Investigations On Denitration Through Reburning Of Biomass Gas

As one of the most important air pollutants, NO_x has drawn wide attention of the world because of its high hazard and hard treatment. Reburning technology is one of the most promising methods to reduce NO_x emission for its economy and efficiency. As reburning fuels, biomass and natural gas are almost matched in NO_x reduction. Using biomass and reburning with biomass gas instead of fossil fuels can not only remove NO_x efficiently but also ease the energy crisis in a certain extent for its renewability. Further more, for the lower N and S contents in biomass, reburning with biomass gas can greatly decrease the emission of NO_x and SO_x from fuel, and the net emission of CO2 is zero. At the point of this, as a kind of reburning fuel, biomass is of great positive environmental significance. Obviously, this is a quite promising research.In the first chapter, the background and research state were discussed. The important significance of combining the energy crisis and environment pollution was indicated. Then basic property of biomass, pyrolysis character and the composition of biomass gas were studied respectively. In this way, the production process and the components of biomass gas and the influence factors were mastered. Based on the master of biomass gas, a serial of experimental and theoretical researches of NO_x reduction with biomass gas as reburning fuel were carried out. All experiments were carried out on the small-scale test facility self-designed and manufactured. All gases used in experiments were simulated gases. The NO_x reduction efficiency was calculated by measuring the concentration of NO in the inlet and outlet of reactor. The results suggested that in the range of 800-1200℃, the NO_x reduction efficiency increased with the increasing of reburning temperature and residence time. But with the increasing of initial NO concentration, SO₂ concentration and moisture, NO_x reduction decreased. And NO_x reduction efficiency increased firstly and the decreased while the equivalence ratio increasing, and at the point of 1.15 the NO_x reduction efficiency reached the maximum. Lastly, a model was developed on the base of experiments and numerical simulation for the reburning process was carried out utilizing the software CHEMKIN. The results showed that the model could well predict the reburning process.