Poor local drainage can also lead to excessive vibration during flushing, so you can only stop and warm up again. If there is abnormal cylinder expansion and differential expansion, it is also a locked start-up life. The large temperature difference between the upper and lower cylinders caused by poor drainage is also one of the reasons why the warm-up time is forced to increase. Generally speaking, as long as the drain valve is always open, it is difficult to drain freely because of the vacuum in the condenser. Of course, there is no way to block the drain pipe with garbage.
The main factors affecting differential expansion of steam turbines are as follows.
(1) Whether the sliding pin system of steam turbine is unblocked. During operation, attention should be paid to frequent oiling between sliding surfaces to ensure lubrication and free movement of sliding surfaces. Some units install a thin sliding pad between the bearing box and the sliding surface of the bedplate, which can greatly reduce the friction between the sliding surfaces and ensure the free expansion and contraction of the cylinder. ?
(2) Controlling the temperature rise (temperature drop) of steam and the speed of flow change is an effective method to control the expansion difference, because the fundamental reason of the expansion difference is the temperature difference between the cylinder and the rotor. The temperature rise or flow rate of steam changes rapidly, and the temperature difference between rotor and cylinder is also large, resulting in a large expansion difference. Therefore, in the process of steam turbine startup and shutdown, the expansion difference can be controlled by controlling the changing speed of steam temperature and flow rate.