Applying a frequency converter to a NH3 compressor reduced the energy consumption by 13% at one of the world’s leading palm oil refineries in Malaysia. This equals an energy savings of over 240,000 kWh and the return on investment was approximately 20 months.
Challenge
The palm oil refinery is striving to advance environmental protection and to increase profits by reducing energy consumption. Understanding that applying frequency converters to compressors can result in significant energy savings, they wanted to retrofit a 400 kW ammonia screw compressor with a frequency converter. The customer also wanted to integrate the frequency converter into the existing PLC and DCS systems. After evaluating several suppliers, the customer selected Danfoss because the Danfoss sales team has the expertise to support the integration of the frequency converter into their existing system.
Application Solution
The compressor is being used with two other compressors in an industrial refrigeration system. The frequency converter will allow the first compressor to serve as the trim compressor and will control the capacity of the system. The first compressor and frequency converter will operate continuously. The other two compressors operate at full load when needed for additional capacity. The compressor manufacturer advised that the minimum speed of the compressor is 50%. As a result, the VLT® drive would operate the compressor down to 50% with the slide valve completely open. At 50% speed, the compressor speed would be maintained and further capacity reduction would be performed by the slide valve.
Benefit
Energy usage was measured for one month so that the savings and the payback could be determined. The chart shows the energy consumption of compressor 1 with the frequency converter compared to the energy consumption of the two compressors without frequency converters. Applying the frequency converter to the compressor reduced the energy consumption by 13% (00 kWHrs). This resulted in a cost savings of over $66,500 per year. The return on investment was approximately 20 months. Subsequently the customer has retrofitted many more compressors in the range of 160 kW to 400 kW, achieving further significant energy savings.
This is an application by Danfoss.
Tri-Phase Automation is a Danfoss distributor in Wisconsin.
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