Optimize compressed air systems

Contributing Editor Sheila Kennedy explains how to optimize compressed air quality, moisture, energy and priorities.

By Sheila Kennedy, contributing editor

New instrumentation and controls for compressed air systems help plants with proactive monitoring and management of compressor pressure, air quality, moisture, energy consumption and operating costs. Compressed air assessments and audits are beneficial for establishing technology priorities and optimizing system performance.

Pressure: “Reducing air pressure is an easy way to reduce energy costs, leakage rates and air usage, and increase the life of the compressor,” says Bill Scales, CEO of Scales Industrial Technologies. “Most plants have opportunities to address leaks and lower their operating pressure. Generally speaking, if you drop your system pressure by 10 psi, the reduction in kW input to the compressor is about 5%. System over-pressurization results in increased compressed air consumption and often isn’t required,” says Niff Ambrosino, Scales’ general manager.

Allen-Bradley’s solid-state 836E pressure sensors are suitable for air-pressure measurement and monitoring. These compact condition-sensors have a gauge pressure range extending from -15 psi to 6,000 psi, and the indications are presented in a four-character digital display. Constructed of corrosion-resistant stainless steel with an IP66 enclosure rating and no moving parts, the 836E accommodates harsh industrial applications.

Air quality: Improving air quality reduces energy costs and extends compressor life. Beko Technologies takes an integrated approach to managing air quality by combining oil adsorption, dust filtration and residual oil measurement. The company’s Clearpoint V activated carbon adsorber has a readily connected oil-free dust filter. It adsorbs oil vapors and odor with low pressure drop. Optionally, adding Beko’s OilControl, a residual oil-measuring system, allows online, real-time monitoring of compressed-air oil content at the adsorber outlet. Alternately, an adapter with an oil-check indicator can be mounted to assess air quality.

Moisture: Moisture can contaminate equipment and products, cause rust and potentially freeze in air tools. Many compressors feature built-in dew point trending. For those that don’t, Scales recommends dew point monitors that have dry contacts to signal elevated dew points. Remote monitoring services might be available for compressors and dryers, and if action is required, a technician is dispatched from the service provider.

Automating moisture drainage improves reliability and reduces energy and maintenance costs. The Automatic Magnet Drain (AMD) 1550 from Kaeser Compressors removes captured condensate and contaminants from air systems. The lightweight drain trap is corrosion-resistant and durable and handles large amounts of liquid. The condensate chamber is isolated from the control mechanism, which avoids fouling, sticking and excessive maintenance. The AMD 1550 also maintains a “liquid seal” that prevents compressed air loss and saves energy.

Energy consumption: Fixing leaks and eliminating inappropriate uses can reduce energy consumption quickly. In some compressors, operating at partial load can waste energy. For example, a rotary screw unit operating with intake modulation control at 50% of full capacity uses 85% of full-load power and wastes 35% of the input kilowatts. Compressors with variable-speed drives or variable-displacement controls do a much better job of reducing energy consumption at part load.

To automate energy management for multiple compressor systems, Scales’ Smart Sequencer selects and runs the most efficient compressor combination to meet changing production demands. The PLC-based controller monitors and controls any number of compressors of any type, size and manufacturer, and ensures minimized power consumption.

Operating costs: Well-coordinated air systems have reduced operating and maintenance costs. EnergAir offers Metacentre, a product family that includes machine controllers, I/O modules, communication interface modules, pressure sensors, variable-speed drives and software. Suited for systems with as many as 24 compressors, Metacentre systems manage compressors and auxiliary equipment site-wide “as one” to balance equipment utilization and system pressure. EnergAir’s PC Visualisation software monitors, controls, trends and reports key performance indicators for better maintenance and reliability.

Establishing priorities: A compressed air system assessment or audit reveals opportunities for improvement. Acting on the recommendations pays dividends in energy savings, reliability and production efficiencies. “Our compressed air system experts look for inappropriate compressed air usage, waste and inefficiencies. If we can’t save you the cost of the assessment or audit through energy savings, there’ll be no fee for the expert’s time,” Scales says.

E-mail Contributing Editor Sheila Kennedy, managing director of Additive Communications, at Sheila@addcomm.com.

Reference Web sites:
www.scalesair.com
www.ab.com
www.beko.de
www.kaeser.com
www.energair.com
www.plantservices.com/articles/2008/096.html

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