New-generation compressors focus on efficiency, sustainability

Atlas Copco’s E-air portable compressors are powered by lithium-ion batteries and energy-efficient electric motors.

The latest air compressors hitting the market benefit from variable-speed drives, oil-free operation and IoT capabilities.

Ken Korane • Contributing Editor

Compressed-air was a key fluid powertechnology on display at this month’s Hannover andbauma trade fairs in Germany. Between the twoshows, scores of exhibitors displayed hundreds ofnew and upgraded products.

One area of emphasis centered on sustainability, including compressors with integrated variablespeed drives that yield higher efficiency and significant energy savings, oil-free units that generate “clean” compressed air and, for mobileequipment markets, electrification.

That dovetails with a focus on designs with more-sophisticated controls to take advantage of IoT and Industry 4.0 capabilities. Such systems can continuously optimize production processes and ensure smarter use of equipment, again resulting in higher energy efficiency. And with remote monitoring capabilities, the systems can reliably predict faults and failures as part of proactive maintenance programs.

Sticker price seemed not to be the overriding concern. Users of industrial compressed-air equipment are increasingly aware that the purchase price of a compressor accounts for, on average, less than one-third of the total lifecycle cost. Energy costs make up most of the rest. That’s why the latest innovations in compressed-air technology can reduce operating expense by a sizeable margin. Here are several examples.

Kaeser Compressor’s new Sigma Smart Air system combines remote diagnostics and predictive maintenance with highly efficient air delivery.

Mobile electric power

One important challenge for the industry is finding energy-efficient solutions that cut back on CO 2 emissions and provide alternatives to fossil fuels as an energy source. Atlas Copco, Stockholm, Sweden, unveiled its latest generation of clean compressors at bauma 2019 — new sustainable mobile air equipment powered by lithium-ion batteries and energy-efficient electric motors.

Atlas Copco’s range of “clean-drive” E-air electric-powered portable compressors offers an alternative to diesel-driven units in urban construction areas. They eliminate the need for refueling, raise efficiency and lower noise levels on a working site. In areas where electric or battery-powered units are impractical, such as in remote locations without access to the grid, alternative versions integrate advanced fixed- and variable-speed drives with Stage V compliant diesel engines.

In addition, Atlas Copco planned to showcase the new IP67-rated Smart Air Xc4004 compressor controller on all its large and specialty air compressors with flows from 20 to 128 m 3 /min (700 to 4,500 cfm) and pressures up to 345 bar (5,000 psi). According to company officials, the advanced controller increases operating effectiveness and features an intuitive, easy-to-use interface.

The unit supports a new AirXpert 2.0 pneumatic regulation system and is said to significantly increase system efficiency. The Xc4004 controller lets operators manage functions like eco-mode, dynamic flow boost, multi-pressure/flow settings and emergency stop, and can boost fuel efficiency through auto load/unload and start/stop capabilities. A 7-inch display allows a simultaneous view of several parameters, including pressure and flow. Additionally, topstructured alarm settings monitor and protect the equipment.

The Xc4004 controller’s auto-diagnostic function constantly checks key areas such as engine conditions and spots potential faults, to actively increase uptime. Operators can monitor no less than 15 key parameters. Quick access to historical trends lets users perform operational analysis and assist with scheduling preventive maintenance, and as a result improves uptime and efficiency, protects the investment and drastically decreases operating costs.

A secondary point-of-use controller unit is also available and gives users the option to remotely operate their portable compressors via hard-wired or RRC radio connections, for instance in drill-rig applications.

The Smart Air Xc4004 compressor controller from Atlas Copco has auto-diagnostic capabilities and can monitor no less than 15 key parameters.

Smart air

Kaeser Compressors, Coburg, Germany, displayed the entire scope of its compressed-air products and systems at Hannover. That ranged from energy-saving rotary-screw compressors equipped with synchronous reluctance motors to portable units with variable-speed drives. But the overriding theme was the combination of highly efficient units that deliver flow on demand that were coupled with “intelligent” engineering systems.

The company’s new Sigma Smart Air technology demonstrated that compressed-air systems can operate in the age of Industry 4.0. Sigma Smart Air offers a combination of remote diagnostics and databased, predictive maintenance while ensuring efficient air delivery.

In traditional compressed-air systems, maintenance is either reactive or performed at established intervals, said company officials. In that case, there is always the risk that service will be performed too early or too late — both of which can be costly. In the Sigma Smart Air concept, real-time operating and energy data — such as discharge temperature, pressure dew point and differential pressures — for the compressed-air station are networked to and controlled by the Sigma Air Manager 4.0 master controller.

The Sigma Air Manager 4.0 handles tasks such as variable adjustment of compressed-air generation through continuous realtime monitoring and optimization. The system analyzes all operating data on an ongoing basis, simulates alternative actions and calculates the perfect compressor combinations which, according to Kaeser, results in unprecedented energy efficiency.

It also ensures maximum availability through remote diagnostics, predictive maintenance and avoidance of critical conditions. Users can monitor the operating health of a compressed air station anytime, from anywhere. This means potential faults can be detected in advance and appropriate maintenance measures automatically initiated. Ultimately, operators benefit from significantly lower production costs, as well as dramatically enhanced compressed-air availability. Further, service can be scheduled at ideal times, which saves money. And to allay cyber-security concerns, compressor performance data is only transmitted via the closed Sigma Network. Third-party access to the data is not possible.

In addition, Sigma Smart Air monitors key parameters such as service costs, reserves and specific power and enables sophisticated energy and life-cycle management of the compressed air station throughout its entire operating life.

The CompAir Ultima uses two motors simultaneously, each with its own inverter, to individually power each screw.

Twin drives

The new Ultima water-cooled, oil-free compressor from CompAir, a unit of Milwaukee-based Gardner Denver, reportedly provides exceptional performance and efficiency. Part of the PureAir range, Ultima is available in models with drive motors sized from 75 to 160 kW, working pressures from 4 to 10 bar, and flows from 6.7 to 23.3 m 3 /min.

In contrast to the performance offered by traditional motors and drive systems, CompAir has developed the powerful and compact U-Drive unit, a variable-speed, permanent-magnet synchronous motor capable of speeds up to 22,000 rpm. Company engineers said “U-Drive is a true, next-generation motor and one of the mostadvanced compressor drives available today, and ideal for a pioneering product such as Ultima.”

What sets the Ultima apart is the U-Drive uses two motors simultaneously, each powered by its own inverter. Forgoing the traditional single motor and gearbox design, Ultima runs each dry screw air end directly for enhanced performance and lower friction. An intelligent “digital gearbox” links the two U-Drive units, adjusting their speeds continuously. The ability to run both air ends at different rates, depending on demand, means Ultima can precisely match the delivery ratio for optimum efficiency.

Ultima’s unique design uses 20% fewer parts than a standard oil-free compressor, making it 37% smaller than comparable units. And it operates quietly — a 160 kW compressor runs at a mere 69 dB(A). As a result, Ultima can be installed at the point of use rather than in a compressor room. IoT capabilities permit proactive real-time remote monitoring.

Finally, conventional units convert around 94% of compressor energy to heat energy that is easily wasted. To conserve resources, Ultima offers up to 12% better heat recovery than a standard two-stage oil-free compressor. A closed-loop watercooling system extracts heat from all major components and pipes the water out of the machine to be used elsewhere, making Ultima a high-efficiency water heater as well.

Air intelligence

Boge Compressor’s airtelligence provis 2.0 master controller provides intelligent control of all connected compressors. Based on actual air demand, it automatically selects the ideal combination of compressors, optimizes load and idle run cycles and avoids inefficient compressor operation. An air-logic module links individual status values and manages the compressed-air system.

Previously, up to 16 compressors and up to 24 peripheral accessories such as dryers, filters, and valves could be connected. Now, the company’s new higher-level airtelligence provis 3 allows compressors, accessories and compressed air networks to work even more efficiently in unlimited numbers. Based on actual compressed-air consumption, it automatically selects the best compressor combination, optimizes loaded and empty run times, and avoids energy-intensive overcompression.

Units can be configured individually and fitted with a 15.6-in. display with intuitive touch-gesture operation, or ported to a desktop PC, tablet or smart phone. Visualization data can include network pressure, volume flow, pressure dew point, capacity utilization, efficiency of each compressed-air station and electric power consumption, as well as status of the overall system, individual compressors and accessories. It can also display trends such as pressure and compressor performance history.

With airtelligence provis 2.0, Boge already has one of the most innovative controls on the market, according to officials at the Bielefeld, Germany, company. The new higher-level airtelligence provis 3 focuses on maximum energy efficiency, ease of maintenance and customer flexibility. And with integrated Boge analytics and an open data format with OPC UA, it provides a convenient and intelligent solution to optimally meet the high demands of Industry 4.0.

Boge's Compressor's airtelligence provis 3 master controller handles an unlimited number of compressors and accessories.

Plug-and-play compressor

The Nautilus X16 from Vert Rotors, Edinburgh, U.K., is a portable, 20-bar air compressor. The plug-and-play unit, with wheels and a handle much like roll-behind luggage, is designed as a 21st century alternative to traditional, noisy piston compressors.

The Nautilus is a single-stage, micro rotary-screw compressor. Somewhat similar to traditional twin-screw devices, it uses a pair of conical rotors to generate pressure. Vert’s innovation is to place one rotor inside the other, instead of side by side. As air travels along the rotors, internal volume shrinks and raises pressure. Air discharges with pressure ratios of up to 22:1.

It reportedly has double the efficiency of an equivalent scroll compressor and, at around 65 dB(A), runs significantly quieter than a typical piston compressor. It also produces lower vibration, beneficial for sensitive applications. Because the unit can deploy quickly, often in minutes, it can help maintain uptime in critical processes. A traditional compressor might require the installation of a new airline certified for safety — which could be time consuming and costly.

If operation at 300 psi pressure is not required, a manual regulator lets users set the pressure as needed. Air delivery at working pressure is 16 lpm. The system weighs 34 kg and requires 110 or 240 Vac power.

The Nautilus compressor made by Vert Rotors has wheels and a handle, much like roll-behind luggage.

Contactless technology

Tamturbo Touch-Free compressors are direct-drive, high-speed turbo compressors that produce oil-free air for industrial customers. Pressure range is from 3 to 9 bar with capacity from 9.0 to 56.0 m 3 /min. The design is based around proprietary active magnetic bearings that provide friction-free rotation with zero drag and no metal-to-metal contact, so components won’t wear and break down or require lubrication.

The five-axis active bearings rely on real-time measurement and feedback control to hold rotor position with micrometer accuracy, precisely maintain design clearances and eliminate vibration. Built-in safeguards also prevent damage in the event of a power failure, as energy stored in the rotation and in capacitors keeps the bearings energized until the motor stops.

Variable-speed drives control motor speed based on actual air demand to deliver constant pressure. These permanent-magnet motors rotate at speeds up to 35,000 rpm. The VSD and optional diffuser control provide industry-leading capacity turndown range of up to 63% — with excellent idling performance. This ensures the compressor matches air requirements with the best efficiency on the market, according to officials at the Tampere, Finland, company.

Other traditional oil-free screw and centrifugal compressors rely on energy-robbing gears, mechanical bearings, and seals and oil filters that generate friction and lower efficiency. Further, efficiency of an “oil-free” screw deteriorates as Teflon-coatings and other components wear in operation. This reportedly increases energy consumption by 10 to 15% and demands costly overhauls every few years. The direct-driven turbo compressors require no machine maintenance to critical components. In terms of life-cycle cost, Touch-Free compressors provide significant savings in energy consumption and service.

The Sirius NanoLoc from Haug Sauer features a magnetic coupling drive that ensures virtually no leakage.

Smart-phone interface

New PE-VE units made by Bauer Compressors, Munich, Germany, are designed for tough industry conditions and are available with a wide range of compressor options, such as for virtually all uses involving breathing air or nitrogen. The compressors are rated for pressures from 90 to 420 bar and free air delivery up to 620 lpm — or as much as 750 lpm with booster models. Super Silent versions feature a sophisticated soundproofed design that minimizes noise emissions.

The PE-VE’s high-pressure compressor blocks are designed for reliability in continuous industrial use for at least 30,000 operating hours. For example, plasma-nitrided and plateau-honed cylinders with high surface hardness provide long service lives combined with low energy consumption and reliable lubrication of cylinder surfaces, and ultra-low-wear piston rings in the final stage minimize running costs.

Of special note is the newly developed B-App interface that lets users control and monitor compressor systems from a smartphone. The units also have a B-Drain automatic condensate drain system, which ensures that oil/water condensate produced during compression is extracted energy-efficiently, quietly and with minimal pressure losses. To maximize efficiency and economy in operation, the compressors are equipped with energy-saving three-phase motors with IE3 energy efficiency rating as standard.

New PE-VE units made by Bauer Compressors let users control and monitor compressor systems from a smartphone.

Hermetic high pressure

Haug Sauer Compressors, St. Gallen, Switzerland, debuted the Sirius NanoLoc, which produces oil-free compressed air up to 450 bar. With its combination of a high final pressure, hermetic gas-tightness and a wear-free drive via magnetic coupling the system, it is unique in its class and can compress nearly all gases, said company officials.

A magnetic coupling drive permits a hermetically sealed piston compressor, with gas-tight performance at standstill and in operation. There is no wear of the sealing element and no frictional energy loss. The design achieves a permanent leak rate less than 0.001 mbar-l/s.

The NanoLoc design is considered especially suitable for high pressures (>101 bar) because sealing is without piston rings, and there are no frictional losses in the cylinders due to friction-free sealing. Thus, there is lower power consumption and significantly longer service life versus piston compressors with packing rings.

Haug oil-free and gas-tight compressors are considered environmental friendly because there is no oil disposal or gas leakage which can contaminate the environment. Motors are rated from 11 to 30 kW, speed ranges from 970 to 1,450 rpm, and maximum flow rate is approximately 60 Nm 3 /h. Applications range from bottling of industrial gases to power-to-gas storage of wind and solar energy.