A Low Emission Diesel Fuel: Hydrocracking Production, Characterization and Engine Evaluations 932731

The new regulations for emissions in USA (California and other States), introduce a new quality requirement for diesel formulations. As an answer to these problems Intevep, S. A., has developed a hydrocracking processing technology, a very flexible process able to operate up to 100 % of cracked material and with a mixture of light to heavy gas oil in any proportion, and which operates at moderate pressure. The proper balance between hydrogenation and mildhydrocracking is obtained through controlling the temperature and by tayloring the catalyst composition. Production of diesel fuel with less than 10 % wt aromatics was targeted, in a scenario of minimum hydrogen availability. Very low sulfur levels are achieved and the aromatic fraction is composed mostly of mono-aromatic compounds. Tests were conducted using a commercial Isuzu diesel engine, installed on an engine test bench and operated on a 7-mode cycle. Data was taken on each mode and statistical procedures for averaging, weighting and analysis were applied to study engine operation.

Satisfactory combustion performance relative to high aromatic content fuels, was observed, based on a heat release analysis, comparing burning rates and fuel fractions burned on premix and diffusion modes. A reduced specific fuel consumption was determined to be due to high energy content. A screening version of the California Air Resources Board certification procedure for alternative diesel fuel formulations was carried out on a Detroit Diesel Series 60 engine, following successive hot start transient evaluations. Exhaust emissions of HC, CO, NOx, Particulates, SOF and Sulfates were determined. Results indicate the potential of this fuel formulation to reach the qualification of low emission diesel fuel. Chemical analysis and detailed fuel characterization are used to explain the low emission results and the effects of fuel composition on emissions. Comparisons with exhaust emission predictions for this particular engine indicate areas for further improvements.