水溶钠对准东煤快速热解煤焦燃烧特性的影响

采用不同萃取液对准东五彩湾烟煤进行逐级萃取，分别利用电感耦合等离子体原子发射光谱仪和离子色谱仪对萃取制得的滤液进行相应的元素分析和阴离子检测。测试结果表明，准东煤中金属钠的赋存形态以水溶钠为主，且主要以NaCl，Na2SO4，NaNO3，NaHCO3等化学形态存在。在酸洗煤样中加载不同化学形态水溶钠，并在沉降炉快速热解条件下制备煤焦。热解煤焦的热重燃烧实验表明，添加水溶钠使煤焦的燃烧初始反应温度、着火温度和燃尽温度都较酸洗煤煤焦有所降低，表明水溶钠盐对高钠煤煤焦的燃烧具有促进作用。不同化学形态水溶钠的催化作用不同，以Na2CO3的作用最为显著。通过积分法计算得到了5种快速热解煤焦燃烧的活化能，加载水溶钠盐使煤焦燃烧的活化能降低，不同化学形态水溶钠的影响不同。

Effect of water-soluble sodium on combustion characteristics of Zhundongrapidly pyrolyzed coal char

The occurrence modes of sodium in Zhundong Wucaiwan bituminous coal were studied by the extraction with distilled water,ammonium acetate and hydrochloric acid step by step.Elements and anions in the extraction liquids were determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and ion chromatography (IC) respectively.The results show that the predominant occurrence mode of sodium in Zhundong coal is water-soluble sodium,which is mainly in the chemical forms of NaCl,Na2SO4,NaNO3 and NaHCO3.Through adding different chemical forms of water-soluble sodium to the acid washed coal and then fast heating to generate char in Drop Tube Furnace (DTF),the authors studied the effect of single chemical form of sodium salt on char’s combustion characteristics in a thermogravimetric analyzer (TGA).Results demonstrate that,compared to the acid washed coal,the chars made from coals loaded with whichever form of water-soluble sodium have a lower initial reaction temperature,ignition temperature and burnout temperature of combustion.It indicates that water-soluble sodium promotes the combustion of high-sodium coals.Catalysis of different chemical forms of water-soluble sodium differs,among which Na2CO3 shows most effective.Activation energy of char combustion was calculated by the method of Coats-Redfern.The loading of water-soluble sodium decreases the activation energy of char combustion,while the extent varies with the form of water-soluble sodium.