A solution containing 25 per cent by mass of sodium phosphate is cooled from 300 to 290 K in a Swenson-Walker crystallizer to form crystals of Na3PO4.10H2O. The solubility of Na3PO4 at 290 K is 12.5 kg/100 kg water, and the required product rate of crystals is 0.075 kg/s. The mean heat capacity of the solution is 3.5 kJ/kg deg K and the heat of crystallization is 126.5 kJ/kg. If cooling water enters and leaves at 288 and 293 K, respectively, and the overall coefficient of heat transfer is 150 W/m2 deg K, what length of crystallizer is required assuming area available is 1.2 m2 /m length of pipe?

1. A solution containing 25 per cent by mass of sodium phosphate is cooled from 300 to 290 K in a Swenson- Walker crystallizer to form crystals of Na3PO410H20. The solubility of Na3PO4 at 290 K is 12.5 kg/100 kg water, and the required product rate of crystals is 0.075 kg/s. The mean heat capacity of the solution is 3.5 kJ/kg deg K and the heat of crystallization is 126.5 kJ/kg. If cooling water enters and leaves at 288 and 293 K, respectively, and the overall coefficient of heat transfer is 150 W/mdeg K, what length of crystallizer is required assuming area available is 1.2 m/m length of pipe