Automatic Electric Heat Ends Pre-Dawn "Light-Offs" At Asphalt Plant

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The Challenge
No one likes to get up and go to work before the sun comes up in the morning, especially on cold winter mornings. This made it hard for this asphalt producer to hire reliable employees to light-off its boiler at 3 A.M. to heat the cold, sluggish asphalt so that it could be mixed.

The Solution
To eliminate the problem, metal-sheathed electric heaters, thermostatically and timer controlled, were installed.

In the past, only the asphalt in the tanks was heated, and it was sometimes 10 A.M. before the pumps themselves would operate, delaying the day's work drastically. It was also necessary to heat the asphalt further with heaters on the distributing trucks until it was hot enough to spread. 

Strip elements are installed in the circulating pipes in the bottom of the tanks, under the coverings for the pumps, and along the pipes to and from the tanks. Around the bin in which road patching material is mixed, tubular heaters are installed in what was once a steam jacket, permitting mixing any time of any day. Temperatures are maintained between 100-250°F, and, when the sun and pumping keep the asphalt liquid, the timer restricts the electric current to all heaters to one-third of the value used during off-peak night hours.

The Benefits
Costs have been reduced, closer temperature control has been realized, and operation has been 100 percent reliable.