Bathroom-ware manufacturer Twyfords is set to save £14,000 per year following installation of variable speed drives from ABB at its Stoke-on-Trent plant.
Twyfords, which makes 1.25 million toilets a year at the plant, was interested in making energy savings following the introduction of the Climate Change Levy and asked ABB’s channel partner HG Rewinds to undertake an energy audit on its two firing kilns.
Ian Shingler, Kiln Manager for Twyfords, says: “The output of the exhaust fans on top of the kilns was controlled by a slide damper, which was set at 25% to get the correct exhaust flow. This meant we were wasting 75% of the energy we put into the motors and there was obviously a lot of room for improvement.”
HG Rewinds undertook a full energy audit of the kiln area and fitted a sample variable speed drive to demonstrate the results that could be achieved. This showed that each drive could save £2,389 per year on running costs. Six ACS 400 drives from ABB have now been installed on the kilns, two 15kW and four 4kW. With a total order value of £20,000, this gives a payback time of only 1.3 years.
As well as the energy savings, the drives are bringing several other benefits. Using a pressure transducer and a 20mA set point controller, a control loop has been set up to maintain a constant air pressure in the kiln by balancing the input and output airflows. This prevents negative air pressures developing that would suck too much cold air into the kiln, affecting critical stages in the firing process. The control loop smoothes out variations in the process and helps Twyfords maintain a constant product quality.
The drives also take out the peak start up current. This extends the life of the control contactors, which previously had to be replaced every 12 months.
Shingler adds: “HG Rewinds designed and installed the application and acted as our link between the sub-contractors and ABB. We have been very pleased with both the service we received from them and the performance of the equipment.”