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Delivering an operational installation for upgrading natural gas for sale

Our consultants were engaged by PowerGen (E.ON) to provide a gas treatment plant, allowing the feed gas received from Point of Ayre to be diverted from Connah’s Quay Power Station to the national transmission system (NTS), in the event that the Power Station turned down or was not operating.

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PowerGen (E.ON)

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Advisory and Concept Development
Specialist Design
Technology Integration


200 MMSCFD gas processing plant

designed and built

Nitrogen content reduced from 11% to 5%

Wide turndown and ramp rate and tight product specifications

Costain carried out basic concept and front end engineering design of a new gas processing plant to reduce the nitrogen content in the feed gas to meet the Wobbe Index required for NTS.

Costain led the conceptual study, pre-FEED and FEED work, overcoming the design challenges by:  

  • Using a leading edge in-house cryogenic patent, consisting of a double-distillation system with a pre-separation column,  meaning the plant was capable of operating under a range of conditions and flows with less power and tolerance to CO2 content.
  • Designing an integrated control system to deliver a more effective and simple operation of the plant.
  • Designing molecular-sieve adsorbers; not only water but also sulphur was removed before the cryogenic section.
  • Carrying out a full study of the cold boxes in the basic engineering, ensuring the constructability of our solution.
  • Carrying out detailed evaluation of the size and configuration of the heat exchangers, columns, separators, and pipe work, enabling us to provide the most cost-effective overall solution.

Our leading edge design and cost effective solution meant we were selected as the EPC contractor, to carry out the detailed design, construction and commissioning of the gas treatment plant.

Through combining our innovative design with a clear understanding of the client’s requirement, we achieved a cost effective, simple-to-operate solution and efficient design.

We believe that our success in securing this project in a competitive environment was due to our development of a design which truly met the requirements of the client. Also, a single point of responsibility enabled us to closely integrate the design between the basic concept and the detailed design and build requirements. This was only possible through a close cooperation within the design team and with the client.

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