Superstructure of Alternative Configurations of the Multi Stage Flash Desalination Process

SERGIO MUSSATI,; AGUIRRE, PIO; NICOLAS SCENNA,

INDUSTRIAL & ENGINEERING CHEMICAL RESEARCH

American Chemical Society. Washington, USA.

Año: 2006 vol. 42 p. 7190 - 7203

0888-5885

This paper addresses the optimal synthesis and design of Multi Stage Flash (MSF) evaporator systems. A detailed NLP model based on a superstructure developed previously by Mussati et al. 2003 [1] has been appropriately reformulated in order to include more alternative configurations for the process. The new superstructure includes the number of stages and the stream flow patterns (distillate, feed and discharge brine, extraction points and recycle flow-patterns). So, the superstructure embeds simultaneously an enormous number of alternatives, including of course, the three commonly operating modes for the evaporator: MSF-BR, MSF-M and MSF-OT systems and their combinations which up to date have not been analyzed systematically. Additionally, a rigorous mathematical model by stage and component including also the geometric design of each stage (length, height and width), number of tubes in the pre-heaters, fluid-dynamic equations for the streams among others, is employed. An attractive configuration for the MSF System resulted from the proposed superstructure. This structure differs from the conventional one since it considers distillate extractions, two recycle streams and new allocations for the cooling seawater, blow-down brine and recycle.  The mathematical model and the solution procedure have been implemented in GAMS [2]. Two study cases are presented in order to illustrate the model and solution procedure capabilities. A complete description of the novel configuration, detailed comparison between different “sub-optimal” structures and a sensitivity analysis on the main process variables are summarized.