What is the reason why the cooling circulation pump for the turbine condenser does not supply water?
Thread Content
After performing maintenance on turbine No. 1 circulation pump, we started the pump using negative pressure for water pumping; the outlet pressure was normal. However, after about 30 seconds, the outlet pressure dropped from 0.4 MPa to 0. The pump can no longer draw water; I’ve checked many places but couldn’t find the cause. Please advise.
Owner: What does it mean to start the circulation pump using negative pressure for water pumping?
Using negative pressure to draw water to start the pump does not result in a continuous flow of water; was it emptied? Is there a bottom valve? Has it been checked?
The pump has just been serviced, so it should be fine now. Then check whether the valve core of the pump’s inlet valve has fallen off; it may seem as though the inlet valve of the pump is open, but in reality the valve core has not opened ； Next, check whether there is air leakage at the inlet flange gasket of the pump, as well as at the flange gaskets and packing of the valves ； It is also necessary to check whether the pump’s seal is leaking air ； Let’s check it first.
Air leakage is a common issue; start with simple checks first.
Thank you all for your help; the root cause was still related to the sealing. It is now running normally.
Could the original poster please explain in detail? Is the seal failed or what’s wrong?
During maintenance, not all of the sealing packing was replaced; some of the packing had hardened and lost its elasticity.
Generally, the inlet is equipped with a water seal valve; it’s necessary to check whether sealing water has been supplied, as well as whether the exhaust valve on the balance pipe is open. Also, it’s possible that the pump was started too late – it should be started before a vacuum is established
To ensure the proper operation of the circulation pump, the circulation pumps used for cooling the turbines in power plants are generally installed in a semi-underground manner, so that the inlet of the pump is at a positive pressure head, thereby preventing air leakage from the pump’s seals and avoiding a shutdown of the entire power plant.