MATERIALS HANDLING
requirements. Regardless of the industry, the transactional purchase and sale of pumping equipment was primarily based on the capital cost of the equipment and availability was the secondary factor, provided there was compliance with the relevant specifications. However, as processes required
increasingly higher throughputs, pump sizes became larger, and the cost of the energy needed to run them became very noticeable. As an example, pumps used for absorber recycle applications in the power industry increased in size as process flow rates went from 2,000m3
1970s to over 15,000m3
/h in the mid- /h
in the 2000s, and motor powers increased from ~250kW to 1,000kW and upwards. With the
environmental impact of industrial processes coming under intense focus on a global scale and following the Kyoto Climate Summit, some European governments introduced legislation to penalise energy usage and enforce the use of energy- efficient equipment. Furthermore, mandatory energy efficiency regulations are now being introduced in several key countries, including the MEI index in Europe and various others in China, Canada and the USA. Despite this, by 2050, worldwide energy consumption is expected to be 50% greater than it was in 2018. Pumping systems account for more than 20% of the world’s electrical energy demand, and in certain industrial plant operations, they can be responsible for between 25% and 50% of the site’s total energy usage.
Pump designs
further developed into applications
where the transported fluids contained solid particles, the wear rates of pump
components increased, and another factor started to take prominence – the cost and availability of spare parts. Te mining industry was particularly focused on this aspect as pumps were used for increasingly more arduous applications. As a result, materials technology, as well as the hydraulic design, became critical. Tis noticeable increase in the costs of energy consumption and spare parts consumption (including warehousing, inventory handling and labour) resulted in pumping equipment being treated as an asset and assessed in terms of the total cost of ownership (TCO) over a given period, such as one, three or five years. ln evaluating TCO, three main elements were identified:
initial capital cost; operating cost; labour cost. Of course, the proportions of these costs in the TCO vary depending on the applications that pumps are used for. Te figures below show the difference between an example based on a clean fluid and one based on an abrasive fluid. Although this analysis is a widely used one and covers most major elements of the costs of operating pumps, several other factors should not be overlooked.
CORRECT PUMP SELECTION A centrifugal pump’s performance characteristics include a best efficiency range, where reliability and hydraulic efficiency are at their highest. Modern pump designs can achieve very high efficiencies and selecting duty points in the best efficiency range should be a priority. Moving away from this range results not only in a loss of efficiency but also in compromised performance of bearing components and the wear life of hydraulic parts, which is particularly critical in slurry pump applications. Tis affects both energy consumption as well as useful component life. Te most common reason why pumps operate away from the best efficiency range is the miscalculation of the site and operating conditions, resulting in the pump performance and system curve not meeting at the desired duty point.
CORRECT MOTOR SELECTION Electric motors operate at optimum efficiency depending on the load at which
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RIGHT: New specifications demand innovative manufacturing techniques BELOW: Sulzer’s latest pump technology
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