www.npl.co.uk

GAS2013

Lucy CulletonNational Physical Laboratory, Hampton Road, Teddington, Middlesex, TW11 0LW, UK

lucy.culleton@npl.co.uk

 

ISO/TC 158Analysis of gases

Results of an international comparison of the analysis of real ‘non-conventional’ gas samples

(1) EC Directive 2009/28/EC - Promotion of the use of energy from renewable sources(2) EC Mandate M/475 (2010) - Mandate to CEN for standards on biomethane transport and injection into natural gas pipelines

IntroductionDiminishing natural gas resources and the need to meet renewable energy targets (1) are leading to the diversification of the European gas supply through the introduction of non-conventional gases into gas networks. There currently are urgent requirements for traceable measurements of these non-conventional gases, one example of which is to support a specification being developed to enable biomethane to be utilised within European natural gas networks (2).

The EMRP ‘Characterisation of energy gases’ project has been working towards putting in place a metrological infrastructure to underpin the ‘interchangability’ of energy gases within gas networks. The new gases include biogas, coal mine methane, coal bed methane and hydrogen-enriched natural gas. The project has developed new methods and standards for the analysis of these gases, which this poster shows to be capable of measuring real samples of non-conventional gases.

SamplesSix different samples of real gas were collected from various locations across Europe. The variety of mixtures provided the labs with a range of measurement challenges.

Sampling methodsThe real gas samples were collected in a variety of sampling vessels, which included cylinders and FlexFoil and FlexFilm sample bags.

Analytical methodsIn the six labs that performed the measurements, the analytical techniques used included GC-FID, GC-MS, GC-SCD, GC-AED and OFCEAS. The labs developed their own measurement methods, the comparability of which are investigated within this study.

# Sample Obtained by Sampling location Sampling Date Analytes

1 Coal Mine Methane BAM Saarland, Germany Mar 2013 Composition

2 Coal Bed Methane BRML INM Romania Nov 2012 Composition

3 Biogas (raw) SP Gothenburg, Sweden Apr 2013 Composition & impurities

4 Biogas (processed) SP Gothenburg, Sweden Apr 2013 Composition & impurities

5 Biogas (processed) BAM Neudorf, Saarland, Germany Oct 2012 Composition & impurities

6 Biogas (processed) MKEH Zalaegerszeg, Hungary Jan 2013 Composition & impurities

ConclusionsThe participating labs successfully measured the composition and impurity content of a variety of samples of real non-conventional energy gases. Although good comparability was generally achieved, some compounds had a wider spread of values across labs than others, particularly for the compounds measured in the sample bags. Possible reasons for the lack of comparability within the study include:

• Non-uniformity in gas sample collection methods.• Adsorption of components to the internal surfaces of sample bags. • Non-routine analyses as a result of the complexity of samples.

The study has revealed the challenging nature of the analysis of some of these gases, and provided an insight into the capabilities of current analytical techniques used for composition and impurity quantification.

ResultsComposition measurementThe real samples were analysed for their composition, which involved quantification of the amount fractions of: • C1-C9 hydrocarbons• Oxygen• Nitrogen• Carbon dioxide• Hydrogen

The graphs to the right show a comparison of the results for a selection of compounds across the four types of mixture.

Impurity measurement

The following impurities were measured in samples of raw, partially processed and fully processed biogas:• Hydrogen sulphide• Siloxanes (L2, D3, L3, D4, L4,

D5, L5 and D6)

Participating Labs:

74.16%

1.25%

19.27%5.10%

0.20%0.01%0.001%

0.21%

Coal mine methane from Germany(mol/mol)

MethaneCarbon dioxideNitrogenOxygenEthanePropanei-Butane

62.15%

36.40%

0.49%

0.17%0.005%

0.08%0.70%

0.74%

Raw biogas from Sweeden(mol/mol)

MethaneCarbon dioxideNitrogenOxygenHydrogenSiloxanesHydrogen sulphide

86.73%

1.65%

6.49%

0.79%

2.67% 1.24%

0.15%0.19%

0.05%

0.03%2.46%

Coal bed methane from Romania (mol/mol)

MethaneCarbon dioxideNitrogenOxygenEthanePropanei-Butanen-Butanei-Pentane

97.72%

0.51%1.10%

0.40%0.27%

2.28%

Processed biogas from Hungary (mol/mol)

MethaneCarbon dioxideNitrogenOxygenHydrogen