Effects of secondary reaction of primary volatiles on oil/gas yield and quality in oil shale pyrolysis
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摘要: 采用两段反应器对油页岩热解释放的一次挥发分产物进行不同热态条件下的二次反应特性研究,考察第二段温度、气氛与停留时间对油气收率及品质的影响。研究结果表明,转化温度对油气产率的影响最明显,在优化第一段热解反应条件的基础上,当反应器第二段温度由600 ℃提高到650 ℃时,油页岩热解油产率下降15%(质量分数,下同),气体产率增加约20%。与氮气气氛相比,水蒸气作为第二段反应气氛能够提高液体油品收率约5%,并且热解油主要集中在馏程 < 350 ℃的汽柴油馏分。结合GC-MS分析表明,停留时间0−3 s二次反应主要为裂解过程,水蒸气能够提高油品中芳烃含量,同时抑制芳烃缩聚;3−5 s二次反应主要为缩聚过程,焦炭生成量增加,汽柴油馏分收率保持稳定,VGO馏分油收率下降约30%。Abstract: The reaction behaviors of primary volatiles from oil shale pyrolysis were investigated using a two-stage reactor under different in-situ thermal reaction conditions. The reaction parameters of secondary reactor, such as, reactor temperature, atmosphere and residence time, were studied for their effects on the pyrolysis oil/gas yield and quality. The results showed that the reaction temperature had profound influence on the oil and gas yield. The pyrolyzed shale oil and gas yield reduced by 15% and increased by 20% (mass) respectively, with the temperature of 2nd stage reactor increasing from 600 to 650 °C under optimized reaction condition of 1st stage. Comparing with nitrogen atmosphere, the liquid oil yield could be enhanced by 5% when steam was added as the reaction atmosphere in the second stage, and the corresponding oil was mainly concentrated in the gasoline and diesel distillations (that is, boiling point < 350 °C). The GC-MS analysis illustrated that the secondary reaction at the residence time of 0−3 s was mainly pyrolysis while the presence of steam could increase the content of aromatics in the oil and meanwhile suppress the condensation of aromatics. When the residence time was greater than 3−5 s, the secondary reaction was mainly condensation of poly-aromatics, which led to the increase of coke. Meanwhile, the gasoline and diesel oil yield remained stable, and the VGO fractions decreased by about 30%.
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Key words:
- oil shale /
- pyrolysis volatiles /
- steam reforming /
- secondary reaction
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表 1 桦甸油页岩的工业分析、元素分析和铝甑分析
Table 1 Proximate, ultimate and Fischer assay analyses of Huadian oil shale
Proximate analysis wd/% Ultimate analysis wad/% Fischer assay wad/% A V FC C H O* N S oil gas water coke 49.94 33.14 16.92 34.32 3.56 11.02 0.89 0.78 11.30 9.62 3.92 75.16 d: dry basis; ad: air-dried basis; *: calculated by difference -
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