Why Titanium is the Best Material for Seawater Desalination?

Why Titanium is the Best Material for Seawater Desalination?

Titanium is the best material to resist the corrosion performance of seawater at room temperature, and it has excellent corrosion resistance even in polluted seawater, hot seawater (less than 120 °C), sea mud and flowing seawater. Its excellent corrosion resistance is ascribed to good self-passivation. The surface oxide film or passivation film can quickly repair and restore itself when titanium is subjected to some degree of damage. Titanium surface can form a strong adhesion and tough oxide film in marine media. So its corrosion resistance is more than other metals. According to the existing desalination project, even if the flow rate of water is 10 m-s, the titanium tube will not appear any denudation, cavitation, or impact corrosion. In addition, in titanium SD equipment with the flow rate of water 3~5 m s-1, the phenomenon of biological fouling is the slightest. It is well proven to be reliable that the world's millions of meters of titanium tubes are used in desalination projects.

Titanium tubes have a longer service life in usage performance. The seawater is often mixed with sediment and sea creatures, which easily attach to the heat transfer tube and the end of the pipe. This will erode the copper alloy pipe. However, titanium pipe will not appear this problem. In particular, when oxygen has to be injected to kill bacteria in seawater, it is necessary to use titanium tubes with good corrosion resistance.

Although the thermal conductivity of titanium is not high, the type of heat transfer between surface and steam is droplet condensation. The heat transfer pipe is a small-calibre circular tube. The copper alloy pipe and other wall thicknesses are generally 0.9~1.2 mm under the premise of satisfying the strength. By reducing the thickness of the thin wall of the pipe, the thermal resistance can be reduced. The wall thickness of titanium pipe is much thinner and has higher thermal conductivity compared to B30 copper. For the titanium pipe, it can not only save costs but also improve the heat exchange coefficient. At the same time, because the heat transfer model of titanium pipe surface and steam is drip condensation, the thermal resistance is reduced, and the heat transfer performance of titanium is significantly improved.