Production of oils involves many processes. Among those, selective purification of oil fractions is one of the most important. The process is based on extraction and removes tar, polycyclic aromatic hydrocarbons and other undesirable substances by solvents.
Selective purification improves viscosity and temperature properties of the product, its color, lowers coking ability. Phenol is the most used solvent, with furfuraldehyde coming second. Phenol is quite toxic, and research into safer solvents is ongoing.
After the process of selective purification, the refined result is the product without many of the contaminants. The byproduct is the extract with concentrated extracted tar.
The technology process depends on the type of solvent, raw material type and quality, the required degree of purification and the requirements to the quality of the end product.
Special extraction columns are needed for selective purification. In the phenol process, the temperature in the bottom of the column is 45-80 ºС, and 70-100 ºС at the top. In this case the temperature gradient of extraction is 10-20 ºС. The same parameter in the furfuraldehyde process is 10-30 ºС.
Speaking of solvent consumption, the ratio of phenol to the raw material is is 1.5-3.5:1, with higher numbers for furfuraldehyde. Refined and extracted solutions are the result of the process.
There are no reliable formulas at this time to calculate the refined material yield. This is due to the extreme complexity of taking into account all factors influencing the process of selective purification. The best way is to research the performance of industrial unit in terms of refined material quantity.
Note that in many reference books the data on yield and parameters of distilled oil fractions is presented based on various oils. Average yield is 50-80% of the input.
The main drawbacks of selective purification is complexity of equipment and high consumption of expensive solvents. GlobeCore offers simple oil purification units, which can extract particulate matter, gas and water from the oil. The GlobeCore technologies are very gentle to the product and there are hardly any byproducts. Even the sorbents fuller’s earth used in the machines can be reactivated and reused.