The use of titanium tubes in MSF desalination plants

Abstract

The use of titanium tubes in MSF desalination plants can eliminate all chances of tube failure throughout the expected life of the plant. Service experience over many years has demonstrated the complete absence of tube failures due to any corrosion or erosion mechanism in power station condensers. This demonstrates completely the suitability of titanium for the heat rejection stage of an MSF plant. This complete freedom from tube failures can also be expected in the higher temperatures and brine concentrations found in the heat recovery and brine heater sections of an MSF plant. To achieve the reliability required attention has to be given to the choice of compatible materials and tube fixing techniques. The mechanisms of crevice corrosion, of galvanic corrosion and of titanium hydriding will be discussed and choice of materials and techniques will be described which will avoid these problems. Titanium's total resistance to erosion can also be used to give a significant improvement in the heat transfer efficiency. This can be simply achieved by increasing the water velocity but can be very much further increased by the use of advanced geometry titanium tube. The choice of appropriate design of advanced geometry titanium tube will be presented together with the effects on the heat transfer coefficients and the pressure drop along the tube.