Both modes of gear pumps possess some advantages that are similar to sliding vane pumps—nonpulsing, self-priming and dry-run capability; ability to handle thin liquids at varying pressures; and ease of maintenance.
But because of the style of operation, gear pumps wear as the pump’s gears mesh, or come into contact with each other, to move fluid. This increases the internal pumping clearances, reducing flow capacity that results in less fluid pumped per rotation while simultaneously increasing slip within the pump. To compensate for these larger clearances the pump speed or size must be increased, which can result in higher energy consumption and accelerate the pump’s wear.
The alternative in this gear-wear scenario is to tolerate a lower level of pumping capacity until the pump’s performance drops to an unacceptable level.
However, the gear wear can often go undetected by the operator, which can sap the pump of efficiency—both energy- and performance-related—before the necessary maintenance can be performed.
Conversely, because the self-compensating vanes in the sliding vane pump continuously adjust for wear, they can allow the pump to maintain near-original efficiency and capacity throughout their life. The pump speed also does not need to be increased over time, making sliding vane pumps natural energy-savers.
If the sliding vanes wear out or are damaged, replacing them is quick and easy. Vane replacement can be accomplished by simply removing the pump’s outboard head assembly, removing the old vanes, inserting new ones and reinstalling the head, all without the need for special tools. Also, it is not necessary to remove the pump from the system. All replacements can be completed while the pump remains in line.
Future Energy Consumption Predictions
To the surprise of probably no one, in its International Energy Outlook 2017 report, the U.S. Energy Information Administration (EIA) predicted world energy consumption would rise 28 percent between 2015 and 2040, from 573 quadrillion British thermal units (Btu) in 2015 to 736 Btus by 2040. This extrapolation is supported by the EIA’s “Reference case,” which “assumes continual improvement in known technologies based on current trends and relies on the views of leading economic forecasters and demographers related to economic and demographic trends for 16 world regions based on Organization for Economic Co-operation and Development (OECD) status.”
What is the OECD? Founded in 1961, the OECD is an intergovernmental organization that is committed to stimulating economic progress and world trade. There are 36 OECD countries, including the United Kingdom and the United States.
Related to the rate of growth in world energy consumption, the EIA predicted that the global industrial sector—for this article’s purposes, the manufacturing, mining, agriculture, and construction industries—will continue to account for the largest share of energy consumption through 2040. At an annual growth rate of 0.7 percent, global industrial energy use will increase a total of 17.5 percent from the 240 quadrillion Btus in 2015 to 280 quadrillion Btus by 2040.
The main reason behind this steady increase in energy consumption should be equally obvious—the world’s population continues to increase, with the United Nations’ Department of Economic and Social Affairs saying that the current population of 7.6 billion people will expand to 8.6 billion in 2030 and 9.8 billion by 2050. This consistent population growth is most significant in developing, non-OECD countries, and is being driven by improvements in infrastructure, food production and health care that have created a better standard of living for many of those countries’ residents.
Today, the task of outfitting an industrial facility with pumps is so much more complex than picking a technology, turning it on and watching it go.
With demanding production schedules, tight operating budgets and environmental-safety concerns to consider, facility operators must identify and implement pumping technology that can reliably satisfy these demands, which can appear to be at odds with each other.
The operational characteristics of sliding vane pumps have held many advantages over centrifugal pumps and other PD-pump technologies in the areas of maintaining flow rates and optimizing energy efficiency—especially if the application requires the handling of nonabrasive liquids at temperatures less than 500 F (260 C) and with viscosities less than 22,500 cP.