Less hot air

Drying machines, one of the most costly and wasteful pieces of industrial equipment, are being transformed into energy-saving devices. Siobhan Wagner reports.

Food and drink manufacturers could significantly reduce their power use with a drying machine that releases compressed or blown air only when a product is ready to be treated.

The new technology is the result of a Knowledge Transfer Partnership project involving Hertfordshire University and UK production drying specialist Secomak. The company’s Powerstrip hybrid drying machine is now being used by Magners and Scottish & Newcastle.

David Dell, product development manager at Secomak, said that drying processes are responsible for 17 per cent of the UK’s industrial energy consumption. Much of that is wasted, he said.

Dell said his company’s studies of drinks manufacturers such as Coca-Cola and Britvic showed many air machines run all the time even when no product is waiting to be dried. He said this happens about 30 per cent of the time during the production cycle.

In some cases, said Dell, the dryers stay on even when production is shut down on maintenance days. ‘Energy is now so expensive for industry it is going to be looking at every possible way to save it,’ he said.

The Powerstrip is equipped with sensors, which can detect when a product needs to be dried.

If, for example, a row of beer bottles entered the machine, the sensors would detect their presence and alert the central control unit to start up the process.

The machine would engage stainless steel nozzles that could, among other things, shoot compressed air underneath the bottles’ crown corks and dry them. Alternatively, blown air could be released through slots on the side of the machine and driven across the surface of the bottles to dry them for labelling.

Dell claimed this is the first machine of its kind that can control the cycle of both compressed and blown air.

The technology, he said, is based on one from O.N. Beck, a compressed air drying specialist acquired by Secomak in 2005.

O.N. Beck developed a compressed air drying unit with sensors that alert an electronic control system to cut off the supply of air when gaps occur or objects are stationary on the conveyor line.

Dell, who used to work for O.N. Beck, said the main challenge for Secomak was applying that technology to blown air.

One main hurdle to overcome, he said, was dealing with the pressure differences between blown and compressed air.

‘A blown-air system runs at an eighth of a bar. A compressed air system runs at four bar,’ he said. ‘One is running at 32 times the pressure of the other.’

The second challenge was trying to control the large electric motor used to blow air. Dell said his research group worked with Mitsubishi Electric to develop electrical inverter frequency controls and intelligent electronics that could be imbedded into its programmable logic controllers.

‘We used the one that O.N. Beck had come up with for controlling any form of compressed air-driven system, then moved that into the world of blown air,’ he said.

In addition to reducing energy consumption, Dell said the Powerstrip machine can also reduce the average noise output of the drying process. Factory workers no longer have to listen to the constant whine of the dryers because they only run when required.

An overall noise level of 85 dB(A) over an eight-hour working period would fall to 80 dB(A) he said.