Combining energy efficiency with productivity improvements
Most industries face the common challenges of reducing energy use whilst maintaining product quality and productivity. Productivity improvements drive up profits to satisfy stakeholders. On an industrial site with an electricity bill of £150,000 a year, about £100,000 may go on running motors.
According to ABB Drives, the energy-saving benefits of energy-saving drives are well documented. Less so are the improvements made to productivity. Meanwhile, energy prices are becoming much more volatile, a reflection of the uncertainties in the supply conditions.
Governments are also imposing legislation to force the industry to reduce energy use and greenhouse gas emissions. The UK government, for instance, has introduced the Carbon Reduction Commitment (CRC, 2008 and 2014), the Climate Change Levy (CCL, 2001) and the Energy Savings Opportunities Scheme (ESOS) which requires large users to carry out an energy audit on their plant every four years.
The impact of motor-driven applications
Improved energy efficiency and productivity do not happen overnight but are the result of a determined effort over time. A good place to start is to look at your motor-driven applications. By selecting specific applications and monitoring their performance within the process, a clear picture will emerge of where savings and improvements are achievable. This avoids wasting energy by controlling already efficient components. Variable-speed drives (VSDs) can achieve a perfect balance between the lowest energy usage and best productivity.
Energy efficiency improvements
In many processes, making changes to production volumes is done by adjusting mechanical devices like opening or closing throttle valves, dampers and/or inlet guide vanes. While these mechanical devices allow the control of system flow, they are inefficient due to the waste of energy across the restriction. Further wastage occurs when control of these devices is manual and not adjusting them in response to changes in system demand.
With VSDs, changing the motor speed achieves a change to the production volume. The automatic matching of machine speed to production requirements saves energy, particularly in pump and fan applications. Importantly, because the changes happen automatically in response to calls from the machine, the system is self-optimising.
– Less energy wastage
– Reduced electricity costs
– Lower CO2 emissions
– Matched motors and drives with lower wear and tear
Failure to put in place energy efficiency projects is sometimes due to concerns about interrupting or altering the process. However, as well as saving energy, the process can also enjoy the installation of VSDs. When making changes to the plant it is important to do it with the future in mind.
Changing constant-speed equipment to provide higher production volumes requires money and time. It may need investing in gearboxes or new belt systems as well as interrupting production to install these devices. With a VSD, speed increases of 5 to 20 per cent are available without changing the mechanics. The accurate speed control obtained with VSDs results in process optimisation.
– Enhanced end-product quality
– Increased production throughput
– Lower switchgear and cabling costs
– Maximised process up-time
– Minimised maintenance
– Reduced wastage
– Accurate processing of materials
Finally, it is important to remember that energy savings continue repaying the investment year after year.
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