Discuss the factors that affect the vacuum in steam turbines.
Thread Content
Let’s discuss the factors that affect the vacuum in steam turbines; anything related will count. Those who provide more answers will receive a generous reward.
The sealed steam pressure is low and the flow rate is small
Air leaks in through various negative pressure pipelines, joints, and sealing points； The cooling water flow rate of the condenser decreases, its temperature rises, the thermal resistance increases, resulting in poor heat transfer efficiency ； The jet ejector performs poorly (clogging of nozzles, poor heat exchange efficiency, etc.) ； The measurement of water accumulation in the pipeline is inaccurate ； The hot well level is too high ； The unit load is too high ； I’ve run into this problem too and am still thinking about how to solve it.
When the vacuum level drops, the following factors are involved； An increase in steam flow can not only cause overload of the final stage blades, but also increase the axial thrust of the turbine unit; in severe cases, this can damage the thrust bearings, directly affecting the safety of the unit. When the vacuum drops too much, causing the exhaust temperature to rise significantly, it leads to uneven deformation of the exhaust cylinder, resulting in a shift in the center of the bearing shells. This induces substantial vibrations, which can damage the seal integrity of the copper tubes in the condenser, having a significant impact on economic operation. When the vacuum in the condenser drops to 0.12 absolute atmospheres, load reduction should begin ； When the vacuum drops to 0.2 absolute atmospheres, the load should be reduced to zero ； When the vacuum continues to drop to 0.3 absolute atmospheres, the machine should be shut down by tripping the breaker.
1. There are leakage points in the vacuum system； 2. Internal leakage in the condenser ； 3. There is a problem with the water jet pump or vacuum extractor ； 4. Excessively high hot well liquid level ； 5. Excessively high circulating water temperature 6. Condenser blockage ； 7. Interruption of the condenser circulating water flow. 8. Insufficient steam supply to the turbine shaft seal or interruption in pressure ； 9. Air entry in the hot well make-up water pipeline