How the Right Pump Brings Efficiency and Much Greater Energy Savings
Mon, 02/26/2007 - 5:21am
The latest design advancements in sliding vane positive displacement pump technology can reduce energy consumption while optimizing performance. Here's a review of what's possibleBy Bill Bohr
Just the Facts About Key InnovationsTwo energy-saving innovations applied to sliding vane technology are as follows:
One is a hydrodynamic journal bearing found on some motor speed vane pumps. The bearing uses a fluid boundary forming principle to eliminate shaft-to-bearing contact. The shaft hydroplanes above the bearing surface on a cushion of liquid. In this hydrodynamic condition, there is no metal-to-metal contact, and thus bearing life is extended indefinitely. The pump maintains optimum bearing characteristics even under a wide range of operating conditions. Reduced shaft/bearing contact minimizes friction and results in higher mechanical efficiency and energy savings.
The second notable improvement is a cavitation/noise suppression liner. Cavitation can severely impact a pump's performance and efficiency as the liquid changes to a vapor inside the pump chamber. This decreases flow through the pump and can cause substantial damage to the pump as the vapor bubbles collapse back to the liquid state. This unique invention controls the wear effects of cavitation and reduces noise levels up to 15 dbA, giving the pump an added level of protection and extended service life.
Pumping systems are a major energy consumer and a vital necessity to every plant's operation. A wealth of advice on saving energy through proper pump selection and improving pumping systems is available through the Department of Energy's Industrial Technologies Program (ITP) and through the Hydraulic Institute's Pump Systems Matter initiative (www.pumpsystemsmatter.org). The energy-saving information provided by these two institutions is easy to understand and covers both centrifugal and positive displacement pumps. The major premise supported by each institution is that in order for operations to improve energy savings significantly, they must take a systems approach, shifting the focus from the performance of individual components to that of the entire system. This approach will enable operators to improve reliability, performance, and efficiency of their overall pumping system, which in turn results in not only greater energy savings but also higher productivity and optimized performance and profitability. This means utilizing the best technology (centrifugal or positive displacement), properly sized with the appropriate piping design and control valve configurations, to ensure the highest efficiency for the application.
Although the operating principles of positive displacement and centrifugal pumps differ widely, both types can be used to serve the same applications in many cases. In these instances, certain positive displacement pumps may offer substantial opportunities in the effort to improve processes and productivity as well as maintenance and energy cost savings. Positive displacement pumps generally require less NPSHA than centrifugal pumps, and they may offer more flexibility relative to dealing with varying changes in pressure and flow requirements of continuous-type processes. Also, positive displacement pumps maintain higher efficiencies throughout the viscosity range. Therefore, in the overlap where both types of pumps can operate, a positive displacement pump's high mechanical efficiency can offer improved energy savings.
In recent years, significant design advancements have given sliding vane technology a decisive advantage over other positive displacement pump types, specifically with regards to optimized performance, low-shear capability, lowest life-cycle cost, and energy efficiency.
By design, sliding vane pumps operate with high volumetric efficiency and low slippage, allowing application at substantially lower viscosity than other positive displacement pump types. Along with benefits such as quieter operation, longer service life, and reduced maintenance requirements, sliding vane technology may also result in significantly reduced energy consumption.
Bill Bohr is the director of product management at Blackmer, Grand Rapids, MI, a leader in the design and manufacture of high-quality flow technologies including rotary vane, eccentric disc, and peristaltic hose positive displacement pumps, centrifugal pumps, screw compressors, air elimination systems, and sliding vane and reciprocating compressors for the transfer of liquid and gas products. More information is available by calling 616-241-1611 or visiting www.blackmer.com.