Brine Management: Techno-economic Analysis of a Mechanical Vapor Compression Energy System for a Near-Zero Liquid Discharge Application

Abstract

Fresh water availability is gradually decreasing and may limit the primary needs of drinking water and irrigation, as well as other activities, such as energy conversion, tourism, etc. A high number of desalination plants are being built to provide clean water. One of the main strategies is the brine volume minimization by means of either membrane or thermal processes. The present study focuses on the development of a techno-economic analysis of a Single Effect-Mechanical Vapor Compression (SE-MVC) system for purposes of brine volume minimization. The aim is to evaluate the thermodynamic and economic performances as well as the capital and operating expenditures of the brine concentrator when being part of a near zero liquid discharge (near-ZLD) application. This is achieved by developing the thermodynamic and economic models of the system, which are then combined together in a single integrated procedure. Brackish water analysis is used as starting point for this work. Water properties are modeled using Pitzer's equations as well as correlations found in the literature. The economic evaluation of the investment is performed by calculating the Net Present Value and Internal Rate of Return, key parameters to assess the investment viability of the project. The evaporator model provides the necessary input variables for the economic model. For a feed flow of 10.147 kg∙s-1 and a heat duty of 18080 kW, the annualized capital cost of equipment is 594.93 k€∙y-1, while the operating expenses are 854.40 k€∙y-1 The total annualized cost of the process is 1449.33 k€∙y-1.