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Content archived on 2022-12-27

USE OF CRYOGENIC TURBO-EXPANDER IN SEPARATION OF LIGHT FRACTIONS IN NATURAL GAS

Objective

To replace two chilled lean oil gasoline recovery units by one cryogenic expander unit. The expander supplies simultaneously the cold needed and part of the mechanical energy for the recompression of the sale gas. The estimated saving is 19061 TOE per year.
Problems were experienced with the gas compressor which was damaged whilst being tuned-up by the supplier's representatives. Damage was sustained to the rotor and the unit was returned to the supplier for repair. This delayed the project by several months. The installation has been fully operational since October 1987.
The turbo-expansion technology applies to the gaseous phase coming out of the expander feed separator . This phase comes out in two streams:
- some 10-15 per cent is condensed and cooled in the exchangers EC-403 by the sales gas coming out of the demethaniser. It is then refluxed upstream of the demethaniser.
- the remaining 85-90 per cent is directly expanded in the turbo-expander generating on the one hand the frigories necessary to operate the demethaniser and on the other hand a part of the mechanical energy for the compression of the sales gas.
In order to ensure flexibility in the amount of ethane to be recovered, this project includes a partial recycle which does not affect the recovery of propane.
The commercial gas is delivered at three different pressures, one for each grid:
- low pressure (35-40 bars) : Local industries
- medium pressure (46 bars) : Pau-Dax-Bayonne
- high pressure (57 bars) : Boussens-Auros-Lussagnet.
The total cost of the project is estimated at FF 138,080,000.
The first phase covers the planning and engineering stage and will last from 9/84 to 3/86 followed by the building stage due to last until April 1987 and the demonstration phase to follow until end May 87.

Call for proposal

Data not available

Coordinator

Elf Aquitaine Production
EU contribution
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Address
26 avenue des Lilas
64018 Pau
France

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Total cost
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