· Conducting a high-level survey of the NTS to look at the prevalence of bi-directional flow both now and in the future. Evaluate the mixing arrangement options to determine if there are alternative approaches to reduce site size.
· Compliance with GS(M)R as well as maintaining the calorific value of the prevailing flow which is a commercial issue. Use the NGGD/NGN Flow Weighted Average Calorific Value NIA project to inform this work.
There is a strong link between this study and the NIA project NIA_NGGT0070 NTS Block Valve Connections. NIA_NGGT0070 focusses on an engineering design solution for block valve connections, and the information and new learning from this work, particularly on sampling and blending will help determine the most efficient design solution.
To provide answers to the following two key challenges to the current process:
1. Oxygen content: the GS(M)R limit for oxygen is 0.2 mol%. Unconventional gas supplies may have higher oxygen content, and whilst gas distribution networks have an exemption to allow biomethane sites to flow up to 1 mol% oxygen, no such exemption exists for the NTS. Is this appropriate?
2. Gas Quality Blending: the co-mingled gas quality sample point location is set at 20 pipe diameters from the injection point, in line with current ISO standards. Is this appropriate for smaller unconventional gas connections?