Finding the Balance

Gas turbines burn fuel with enormous volumes of air to produce energy via a generator. Of course the air is simply pulled from the atmosphere and so needs to be cleaned to prevent damage to the turbine from atmospheric pollutants. So clearly, the need for effective gas turbine air filtration is very important, but protection is not the only consideration for a turbine operator.

Perfect air filtration would bring an ideal state to each of the following:

  • Pressure drop over the filters – the lower the pressure drop the higher the output from the turbine (or the lower the fuel consumed for the same output)
  • Filtration efficiency – the higher the efficiency the cleaner the air and therefore the lower the damage and wear that occurs on the critical turbine components like blades
  • Maximum burst pressure – to ensure the highest factor of safety, the filter should be tested to destruction, especially in dust loaded, high humidity conditions – this worst case scenario tells the operator what level of safety he has should things go wrong

Summing this together highlights the complexity of choosing the perfect air filters for gas turbine applications. For that reason, buying air filters should not be considered a “catalogue” purchase.

Understanding the balance that the turbine operator wants to place on each aspect, means that the air filter manufacturer needs to provide a consultative approach to filter selection. The best filter companies will ensure that they acquire data from the local environment, match this to their detailed knowledge of the long term performance of their filters and then use a computer modelling program to establish how long a certain filter combination will last.

And this should not be static. Over the life of the power station, the local environment is almost certain to change. Construction of housing, commercial buildings and roads are the classic changes which effect the levels of pollution in the air. These changes will have an effect on filtration performance and so a regular review of this (as well as a review of the objectives of the power station) is essential to ensuring optimum performance throughout the turbine’s life.