aims at the technical demonstration, business case evaluation and implementation of new value chains for the production of high-quality water using low-grade thermal waste energy from cooling water. A typical large-scale waste heat water network is the production of the boiler feed water from surface water using waste heat of temperatures below 60°C from power plants. Two innovative membrane distillation concepts for the production of high-quality water were evaluated for this case in terms of operational conditions, equipment size and costs which are dependent on the available amount of waste heat and its temperature.• Memstill® (partial use of waste heat, by partially cooling down cooling water such that the remaining heat can be reused for other applications, e.g. for the recovery of desiccant solutions)• MD-HEX, i.e. membrane distillation with an extra integrated heat envelope within the Memstill® module for full use of waste heat which is taken up by the produced water and/or the concentrate.Both Memstill® and MD-HEX behave as a demineralised water (demi-water) producing once-through cooler. Due to the utilisation of waste heat, much less electricity is needed for the production of demi-water relative to other water production technologies. Memstill® also behaves as a waste heat-consuming demi-water producing technology. Thus, significant reductions in cooling water intake, costs and GHG emissions can be achieved.