shows the variation in the biomass
feeding rates with the variation in f. At f¼ 0, no supplementary
firing is employed and the plant solely depends on wood gasified in
the gasifier. Under this condition the wood firing rate is found to be
24.7 tph (tonne per hour). As f increases, the feed rate of the second
biomass (i.e. bagasse) fired in the supplementary firing chamber
increases and the dependence of the plant on wood decreases. At
f¼ 0.5, the feed rate of the wood is reduced to 18.5 tph (25%reduction compared to f ¼ 0 case), while the bagasse feed rate is
5.87 tph. One important limitation of operating a high power BIGCC
plant is the availability of biomass as the cost of generation largely
depends on this factor. As different biomasses are spread over large
distances, the transportation cost of a single biomass from
a distance contributes to a steep rise in the cost of generation.
When supplementary firing is employed, the dependence on
a single biomass reduces. This avoids the transportation of a single
biomass from a large distance to cater the need of the plant. Instead,
two different biomasses (like wood and bagasse in this case)
available in the nearby region can be employed for the plant
operation. This reduces the transportation cost of biomass and
saves the logistic requirement to a great extent. Moreover, the total
mass flow rate through the GT system reduces, due to the reduction
in both the air and fuel flows, when supplementary firing is
employed. This helps in keeping the operating point away from the
surge limit of compressor.