01 February 2013

Energy saving compressor units: Is a VSD compressor unit the best solution?

Can a Variable Speed Drive (VSD) compressor lower the operation cost or create higher costs in fields other than energy?

Reducing energy costs is becoming a top priority, so it's no wonder that VSD compressor units are increasing in popularity. There is a common belief that VSD compressors are the most efficient part-load rotary screw compressors. As much as I agree with the high quality of VSD compressors, I cannot stress more the importance of fine tuning and adjusting the compressor unit to the field working conditions.

For example, at full load, a VSD compressor increases power draw by 2%. The way to compensate for this loss is by using a permanent magnetic E-motor, which saves 4% of power.

Fine tuning of a compressor unit is the key to saving energy, which involves searching for the optimized ratio of cooling energy to input energy.

Fine tuning is the last task in the compressor unit construction process. I must admit that in some cases, a compressor unit well-optimized for energy saving might be up to 35% more expensive than a standard VSD compressor unit. But why is this?

The answer lies not only in the component’s design, investigation, research and development, but also in the flexibility of the component cooperation. Most importantly, some compressor units are not sufficiently equipped with certain composition systems, so optimal performance is not achieved in every working condition.

In most cases, the initial purchase price of a VSD compressor unit only accounts for about 20-30% of the total cost of ownership over 35 years. The majority of the cost comes from the electricity used to operate the machine and also the unit’s maintenance. A flexible, well balanced and efficient compressor aggregate can be the difference between quick payback time versus a negative investment result in the first five years.

You can either pay more for quality and flexibility up-front, or add the modification to your compressor after a few years of service. However, modifications afterwards are, in general, more complex and thus more expensive. Besides the stress of added expense, loss of production time before action will have a negative effect on your total investment.

If you have questions regarding your new purchase, don’t hesitate to take advantage of our new consulting services; we are happy to help you!

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