TY - JOUR
TI - Influence of nanofiltration pretreatment on scale deposition in multi-stage flash thermal desalination plants
AU - Al-Rawajfeh Aiman E
JN - Thermal Science
PY - 2011
VL - 15
IS - 1
SP - 55
EP - 65
PT - Article
AB - Scale formation represents a major operational problem encountered in thermal  desalination plants. In current installed plants, and to allow for a  reasonable safety margin, sulfate scale deposition limits the top brine  temperature (TBT) in multi-stage flash (MSF) distillers up to 110-112°C. This  has significant effect on the unit capital, operational and water production  cost. In this work, the influence of nanofiltration (NF) pretreatment on the  scale deposition potential and increasing TBT in MSF thermal desalination  plants is modeled on the basis of mass transfer with chemical reaction of  solutes in the brine. Full and partial NF-pretreatment of the feed water were  investigated. TBT can be increased in MSF by increasing the percentage of  NF-treated feed. Full NF pretreatment of the make-up allows TBT in the MSF  plant to be raised up to 175°C in the case of di hybrid NF-MSF and up to  165°C in the case of tri hybrid NF-RO-MSF. The significant scale reduction is  associated with increasing flashing range, unit recovery, unit performance,  and will lead to reduction in heat transfer surface area, pumping power and  therefore, water production cost.