DESIGN PRINCIPLE OF THE NEW SELF-CLEANING EVAPORATORS WITH NATURAL CIRCULATION

The main factors that influence the performance of evaporators are the high energy consumption in the forced circulation pump and thecyclic stop of equipment operation to remove the salt fouling. Theself-cleaning evaporator with natural circulation can solve suchproblems satisfactorily. The driving force of natural circulation is obtained based onthe concept of dynamic temperature and the process of nonequilibriumvaporization. The calculating model isused to effectively enlarge the drivingforce of natural circulation. The boiling chamber is designed with large cross-sectionand depth and gradually increased section at outlet in orderto increase the vaporization equilibrium and reduce the kinetic energy lossat outlet. The heat transfer tubes in the heating chamber must be short, inwhich twisted strip inserts with oblique teeth are installed to efficiently remove salt fouling automatically and to enhance heattransfer with low flow resistance at low fluid flowing velocity, so that thedynamic temperature is raised and the overall resistance of naturalcirculation is lowered. The industrial experiments of such new evaporators havebeen successful.