Inhibition of coal-fired condensable particulate matter by addition of biomass

Effect of Torrefaction on Aerosol Emissions at Combustion Temperatures Relevant for Domestic Burning and Power Generation

“…On the other hand, coal emissions had a larger fraction of SVOC, which is expected to be emitted in the gas phase and condense and form particles upon cooling of the emissions. This result further supports our assertion that in this study, coal aerosol emissions at 1000 °C fall under the definition of CPM …”

“…This trend indicates that the combustion efficiency of these fuels increased with increasing temperature, thus reducing the emissions of partially oxidized species, including aerosols. An important practical implication of this finding is that utilizing these biomass fuels in power generation applications, where the combustion temperatures are relatively high, ,,, is expected to produce low aerosol emissions. On the other hand, biomass combustion in domestic settings, where starting and burnout temperatures are relatively low, leads to high levels of aerosol emissions, as previously reported in various domestic burning studies. − …”

“…The combustion experiments were performed using a steady-flow reactor at an air-to-fuel ratio of 25 and at combustion temperatures of 400, 600, 800, and 1000 °C. This temperature range was chosen to encompass the temperatures encountered at different stages in domestic combustion, and the higher temperatures (800 and 1000 °C) overlap with those in previous studies that simulated power generation combustion conditions. ,, The fuel particles were supplied into a combustion reactor at a controlled mass flow rate in a fashion similar to the drop-tube furnace or one-dimensional furnace configurations commonly employed in pulverized coal and biomass combustion studies. − We utilized a custom-built particle-feeder system based on the design of Molinder and Wiinikka . The particle-feeder system consists of a vertically mounted glass hopper attached to a syringe pump pusher block.…”

“…While replacing coal with biomass, including torrefied biomass, has a climate benefit due to the reduction in greenhouse gas emissions, the impact on emissions of air pollutants, including aerosols (or particulate matter, PM), is less clear. The combustion of both coal and biomass produces high concentrations of aerosol emissions, not only in low-efficiency domestic burning, − but also in industrial processes. , Due to their significant public health impacts, , emissions from domestic cookstoves have been extensively studied. Aerosolspecifically PM with sizes smaller than 2.5 μm (PM 2.5 )emission factors from cookstoves reported in the literature range over 3 orders of magnitude from 10 –1 g/kg-fuel to 10 2 g/kg-fuel. − With biomass and coal having heating values on the order of 10 1 MJ/kg, , the range of emission factors per unit energy translates to 10 –2 –10 1 g/MJ.…”

“…Aerosols emitted from domestic combustion are dominated by carbonaceous species, including elemental carbon (EC) and organic carbon (OC). ,, On the other hand, due to the more complete combustion conditions in power generation applications, the carbon in the fuel is more efficiently converted to CO 2 . Under such conditions, the aerosol emissions are often dominated by inorganic species, , and their formation potential is correlated with the ash content of the fuel . Torrefied biomass fuels usually have higher ash content than their raw counterparts .…”