DAEGU — At the Ajin P&P paper mill in Dalseong County, Daegu, on the 19th, hot steam pouring from a massive dryer filled the air the moment the plant's steel door opened. The temperature inside approached 40 degrees Celsius, and standing beside the equipment for less than 30 seconds was enough to leave a sweat-soaked back.
In the middle of the haze crouched a huge dark gray cylindrical steel unit, resembling a submarine hauled up from the deep sea. It is an industrial heat pump from LG Electronics (066570), standing 3.8 meters tall and weighing 50 tons. It serves as the heart of an energy loop, drawing in the enormous waste heat that once escaped into the air during the baking and drying of paper and pushing it back into the production process.
The installation spans two floors and 600 square meters, from the piping that recovers waste heat to the heat exchanger on the roof. It is the first 1,000-refrigeration-ton high-temperature, large-capacity system to be demonstrated in South Korea. Installation began in June and system stabilization was completed in September, with demonstration operations set to continue through the end of next year.
Paper mills are among the most heat-intensive industrial sites. About 65% of their total energy use goes to thermal energy, and more than 30% of the heat put into drying paper escapes as steam. Kim Hee-young, a team leader at the Ajin P&P technology research institute, said complaints about white plumes around the plant were constant because of the discarded waste heat, and that eliminating them required pouring in even more energy, creating a vicious cycle.
That discarded heat becomes raw material for the heat pump. The technology relies on the same refrigerant-based heat transfer principle used in air conditioners and refrigerators, absorbing low-temperature heat and then raising its temperature with a compressor before discharging it. The new system recovers waste heat of about 60 degrees Celsius and produces hot water at 108 degrees.
Development proved as demanding as the machine's size. The project drew about 70 researchers and more than 30 billion won over five years as a government-funded national research initiative. Lee Ki-wook, a senior researcher at LG Electronics, said that because the product was an ultra-large unit weighing 50 tons, even a slight design error meant scrapping and remaking the entire mass of steel. The research team designed and assembled the system, including the compressor and inverter, in-house.
The plant expects annual energy cost savings of 2.5 billion won. Kim Jin-doo, co-chief executive of Ajin P&P, said running a single paper machine line costs about 20 billion won a year in energy, including liquefied natural gas fuel, and that recovering waste heat with the heat pump can save 2.5 billion won annually. That means an investment of about 10 billion won can be recouped in four years. Conventional boilers have an energy efficiency, or coefficient of performance, of about 0.9, while the new heat pump is expected to reach 2.9 — more than triple the heat output for the same energy input.
Another reason companies are turning to industrial heat pumps is the cost of carbon emissions. Cutting fossil fuel use can also ease the burden of buying emissions permits.
LG Electronics plans to use the demonstration as a springboard to expand into other industrial sites that require high-temperature heat. Lee Nam-soo, head of LG Electronics' ES advanced research team 3, said that after completing this demonstration, the company will broaden the range of industries it serves, including the use of waste heat from data centers, which give off enormous amounts of heat.
