HES Tractec has supplied a number of planetary gearboxes for use on the barley germination vessels used in the brewing process, where they had to ensure high levels of reliability while withstanding 24/7 operation in the tough and humid conditions
As a producer of well-know brands such as Carling, Cobra and Coors Light, Molson Coors UK has four brewing facilities, including its Maltings site in Shobnall, Burton-upon-Trent. The company’s Maltings Tower stands around 230ft high and houses germination vessels used in the brewing process. The site, however, was seeing downtime costs rising over the years, so began a major refurbishment programme that included the upgrade of component parts.
The site runs 24/7 so component reliability is essential. The failure of a germination vessel would not only cost the company a batch of malted barley, which is currently 50% more expensive than in 2009, but also the cost to remove wastage from site, disposal and replacement – costing tens of £1000s.
Commenting on the need to upgrade, project and electrical engineering manager, Steve Holyoake, said: “With eight germination vessels in total across the site, if just one of those vessels were
to fail for a day, 1/8 of our production capacity is lost, equivalent to 280 tonnes of barley. There is a monthly servicing programme in place as well as condition monitoring for preventative and predictive maintenance, but with the tower being over 30 years old, and many of the original parts now obsolete or difficult to procure, the decision was made to upgrade and modernise using the latest in technology, both mechanically and electrically.”
When it came to sourcing gearboxes to power the rotating floors of four of the germination vessels, there were a number of requirements – they needed to be durable, reliable, and able to withstand the extreme conditions of the germination vessels, similar to that of 100% humidity.
Having worked with Group HES and HES Tractec for many years, the project sub-contractor recommended planetary gearboxes – manufactured by Comer Industries and distributed in the UK by HES Tractec – to main contractors, Mectek Mechanical Services. For this application, 20 of the Comer gearboxes were supplied. Renowned for their strength and reliability, these more than met the stringent requirements, explains the company.
The vessels, stacked vertically within the 15-storey tower, are consistently held at 100% humidity to encourage the germination process. As the grain naturally generates heat the temperature inside the vessels has to be carefully monitored and controlled or the quality and rate of germination will be affected. As part of this process air is blown through the vessel while it is being humidified.
Each vessel is loaded with barley and this is germinated over four days, during which time the vessel floor rotates at one of two speeds – fast for one hour during loading and stripping before slowing to its normal rate for production. Every 11 hours the floor rotation alternates between clockwise and anti-clockwise to prevent the grain from matting and clumping together. A rotation takes around two hours. After the four days, the vessel is stripped and the barley is kilned for 24 hours. It is then stored, ready for transportation to one of the company’s breweries.
16 Comer gearboxes are used for this application, while four are being held as spares. Each vessel floor works independently, with each gearbox driven through an electric motor. The motors are driven using variable speed drives (VSDs) which not only allows for a more accurate speed change but helps to reduce the output of the gearbox, minimising unnecessary wear and tear. Mounted onto its own frame, the electric motor then powers the rack and pinion mechanism that runs the outer circumference of the floor, powering the rotation.
Now that all the vessels have been refurbished, with one delivered a week ahead of schedule, Holyoake said: “The installation of new technology can improve both the operation and engineering of a plant as well as giving us the reassurance that if things go wrong we can react efficiently with immediate access to spares.”