【作者】 林晓珍；

【导师】 陆晓华；

【作者基本信息】 华中科技大学 ， 化学工程， 2011， 硕士

【摘要】 煤燃烧过程中污染物的排放已成为全球关注的热点问题,特别是燃烧过程中排放的汞、NO和SO₂对人类的健康带来了巨大的危害。有关煤燃烧汞排放控制的研究是当今国际前沿课题,为了减少煤燃烧过程中污染物的排放,寻求一种同时脱除汞、NO和SO₂的方法具有重要的意义。煤燃烧过程中汞的不同形态对于其脱除具有重要的影响。为了促进燃烧过程中单质汞的氧化及减少NO和SO₂的排放,本文选取六枝煤、六盘水煤和高平煤,添加溴化物在实验室小型管式炉台架上进行了混烧实验。研究了溴化物种类、添加比例、温度和煤种对煤燃烧过程汞形态转化的影响。此外,考察了这些因素对NO、SO₂排放的影响,以揭示添加溴化物对多污染物联合脱除的影响规律。实验结果表明,添加溴化物对各种燃煤烟气中的汞有一定的氧化作用,煤种不同氧化效果不一样。总体看来,溴化钙的氧化效果比溴化钠好。反应温度是影响汞挥发和形态分布的重要因素。较大的添加比例在较低的温度下效果较好,因为低温下生成的HgX2分解的量较少。从三种溴化物对烟气中NO还原来看,三种添加剂均有利于NO的还原,且NO的生成过程和生成总量都发生了变化。反应温度是影响NO还原的重要因素,相同的煤种在不同的温度下NO的排放特性不一样。在相同的实验温度下,溴化物的添加都取得比单独的煤粉燃烧更好的脱硝效果,在较低温度（800-900℃）下其效果更为明显。从三种溴化物对抑制SO₂排放的影响来看,效果最好的是溴化铵,其次是溴化钙,最后是溴化钠。高温下的抑制效果比低温要好,较大添加比例有利于减少SO₂的排放。此外,还研究了基于汞吸附管的烟气汞的取样分析方法。从汞吸附管达到最大吸附量来考虑,烟气温度为120℃和烟气中SO₂的浓度低于1000 ppm时有利于汞吸附管对烟气中汞的吸附。更多还原

【Abstract】 The emission of pollutants during coal combustion process has become a hot issue of global interest, especially the emission of mercury, NO and SO₂ have caused great harm to human’s health. And the relative researches about the emission and control of the mercury during coal combustion is recently an active topic. In order to reduce the emisson of the pollutants, it is necessary to find a method that can remove mercury, NO and SO₂ at the same time.The bromine compounds additives were chosen to promote mercury oxidation and decrease the emission of NO and SO₂. The experiments were carried on laboratory horizontal tube furnace, Liuzhi, Liupanshui and Gaoping coal were chosen to investigate mercury species transformations and NO, SO₂ reduction in coal flue gas when co-combusting bromine compounds with three kinds of coal. We considered four factors such as, combustion temperature, different bromine compound, the mass of bromine compound and the type of the coal to study mercury species transformations and NO, SO₂ emissions during the combustion process. So we can get the results that how bromine compounds effect mercury species transformations and NO, SO₂ emissions.The experimental results show that bromine compounds additives can partly enhance mercury oxidation during coal combustion. Different type of coal has different oxidantion effect. Overall, the oxidation of calcium brominate is better than brominate sodium. The combustion temperture is an important factor that can affect mercury volatile and species. Under low temperature the oxidation effect is better at larger addition proportion, because HgX2 decompose under high temperture. But at higher additive ratio, it will cause some degree of corrosion.Adding three kinds of bromine compounds are conducive to the reduction of nitric oxide （NO）, and both NO generative process and the total amount of NO have changed. NO reduction was influenced by the combustion temperture. The same kind of coal under different temperture, NO emission characteristics were different. Cofiring coal with bromine compounds at the same temperture all resulted a better denitrification effect compared to firing the coal alone, and the effect is better when cofiring at lower temperture.Considering adding bromine compounds to restrain the emission of SO₂, ammonium brominate is the best, and then calcium brominate, sodium brominate comes last. Inhibition effect is better at high temperature, larger adding ratio also helped to reduce SO₂ emissions.In addition,We also studied a method based on mercury adsorption tube in flue gas. To make the sorbent trap achieving maximum adsorption capacity, the temperature of the flue gas should be 120℃and SO₂ concentration should below 1000 ppm.更多还原