NaClO_2海水溶液强化烟气脱硝效果的实验研究

Study on the enhancement NO_x removal from simulated flue gas by NaClO_2 solution

海水中富含多种盐类,具有一定碱性,是天然的缓冲剂,在脱硫脱硝方面具有良好的应用前景.利用不同浓度的NaClO_2溶液进行废气循环喷淋脱硝实验.结果表明,NaClO_2模拟海水溶液与NaClO_2淡水溶液都能将NO完全脱除,且当NO完全被脱除时,模拟海水溶液的持续时间比淡水溶液更长,模拟海水中所含有的少量HCO_3^-和OH^-是造成这种差异的主要原因.滴定实验结果显示0.066 mmol的HCl就可使NaClO_2淡水溶液的pH值降到7,而NaClO_2模拟海水溶液的pH值降到7需要0.114 mmol的HCl;在循环喷淋脱硝过程中NaClO_2模拟海水溶液的pH值基本维持在7以上.离子色谱检测结果显示脱硝后溶液中主要阴离子为Cl^-和NO_3^-.基于质量平衡计算结果,当NaClO_2浓度为20 mmol·L^(-1)时,在脱硝过程中淡水溶液中NaClO_2的利用率为56%,而模拟海水溶液中NaClO_2的利用率可达67.25%,提高幅度为20.1%.

Seawater is a natural buffering solution because it contains a large number of salts and moderate alkalinity.So it has great potential in the applications of desulfurization and denitration.Experiments were conducted to investigate the NO removal from simulated flue gas by NaClO2 solution in a lab-scale scrubbing reactor.The results show that the NO removal efficiency of both NaClO2 simulated seawater and freshwater would increase to 100%,but the breakthrough time of NaClO2 simulated seawater lasted significantly longer than that of freshwater,which could be ascribed to the buffering capability of HCO3^- and OH^- ion in simulated seawater.The results of titration experiment show that the pH of NaClO2 freshwater quickly decreased to 7 after adding 0.066 mmol HCl.However,0.114 mmol HCl was required for NaClO2 simulated seawater to reach the neutral pH.The pH of NaClO2 simulated seawater solution was almost kept above 7 during the whole cyclic scrubbing process.The analysis of reaction products by ion chromatography indicated that the main anions in the spent liquor after scrubbing were Cl^- and NO3^-.According to the mass balance calculation,when the NaClO2 concentration was 20 mmol·L-1,the NaClO2 utilization rate was 56% in freshwater solution,while it could reach up to 67.25% in simulated seawater solution,resulting in an increase by 20.1%.