Demister FilterBOLL & KIRCH

Demister filters and cyclone separators for gases

Droplet separators such as a demister or a cyclone are used to separate liquid droplets from flowing gaseous media and are used in the filtration of gases.

Reliable gas filtration with demister and cyclone

Demister filters (droplet separators) serve for liquid-gas separation. The demister acts as a pre-separator when the liquefied gas is highly contaminated. Solids can only be separated to a certain extend in the liquid. 

The cyclone, like the demister, is used as pre-separator when the gas is expected to be highly contaminated by liquid and solid particles. The cyclone separates high solids content as well as high moisture content. The separation efficiency is based on centrifugal force, which carries the particles to the outer wall of the cyclone.

How do droplet separators work?

Mist eliminators, also known as demisters or mist separators, work by removing the liquid droplets from a gas stream.

How do demisters work?

In a demister, the main separation mechanism is the inertial effect. Efficient separation is achieved in mist eliminators by repeatedly diverting the gas flow in the demister. During droplet separation, the droplets flow through the wire mesh. Due to the moment of inertia, they collide with the wire surface and then collect at the nodes of the knitted wire mesh. The collected liquid droplets then fall down as larger droplets, where they are collected.

The demister’s design depends on operating conditions such as the volumetric flow rate, in addition to the type of particle, the medium being separated, and the separation performance.

How do cyclone work?

To separate even the smallest and lightest particles, a fast rotating gas flow is necessary. This is supplied by the special introduction of the gas into the cyclone. Once separated by centrifugal force, the particles run down the inner wall of the cyclone into a collection zone. Because of the separation principle, the separation efficiency of the cyclone depends on the operating conditions. Widely varying operating conditions lead to varying separation efficiencies. Due to the required high gas velocity, a relatively high pressure loss has to be accepted.

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Areas of application of mist eliminators

Mist eleminators are used in chemical and petrochemical plants, in the offshore sector, in cooling towers, in environmental engineering, in evaporative condensers, and in power plants; anywhere drops need to be reliably separated from flows of gas. Mist eliminators not only improve process safety and increase the efficiency of gas scrubbing, they also contribute significantly to protecting the environment.

BOLLFILTER mist eliminators 

  • Duplex: BFD-CY, BFD-CYD, BFD-CY DBB and BFD-CYD DBB
  • Simplex: BFB-CY and BFD-CYD