Thermodynamic Limitations and Exergy Analysis of Brackish Water Reverse Osmosis Desalination Process.

Alanood Alsarayreh,Alejandro Ruiz-García,Iqbal Mujtaba,Raj Patel,Mudhar Al-Obaidi

doi:10.3390/membranes12010011

Alanood Alsarayreh, Alejandro Ruiz-García + Show 3 more

Open Access

https://doi.org/10.3390/membranes12010011

Copy DOI

Abstract

The reverse osmosis (RO) process is one of the most popular membrane technologies for the generation of freshwater from seawater and brackish water resources. An industrial scale RO desalination consumes a considerable amount of energy due to the exergy destruction in several units of the process. To mitigate these limitations, several colleagues focused on delivering feasible options to resolve these issues. Most importantly, the intention was to specify the most units responsible for dissipating energy. However, in the literature, no research has been done on the analysis of exergy losses and thermodynamic limitations of the RO system of the Arab Potash Company (APC). Specifically, the RO system of the APC is designed as a medium-sized, multistage, multi pass spiral wound brackish water RO desalination plant with a capacity of 1200 m3/day. Therefore, this paper intends to fill this gap and critically investigate the distribution of exergy destruction by incorporating both physical and chemical exergies of several units and compartments of the RO system. To carry out this study, a sub-model of exergy analysis was collected from the open literature and embedded into the original RO model developed by the authors of this study. The simulation results explored the most sections that cause the highest energy destruction. Specifically, it is confirmed that the major exergy destruction happens in the product stream with 95.8% of the total exergy input. However, the lowest exergy destruction happens in the mixing location of permeate of the first pass of RO desalination system with 62.28% of the total exergy input.

Highlights

Due to the scarcity of freshwater resources, the improvement of water desalination technologies is by far the most important target for current researchers aiming to deliver potable water [1,2]
The main desalination technologies are the reverse osmosis (RO) and multi-stage flash (MSF) processes, which account for almost 87% of the total fraction of freshwater produced in the world [3]
This paper focused on the calculation of exergy analysis based on thermodynamic limitations of the multistage multi pass brackish water RO desalination plant of the Arab Potash Company (APC) with a daily production rate of 13.85 kg/s

Summary

Introduction

Due to the scarcity of freshwater resources, the improvement of water desalination technologies is by far the most important target for current researchers aiming to deliver potable water [1,2]. The main desalination technologies are the reverse osmosis (RO) and multi-stage flash (MSF) processes, which account for almost 87% of the total fraction of freshwater produced in the world [3]. The RO process has dominated the membrane technologies due to it producing freshwater at a reduced energy consumption. The simple design of compact size and modularity of RO units and ease of operation at an ambient temperature together with other merits have made the RO process the most popular desalination technology [5,6]. The flexibility in capacity expansion of the RO process with short construction periods, low investment costs and low periodical maintenance enables ease of construction of RO desalination plants of different sizes in the rural areas of water shortage. The performance capacity of the RO process is directly related to the inlet conditions and it varies based on the feed water quality [7], site location and the start-up and shut-off [8,9]

Objectives

Findings

Discussion

Conclusion