Gas quality – Consultation on widening UK Wobbe Index limitsFrom the IFRF Office
Contributed by Philip Sharman
Sheffield, Monday 27th November 2017
In the last edition of Monday Night Mail (13th November), two contributions were directly relevant to likely forthcoming changes of standards dictating what gases can be combusted in industrial, commercial and residential appliances. The first was the publication of an excellent paper on ‘The Changing Scene of Natural Gas and Alternative Fuels’ by Terry Williams of Orbital Gas Systems (click here to view), which describes natural gas quality variations worldwide and looks forward in time to predict further changes. The second was a ‘thoughtpiece’ on the COP23 Climate Change Conference in Bonn that mentioned, as a possible response to current climate challenges, the importance of switching from higher- to lower-carbon fuels (such as biomass, biogas, hydrogen, etc.). Both of these pieces explicitly or implicitly refer to gas quality, and the likely move (and need) to widen the limits of certain gas quality parameters – particularly the ‘Wobbe Index’ of gases for combustion.
On this specific subject, the Institution of Gas Engineers & Managers (IGEM) in the UK is currently working on the production of a new standard covering UK gas quality specification in order to facilitate a change from the Gas Safety (Management) Regulations 1996 (GS(M)R) that reflects the available alternative sources of gas and aligns with the European standard. This new standard will set the Wobbe Index range appropriate for the UK, initially examining the extension of the upper range. The specification will also seek the further widening in the lower range at an appropriate stage. Furthermore, this review will consider the impact of Emergency Specification, the interaction with the wider ENA GS(M)R review process and impact in Europe (CEN Standard and Security of Supply Regulations).
As part of this work being undertaken by IGEM, DNV GL have been tasked with looking at the impacts of gas quality on industrial and commercial users. The project will explore the effects of a wider gas Wobbe Index, including blended hydrogen mixtures (containing up to 20mol% hydrogen), by researching the measures in place around the world to ensure safe and efficient combustion of wider specification gas. The research will also include the effects of rate of change of Wobbe Index. The industrial and commercial equipment examined will be greater than 1 MW in size, and the research will also consider any instrumentation which measures, or may be affected by, gas quality.
The range of Wobbe Index for this study is 45.67 to 53.25MJ/m3 (compared with the existing GS(M)R range of 47.20 to 51.41MJ/m3). This range is not exclusive and information within and outside of this range will be considered.
A questionnaire has been created to assess the potential impact on UK industry of a wider range of gas quality. DNV GL will study the types of plant and control systems which currently exist in the UK and whether these would need to be adjusted or modified to accommodate wider gas Wobbe Index limits.
All organisations that form part of the ‘UK gas industry’ are invited to complete the questionnaire (please click here to access) and return it by email to firstname.lastname@example.org by the deadline of 15th December 2017.
IFRF warmly welcomes this initiative and looks forward to a much broader range of (low carbon content) gaseous fuels being utilised in the UK as a result.
Other articles from week 48:
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