Question for help: The speed of the small turbine only reaches 1800 r/min and cannot go any higher
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The B0.32--0.9/0.15 type small turbine in our plant was used to drive the DG85-80*10 feed water pump, but it stopped operating due to excessive vibration. The steam seal ring and bearing shells were replaced. During the trial run, the speed could not be increased beyond 1800 r/min. Currently, the main steam valve, control steam valves, and the isolation valve in front of the main steam valve have all been checked and show no problems. There is good vibration during rotation, with no obvious frictional noises. The steam parameters are acceptable. I’d like to ask the experts: what exactly is the problem?
1. Is the backpressure vacuum level normal? 2. Is the oil pressure of the hydraulic actuator normal? 3. Has the lubricating oil been cleaned? 4. Is the steam pressure normal? There’s one more thing I didn’t want to ask – after all, these are machines that have undergone major repairs – but you said the quality of the steam is acceptable... Poor steam quality can cause scaling on the turbine blades.....:L
The back pressure has been relieved; no vacuum is involved. The blades have a small amount of buildup, but this should not affect a speed of nearly 1200 r/min. The steam pressure is a bit low.
First, analyze the factors that affect the rotational speed: 1. Steam flow rate, temperature, and pressure – this relates to quick-shut valves and throttle valves; check whether there is scaling, blockage, or sticking. 2. Vacuum level – pay attention to the exhaust temperature at the final stage. 3. If nothing else seems to be wrong, then check your moving components to see if the blades are damaged or if there is scaling on them
It is recommended to adjust the pressure to a slightly higher level first before discussing specific issues.
In my opinion, what is most doubtful is whether the oil actuator is indeed in place; impurities in the oil circuit can affect the actual opening degree of the oil actuator, thereby restricting the actual opening of the main steam valve.
Thank you all. The problem has been identified: there is a drain pipe connected in series with the water pipe in the main pipeline, which is causing internal leakage in the steam trap. As a result, water leakage into the steam pipeline caused the steam temperature to drop significantly. The steam enthalpy is insufficient. So the speed can’t go up.
The problem lies in the fact that the steam parameters are acceptable. :lol
Is there a leak in the check valve, causing water to enter the steam pipe? Is the condensate pressure higher than that of steam?