Hybrid Membrane Distillation and Wet Scrubber for Simultaneous Recovery of Heat and Water from Flue Gas

Abstract

Flue gas contains high amount of low-grade heat and water vapor that are attractive for recovery. This study assesses performance of a hybrid of water scrubber and membrane distillation (MD) to recover both heat and water from a simulated flue gas. The former help to condense the water vapor to form a hot liquid flow which later used as the feed for the MD unit. The system simultaneously recovers water and heat through the MD permeate. Results show that the system performance is dictated by the MD performance since most heat and water can be recovered by the scrubber unit. The scrubber achieved nearly complete water and heat recovery because the flue gas flows were supersaturated with steam condensed in the water scrubber unit. The recovered water and heat in the scrubber contains in the hot liquid used as the feed for the MD unit. The MD performance is affected by both the temperature and the flow rate of the flue gas. The MD fluxes increases at higher flue gas temperatures and higher flow rates because of higher enthalpy of the flue gas inputs. The maximum obtained water and heat fluxes of 12 kg m−2 h−1 and 2505 kJm−2 h−1 respectively, obtained at flue gas temperature of 99 °C and at flow rate of 5.56 L min−1. The MD flux was also found stable over the testing period at this optimum condition. Further study on assessing a more realistic flue gas composition is required to capture complexity of the process, particularly to address the impacts of particulates and acid gases.

The Water Flux Dynamic in a Hybrid Forward Osmosis-Membrane Distillation for Produced Water Treatment

“…The pure water permeability coefficient, the solute permeability coefficient and the structural parameter of the applied membrane were 5.36 L m −2 h −1 bar −1 , 0.95 L m −2 h −1 and 0.265 mm, respectively as reported elsewhere [ 38 ]. In contrast, the PTFE membrane used for MD operation possess hydrophobic properties of 138° contact angle, pore size of 0.22 µm, thickness of 175 µm and 70% of membrane porosity as reported in our earlier report [ 28 ].…”

“…The FO unit in the hybrid FO–MD system is expected to serve as a low-cost and high-efficiency pretreatment for MD to remove the substances from feed solution that potentially cause wetting while offering a great solution to membrane fouling in MD [ 26 ], since MD is only involve in treating sole draw solutes from FO [ 27 ]. At the same time, MD also shows great potential for small-scale wastewater reclamation, decentralized systems with available waste heat source [ 2 ], as well as for waste heat recovery from the flue gas [ 28 ].…”

Process intensification in the fields to separate, recycle and reuse waste through membrane technology

“…Mohd Hizami Mohd Yusoff et al intensified the membrane distillation (MD) process by combining it with a wet scrubber (WS). 72 The MD + WS system simultaneously…”

“…Mohd Hizami Mohd Yusoff et al intensified the membrane distillation (MD) process by combining it with a wet scrubber (WS). 72 The MD + WS system simultaneously recovered water and heat through the MD permeate using polytetrafluoroethylene (PTFE) as the membrane polymer. The scrubber achieved complete water and heat recovery.…”

Membrane distillation: recent technological developments and advancements in membrane materials

“…-Coupling of wet scrubber and integration with MD [67] -Cooling the gas using humidifier followed by hydrophobic membrane condenser [68,69] emergent mater.…”