distillation (fractional distillation)

Distillation separates a liquid mixture into components by exploiting their different boiling points: the mixture is heated, lighter compounds vaporise first, and the vapours are condensed back into liquid at different temperatures to give separate fractions. It is the same principle used in petroleum refineries to split crude oil into LPG, naphtha, kerosene, diesel and heavy residue, applied here at a much smaller scale to upgrade pyrolysis output.

Raw pyrolysis oil from a tyre or plastic plant is a dark, mixed crude containing light volatiles, a diesel-range middle fraction, heavy waxy residue, water and suspended carbon. Sold as-is it is a low-grade furnace oil substitute fetching a modest price, and its high residue and moisture make it unsuitable for engines or for fuel buyers with tight specifications. Distillation addresses this: a typical small unit removes the water and light ends, draws off a clean diesel-like middle distillate, and leaves behind the heavy bottoms. The middle distillate is clearer, lower in sulphur and residue, and commands a meaningfully higher price than the crude pyrolysis oil it came from.

The economics turn on the price uplift versus the added cost. A distillation column adds capital (a heated still, a fractionating section, condensers, a vacuum or atmospheric setup) and operating cost (energy, labour, residue handling), and it does not increase the volume sold — in fact the heavy bottoms become a lower-value or disposal stream. It pays off only when the price premium on the cleaner distillate, multiplied by the yield that ends up as saleable distillate (often 60-80% of the input), exceeds those added costs. Where local buyers will pay a real premium for clean fuel, distillation is worthwhile; where the only buyer wants cheap furnace oil regardless of grade, it may not be.

For an Indian pyrolysis operator the guidance is to decide the distillation question against your actual offtake, not in the abstract. Test your crude pyrolysis oil and your candidate distillate at a NABL lab, confirm a buyer who will pay the premium for the cleaner fraction, and only then size the still. Be conservative on residue: the heavy bottoms must have a home (re-blended into furnace oil, burned for process heat, or disposed of properly) or they erode the gain. Adding distillation without a premium buyer lined up is a common way to spend capital that the market will not repay.