Partial removal of paraffin from diesel fuel by direct current fields is quite efficient. First, it allows to improve the low temperature performance of fuel. Second, diesel fuel retains some of the n-paraffin hydrocarbons, which define the cetane number. Third, removal of paraffin increases diesel fuel yield from crude oil in comparison to traditional purification methods. Fourth, the electric purification process is significantly simpler than such methods as hydrodewaxing. The drawback is the requirement of low temperature for the process, which, incidentally, also makes it suitable for cold areas.
Removal of paraffin requires special electric dewaxer machines. Each cycle of operation consists of several operations.
First, diesel fuel premixed with an additive enters the interelectrode space through lower side inlets of the system. The fuel can travel from one interelectrode space to another through gaps. Positively charged electrodes are meshes and do not impede movement of the liquid.
To eliminate overflow when fuel level is exceeded, the fuel is drained through the top connector to a special vessel. The interelectrode space is pre-calculated and must consider the thickness of sediment forming on the electrodes. In practice, the sediment rarely exceeds 10-15 millimeters.
When the electrodes are energized, paraffin sediment forms on both sides of the electrodes. Diesel fuel is then removed from the chamber, maintaining power on the electrodes.
The equipment is built with an incline to outlets to accelerate output of the processed fuel.
After fuel is removed, power is disengaged, then paraffin is removed from the electrodes. The latter operation is carried out by warm liquid. The molten paraffin drains to the bottom of the tank and is removed through lower outlets.
After this, the machine and the bottom of the unit should be cooled down to process temperature. To do so, cold liquid is circulated through the tank.
Kerosene, thickened with silicagel or calcium chloride, serves as both cooling and heating agent. Its dielectric properties are also a factor.