Martinsville, Va.-Jimmy Branscome does not worry that his furnace will run out of fuel. The millions upon millions of scrap tires in the U.S. offer a steady, ample supply.
Mr. Branscome's company, Atlantic Pacific Energy Systems of Martinsville, Va., holds two patents on its rotary furnace, which burns whole tires at a rate of about two passenger car tires per minute or one highway truck tire every 72 seconds.
The tires do not require the expense of shredding. They are put onto a loading dock and travel via conveyor into the kiln, where they are burned in suspension, Mr. Branscome said.
``They are induced with hot air that is preheated by fire,'' he said. ``When our air goes into the firebox, it's around 1,200 degrees. This makes it burn faster and cleaner.''
Steam is produced from the tire-derived heat by means of a waste heat boiler downstream from the tire furnace, Mr. Branscome said.
``It works similar to a diesel truck,'' he said. ``If you took a five-gallon can of diesel fuel and burned it, you'd get a lot of black smoke. If you take a tire and set it on fire, it's the same thing. But if you put the diesel fuel into a truck and mix it with air, the truck goes down the road and doesn't smoke.''
Atlantic Pacific's unit is designed to burn just tires, while other operations mix the tires with coal and sawdust, Mr. Branscome said.
The furnace reduces a 20-pound passenger tire to 1 pound of ash in 30 seconds. Carbon black is combusted during the process, in which temperatures reach 2,300 degrees Fahrenheit, and even the wire is consumed in the heat, Mr. Branscome said. The resulting bottom and fly ash are taken to a nonhazardous landfill.
One pound of scrap tire rubber can produce 15,000 British thermal units. Producing 26,000 pounds of steam per hour with scrap tires generates $98 in income, according to Atlantic Pacific's calculations. Income can be generated from tipping fees and scrap tire credits from the government, as well as the sale of steam, which can be used for applications ranging from wastewater treatment to food processing. It would cost $79 using coal or $158 using natural gas to produce the same amount of steam.
Talks with several potential buyers are under way to build what would be the first whole tire furnace, Mr. Branscome said. His firm also has spoken with Michelin North America Inc. and Goodyear.
A Goodyear spokeswoman said the company has talked with Mr. Branscome's firm. She declined to comment on how or if Goodyear might pursue Atlantic Pacific's technology, but she said Goodyear is always looking for ways to improve its handling of scrap tires.
Mr. Branscome, who has been in the tire business since 1967, started on his furnace idea in 1990 under the theory that tires would burn cleanly and efficiently if burned in their own environment with preheated oxygen. He and his partner figured they could use the energy from tires to generate electricity, to dry sludge or to incinerate hazardous or medical waste.
The first rotary kiln that they designed to burn the tires turned out to be ``the world's largest flame thrower,'' Mr. Branscome said.
They modified the furnace and found that it was burning pretty cleanly, so Atlantic Pacific went to state regulators to get a test permit. The first test in the permitting process was bumpy-insulation fell off the rotary kiln and it only burned for four hours. Officials with the Virginia Department of Environmental Quality, who were watching the test, told Mr. Branscome not to give up. A second test in 1995 lasted six hours and prompted a few more modifications.
In November 1996, the furnace ran for 72 hours and passed the state's requirements. Since then, Atlantic Pacific has pursued its patents, receiving the first in 1999 and the second one earlier this year, Mr. Branscome said.
A plant built to generate steam would cost about $4 million and generate net income of $500,000 to $1 million annually, he said.