Co-firing carbon dioxide-torrefied woody biomass with coal on emission characteristics

Abstract

Torrefaction is a pre-treatment technique that involves the partial pyrolysis (200-300°C) of biomass in an inert environment to improve its fuel properties. Effect of co-firing CO 2 -torrefied mesquite and juniper (10 % on mass basis) with coal in a 30-kWt downfired burner was studied considering the grindability potential of CO 2 -torrefied biomass (60 % higher grindability than N 2 -torrefied biomass). It was observed that co-firing 10 % by mass of raw mesquite with coal reduced the NO x emission from 420 to 280 ppm (33 % reduction) for an equivalence ratio (ER) of 0.9. However, co-firing TB with coal reduced the NO x emission by 10 % when compared to base case NO x emission from combustion of pure powder river basin coal (PRB) coal. Carbon monoxide percentage in the flue gas increased when biomass was co-fired with coal. An inverse relation was observed between CO and NO x emissions due to NO x reducing potential of CO in the presence of fixed carbon. Combining the advantages of using a greenhouse gas CO 2 for pretreatment and potential of CO 2 -torrefied biomass in reducing emissions with improved grindability, proves co-firing torrefied biomass with coal is an efficient technique.

Experimental study of the combustion and NO emission behaviors during cofiring coal and biomass in O2/N2 and O2/H2O

“…The volatiles released during biomass pyrolysis contain amounts of reducing gases, which are conducive to NO reduction. A higher CO concentration produced during co‐combustion also contributes to NO reduction . At a higher CO concentration, the reduction of NO over char is accelerated via the char/NO/CO heterogeneous reactions: where C(O) denotes a chemisorbed surface oxygen and C f denotes an active carbon site.…”

“…Co‐combustion offers lower NOx emission, and NOx emission decreases with increasing biomass blending ratio . High CO emission during co‐combustion contributes to the decrease of NOx emission . Moreover, there is an interactive effect of co‐combustion on NOx emission in air and O 2 /CO 2 combustion .…”

Effect of Torrefaction on the Physiochemical Characteristics and Pyrolysis of the Corn Stalk

“…Therefore, many nations are intensively dedicated to studies of renewable energy resources to alleviate the dependence on fossil fuels [3][4][5]. Lignocellulose biomass is a significant resource for the production of fuels due to various advantages of lignocellulose biomass, including zero carbon emission, extensive availability, improved stability, and safety [6][7][8]. However, raw lignocellulose biomass has the drawbacks of high moisture content, high oxygen content, and complex variations in chemical composition [8][9][10][11].…”

Effect of rice husk and petroleum coke blending on combustion characteristics of high ash Indian coals

“…Behera et al [1] observed that high ash coal has inferior burning profile and GCV compare to low VM coal. To reduce the impact of ash layer formed during combustion, improving VM and gross calorific value (GCV), scientists recommended blending high ash coal with high VM coal, biomass or similar feedstock [6][7][8]. Sung et al [9] and Singh et al [10] reported that biomass has better ignition and combustion properties than coal due to the presence of higher VM and highly reactive hydrocarbons.…”