Capacity for 72,000 houses

Hägglunds Drives UK, have supplied and commissioned a new kiln drive hydraulic system at CEMEX’s Rugby works. The plant has a production capacity of 1.8 million tonnes of cement per annum with a single kiln line.

The original Kiln system was rather complex in design and potentially becoming unreliable with difficulty in servicing the pumps and obtaining spare parts within a reasonable lead time and this was an important issue as regards maintaining plant reliability and insurance. A new system using larger Hägglunds SP750 pumps was the answer. This solution eliminated the need for tandem pumps and separate boost pumps thereby simplifying the system. A further improvement by adding a third SP750 pump meant a standby pump was available to provide extra security.

Possibilities for independent control
The kiln, manufactured by Krupp Polisius is 62 meters long and 4.64 meters in diameter and has a vertical static download weight of 700 tonnes through the centre line of the drive tyre by design when fully loaded. It is driven by two friction rollers 2m in diameter and each roller is driven by two Hägglunds hydraulic motors type Marathon MB800. The kiln rotates slowly at around 3.5 rpm and must not stop as it is a critical piece of the plant. All production goes through this one kiln at the plant and an unplanned stoppage with the tremendous heat generated in the kiln would distort the kiln shell and create further potential disruption. Therefore a barring drive is also installed to enable a low power, slower rotation of the kiln in the event of a major failure on the main drive system or it’s power supply, untill the main drive is fixed or until the kiln has cooled sufficiently to be stopped. The drive motors are fed in parrallel from a common power unit and the drive load is shared equally between the four drive motors, naturally, since the hydraulic pressure must be equal at all points in the system. Therefore the two friction rollers share the kiln driving load equally. Although if one roller should start to slip, this would be sensed electronically and there is a back up system to control the
speed of each roller independently, in this unusual circumstance.