Experimental Basis And Process Simulation Of Multi-effect Evaporation

In this work, VLE experimental device was designed and the water and 10% NaCl solution were chose to do the experiments, the feasibility of detecting bubble point of salt solution by experimental device in a certain pressure and concentration were investigated. Based on this experiment, experiments of different concentrations of sodium chloride solution, calcium chloride, ammonium sulfate and mixed salt solution were carried out. The results show that with the increase of the concentration of sodium chloride solution, bubble point also increase in a certain pressure,and with the increase of the pressure, bubble point of sodium chloride solution also increase in the same concentration. And with the increase of the concentration of mixed salt solution of sodium chloride and calcium chloride, bubble point of mixed salt solution also increase in the same pressure,and with the increase of the pressure, bubble point of mixed salt solution also increase in the same concentration. At the same time, phase equilibrium relationship of concentration, pressure and bubble point is obtained, which provides a useful reference for multi-effect evaporation operation and simulation of salt solution and mixed salt solution.In this study, based on evaporator of the heating at outside, multi-effect evaporation of water vapor system was simulated for chemical process with PRO II software, for example, three-effect downstream evaporation process, three-effect four-evaporator process, three-effect countercurrent evaporation process, three-effect countercurrent evaporation process with pre-heating,and effects of different multi-effect evaporation process and pre-heating on the steam economy were studied. It was found that the best operation for economic steam consumption is three-effect countercurrent operation in the former three different multi-effect evaporation process, and steam economy of three-effect downstream evaporation process is higher than three-effect four-evaporator. And steam economy with pre-heating is better than without pre-heating in three-effect countercurrent evaporation process.