Industrial Utility Efficiency    

Compressor Controls

Many OEMs of air compressors, dryers, sensors and master controls are integrating monitoring features and capabilities into their components. It would seem a no-brainer to keep it simple and use those sensors and systems for both control and monitoring. What could be simpler? 
The 2019 AEE World Energy Conference and Expo was held September 25-27 at the Walter E. Washington Convention Center in Washington D.C. The event featured 14+ tracks, 56 sessions, over 260 individual speakers, and 62 exhibitors.  Both Chiller & Cooling Best Practices and Compressed Air Best Practices® Magazines were pleased to be in the literature bins at the 2019 AEE World!
Maintenance is the customer of controls and energy engineering is the customer of monitoring. And I discussed potential problems that can occur when combining monitoring and control in the same system. In this article, I will get more specific about building practical systems that address both controls and monitoring.
By far the most important development in the world of screw type air compressors has been the introduction of variable speed control using electronic variable frequency drives (VFD’s). Systems that run with at least one air compressor at part load can almost always operate more efficiently if a well-controlled VFD is added to the system. But what if a system has two or more VFD units? This article discusses the challenges in controlling multiple VFD air compressors with some suggested solutions.
Baseline measurements include flow, power, pressure, production output, and other relevant variables impacting compressed air use. These data evaluate trending averages to develop Key Performance Indicator (KPI) and Energy Performance Indicator (EnPI) parameters and establish base‑year performance. The focus of this article is the application, evaluation, and analysis of baseline measurements to provide information necessary to improve Compressed Air Supply Efficiency.
All industrial facilities use some form of compressed air, and in most, the air compressors consume a significant amount of the total energy bill. A facility with a good energy management system is likely to identify their compressed air system as a significant energy user (SEU). If the facility were using an energy management standard, such as ISO 50001, they would be required to assess and track the energy consumption of all their SEU’s. In the case of the metal processing facility, they were measuring the output of more than 250 devices within the plant, including building heaters, RTU’s, dust collectors, and also tracking the consumption of their electricity, natural gas and water. 
In most industrial plants, data is everywhere. It resides in flow through pipes, pressure in tanks, vibration on rotating equipment, temperatures in heat exchangers, and electrical energy power consumption in motors. If we can acquire this data and make sense out of the patterns we can take actions to make our plants more efficient and reliable.
To address a mandate for cutting operations energy usage at facilities by 25 percent without major capital expenditures, a major manufacturing company set its sites on better control of its compressed air systems.  The project, implemented at 10 manufacturing plants over the course of three years, saves the company $977,093 annually in energy costs – and was completed with zero out-of-pocket costs.
By finding a better way to control and manage its compressed air system, North American Lighting, Paris, Ill., has reduced its total compressed air energy use by 27 percent – and in the process – saves over 1,100,000 kWh/year for a total annual savings of $91,000. The project also achieved a payback of less than one year.
A food processor in Western Canada hired an auditor to assess the energy efficiency of its compressed air system. The results revealed surprises about the operation of some important elements of the system, and detected that the air compressors were having control gap problems. Additionally, the audit led to initial energy savings of $20,000 – and identified the potential to achieve overall operational savings of 45%. The following details some of the audit findings and results.
The University of Manitoba Bannatyne Campus, Canada, upgraded its compressed air system to include variable speed drive (VSD) air compressors and the use of internal heat-of-compression (HOC) drying, replacing oil-free air compressors and refrigerated dryers that reached the end of useful life. In doing so, the campus reduced annual energy consumption by 15%, improved the quality of the compressed air to modern day instrument air standards and gained additional compressed-air capacity. The local utility also awarded the medical campus an incentive of $13,500, offsetting the cost of the initiative.