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Case Study:

The method of using a split pipe weir system is extremely inefficient and recovers mostly water (98-99%) and very little oil (1-2%).  Therefore pushing higher volumes of water with surface and suspended hydrocarbons from the primary into the secondary separation chamber where chemicals are used to knock out higher volumes of hydrocarbons.

Over the past 15 years environmental standards for the discharge of refinery effluent back into the environment have become extremely stringent and are currently at 15 ppm.  This can put a lot of pressure on oil companies to comply.  Aqua-Guard recognized the need to assist refineries increase their efficiencies in effluent discharge but also saw a value in a higher level of oil recovery.  Therefore Aqua-Guard proposed to assist refineries meet their needs with the installation of their oil skimming systems equipped with RBS TRITON™ skimming technology which recovers up to 98% surface oil therefore increasing the efficiency of the primary separation stage by almost 99%.

Industrial wastewater found in the internal collection sewers and basins of oil refineries contain valuable petroleum bi-products and raw crude oil.  Installing this technology would help recover these valuable products and return them into the refining process. Besides the financial return, there is a positive benefit to the environment by reducing the amount of hydrocarbons in the effluent waste water.

For example several skimmers were installed in Chevron’s Burnaby Oil Refinery in September of 2008 and have since been in service recovering valuable hydrocarbons 24 hours/day, 365 days/year. The skimmers are serviced only twice a year, primarily for maintenance purposes.

The Problem:
In 2008, Chevron approached Aqua-Guard to design a custom solution for a Chevron Refinery to replace the outdated and inefficient pipe weir skimming system for their API separation basins.   With the ever-stringent regulations Chevron were eager to upgrade their system to fully meet all effluent discharge requirements at the time.

In order to cut down the amount of chemicals used in the secondary processing stage, Chevron asked Aqua-Guard if they could design and supply a system that would remove most of the surface hydrocarbons in the primary separation ponds, therefore reducing the amount of carry over hydrocarbons into the secondary treatment ponds.

The Solution:
Working with Chevron they designed a specific system for installation in the primary oil water separation stage of aging API separators.  These industrial skimmers would have to be of all stainless steel construction for the highly corrosive API environment.  The system would rely on adhesion of oil to the surface of a rotating stainless steel disc.  As the disc insert rotates through the oil/water surface, the oil would adhere to the surface and be removed by a scraper.  The product would collected in a common sump and pumped back into the refinery system for use.  Discs could be interchanged with either drums or brushes for recovering various oil types that maybe encountered inside the API separator pond.

Since the site had an abundant air power source the systems were designed with pneumatics in mind.  The unit would have to be 100% powered pneumatically from the oil skimmer head and the rotating stainless steel disc recovery system to the double diaphragm pump used to recover the product.
Therefore it was decided that a stainless steel, floating oil-skimming system would be installed in each primary separation pond.  Each skimmer being capable of recovering up to 63m3/h of surface hydrocarbons.

The skimmers were paired with 2 stainless steel pneumatic pumps mounted externally. Each Pump capable of 20m3/h of hydrocarbon recovery.
The skimmers had to be self-adjusting in order to adapt to the fluctuating basin levels thus reducing wastewater circulation and maximizing valuable oil recovery. Other benefits would include the skimmer¹s ability to recover virtually any viscosity oil along with being fully automated, which would reduce operating costs for Chevron.


The Result:
From time of installation in 2008 to early 2014, Chevron has enjoyed a trouble free system operating for over 50,000 hrs.   The installed oil-skimming systems have been running 24/7 since being first installed in 2008, collecting a wide range of oil viscosities during the operation. The estimated maximum hydrocarbon recovery of these systems since inception 870,000 cubic meters of recovered product returned back to the customer for re-processing.  A huge savings for Chevron with a positive environmental impact.

Shell oil refineries in Asia and other national oil companies in Latin America now also employ the patented oil skimming technology in their industrial processes to help optimize their refining operations thus putting profits back into the refinery all the while assisting the companies to conform to local environmental standards.

These systems also are able to recovery ultra heavy oil.  Heavy oil tests have been conducted and witnessed by Det Norske Veritas (DNV). These tests followed the ASTM F631-99 ³Standard Guide for Collecting Skimmer Performance Data in a Controlled Environment². The viscosity of the oil used during these recovery tests was 195,959 cSt.

Brush recovery modules in combination with an onboard positive displacement lobe pump proved to be the most effective method of recovering such viscous oil.



Since this article was written Aqua-Guard has launched and supplied a new RBS TRITON™ 100 industrial oil skimming system capable of recovering up to + 100 m3/h (629 bbl./h).  These systems have been specifically designed for export to countries where higher amounts of oil are present in their primary separation ponds and require higher recovery rates from skimming systems.

Although many refineries around the world still use the old split pipe weir skimming systems they are seeing the benefits of upgrading their systems to include new state of the art oil skimming technology in order to turn once thought of waste to profit along with helping to protect the environment.

About Aqua-Guard

Aqua-Guard provides a range of state-of-the-the-art oil spill response solutions including the URO Skimmer System and the RBS TRITON™ range of oil skimmers—all built on Aqua-Guard’s patented RBS TRITON™ technology to deliver some of the highest efficiency and recovery rates in the industry.