Even greater energy savings with new variable speed compressors
July 27th 2007

Companies wanting to reduce their operating expenses should not overlook the cost of providing compressed air, which is a major item in the energy balance of most companies. Variable Speed (VS) screw compressors help reduce these costs significantly (up to 35% savings). VS screw compressors have been supplied by Gardner Denver since 1998, which has made the company a pioneer in this field.

The desire for a global product with class beating energy efficiency led to a radical approach to the latest design, with all aspects of energy consumption within the package being put under the spotlight.

THE SPECIFIC ENERGY CONSUMPTION IS REDUCED BY 13 %.

The energy/flow characteristics of the ENDURO-Plus profile air end are almost constant throughout the speed range. This contrasts with traditional air end designs that emphasize full speed capacity at the expense of part load efficiency, so important with VS compressors.

The main drive motor (insulation class F, IP 55) and inverter package has a very high efficiency across the full speed range, plus a flexible drive coupling eliminates belt drive energy losses. Depending on the rating and age of a machine, a vee-belt drive can account for a loss of between 1.5 and 2.5 %.

Throughout the life of the direct-coupled machine, these savings accumulate dramatically. “Lifetime energy costs far outweigh initial purchase costs, and users are now starting to realize the importance of this in their decision-making “ says Trevor Perry, Sales and Marketing Director of Gardner Denver. Typically, a temperature dependant wax element would control the oil flow. But this element does not consider the intake temperature and so is imprecise, slow to respond especially when the machine is cold.

The proportional oil mixing valve in the new, directcoupled VS screw compressors avoids these drawbacks, such as increased wear and tear of the oil, degradation of the oil quality and higher corrosion risk. . This results in the best thermal efficiency in the air end without the possibility of condensation. “We designed the highest possible operational safety, economy of operation and service life in the new VS machines“, Trevor Perry underlines.

LOWER NOISE LEVELS

For optimal efficiency of the cooling air, the new VS compressors have separate flow paths for the air intake, cooling fan and inverter. The result is extremely low noise levels, 64 dB (A) at part load.

Our VS compressors offer significant operational advantages in a wide range of end user applications,” adds Trevor Perry. “Importantly, in these energy conscious times, they offer opportunities to keep costs under tight control while increasing the output of ontap compressed air. They are certainly the compressors of the future and Gardner Denver is in the forefront of their development and manufacture.”

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