Hi all members !
I am young mechanical engineer. I have just worked in Power plant for 2 years so I have a little experience in this field. My plant have two Francis Turbines and two Turbine Inlet Butterfly Valves (TIBV). Nearly, my TIBVs are broken down and the main reason is the TIBV that cannot fall down (by counter weight) when it close. All TIBVs are the same error. I don't known why they are. It takes a lot of time for researching but I haven't discovered yet the best solution. So, I need helps from forum who can explain to me the way to repair may TIBV. Thanks a lot.

The Francis turbine is a reaction turbine, which means that the working fluid changes pressure as it moves through the turbine, giving up its energy. A casement is needed to contain the water flow. The turbine is located between the high pressure water source and the low pressure water exit, usually at the base of a dam.

The inlet is spiral shaped. Guide vanes direct the water tangentially to the turbine wheel, known as a runner. This radial flow acts on the runner's vanes, causing the runner to spin. The guide vanes (or wicket gate) may be adjustable to allow efficient turbine operation for a range of water flow conditions.

As the water moves through the runner its spinning radius decreases, further acting on the runner. For an analogy, imagine swinging a ball on a string around in a circle; if the string is pulled short, the ball spins faster due to the conservation of angular momentum. This property, in addition to the water's pressure, helps Francis and other inward-flow turbines harness water energy efficiently.

Regarding your issue with the TIBV's there are a few items you can inspect. Since the valve is controlled by counterweight it is imperative that the proper weights are set and positioned correctly. Second, make sure the valve does not bind and moves freely. Ensure the packing is adjusted per the OEM and apply the recommended grease. Overttightening packing can sometimes effect the smoothness and the seal the valve mates to the body. I take it the logic to control the TIBV is accurate if your TIBV oil to operate, ensure the proper pressure is set. Lastly, if all else fails there might be an issue with the way the valve seats. Take the valve body apart from the actuator and visually inspect the set for any damage. good luck and feel to post any additional questions you may have.

Thanks for your advices! But we have done as all that you said before, and the result is TIBVs not working. I'm trying to find the main reason that make the TIBVs not its close.

Now, I have a document (drawing enclose). Can you look through and examine? After that please tell me the main faults.

Thanks a lot.

Enclose:
servo.jpg

Assembly.jpg

Hydraulic diagram.jpg

If you remove the turnbuckle, can the valve move freely?
Does the arm stroke freely?
Are you limit switches set?
try to break down the system and isolate what is binding or which component has failed.
What troubleshooting have you performed thus far and what were the results?

Also your P&ID indicates hydraulic oil pressure,. make sure the oil pressure is accurate to operate the arm. ARe the servos working properly? is it calibrated properly such that the command matches the feedback and its physical stroke? thanks
Good luck