Final Report for FNE10-684
Our Goal was to build a flame weeder that uses waste vegetable oil to kill seedlings to prepare a clean bed to grow our baby lettuce crop. Our initial plan was to use Babbington Ball burner technology to sterilize the seed bed. We were seeking to use the Babbington ball burner inorder to use waste oil to fuel the flame weeder. After many attempts, our conclusion is that waste vegetable oil does not make a practical fuel in providing weed control. The Babbington ball design is not suitable for a mobile application and instead is more suitable for stationary burners. Our conclusion is waste oil is better used as a farm as tractor fuel, burned in stationary burners or for conversion to biodiesel fuel.
As an organic vegetable farm, having wet, cloudy weather makes it difficult to adequately control weeds. We use a combination of heavy cover cropping with fall planted rye/vetch and summer buckwheat and fallow cultivation to combat weeds. We create sterile beds prior to seeding our primary crop, baby lettuce, using tillage. However, this method is only effective when there are ample sunny days to kill weeds and dry out the bed to create a dust mulch. We have explored propane flame weeding to accomplish the same sterile bed technique but wanted to try waste vegetable oil as a more sustainable alternative to propane.
In this project we tried to use waste vegetable oil as a fuel source for flame weeding. The control of weeds is a problem common to most farmers and we would like to explore improving upon the technique of flame weeding by utilizing a sustainable, renewable fuel source.
The technology to burn straight vegetable oil is available and we attempted to adapt that technology to be used in the flame weeder application. This project involved building a tractor mounted flame weeder that will operate on waste vegetable oil (used fryer grease) as a fuel. We intend to use the waste oil flame weeder to help eliminate weeds in the seed beds of our NOFA NY certified lettuce farm.
The project uses the proven weed control technique of flaming and combines it with technology that allows for the use of waste vegetable oil as a fuel. We built a flame weeder that uses a Babbington Ball nozzle that will allow for the use of waste oils. Traditional oil burner nozzles tend to foul when using waste oil. The Babbington burner does not force oil thru a nozzle, rather compressed air is forced thru an orifice while waste oil flows over the stream of compressed air resulting in the atomization of the fuel.
A three point hitch mounted burner was constructed that has a compressor pump to create pressurized air and a waste oil pump to circulate waste oil to the Babbington nozzles. Five nozzles were mounted on a tool bar that allows the burners to be adjusted for bed crops like our baby lettuce or row crops such as kale.
The project uses a sustainable fuel source to reduce the negative impacts of tillage on soil structure and will hopefully increase the productivity of our farm by reducing weed pressure and speeding harvest.
Our main objective was to see if we could use the babbington ball burners to use waste vegetable oil as a fuel for a flame weeder. Our first target was to see if we could get consistant burning from the babbington balls. That we accomplished. While the unit was stationary, a flow of waste oil over the ball was steady and consistant and the resulting burn was clean.
Our second goal was to use the burner while the unit was in motion, attached to the three point hitch of the tractor. While moving, enen the smallest bounce or ou even ground would prevent the laminar flow of the oil over the balls and the balls ould go out. It was this sensitiv to bouncing at all that make the babbington ball less that ideal for a moving unit.
When we learned how sensitive the movement were that caused the flame to go out, we bagan to look at alternative designs.
We used a series of Babbington ball attached to a tractor mounted tool bar, Oil flows over the ball and compressed air in injected into the back of the ball and out three tiny holes in the front of the ball over which the oil flow. this oil is atomized by the force air and create a flamanble mist. The oil can not plug any hole because it is not being force through any smalll orfices, rather it flow over the small hole and any oil that is not atomized and burned simply flows off the bottom of th ball and is caught and recirculated for another flow over the ball.
Our conclusion is that many small farmers have access to used fryer grease when making deliveries to resturant kitchens. This oil is a good fuel for heating applications using a babbington burner. However, our attempt to use the fuel to fire a flame weeder proved to be impractical because Babbington burners do not work well while vibrating around on uneven ground. The oil flow was disrupted when bumped by driving over uneven ground and the flames would go out. The laminar flow of oil over the ball is required to produce a good burn and the ball in motion disrupts this flow.
Our accomplishments were getting a consistent flame out of the Babbington ball while stationary. This is a very usefule way to burn uncleaned or processed waste oil stright from the fryer. Many small farms that deliver products straight to resturant kitchens have access to used fryer oil. This oil can be burned straight, with minimal filtering, in a Babbington burner. Such a unit would be good for heating a farm shop or green house.
Education & Outreach Activities and Participation Summary
Annie Bass wrote an article that was published in the Small Farms issue of Country Folks. This article generated a lot of interest in the project and we got several calls and many phone calls about how it works. However, our conclusion after trying to make the burner work in several diffent set ups is that flame weeding is not a procatical use of waste oil using the babbington burner of standard oil burners. Propane, the traditional fuel used in flame weeders is the more appropriate fuel for flame weeding and wast oil may be better well used in dielsel engines of stationary heating units.
The use of waste vegetable oil as a fuel using a babbington burner is a good option for many small farms. Making Biodiesel out of waste vegetable oil is a common practice, but the process is not inexpensive when figuring the chemical costs and equipment. A Babbington ball burner can burn straight waste vegetable oil with minimal filtering and can be used to heat farm greenhouses or shops.
Waste vegetable oil is often available to farmers own direct market to resturants. This oil can be used to run farm tractors as straight waste vegetable oil or can be converted to biodiesel. We were seeking to use the waste oil to fual a flame weeder. After many attempts, our conclusion is that waste vegetable oil does not make a practical fuel in providing weed control. The babbington ball design is not suitable for a mobile application and instead is more suitable for stationary burners for for convertion to biodiesel fuel. A babbington ball burner is very suitable for stationanry heating.