![[ Blue Circle Cement Kilns ]](../images/applications/bcc_kilns.jpg)
Blue Circle Cement Hope works in the heart of the Peak District as part of a £26 million plant upgrade program needed to completely replace their two rotary kiln drive systems. At 70 metres long, 5 metres in diameter, each of the kilns weigh in at some 900 tonnes.
The overall aim of the project was to optimise production performance, reduce emissions and overall performance. The two kilns at the works, which make over 1 million tonnes of cement a year, are fed with a mixture of shale and limestone taken from two quarries further along the site. The feedstock is milled to a fine powder and is gravity fed though a series of pre-heater cyclones taking the product up to around 800°C using hot gases from the kiln.
The original 35 year old 'Lawrence Scott' 445HP motors had very limited speed ranges between 200-980 rpm, and could not meet the demands of higher production targets.
Calculations showed that the original motors were capable of a starting torque of 2915 ft/lbs. Two new motors of 315kW were chosen by Newton Tesla, each motor weighing over 2,200kg and was forced ventilated.
![[ Kiln Drive Motor ]](../images/applications/kiln_drive_motor.jpg)
Mitsubishi MT-A140 drives of 375kW each were chosen to give the required motor torque to 'unstick' the kilns at start-up.
![[ Kiln Drive Control Panels ]](../images/applications/kiln_drive_panels.jpg)
The new kiln drives now have a speed range of 60-1500 rpm at the motor shafts, and a maximum kiln speed of 2.2 rpm.
Both inverters were auto-tuned in the 'flux vector' mode and are controlled via a 'Melsec Mini' fibre optic network.
Blue Circle chief engineer - Mike Franklyn says: "Many companies supply very good equipment, but understanding the application and coming up with reliable solutions is far more important. We get an excellent service from Newton Tesla in this respect!"