预处理对胜利褐煤微结构及其热化学性能影响的研究
发布时间：2019-01-24 16:38
【摘要】：褐煤在我国资源丰富,因其高水分、高挥发分以及低发热量等特点,使得褐煤的化学反应性差别较大,因此采用不同预处理方法对褐煤结构及热化学性能进行研究,有利于了解褐煤的本质特性。选用胜利褐煤作为研究对象,通过溶剂(丙酮、四氢呋喃以及N-甲基吡咯烷酮/二硫化碳的混合)溶胀、水热溶剂(N-甲基吡咯烷酮和N-甲基吡咯烷酮/二硫化碳的混合)抽提以及碱处理(氢氧化钠)方法对煤样进行预处理,并采用工业分析、FT-IR、BET、SEM以及氧吸附等手段对所制样品进行表征,考察了煤样的热解和燃烧性能,系统研究了碱处理煤样的热化学反应性。实验结果表明,胜利褐煤在四氢呋喃溶剂中的溶胀度最大,N-甲基吡咯烷酮和二硫化碳的混合溶剂次之,丙酮最小。对褐煤进行酸洗、氧化以及碱预处理,酸洗和氧化煤样的溶胀度均有所提高,碱处理煤样的溶胀度降低。对预处理四氢呋喃溶胀煤样进行低温氧吸附测试,结果表明,其低温氧化活性明显低于胜利褐煤,不易自燃。不同水热溶剂抽提煤样的燃烧反应特性有一定的差别,与胜利褐煤相比,其主体燃烧峰均向高温区移动,燃烧性能变差。水热溶剂抽提煤样的热解特征参数值表明,SR150℃NMP/CS2的最大失重速率高于其它煤样,所对应的最大失重温度低于其它煤样,说明此煤样具有良好的热解性能。不同浓度的碱处理煤样与胜利褐煤相比,其主体燃烧峰均向高温区移动,碱浓度为0.5mol/L和1mol/L的煤样在550℃之后出现了明显的燃烧滞后现象,说明碱处理煤样的燃烧性能降低,且碱浓度越大其燃烧性能越差。在水蒸气气化过程中,碱处理煤样的生成气主要是H2和CO2,其生成H2和CO2的最大生成速率值所对应的温度均提前20℃左右,气化起始温度比胜利褐煤均提前60℃左右,由此可知,碱处理对胜利褐煤的水蒸气气化性能有所提高。
[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，
本文编号：2414632
[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，
本文编号：2414632
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