CNES replace kiln support roller shaft at Cauldon works
CORUS Northern Engineering Services (CNES) have successfully manufactured and installed a kiln support roller assembly on the 58m long rotary kiln at Lafarge Cement’s Cauldon Works in Staffordshire.
Over the last two years, CNES have manufactured and refurbished more than £1 million worth of kiln support roller-shaft assemblies for all the major UK-based cement manufacturers, but this is the first time the company has been involved in installation work in the cement industry.
Cauldon Works has the production capacity to manufacture up to 1 million tonnes of cement each year and is increasing its use of waste-derived fuels as part of its drive for increased sustainability in its operations. The works uses a combination of traditional fossil fuels – coal and petroleum coke – with tyre chips and processed sewage pellets. It is also permitted to use recovered fuel oil (RFO) and has recently been given a permit to evaluate solid recovered fuel (SRF), which, it is estimated, could reduce its carbon dioxide emissions by around 17,000 tonnes each year.
One of the existing kiln support roller shafts at the works needed replacing as it was badly worn. The roller shaft is one of six that support the kiln. The rollers themselves weigh between 8–9 tonnes each and have a typical operating life of around five years.
Lafarge decided to replace the worn shaft at the next available plant shutdown, which was in February 2008. However, due to the height and accessibility of the unit under the kiln, the company decided to outsource this work to an experienced contractor, who would be responsible for removing the old roller and installing the complete new roller shaft assembly.
Stephen Haywood, project engineer at CNES, commented: ‘We have a very close working relationship with Lafarge and this, coupled with our vast experience in heavy lifting, removal and installation work, resulted in Lafarge inviting us to tender for the installation work, as well as the manufacturing of the replacement roller shaft.’
Having secured the contract, the removal and installation work took five days to complete. First, in order to remove the existing damaged roller shaft, CNES engineers had to jack up one end of the kiln. This was carried out using two 150-tonne hydraulic jacks with the roller being removed in a two-day time frame, a process that involved moving it out of position on skates using lifting slings and lifting beams, connecting to chain hoists and lowering it 8m to a sunken floor. The roller was then removed from site for scrapping and recycling of the steel.
Fitting the new roller was effectively a reversal of the removal procedure. The rotary kiln was then lowered back on to the new roller shaft ready for commissioning by Lafarge’s engineering team. In total, CNES engineers spent around eight days on site.
As well as the removal and installation work, CNES manufactured the replacement roller shaft assembly. CNES Scunthorpe manufactured the shaft and then machined it to suit the roller at Corus Process Engineering (CPE) in Workington.
Alan Holgate, estimating engineer at CNES, commented: ‘For Lafarge at Cauldon, we manufactured the forged steel shaft at Scunthorpe, while the roller forging was delivered to CPE Workington. Engineers at Workington machined the inside diameter of the roller, for Scunthorpe to machine the shaft to just one thousandth of an inch larger than the roller bore.
‘The shaft was shipped to Workington, where the roller was placed in an oven to expand the bore before it was dropped on to the shaft to cool down to a tight fit. Once this had taken place, the main diameter of the roller was machined in a large lathe to the required dimensions and concentricity, before final inspection and despatch to Lafarge.’
