Gas quality and gas quality fluctuations in E.ON distribution networks – The impact on gas usage

Pictures/Bilder: E.ON

»1 E.ON network regions including downstream networks in Germany

Pictures/Bilder: E.ON

»2 Calorific value and Wobbe index at 50 representative entry points in
E.ON distribution networks within the limits of DVGW G260 (blue)
(Ref.: 25 °C/0°C)

»3 Typical plot of the Wobbe index with small fluctuations
∆Ws < 0.7 kWh/m³

»4 Typical plot of the Wobbe index with average fluctuations
0.7 kWh/m³ < ∆Ws < 1.0 kWh/m³

»5 Typical plot of the Wobbe index with wide fluctuations ∆Ws > 1.0 KWh/m³ and two different gases

»6 Typical plot of the Wobbe index with constant wide fluctuations ∆Ws >1.0 kWh/m³

»7 Local variation of the Wobbe index at the surveyed entry points to the
E.ON distribution network

»8 Typical frequency distribution of the Wobbe index in a region with wide fluctuations ∆Ws > 1 kWh/m³

»9 Results of measurements on three condensing boilers operated with natural gases and test gases with a Wobbe index between 12.0 kWh/m³ and 16.1 kWh/m³. Output increases with WS /WSG20 and the air ratio decreases with WSG20 / WS. CO emissions remain low in the group H natural gas region

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In an internal project prompted by the intense debate surrounding the permitted Wobbe band in Europe, E.ON has analysed the gas qualities of gases distributed in E.ON networks in recent years and has identified their impact on the operation of appliances. The project is designed to identify, document and make available existing solutions in areas which already have fluctuating gas qualities and to develop and implement necessary measures for the future. The initial findings of the project are reported below.

1 Introduction

When European standard EN16726 for group H natural gas was developed, agreement was reached on various limits and targets. However when it came to the most important parameter for the interchangeability of gases in use – the Wobbe band – it was not possible to reach a consensus despite comprehensive research in the GasQual project and intensive work by technical committees at both European and national level. From E.ON’s perspective as a major German gas network operator and gas trader with business across Europe, there is a keen interest among the gas industry, appliance...