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A rapid response protects order opportunities

More often than not, a calciner is a business critical item. If it experiences a catastrophic failure, we need to rapidly attend site and find a solution.

In the case of an industrial minerals manufacturer, we knew that if their out of action rotary calciner – supplied by Mitchell Dryers over three decades ago – wasn’t up and running again in 18 weeks, they’d lose valuable business.

Not surprisingly, many years of thermal cycling at temperatures in excess of 1,000 degrees C had left it in a poor condition. Most of the peripheral equipment had not deteriorated but the heart of the calciner – the shell – had to be replaced.

“The machine had put in sterling service for 35 years, in quite an abrasive environment, and over time the shell had buckled and twisted,” explains Jamie Donaldson, operations manager at Mitchell Dryers. “We looked at whether to replace it with a new machine, but the overhaul option was more attractive to the customer because it reduced the length of the production shutdown.”

Jamie and his team managed to halve the typical programme time to prevent the customer losing precious business. Steel supply was one big hurdle. “To really accelerate the programme we had to significantly reduce the lead time on materials. We had some very open and honest conversations with our suppliers to share the challenges we were facing and see what was possible,” he says.

“Every option had to be explored to meet the customer’s timescales. We were very aware that if they failed to meet their own customer commitments, they could have lost the business overseas and never have won it back. To cover every eventuality, we also had a back-up plan which would have enabled them to produce a couple of tonnes of material in our research and test centre if there were any delays to the project. Fortunately that wasn’t necessary.”

The Mitchell Dryers archive, which holds all of the original drawings, was a valuable mine of information as James Douglas, technical director at Mitchell Dryers explains. “Although we had to transcribe the old drawings into a CAD format, the fact we knew exactly what we were making and how it was put together and installed last time really helped to speed the whole process.”

Whilst the design and the materials used today are essentially unchanged, technological advances mean the team is able to work to far tighter tolerances than were possible thirty plus years ago. “That means the construction process is much more accurate, which results in a better quality end product,” says James.

The installation team had the challenge of the machine being located on the first floor. “We drew up a bespoke lifting plan that took into account the restricted floor space and the limited door opening. We also had a back-up crane, just in case the one the customer had on site should fail and hold us up at the last minute,” recalls Jamie. A team of four engineers from Mitchell Dryers spent a week on site. “Everyone was very clear about their roles and responsibilities and we made sure the customer was fully up-to-speed with our schedule, as we were with theirs.”

Remote working proved very effective for part of the commissioning. “We had a few online meetings between our operations teams, with all of us able to look at the same drawings, to discuss an issue with the insulation and propose potential solutions. It can be a much more efficient way of working,” believes Jamie.

The calciner should now have an extended life of at least 20 years if it’s properly maintained. “Increasingly, customers are asking us to regularly inspect their equipment for signs of wear and upcoming problems so they can reduce the risk of any unplanned production downtime. We have the experience to look at gear boxes, bearings, rollers and running gear and see what maintenance is needed.

“For example, we can offer customers inspections or services every three or five years, to coincide with their plant maintenance schedules. The best option is always to do all you can to prevent failures happening, and that’s what our planned preventative maintenance programmes are designed to do.”

Related Solution

Directly Heated Rotary Dryer

Related Industry

Mineral

Related Solution

Directly Heated Rotary Dryer

Related Industry

Mineral

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