Industrial Utility Efficiency

Automating Energy Efficiency in Compressed Air System Sub-Zones


Improving the Energy Intensity KPI

The objective of a compressed air management system is to improve the Key Performance Indicator (KPI) of “Energy Intensity” as it relates to compressed air. This translates into improving the ratio between the volume of product shipped and the net electricity (kWh) consumed by the compressed air system. How many thousand bottles, per compressed air kWh consumed, were shipped this month?

Compressed air management systems automate the continuous measurement and fulfillment of the appropriate volume, pressure, and quality of compressed air for each unique sub-zone in a compressed air system.

 

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Energy Efficiency Awaits in the Sub-Zones of a Compressed Air System

The opportunities for energy savings often come from moving away from the traditional “one system for the whole plant” approach. Dusty Smith, P.E., (Director of Engineering, Pneu-Logic) commented, “Energy efficiency gains are unlocked when we find ways to optimally manage each sub-zone of a compressed air system.” Compressed air management systems, like the Pneu-Logic PL4000, are designed to allow for the on-going measurement and optimal fulfillment of the appropriate volume, pressure, and quality of compressed air for each unique sub-zone in a compressed air system.

Compressed air systems assessments, focusing on the demand-side of the system, normally identify many different sub-zones with unique compressed air needs and requirements. Providing data that is normally not available to management, the system assessment will measure compressed air pressure, flow, and dew point, out on the factory floor where the machinery and processes are that use compressed air. This is a learning process where engineers discover the different sub-zones in their compressed air system – the sub-zones where the energy efficiency opportunities are waiting!

A compressed air management system, like the Pneu-Logic PL4000, provides the ability to monitor and manage unlimited inputs from the compressed air system – permanently. The data inputs, from each sub-zone, turn the PL4000 into a powerful monitoring and trending system capable of providing management with the metrics they can manage. According to Eric Bessey, P.E., (Chief Project Engineer, Pneu-Logic), “Our technology differentiates itself with its ability to absorb data from a multitude of factory floor and compressor room inputs provided from sensors we install (typically flow, temperature, pressure, dewpoint, and kW). Our control algorithms are able to take this data and continuously direct the most energy efficient way to supply the demand for compressed air in all sub-zones of the system.”

 

Compressed Air Pressure Sub-Zones

System assessments often identify processes requiring different compressed air pressures. Identifying these “sub-zones” and providing each with the appropriate pressure provide some of the biggest gains in energy efficiency. Dusty Smith, P.E., (Director of Engineering, Pneu-Logic) commented, “In plastic blow molding processes, the facility will use compressed air at both 600psig and 100 psig. These two systems typically have a crossover point wherein 600 psig air can be expanded down to 100 psig air to augment low pressure air supply. Significant improvements in energy intensity metrics are realized by optimizing the interaction between these two compressed air pressure sub-zones: one managed sub-zone for blow molding at 600-725 psi and another subzone at 100 psi for plant air functions.”

“Another typical application is when systems are split between 30-40 psi air and 90-110 psi compressed air”, continued Mr. Smith. “Food preparation plants are identifying energy-saving opportunities by supplying blow-off applications with lower pressure air supplied by blowers.” Managing these two sub-groups of a system is made possible by the Pneu-Logic PL4000 compressed air system management technology.

 

Stabilizing Air Pressure by Monitoring Signals from Storage Sub-Zones

Unstable compressed air pressure will reduce production output in a plant. It’s like having an intermittent supply of electricity. To help stabilize plant pressure, compressed air storage and demand controllers are common recommendations coming from compressed air system assessments.

The PL4000 will take the inputs from pressure sensors at the storage tank(s) and flow and pressure inputs from the demand controller. The control algorithms can take this data from both sub-zones and select the optimum mix of air compressors to run.

If multiple compressor rooms are supplying air to the storage tanks, the Pneu-Logic PL4000 is able to centralize and coordinate the control of these air compressors located in different parts of the plant.

 

Eliminate Air Leaks by Shutting-Off Compressed Air Flow to Production Sub-Zones

Most industrial facilities have areas, supplied by compressed air, which do not run 24 hours a day, 7 days a week, all year-long. These areas however, due to compressed air leaks in the piping, normally consume compressed air 8,736 hours per year. Corey Farrens described the scenario, “A metal stamping plant we worked with has many different production lines. They wanted to shut-off compressed air supply to these lines when they weren’t in production in order to save energy.” The plant installed flow meters and electro-pneumatic gate valves (in each sub-zone) able to provide signals to the Pneu-Logic PL4000 on when to supply compressed air and when to open and shut the valves.”

Managing and measuring compressed air flow heading out to different sub-zones is considered by many as, “the next frontier”, in optimizing compressed air systems. Many factories now understand their total compressed air costs because they are monitoring kW demand of their air compressors. The next step is to implement on-going measurement and management of compressed air flow heading to different sub-zones in the facility. In this way, different sub-zones can be accurately assigned kW costs that correspond to their production processes and thereby accurately manage their energy intensity.

 

Critical Use Sub-Zone: Compressed Air Used for Breathing Air

There are some applications, for compressed air, where lives literally depend upon safe supply of breathable compressed air. Mr. Smith described one such scenario “An enormous mine had stationary electric air compressors supplying compressed air to many, many zones. They experienced periodic power disruptions and wanted an automatic way to switch their breathing air supply over to the back-up diesel-powered air compressors.” Along with managing the efficient supply of compressed air for the entire mine, the centralized PL4000 was able to provide this automated solution as an identified sub-zone.

Manufacturing facilities also use high quality compressed air in sandblasting and painting applications. Dew point and CO2 monitors are installed and can send alarm signals to the PL4000. The PL4000 will use this data to warn and ultimately shut-off the air supply and even the air compressors as a safety protection to personnel and manufactured product.

 

Air Quality Sub-Zones: Reducing Production Spoilage Rates

A fast way to reduce a plant’s performance, with the energy intensity KPI, is to have product spoilage rates go up due to the presence of moisture and oil in the compressed air system. Direct-contact environments with food, delicate semiconductor chips, and surface painting processes have zero tolerance for specification deviations on pressure dew point, oil and particulate filtration. “Customers often ask us to measure, monitor, and manage air quality in critical process areas of their facility”, said Mr. Bessey. “Dewpoint measurement devices are installed downstream and our management system provides visibility to engineering.” “We also monitor differential pressure on the filtration products to ensure that the elements are changed in a timely manner to ensure that oil and particulate filtration specifications are met.”

Some facilities operate separate oil-free and oil-flooded air compressed air systems. Many plants have both types of air compressors. Compressed air system management, with the PL4000, allows both air compressor systems to be controlled simultaneously.

Energy efficiency is also discovered when creating sub-zones for compressed air quality requirements. “It’s common to see one dew point specification for a whole facility, based upon the highest air quality required in the plant – even if it’s only 20% of the total air volume, “ said Corey Farrens (Director of Sales, Pneu-Logic), “Our system assessments often recommend the installation of lower energy-cost refrigerated dryers for the portion of the factory that requires a +38 F dew point”. The PL4000 compressed air system management product will monitor dew point to ensure that each sub-zone of the facility receives the quality of air it requires.

 

Cost-Effective, Open-Architecture, Non-Proprietary, and Configurable Technology

The PL4000 high-tech compressed air system management has matured over the past few years. Mr. Smith commented, “Communication flexibility is important. Our technology works extremely well with all protocols like Rockwell Automation’s EthernetIP, and also with Modbus, CAN, and DeviceNet protocols Our engineers are also experienced in the details of how to write custom drivers for specialized IO scanners or to implement protocol bridges to get the myriad of air compressor controllers on the market, to communicate inwardly to the PL4000.”

The PL4000 SCADA server is ready for outward client connection and individual plants are given the “invisible codes”, memory map and configuration files (as requested) to configure the system to the needs of their plant. There are also no technology licensing fees.

Innovation has also brought down the average selling price of the technology. Mr. Farrens said, “We can now customize the product to meet the needs of any customer. Solution prices can start at as little as \$4,500. An innovative new payment option is also available. It allows customers to pay solely based upon realized energy savings. Pneu-Logic will provide a free system assessment and the installed PL4000 compressed air system management technology.

 

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Conclusion

Compressed air management systems automate the continuous measurement and fulfillment of the appropriate volume, pressure, and quality of compressed air for each unique sub-zone in a compressed air system. They are a critical resource allowing facilities to improve the energy intensity KPI of their compressed air systems.

 

For more information please visit www.pneulogic.com.