Fractional distillation sim
Crude oil is heated to about 350 °C and fed in near the bottom of the column, which is hot at the bottom and cool at the top.
Fractional distillation · covers the GCSE, IGCSE, O-Level topic
What the sim shows
Crude oil is heated to about 350 °C and fed in near the bottom of the column, which is hot at the bottom and cool at the top. The vapour rises; each hydrocarbon condenses on the first tray that is at or below its boiling point and is drawn off there. Refinery gas never condenses and leaves the top; bitumen never boils and is tapped off at the base. Air is cleaned, then compressed, cooled and expanded until it is a liquid at about −200 °C; in the column it is warmed slowly. Nitrogen (−196 °C) leaves the top as a gas, argon (−186 °C) condenses on a tray part way up, and oxygen (−183 °C) stays at the bottom as a pale blue liquid. All three leave at the same time, at different heights. How the numbers are worked out: the fractions, their carbon numbers, boiling ranges and uses are the lesson's. The lesson's naphtha ends at 150 °C and kerosene starts at 160 °C; a hydrocarbon boiling between the two condenses with the naphtha here. The column's temperature is this desk's estimate: a straight line from the feed to the top tray, 350 °C to 40 °C for crude oil and −183 °C to −194 °C for air. Each tray stands where that line equals the lowest boiling point of its fraction, so the trays read 300 °C, 250 °C, 160 °C, 75 °C, 40 °C; with air the same trays read −184.8 °C, −186.5 °C, −189.7 °C, −192.8 °C, −194 °C. Boiling points of the gases and air's make-up are standard data; their uses are standard ones, not from the lesson. A real column has dozens of trays and draws each fraction from one of them; this one shows only the five draw-off trays. The particles are a picture, not a count: each fraction is drawn equally often, and argon about eight times as often as its 1%.
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