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FEATURE HYDRAULICS & PNEUMATICS
ENERGY EFFICIENT COMPRESSED AIR
Niccolò Casini, product manager ELGi Compressors Europe, examines ways to consume less energy, produce more, and bring lasting benefits in terms of sustainability, profitability and effectiveness to compressed air applications
E
nergy accounts for the majority of utility costs in industry. In manufacturing processes that use compressed air, air
compressors consume approximately 12% of the total electrical energy. Over the lifespan of an air compressor, 80% of the cost is energy use, and 20% is the cost of the unit including maintenance. The revised EU Energy Efficiency Directive (EU) 2023/1791, published in September 2023, will accelerate energy efficiency across the European Union, requiring EU countries to collectively reduce their energy consumption by 11.7% by 2030, relative to the 2020 reference scenario. Additionally, EU countries will have to achieve new annual savings of on average 1.49% of total energy consumption from 2024 to 2030. Embracing energy efficiency practices is much more than compliance, it’s also the right thing to do. Decarbonisation of heavy industrial processes is central to reaching targets combatting climate change. With the industry being the third-largest carbon contributor after energy production and transport, energy efficiency measures in industrial processes have enormous decarbonisation potential.
PARTNERS Whether you’re considering a new air compressor or planning to upgrade the existing system, working closely with an expert that can design or redesign your compressed air systems, one that could then remain as your service provider, is critical. This will ensure you get the true picture of all areas that need to be addressed when aiming at improving the energy efficiency of your operations. Your expert partner would conduct a
compressed air system energy audit, or Air Audit, to identify areas of loss or inefficiencies within a compressed air system. Moreover,
50 DESIGN SOLUTIONS MARCH 2024
skilled energy audit engineers can then identify and modify faults and disorders. A complete analysis looks at everything from
the compressor to the environment in which it operates, as well as operational demands such as peaks and troughs in air demand and operational expansion planning. A finite analysis of the bigger picture – understanding how even the most minor system elements impact the energy consumption associated with the compressor. The aim is to strike the right balance in
technical and economic choices – in compressor units, capacities, operational parameters, energy efficiency, planning for future air demand changes, and considering all energy costs. An Audit Report details recommendations on short-, medium-, and long-term measures for energy conservation, along with financial estimates and analysis for their implementation. These recommendations come with databases and fact sheets generated by measurements and tests conducted in your plant and the field. After this study, manufacturers can propose making educated decisions about their assets, upgrade investments, and ultimately achieve a reduced compressed air energy consumption.
SELECTING THE RIGHT COMPRESSOR TECHNOLOGY With so many air compressor technologies available, making the right selection can be overwhelming. When choosing an air compressor, assessing the load type is critical. For example, a screw air compressor doesn't shut down immediately and goes into unload state to limit too many motor starts and stops. This unloading process consumes up to 30% of energy, increasing the company’s operating costs. When selecting the unit for
your facility, duty cycle, operating pressure, and airflow demand should be some of the key considerations. Different industries like pharmaceuticals,
automotive, food and beverage, etc. are powered by various pneumatic applications that demand a specific airflow (m3
/min).
Selecting a suitable compressed air system is crucial to ensure that the air compressor meets the airflow and pressure demands of the pneumatic applications while ensuring optimal performance and energy consumption. The duty cycle, referring to the operation
cycle or the time the compressor runs to provide compressed air at a consistent pressure and specific flow rate, is one of the critical parameters that help decide if a fixed speed drive or a variable frequency drive (VFD) is required. Manufacturers can choose from a wide range of air compressors equipped with or without a VFD based on the variation in airflow demand. In the case of a fixed-speed air compressor,
the compressor runs at the same rate, consuming the fixed power for the air demand. The electrical motor runs at the maximum constant speed irrespective of the compressed air requirement. On the other hand, the air compressor with variable frequency drive can automatically adjust the speed between its minimum and maximum range, ensuring that the compressed air generation matches the compressed air demand and subsequently consumes significantly less energy at low demand. The VFD air compressor greatly benefits industries and applications with largely varying airflow demands. However, it’s not a given that a VFD compressor is the better technology in all cases. It’s important to look at the size of the air receiver that provides a certain buffer capacity. This air receiver will ultimately handle smaller
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