Selection of the most appropriate type of desalination systems used in sea water.
Supply of fresh sea water is a major solution that can solve the problems of the coastal areas and industries. Being a firm that deals with sophisticated membrane technology, Guangzhou VOCEE realizes that the right choice of seawater desalination system is important. The best alternative will be the one that requires a balanced approach of technical necessities, operational limitations and cost. This guide will explain the major aspects that should be considered when going through the process.
Comparison of Core Technology: Membrane and Thermal.
The main decision point at the core desalination process.
Reverse Osmosis (RO): This is the most common technology that uses membrane. The seawater is pressurized and compelled to pass through semi-permeable RO membranes which prevent salts and impurities. SWRO systems designed today are very energy efficient, modular and scalable. They are generally used as the most preferred option in municipal water supply, industrial applications and in medium and large scale application where the electric energy is easily accessible.
Thermal Desalination (MSF/MED): Multi- Stage Flash (MSF) and Multi- Effect Distillation (MED) are the processes where seawater is heated to create vapors which are condensed into freshwater. These processes are energy-demanding, and may need serious thermal input (e.g. power plant waste heat). They are traditionally strong enough and capable of withstanding water of extremely high salinity, and are hence fit to undertake large scale applications in areas with rich and low-cost thermal energy, including certain Middle Eastern states.
Reverse Osmosis is the improving technology today in most new projects, particularly those that are highly concerned with energy efficiency.
Important Selection Factors: More than the Technology.
When choosing a system, it is necessary to analyze a particular scenario.
Feed Water Quality: The seawater intake is an essential thing. Aspects of salinity, temperature, biological activity, silt and organic content levels all have a direct influence on pre-treatment design and membrane life. A well-developed pre-treatment system; typically ultrafiltration (UF) is necessary in order to prevent RO membranes to be discolored and scaled.
Energy Availability and Cost: This is one of the main cost of operation. High-pressure pumps mostly consume electrical energy in RO systems. Thermal plants need either steam or fuel. The life-cycle cost analysis will strongly depend on the local cost and stability of these sources of energy.
Capacity and Water Quality Requirement: stipulate the daily output requirement and purity level of the product water in the project. RO can be scaled with ease by the addition of membrane modules. In case of applications that require the use of ultrapure water (e.g. as an industrial process), two-pass RO system or incorporation of other polishing technologies might be required.
Footprint and Modularity: RO systems tend to be of a smaller footprint than thermal plants of the same scale. It is also advantageous in that they can easily be expanded in the future, and this is due to their modular character.
The Significance of the System Design.
A desalination plant is not only the principal desalination unit. The pre-treatment and post-treatment selection is its key to success. In the case of RO systems, it is important that the pre-treatment stage occurs efficiently using technologies such as our ultrafiltration membranes in order to eliminate particulates, colloids, and microbes, providing a stable RO process and reducing the number of times it needs to be cleaned. The post-treatment processes are aimed at stabilizing the pH and minerals of the product water to render it stable and palatable.
Making an Informed Decision
No single best system can be found. A large cogeneration plant could need a thermal plant and a remote island or offshore platform would need a containerized SWRO system.
In Guangzhou VOCEE, we use our experience in the area of seawater desalination and ultrafiltration system to not only offer some parts but also solutions. Our technical folks can assist you to determine your particular conditions and develop a system that is efficient, long lasting and the overall cost of ownership. Get in touch with us to see how we will make your seawater a reliable source of freshwater.
