Vacuum coating machine "emergency stop"?

2019-04-16 14:26  Times of view:

A. the principle of breaking the vacuum can quickly stop

Destroying the vacuum means that the pressure on the exhaust side of the low-pressure cylinder rises rapidly, reducing the sag of the unit, that is, the function is greatly reduced, and the braking effect is exerted. The analogy is that it is a sudden brake, which greatly reduces the idle time of the unit and reduces the possibility of serious damage to the equipment, such as static and static friction, water shock, overspeed, oil system failure and other serious accidents.

Generally, in order to reduce the strong torsional stress and friction blast heat that the final stage of the low-pressure cylinder of the unit is subjected to when the vacuum is broken, it is generally safer to take the vacuum under the rotation speed below 2000 rpm.

B, open the host vacuum break valve is there a speed limit?

In a critical situation, in order to make the turbine rotor accelerate and stop rotating after the turbine trips, the vacuum breaking valve is opened to destroy the condenser vacuum. This will allow cold air to enter the cylinder and increase the blast friction loss, which is equivalent to increasing the braking torque to the rotor, which can reduce the rotor idle time and accelerate the shutdown.

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However, the rotor will also be subjected to a large braking force, which will seriously cause the final stage blades to break. The braking force is related to the rotor speed and the gas density and the gas pressure. The faster the speed, the higher the pressure, the greater the braking force and the more heat generated. In order to limit the force of the blade, the upper limit of the speed of the vacuum break valve is defined to protect the safety of the blade. The Shanghai steam turbine manufacturer requires that the turbine speed be lower than 400 rpm, and the steam turbine has no effect on the turbine. The damage is not big.

C. The steam turbine generator set encounters one of the following conditions, and should stop the furnace at an emergency stop, and the steam turbine destroys the vacuum.

1. When the turbine speed exceeds 3300r/min, the protection is rejected.

2. The turbo generator set suddenly has a strong vibration of more than 0.25mm, and the protection is rejected.

3. When there is a clear metal friction or impact inside the turbine.

4. The axial displacement reaches the limit value (+1.0mm or -1.0mm.) or the thrust bearing metal temperature exceeds the limit.

5. If the lubricating oil supply is interrupted or the oil pressure drops to the limit value (0.06MPa), the standby oil pump is still inactive.

6. The oil level of the lubricating oil tank drops to the limit value (-300mm), and the oil filling is invalid.

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7. Any bearing of the turbine generator set is oil-cut, smoke or any radial bearing metal temperature of 113 ° C, or thrust tile metal temperature of 107 ° C. (except for abnormal points).

8. The turbine has a water impact, and the temperature difference between the upper and lower cylinders exceeds 56 °C. Within 10 minutes, the main and reheat steam temperature dropped sharply by 50 °C, and the extraction pipe entered the water alarm and exceeded the trip value.

9. The turbine shaft seal is abnormally rubbed and sparked.

10. The turbine oil system is on fire and cannot be extinguished very quickly, seriously threatening the safety of the unit.

11. The generator emits smoke, fire, or explosion.

12. All power used in the factory was lost.

D. If the steam turbine generator set encounters one of the following conditions, it shall stop immediately, but it will not damage the vacuum.

1. The operation of the unit has endangered the personal and equipment safety, and must be stopped to avoid personal and equipment accidents.

2. A fire directly threatens the safe operation of the unit.

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3. The important operation monitoring meter or device of the steam turbine is not correct or invalid, and there is no monitoring means.

4. The oil pressure of the turbine EH drops to 8.5 MPa and the protection is not moving or the oil circuit leaks and cannot be isolated.

5. The back pressure of the exhaust unit is greater than 65 kPa.

6. The generator is seriously leaking and jeopardizes safe operation.

7. The generator seal oil system is faulty and cannot be maintained.

8. The generator stator bar temperature difference is 14 °C or the stator water pipe outlet temperature difference is 12 °C, or the temperature of the temperature measuring component in any stator slot exceeds 90 °C or the outlet water temperature exceeds 85 °C.

9. When the hydrogen purity in the generator drops sharply below 92% or the hydrogen pressure drops sharply below the lower limit and cannot be maintained.

10. When the generator slip ring is severely ignited, jeopardizing the safety of the equipment.

11. When the unit is in normal operation, the temperature of the main and reheat steam drops by 50 °C within 10 minutes.

12. When all the operator stations of the thermal control DCS system fail (all operator stations "black screen" or "dead"), and there is no reliable backup operation monitoring means, when it is not possible to recover in a short time.

13. When a main transformer, an excitation transformer, or a high-factor transformer has a serious fault.

14. When the unit trip condition is reached and the protection is rejected.

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