Particle Filtration

Filter systems used for turbine applications can be broken down into three main categories:

• Inertial filters (impingement separation)
• Depth filters
• Surface filters
  
  

Reflection filters, sand filters, and droplet collectors primarily utilize inertial filtration by flow deflection, which is effective for particle sizes > 5 µm. These systems chiefly serve as prefilters for air with high particle concentrations. These filters should be used only under constant air-flow conditions.

Filtering separators such as depth and surface filtration systems enable separation of much smaller particles (to > 0,1 µm).

Depth filters are usually made of random-laid fabric with great porosity. They are used for concentrations < 2 mg/m³ .

At higher concentrations (> 2 bis 5 mg/m³), cleanable surface filters such as cartridge systems are used. With these systems, the surface of the filter medium is structured in such a manner that a minimum of particles penetrates below the filter-medium surface, and that a dust cake forms on the surface. The advantage of surface filters consists of the fact that – when a prescribed pressure difference is reached – the filters are cleaned by pulse impact, and that they can be regenerated.