(114b) LPG Recovery from the Off-Gas of Several Aromatics Plants By Means of a Top DWC at a Major Far East Petrochemical Complex.

As part of the planned expansion of the Petrochemical Complex, HTC had to install a new grass roots Gas Plant to process the Off-Gas coming from several Aromatics Units of the Petrochemical Complex.

Two major goals did drive the project:

• Minimize the Off-Gas quantity routed to the Fuel Gas System to avoid any potential bottleneck for the future operation.
• Produce an on-spec Propane stream suitable for recycling it as feedstock to the Cracker Unit.

One major constraint had to be considered: the plot area for the new Gas Plant had to be minimized since the petrochemical complex was already congested.

Several options were investigated, among others the conventional layout with three columns in series: Absorber/De-Ethanizer; De-propanizer; De-Butanizer.

This solution could produce on-spec Propane, but the recovery was lower than desired. Moreover the required plot area was consistently higher than available. HTC decided to consult with Sulzer GTC Technology, nowadays Sulzer CFCL.

Sulzer CFCL designed the entire Unit including the gas compression and the fractionation sections. For the fractionation section, the GT-LPG Max^TM advanced separation technology was selected. It consists of one single column equipped with a Top Dividing Wall and high-performance fractionation trays. Thanks to the reduced number of equipment, it was possible to install the new Gas Plant in the designated area of the petrochemical complex while providing high Propane recovery that suits HTC’s requirement.

The Unit is running since more than 2 years, it allows for more than 88% Propane recovery with a purity as high as 94%.

This paper will discuss the project from the feasibility study to the commissioning of the Unit and the plant feed-back data.