發(fā)布時間：2019-01-24 16:38

【摘要】：褐煤在我國資源豐富,因其高水分、高揮發(fā)分以及低發(fā)熱量等特點,使得褐煤的化學(xué)反應(yīng)性差別較大,因此采用不同預(yù)處理方法對褐煤結(jié)構(gòu)及熱化學(xué)性能進行研究,有利于了解褐煤的本質(zhì)特性。選用勝利褐煤作為研究對象,通過溶劑(丙酮、四氫呋喃以及N-甲基吡咯烷酮/二硫化碳的混合)溶脹、水熱溶劑(N-甲基吡咯烷酮和N-甲基吡咯烷酮/二硫化碳的混合)抽提以及堿處理(氫氧化鈉)方法對煤樣進行預(yù)處理,并采用工業(yè)分析、FT-IR、BET、SEM以及氧吸附等手段對所制樣品進行表征,考察了煤樣的熱解和燃燒性能,系統(tǒng)研究了堿處理煤樣的熱化學(xué)反應(yīng)性。實驗結(jié)果表明,勝利褐煤在四氫呋喃溶劑中的溶脹度最大,N-甲基吡咯烷酮和二硫化碳的混合溶劑次之,丙酮最小。對褐煤進行酸洗、氧化以及堿預(yù)處理,酸洗和氧化煤樣的溶脹度均有所提高,堿處理煤樣的溶脹度降低。對預(yù)處理四氫呋喃溶脹煤樣進行低溫氧吸附測試,結(jié)果表明,其低溫氧化活性明顯低于勝利褐煤,不易自燃。不同水熱溶劑抽提煤樣的燃燒反應(yīng)特性有一定的差別,與勝利褐煤相比,其主體燃燒峰均向高溫區(qū)移動,燃燒性能變差。水熱溶劑抽提煤樣的熱解特征參數(shù)值表明,SR150℃NMP/CS2的最大失重速率高于其它煤樣,所對應(yīng)的最大失重溫度低于其它煤樣,說明此煤樣具有良好的熱解性能。不同濃度的堿處理煤樣與勝利褐煤相比,其主體燃燒峰均向高溫區(qū)移動,堿濃度為0.5mol/L和1mol/L的煤樣在550℃之后出現(xiàn)了明顯的燃燒滯后現(xiàn)象,說明堿處理煤樣的燃燒性能降低,且堿濃度越大其燃燒性能越差。在水蒸氣氣化過程中,堿處理煤樣的生成氣主要是H2和CO2,其生成H2和CO2的最大生成速率值所對應(yīng)的溫度均提前20℃左右,氣化起始溫度比勝利褐煤均提前60℃左右,由此可知,堿處理對勝利褐煤的水蒸氣氣化性能有所提高。
[Abstract]:Lignite is rich in resources in China. Because of its high moisture content, high volatile content and low calorific value, the chemical reaction property of lignite varies greatly. Therefore, different pretreatment methods are used to study the structure and thermochemical properties of lignite. It is helpful to understand the essential characteristics of lignite. Shengli lignite was selected as the object of study, which was swelled by solvent (acetone, tetrahydrofuran and N-methylpyrrolidone / carbon disulfide). Hydrothermal solvent extraction (mixture of N-methylpyrrolidone and N-methylpyrrolidone / carbon disulfide) and alkali treatment (sodium hydroxide) pretreatment of coal samples were carried out, and industrial analysis, FT-IR,BET, The samples were characterized by SEM and oxygen adsorption. The pyrolysis and combustion properties of coal samples were investigated. The thermochemical reaction of coal samples treated with alkali was studied systematically. The experimental results show that Shengli lignite has the highest swelling degree in tetrahydrofuran solvent, followed by the mixture of N-methylpyrrolidone and carbon disulfide, and the smallest in acetone. The swelling degree of lignite samples was increased by acid washing, oxidation and alkali pretreatment, while the swelling degree of alkali treated coal samples was decreased. The low temperature oxygen adsorption test of pretreated tetrahydrofuran swelling coal samples shows that the oxidation activity at low temperature is obviously lower than that of Shengli lignite and it is not easy to spontaneous combustion. The combustion reaction characteristics of coal samples extracted by different hydrothermal solvents are different. Compared with Shengli lignite, the main combustion peak shifts to high temperature and the combustion performance becomes worse. The pyrolysis characteristic parameters of the coal sample extracted by hydrothermal solvent show that the maximum weight loss rate of NMP/CS2 at SR150 鈩，

本文編號：2414632