The client refinery operated under a special permit which limited throughput in exchange for certain economic benefits. The rules required that throughput not exceed 75MBPD averaged over a short period. As the refinery was physically constrained to 60MBPD, it could not take advantage of the remaining 15MBPD of permitted throughput. To make matters worse, the refinery had no capacity to make up throughput that was lost for maintenance shutdowns.
Cost Effective Solution
Polaris provided a refinery revamp that allowed an increase in refinery Crude Rate from 60 MBPD to 82 MBPD. The ability to run 82 MBPD allowed the refinery to “catch up” on their permitted average throughput when the average would have otherwise been diminished by outages.
After field work to determine the capabilities of the existing equipment and process modeling, our engineering team developed the most cost-effective solution. The revamp included the addition of a Crude Preflash Column and a Gas Oil Distillation Column. These additions unloaded the existing Crude Distillation and Vacuum Distillation Columns. Preheat train optimization and upgrades obviated the need for modifications to both the Crude and Vacuum Column fired heaters. This strategy also minimized the capital required to reach the desired rates and minimized the operational interruption that replacement of the Crude and Vacuum Columns and their respective feed heaters would have required.
New Design Operation
As crude rate was increased to the unit, the Preflash Column took out products (before the Crude Column) that would otherwise have overloaded the top of the Crude Column. This allowed the top of the Crude Column to continue to efficiently produce naphtha, jet fuel and diesel at the increased crude rates. In exchange for the increased rate, the design allowed the bottom of the Crude Oil Column to run less efficiently resulting in diesel exiting the bottom of the column with the gas oil and residua. Before the project, this large stream would have been routed directly to the Vacuum Column where it would have been too large to process. Instead, the project routed the stream to the new Gas Oil Column first. At the Gas Oil Column, the diesel and some gas oil were recovered from the residua. Now the stream was of a size that the Vacuum Column could efficiently process, and left-over diesel and gas oil was recovered per usual from the residua in the deep vacuum of the column.
Processing Capability Achieved
With minimum capital expense and with minimum interruption to on-going operations, the Polaris design achieved the 82 MBPD processing capacity allowing the refinery to significantly increase overall profitability by taking full advantage of their special operating permit.
Scope of Work
Process / Chemical
Refining, Oil & Gas