Air curtain burners can reduce by 97 percent the volume of wood waste and other combustible materials by burning in an in-ground dirt trench or above ground firebox. A strong current of air forced over and through the burning materials helps greatly to reduce particulate matter emissions, including smoke and ash. While their main application, clearing land for real estate development, is slow right now, air curtain burners are finding new customers in storm debris cleanup, forestry, construction, landfills and transfer stations.

At Air Burners, LLC, in Palm City, Florida, Norbert Fuhrmann, director of sales and marketing, said the company’s in-ground trench burners and aboveground fireboxes are useful when there is a waste stream consisting primarily of clean wood waste. “Extraordinary uses, mostly by the government and military, include diseased carcass disposal and general waste disposal at overseas United States military installations, especially in the war theaters,” he said.

“Our equipment is affordable, has a long useful life of 12 to 15 years, is very simple to operate and has a very low operating cost – basically the cost of two to three gallons of diesel fuel per hour,” Fuhrmann said. The company makes a wide array of models, the most popular of which are the S-327 and S-220 Refractory Walled Air Curtain Burners. Both are above ground box burners shipped fully assembled. The S-327 employs an 85-h.p. Kubota or equivalent engine pushing air through a firebox measuring approximately 27 feet long by 8 feet high and 8 feet wide. The S-327 can process from 6 to 10 tons of waste per hour.

Air Burners’ latest model is a standard firebox coupled with an off-the-shelf electric power generating turbo-expander that can produce up to 350 kilowatts. Fuhrmann expects the Powergen Firebox to be Air Burner’s hottest seller. “Although some of our machines heat greenhouses or dry soil or wood, until now we could not offer a solution to convert the wood waste to electricity,” he said. “Now we have overcome that also.”

Regulation obstacles remain for the industry, however. “Our challenge is to demonstrate that our machines are much more cost efficient and more environmentally friendly than the debris disposal alternatives of chipping/grinding and hauling and dumping of the chips or wood waste in landfills or composting,” Fuhrmann said.

Nevertheless, Fuhrman said that beetle infestations calling for destruction of large volumes of diseased trees, wildfire management programs and availability of economic stimulus funds have helped forestry applications remain very active. “Market for the power generating versions will be power companies that are obliged to furnish power to communities remote from the grid and need to clean hydropower reservoirs, national parks in western states and landfills and transfer stations throughout the country,” he added.

At McPherson Systems, Inc. in Tifton, Georgia, president Don McPherson presides over the design and manufacture of permanent and portable pit, trench and box burners. McPherson said burners make debris clearing and other applications considerably more effective by reducing the volume of burnable waste by approximately 97 percent, using a proven, reliable technology. “There’s no big secret to it,” said McPherson. “It just puts a lot of air on the fire, into the fire and under the fire.”

McPherson’s 30-foot M30F Air Curtain Destructor is its most popular trench burner. It has a 110 h.p. Cummins engine spinning a fan that moves 40,000 cubic feet per minute. The company also builds the 40-foot M40F. McPherson’s most popular box burners are its M-15 and M20E models. The M30FRP Portable Refractory-Lined Pit is a larger unit transportable by semi-trailer.

McPherson started building burners in 1985 and became popular in the wake of the massive debris-clearing effort in South Florida following Hurricane Andrew in 1992. Since then, the company has come to rely on land clearing for real estate development. As that market has fallen, they have sold burners for cleanup after Midwestern tornadoes and to government contractors deploying them in locations such as Afghanistan and Kosovo for general waste disposal.

At Concept Products Corporation in Paoli, Pennsylvania, vice president Steve DiMascio said the appeal of his company’s air curtain trench burners rests on their ability to save money. “It’s the cheapest, most cost-effective way to dispose of land clearing debris off of job sites for new construction,” he said. “It’s the most cost effective way because you’re not hauling it away period. You have no trucking costs. Even if you grind, you still have to haul the product. With the air curtain you handle it once when you bring it over to the pit, and it’s gone.”

Concept Product’s most popular machine is its Air Curtain Destructor CP2000T. DiMascio said the CP2000T’s fan and manifold design produce greater airflow while consuming a smaller amount of horsepower. “In other words, it’s the most efficient running machine,” he said. The CP2000T pushes through 22,240 cubic feet of air per minute, employing a 33 h.p. diesel engine. That model is 20 feet long, and the company produces varying models up to 40 feet long.

While pollution controls are affecting sales, DiMascio notes trench burning is safer and produces fewer pollutants compared to alternatives such as open burning. “We’re burning much cleaner because we’re burning at higher temperatures,” he said. “When you’re burning at 2,000 degrees it burns much cleaner.”

Thus far, Concept Products has found tough sledding when seeking our new customers and applications. “With the restrictions on burning, it’s tough to branch out into other markets,” DiMascio said. “But it does a good job for what it’s designed for.”