Insulating for Energy Efficiency

Posted by Abel Covarrubias on Mar 18, 2015

Efficiency is the name of the game. The more efficient one becomes, the greater the chances of being successful. With electrical and natural gas costs constantly rising over time, we have a duty to find ways to conserve more energy. With that in mind, the insulation of the HMA hot plant drums, at our A.R. Wilson Quarry, is a perfect example of this energy conservation.

In the production of Hot Mix Asphalt (HMA), the drum is used to dry and heat aggregate to a workable temperature, to mix and produce HMA, typically around 300 to 325 degrees Fahrenheit. In the past, the drier drums were bare metal with no insulation; which resulted in significant heat loss to the atmosphere.

To evaluate the energy savings potential, an audit was conducted and the dimension of each drum, average internal temperature, and historical production data was taken. 

Drum Insulation Benefits

With the new insulation, and heat retained within the drum, the burner has operated at a lower rate while maintaining uniform temperatures throughout the length of the drum, thus reducing consumption of natural gas and capitalizing in fuel savings. This initiative resulted in a 95,000 Therm reduction in natural gas, amounting to approximately $38,000 in annual savings. Other potential benefits include:

Faster warm-up

The initial warm up period will be cut approximately in half

Increased Production

Recaptured heat provides increased production capability provided the exhaust air system has ample reserve capacity.

More Uniform Heating

Evenly spread temperatures replace concentrated “hot spots” resulting in more efficient heat transfer to material.

Instant Restarts

With the internal temperature of the dryer drum retained between cycles, restart operating temperatures are almost instant.

Reduced Exhaust Emissions

A lower burner operating position equates to lower exhaust emissions. This helps in meeting state air permitting requirements as well as protecting the environment.

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