Sliding Vane Pump Technology is Ideal When Transporting and Handling Biodiesel
By Tom Stone
Introduction
Buoyed by the passage of the Energy Policy Act of 2005, biodiesel has earned a respected place within the alternative motor fuels industry in the United States, with the Department of Energy at one point calling it the country’s “fastest-growing alternative fuel.” In 2006, the Congressional Budget Office and the U.S. Department of Agriculture confirmed that biodiesel is the lowest-cost alternative-fuel option for meeting EPAct 2005’s alternative-fuel use requirements.
All of this high praise came as a result of the fuel’s many positive characteristics, including ready access to easily renewable feedstocks, high energy efficiency, higher energy content when compared to other alternative fuels, compatibility with the existing fuel-distribution infrastructure and ability to reduce green-house-gas emissions.
According to the National Biodiesel Board (NBB), the national trade association that represents biodiesel in the United States, domestic production of biodiesel rose rapidly and peaked in 2008 at 691 million gallons, up sharply from the 112 million gallons produced in 2005. The nation’s biodiesel consumption experienced a similar sharp increase, rising from 75 million gallons consumed in 2005 to 690 million gallons consumed in 2008. The consumption of biodiesel comes in either its pure B100 form, or as a blending agent with petroleum diesel fuel, most popularly at a 2% (B2), 5% (B5) or 20% (B20) blending ratio.
Though the NBB’s preliminary figures show a decrease in domestic production in 2009 to 490 million gallons as the industry does a bit of retrenching (2009 consumption data is not yet available), indications are that the fuel will continue to remain a robustly viable alternative to, or blending agent with, traditional petroleum diesel fuel.
The Challenge
No matter the amount of biodiesel produced and consumed in the United States, one of the main challenges found in incorporating it into the nation’s motor-fuel pool is one of transportation. This challenge is divided into two areas. The first is one of logistics. Since most biodiesel is produced in relatively remote areas, the most common shipping methods for biodiesel are railcar and transport truck.
These modes of transportation lead us to the second part of the challenge–the equipment that is used to transfer the biodiesel from production plant to railcar or truck, and from railcar to truck. Because biodiesel has better lubricating properties and a much higher cetane rating than traditional low-sulfur diesel fuels, the use of biodiesel in diesel engines can reduce fuel-system wear and increase the life of the fuel-injection equipment that relies on the fuel for its lubrication.
However, while biodiesel use can improve engine performance for the end-user, its properties can have a deleterious effect on the equipment that is used to transport it from point to point along the supply chain. With that in mind, studies have shown that although B20 is well-suited for use with most diesel technology, B100 and other higher biodiesel blends require special handling with equipment that has been engineered to be compatible with the fuel. Specifically, B100 will degrade, soften or seep through hoses, gaskets, seals, elastomers, glues and plastics that have been made with nitrile rubber, polypropylene and polyvinyl materials. Non-metallic materials that have been shown to be compatible with B100 include PTFE, fluorocarbons (FKM), high-density polyethylene (HDPE), fluorinated plastics and nylon. Metals that are compatible with B100 include ductile iron, stainless steel, carbon steel and aluminum, while brass, bronze, copper, lead, tin and zinc are incompatible.
The Solution
Taking into consideration the material-compatibility concerns that are inherent in the handling and transportation of biodiesel, especially in its higher concentrations, Blackmer®, Grand Rapids, MI, USA, which is a member of the Dover Corporation’s PSG, Redlands, CA, USA, has developed a complete line of sliding vane pumps that have been proven to be the most efficient, reliable and environmentally safe options when transporting biodiesel.
The key pump components to consider when handling biodiesel are the elastomer seals. All Blackmer sliding vane pumps for biodiesel applications feature elastomer seals that allow for compatibility with all biodiesel blends. Existing FKM elastomers have been upgraded to a high-grade compound to allow for much broader material compatibility. These elastomers are also UL-listed and approved for all biodiesel blends, including B100. The enhanced FKM seals also ensure proper sealing and volumetric output, even after significant in-service time.
Even before the introduction of the upgraded, biodiesel-compatible elastomers, Blackmer’s sliding vane technology offered high efficiency and low maintenance advantages over traditional gear and lobe pumps when it came to handling thin liquids like biodiesel. These are important factors in today’s era of rising energy costs, lean personnel staffs and high demand for increased profitability.
The vanes that slide into or out of slots in the pump rotor are one of the secrets behind a sliding vane pump’s enviable operational characteristics. When the pump driver turns the rotor, centrifugal force, push rods and pressurized fluid causes the vanes to move outward in their slots and bear against the inner bore of the pump casing, forming the pumping chamber. As the rotor revolves, fluid flows into the area between the vanes (hydraulic segments) 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 squeezed out into the discharge piping. Therefore, each revolution of a sliding vane pump displaces a constant volume of fluid, maintaining high volumetric efficiency and resulting in a minimal variance in pressure and the minimization of energy-wasting turbulence and slippage.
In addition to the advantages offered by sliding vane operation, all Blackmer sliding vane pumps place seal and bearing life as the primary design emphasis, leading to a pump that eliminates the most problematic challenges of light-liquid transfer. This also gives the pumps seal and bearing integrity, the ability to offer flow rates from 1 gpm to 2,300 gpm, superior self-priming, line-stripping and suction capabilities, and maintenance characteristics that allow the pump to be completely rebuilt with the piping attached.
Application Examples
Blackmer sliding vane pumps have been used in a number of biodiesel applications, both big and small, by producers who wish to maximize the return on their biodiesel production, while also ensuring that the fuel is delivered in a safe and effective manner. For example:
■ In 2002, Dennis K. Burke, Inc., Chelsea, MA, USA, became the first supplier of biofuels, including biodiesel, in the Northeast. To ensure the safe and efficient of its entire product line—which includes gasoline, low-sulfur diesel, biodiesel, heating oil, kerosene, racing fuels, motor oils and other lubricants—Dennis K. Burke has outfitted its 70-plus truck fleet with Blackmer TXD2.5A Series and TXD3E Series sliding vane transport pumps that have been designed for use in truck-mounted delivery applications of all types of motor fuels, including biodiesel.
■ Like many biodiesel pioneers, Scott Johnson began making biodiesel in his garage in 2005. Since then, his dream has grown into the GEN-X Energy Group, Inc., Burbank, WA, USA, and a biodiesel production plant that could someday produce as many as 40 million gallons of the alternative fuel per year. To help keep the GEN-X operation running smoothly, Johnson relies on Blackmer XL Series sliding vane pumps for high-speed truck loading and transfer. In addition, the plant also uses Blackmer ProVane® Motor Speed Sliding Vane Pumps for methanol recovery during the production process. ProVane pumps feature a hydrodynamic journal bearing that eliminates shaft-to-bearing contact, resulting in higher mechanical efficiency and reduced energy costs.
■ Cincinnati-based Peter Cremer North America LP became the first BQ-9000-certified producer of biodiesel in the United States in 2002, and in 2006 completed a plant expansion that allows it to produce 30 million gallons of biodiesel per year. To meet this demand, Peter Cremer utilizes Blackmer NP2 and NP4 Series sliding vane pumps for a wide variety of plant operations, from moving product from production to storage, to unloading raw materials from railcars, to loading finished products onto trucks for delivery.
■ In 2005, the Minnesota state legislature passed a mandate that all diesel fuel contain at least 2% biodiesel. Since then, as much as 15% of the deliveries made by Kane Transport, Sauk Centre, MN, USA, now consist of biofuels, with a significant portion being biodiesel from B2 to B100. With an expansive network of 11 company-operated terminals and a rolling fleet consisting of nearly 200 tractor trucks and more than 250 transport trailers, Kane Transport has turned to Blackmer TXSD3E Series sliding vane pumps for all of its biodiesel deliveries.
Conclusion
With biodiesel production and consumption continuing to be a major component of the motor-fuel pool in the United States there is a profound need for materials and equipment that are capable of handling its production, transportation, handling and storage. With a century-old history of efficiently and safely handling thin liquids, sliding vane technology from Blackmer is the obvious choice for the pumping requirements found in a biodiesel plant, tank truck and railcar fleet, or storage facility.
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Inside Sliding Vane Pump Technology
The vanes that slide into or out of slots in the pump rotor are one of the secrets behind a sliding vane pump’s enviable operational characteristics. The pump’s rotation draws liquid in behind each vane, through the inlet port and into the pumping chamber. As the rotor turns, the liquid is transferred between the vanes to the outlet where it is discharged. Each vane provides a positive mechanical and hydraulic displacement of the liquid. Vanes are actuated by three forces:
1) centrifugal force from the rotor’s rotation
2) push rods moving between opposing pairs of vanes, and
3) liquid pressure entering through grooves and acting on the rear of the vanes
Each revolution of a sliding vane pump displaces a constant volume of fluid; variances in pressure have a negligible effect. Energy-wasting turbulence and slippage in the pump are minimized and high volumetric efficiency is maintained. The sliding vane technology also results in superior priming and suction capabilities, making the pumps the perfect choice for line-stripping, the evacuation of heels and pumping from underground or top unloaded storage tanks. Sliding vane pumps for biodiesel applications are available with capacities from 1 gallon per minute to 2,300 gallons per minute.