Integration of a MSF Desalination System with a HDH System for Brine Recovery

A hybrid Multi-Stage Flash-Humidification Dehumidification (MSF-HDH) desalination system is investigated for energy recovery from an MSF system. The hybrid MSF-HDH system increases total productivity and performance ratio and reduces brine rejection. Hot condensed steam that leaves the MSF brine heater is used to warm the rejected pretreated brine from MSF to a higher temperature suitable for HDH system operation (about 60 degrees C). This allows us to increase the product (desalinated water) without additional external energy input to the hybrid system. Four different layouts of the integrated MSF-HDH system are presented and compared. The results show that an HDH system can utilize over 66% of an existing MSF brine blowdown, while the hybrid system can achieve a gained output ratio-GOR, water recovery ratio-RR, productivity and freshwater cost of 8.73, 44.86%, 30,549 m(3)/day and 1.068 $/m(3) of freshwater, respectively. Utilizing 66.96% of MSF brine blowdown by the HDH system leads to a daily HDH productivity of about 670 m(3) of drinking water, which is enough to support 134,000 persons considering a daily consumption of 5 L of drinking water per person.

Automated summary

The study shows that using a hybrid MSF-HDH system can increase freshwater productivity and performance ratio, while reducing brine rejection and decreasing external energy consumption.