in our site we have 2 GE-6FA+e GTGs. but there is no provision for inlet air filters cleaning with air. Could someone explain why there is no any pulsation system?. On what conditions it will be decided not to provide pulsation for inlet air filters.
It's really very simple--it's a purchased option in most cases. If the buyer wants it, it is included in the purchase price.
In a very few cases, the type of airborne contaminants in the location where the unit(s) will be installed will not lend themselves to being easily removed from the filter elements by pulsing--so, it's not recommended. But, that's in a rare few cases.
Most filter manufacturers make "pre-filters" (sometimes called filter "socks" because they slip over the filter like a sock on a foot) which can be very effective at increasing the interval between filter changes. You should contact the various filter manufacturer's representatives in you area of the world and they will be very happy to visit your site and make recommendations for helping to increase the intervals between filter changes.