MED-TVC Parallel Feed Water with Energy Recovery from Brine Preheating

Multi-effect parallel feed desalination system (MED-PF) has emerged as an efficient technology for large-scale seawater desalination. Enhancing the system's performance ratio and incorporation of a thermal vapor compressor (TVC) have proven to be effective in previous studies. Notably, these studies have suggested that the optimal placement for the TVC is within the middle section. The current study explores the impact of a new component, a brine preheater, on the performance of multi-effect desalination system. The hot rejected brine is used to heat the feed seawater for systems with various number of effects. Results demonstrate that utilizing the rejected brine for feed preheating significantly improves the system’s performance ratio among other important parameters. Comparative analysis also shows that utilization of heat associated with the rejected brine for feed preheating leads to a reduction in the cost of water produced in the range of 4.55–9.63%. For example, water production cost of 1.87 $/m 3 for a 8-effect MED-PF system without brine preheating reduces to 1.69 $/m 3 upon preheating the feed without an additional, external energy source. Nevertheless, this approach results in an improvement in the system's performance ratio (PR) in the range of 7.46% to 13.9%. The effect on the total heat transfer surface area (sA) and specific flow rate of cooling water is also taken into consideration.