Pump Technologies Provide Greater Efficiencies

By Tom Stone | July 08, 2008
As national gasoline prices continue to rise, the national media has focused its attention on the hardships these historically high prices have foisted on the motoring public.

However, the price increases have also had a profound impact on the people and companies that move the product from the refinery through the many twists and turns of the supply chain until it reaches the consumer's gas tank. Simply put, the current pricing trend is transforming all areas of the petroleum industry and petroleum jobbers, terminal operators and marketers are being forced to find ways to wring costs out of their businesses.

On top of that, the task facing today's jobbers, terminal operators and retailers is complicated by the fact that the motor fuel supply is becoming increasingly complex with the addition of new fuels, reformulations of old fuels and federal mandates governing the use of alternative fuels. One alternative fuel that has received increased play since the dawn of the new century is ethanol, which has been backed by a high-profile, auto-industry-driven advertising campaign and support from legislators in Corn Belt states where most ethanol feedstocks are grown and harvested.

In reality, ethanol has been a prominent part of the nation's motor-fuel supply chain since it began being used as a 10 percent oxygenate and octane booster in unleaded gasoline nearly 30 years ago. More recently, the big push for increased ethanol use is in its 85 percent ethanol/15 percent gasoline form, known as E85. While the E10 that's been used in the country's motor fuel pool for three decades does not require any engine modifications, E85 can only be used in flexible-fuel vehicles that have been specifically designed for that task.

Looking beyond the consumer impact, terminal operators face a variety of questions that they need answers to before they can start moving ethanol through their plants. Because of its unique properties, ethanol-blended fuels generally cannot be shipped by a petroleum product pipeline due to operational issues, mainly ethanol's affinity for water, which is a byproduct found at some level in all petroleum pipeline systems. Thanks to that—and coupled with the fact that the majority of ethanol-production facilities are located near the sources of their feedstocks in the Midwest—most ethanol (and other biofuels) are transported chiefly by truck, barge and rail, creating an increase in terminal traffic and the need for more efficient plant processes. For example, common E10 requires only one incoming truck loaded with ethanol for every 10 outgoing trucks leaving the terminal with E10. By contrast, E85 necessitates 8.5 incoming loads of ethanol for every 10 outgoing loads of finished motor fuel.

Regardless of how the various feedstocks and finished motor fuels enter and exit the terminal, there is no question that processes must be found to streamline the loading and unloading process, efficiently strip lines and clear tanks and transports of every possible drop of valuable product, eliminating waste by ensuring more precise blending consistency in biofuels operations.

Sliding Vane Technology Offers Efficiencies
As petroleum terminal operators modify and expand existing facilities or upgrade newly acquired terminals in order to handle higher volumes and new alternative fuels, the search for greater efficiency, lower maintenance costs, better line-clearing capabilities and more accurate blending processes is prompting many companies to take a new look at a long established and proven pumping technology. The sliding vane pump's concept has been around for more than a century and provides the essential solution for streamlining loading/unloading operations, optimizing line stripping and transport tank clearing, and offers volumetric consistency in blending applications.

The concept of sliding vane pumps is simple, as is the comparison to the competing technologies of centrifugal pumps and internal gear pumps. Centrifugal pumps employ only one force—increased velocity—to move product. Increased product movement thus becomes a function of increased speed. In turn, higher speeds require engines with more horsepower and greater power consumption. At the same time, centrifugal force is an inefficient mover of any residual product remaining in the line.

Internal and external gear pumps provide a mechanical solution for moving product. Therefore, as soon as the pumps are placed in service the gears begin to wear and flow rates drop. Additionally, due to the wear, volumetric consistency may be compromised in blending applications.

Sliding vane pumps are designed with unique "self-adjusting" vanes that allow them to maintain near-original volumetric performance during the life of the pump—meaning these pumps are not subject to the efficiency-robbing slip that occurs from wear in gear pumps. This feature also ensures the kind of volumetric consistency required to meet biofuel-blending standards. Compared to a centrifugal pump, a sliding vane pump requires 25 percent to 30 percent less horsepower to move the same volume of product. These pumps have long been common in the transportation industry and are increasingly installed in new construction of biodiesel and ethanol production plants. As terminal operators refit and expand, sliding vane pumps are emerging as an effective and efficient technology for petroleum bulk plant and terminal operators.

Sliding vane pumps have a series of vanes (normally made of a nonmetallic composite) that freely slide into or out of slots in the pump rotor. When the pump driver turns the rotor, centrifugal force, push rods and/or pressurized fluid causes the vanes to move outward in their slots and bear against the inner bore of the pump casing forming pumping chambers. As the rotor revolves, fluid flows into the area between the vanes (pumping chambers) when they pass the suction port. This fluid is transported around the pump casing until the discharge port is reached. At this point the fluid is pushed out into the discharge piping.

Each revolution of a sliding vane pump displaces a constant volume of fluid. Variance in pressure has minimal effect. Energy-wasting turbulence and slippage are minimized and high volumetric efficiency is maintained. Sliding vane pumps are also self-adjusting. As a result, the system eliminates fluid slip that wastes energy in other types of pumps.

Further, since the vanes constantly adjust to accommodate for wear, unlike gear pumps that are not self-adjusting, sliding vane pumps maintain near-original and consistent volumetric performance over time. Since each revolution of the pump positively displaces a constant volume of product, bulk-plant operators know—by monitoring speed and flow rate—that they have delivered the exact amount of fuel their customers have ordered. Sliding vane pumps also provide a tremendous amount of suction capability, which benefits terminal operators by stripping lines and leaving no heel in tankers.

Because of the design of the pump's rotor and independent sliding vanes, sliding vane pumps are easy to maintain at peak performance levels and, if necessary, can be completely rebuilt with piping attached. Worn vanes can be replaced, by removing the outboard head assembly, sliding out the old vanes, inserting the new ones and reinstalling the head. In a matter of minutes, the pump can be back in operation. Simple vane replacement also requires no special tools.

For owners of petroleum terminals, the result is optimized operating efficiency, more consistent blending, less power consumption, repair, maintenance, and wasted or contaminated product, more speed and precision in loading and unloading. With bulk plants already challenged by high oil prices and required to wring more costs out of their operations—and facing the prospect of handling a more diverse mix of precisely specified fuels—sliding vane technology provides the best available solution.

Although vane pumps may require a higher upfront investment than other types of pumps, they measurably reduce a terminal's operating and lifecycle costs to produce a justifiable return on investment. Yet the paradigm of making upfront investments in return for long-term savings has become the norm throughout much of the American economy.

The U.S. construction industry, for example, has in recent years shifted increasingly to the concept of "green building" and away from its traditional focus on initial capital costs. The petroleum industry, which itself aspires to be "green," can do no less.

In summary, rising oil prices have increased the cost for petroleum wholesalers to finance their inventories and accounts receivable, creating a need to squeeze ancillary spending out of their operations by boosting efficiency and eliminating waste. At the same time, the high fuel prices are also leading to increased market shares for biodiesel and ethanol, requiring petroleum-terminal operators to face a reality that indicates that U.S. production of ethanol and other biofuels will triple between now and 2013. This will force many terminal operators to either modify or expand their storage facilities and traffic capacity, or get out of the game. Compliance with government and industry standards for fuel specifications will only become stricter in that time, increasing the demand for precise blending at the terminal.

With a need to boost operating efficiencies and the prospect of upgrading or expanding terminal facilities, growing numbers of bulk plant operators are investigating sliding vane pump technology and discovering they can optimize performance and get measurable returns on their investments. A concept proven over a 100-year period, sliding vane pumps consume less power, require less maintenance, offer high suction that helps clear lines, tanks and transports, and deliver precise volumetric consistency in both loading/unloading and blending applications. In short, sliding vane pumps provide a viable, efficient solution for the challenges of operating a petroleum bulk plant in today's marketplace.

Tom Stone is the director of marketing for Grand Rapids, Mich.-based Blackmer. Reach him at stone@blackmer.com or (616) 248-9252.