Waste heat recovery system will generate power for NC lumber mill

By Lisa Gibson | May 31, 2011

By the end of this summer, a Weyerhaeuser lumber mill in Greenville, N.C., will be utilizing organic Rankine cycle technology to recover waste heat from its biomass-based drying system and using it to produce 800 kilowatts of electricity for the mill.

The system, designed and constructed by Illinois-based KGRA Energy, will be installed in the lumber mill’s energy area, near three large biomass boilers that heat thermal oil for the mill’s drying system, according to Jason Gold, KGRA CEO. The heat will be recovered from a kiln where cut lumber enters the drying process. “We are tapping into that thermal oil loop,” he explained, adding that the temperature runs just below 500 degrees Fahrenheit. “We are diverting some of that oil into our system and returning it back into their system after taking some of the energy out of that loop, and we’re making electricity with it.”

Weyerhaeuser will lease the system, self-produce the electricity and use it all on-site, Gold said. The process will save the lumber mill money on electric bills; reduce pollutants on-site; and create several local jobs during installation, Gold said. Beginning in June, that installation is expedited by the fact that KGRA’s systems are modular and designed for rapid installation with minimal impact to the customers’ own systems. “We do everything we can to preassemble and effectively prefabricate everything about this so that our on-site installation is substantially minimized,” Gold said.

KGRA Energy’s system is designed to recover waste heat from viable sources such as combustion engine exhausts, furnaces, boilers and kilns, converting it into electricity. Gold said the timber products industry holds a number of prime candidates for such as system, including pulp and paper mills.