DYNAMIC BEHAVIOR OF MSF DESALINATION PLANTS

This paper describes the development of a computer simulation program to predict the performance of multistage flash (MSF) plant systems under transient conditions. The model developed is based on coupling the dynamic equations of mass energy and momentum. These equations describe the dynamic behavior of brine and product streams within the flashing stages. The effect of salinity and temperature variation on the specific heat, boiling point elevation, enthalpy and density is accounted for in this model. The model consists of six differential equations and three algebraic equations describing the dynamic behavior of each stage in terms of the following variables: inlet feed temperature, brine temperature, product temperature, brine level, product level, brine salt concentration, outlet product flow rate, outlet brine flow rate and vaporization rate. The results obtained are useful for dynamic parametric studies and for the prediction of the performance of a given plant under a wide range of possible transient conditions. A case study of a step increase in feed water temperature is investigated, and sample results are illustrated.