Dec 2011: Michelin Invests in Cooling Tower to Achieve Greater Energy Efficiency

In a world that is increasingly speeding towards a global energy crisis, it is heartening for us to report that Michelin has invested in a cooling tower in its Dundee (Scotland) plant that will cut the plant’s annual energy consumption by a figure of 1500 M Wh.

Those of you following this blog regularly may recall a news item discussed here sometime back about Michelin’s investment in capacity expansion at its Dundee plant. The capacity expansion has in fact resulted in creation of 140 new positions, enhancing local job opportunities.

The Details

The cooling tower that has been installed incorporates AC drives, which control the speed of the cooling equipment within like fans and pumps, making them respond in a manner related adequate with relation to the demand requirements.

When the cooling plant is idling and the demand for power is low, the AC drives ensure that the energy consumption is as little as that required of boiling a cup of tea. The AC drives have been supplied by Emerson Industrial Automation Company – Control Techniques.

Variable Speed Drives – Need of the Hour, Says Control Techniques

Control Techniques Project Manager, in charge of the Dundee project Mr. Mike Barklie said that while assessing possible avenues to achieve energy efficiency, it emerged clearly that considerable savings both in terms of energy and associated costs could be achieved through the use of variable speed drives.

These drives speed up or slow down the fans depending on whether the requirement for supply of cold water is high or low respectively. Mr Barklie admitted that it was no doubt a major investment for Michelin, but he added that savings associated would offer a handsome return on investment within less than three years.

How Does it Work

The fans in the cooling tower are categorised as main and standby.

The main fans begin to function initially and the standby drive becomes effective and is initiated into action only when the demand on the main fan drive goes beyond 60%.

The minimum speed for the fan is 40% of the maximum speed and corresponds to a power requirement of 2.5kW, the condition when the plant is idling.

In the older cooling tower, which did not have the variable speed drives, even in the idling condition, there was no way to control the fan speed and thus the energy expended. To understand better before the Control Techniques drives were installed, power expended by plant during idling was 90kW.

Some Numbers

With the use of these new drives, the average power consumption in the Dundee tyre plant has dropped to 66kW per hour from 242 kW across all fans and pumps associated with the water cooling system.

This translates into a saving of 186kW per hour or 4 M Wh per day.

The Control Techniques drives have been installed in the Dundee plant on pumps, stirrers, extruders and other equipment. The cooling tower installed is the SPX-Marley high efficiency tower that has two 30kW fans and six large pumps. 3 pumps bring hot water to the tower while the other 3 supply chilled water to the various processes in the factory.