Recovery of heavy hydrocarbons or LPG from refinery gas streams can significantly increase the added value of their products and enhance their profitability and overall competitiveness.

State of the art processing technology and equipment are essential for efficient and reliable operation.  Maximizing LPG recovery into the product streams improves  refining margins.

Light ends recovery process

The light ends recovery unit uses absorption and distillation steps to remove propane and heavier components from refinery gas streams prior to their use as fuel gas.  The recovered C3+ components are then separated and used in various product streams.  

In the absorption step, naphtha and kerosene are used to absorb the  heavier hydrocarbons producing fuel gas and the heavier liquid stream. The naphtha rich liquid product exiting the bottom of the absorber is fed into a series of columns which removes lighter products stage by stage. 

These sub-columns are named in a self-explanatory way

• Deethanizer:  Ethane recovery
• Depropanizer:  Propane recovery
• Debutanizer:  Butanes recovery
• Deisobutanizer:  Separates the isobutane overhead and normal butane as a side draw

The remaining C5/C6 fraction is generally used for gasoline blending, while the heavy naphtha fraction goes to the catalytic reforming to produce high octane gasoline.

One or more of these light ends columns can become a bottleneck in refinery expansion, reconfiguration or feedstock change.  However, these can be alleviated with modern upgraded internals and/or rerated rotating equipment.