Natural Gas Reference Calorimetry
NPL holds the UK's natural gas reference calorimetry facility.
The calorific value of a natural gas mixture is calculated from accurate knowledge of two factors, the composition of the gas and the calorific value of each of the constituent components. The calculated calorific value of natural gas is used to determine the trading value of the commodity at all stages of the gas transportation business, including billing for the household end-user. Accurate and precise determination of the calorific value of each of the constituent hydrocarbon gases is therefore essential.
NPL holds the UK's natural gas reference calorimetry facility – an instrument initially developed at the Office of Gas and Electricity Markets (OFGEM)[1].
The calorimeter completely combusts a (gravimetrically-determined) known quantity of hydrocarbon gas and the energy generated from this is used to heat a liquid. The temperature rise of this liquid is measured and, after correction for a number of factors (such as external sources of energy), is used to calculate the quantity of energy liberated by the gas-burning reaction.
Work carried out with the calorimeter at OFGEM determined the calorific value of methane to be 890.61 ± 0.21 kJ.mol-1, consistent with the current internationally accepted value of 890.63 kJ.mol-1 [2]. There is, however, an outstanding need to determine accurate calorific values of other hydrocarbons - NPL's reference calorimeter can be made available for this purpose.
For further information on NPL's Reference Calorimeter, or any other of NPL's Natural Gas Services, please complete the form, or contact us using the following:
Customer enquiry line: +44 (0)20 8943 6372
Customer fax: +44 (0)20 8614 0569
E-mail: gases@npl.co.uk
References
[1] A. Dale, C. Lythall, J. Aucott and C. Sayer, Thermochimica Acta, 382 (2002), 47.
[2] International Standard ISO 6976