During the operation of the generator, there is energy consumption. These energies become heat energy. If no cooling measures are taken, the temperature of the rotor, stator and other components will rise, which will lead to aging of the insulation winding, the output will drop, and even burn the motor.
Regardless of the capacity of the generator, the stator windings are generally cooled by water, some of the rotor windings are cooled by water, and some are cooled by air. Water cooling is to make the winding copper coil hollow. During operation, high-purity water passes through the inside of the copper tube to bring out heat. The cooling water from the generator returns to the water tank, which is then pumped out through the cooler to cool, and then enters the generator. Inside, recycle.
Since the generator cooling water is used as a cooling medium in a high-voltage electric field, the water quality is high. Compared with ordinary cooling water, in addition to meeting the requirements of non-corrosion and non-fouling, it must also have good electrical insulation properties.
At present, the circulating water technology of power plants has become increasingly mature. The generator cooling water is generally not required to be sterilized or scale inhibited because of its small amount of water, high purity of water, and low tendency to scale. Therefore, it did not attract enough attention, and some factories even relaxed the control standards. However, if the water quality of the generator cooling water does not meet the requirements, long-term operation will have serious consequences.
According to statistics, nearly half of the accidents caused by generators in recent years are related to cooling water. Therefore, its processing technology is very demanding, and pay attention to some problems.
1. The water quality of the generator cooling water is in the power plant, and the supplementary water of the generator cooling water is condensed water or demineralized water, and its water quality is pure. Therefore, what needs to be controlled is the running water quality, and the indicators related to it have conductivity, pH value, and Cu2+ content.
1.1 Conductivity conductivity reflects the amount of ions in the water. When the conductivity is too large, it will cause a large leakage current, which will cause the insulation water conduit to age, causing the generator to flash between phases and even destroy the equipment. As the capacity of the unit increases, the requirements for electrical conductivity are also increasing.
1.2 The pH value is controlled by the internal cooling water to control the pH value to prevent corrosion of the copper wire. From the potential-pH balance diagram analysis, the stable pH range of copper is between 7 and 10, and the pH value of the industrial equipment is controlled at 7.6~9. It is more suitable. In pure water, copper corrosion is generally uniform corrosion, and the probability of damage caused by corrosion perforation is small, but the corrosion product is blocked by the generator magnetic field in the system, and is deposited inside the hollow wire, which reduces the flow area and even causes blockage. The cooling effect is deteriorated, causing the temperature of the bar to rise, which affects the normal operation of the genest.
1.3 Current status of internal cold water quality control In order to ensure that the generator has sufficient electrical insulation performance and small copper corrosion, the national and industry have established corresponding standards (see Table 1). The generator manufacturer puts forward higher requirements for water quality standards. For units with unit capacity of 200MW and above, the actual control conductivity is generally required to be no more than 2 2 within the cold water treatment method and precautions along with the ultra high pressure. The commissioning of the unit and the water quality requirements are also getting higher and higher. Some traditional methods of treatment are no longer sufficient and require constant exploration and innovation.
Using condensed water as supplementary water for internal cold water 2.1.1 Method: In the thermal power plant, adding trace ammonia to the feed water to adjust the pH value to achieve the purpose of anti-corrosion, the volatility of ammonia makes the condensed water pH: 2002 Table 1 The standard of the internal cold water quality of the generator Code Name Standard Value pH Remarks (82) Hydropower Word No. 24 Generator Operation Regulations Thermal Power Generator Sets and Steam Power Equipment Water No Corrosion Inhibitors Steam Quality Standards Add Corrosion Inhibitors Hydropower Plant Water Vapor Quality Supervision Guidelines Without Corrosion The addition of corrosion inhibitor to the thermal power plant water vapor quality standard without corrosion inhibitor added corrosion inhibitor value of about 8.6, the conductivity is 3. 0pS / cm. Inward cold water supplemental condensate is equivalent to the addition of trace ammonia into the cold water In order to increase the pH value for anti-corrosion purposes.
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