To make diesel fuel with high performance and optimal hydrocarbon content, modern methods of component content measurement are required.
It seems impossible to achieve without using additives. Additive efficiency depends to a large extent on the hydrocarbon composition of diesel. Additives for diesel fuel are mostly selected by trial and error. This stage is one of the most problematic for fuel producers. The main difficulty is combining surfactants of different nature and the consideration of susceptibility of fuel to additive packages.
It often happens that one additive improves a property and worsens another. For instance, a cetane improvement additive degrades lubricity, increases fuel density and viscosity. A lubricity additive reduces the susceptibility of the fuel to cetane improvement additives. Therefore, combining of these two types of additives requires increased concentrations. Using dispersers and pour point depressors can have a synergetic effect.
The current research is focused on selection and development of both multifunctional and individual additives. While the research is ongoing, there is a limitation: it is mostly performed on a specific type of diesel fuel. The composition of the product may vary even at one refinery. It is impossible to say that a fuel with good susceptibility to additives made by a certain manufacturer will be similarly susceptible to additives by another manufacturer. The problem can be solved by quickly adjusting the concentration of the additives or selecting more efficient additive concentrations.
The depressor and dispersion additives are the most sensitive to the hydrocarbon content variations of the fuel. An insignificant change of the n-alkane and amount and their molecular weight distribution reduces the low temperature properties of diesel fuel. Even stratification may occur in case of cold storage.
To sum it all up, knowing the hydrocarbon content of diesel fuel is a prerequisite to the production of high quality fuel and a basic tool for making the correct decision if the content of the fuel changes.