Production • Processing • Handling
Ensuring bunker fuels comply with legislation
Debbie Batt shows how sulphur and nitrogen content in bunker fuel can be regularly monitored to ensure compliance with new legislative requirements.
Debbie Batt muestra cómo el contenido de azufre y nitrógeno en el combustible búnker se puede monitorizar de forma regular para garantizar el cumplimiento con los nuevos requisitos legales.
Debbie Batt zeigt auf, wie Schwefel- und Stickstoffgehalte in Marinedieselöl regelmäßig überwacht werden können, um die Einhaltung der neuen gesetzlichen Anforderungen sicherzustellen.
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Fig. 1. Example of the sulphur calibration line used.
unker fuel, also known as heavy oil, number 6 oil, residual fuel (resid) or Bunker C is a low value product typically used aboard ships. Bunker fuel
comes from the refining process and is the liquid residue from crude oil fractionation after the the lighter fractions have been removed by distillation. Te residue is comprised of large molecules such as asphaltenes, waxes and contaminants from the crude that become concentrated in the residue. After removal of the heavy insoluble materials, the remaining liquid may be cut back with lighter fractions, (often high value kerosine or diesel fractions) in order to meet relevant specifications such as sulphur and viscosity. Te solids removed from the residue commonly go to road and roof tar. Tighter specifications on air quality
have largely ignored the bunker fuel market because of the difficulty legislating for oil products used at sea. In October 2008, the Marine Environment Protection Committee of the International Marine Organisation (IMO) adopted the revised Annex VI, Prevention of Air Pollution from Ships to the MARPOL 73/78 Convention, which sets limits on nitrogen oxide and sulphur dioxide emissions from ship exhausts, with consequent control
of bunker fuel sulphur content being imposed. Annex VI does not specify standard test methods to be used, but the test method of preference for sulphur is currently ISO 8754:2003, ‘Petroleum Products – Determination of Sulphur Content – Energy Dispersive X-ray Fluorescence Spectrometry’, which is stipulated in marine fuel specification ISO 8217.
Te IMO action applies to vessels in emission control areas (ECAs), which are currently in the Baltic and North Seas with proposals for North America and Canada. California has its own state- wide fuel restrictions in place that will operate until the North America ECA comes into force. In the ECA areas, ships must either switch to using a fuel with a sulphur level of <1.5 per cent or fit an exhaust scrubber system that will achieve equivalent reductions. Under the IMO agreement, MARPOL Annex VI (2008), the maximum sulphur level in fuel will be progressively lowered for an ECA to 1.00 per cent m/m on or after 1 July 2010 and 0.10 per cent m/m on or after 1 January 2015. In addition to the sulphur dioxide
reductions, new engines operating in these areas must use emission controls that also achieve an 80 per cent reduction in nitrogen oxide (NOx) emissions, starting from 2016. Te majority of NOx emissions are as a result of atmospheric nitrogen being exposed to the high temperatures and oxidative environment within the engine during the combustion process itself. However, fuel borne nitrogen contributes to NOx emissions and nitrogen-containing species in the form of contaminants or additives can be key markers of potential fuel quality issues. Te measurement of sulphur and nitrogen in bunker fuel is therefore becoming increasingly important as legislative limits decrease.
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