焦炉煤气再燃降低NOx排放技术研究

焦炉煤气是炼焦工业的副产品,通常未得到有效利用.利用Chemkin软件柱塞流模型研究了利用焦炉煤气作为再燃气体脱硝的可行性.NOx脱除率主要受再燃区温度、氧气浓度、再燃燃料比等因素的影响.在适当的操作参数下,利用焦炉煤气再燃脱硝,NOx脱除率能达到60%以上,具有工业实用价值.焦炉煤气再燃脱硝会引起炉膛内局部还原性气氛增强、炉膛温度分布改变、燃烧效率下降等影响,需采取相应措施消除.

STUDY ON TECHNOLOGY OF NOx EMISSION REDUCTION BY COKE OVEN GAS REBURNING

Gas reburning is an effective technology to reduce the primary NO_x emission from coal-fired boiler,among which nature gas is most popular.Coke oven gas (COG), which is a byproduct of coke making,is often simply burnt in combustors as a regular fuel or even directly discharged into atmosphere.Numerical simulation was conducted on NO_x emission reduction by COG reburning,by using the plug flow model in CHEMKIN software.The effects of reaction temperature, oxygen concentration and the ratio of reburn fuel to the primary fuel on the conversion rate of NO_x were studied. It was found that when proper operational parameters were selected,the maximum NO_x conversion rate for this technology could be over 60%.The results indicated COG could be alternative reburn fuel for primary NO_x reduction in a boiler.Based on the numerical results,analysis was performed on the possible variations of combustion efficiency,temperature distribution in furnace and reducing atmosphere near the water wall in a coal-fired boiler as the COG reburning technology was applied.Some suggestions were given to overcome the negative effects for COG reburning.