Scientists of Tomsk Polytechnic University have discovered that fusible wheat bran combined with additives can be used as fuel. It could help to reduce greenhouse gases and the number of landfills, as well as to optimize the creation of mixtures for the efficient energy use of biomass. The research findings are published in the Fuel academic journal.
According to the TPU scientists, various types of biomass, such as agricultural waste, have been increasingly used as fuel in recent years. They conducted research where they examined wheat bran from one of the flour mills in the Siberian region of Russia.
The researchers discovered that bran is a fusible fuel. The mineral part of wheat bran is already sintered at a temperature above 675°С, which is much lower than the temperature in the boiler. During combustion, the biomass under investigation forms a glasslike deposit of slag ash, removing that it is possible to damage the heating surface. As a result, it will reduce the heat transfer, reliability of operation and boiler output.
According to the scientists, wheat bran contains a lot of potassium. It strongly influences the melting point of the mass and the formation of a glasslike deposit. To investigate the mineral content of wheat bran in more detail, the wheat bran was divided into fractions of different densities by sedimentation (the settling of particles in a liquid or gas under the action of a gravitational field or centrifugal force). The scientists obtained four fractions, two of which form a crumbly mass when combusted.
“Having studied the mineral composition of the obtained fractions, we found that the key factor influencing the sintering of bran ash is the ratio of calcium to high potassium content. To confirm it, we conducted experiments by adding calcium carbonate to the bran, which resulted in crumbly and powderlike ash residue. It evidences that the combustion of this mixture results in the cleaning of heating surfaces without much difficulty,” Kanipa Ibraeva, Engineer of the TPU Butakov Research Centre, told Sputnik news agency.
There are several approaches to prevent the sintering of ash during biomass combustion, the researchers noted. They mainly include the addition of additives that can raise the melting temperature.
“To select an additive with active chemical composition and an economically attractive cost is quite difficult. We believe that combustion of fusible biomass with the addition of calcium carbonate will reduce operating costs,” Ibraeva commented.
Moreover, the experts claim that fuel from various types of biomass will allow reducing greenhouse gases from combustion, as well as will reduce the number of landfills and recycle industrial waste.
The research team is currently planning to conduct comprehensive research of the mineral part of the biomass and examine the effects of volatile ash compounds on accelerated corrosion of the metal surfaces of power plants.