Recommendation of process routes for the sepration of LPG - Essay Example

To separate these two constituents, several processes can be used. This method involves the recovery and increase in the purity of the light hydrocarbons butane and propane from their mixture in liquid petroleum gas. It is based on the distillation of the gas by controlled heating and cooling, by taking gain of the diverse boiling points of the hydrocarbons. Fractionating columns are used with labels if the hydrocarbon is separated by evaporation. Liquid petroleum gas composition of propane and butane which makes up to 40% natural gas is extracted as a liquid mixture in a fractionating column (Zlokarnik, 2002).

After its extraction from natural gas, the refrigerated liquid petroleum gas is passed through an absorber column where it is mixed with lean oil at a temperature of 238 degrees Celsius to allow for the absorption of the liquid petroleum gas products. This process is accelerated by elevated pressure and low temperature and the refrigeration of the liquid petroleum gas is ensured by using a closed loop circulation of a refrigerant in centrifugal compressors. The liquid petroleum gas is precooled before it enters a de-ethanizer column with a pressure lower than the pressure of the liquid petroleum gas.

In the de-ethanizer, ethane and other lighter components in the liquid petroleum gas are removed. A constant temperature is maintained in the column by using a reboiler placed at the bottom of the fractionating column to supply heat. The overhead vapour is recycled to recover any escaped propane from the evaporated gas. The residue is then passed through a rich oil still column where the lean oil is separated using distillation. The liquid petroleum gas that is separated is condensed in a reflux condenser and is then directed into fractionating columns.

Depropanizer and debutanizer systems are used to separate the stabilized