Generator Operation 1

[EETD]

I am applying a 600kW primary service diesel generator at a manufacturing factility with an 8 to 10 hour production shift. A small load (i.e. 30 to 60kW) would need to be maintained for the remainder of the day.

In general, when the facility is not in operation (16 hours a day) is it better to:

a) Let the generator run at 5 to 10% of its full capacity, or

b) switch off the main generator during that period and use a smaller generator to supply the nighttime load?

Thanks is advance for your thoughts.

Regards,

EETD

 

[rbulsara]

See thread238-69215 discussing the issues with light loading the generator.

I think option b) is better one.

 

[rbulsara]

Or buy utility service for nite time light loads, if not so critical..

 

[RRaghunath]

It is not good to keep the diesel engines on if the load falls below 30% of its rating. I understand this causes carbon formation in the cylinders and thus leads to increase in maintenance expenses.

You may find advice in the DG set O&M manual.

Hope it helps.

 

[jack01]

To run a generator at less than 50% load for extended peroids of time can cause a condition called 'wet stacking'
this is when the injected fuel is not being fully consumed in the combustion process. The excess fuel will migrate down back toward the engine, some will collect in the muffler and some will flush any collected carbon back into the cylinders. This can cause damace to the cylinder wall causing premature failure, fuel collected in the muffler could ignite and result in fire.

 

[alehman]

Wet stacking is typically a problem only for extended runs at low load (<30%). If the engine operates at higher load during the day, that should clean out any buildup that happens at night. I doubt that wet stacking would be a problem unless it runs for many days in a row with low load. I would suggest a different reason to invest in a smaller genset - fuel efficiency. A large engine running with very small load consumes more fuel than more more closely matched to the load.

 

[EETD]

Thanks everyone for your responses. They have been very helpful.

EETD