Optimization of multistage flash desalination process by using a two-level factorial design

Optimization of operating variables in a multistage flash desalination plant is useful as it leads to an increase in distillate production rates, and better plant performance with less brine discharged to the sea, and lower operating costs. In this paper, a 2^k factorial experiment is performed to ascertain the effect of five factors and their cross-influence on the blow down flow and the production of the unit at different situation. The factors include sea water temperature, temperature difference, last stage level, first stage level, and brine recycle pump flow. The results from the experiment suggest that brine recycle pump flow, the interaction between the last stage level and first stage level, sea water temperature and last stage level, sea water temperature and temperature difference and brine recycle pump flow, in addition to temperature difference, last stage level, and first stage level are all significant with different degrees of importance. The results have shown also that last stage level has the most pronounced effect on the blow down flow followed by the first stage level and by the interaction between sea water temperature and last stage level. The optimal value with specified desirability was calculated and presented.