Promoted reactivity of char in co-gasification of biomass and coal: synergies in the thermochemical process

A Review of Thermal Co-Conversion of Coal and Biomass/Waste

“…During co-firing of straw and coal, Pedersen et al [101] observed a net decrease of NO and SO x emission, due to the decrease of fuel-nitrogen conversion to NO and due to retention of sulfur in the ash. Sjöström et al [67] also identified a lower ammonia yield during co-gasification of birch wood and Daw Mill coal. Cordero et al [68] also showed enhancement in desulfurization when blending coal with different types of biomass during co-pyrolysis compared to coal pyrolysis.…”

“…This is in accordance with McKee et al [97] and Srivastava et al [98] who demonstrated the increased catalytic activity of alkali metals on gasification with increasing coal rank. The reaction rates of a blend of waste birch wood and Daw Mill coal was significantly increased and the char yields were lower than a simple blending prediction in a pressurized fluidized bed oxygen atmosphere gasifier with temperatures varying from 973 K to 1173 K at a pressure of 0.4 MPa [67]. Brown et al [96] came to the conclusion that switchgrass char and switchgrass ash displayed catalytic activity in mixtures with coal char produced from Illinois No.…”

“…The interaction between coal and biomass during thermal co-conversion is an issue yet to be solved; some devolatilization and pyrolysis results of coal and biomass blends have revealed no or very little synergy between the two fuels [44][45][46][47][48][49][50][51][52][53][54][55][56] while others have revealed significant synergy [43,[57][58][59][60][61][62][63][64][65][66][67][68][69][70][71]. It is important to segregate the synergistic effect from the catalytic effect engendered by biomass mineral matters; most of the studies that found synergistic effects between the two fuels failed to segregate these two phenomena.…”

“…However, the existence of non-catalytic synergistic effect remains controversial. Some researchers [43,[57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][101][102][103][104][105][106][107][108] have shown evidence of synergy between biomass and coal while others [44][45][46][47][48][49][50][51][52][53][54][55][56] found no evidence of synergy. Trevor and Kandiyoti [109] pointed out that the way biomass components are intermeshed affects the distribution of pyrolysis products.…”

Evaluation of Biomass and Coal Co-Gasification of Brazilian Feedstock Using a Chemical Equilibrium Model

“…The co-processing of coal-biomass blends can be carried out such that undesirable characteristics of one fuel can be compensated by desirable ones brought by the other. Some authors (Sjöström et al, 1999;Hernández et al, 2010;Xu et al, 2011;Song et al, 2013) have observed synergies using some combinations of these fuels. However, other authors (Collot et al, 1999;Zhu et al, 2008) reported the lack of interactions among fuels.…”