In an effort to reduce energy costs and carbon dioxide emissions, global industrial manufacturer and service provider SKF provides an energy monitoring service for the pumps industry to help pump operators track system efficiency by implementing energy systems optimisation.
Tracking periodic measurements of pressure, flow and power for each pump installed at a company provides the data needed for the analysis, conducted by SKF @ptitude software.
This is based on the company’s operator-driven reliability concept, providing plant operators with the information they need to identify improvement opportunities for their pump systems.
The concept can also be incorporated into any condition-monitoring programme, which SKF recommends be adapted to include the tracked data, as condition monitoring alone does not provide all the information needed to assess the health of a pump.
SKF says, for most process industries, rotodynamic pumps represent a key component of their business processes. However, many facilities take a ‘fit and forget’ approach when undertaking maintenance of these vital pieces of equipment – at least until critical repair is needed.
There can be severe cost penalties associated with this approach, including reduced productivity and higher-than-necessary energy and maintenance costs, says the company, adding that a carefully planned and implemented optimisation programme can help alleviate these unnecessary costs.
SKF maintains that improving the efficiency of a system leads to reduced energy use, thereby resulting in lower operating costs. Further, while expected energy cost savings are often used to justify a pump improvement project, the bene- fits often extend well beyond energy savings.
For example, shaft misalignment is responsible for up to 50% of all costs related to rotating machinery breakdowns. Accurately aligning shafts can prevent pump breakdowns and reduce unplanned downtime that results in a loss of production, says SKF.
The point at which the highest proportion of energy from the shaft of a pump is transferred to the fluid being pumped is the best efficiency point (BEP) of that pump. At this point, internal forces in the pump are reduced.
As the operating point of a pump moves away from the BEP, this energy transfer efficiency falls and axial and radial forces increase. Although some energy loss is inevitable – such as when friction occurs at wetted surfaces, at seal faces and within bearings – some of the energy that is not being transferred from the shaft to the fluid is wasted, says SKF.
Of this wasted energy, some is lost by internal recirculation within the pump and some as heat or vibration. These are destructive forces and, therefore, the relationship between reliability and energy efficiency is clear – as more energy is wasted, destructive forces increase in intensity, reducing reliability, adds the company.