Curtailed Throughput

The client refinery historically ran long on Fuel Gas.   The facility was required to flare the excess fuel gas to maintain target refinery throughput and balance.  With the federal 40 CFR 50 Subpart Ja taking effect, the refinery was no longer permitted to vent excess fuel gas to flare.  As such, the refinery was required to curtail throughput to avoid venting excess fuel to flare in violation of the regulation.

 Field Evaluation Results

Polaris conducted a field evaluation of the refinery’s Fuel Gas Process Stream sources, the Fuel Gas System, and the LPG Recovery systems within the plant.  The field work identified a multitude of fuel gas streams that were rich in LPG.  Our engineering team developed a design to gather these streams and route them such that the LPG could be recovered while the remainder was routed back to fuel gas.  In addition, field testing revealed opportunities to optimize fuel gas treating units such as the Saturated Gas Plant (Sat Gas).  Optimization of the Sat Gas Plant not only removed BTU’s and gas volume from the fuel has system, but also recovered it as saleable product: LPG.  As with the Sat Gas Plant, field work revealed that the refinery’s Unsaturated Gas Plant (Un-Sat) also needed to be optimized to recover additional LPG.  Finally, the FCCU Un-Sat Plant was found to be bottlenecked.  Our engineers identified the bottlenecks and provided the engineering for de-bottlenecking.  This de-bottleneck included a new, upgraded FCCU Absorber and Stripper designed by Polaris engineers.

Increased Profitability

The optimization of LPG recovery in the Sat Gas and Un-Sat Gas Plants, in conjunction with the de-bottlenecking of the FCCU Gas Plant Debottleneck brought the Refinery Fuel Gas System back into balance.  This brought an end to the curtailment of throughput for the purposes of complying with the Subpart Ja recommendations and it also increased profitability by capturing as product LPG that otherwise was burned.  The increased LPG and Propylene recovery and production alone paid for the entire project.

Scope of Work

Process / Chemical




Refining, Oil & Gas