Scientists at Tomsk Polytechnic University (TPU) have improved the properties of available biofuels. According to the authors, they could obtain environmentally friendly fuel from peat and bran, which is comparable in its characteristics to brown coal. The study was published in the journal Fuel.
The use of fossil fuels is a promising area of alternative energetics, which significantly reduces the negative impact on the environment and provides cost-effective disposal alternatives for industrial organic waste.
Separation by sedimentation is a method to improve the quality of fossil fuel by removing mineral impurities. TPU scientists used this method to improve the properties of available types of biomass, as well as for detailed X-ray examination of the mineral components.
In a centrifuge, under centrifugal force, mineralised biomass, including high-ash peat or bran, was separated into two fractions – a heavy peat fraction with a high content of minerals, and a low-ash peat fraction, close to purely organic.
The authors reported that in terms of combustion efficiency, the fuel obtained by this method is comparable to brown coal, which is widely used in heating plants and thermal power plants.
“The mineral part of peat and bran causes significant difficulties during combustion. The dried peat ash-content is over 20%, which seriously decreases its combustion heat and reduces the efficiency of heating plants. The ash residue from bran combustion sinters, thus forming strong slag deposits that impair heat transfer and reduce the efficiency and operating life of boiler equipment”, Roman Tabakaev, a researcher at the Butakov Research Centre at the TPU School of Energy and Power Engineering, said.
According to TPU scientists, the highly mineralised biomass fraction that sinks during separation by sedimentation can be used to obtain highly efficient carbon sorbents for water purification.
A key factor in the heavy peat fraction sintering was found to be a high content of potassium in relation to calcium. The peat and bran composite fuel will completely prevent the formation of strong slag deposits.
“The addition of at least 5% of CaCO3 during bran combustion completely prevents ash residue from sintering. The same can be achieved by adding fuel with calcite content, for example, high-ash peat”, Roman Tabakaev explained.
The study was carried out together with the Boreskov Institute of Catalysis SB RAS. In the future, the research team wants to continue studying the biomass mineral components to develop new types of fuel and improve the technology to produce carbon sorbents.