Compact inline separation equipment
The CDS StatoilHydro Degasser separates gas from a continuous liquid stream. Its compact inline design saves considerable weight and space. It is therefore particularly attractive for new topside and subsea systems, and for debottlenecking and upgrading existing production facilities.
How it works
In the degasser the liquid-dominated stream
flows through a low-pressure drop mixing element. This evenly distributes the gas bubbles present in the liquid phase. A stationary swirl element brings the stream to rotation, causing the gas to migrate to the centre of the cyclone while the liquid forms a spinning film on the inner wall of the cyclone. The gas leaves the cyclone via a pipe in the centre of the cyclone. Further downstream an anti-swirl element stops the rotation of the liquid stream.
Sample application
On the StatoilHydro Statfjord B platform, produced
water is expanded from 60 to 6 bar (870 to 87 psi) across a control valve. The gas released by this pressure drop gas created a slug flow regime in the downstream line, causing severe vibrations in the piping and unstable flare control. This was a problem from both a safety and an environmental point of view.
Lack of deck space made the installation of a conventional separator impractical. Instead, a compact CDS StatoilHydro Inline Separator was used. Prior to installation, a full-scale 18" degasser was extensively tested at an onshore facility. The degasser has now been in continuous operation since installation on the platform in September 2003. It has been performing extremely well, with a stable flare system and no more vibration as a result. The gas separated from the water is very dry and can easily be recompressed, reducing the amount of gas flared to the atmosphere, which in Norway generates significant savings in environmental tax.
Features/Benefits
Benefits
- High capacity, high separation efficiency
- Wide gas and liquid flow range and high turndown ratio
- Low pressure drop
- Upgrades existing separation plants and optimises their performance
- A very open structure: not sensitive to fouling
- Can be manufactured from any material used in offshore applications
- If sand is expected, erosion can be prevented by applying a coating such as tungsten carbide
- Has a significantly shorter delivery time than a conventional separation vessel
- Proven state-of-the-art patented technology
Ease of installation
- Inline design, cyclonic separation: no vessel required, installed inline with piping
- Compact, lightweight, minimum space required
- Tailored design for any application, low installation costs, easily customised. Also suitable for subsea installation.
- Often pays for itself through increased production
- Easily and quickly installed - no vessel entry required
- Limited downtime and short turnarounds
- Minimum maintenance
Characteristics
- Separation efficiency: 90% to 99% gas from liquid removal
- Gas turndown range: 55% to 0%
- Liquid turndown range: 50%
- Gas load: up to 55% volumetric gas fraction
- Liquid load: unlimited
- Pressure drop: 0.5 to 2.5 bar
- Degasser diameter: unlimited
- Degasser length: 8 to 10 times diameter
- Degasser height: 4 to 6 times diameter