This morning I’m going to try and build up my knowledge of the fuel production process. The goal being to ELI5 the whole process.
The aim is to get some range of hydrocarbons of particular chain lengths from an initial substance that has hydrocarbons but not in the desired composition.
Hydrotreating: aims to remove impurities like sulphur and nitrogen.
Distillation is a separation technique. It takes advantage of the differing boiling points of molecules in a substance. The lighter the substance, the lower its boiling point (temperature at which it changes from liquid to gas). Heating a composite liquid will create vapour that will condense at lower temperatures the lighter the molecules.
In simple distillation you’ve a substance with sufficiently different boiling points. Heating the mixture to above the boiling point of one, turning it to vapor which should leave a large portion of the other liquid behind. The vapor can then be cooled as it passes through a chamber, condensing it.
Its interesting that in the case of fractional distillation its a simple process but the aim is to do it at a really large scale.
Crude oil is a huge composition of hydrocarbons all with different boiling points. The output fuel is some extraction of hydrocarbons of a given range from this oil.
Fractional distillation is kind of like a ladder of heating to boiling points and ‘drawing’ off hydrocarbons This video details the bottle cap technique: https://www.youtube.com/watch?v=2xzYf8IL_FE.
The ‘point’ of the filtration and hydro treatment steps is to be left with just a composition of hydrocarbons. Oxygen is removed in this second step. The by products are CO/CO2/H2O.