Quasi-steady state simulations of thermal vapor compression multi-effect distillation plants coupled to parabolic trough solar thermal power plants

Abstract

The evaluation of the coupling of a 50 MWe parabolic trough solar thermal power plant (PT-STP) and a 10,000 m3/d multi-effect distillation plant with thermal vapor compression (MED-TVC) was performed. To that end, a model for the entire system has been developed and implemented within Engineering Equation Solver (EES) and Matlab software environments. Two coupling arrangements between the PT-STP plant and the MED-TVC unit were selected: one taking low-pressure steam (at 1.224 bar) from the power block to feed the MED-TVC and the other one taking high-pressure steam (at 20.6 bar), and the simulations of the electricity and fresh water production of the PT-STP + MED-TVC plant to be located in Spain were carried out during three days in summer (21–23 June) and three days in winter (21–23 December). Results obtained showed that the use of the low-pressure steam to feed the MED-TVC plant reduces the electricity penalization compared with the use of high-pressure steam but also decreases the fresh water production. Since in Spain the electricity demand is lower in summer than in winter, and the contrary occurs with the fresh water demand, the optimum coupling arrangement in summer was using high-pressure steam to feed the MED-TVC (enough steam available in the turbines) and that one in winter was to feed the MED-TVC with low-pressure steam having the lower electricity penalization at the cost of the decrease of the fresh water production.