The manufacturing of marine fuels is facing increasing challenges as the result of tightening environmental legislation relating to emissions from shipping. This will affect fuel quality, mostly by the increasing demand for low sulphur fuels. At the same time the increasing demand for middle distillates for transport application, leads refineries to increased conversion, which normally impacts the volume and quality of heavy fuel oil. Properties particularly affected are stability and the ignition and combustion qualities. Poor ignition and combustion may result in unreliable engine operation. For that reason, consideration is being given to the inclusion of some form of ignition/combustion control in the international marine fuels standard, ISO 8217, namely the Shell developed Calculated Carbon Aromaticity Index (CCAI) value, which has been widely applied already as indicator of ignition quality. Another IP method to measure ignition quality, namely the Estimated Cetane Number (ECN) measured by Fuel Ignition Analyzer (FIA) is currently being considered for next versions. When new techniques are accepted for specification purposes it is important that these tests measure fundamental properties and have been subjected to a robust review process, so that a sound scientific basis is available that demonstrates the relationship to fuel performance and mitigates the risk of product quality incidents. First results of the evaluation of the FIA ECN by Shell Global Solutions have been presented at the CIMAC 2007 congress. As results were not conclusive, research in this area was continued with the purpose of further improving our knowledge of fuel oil ignition quality and better understanding the possibilities and limitations of FIA ECN. This additional work will be reviewed in this paper. The profound understanding of the influence of fuel composition on the ignition quality has been one of the main elements of the programme. Fit for purpose fuel is a key ingredient to have a trouble-free operation on a vessel. For that reason, the FIA ECN of a variety of refinery residual components was compared and related to the effect on the ignition quality of the final fuel oil. It was found that not all blending components can be measured directly with the FIA due to viscosity constraints of the method and that some blending components may show nonlinear blending relations. Therefore, it is not straightforward to blend to a certain ECN specification and it will increase complexity and costs. The second element is the influence of FIA test parameters on the FIA ECN. The FIA ECN is measured at a standard temperature and pressure, which is required for comparison of fuel samples. However, engines run normally at different temperatures and pressures, therefore several fuel oil samples have been measured at the standard FIA conditions and with varying FIA test parameters in order to identify the influence of those parameters on the ECN. The relative ranking of the fuel oil samples is also reviewed. It was shown that the temperature can change the magnitude of the ECN differences between the fuels. This indicates that a single FIA ECN limit might not be a good indication of ignition quality for different engines that operate at changing conditions. Ultimately, the ECN should provide a result that could be used to predict reliable ignition and combustion performance in diesel engines with a high degree of confidence. Therefore, the ECN of several fuel oils are related to the ignition data from 2- and 4-stroke engines, namely the AVL Caterpillar 1Y540 and the Bolnes 3(1) DNL 170/600 research engines at Shell and the Wärtsilä 4RT-flex58TB research engine. The ranking of the ignition quality of the fuel oil samples in the three engines and the ECN will be compared in the paper.
Investigating the ignition properties of marine fuels by the Fuel Ignition Analyser and its comparison to marine engines
2010
11 Seiten, 18 Bilder, 1 Tabelle, 5 Quellen
Aufsatz (Konferenz)
Datenträger
Englisch
Ignition properties for marine fuels established on the fuel ignition analyzer FIA 100/2
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