Compressed Air Best Practices - February 2008 - (Page 34)

| 02/08 Focus Industry BULK HANDLING | THE INS AND OUTS OF VACUUM GENERATORS and facilities with large numbers of these devices may have issues maintaining adequate supply pressure. These facilities will typically have several “extra” compressors online to maintain site pressure requirements. Replacement of vacuum generators with electric vacuum pumps will allow for large horsepower compressors to be taken off-line and be replaced with much smaller horsepower vacuum pumps. An average example would be taking a 100 horsepower air compressor off-line and replacing it with a 25 horsepower dedicated vacuum pump. The associated compressed air filters and dryers will also be shut down. Not only are there energy savings in this case, there are also savings for maintaining smaller pieces of supply equipment. As an added benefit, it is far easier to maintain site compressed air pressure with a lower demand requirement. their simplistic design and ease with which varied materials of construction can be used. Environments with heavy particulate loads, especially where particles are very small, seem to lend themselves more to these types of systems. This is in part due to the filtration requirements of many electric vacuum pump designs. When a majority of particulates are smaller than one to five microns in diameter filtration systems tend to become relatively large for an electric vacuum pump. Designs for vacuum generators have been changing in recent years and they are definitely more efficient than they used to be. They have also become less sensitive to compressed air supply pressure. Older designs required high pressure for normal operation. When supply pressure dropped, so did performance. New designs also incorporate energy saving controls to shut off the compressed air supply as needed and vacuum sensors to detect when parts are not present on robotic arms. These types of advancements open up more applications for vacuum generators and make them appropriate for other uses. The end result is that if energy reduction is your aim, finding alternatives to vacuum generators is a prudent course. Otherwise, it seems that vacuum generators are one of those sinful conveniences that many owners know about but are not willing to do without. I believe the reason is that these devices can be so versatile and capitally inexpensive that the energy downside is swept aside or not measured at all. Whether efficiency or appropriateness is more important, each vacuum generator should be individually evaluated to ensure it is the best technology to do the job. BP For more information contact Dan Bott, Dan Bott Consulting LLC, tel: (251) 609-1429, email: dan@dbott.com, www.danbottconsulting.com CO2 O A good rule of thumb average is that electric-driven vacuum pumps are four times more energy efficient than compressed air-driven vacuum generators. kW Appropriate in Contaminated Atmospheres When considering the appropriateness of using vacuum generators there is not as much clarity. In applications where there are a large number of vacuum generators in a small floor area, it is much easier and economical to use a centralized vacuum system. However, in applications where there are just a few vacuum generators in a large floor area, it is not as practical to use electric vacuum pumps especially if compressed air is the only pneumatic supply within a reasonable distance. If adequate electrical service is not locally available, adding sufficient electrical supply may be an expensive endeavor. In processes where mobility is needed, vacuum generators are as equally mobile as electricdriven vacuum pumps and can be much smaller in physical size. In applications that generate corrosive vapors, venturi-style vacuum pumps are a viable choice given 34 www.airbestpractices.com http://www.danbottconsulting.com http://www.airbestpractices.com

Table of Contents Feed for the Digital Edition of Compressed Air Best Practices - February 2008

Compressed Air Best Practices - February 2008 Contents From the Editor Utility-Air News February Audit of the Month: Dense-Phase Transport System Wreaks Havoc on Compressed Air System Real World Best Practices: Material Conveying with Pneumatic and Vacuum Systems Industrial Vacuum Cleaners Use Compressed Air in Portland Cement Manufacturing Processes The Numatics Air Preparation Group The Ins and Outs of Vacuum Generators Dekker Vacuum Technologies Do Your Meetings Sabotage Your Profits? Resources for Energy Engineers Wall Street Watch Advertiser Index Job Market

Compressed Air Best Practices - February 2008

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