From an economic point of view, the price of a titanium tube for a 1000Mw condenser nuclear power unit (about 50,000 condenser tubes is required) is taken as an example. According to the use time of the condenser for 40 years, the average aluminum brass tube There are 10 leaks per year, and the titanium tube has no leaks within 40 years. 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. Here are three problems to be solved when titanium tubes are used in power stations :
1. Corrosion issues
The condenser of the power station uses seawater as cooling water. Because seawater contains a large amount of sediment, suspended matter, marine life, and various corrosive substances. The situation is more serious in brackish water where seawater and river water alternately change. Traditionally used corrosion methods of copper-plated gold tubes are comprehensive corrosion (uniform corrosion), erosion, erosion, and stress corrosion. Because titanium has excellent corrosion resistance, the seawater leakage accidents caused by corrosion of titanium tube condensers have been Eliminate, however, because of the good corrosion resistance of titanium tubes, unlike copper alloy tubes, a toxic substance is not produced on the surface. Therefore, it is easy for sea creatures to adhere to the inner wall of the titanium tube, which affects the heat transfer effect, so it must be There is a corresponding cleaning device.
2. The problem of hydrogen absorption
Although the surface of the titanium material has a dense passivation film, it is very resistant to corrosion in many strong corrosive media, but due to the large affinity of titanium and hydrogen. It is very easy to absorb hydrogen. It occurs at normal temperature and at high temperature (such as 100 ℃) Absorb hydrogen quickly. The solid melting limit of hydrogen in titanium is very small (about 20ppm). If it exceeds the limit, hydride (TtH2) will be precipitated on the titanium surface. With the increase of the surface TiH2, the impact value and elongation of titanium decrease rapidly. In addition, during the transformation of the old unit, because the tube sheet is a copper alloy, the condenser tube is made of titanium, which requires the use of a cathodic protection device to prevent electrochemical corrosion. For example, the condenser of Hitachi Power Plant uses seawater cooling, and the titanium tube and copper alloy The plates form a galvanic couple. When the protection potential is lower than 0.75 v (ScE), the titanium end of the outlet absorbs hydrogen. The hydrogen content reaches 650 ppm in one year; if the potential is selected from 0.5 to O.75 v (scE), the Titanium will not absorb hydrogen at room temperature "
3. Vibration problem
Due to the good corrosion resistance of the titanium tube, the titanium condenser will not be damaged due to corrosion, but the titanium tube may be damaged due to vibration. To avoid the vibration problem of the titanium tube, when manufacturing the barrier titanium condenser, Therefore, it is necessary to determine the adaptable spacer spacing; when retrofitting an old unit, it is necessary to check whether the original spacer spacing is suitable for titanium tubes.
grade 36 titanium rod titanium foil titanium metric screw grade 23 titanium plate
1. Corrosion issues
The condenser of the power station uses seawater as cooling water. Because seawater contains a large amount of sediment, suspended matter, marine life, and various corrosive substances. The situation is more serious in brackish water where seawater and river water alternately change. Traditionally used corrosion methods of copper-plated gold tubes are comprehensive corrosion (uniform corrosion), erosion, erosion, and stress corrosion. Because titanium has excellent corrosion resistance, the seawater leakage accidents caused by corrosion of titanium tube condensers have been Eliminate, however, because of the good corrosion resistance of titanium tubes, unlike copper alloy tubes, a toxic substance is not produced on the surface. Therefore, it is easy for sea creatures to adhere to the inner wall of the titanium tube, which affects the heat transfer effect, so it must be There is a corresponding cleaning device.
2. The problem of hydrogen absorption
Although the surface of the titanium material has a dense passivation film, it is very resistant to corrosion in many strong corrosive media, but due to the large affinity of titanium and hydrogen. It is very easy to absorb hydrogen. It occurs at normal temperature and at high temperature (such as 100 ℃) Absorb hydrogen quickly. The solid melting limit of hydrogen in titanium is very small (about 20ppm). If it exceeds the limit, hydride (TtH2) will be precipitated on the titanium surface. With the increase of the surface TiH2, the impact value and elongation of titanium decrease rapidly. In addition, during the transformation of the old unit, because the tube sheet is a copper alloy, the condenser tube is made of titanium, which requires the use of a cathodic protection device to prevent electrochemical corrosion. For example, the condenser of Hitachi Power Plant uses seawater cooling, and the titanium tube and copper alloy The plates form a galvanic couple. When the protection potential is lower than 0.75 v (ScE), the titanium end of the outlet absorbs hydrogen. The hydrogen content reaches 650 ppm in one year; if the potential is selected from 0.5 to O.75 v (scE), the Titanium will not absorb hydrogen at room temperature "
3. Vibration problem
Due to the good corrosion resistance of the titanium tube, the titanium condenser will not be damaged due to corrosion, but the titanium tube may be damaged due to vibration. To avoid the vibration problem of the titanium tube, when manufacturing the barrier titanium condenser, Therefore, it is necessary to determine the adaptable spacer spacing; when retrofitting an old unit, it is necessary to check whether the original spacer spacing is suitable for titanium tubes.
grade 36 titanium rod titanium foil titanium metric screw grade 23 titanium plate
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