二氧化碳和水气氛对高钠煤转化过程中钠迁移的影响

摘要

The sodium release and transformation of Yili (YL) and Hutubi (HTB) coal were examined at different temperatures under N2, CO2and H2O atmospheres. By using sequential extraction and wet digestion separately,the occurrence mode and content of sodium in raw coal and chars were measured. The migration of sodium in two coals was studied qualitatively and quantitatively. The results show that water soluble sodium in YL coal accounts for 80.08%,while in HTB,insoluble sodium is 61.54%. The volatilization of sodium in two coals increases with increasing temperature. Water soluble sodium in semi coke shows a decrease trend;ammonium acetate soluble sodium increases and then decreases; hydrochloric acid soluble sodium exhibits an increasing tendency. For YL volatilization of sodium is inhibited by CO2while it is promoted by H2O compared with N2. At 900℃ volatilization of sodium under CO2and H2O is 50.25% and 111.45%,respectively,of that under N2. CO2atmosphere can inhibit volatilization of sodium in HTB. At 900℃ volatilized sodium under CO2 is 80.91% of that under N2. In H2O atmosphere,volatilization of sodium is higher than that in N2before 800℃and slightly lower than that in N2at 900 ℃. The predominant sodium in YL coal is water soluble which volatilized during increasing temperature and transformed to hydrochloric acid soluble and insoluble sodium simultaneously. While for HTB,insoluble sodium is the dominant occurrence mode, followed by water soluble one. CO2and H2O can promote transformation of insoluble sodium to soluble one in HTB coal.%对新疆的两种高钠煤(伊犁煤YL、呼图壁煤HTB)进行了N2、CO2和H2O气氛和不同温度下钠迁移的研究.采用逐级萃取和湿法消解法确定了原煤、半焦中钠的赋存形态,定量研究了两种煤中钠的挥发及迁移规律.结果表明,YL煤的形态钠中水溶钠占80.08%,HTB煤的形态钠中不溶钠占61.54%.不同气氛下,升高温度都可促进两种煤中钠的挥发,半焦中水溶钠比例减小,醋酸铵可溶钠比例会出现先增加后减少现象,盐酸可溶钠比例呈增加趋势.对于YL煤,CO2气氛可抑制钠的挥发,H2O蒸气可促进钠的挥发;900℃时,YL煤CO2气氛下钠挥发仅为N2气氛下的50.25%,而H2O气氛钠挥发为N2气氛下的111.45%.对于HTB煤,CO2气氛也可抑制钠的挥发,900℃时CO2气氛下钠挥发为N2气氛的80.91%;HTB煤在H2O蒸气下,800℃之前钠挥发高于N2,当900℃时,钠挥发略低于N2气氛.YL煤形态钠中以水溶钠为主,其挥发的同时会向盐酸可溶钠及不溶钠转变.而HTB煤形态钠中以不溶钠为主,其次是水溶钠,CO2和H2O气氛能促进不溶钠向其他可溶态钠转变.