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The patented 4G-FD® Demisting Cyclones offered by Zeta-pdm Ltd are an entirely new generation of straight-through axial flow cyclones, designed with a completely original geometry in both the swirl zone and the cyclone tube. In these devices, the gas enters and leaves the cyclone body without any significant change in direction.

These high performance demisting devices combine highly efficient droplet separation characteristics with important practical advantages, such as simplicity of installation and non-clogging (minimum maintenance) capabilities. Conveniently, the cyclones can also be assembled in any configuration in both horizontal and vertical separators. Typically, the separation performance for a particular droplet class is improved by approximately 20% when compared to that achieved in conventional axial flow cyclone designs, for the same pressure drop across the device.

Droplets carried by the gas flow enter the cyclone through the optimised swirl element, creating a strong rotational motion. Under the influence of centrifugal forces, the droplets move across the gas stream until they impinge on the aerodynamically shaped body of the cyclone where they are separated out.

The patented design solves known issues such as liquid “creep” and introduces new features such as pre-separation in the swirl-element, and optimal fluid dynamic spin-up due to the elimination of re-cycle flow in the centre of the cyclone. Furthermore, some secondary separation occurs in the drainage chamber, thereby eliminating liquid entrainment from the drainage chamber back into the cyclone.

In addition to their ability to separate very small droplets at a relatively high efficiency, 4G-FD® Demisting Cyclones extend the operational flexibility of separators by eliminating the impact of foaming on downstream equipment such as compressors. They can reduce the use of costly anti-foaming chemicals by 50-100%.

Advantages of the 4G-FD® Demisting Cyclone:

  • Offers a high gas / liquid separation efficiency at high operating pressures and with complex fluids
  • Handles high flow throughput
  • Handles high liquid loading
  • Requires a low pressure drop for relatively high droplet separation efficiency
  • Provides a high turndown ratio
  • Reduces or eliminates the production of foam, thereby reduces OPEX by reducing the need for anti-foaming chemicals
  • Robust construction
  • Offers a wide operational range
  • Reduces the vessel size on a new build project
  • Allows a greater fluid throughput for a set vessel size, on a revamp project
  • Non-clogging design makes it suitable for installations with medium/high solids loading
  • Easy to install in both new and existing separators
  • No moving parts, so no maintenance.

Applications of the 4G-FD® Demisting Cyclone:

  • Production Separators
  • Test Separators
  • Gas Scrubbers
  • Gas Knock-out Drums
  • Slug Catchers
  • Flash Drums
  • Process Vessels and Columns
  • Floating Production Units (FPUs).

Case Studies

Horizontal Separator Flow Assurance

The horizontal separator vessel is one of the most important parts of the separation train. CFD can be used to develop an improved understanding of the flow within this vessel and the way in which the flow interacts with the internals. The flow detail provided by CFD enables the position and spacing of the baffles to be optimised.

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