During last Hot gas patch inspection (HGPI)of unit#02 (GE7FA DLN 2.6), we have installed GE make nano filters in air inlet filter house. while other unit replaced with braden filters.

I just wonder what is the difference between nano filters & braden filters? do they are similar? GE claims that nano filters are with very high filtration efficiency.

We have replaced both type filters during October-09. and currently DP for GT#01 is 51 mmwc & GT#02 40 mmwc.

 

Did machines start at the identical differential pressure after the filters were replaced?

Were both machine's compressors clean after the outages?

Are both machines producing virtually the same compressor pressure ratios?

How is efficiency being defined by GE?

How are you defining efficiency?

To my mind, a filter which captures smaller particles will likely "get dirty" faster than a filter which doesn't capture such small particles.

However, any particles which do get through the filter will contribute to compressor fouling.

So, you might need to be looking at how frequently you've had to perform water washes (off-line and/or on-line) on the machine with the "higher efficiency" filters versus the other unit.

Also, look at the performance degradation over time of the two machines. I would suspect the performance degradation of the machine with the more efficient filters would be less than the other machine.

You should ask GE for information on the claims, how they define filter efficiency and how they arrived at their claims. I would think the sales person should gladly provide that information, and any sales person worth his salt would help you to quantify the effectiveness of the filters you've purchased to help you understand how much better these filters are than the competition's.

Please, let us know what you find out.