7/30/2019 Oil Stages

1/1 Pearson Longman 2008 www.pearsonlongman.com/technicalenglish

1 Study this diagram of the oil distillationprocess. Circle T (true) or F (false) in thedescription.

Crudeoilisheatedandpumpedintothecolumn(1.T/F).Whenthishappens,allthecrudeoilevaporatesandthevapour(orgas)risesthroughthecolumn(2.T/F).Asthevapourgoesupthecolumn,thetemperaturedecreases(3.T/F).Allthevapourromthecrudeoilfowstothetopothecolumnandleavesitthroughapipe(4.T/F).Whenthetemperatureallstobetween175Cand325C,someothevapourcondensesintoliquidkerosene(5.T/F).Thissubstancecondensesatahighertemperaturethannaphtha.

(6.T/F).

2 Read the description of the distillation processand answer the questions on the next page.

The oil rening process: fractional distillation

Crude oil (also called petroleum) is a mixture o dierent hydrocarbons. Many useul products can be made rom

these hydrocarbons. But rst the useul ones must be extracted rom the crude oil and separated rom one another.

How is this done?

The dierent hydrocarbon components o crude oil are called ractions. The ractions are separated rom one another

using a process called ractional distillation. This process is based on the principle that dierent substances boil at

dierent temperatures. For example, crude oil contains kerosene and naphtha, which are useul ractions (naphthais made into petrol or cars, and kerosene is made into jet uel). When you evaporate the mixture o kerosene and

naphtha, and then cool it, the kerosene condenses at a higher temperature than the naphtha. As the mixture cools,

the kerosene condenses rst, and the naphtha condenses later.

This is how ractional distillation works. The main equipment is a tall cylinder called a ractionator (or ractional

distillation column). Inside this column there are many trays, or horizontal plates, all located at dierent heights.

Each tray collects a di erent raction when it cools to its own boiling point and condenses.

The crude oil is heated to at least 350C, which makes most o the oil evaporate. The fuid then enters the column.

As the vapour moves up through the ractionator, each raction cools and condenses at a dierent temperature. As

each raction condenses, the liquid is collected in the trays. Substances with higher boiling points condense on the

lower trays in the column. Substances with lower boiling points condense on the higher trays.

The trays have valves, which allow the vapour to bubble through the liquid in the tray. This helps the vapour to cool

and condense more quickly. The liquid rom each tray then fows out o the column.

gases(e.g. propane)

boil at 600 C