Executive Summary

When it comes to the selection of plant blow-off and drying systems, manufacturers today are
presented with a multitude of challenges and options. Many are weighing the viability of full system
replacements that promise increased energy efficiencies and improved reliability. Others seek the
flexibility of component level upgrades that provide localized, modular drying solutions for a particular
phase of the manufacturing process. Adding to the complexity of making the right decision, plant
operators must also consider the costs and benefits of using a compressed air solution versus a
blower-driven alternative.

Only a few years ago these decisions were largely driven by economic considerations. Today, other
factors are considered such as improving energy efficiencies and minimizing the environmental damage
in manufacturing settings, encouraging the plant operator to also improve his “green” stance. From
pharmaceutical and medical industries to food/beverage and electronics, industries that rely on blow-off
and drying systems are now taking a closer look at finding solutions that improve performance, lower
operating costs and reduce negative environmental impacts. This paper will explore the costs (both
upfront and life cycle), benefits and environmental impacts of using blower-driven solutions versus
compressed air. It will also provide the plant operator with the tools to make the best decision for his
specific drying application.

Compressed Air Systems

Flexible Deployment for Every Application

As many manufacturing facilities operate one or more large compressors that supply compressed air, these systems are often the default choice for processes that require air for cleaning and blow-off. Compressed air systems provide versatile, flexible drying with installations that can be made available throughout the plant. Because of this, compressed air delivery systems are often viewed as an acceptable fixed cost in a plant and may even be overlooked when process improvements are proposed. Plants incur a higher energy footprint (economic and environmental) as a result of their compressed air systems. The versatility and availability of these systems for usage in multiple applications prevent most plant operators from considering alternatives.

Figure 1 illustrates how a typical compressed air distribution system operates.

Energy Consumption and Compressed Air Production

Plant operators must fully understand the amount of energy consumed in a compressed air system, and then evaluate if it is the best solution for the plant’s particular drying applications. A compressed air system consumes 8 hp of energy to generate 1 hp of compressed air, making it one of the most expensive uses of energy in a manufacturing plant. Depending on the application, compressed air generation consumes from 10% to 30% of a facility’s total electricity usage.

Once generated, compressed air is stored in tanks where it can be distributed through transport lines to various points of use across the manufacturing plant. Significant losses of compressed air, due to leaks that occur during storage and transportation, are inevitable, and, more importantly, not recoverable. Oil and unwanted debris in the transport lines often increase maintenance effort and costs. Frequent maintenance checks and periodic filter replacement are important factors in keeping air quality high. Annual maintenance costs can amount to 10% of the initial purchase price of the compressor which can range from U.S. $30,000 to $50,000.

Primarily designed to operate pneumatic equipment at the plant, an air compressor provides air at pressures of 100 psi and greater. Considering that most blow-off applications require only 2-3 psi, it is evident that amount of energy is wasted (in this case up to 97%). Of course in applications where more psi is required for faster, comprehensive drying, the amount of wasted compressed air decreases. It’s important to remember that the higher the pressure the compressor produces, the greater the potential for energy inefficiencies when distributing to blow-off or drying applications.

Energy audits have revealed that a single 1/8" nozzle blowing at 100 psi 24/7 costs approximately U.S. $20,000 per year to operate. Surprisingly, compressed air is seldom considered as a contributing cost of production and is typically blended into overhead. This hidden cost must be brought into the light and evaluated closely to ensure that selecting a blow-off alternative at any (or all) drying stations would be more cost effective. Calculating the operating costs of compressed air systems for specific end uses allows you to determine if compressed air should be used in specific applications or if other electric-motor operated equipment (such as fans or blowers) would be more efficient.

To help determine operating costs, an important first step is to conduct a comprehensive energy audit to analyze the energy consumption patterns of compressed air and identify potential opportunities for energy usage reductions. Once these costs have been calculated, plant operators can take a step back and evaluate energy and maintenance expenses of each application of the compressed air delivery system and decide if the solution is the most efficient drying choice.

Blowers/Air Knife Packages

Viable, Energy-Efficient Alternative to Compressed Air

Blowers are widely recognized as an energy-efficient alternative to compressed air delivery for blow-off or drying. Electric motor-driven, blowers are capable of producing high-velocity dry, ambient or heated airflow that can be purified to high levels via a variety of filtration options – at significantly less energy consumption than a compressed air system. In drying stations where compressed air delivery is cost prohibitive, blowers can be easily installed close to the application to replace existing blow-off devices. Unlike compressed air systems where oil and other debris pose contamination risks, blower technology has advanced to offer low-maintenance, high-performance airflow without contaminants.

Energy Performance and System Costs

Blowers can easily be installed at any drying station in the manufacturing process. But, because blowers do not rely on existing plant infrastructure (as is the case with compressed air delivery), blowers require more of an upfront investment to integrate. But, with up to 80% less energy consumption over a compressed air station, blowers offer a return on investment in less than a year. For example, analysis of a six-comb nozzle, 30 psig compressed air blow-off showed operating costs of U.S. $6,350 compared to only U.S. $550 for a 3 hp blower system with a single manifold and six inline nozzles.

Blowers are capable of delivering continuous, accurate, fixed airflow volume and velocity for reliable blow-off in a variety of industrial applications. Adaptable to any conveyor with line speeds of up to 2,000 feet per minute, blowers offer the potential for increasing the speed of conveyor lines up to 50% while reducing loss rates. Following is a sampling of applications where blowers have successfully replaced compressed air in the manufacturing process:

• Product and parts drying
• Liquid or particle blow-off
• Dust and debris blow-off
• Coating control
• Conveyor belt cleaning and drying
• Controlling surface coatings
• Conveying, holding down or cushioning materials with air
• Cooling or heating materials
• Providing an air curtain or barrier
• Separating different weights or sizes
• Surface impregnation
• Leak detection
• Corrosion prevention

Lower horsepower (3 hp) blower systems typically require an investment of less than U.S. $5,000 and are relatively easy to install. This blower system is recommended for applications where lower speed processes require more time for drying. In applications where high-speed manufacturing lines require fast drying, a 20 hp blower system is recommended. A 20 hp system can cost up to U.S. $15,000 and requires an additional installation investment (electrical wiring, hardware kits, mechanical installations and tubing/piping installations) of approximately U.S. $2,500.

Many newer blowers are fitted with inlet and outlet filters to ensure very high air qualities capable of achieving up to 99.97% purity levels, at a much lower unit and maintenance cost than compressors. Most general manufacturing applications can accept the quality of air generated from these blowers, but certain clean-room applications that are highly sensitive to air quality will need to verify that appropriate filters are available for a particular blower system prior to making the investment.

The biggest concern with high-performance, high-velocity blowers is usually noise. In some cases noise levels can exceed the OSHA specifications. If your application is noise-sensitive, work with your air product’s manufacturer to suggest a blower solution that is specifically designed with noise-abating enclosures. Most recent advancements in blower enclosures have been able to address noise issues considerably well.

Conclusion

Blowers and compressors have seldom been viewed as comparable systems for blow-off cleaning or drying applications. While each has its own intended uses and inherent benefits, the two have rarely crossed paths or been used interchangeably. As blowers offer a flexible solution to augment your least efficient compressed air delivery station, it may be time to consider the modular scalability of installing a new blower system. Compare the benefits of each system to help decide what the most viable blow-off option is for your particular application.

Benefits Analysis of Blowers vs. Compressors

On the whole, blower systems outperform compressed air systems in almost every possible category. As modular solutions with a small physical footprint, blowers offer ease of installation and provide high-performance, low maintenance solutions regardless of plant scale.

The variety of blowers in the market provides a multitude of performance requirements and configuration options to meet manufacturers’ many demands. Be sure to research the alternatives carefully and align the available options closely with your application requirements before making a decision.