Compressed air systems are part of most industrial facilities and could be described as the “heart of the plant.” Should the system fail to deliver a reliable, clean, cool, and dry supply of compressed air at a constant pressure, in a cost-effective manner, some big troubles may occur.
In years past, ensuring this constant delivery required continuous manual intervention that consumed valuable time resources from your stretched maintenance personnel. But things are different these days. In the last ten years or so, both large innovations and incremental changes in the compressed air world have improved things for compressed air users.
This article reviews key improvements that have happened in the compressed air industry over the last 10 years in the areas of technology design, asset management, and industry-wide performance metrics and training opportunities.
1. Technology design
Variable speed drive (VSD) compressors
Industrial air compressors that are controlled by variable frequency drives and DC drives have been around since the late 1990s; however, the past 10 years have seen significant improvements implemented.
VSD compressors adjust their motor speed to match the exact air demand of a system while providing a constant pressure. This type of control is one of the most efficient methods of part-loading compressors and results in significant energy savings by reducing the power consumed during low demand periods in an almost 1:1 turndown ratio. The technology also extends the lifespan of mechanical components by reducing mechanical stress and wear, leading to lower maintenance costs and increased reliability.
In the early days of VSD technology the control enhancement was nothing more than bolting on a variable drive on a standard compressor. This resulted in less than optimum performance and limited speed turndown, causing motor failures, control problems, and reduced efficiency, especially at the low end of the speed range. In recent times the manufacturers have learned how to match the characteristics of the air ends with the required speed range performances, providing a flatter efficiency curve, increased turndown, and better efficiency.
Manufacturers have started providing better quality drives with the compressors as well as specially designed motors that are more compatible with VSD technology, thereby extending the lifespan of the units. We all have learned that a “control gap” exists in systems where the VSD is not correctly sized. In the old days a customer might purchase three equal sized 100 horsepower compressors for their system, one being VSD, but through experience this turned out to be a problem. To prevent control gap we have learned the VSD must be larger than the base compressors with which they must work. This often requires that the VSD be at least one size larger than the fixed speed compressors.
Finally, in recent years the specific power numbers of all compressors have been coming down (low is good), including VSD versions, and currently VSD controls are starting to creep into the market for centrifugal compressors.
Noise abatement
Several innovations have been implemented in recent years to make industrial air compressors quieter. Some compressor designs are so quiet it could be argued that there is no longer a need for a separate compressor room in clean locations.
One of the primary methods for reducing noise in industrial air compressors is the use of sound insulation and specialized enclosures. These enclosures are now designed with better sound-absorbing materials that significantly dampen the noise generated by the compressor's motor and internal components. They often feature advanced designs that not only contain noise but also allow for improved ventilation to prevent overheating.
Innovations in vibration dampening have been implemented through the use of rubber mounts, pads, and other isolators that absorb vibrations and prevent them from being transmitted to the surrounding structure. Also, manufacturers have developed smoother-operating motors and fans with improved aerodynamic designs and quieter bearings, and these advancements are helping to reduce noise associated with air cooling systems.
Lastly, the use of advanced materials and construction techniques has further helped reduce noise levels. Components made from composite materials can absorb sound more effectively than traditional metal parts. These materials are used in various parts of the compressor, including housings and guards, to reduce noise emission.
Heat recovery
Industrial air compressor heat recovery systems have become more plentiful and are now easily integrated, resulting in significantly enhanced energy efficiency and sustainability in various industrial processes or plant heating requirements that can use the heat-of-compression generated by air compressors.
Traditionally, waste compressor heat is expelled to the atmosphere, resulting in energy losses. However, advanced heat recovery technologies now allow this heat to be effectively harnessed and utilized for other purposes within the facility, such as space heating, water heating, or preheating air for other industrial processes. By integrating heat exchangers and efficient heat transfer mechanisms, these systems can reclaim up to 90% of the waste heat, turning a potential energy loss into a valuable resource.
Also by capturing waste heat, companies can lower their dependence on additional heating sources, thereby reducing fuel consumption and greenhouse gas emissions. Overall, these advancements in heat recovery technology are playing an important role in promoting energy conservation and sustainability in the industrial sector.
2. Asset management
System monitoring
In earlier days, compressed air monitoring systems consisted of various analog gauges installed on the compressor and various other locations. It was rare to see any type of flow measurement and even rarer to see power consumption monitoring installed. Personnel maintaining these systems needed to rely on paper-based methods to trend and troubleshoot their systems in order to detect inefficiency and impending equipment failures.
Modern control and monitoring systems now feature intuitive, user-friendly interfaces that make it easier for operators to understand and manage system performance. These interfaces often include visual dashboards, customizable reports, and simple navigation. Many manufacturers now choose to transmit data through onboard cellular connections, storing the data for analysis. This data can be used in tending and troubleshooting the system and generating warnings or alarms.
Many modern compressed air systems now use advanced smart controllers that optimize compressor performance by adjusting operations based on real-time demand. These controllers help reduce energy consumption and extend the lifespan of the compressor. In particular, the integration of Internet of Things (IoT) technology allows for real-time monitoring and remote control of compressed air systems. IoT-enabled devices can be used to collect and analyze data continuously, providing insights into system performance and potential issues. These systems can monitor and manage the energy usage of compressed air systems, identifying inefficiencies and suggesting improvements.
There also has been a move to cloud-based platforms for storing and analyzing the data used to monitor compressed air systems, providing centralized access to these data from multiple locations. Users can access performance data, generate reports, and receive alerts from anywhere, enhancing overall system management. Some of these systems have integrated digital twin technology, a way to create a virtual replica of the compressed air system, allowing for detailed simulation and what-if analysis to be used in improving the system operation. This helps in diagnosing problems, optimizing performance, and planning upgrades without interrupting the actual system.
One nagging problem challenging good compressor control is the lack of a universal agreed-upon air compressor communication protocol, unlike the HVAC industry (which does rely on a common protocol). The root of this challenge centers on the fact that compressors of different makes and vintages persist in the field, and they continue to leverage a variety of available electronic communication languages. Control designers have now started to design their systems with the ability to strip any operating data and even to control the equipment through digital connections.
Air quality monitoring
As the market for higher quality compressed air has grown so has the availability of new, more accurate, and more affordable instruments to detect the dryness and cleanliness of produced compressed air. Many facilities in the food and electronics industries must ensure that compressed air is free from contamination that could cause product rejection. Some must actually report and validate their air quality to inspection agencies.
Instrumentation has greatly improved for the measurement of dew point, temperature, flow, and oil content. Recently some companies have developed sophisticated measurement boxes that can even count and categorize entrained particles within the compressed air that could harm sensitive processes. Use of these instruments protects the compressed air production process against hidden failures that may result in future product quality problems.
Ultrasonic leak detection
There have been some big changes in the ultrasonic leak detection world. Recently developed acoustical imaging leak detectors represent a significant advancement in the detection and quantification of air leaks. These devices employ arrays of sensitive microphones and advanced software to detect the ultrasonic sound waves generated by air leaks.
The collected data is then processed to create a visual representation, or acoustic image, of the sound environment on a display screen. This visual image highlights the precise location of leaks, making it easier for maintenance personnel to identify and address them quickly and accurately, and in many cases will provide an estimate of the cost. The technology's ability to provide real-time, high-resolution images enables more time efficient and accurate inspections compared to traditional methods, such as using standard ultrasonic guns.
3. Industry Initiatives
CAGI Data Sheets and third-party verification
The Compressed Air and Gas Institute (CAGI) 3rd Party Performance Verification Program is undoubtedly an important industry development from the past 10 years. The program has been running for several years now, and was started to ensure the accuracy and reliability of performance claims made by manufacturers of compressed air equipment. In this program, participating manufacturers voluntarily submit their products for testing by independent, accredited laboratories. These labs measure key performance metrics such as airflow, power consumption, and efficiency, and then compare the results against the manufacturer's claims. Verified data is published in standardized CAGI Data Sheets, providing a transparent and consistent format for consumers. Standardized data sheets are required to be published on company’s websites, allowing easy comparison of different products and ensuring that consumers can select the most efficient and suitable equipment for their needs.
Recently added to CAGI data sheets is a performance indicator called Isentropic Efficiency. This metric eliminates the confusion about published Specific Power (kilowatts per 100 cfm) numbers, which change with compressor output pressure, and provides a more accurate and comprehensive assessment of a compressor's energy efficiency as compared to traditional metrics. By including Isentropic Efficiency, CAGI Data Sheets now offer a clearer picture of how well a compressor performs under real-world conditions, through all desired operating pressures, enabling consumers to make more informed decisions based on true energy performance.
CAGI data sheets have been developed for fixed speed, variable displacement, and variable speed screw compressors in both lubricated and non-lubricated varieties. There are also CAGI sheets for refrigerated air dryers, designed to aid compressed air users in comparing the difference between inefficient standard dryers using hot gas bypass control and efficient cycling dryers that might use thermal mass control, or some other method to save energy during part loads.
Training and certification
There also have been some key changes to training and certification programs within the compressed air industry over the past 10 years. Comprehensive training programs have been offered by the Compressed Air Challenge since the late 1990s, focusing on best practices for compressed air system design, operation, and maintenance. These programs have educated tens of thousands of industry professionals on how to optimize system efficiency, reduce energy consumption, and improve reliability.
Within the last ten years the most popular delivery method for these sessions has become virtual rather than in-person, a trend accelerated during the COVID crisis and one that has greatly decreased the cost for both participants and training hosts. The CAC’s Fundamentals and Advanced training continue to be updated to meet with modern day standards. A new training has been developed called Compressed Air Assessment and Project Development to teach industrial compressed air professionals about best practices in assessment methods. This training is part of the body of knowledge used in two newly developed CAGI personnel certification programs.
The CAGI CCASS (Certified Compressed Air System Specialist) program recognizes individuals who have demonstrated a high level of expertise in compressed air systems. This certification ensures that professionals have the knowledge and skills to design, operate, and maintain efficient and reliable compressed air systems, promoting industry standards and best practices.
Lastly, an upcoming CCASA (Certified Compressed Air System Auditor) program certifies auditors who specialize in assessing compressed air systems and identifying opportunities for improvement. Certified auditors conduct thorough evaluations, provide actionable recommendations, and help facilities implement energy-saving measures. This certification enhances the credibility and effectiveness of compressed air system audits. Both certifications are available to anyone worldwide and are achieved by writing examinations at certified testing centers. More information on both certifications can be found at cagi.org.
Future innovations
The compressed air world continues to change and will continue to improve in the future. There are exciting developments coming to help you, the user, better operate your systems through advanced instrumentation and easy to use interfaces. Air compressors, dryers, filters, piping and other components will improve as time goes on, making air systems run more reliably and efficiently. What innovations are in store for us in the next 10 years? Let’s just wait and see.