Scientific Research On Control Technology Of Syngas Reburning

With the rapid growth of the global economy, the fossil energy’s massive mining and utilization cause the air pollution and the ecological environment destruction. Major consumption of energy in china is coal, which currently accounts for about70%of china’s energy and still dominates in energy production and total quantity consumed in a long period of time in future. Thermal power plants are large consumers of coal resources, but also a major source of pollutant emissions, which mainly include CO2, SO2, NOx, dust and heavy metals (Hg, As, Pb, Cd, etc.) pollutants to human health and the environment caused great impact. Especially NOx gases and heavy metal Hg are the major air pollutants which are harm the largest and the hardest to manage. With the improvement of our country for a variety of pollutants discharge control requirements, especially NOx gases and heavy metal Hg, to take effective measures to control NOx and Hg emissions in the process of coal combustion is a very urgent task at present. Reburn (Reburning) technology is considered to be one of the most economical and most application technology in numerous NOx emission control technology. Therefore, this article uses synthesis gas as reburning fuel, study the characteristics of syngas reburning reduction NOx and reburning process on the influence to form of the migration of heavy metals of mercury in flue gas on drop tube furnace.This paper introduces the background and research significance of syngas reburning from the start, systematic summary and describes the main fuel reburning technology at home and abroad. Experimental study of various kinds of key factors in the gas fuel reburning process; Then details the different gaseous fuels reburn NOx formation and reduction mechanism, the mechanism of methane reburn process migration and transformation of mercury species. Master the mechanism of internal relations contribute to study on the analysis of experimental results. Secondly, introduced the structure of the experiment system and its working principle, at the same time prepared enough pulverized coal. Finally, according to the design requirements, carry on the system test. Experiment studies were performed on influences of NO removal efficiency by different hydrocarbon ratio syngas, reburning zone excess air coefficient, reburning zone temperature, reburning zone residence time, reburning fuel fraction, burner nozzle, acoustic wave. Meanwhile, the influence of formation distribution of mercury and the burn-off rate of the pulverized coal during recombustion of gas fuel.Experimental studies on gaseous fuel reburning process have been performed in a drop tube furnace. The influences of different hydrocarbon ratio syngas, reburning zone excess air coefficient, reburning zone temperature, reburning zone residence time, reburning fuel quantity, burner nozzle, acoustic wave were also quantitatively analyzed. According to the experimental results, NO removal efficiency of CH4is the most efficiency, H2is medium, CO is the lowest. NO reduction efficiency of syngas reburning behaves a trend of first increases and then decreases with increasing of hydrocarbon ratio, when hydrocarbon ratio increases to7/3denitration effect is best, but less than methane reburning effect. At the same time get the best value range of all kinds of key factors in the process of the syngas reburning. The higher NO reduction efficiency can be achieved under the optimizational reburn configurations. The optimized average excess air coefficient for reburn zone is about0.7-0.9. The reasonable temperature of reburn zone is about1200℃. The reasonable residence time of reburn zone is about0.6s～0.9s. The appropriate amount of gaseous reburn fuel is about15%～20%of the total thermal input. The top of the reburning gas pipe and the burnout duct were installed atomization nozzle. Based on the above experimental conditions, the combustion reaction zone passed through a strong sound wave, denitrification efficiencies increased about10%, to reduce the concentration of CO in flue gas is about50%. Finally, through different gas reburning fuel reburning process found that methane can effectively gaseous elemental mercury in flue gas oxidation into bivalent mercury, increase the absolute content of bivalent mercury in flue gas. But the syngas is bad for converting elemental mercury into bivalent mercury, improve the absolute content of elemental mercury in flue gas.