Experimental Investigation And Design Of Crystallizer Of Concentrated Seawater

Fresh water was obtained from seawater or brackish water using different methods, but the appropriate way to deal with the damage by the discharged concentrated water have not been found to date. So it is important to seek a proper way to recycle the available resources effectively. This paper designed a set of draft tube baffle crystallizer of concentrated seawater based on the experimental data of the boiling point elevation and evaporated crystallization of seawater in the local sea, and the comparison of the advantages and disadvantages of different type of evaporative crystallizers. Then the experimental study of the evaporative crystallizer was carried out using aqueous ammonium sulphate solution.Experimental investigation on boiling point elevation of seawater in Dalian sea with various concentrations ranging from3%to saturated concentration at different pressures was carried out by atmospheric and vacuum distillation in this paper. The experimental results indicate that the boiling point elevation of seawater in Dalian is higher than the data of seawater in literature. And the boiling point elevation of seawater increases with the system temperature increasing. And also the evaporative crystallization of different solutions including seawater, pretreated seawater and Nacl solution was investigated using evaporative crystallization device of glass. The experimental results show that the medium size of crystal particles at higher evaporation temperature is larger than which at lower evaporation temperature when the heating temperature is fixed. And the crystal particles are better distributed compared with which at lower evaporation temperature. The results also indicate that the shape and appearance of crystal particles have changed for the existence of impurities.The draft tube baffle evaporative crystallizer comprises of crystallizing chamber, separating chamber, elutriation leg, heater and condenser. First the experimental system was assembled and debugged, and then the pressure drop of heater was investigated using ammonium sulphate. And the type of heater applied to the experimental system was compared, the results show that horizontal heater is more appropriate. And the medium size of crystals obtained from the evaporative crystallizer is larger than0.39mm, which shows that the elutriation of the evaporative crystallizer is effective. After comparing the experimental results at different pressures we found that the evaporative crystallizer operated better when the pressure of the experimental system controlled at20kPa.