Injector Fouling Performance and Solubility of GTL Diesel Dosed with Zinc

SAE International Journal of Fuels and Lubricants April 2013 vol. 6 no. 1 276-288
Injector Fouling Performance and Solubility of GTL Diesel Dosed with Zinc
Adrian James Velaers, Stefan de Goede and Christopher Woolard
Sasol Fuels Technology
Ross Burnham
University of Cape Town
Abstract
Nearly all new diesel engines use common rail diesel injection technology. The technology is characterised by high fuel injection pressure and very small diameter nozzle holes. The industry developed a new test procedure to assess a fuel’s propensity to cause injector fouling, as well as to assess the ability of additives to clean the injectors. The CEC F-98-08 DW10 test procedure requires 1ppm zinc to be dosed into all test fuels in order to accelerate injector fouling. Authors report DW10 test results for gas-to-liquids (GTL) diesel.
Researchers developed a similar test method, using a different engine, showing good correlation with the DW10 test. The results confirm a significantly different response with GTL diesel compared to regular diesel when both have been dosed with zinc. A series of chemical laboratory test work investigated the solubility of zinc in GTL. The results show that, when compared to EN590 diesel, zinc more readily drops out of a GTL-zinc solution, prepared in a similar way to that used in the DW10 test. It was also found that zinc is less readily taken up into solution with GTL from solid zinc components than it is by EN590 diesel.
The lower solvency of GTL diesel results in greater injector deposit formation due to zinc drop-out in the DW10 test method. Zinc pick-up tests, however, show that GTL diesel is less likely to pick up zinc in the logistic chain in the market.
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