Bale Burner Built From Railroad Car

Hiawatha, Kan., farmer Doug Grimm has a new way to put his wheat straw to work: he burns it in his big bale burner that heats his greenhouses and a couple of other farm buildings.

Grimm converted an old railroad tank car to burn big round bales of wheat straw. Air pipes transfer heat to water which is then pumped through in-floor heating systems and radiators.

"We've used it for three years. In the coldest weather it saves us in energy costs," says Grimm, who grows a corn, beans, and wheat rotation and also runs a greenhouse operation where he grows tomatoes, strawberries, and flowers. "We had been using propane to heat the buildings, but it got too expensive. Now we use only the bale burner to supply the buildings with heat."

He paid for a 26-ft. long, 10-ft. dia. section that had been cut off a 60-ft. rail-road tank car. One end of the tank was closed. A local blacksmith welded a steel divider inside the tank to separate it into a 16-ft. fire chamber and a 10-ft. long water tank. The water tank holds 3,000 gal.

Water is heated to about 180 degrees through a series of air pipes that runs from the fire chamber through the water tank. The pipes run to a steel box that's welded to the end of the tank. An exhaust stack equipped with a small fan and motor is used to pull air through the pipes.

Thermostatic-controlled pumps inside the greenhouses circulate hot water through copper pipes buried under the floors of the buildings. Cooled water from the buildings then returns through 1 1/2-in. dia. insulated pipe. The pipe runs through a steel jacket welded on top of the burner area. Water is heated as it flows through the steel jacket and back into the water tank.

The fire chamber is equipped with a pair of 1/2-in. thick steel "water jacket" doors with a 3/4-in. layer of water inside them. "Water flows through the doors to keep them from warping under the intense heat," explains Grimm. A small electric pump takes water from the bottom of the water tank, where it's the coolest, and pumps it through pipes that run down along each side to the doors. The pipes are plumbed into the bottom of each door. Another pipe at the top of each door carries water back to the tank.

Fresh air inlets in the bale burning chamber keep the fire burning hot and clean. A length of 3-in. sq. steel tubing runs down along each side of the tank and along the back wall to provide fresh air. Holes drilled into the tubing allow the air to be injected right before heated air goes into the air pipes.

"It works good. I built it because I couldn't find anything on the market that was affordable and could do the job I wanted," says Grimm. "I load bales into the burner with a front-end loader. The burner is big enough to hold up to round 3 bales at once, but I burn only one bale at a time. It takes about a day to burn an entire bale. Burning straw heats the water to only about 140 degrees, and when it's real cold outside it takes 180-degree water to keep the greenhouses warm. So during the winter I also burn scrap wood which causes the fire to burn hotter. I get the wood from a local manufacturer."