OPTIMIZATION OF MULTIPLE EFFECT EVAPORATOR SYSTEM BASED ON DIFFERENT CONFIGURATIONS OF VAPOR BLEEDING

Abstract

This work reports on advancement of a model and an algorithm to design a multiple effect evaporator system. Then, it is needed to determine the extent of savings of steam using vapour bleeding. To obtain above targets different models based on non-linear equations are developed to design the multiple effect evaporator system to concentrate black liquor. For 1st part 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, model developed in second part is modified to include vapor bleeding with different configurations such as steam splitting, configuration 1 and 2 for system with vapor bleeding, considering vapor bled from vapor generated in second effect, third, fourth, fifth and preheating of liquor using condensate in seven effect evaporator system and steam splitting model and vapor bleeding in ten effect system. In the present work two MEE systems such as seven effect and ten effect evaporator systems are considered to concentrate black liquor solution. In the present work, the best and published models are developed for seven and ten, respectively, effect evaporator system. These are compared based on steam economy. For seven effect evaporator system, Mod-9 model which considers preheating of liquor using condensate is found as best. This model enhances the steam economy of the system by 7.151% in comparison to published model. However, for ten effect evaporator system, Mod-11 which incorporates vapor bleeding is found as best, which increases the steam economy of the system by 4.34%. Further, comparison between the published model and the best model is done for seven effect evaporator system. For the best model steam economy is 5.999 and steam consumption is 2.097 kg/s. However, for published model steam economy and steam consumption is 5.570 and 2.138 kg/s, respectively. As the economy and steam consumption of the best model is 7.151% more than the steam economy and 1.917 % less steam consumption in