The availability, performance and output of an individual machine or production line are key factors affecting operational efficiency, but these variables can be heavily impacted by breakdown or process issues. The key to maximising operational efficiency, therefore, is to ensure that production plant performance is optimised.
A key enabler to the achievement of this goal is the adoption of an appropriate maintenance and asset management strategy that will extend product life and reduce plant downtime. In particular, the optimal selection and maintenance of drive systems for process equipment such as pumps and valves, impacts positively on both operational efficiency and reduced energy consumption, both of which are key to maintaining competitiveness.
The importance of selecting the right drive or motor is brought home clearly by figures showing that, in the UK, electric motors and drives account for more than two thirds of power consumption in industry. Yet, many motors are unnecessarily oversized for the machines they drive. The annual energy consumption cost of running a motor can be up to 10 times its purchase cost. A 10kW motor operating at 87% efficiency could cost £1,500 more over its lifetime than one that’s just 5% more efficient. Meanwhile, in any application where the pump isn’t required to work constantly at full speed, energy efficiency can be further increased through the specification of a variable speed drive (VSD), which can reduce energy consumption by up to 50%.
The energy saving and process improvement benefits of VSDs are well proven across a range of manufacturing applications. VSDs can also help to increase the life of mechanical drive train components, which benefit from a smoother start-up. As well as driving pumps, in the food industry, VSDs are commonly used in applications such as on extraction fans to control oven temperatures. One typical pump application in the sector saw a pump being driven by a 21kW motor operating at 90% demand and costing £12,532 a year to run. The introduction of a VSD reduced the annual energy consumption by more than £3,000.
Given the many sources of funding available for new, energy-efficient equipment such as high efficiency motors and VSDs, as well as the rapid payback achievable, there’s often a strong business case for replacing inefficient or failing motors and drive systems.
In the UK, the Carbon Trust’s Enhanced Capital Allowance (ECA) scheme is a form of accelerated tax relief that encourages businesses to invest in energy efficient plant and machinery from its highly extensive Energy Technology List (ETL).
Companies purchasing products from this list can claim 100% first-year capital allowance on their acquisitions, effectively writing off the entire cost against taxable profits during that financial year.
In the above example, based on a VSD costing £2,000, payback can be achieved within eight months. Meanwhile, as a further incentive for small to medium enterprise (SME) manufacturers to commit to more energy efficient manufacturing processes, the Trust has doubled the maximum size of its interest-free energy efficiency loans from £100,000 to £200,000, and increased the overall annual amount available for loans by 45% to £31m. The loans are unsecured and repayable over a four-year period, and with reduced availability of alternative sources of finance, may even be available for the total cost of projects that deliver the required reduction in carbon emissions.
Other initiatives are available in countries throughout Europe, as governments become increasingly conscious of the benefit of improved energy efficiency.
Once the correct products have been selected and commissioned, an appropriate condition monitoring programme and a proactive maintenance schedule are required to ensure they’re operating at maximum efficiency.
Techniques such as thermography and vibration analysis will identify any problem areas and allow early remedial action to be taken to minimise energy usage and prevent breakdown. Precision alignment of components, for example, is proven to create energy savings of up to 5%, while properly aligned machinery is also more reliable.
A variety of laser alignment tools are available for this task from several different suppliers, including SKF, which produces laser alignment tools for shafts and belts, and other companies that make pulley alignment tools as well as geometric systems.
The importance of a rigorous lubrication and sealing regime cannot be overestimated and the actual product specified is often as important as when, and how well, it’s applied. All lubricants have a specified effective temperature range outside which they cannot be guaranteed to perform to the required standard. Using the wrong product will almost certainly impact negatively on machine performance. Similarly, incorrect application or the use of insufficient quantities of lubricant will increase friction and rolling resistance, reducing energy efficiency while increasing the risk of premature component failure. Optimising this element of the maintenance programme can reduce energy usage by up to 2%.
One particular manufacturer where investment in energy efficient products has delivered significant and measurable cost savings is Cadbury. Through its ‘Purple Goes Green’ campaign, the company has pledged to reduce its absolute carbon emissions by 50% by 2020.
In one of several projects completed with Cadbury during 2009, Brammer reduced carbon emissions by 300 tonnes while delivering a cost saving of nearly £60,000. Brammer was called in to assess the manufacturing process at the Trebor Bassett factory in Sheffield, UK. The gum stoves, part of the jelly baby process, were identified as an area where the specification of more energy efficient components would significantly reduce carbon emissions and deliver reduced energy consumption and tangible cost savings. Brammer developed a revised, more energy efficient specification and, after the new equipment was successfully trialled on four of the stoves, all 13 gum stoves were upgraded.
Brammer replaced the two 11kw motors in each stove with more efficient and equally effective 4kw motors. Meanwhile, the standard V belts were replaced with Gates Poly Chain synchronous drive belts and the motors improved their energy efficiency with the installation of a variable speed drive to each stove. This increased process speed control and improved the effectiveness of the production process.
Another project at the Sheffield factory has seen Brammer deliver significant carbon emission reductions and a further £16,000 energy cost saving. A revised, more energy efficient drive specification was developed, which consisted of an EFF1 motor linked to a VSD. The standard V belts were replaced with Gates Poly Chain synchronous drive belts. By replacing standard V belts with Gates Poly Chain belts, Brammer was able to achieve an energy saving of between 5-6%.
This instant payback, combined with the improved results from the variable speed drive and EFF1 motor, gave Cadbury immediate, quantifiable energy savings amounting to 185,000kwh (or 79 tonnes of CO2 each year), a further example of how reviewing processes and optimising product specification can enhance both operations and energy efficiency.
Whether a company’s focus is on short-term cost savings or on positioning the company for the long-term, investment in new, more energy efficient, equipment and correct management of those assets will help to reduce costs, increase production uptime and productivity and enhance business competitiveness.
Jeremy Salisbury is head of marketing for Brammer, a division of the European distributor of industrial, maintenance, repair and overhaul products and services.
© FoodBev Media Ltd 2020
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