International comparison CCQM-K77: Refinery gas

Abstract

Refinery gas is a complex mixture of hydrocarbons and non-combustible gases (e.g., carbon monoxide, carbon dioxide, nitrogen, helium). It is obtained as part of the refining and conversion of crude oil. This key comparison aims to evaluate the measurement capabilities for these types of mixtures. The results of the key comparison indicate that the analysis of a refinery-type gas mixture is for some laboratories a challenge. Overall, four laboratories (VSL, NIM, NPL and VNIIM) have satisfactory results. The results of some participants highlight some non-trivial issues, such as appropriate separation between saturated and unsaturated hydrocarbons, and issues with the measurement of nitrogen, hydrogen and helium.Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Advances in metrology for energy-containing gases and emerging demands

“…In these key comparisons, the uncertainty evaluation included also a contribution for sampling effects. The same approach has been used in CCQM-K77 [10] (refinery gas). In an effort to reduce the costs of preparing the transfer standards, in CCQM-K112 and CCQM-K118 these were obtained from a speciality gas manufacturer.…”

“…Further CCQM-GAWG key comparisons addressed mercaptans in methane (CCQM-K65 [90], see section 8.2), composition of refinery gas (CCQM-K77 [10], see section 7.1) and liquefied petroleum gas (LPG, CCQM-K119 [11]).…”

“…There were 8 participants. The amountof-substance fractions of the components to be measured included those of methane (11%), ethene (14%), ethane (2%), propene (4%), propane (0.5%), 1,3-butadiene (1%), 1-butene (0.5%), iso-butene (0.5%), hydrogen (7.6%), nitrogen (4%) in a balance of helium [10]. The mixtures were prepared gravimetrically and verified before shipment to and after return from the participants.…”

“…In its pure form, this component has a tendency to form a great diversity of dimers [95] and subsequently polymers. The purity analysis of the 1,3-butadiene used for preparing the transfer standards for CCQM-K77 [10] reveals the presence of one of the dimers as a principal impurity (figure 6). Overall, four laboratories had satisfactory results for all components.…”

“…Examples of the latter include biogas, biomethane and liquefied biogas (LBG)' [9]. In the CCQM-GAWG programme of key comparisons, this trend has been reflected by key comparisons on refinery gas composition [10], biogas composition and composition of liquefied petroleum gas (LPG) [11] , which were organised after a programme of key comparisons dedicated to natural gas composition only [1,[12][13][14][15]. Also the gravimetric gas mixture preparation using liquid injection has been subject of a key comparison [16].…”