Northern Foods is saving nearly £2,500 annually on its compressed air system since installing an ABB variable speed drive at its Riverside Bakery in Nottingham. The 45 kW drive was supplied by Inverter Drives Systems (IDS), an ABB Drives Alliance member. Compressed air is used in many of the bakery’s processes. As part of the company’s continuing efforts to cut energy costs, Northern Foods decided to investigate its compressed air system and asked Inverter Drive Systems to undertake an energy appraisal and make recommendations.
James Whieldon, maintenance analyst for Northern Foods, says: “Our monitoring and targeting software gives us profiles of the compressors and indicated that there were definite opportunities to improve the amount of energy they were using. We had used Inverter Drive Systems before and know them well so we were happy to use them again.”
IDS confirmed the energy use figures recorded by Northern Foods and recommended the use of a 45 kW ABB standard drive.
There are three compressors in total, two 30kW fixed-speed assist compressors and a 45 kW duty compressor. The drive was fitted on this compressor, which is in operation all the time. One of the fixed speed 30kW compressors is used to top up the pressure when demand increases, while the other is on standby in case one of the others goes down.
IDS saves Northern Foods £2,500 a year
Zac Dorn of IDS says: “There are always two out of three compressors running so we had to ensure that the fixed-speed assist compressor only came online when the duty compressor with variable speed drive could provide no more air, that is, when it is running at full-speed.”
This was achieved by the installation of a pressure sensor to provide accurate system pressure feedback for the drives built-in PID controller. The contract also involved installation, modification of the existing control circuit to accommodate the drive, commissioning and post-installation energy monitoring.
Says Whieldon: “The drive is now operational and we calculate the actual payback time of the project is 1.5 years, achieving an annual saving of £2,450. But with energy prices rising, the monetary savings will increase.”
Pleased with the project, Whieldon adds: “We knew that IDS could complete the job quickly and they were the only company we asked to quote. They perform accurate energy monitoring and investigate the installation thoroughly. They are timely, give you the information you require and deliver good savings.”