PEFTEC - Abstract

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Abstract Title: Natural Gas - The determination of physical properties according to EN ISO 6976: 2016 ‘Natural gas – Calculation of calorific values, density, relative density and Wobbe indices from composition’
Abstract Type: Oral
Session Choice: Standards & Quality Assurance
Presenter Name: Mr Roberto Parola
Co-authors:Dr Kevin Cleaver
Company/Organisation: The Linde Group
Country: United Kingdom

Abstract Information :

A very brief overview of the preparation and certification of synthetic natural gas reference standards is presented.

The international and intra-national custody transfer of natural gas usually requires the determination of the quantity and quality of the gas. The methods for the calculation of key physical properties derived from the composition of natural gas are presented and the key differences between the ISO 6976: 2005 standard and the newly published ISO 6976: 2016 detailed.

These properties, namely gross and net calorific value, density, relative density, and gross and net Wobbe index are used to characterise gas quality. The methods detailed in the 2016 standard provide a means of calculating these properties and the associated uncertainties for natural gas or similar combustible gaseous fuel of known composition at specified reference conditions.

The values calculated in accordance with the 2016 standard will generally differ, albeit by very small amounts, from those hitherto calculated using the 2005 edition of the standard. These changes and the impacts on the natural gas industry and the regulatory framework within which the industry operates are discussed.

This includes changes to pure component and auxiliary values, methods of calculation, additions and removals from the standard, including the calculation of uncertainties based on compliance with the GUM.

The adoption of this new standard will lead to small changes in energy determinations and hence recorded energy content. Whilst these changes are small they may be significant and not lost in the "business cycle". Likely changes in the regulatory framework, the equipment and associated systems and the potential financial impacts of these changes on the industry are also considered as is the need for an impact assessment in order to agree timing for implementation and likely issues arising.