Why Use Titanium in Desalination Plants?
Desalination plants play a vital role in providing fresh water by removing salt and impurities from seawater. As salt water is harsh and corrosive, the materials used in these plants must be able to withstand the extreme conditions. Common desalination materials available on the market today include metallic materials, polymeric materials, ceramic materials and composite materials. Among these, metallic materials are currently mainly stainless steel, Titanium Alloys and nickel-based alloys, which are widely used in various equipment and components as follows:
1.Stainless steel material
Advantages: good corrosion resistance, high strength and hardness, and relatively low cost, good processing performance.
Applied: In the desalination equipment, stainless steel is often used to manufacture some non-critical and relatively low corrosion resistance requirements of the components. Such as seawater desalination pretreatment system in the pipeline, valves, pump shells and so on. In reverse osmosis desalination equipment, stainless steel can be used to manufacture part of the shell structure and some supporting framework. In the low temperature multi-effect distillation desalination equipment, stainless steel can be used for some auxiliary equipment and non-contact high temperature, high salt concentration area parts.
Benefits: Excellent corrosion resistance, particularly to chloride ions, good resistance to stress corrosion cracking, good temperature resistance, good biocompatibility, high strength to weight ratio.
Uses: It is widely used in seawater desalination plants. In the multi-stage flash and multi-effect distillation desalination equipment, titanium is widely used in the manufacture of evaporator, condenser, heat exchanger heat transfer tubes and tube sheets and other key components, can withstand high temperature, high salinity seawater corrosion, to ensure the efficient operation of the equipment. In the reverse osmosis desalination system, titanium can be used for the manufacture of high-pressure pump impellers, shafts and other key components, as well as reverse osmosis membrane module shell or support structure, to improve the corrosion resistance and service life of the equipment. In addition, in the seawater intake system, titanium pipes and valves can also effectively resist the corrosion of seawater to ensure the stable operation of the system.
3.Nickel based alloy materials.
Advantages: excellent corrosion resistance, especially at high temperature, high concentration of salt solution and strong corrosive media performance, at the same time has a good high temperature resistance and mechanical properties.
Uses: In the desalination industry, nickel-based alloys are mainly used in some key parts that require high corrosion resistance and high temperature resistance. In multi-stage flash evaporation and multi-effect distillation desalination plants, nickel-based alloys can be used to manufacture the high-temperature section of the evaporator, condenser and other components that can withstand higher temperatures and more demanding corrosive environments. In some large-scale desalination plants using thermal desalination process, nickel-based alloys are often used in the manufacture of high-temperature steam and concentrated brine in direct contact with the components, such as heating tube bundles, steam distributors, etc., to ensure that the equipment in the long-term operation of the process of reliability and stability. In addition, in some special desalination process or equipment, such as the treatment of high sulfur, high chlorine and other special water quality desalination equipment, nickel-based alloys can also play its excellent corrosion resistance advantage to ensure the normal operation of the equipment.
ProX Metal is a stable and reliable manufacturer of pure titanium and titanium alloy, specialising in high performance titanium and Titanium Alloy Sheet, bar and tube solutions for desalination and offshore projects, and is ISO9001 certified. With an annual production capacity of 8,000 tonnes of pure Titanium Sheets, rods and tubes, ProX Metal supports customised requirements and has a long history of supplying stable products to high-end customers in China,which is committed to advancing marine and desalination products with leading technology, reliable quality and sustainable development at its core. Titanium alloy grades used for seawater desalination must consider factors such as corrosion resistance, strength, machinability, etc.
Below are some common titanium grades and their characteristics:
①Grade 2 Titanium Materials.
Characteristics: Industrial pure titanium, with good corrosion resistance, weldability and processing performance, relatively low strength, but can meet the requirements of general desalination equipment, the cost is relatively low.
Applications: Widely used in desalination equipment with high corrosion resistance requirements but not much strength, such as seawater pipelines, heat exchanger shells and other titanium pipes, titanium plates.
②Grade 7 (Titanium Ti-Pd).
Characteristics: Palladium is added on the basis of industrial pure titanium, the corrosion resistance, especially crevice corrosion and pitting corrosion resistance, is significantly improved, while maintaining good processing performance.
Applications: It is suitable for the parts of desalination equipment that are prone to crevice corrosion and pitting, such as titanium tube sheet, titanium gasket, etc.
③Grade5 Titanium.
Characteristics: It is an α + β type titanium alloy with high strength, good toughness and fatigue resistance, and good corrosion resistance. Its strength is much higher than that of industrial pure titanium, and it can withstand higher pressures and stresses.
Applications: Commonly used in desalination equipment in the key stress components, such as high-pressure pump impeller, shafts and other titanium bars, but also used in the manufacture of some of the need to withstand the greater pressure of vessels and structural components, such as titanium plate, titanium pipe and so on.
Application Successful Case.
1.Domestic projects
Xisha Yongxing Island Desalination Plant: In June 1981, a multi-stage flash desalination plant with a daily capacity of 200 cubic metres of fresh water was built on Yongxing Island in Xisha.The heat dissipation area used titanium welded tubes with specifications of φ16mm×0.6mm×18400mm. When production was stopped for overhaul in 1999, the carbon steel spacer in the middle of the titanium tubes was badly corroded, but the titanium tubes were still in good condition.
Tianjin Dagang Power Plant Desalination Unit: In 1987, Tianjin Dagang Power Plant introduced two sets of 3000 cubic metres/day multi-stage flash desalination unit, and the heat exchanger used titanium welded tubes of φ16mm×0.6mm×18400mm. The plant is divided into 10 sections with 10 column tube heat exchangers, and the 10 heat exchangers share 2200 imported φ19mm×0.5mm×4220mm titanium welded tubes weighing 1.25 tonnes.
2.Overseas projects.
Matsushima Carbon Mining Co., Ltd. desalination plant in Japan: Built in 1967, the 2,650 tons/day desalination plant uses titanium for heat transfer tubes and plates of the ventilated condenser and jet compressor, and no corrosion failure has occurred after the tubes were replaced with titanium.
Desalination plant built by Japan for Saudi Arabia: A Japanese company constructed 10 units of a distillation desalination plant for Saudi Arabia with a daily production capacity of 30,000 tonnes of fresh water, using 3,200 tonnes of titanium tubes.
If you have any needs or issues relating to titanium, ProX Metal's professional sales and technical team will actively discuss them with you. Feel free to contact us at any time. Email: info@proxtitanium.com.
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