132.0 Paraffinic fuels for diesel engines
Paraffinic fuels consist almost fully of alkanes and are therefore free from aromatics and sulfur. In addition to straight-chain and branched alkanes, some fuels also contain cycloalkanes. Due to their chemical composition, the properties of paraffinic fuels differ from those of regular diesel fuel and are specified for Europe in standard prEN 15940. The main differences between paraffinic diesel fuels and conventional diesel fuels are the higher cetane number, the lower volumetric energy content and the lower density.
As with diesel fuel as per EN 590, fatty acid methyl ester (FAME as per EN 14214) can be added to paraffinic fuel with a portion of up to 7 vol. %.
To ensure that customers in the market are able to distinguish between the different fuels, a clear marking is strongly recommended when selling pure paraffinic fuel (100 %). As a pure fuel it is usually only used in fleet cars. As a blended component on the other hand, paraffinic fuel is already being used in the market today.
A distinction is usually made between two paraffinic fuel types on the basis of the manufacturing method:
Paraffinic diesel produced through hydrogenationThe core production step for manufacturing this fuel is hydrogenation, i.e. the chemical conversion of raw materials with hydrogen. This manufacturing process can be carried out both in a stand-alone system but also within a pre-existing refinery process (co-processing). The abbreviation HVO (hydrotreated vegetable oil) is often used synonymously with paraffinic fuels manufactured by means of hydrogenation. Today, however, animal fats and other raw materials are used to manufacture these fuels in addition to vegetable oil and the designation HDRD (hydrogenation derived renewable diesel) is therefore a more appropriate generic term for this fuel type.
Fischer-Tropsch fuels – (XtL)To manufacture fuel, a mixture of carbon monoxide and hydrogen, referred to as syngas, is first produced from the raw material. In the subsequent step, the eponymous Fischer-Tropsch process, the paraffinic fuel is created from the syngas by means of the creation of a chain structure. The designations normally used relate to the raw material used to produce the syngas: coal - Coal to Liquid (CtL), gas - Gas to Liquid (GtL), biomass - Biomass to Liquid (BtL).
Use of Paraffinic Fuels in Mercedes-Benz Car EnginesUse of pure paraffinic fuel (100 %) is not approved in Mercedes-Benz car engines. However, paraffinic fuels are already being used by mineral oil companies as a blended component for regular diesel fuel. Provided that the diesel fuel complies with the EN 590 standard in Europe, it can be used in Mercedes-Benz car engines in any amount without restriction in admixtures of fuels as per prEN 15940. Biogenic paraffinic fuels (e.g. HVO and BtL) have excellent oxidation stability compared to fatty acid methyl ester (FAME) and are therefore a good alternative as a blended component.
Use of Paraffinic Fuels in Mercedes-Benz Commercial Vehicle EnginesMercedes-Benz commercial vehicle engines with the Euro VI standard emissions level,OM934, OM936 and the first generation of the OM 470 and OM 471 model series have been approved for paraffinic fuels since February 2016. Since July 4, 2016, the latest generations of OM 470 and OM 471 engines have also been approved for fuels as per prEN 15940.