Will have empty hydrogen generator having a 9FB for saving electric power by stopping lubrication pumps. it will be left for a long period of time (over 1 year). From the operational point of view is always a risk when emptying and filling the generator. what maintenance work be performed to commission after a year? Compensates for saving energy with the commissioning of the oil seals after a long period of time.

Someone has experience in this area. Thank you

 

elomoon,

The OEM has guidelines for "laying-up" (prolonged idling/storage) for their generators. Have you contacted the OEM for their recommendations?

Yes, you will save money by purging the generator of hydrogen (with CO2), and then purging the CO2 with clean, dry air and shutting down the seal oil pump motor. The internal generator space heaters will need to remain energized, to prevent condensation of moisture inside the generator casing.

Environmental conditions (ambient humidity; temperature swings over the expected lay-up period; etc.) should also be considered when making any decision.

I don't remember how large (kW) the AC seal oil pump motor is, but I would have the suspicion that maintaining some positive pressure of clean, dry air inside the generator casing during prolonged non-operation with the seal oil pump in operation would not be very expensive and would actually help to ensure the generator remains free of condensation and the ingress of damp air--which would mean the likelihood of any extensive remediation before returning the generator to service would be lower, meaning the over-all cost of lay-up (including the cost to return to service) would be lower. (The presumption is that the turbine control system would remain energized and someone is present at the plant to respond to alarms--like seal oil pressure problems; moisture in the generator casing; grounds; etc.)

Hydrogen-cooled generators get shipped long distances and even stored for months, or even years, before being put into service. On every installation I ever worked on the internal generator space heaters were temporarily energized until such time as the permanent power source for the heaters was available and could be switched to--this to ensure moisture didn't enter and condense inside the generator casing.

Again, you should consult the OEM for their recommendations and guidelines for long-term lay-up/non-operation. They are likely the best source of information and recommendations. And, remember--there will need to be some detailed testing of the generator internals (PI; rotor PI; etc.) before returning to service--especially if the seal oil pumps are not used to maintain a slight positive pressure inside the generator casing. These need to be factored into the total cost, not just the reduction of electrical power consumption by shutting off the seal oil pump.

 

Thank CSA:

The generator is a 450 H and lubrication pumps/seal have an output of 200 kW. Had recently CONTROL post in on the explosion of a generator to purge the H2, is the discussion between the risks generated by empty and cost savings.