The use of biomass as carbon-neutral fuel for power generation has been increasing rapidly to displace the fossil fuels. It also has advantages of diversifying the fuel portfolio in a power plant and of reducing SO2 and NOx emissions. One common method for using biomass is to cofire in existing boilers. It can be achieve by direct co-firing the biomass and coal blend or by indirect co-firing after conversion of biomass into synthetic gas (syngas) using a separate gasifier. NOx is one of the main gas-phase pollutants released by oxidation of fuel-bound N and N2. For solid fuels such as coal and biomass, the fuel NOx formation is dominant over that for the thermal NOx. Although NOx released from the furnace can be removed by flue gas cleaning, it is required to minimize the NOx formation during combustion for lower operational costs. Reburning is one of technologies for in-furnace de-NOx, which can be applied to various systems with low capital/operational costs. The reburn fuel supplied immediately downstream of the combustion zone establishes a fuel-rich region for reduction of NOx to N2. The present study aims to investigate the contribution of syngas to reducing NOx emission by indirect co-firing with fossil fuels. For this purpose, various biomass types and simulated syngas were tested in a bench-scale furnace using coal as the main fuel. The effects of key combustible species in the syngas (CO, H2, CH4, etc) and various biomass on NOx reductions were evaluated quantitatively based on detailed measurement within the furnaces.
1. 서 론
2. 실 험
3. 실험 결과
4. 결 론