Nanofiltration pretreatment as CO2 deaerator of desalination feed: CO2 release reduction in MSF distillers

In this work, the influence of nanofiltration on carbon dioxide (CO2) release in MSF distillers was investigated for different feed water composition for once-through (OT) and brine recycle (BR) MSF distillers. The results were calculated for the CO2 release from two 20-stage reference MSF once-through and recycle distillers, by coupling mass transfer with chemical reaction. The CO2 release rates decreased exponentially from the first stage to the last stage. The CO2 release rates increased with increasing top brine temperature (TBT). Nanofiltration can be used as CO2 deaeration system in thermal desalination, the amount of CO2 release, in the first stage, decreased by 100% NF from 425 to 140 kg/h in brine recycle, and from 650 to 210 kg/h in once-through distiller, respectively. The CO2 heat transfer resistances decreased by 100% NF from 5.5 × 10-6 to 2.0 × 10-6 m2 K/W in brine recycle, and from 8.1 × 10-6 to 3.0 × 10-6 m2 K/W in once-through distiller, respectively.