Today, the desired properties of diesel fuel is mostly dictated by environmental considerations. The European community pays a lot of attention to environmental issues, making its requirements to chemical composition of diesel fuel ever stricter.
Thus, beginning with January 2005, the Euro-4 regulations, limiting sulfur content in diesel fuel to 50 ppm, came into force. Four years later, Euro-5 regulations were introduced, with 10 ppm max sulfur content in diesel fuel. Polycyclic aromatic hydrocarbon content requirement was reduced to 2%. With time, the regulations will be increased to 95% distillation point of 340-350ºС and the cetane number to 54-58. Fuels compliant with this standard, are made in Sweden, the UK, Finland and Germany.
Sulfur compounds are more difficult to remove from diesel fuel than from benzene, since the former are less reactive. Their rate of decay is significantly lower in transformation from triophen to trimethyldibenzothiophene.
Hydrodewaxing is applied for production of diesel fuel with the required operational parameters. The feedstock for this process is straight-run diesel fractions, which boil out of low sulfur, high sulfur and sulfur crude oil at 180-330ºС, 240-360 ºС and 180-360ºС accordingly.
To ensure low sulfur content in fuel (15 ppm or so), a deep hard hydropurification is required, at 9-10 MPa and 315-400ºС. Hydrogen consumption is high, and volume velocity of petrochemicals along cobalt-molybdenum or aluminum-nickel-molybdenum catalysts is low.
The following are the output parameters of the process:
- weight yield – up to 97%;
- hydrocarbon gas – до 0,7%;
- benzene – до 1,5%;
- hydrogen sulfide – до 2,5%.
The drawback of the hydrotreatment is its low versatility. GlobeCore manufactures and supplied versatile UVR-450/6 systems, which can lighten not only diesel fuel, but also HFO, benzene, kerosene and gas condensate, regenerate transformer, turbine and industrial oil. The unit does not require constant operator attention, operating in either manual or automatic mode. Human interference is only needed for start, stop and sorbent replacement.
The UVR-450/6 is very energy efficient. When switching from one processed product to another, it is only required to drain the remaining product from the system, replace sorbent and filters. There are no additional complicated operations involved.