Demisters

Demisters separate up to 100% of 2-5µm droplets in a gas flow.

A demister consists of multiple layers of mesh fabric knitted from metal or plastic monofilaments, crimped and then assembled so that the crimps cross in successive layers forming a pad.

The space between the wires is very evenly distributed throughout the demister and the surface area is extremely high per volume unit. The large volume of space in a demister means that the pressure drop is relatively low.

LC Hansa Engineering AB
Linda Caporicci Column internals, Droplet separation, Spray nozzles & systems, Other products
I look forward to providing product advice and solutions! Let's meet via a video call or a site visit. You can also phone or email us, of course.
AB Hansa Engineering AB
Alexander Bergman Droplet separation, Column internals, Spray nozzles & systems, Tank cleaning
I look forward to providing product advice and solutions! Let's meet via a video call or a site visit. You can also phone or email us, of course.
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Separation efficiency 100% for droplets >5µm

 

Demister design

A demister is a droplet separator made of a mesh knitted from metal or plastic wires. The mesh is assembled in several layers and forms a demister pad, which is always oversized in width to avoid the gas bypassing the demister pad along the vessel wall.

Demister design, function and efficiency is determined by wire diameter, number of wires, number of mesh layers, mesh size and overall demister height.

The space between the wires is very evenly distributed throughout the demister and the surface area is extremely high per unit volume.

A smaller demister is manufactured as a unit with a support grid on each side of the demister pad. A larger demister consists of several sections to allow for insertion and removal through the manhole during installation and maintenance.

The mesh in each section is larger than the support grid to ensure a tight installation between the different segments and the vessel wall.

 

Separation efficiency

As the process gas passes through the demister, the liquid is trapped in the space between the wires, the droplets grow in size and are drained by the force of gravity.

The large volume of space in a demister means that the pressure drop is relatively low. Separation efficiency is 100% for droplets >5µm, provided that the demister design is based on correct process and operating data.

The illustration shows the separation refficienct for droplets >5µm at a given gas flow rate in % of the calculated maximum allowable gas flow velocity.

Choice of material

Choice of material depends on temperature and composition of the gas stream, among other things. Demisters are made in a variety of materials in different types of plastic or metal, such as

  • 304L, 316L
  • Polypropylene, PP
  • Other special materials on request

Checklist important parameters

In order to offer an effective and sustainable solution, below are a number of process parameters that are important to consider when selecting and designing a droplet separator.

Sometimes it is difficult or even impossible to obtain information and data regarding the specific process. Together with our suppliers, we have extensive experience and we can make sound assumptions as a basis for designing the best solution for the process.

Operating data
GasUnit
Maximum gas volume flowm³/h
Gas density (operating conditions)kg/m³
Kinematic gas viscositymm²/s (cSt)
Operating pressurebar (a)
Operating temperature°C
Operating data
LiquidUnit
Liquid contentkg/h
Liquid densitykg/m³
Surface tensionnM/m
Dynamic viscosity of the liquidmPass
Geometrical data
DataInfo/unit
Flow directionhorizontal or vertical
Installed in columncolumn or pipe
Column diameter or dimensionmm
Opening for installationmanhole or vessel flange
Requirements
DataInfo/unit
Type of mist eliminatorwire mesh or vane type
Type of materialPlease specify
Separation efficiency%
Separation efficiency/Limit drop sizeµm
Maximum pressure dropmbar
Other requirementsPlease specify

Choose the right product for effective and optimised droplet separation

Every process is unique. The Knowledge base provides information on how droplet separation works and what questions need to be answered to achieve an effective and sustainable solution.

Founded in 1976, RVT Process Equipment is a leading supplier and manufacturer of droplet separators, packings, column internals and other products for mass and heat transfer processes.

RVT Process Equipment offers advanced engineering and technical support and has extensive experience in various processes and applications in the chemical and petrochemical industry, refineries, power plants, and pulp and paper. The R&D department houses fully equipped test units, available to carry out customer-specific tests when needed.

RVT Process Equipment has subsidiaries and manufacturing facilities in Knoxville, USA and in Kunchan, China.

 

Begg Cousland Envirotec has vast know-how and experience in the field of droplet separation with a complete range of demisters, coalescers and candle filters.

Many applications may be similar at a first glance, but there are often small differences that are crucial to consider for an optimal solution. With an extensive experience in many industries, Begg Cousland's technical team are able to deliver the most effective solution for a specific problem and process.