Power plant and seawater cooling and protection

Power plant condensers cooled with seawater implement forced current internal cathodic protection. Ten new technologies under development in recent years. The following is an application example of emergency protection inside a large condenser with copper tubes and aluminum alloy tubes. This is a one-way tube bundle heat exchanger without shunts, with a box-type header, each power station needs two such condensers; the surface area of the steel box-type header with anti-corrosion layer that needs to be protected is 65m2; pipes, inlets There is a total of 20m2 with the surface of the outlet part; the cooling water of 30-40 temperature flows through the condenser. Cathodic protection is required for the internal corrosion protection of steel box headers with anti-corrosion layer, and it is also to prevent bimetallic corrosion between steel and copper-aluminum pipeline materials.

Cathodic protection protection scope: water chamber inner wall, tube sheet, tube end.

The cathodic protection of the inner wall of the condenser of the power plant can be an impressed current or sacrificial anode cathodic protection system. For condensers that require a long protection period and high water quality and conductivity, the impressed current cathodic protection system should be adopted. At present, most power plants use impressed current. , Sacrificial anode cathodic protection system can be used for those with good anti-corrosion layer, short protection period and low water conductivity.

The advantages of using impressed current cathodic protection are as follows:

1. The impressed current cathodic protection can provide continuously adjustable protection current, so that the various materials in the water chamber can reach the protection potential as a whole, provide sufficient protection, and eliminate galvanic corrosion.

2. The main protection objects of the inner wall of the condenser are the tube sheet, the pipe section, the water chamber, and the inlet and outlet pipes of other materials are also connected. The potential difference caused by different materials and the galvanic corrosion of dissimilar metals, the drive provided by the sacrificial anode The voltage is very low, only the sacrificial anode is difficult to eliminate the dissimilar metal galvanic corrosion, and it is difficult to control the protection current.

3. The cathodic protection power supply can monitor the effect of cathodic protection in real time, which is extremely critical to ensure the life of the condenser.

4. For later maintenance, the sacrificial anode method needs to be replaced regularly, which increases maintenance and construction costs. Impressed current requires a large one-time investment, but it is more cost-effective in the long run.

In summary, for the cathodic protection of condensers, the impressed current cathode system is better than the sacrificial anode system.

Cathodic protection is also widely used in power plants to protect cooling water diversion pipeline systems, circulating water pipes, circulating water pumps, various buried pipelines and related equipment, and water intake fences in water intake pump houses for protecting water sources.