MODELING AND SIMULATION OF MULTIPLE EFFECT EVAPORATOR SYSTEM

Abstract

Concentration of black liquor is economically achieved by use of multi-effect cvaporators. The energy required decreases as the number of effects increases. The present work moves forward to advance a model and an algorithm to design a multiple effect evaporator system. Then, it is needed to determine the extent of steam saved by the use of vapor again. To obtain above targets a model based on equations is refined to design the multiple effect evaporator system of seven - effects to concentrate black liquor. This provides us a thermo- economic solution where in both energy and money will be saved. In the present work initially, a model is developed for simplified model, which is considered as base case for further reference. Then the simplified model is modified to account variation in physical properties, BPR and steam splitting. Further, the developed model is modified to include condensate vapor flashing with various configurations to upgrade tile system economy. For this purpose total eight models are formulated to find out the best. Economic evaluation to optimize the number of flash tanks is carried out for seven effect evaporator system. The SIX different types of configuration of vapor condensate are considered and comparison of among these configurations is done. Considering the optimunl number of flash tanks and the best configuration of vapor condensate flash tanks are designed ..While accounting the maximum possible number of flash tanks, a final SySteill is designed. This modified design enhances the steam economy by 26.1 9% and reduces tile steam consumptioll by 13.48% in comparison to simple system. The comparison between the present model and the published model is carried out and it is observed that the present model ellhances economy and steam coilsuniption by 1 .02% and 1.02% respectively, in comparison to tIle published model. Based on economic analysis system with five flash tanks is selected as optimum and it provides less complex configuration in respect to existing and published configurations.