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The Properties and Injector Nozzle Fouling Performance of Neat GTL and GTL/EN590 Diesel Blends in Various Diesel Engines
Abstract:
The combination of high crude oil prices, energy security
concerns and environmental drivers have resulted in an increased
focus on alternative fuels. Gas to liquids (GTL) diesel is
considered to be a promising alternative diesel fuel, given that it
can be used directly as a diesel fuel or be blended with
petroleum-derived diesel or biodiesel. GTL diesel fuels are
predominantly paraffinic and possess several excellent inherent
properties including virtually zero sulfur, very low aromatics
(≺1%) and very high cetane values (typically ≻75).
Currently GTL diesel is mostly sold into the European market as
a blend stock for the extending and upgrading of petroleum-derived
diesel fuels. Given GTL diesel's inherent paraffinic nature,
the density of this product is below the European minimum 820 kg/m₃
EN590 specification (at 15°C). Typically up to 20% (vol) GTL diesel
can be blended into crude-oil-derived diesel in order to meet the
minimum European density specification, although neat applications
of GTL diesel have also received some attention in literature. This
study presents some findings pertaining to injector fouling for
neat and 20% (vol) GTL diesel blends on a variety of diesel
engines. There is however, very little information in the open
literature on the physical and injector fouling performance
properties of higher binary blends of petroleum-derived and GTL
diesel. Several markets do not have a minimum density specification
(e.g., the USA, Canada, Uzbekistan), while several countries have
winter density specifications lower than 820 kg/m₃, including
countries like China, potentially enabling GTL diesel to be used at
higher blending ratios and in its neat form.
In the current study, neat low temperature Fischer Tropsch
(LTFT) GTL diesel and EN590 diesel fuels, together with blends
containing 10, 20, 30, 50, and 80 volume percent GTL, were analyzed
for their physical and chemical properties. The injector fouling
performances of these blends were assessed in the CEC F-23-01 XUD9
and Sasol common rail tests. Many of the physical properties of
these blends were influenced positively by the addition of GTL
diesel to the EN590 fuel. Overall, it was concluded that at low
percentages, blends of GTL diesel with EN590 resulted in similar
injector fouling performance in the CEC F-23-01 XUD9 and Sasol
common rail tests. At higher GTL diesel contents, a significant
injector fouling performance improvement was found.