CRUDE OIL DISTILATION

INTRODUCTION

Crude Oil is a naturally occurring mixture, consisting predominantly of hydrocarbons and/or of sulfur, nitrogen, and/or oxygen derivatives of hydrocarbons, which is capable of being removed from the earth in a liquid state.

Crude oil comes from the ground, which contains variety of substances like gases, water, dirt, minerals. Basic types of crudes are asphaltic, naphthenic, or paraffinic, depending on the relative proportion of these types of hydrocarbons present.

Distillation

Preliminary Distillation

Separation of liquid compounds  by  boiling  point.  For example,  a  mixture  of  two  hydrocarbons  can  be  heated  so  that  the  lower molecular  weight  hydrocarbon  evaporates—if  the  vapor  is  not  allowed  to escape but taken around the corner and cooled down, it can be extracted as a pure liquid. Distillation is a process that uses the difference in boiling points of molecules and petroleum fractions to separate the compounds and streams. (E.W Dean, 1992)

Distillate:

The product of distillation obtained by condensing the vapors from a refinery still, also known as overhead fractions, as distinguished from the non-vaporizing residual components left in the still. In the distillation of a sample, a portion is evaporated; the part that is condensed afterward is the distillate. The distillate or middle range of petroleum liquids produced during the processing of crude oil.

Crude oil processing involves both physical and chemical methods. Mostly the separation is done by physical means and further processing to improve its quality by chemical means. The physical separation process whereby the separation is based on differences of certain physical properties of the constituents such as the boiling and melting points, adsorption affinities and diffusion through certain membranes. (R.N Watkins, 2004)

The important physical separation process which is our main concern here is crude oil distillation. Crude distillation separates raw crude oil feed (usually a mixture of crude oils) into a number of intermediate refinery streams, characterized by their boiling ranges. Each fraction leaving the crude distillation unit is defined by a unique boiling point range. 

PRODUCTS FROM A CRUDE OIL

The products refined from the crude oil can be placed into many categories. These main products are further refined to create materials more common to everyday life, these products are;

Liquefied Petroleum Gases.

Are the mixtures of gases that are most often used in heating appliances, aerosol propellants, and refrigerants.  Different kinds of liquefied petroleum gas are methane, ethane, propane and butane. At normal atmospheric pressure, liquefied petroleum gas will evaporate, it refined at (20-25) ° C. 

  

Gasoline –petrol.

Gasoline is a mixture of paraffin’s, naphthenic, and olefins, it’s boiling point ranges from ( 20-90) ° C   it is easily vaporized , high flammable ,easily ignited and car fuel. 

Naphtha.

Naphtha is refined at a temperature of about (75 – 180)⁰C.

Kerosene and paraffin.

Kerosene is collected through fractional distillation at temperatures between (190-250) ° C. It is a combustible liquid that is thin and clear. Kerosene is most commonly used as jet fuel and as domestic heating fuel.

 

Diesel.

Diesel is produced by fractional distillation between ( 250-350) ° C. Diesel has a higher density than gasoline and is simpler to refine from crude oil. It is most commonly used in transportation in car and large vehicles. (E.W Dean, 1992)