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 genset.
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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