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Pumping towards better control

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Features, Operations - Features

Key drivers that will lead to increase in demand for pumps and pumping solutions | Pumps are an integral part of any process and the manufacturing industry. From dosing chemicals in water treatment plants tohigh capacity pumps for sludge transfer in effluent treatment plants, it can be seen in different forms across the industry. The Freedonia 2011 study pegs the global pump demand to rise 6.4% annually to reach $76.1 billion by 2016.

Demand would be led from developing countries like China and India who continue to invest heavily in water infrastructure and electricity generation. They would be the primary drivers of this growth followed by other developing countries which continue to industrialise rapidly.

Though the Indian economy has slowed from a high of 8% towards the end of the last decade, the forecasts predict that over the long term higher capital investment needed to plug the infrastructure deficit will continue to drive the GDP growth in India, which in turn will drive the demand for pumps and pumping solutions in the country.

One challenge for India as it continues its journey from a developing country to a developed one is the rising need for energy. According to statistics, India’s energy consumption was 772,603GWh in 2011-12. Energy conservation has emerged as one of the major issues in recent years in India. Due to the huge investments required in new electricity generating plants, conservation and efficient utilisation of energy resources play a vital role in narrowing the gap between demand and supply of energy in the short term.

Pumping systems account for nearly 20% of the world’s electrical energy consumption according to a joint study by Hydraulic Institute, Europump. In some industrial plant operations they would account for 25-50% of the energy use. Needless to say improving energy efficiency of pumping systems is one of the most desirable options for bridging the energy gap for India in the short term.

The efforts to minimise this energy consumption is being led by efficient design of piping system. Design would involve selection of the right pump and piping system. Even modest viscosities dramatically affect the flow rate and efficiency of pumps. For example, while many centrifugal pumps are recommended for viscosities of 1000 cst and higher, positive displacement pumps are clearly the better choice when considering the high costs resulting from this lost efficiency.

Right-sizing of the pump enables the pump to be operated in its best efficiency range. Energy savings of up to 20% are possible when pumps are sized on reasonable system heads and capacity requirements. Using the right piping size also has a dramatic effect on the efficiency of the system. Piping system designers, today, are increasingly using sophisticated design tools to minimise the piping losses creating more and more efficient systems. Using two or more smaller pumps instead of one large pump so that excess capacity can be turned off would also help in conserving energy. Another trend increasingly visible across the industry is the increased use of controls for monitoring and improving performance of the system. As plants become increasingly automated with centralised controls more and more users are now demanding that pump controls be integrated with their process controls.

Use of variable frequency drives (VFD) which changes the speed of the motor in response to changing discharge pressure conditions is one such example. Studies on centrifugal pumps show very little efficiency change when operated at lower speeds since usually the process downstream of the pump requires less pressure at lower flow rate. So the centrifugal pump stays at a good operation point and works most efficiently. In case of diaphragm pumps, solenoid controls are used to achieve the same level of controls. Electronic pulses are used to increase or decrease the frequency of strokes and are able to control the flow rates.

Flow-meters, pH controllers and other measuring instruments provide the feedback and these parameters are then used for process control. Level switches – float type or optical non-contact type provide an input to start/stop the pump. Other types of controls consist of the ones designed to ensure longevity of the system. Surge protectors, pulsation dampeners ensure minimal damage to the piping systems due to surges. Manufacturers are now offering customised controllers “out of the box” which can be used as stand-alone controllers as well as be integrated with plant controls.

While design and control will ensure optimum selection of the equipment, one cannot neglect the importance of regular performance checks or audits. Quality audits as per ISO 9000 have brought a change in the ways audits are viewed traditionally. These audits now focus their attention on whether the system which is being installed is adequate for the given parameters.

In addition, compliance and surveillance audits are carried out to find “non conformities” and ensure that remedial actions are taken immediately to close out these points. A healthy audit process ensures optimum performance of the pumping system and ensures that the system is safe and energy efficient. Energy audits have now become an annual feature with many energy conscious users to find out opportunities to further reduce energy costs.

All the above steps will contribute to significant energy savings for the process plant owner. The pump suppliers too are doing their bit to ensure this movement towards better energy efficiency and safety. Pump selector guides or software is now becoming a standard feature on most supplier websites. Manufacturers have also tied up with third-party software vendors to enable pump users to select pumps online based on their application.

More and more pump users are now basing their purchasing decisions on Life Cycle Cost (LCC). LCC of any equipment is the total ‘lifetime’ cost to purchase, install, operate, maintain and dispose off that equipment. When used as a comparison tool between possible design or overhaul alternatives, the LCC process will show the most cost effective solution within the limits of the available data.

Thus, a smaller pipe size selection may reduce the initial cost of the system but the resultant higher heads would require a higher motor size and thus increase the running cost of the pump. If Lobe pumps are suitable for pumping liquids with some solid content, then Vane pumps are better suited to handling abrasives.

The recent M&A trend too points out to companies focusing themselves on providing complete pumping solutions to their customers instead of focusing only on a single pump technology. Thus, you would find a typical process unit having many different pumps which have been selected based on their suitability for the application.

Going forward, the focus is now on long term efficient and sustainable solutions and we see pump manufacturers responding to the challenge with complete end to end solutions – From selection of the right equipment to ensuring that the equipment gives the right performance over its complete lifetime.

Neeraj Naik

Marketing Leader, fluid management

Ingersoll Rand Industrial Technology & Services

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