The 3 kEys
- Operate your compressed air system at the lowest possible pressure necessary to get the work done.
- Implement a leak detection and maintenance regime to reduce or eliminate what would otherwise be wasted energy consumption.
- Change filters regularly.
Optimizing System Pressure
One of the most effective strategies to reduce energy consumption in industrial compressed air systems is optimizing system pressure, as unnecessarily high pressures equate to excessive energy use. Lowering system pressure by just 2 psi can yield a 1% reduction in energy consumption, and reducing pressure from 120 psi to 100 psi can decrease energy by approximately 10%. It is important to balance the pressure requirements of various tools and equipment with the minimum pressure needed to ensure efficiency while reducing compressor workload.
Eliminate inappropriate uses of compressed air, such as open blowing or cooling. And use pressure regulators at individual workstations to control extraordinary spot pressure needs, rather than increasing system-wide pressure to handle one or two workstations.
Consider replacing your pneumatic tools as well, as compressed air, is generally inefficient due to energy losses in compression, distribution, and leakage. Electric tools convert energy directly into mechanical work, minimizing waste. Comparatively, air compressors typically operate at 10-15% efficiency due to losses in heat, friction, and leaks, while electric motors can reach efficiencies above 80%. And electric tools can be battery-powered, reducing reliance on stationary compressed air lines, improving mobility. The U.S. Department of Energy has completed a case study entitled A case study of replacing pneumatic tools with battery-powered ones at an automobile assembly plant, and it’s worth your time reading it. Quoting from its conclusion, “for the compressed air system in this study, the energy cost percentage savings for a battery powered tool was about 76%, which was due mainly to the energy efficiency difference between the battery-powered and pneumatic tools.” Two words: that’s huge.
Obviously, when you reduce the load on the system, you can reduce the pressure, which in turn reduces its energy consumption.
Leak Detection and Maintenance
Compressed air leaks are a significant source of energy waste. Implementing regular maintenance and employing leak detection systems can help mitigate these losses. Incorporating advanced monitoring technologies, such as flowmeters and sensors, can facilitate continuous monitoring and early detection of leaks, ensuring the system operates at peak efficiency.
Be sure to use ultrasonic leak detectors to pinpoint air leaks, and immediately repair or replace faulty hoses, pipes, fittings, and seals.
For an even deeper drilling into your system, utilize the U.S. Department of Energy’s Industrial Technologies program’s AIRMaster+, which provides a systematic approach for assessing the supply-side performance of compressed air systems. Using plant-specific data, the software effectively evaluates supply side operational costs for various equipment configurations and system profiles. It provides useful estimates of the potential savings to be gained from selected energy efficiency measures and calculates the associated simple payback periods. Leak detection is a part of its regime.
Regular Maintenance and Filter Changes
Regularly replacing filters helps ensure air quality and prevents pressure drops, while consistent maintenance undoubtedly reduces energy costs. Maintenance schedules can also help prevent equipment breakdowns that lead to downtime and lost production.
A clogged filter increases pressure drop, forcing the compressor to work harder, consuming more energy. A clean filter typically has a pressure drop of 1-2 psi, while a clogged filter can cause a pressure drop of 7-10 psi or more. Every 2 psi increase in pressure drop results in about a 1% increase in energy consumption. If a compressor operates at 100 kW, a clogged filter could add 3-5% more energy consumption, costing an additional $3,000–$5,000 per year (assuming an industrial electricity rate of $0.10 per kWh and 8,000 hours of operation annually). Replacing the filter represents a Simple Payback of 1-6 months, meaning the cost of replacing the filter – material + labor combined – is quickly recouped in energy savings and maintenance reduction.
Scott Galloway of Donaldson Company has written a comprehensive blog article on the importance of filter management, and you can find it here: Energy Use in Air Compressors Impacted by the Efficiency of 3 Filters. It’s as thorough as I’ve seen.
Air Storage and Piping Review
Implementing compressed air storage solutions, such as reservoirs or tanks, allows for better management of demand fluctuations and can reduce the need for continuous compressor operation. This approach not only enhances system efficiency but also contributes to a more sustainable operational model during low-demand periods.
The design and layout of the piping infrastructure plays a crucial role in energy efficiency. Increasing pipe diameter reduces pressure drops, while minimizing the distance air travels can further enhance efficiency. Strategies such as avoiding sharp bends and incorporating non-return valves are also beneficial in optimizing system performance.
Effective Compressor Management
Managing the operation of compressors is vital, and involves coordinating multiple compressors to adjust energy usage in accordance with demand fluctuations. For rotary screw compressors, it is advisable to set the pressure points so that all but one compressor is fully loaded, with the remaining compressor functioning as a trim unit.
The integration of automation and advanced control systems is essential for optimizing the performance of compressed air systems. Automated controls can dynamically adjust operations based on real-time demand, helping to minimize energy consumption.
Employing control strategies tailored to the system’s requirements, such as start/stop control or more complex orchestration of multiple compressors, ensures effective energy management.
