Crude Oil: A Case Study

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Ulrich Eibl details a rail car unloading solution with the latest generation pumps

When a major industrial rail terminal operator in the USA initially wanted to improve the noise level and operation of a rail car unloading pump for crude oil at its facility it decided to opt for 4NS Notos multiple screw pumps using double mechanical cartridge seals with an external flushing system.

The tank terminal design included a rail car unloading rack employing three gear pumps. Because these pumps were sensitive to changing weather conditions, they would vibrate, which resulted in noise. One pump was extremely noisy (it was measured at greater than 100dB), prompting the terminal manager to contact a Netzsch distributor to investigate pump replacement solutions.

A visit was made to the rail car unloading facility to get an overview of the system requirements.

During the visit, it was discovered that the terminal not only wanted to replace that specific noisy gear pump, but all three gear pumps used on the rail car unloading rack. This rack is basically a fixed structure, such as a platform or gangway allowing workers to safely access the rail car at the height needed for their application. The initial quote was for a solution that was quiet, with no leak, no vibration and offered a faster unload operation; but the order was not quickly placed by the customer.

After a time, Netzsch learned that the terminal was in the process of designing two more unloading racks with two pumps per rack and so would require six new pumps. Consequently, another visit was scheduled to discuss the expansion project and what solution Netzsch could offer.

New operating parameters were established. These included a greater viscosity range of the crude oil product and a desired higher flow. The API grade of the incoming crude oil at this terminal could be as low as 10 API and as high as 52 API, which is a significant variation. This variation in product viscosity would also cause changes in the system pressures during unloading. Temperature changes could also change the viscosity of the product. Coupled with the fact that the customer wanted to strip the rail cars, the Notos 4NS multiple screw pump, a positive displacement pump with no metal to metal contact was definitely the best pump type for this crude oil rail car unloading project. Along with this, the pump had to meet API 676 requirements.

As a result, a new pump choice, a Notos 4NS pump using double mechanical cartridge seals with an external flushing system, was chosen as the best pump selection for the rail car unloading application. Stripping railcars, the process of draining each rail car until all fluid is removed, can cause a pump by itself to run dry for short periods of time. By employing a double mechanical cartridge seal the pump can run dry without damage to the pump seals as they are lubricated by an external seal flushing system.

With all these benefits, the customer selected Netzsch to provide the Notos 4NS pumps for its rail car unloading project.

Ulrich Eibl is with Netzsch

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