Although processors are increasingly looking for auxiliary equipment that can capture and repurpose energy, they might find other opportunities for energy recovery just by looking around their facilities.
That's exactly what happened with Steve Maguire, president of Maguire Products Inc., Aston, Pa. — and most people had never even heard the term "energy recovery" back in 1981, when this story takes place.
Maguire had just become plant manager of Diffus-a-Lite, a small extrusion business owned by his father-in-law. Using a single extruder with a throughput of about 1,000 pounds an hour, the company made light-diffusing panels — 2-by-4-foot panels of flat embossed PS — for suspended ceilings. The line's three rolls were cooled by a chiller, and the heat exchanger in that chiller was cooled by water that ran to a tower on the roof, which simply dissipated the heat into the air. It was a perfectly suitable system — until winter arrived.
"When the weather turned cold, freezing of the tower was always an issue, especially since we shut down for the weekend," Maguire said. As a result, the tower was shut off during the winters, and a large heat exchanger was installed.
"We positioned it in the roof trusses, using standard 8-foot-long baseboard heating sections. They were plumbed together with a manifold on each end, and we then placed valves in the lines to the tower so we could shut off the tower supply [when it got cold] and open lines to the heat exchanger. Then we mounted two ceiling fans above the heat exchanger."
Those fans recirculated the heat, which would have otherwise stayed up in the rafters, throughout the facility. "On Monday mornings, the small plant floor might be as cold as 40 degrees Fahrenheit, but when production started at 9 o'clock in the morning, the factory was comfortable by noon, just by recirculating from that single heat exchanger."
All of the heat generated by melting the plastic — about 100,000 Btu per hour — was kept inside the plant. "That's a lot," Maguire said. "It was more than enough to heat the factory space we were using, and we recovered every Btu. None of that heat was lost to the outside, and it remained the only source of heat we needed in that space."
It just goes to show that in a plastics facility, opportunities for energy recovery aren't limited to the machines themselves.
Mike McCue, copy editor
