“This new bearing system reduces energy consumption by up to 10 percent.”

Johny Bultheel, Plant Manager, Argex

Working together with SKF, Argex has improved the reliability of its rotary kiln for enhanced safety, while significantly reducing energy consumption and costs.

Located in Belgium, Argex mines around 1,000 tonnes of clay every day for a production capacity of 500,000 cubic metres of expanded clay granules every year. Used primarily as a building material in a range of applications, the granules are baked in a 76 metres long, two-part rotary kiln. The largest kiln of its type in Europe, it turns continuously, day and night, processing around 50 tonnes of granules every hour. The kiln is heated using lignite and runs for two to three months at a time before being stopped for a maintenance interval of two to four weeks.

The challenge

The rotary kiln is supported by eight support roller units, each containing two bearings. Historically, these were equipped with bushings or sliding bearings, but a better solution was needed. “The main reason for this is the safety issue stemming from the unreliability of the sliding bearings,” explains Johny Bultheel, Plant Manager at Argex. “When we restart the kiln after replacing the support roller, the bearings have to be aligned absolutely perfectly. If this isn’t done accurately, the lubrication doesn’t function correctly; they can heat up the lubricant and ignite.”

The Argex plant has seen two roller fires in recent history due to misalignment in the bushings. Sometimes this overheating happens immediately, other times it can take a week before the problem is detected. In any case, production must be shut down to make the necessary adjustments. Adding to the problem, the skills needed to adjust the older sliding bearings are being lost as the workforce is renewed over time.

The solution

Argex knew that something had to be done and decided to replace the support roller units, beginning with a first set of two. SKF was asked to come up with a simpler, more reliable solution. The project began in 2008 under the supervision of George Cant from the maintenance department. The study took some time as SKF was asked to supply not just the bearings, but also the support roller and shaft, housings and base plates, with exactly the same overall dimensions as the previous solution, to facilitate and minimize the cost of the installation. The new support roller units, each weighing some 23 tonnes and equipped with an automated SKF lubrication system, were installed in August 2010.

Customer value

“What we wanted from SKF was a simpler, more reliable solution,” says Bultheel. “Another driver for converting to roller bearings is energy consumption. We were looking for a more modern solution with a better lubrication system and thus lower friction that could help reduce costs. This new bearing system reduces energy consumption by up to 10 per cent. Everything went smoothly, and the bearings have worked perfectly.”

Argex is currently looking to replace the second set of support roller units on its rotary kiln.

Argex challenged us. Now it’s your turn.

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