洁净煤技术

2019, (04) 40-45

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新疆东疆褐煤直接加氢液化特性
Direct hydroliquefaction characteristics of lignite in eastern area of Xinjiang

赵鹏;
ZHAO Peng

摘要(Abstract):

为实现新疆东疆煤的清洁高效利用,对新疆东疆褐煤进行煤质与组成分析,以新疆东疆褐煤与加氢溶剂为原料,在500 m L搅拌式高压釜中进行加氢液化的过程调控试验,考察了反应温度、反应压力和停留时间对氢耗率、气产率、转化率、油产率、沥青质产率的影响规律,探究了不同工艺参数对液化性能及各类产物分布的内在作用机制,进行了0. 01 t/d连续试验的验证,并深入解析了液化初级油品的结构组成特征。结果表明,新疆东疆褐煤液化活性组分高达90%,具有高挥发分和高H/C原子比的煤质特征,在反应温度430℃,反应压力15 MPa和60 min的缓和反应条件下,煤的转化率高达94%,油产率57%,依然呈现出与传统反应条件(反应温度450℃,反应压力17 MPa,反应时间60min)相当的反应性能和液化效果,是一种适宜直接加氢液化的优质原料,反应条件的缓和使反应器温控更加平稳,有利于降低大型液化设备的能耗。过程调控表明,反应温度升至430℃,有效促进了煤和沥青质向油和气的转化,导致转化率和油产率增加;高氢压有利于氢气在液化体系中的溶解,有利于稳定自由基碎片,增强了沥青质中稠环芳烃加氢向小分子的转化; 30 min新疆东疆褐煤已呈现出良好的液化效果和反应性能,时间延长至90 min,铁系催化剂的活性相Fe7S8在加氢液化反应过程中逐渐转变为Fe9S10,甚至是FeS等非活性态,催化能力明显降低,引发了沥青质的缩聚反应,导致沥青质产率升高,转化率和油产率下降。0. 01 t/d新疆东疆褐煤连续试验获得的直接加氢液化初级油保留了煤的一些结构组成特征,具有高密度、高芳烃、高氮低硫的特点,<220℃馏分油20℃密度为851. 2 kg/m~3,220~350℃馏分油20℃密度为953. 5 kg/m-3,2种馏分初级油的主要组成为单环芳烃,均为60%左右,这是由多环芳烃易加氢生成单环芳烃,而单环芳烃加氢或开环反应较为困难所致。<220℃馏分油氮含量为2 500×10~(-6),220~350℃馏分油氮含量为4 800×10~(-6),均比各自的硫含量高一个数量级。
In order to find a clean and high efficient technology for economic utilization of Xinjiang coal,the coal quality and composition of lignite in East Xinjiang were analyzed.In Lignite of eastern Xinjiang and hydrogenation solvent as raw materials,hydrogenation regulation test was carried out in 500 mL stirring autoclave to investigate influences of temperature,pressure and residence time on hydrogen consumption,gas,conversion,oil and asphaltene.The effects of process parameters on liquefaction performance and distribution of various products were investigated.A verification test was finished in 0.01 t/d BSU and the structural characteristics of liquefied primary oil products were analyzed in depth.The results show that the active component is 90% in the lignite of eastern Xinjiang with the characteristics of high volatile and H/C atom ratio.Under the moderate conditions (430 ℃,15 MPa and 60 min),the conversion of coal is up to 94% and the oil yield is 57%,which is similar to that under the traditional conditions(450 ℃,17 MPa and 60 min).The lignite is a high quality raw material for direct liquefaction.Moderate conditions contribute much to smooth temperature control of reactor,which is conducive to reducing energy consumption of large equipment.Process regulation test shows that the conversion of coal and asphaltene to oil and gas is promoted effectively,resulting in the increase of coal conversion and oil yield by increasing temperature especially at 430 ℃.High hydrogen pressure is conducive to the dissolution of H2 in reaction system,the stability of radical fragment and the hydrogenation of polycyclic aromatic hydrocarbons in asphaltene to small molecules.The lignite is possessed of favorable liquefaction effect and reaction performance at 30 min.Due to the phase transform of iron based catalyst in reaction system from active Fe7S8to nonactive Fe9S10 and FeS at 90 min,the catalytic ability decreases significantly,which leads to the condensation reaction of asphaltene,the increase of asphaltene yield and the decrease of coal conversion and oil yield.Retaining some structural characteristics of coal,the primary oil from hydrogenation liquefaction continuous test of the lignite in eastern area of Xinjiang has the characteristics of high density,high aromatic hydrocarbon,high nitrogen and low sulphur.The 20 ℃ density of <220 ℃ fraction is 851.2 kg/m3.The 20 ℃ density of 220-350 ℃ fraction is 953.5 kg/m3.The main structure in the primary oil of <220 ℃ and 220-350 ℃ fraction is mononuclear aromatics(60%) caused by the easy hydrogenation of polycyclic aromatic hydrocarbon and the difficult ring opening reaction of mononuclear aromatics.Nitrogen content in <220 ℃ fraction is 2 500×10-6 and 4 800×10-6 in 220-350 ℃ fraction,which is one order higher than sulphur content respectively.

关键词(KeyWords): 低阶煤;加氢液化;初级油;反应温度;反应压力;停留时间
low rank coal;hydroliquefaction;primary oil;reaction temperature;reaction pressure;residence time

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作者(Author): 赵鹏;
ZHAO Peng

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