But Spring may also be the worst time of the year for the most sensitive people as they start to have increased allergic symptoms. Most of these symptoms are caused by the high concentration of pollen and road dust in the air. Typically, these symptoms are treated by sneezing a lot, wearing a face mask, maybe even taking some allergy medication.

Pollen is causing symptoms also in your gas turbine plant. The inlet air system acts as your nose and your only option for a 'facemask' is the inlet air filtration. There is no medication for the gas turbine symptoms and your filters cannot sneeze. To be fair, pulse type filters can actually 'sneeze' too, but pulsing is not available for pre-filters affected mostly by the pollen problem and pollen is problematic even for pulse filters as the pulse just blows the pollen over to other nearby filters.

What effect does Pollen season have on your plant?

The increased particle loading of the filters due to spring time pollen is showing up on your filtration system´s dp graph. Higher dp means higher output loss. The rate of dp growth also increases as the filters become more blocked. Combining the high organic content captured in your filters with increased air humidity from melting snow may cause your filters’ dp spikes to reach alarm and even trip limits much quicker than you would expect.

Why is pollen so difficult for filters to deal with?

Pollen particle sizes can vary between 10 to 1000 microns, so they are easy to capture with standard filtration. Due to the large particle size, the loading is distributed almost evenly between prefilter and fine filter stages. A proper prefilter is capturing more than 50% of pollen particles while an F9 fine filter captures more than 98% of the remaining pollen particles. Without E11 HEPA filtration though, your compressor blades are getting a pollen coating and you still need to do some washing to recover the power loss caused by the 'Spring miracle'.

It is easy to understand why filters get blocked when the pollen cloud with thousands of pollen particles per cubic meter hits your inlet air filtration system. For reference you can have a look at your car standing outside on the worst pollen days - your gas turbine is sucking in hundreds of cubic meters of the same pollen rich air - every second.

Adding to the spring misery there are also days of high street dust concentration when the streets near by your plant are being cleaned after the long winter, and the air quality analysers are reading PM10 daily average values several times higher than normal with the worst days being higher than 100 µg/m3 concentration regarded as unhealty for sensitive humans.

How to cope with the pollen problem?

With high pollen concentration and high air flow the only way of coping with the pollen problem is to have a sufficient filtration surface area left in your filters – or at least having a spare pre-filter set in stock for a quick change out if your alarm window is constantly blinking the high dp warning.

Spring comes every year and pollen with it. It´s just the question of how severe the pollen count will be from year to year.

If you are experiencing filtration problems this spring, you may want to contact your Friendly Filter Guy Pertti Sundberg - and we will come up with a better filtration solution to your problem!