7-day energy analysis
IDS agreed to find and implement energy savings on a ‘no savings, no fee’ basis. The project initially involved a seven day energy analysis of the existing direct-on-line controlled condenser fans on the refrigeration plant to establish operating costs at fixed speed. The four fans had a combined measured power of 38 kW. The refrigerant gas enters the condenser, where fans are used to help cool it down to atmospheric temperature and turn it back into a liquid, ready to expand and cool once again.
IDS used the head pressure signal to control a variable speed AC drive to keep this pressure perfectly at its design point, varying the fan’s speed to meet the chilling demand.On completion of the project, a further seven day energy analysis was carried out and the savings and payback periods calculated. It was shown that the drives on the four fans had saved 13 kW in total representing an annual saving of £7,400.
As well as the energy saving on the condenser fans, the reduced on-off cycling of the refrigeration plant lead to a further 10 percent reduction in compressor power. It also significantly reduced fan noise, improving the environment for neighbouring properties.
Drives were installed on other processes including air compressors and water pumps, and the facility is now making energy savings of £25,000 a year after installing £16,000 worth of ABB general purpose drives. The original forecast estimated that payback would be in 12.6 months, yet actual payback time was only 7.7 months.
Darren Bolton, Operational Improvement Manager at Cherry Valley, says: “IDS’ theoretical results were all backed up with good graphs and charts. Quite simply IDS are very, very good - we doubted the energy savings and needed IDS to prove each drive in turn. That also gives you trust in your partner because if the proof was not there, we simply did not have to pay for the drives.
“ABB is a worldwide brand with a first class pedigree so that gave me confidence to know I was making the right choice.”