Huff and Puff
Huff and Puff
(OP)
We use reverse-pulse air system for online cleaning of turbine air intake (Donaldson GDX) filters. The source of air is the axial compressor itself, and a slipstream of compressed (8barg) cooled air is passed through series of Norgren filters, 40/25/5um particle size, before introduced to the pulse air grid inside the filter housing.
Since the environment is very humid (Equatorial Guinea, Bioko Island), reaching 100% saturation during nights, compressed and cooled air contains approx. 3% liquid water going into the filters. Last night we did a small exercise and tested the system in two ways:
1. Installing a temporary KO pot upstream of the filters, on one of the six turbines. Water collected: 1.5 liters/hr
2. Measuring quantity of water drained from the filter system itself, on another turbine. Water collected: 1.0 liter/hr
It appears that some of the liquid water passes through the filter system and is being blown back on to the main air intake filters during cleaning (huff and puff) cycles.
We have decided to test this system due to the fact that some of the main air intake filters started experiencing high pressure drop, leading to lower power output from gas turbines. We are wondering how much of this DP buildup is due to environmental conditions, and how much due to blowing liquid water onto the filter elements. And also to see what could be the best solution for eliminating this water from the system, e.g:
1. Installing KO pots upstream of the filters, or
2. Installing coalescers instead. Any recommended vendors?
We need completely automated system so that no field operator attention is required.
I would like to hear your suggestions, especially from people with a hands-on experience in this subject.
Best regards,





RE: Huff and Puff
The only thing I've ever found that works, is to swap out the plugged filters with cleaned ones, clean the plugged ones and store for the next swap out.
There is no such thing as a "completely automated system", especially, when it comes to "Operations & Maintenance" in hostile environments.
RE: Huff and Puff
RE: Huff and Puff
What is the quality of air required for cleaning air filters by backblowing? I couldn't find any standard with respect to that. I don't believe it has to be 100% dry, but perhaps 100% saturated is not so good idea as well.
RE: Huff and Puff
RE: Huff and Puff
I'm not sure if I understand well. What makes you think that the pulse system will be effective if it's DP-based while being ineffective when it is timer-based?
Interestingly, I have found an OEM schematic diagram showing that the air quality should meet ISO8573.1, class 3/3/3:
Particle size in micron: max 5
Pressure dew point: max -20C
Oil content: max 1 mg/m3
Recommended dryer to meet ISO standard: desiccant or membrane
This dew point indicates Instrument Air quality requirements (-40C dew point at ambient pressure).
RE: Huff and Puff
Timer based cleaning work well for high solids loading in air. Of course, a long period between pulses could be equivalent to DP based, but it would not adjust to changing dirt load conditions.