Modern process designs for very high NGL recovery
Typical margins between NGL and sales gas can justify consideration of very high NGL recovery from natural gas but traditionally, very high percentage recovery of propane or ethane has led to disproportionally high incremental power consumption and hence expensive compressors. Recent technical advances in the process design of cryogenic gas processing plants and in the equipment they se have led to a new breed of flowsheets that can cost-effectively give propane recoveries of as high as 99%. The high NGL recovery achievable with modern plants is economically possible due to their high thermodynamic efficiency. This is mainly because they use the refrigeration available from the process more effectively and so recover more NGL. A high pressure rectification step can further improve NGL recovery economically, especially on larger plants. This residual NGL content would normally remain in the sales gas on a conventional turboexpander plant. Improved recovery of NGL can be obtained with little or no increase in sales gas compression power compared to conventional plants by judicious use of heat exchanger area. With high feed gas pressure and particularly with dense phase operation, the use of two expanders in series for feed gas let-down gives good process efficiency and relatively low specific power per ton of NGL recovered. Use of two expanders also avoids excessive liquid flows in the expander exhaust, thus improving the performance and reliability of the turboexpander system. The techniques discussed in the paper can be employed on revamps to improve NGL recovery. Improved process performance relies heavily on the use of efficient, multistream plant-fin exchangers and these can be easily added to an existing facility to increase NGL production.
- Research Organization:
- Costain Oil, Gas and Process Ltd. Manchester (GB)
- OSTI ID:
- 20000920
- Report Number(s):
- CONF-990331-
- Resource Relation:
- Conference: Gas Processors Association Seventy-Eighth Annual Convention, Nashville, TN (US), 03/01/1999--03/03/1999; Other Information: PBD: 1999; Related Information: In: Gas Processors Association seventy-eighth annual convention, proceedings, 393 pages.
- Country of Publication:
- United States
- Language:
- English
Similar Records
Upgrading straight refrigeration plants for NGL enhancement
$120-million module type NGL plant moved by LASH to offshore Indonesia