Through a large number of tests and application examples, it has been proved that the use of
titanium tubes in power station condensers has great technical and economic advantages. Let's talk about the three problems that need to be dealt with when using titanium tubes in power stations. :
1. Corrosion problem
The condenser of coastal power station uses seawater as cooling water. Because seawater contains a lot of sediment, suspended substances, marine organisms and various corrosive substances. The situation is even more severe in brackish water, where the replacement of seawater with river water varies. The traditional corrosion methods of copper and gold tubes are: general corrosion (uniform corrosion), erosion, erosion and stress corrosion. Because titanium has excellent corrosion resistance, the seawater leakage accident caused by corrosion of titanium tube condenser has been eliminated. However, because of the good corrosion resistance of titanium tube, it does not produce a kind of contamination on the surface like copper alloy tube. poisonous substances. Therefore, there are simply sea creatures attached to the inner wall of the titanium tube, which affects the heat transfer effect, so it is necessary to have corresponding cleaning equipment.
2. Hydrogen absorption problem
Although the surface of titanium material has a fine passivation film, it is very resistant to corrosion in many strong corrosive media, but because of the strong affinity of titanium and hydrogen. Very simple to absorb hydrogen. It occurs at room temperature, and it absorbs hydrogen quickly at high temperature (such as 100 °C). The solid melting limit of hydrogen in titanium is very small (about 20ppm), and hydrides (TtH2) will be precipitated on the titanium surface if the limit is exceeded. With the increase of surface TiH2, the impact value and elongation of titanium decreased rapidly. In addition, when the old unit is retrofitted, because the tube sheet is made of copper alloy and the condenser tube is made of titanium, it is necessary to use cathodic protection equipment to avoid electrochemical corrosion. The plate forms a galvanic couple. When the protection potential is lower than -0.75 v (ScE), the titanium tube end of the outlet will absorb hydrogen, and the hydrogen content will reach 650ppm in one year; ), titanium does not absorb hydrogen at room temperature.”
3. The sensational problem
Because the titanium tube has good corrosion resistance. The titanium condenser will not leak and damage due to corrosion. However, the titanium tube may be damaged due to vibration. In order to avoid the vibration problem of titanium tubes, when making titanium condensers, it is necessary to determine the customary partition spacing; when retrofitting old units, it is necessary to check whether the original partition spacing is suitable for titanium welded tubes.
