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图牧吉油砂中有机质的提取

Extraction of Organic Substance from Tumuji Oil Sand

【作者】 孟猛

【导师】 胡浩权;

【作者基本信息】 大连理工大学 , 化学工艺, 2007, 博士

【摘要】 本文以提取油砂中有机质为目的,对内蒙古图牧吉油砂分别进行热碱水洗脱、固定床热解和加氢热解、非等温亚临界和超临界水萃取以及等温超临界二氧化碳和超临界丙烷萃取等方法的研究,考察了不同提取方法中主要因素对有机质提取率的影响,为我国油砂开发利用提供具有参考价值的方法和数据。主要研究内容和结果如下:1)在油砂热碱水洗脱实验中,考察了水洗温度、碱浓度、搅拌时间、搅拌速率和水砂比等条件对油砂中有机质洗脱率的影响。实验得到图牧吉油砂较佳水洗条件为水洗温度90℃,碱水浓度0.3%,水与油砂质量比1:1,搅拌时间90 min,搅拌速率200 r/min,洗脱率可达到90%。2)采用非等温热重法,在氮气气氛下系统地研究了油砂的热解特性,并采用不同的动力学处理方法,包括Coas-redfern法、Kissinger法、Doyle法及分布活化能模型(DAEM)法,求取了油砂的热解动力学参数。3)在固定床热解反应器中,考察了温度、压力、气体流量和停留时间等对油砂热解和加氢热解的影响。结果表明,油砂通过热解或加氢热解处理可得到较高的转化率和液体产率,产生较少的气体和热解水。在研究的实验条件范围内,油砂的热解最大转化率为87%,最高液体产率为80%;油砂的加氢热解最大转化率为95%,最高液体产率为90%。油砂热解的转化率和液体产率随温度的增加而增大,而油砂加氢热解的转化率和液体产率随温度的升高先增加而后略有降低。恒温时间对油砂热解和加氢热解的产率影响不大,载气流量对油砂热解和加氢热解产率的影响只改变有机质在液体产物和气体产物中的分配。4)在半连续超临界萃取实验设备上,以水为溶剂,对油砂进行亚临界和超临界流体非等温萃取实验,得到的最大液体产率83%。随着实验压力的增大,液体产率提高,而气体产率减少。随着实验温度的增加,液体产物及其主要组成(饱和分、芳香分和胶质)的生成速率都是先增大,在400℃左右出现峰值随后逐渐减少。随着实验压力的增加,液体产物、饱和分和芳香分的生成速率峰值所对应的温度向低温区移动,而胶质的生成速率峰值所对应的温度却向高温区移动。5)在半连续超临界萃取实验设备上,分别以二氧化碳和丙烷为溶剂,对油砂进行超临界流体等温萃取试验。随着萃取压力的升高或萃取温度的降低,萃取产率增大。以超临界丙烷为溶剂时,最大萃取产率可以达到85%,而以超临界二氧化碳为溶剂时,萃取产率很低,超临界二氧化碳不适合作为图牧吉油砂的萃取溶剂。

【Abstract】 Tumuji oil sand from Inner Mongolia was processed to get organic substance with different methods involving hot water extraction, fixed-bed pyrolysis and hydropyrolysis, non-isothermal sub-and supercritical water extraction and isothermal supercritical extraction with supercritical propane and carbon dioxide as solvent.a) With hot water extraction, the effects of experiment conditions on wash yield were investigated including temperature, stirring time, stirring rate, alkali concentration and the weight ratio of water to oil sand. The maximum 90.1% of wash yield could be obtained under the condition of temperature 90°C, alkali concentration 0.3%, water to oil sand 1:1, stirring time 90 min, and stirring rate 200 r/min.b) The pyrolysis characteristics of Tumuji oil sand were studied with thermogravimetric analysis in the stream of N2. Four kinds of methods, Coats-Redfern, Doyle, Kissinger and Distributed Activation Energy Model (DAEM), were used to determine the kinetic parameters. The results indicated that the kinetic parameters were different with different methods. DAEM is an efficient method to provide more information of the pyrolysis of oil sand.c) Pyrolysis and hydropyrolysis of Tumuji oil sand were carried out in a fixed-bed reactor to investigate the effects of temperature, pressure, gas flowrate and time on liquid yield and product fractions in liquid. A maximum of pyrolysis conversion and liquid yield of 87% and 80%, respectively, can be obtained under the studied experimental conditions, and the maximum of hydropyrolysis conversion and liquid yield is 95% and 90%, respectively. With increase of temperature, conversion, liquid yield and gas yield of pyrolysis all increase, but those of hydropyrolysis firstly increase then decrease little. Pyrolysis time at constant temperature has no evident effect and gas flowrate has an effect on the distribution of organic substance in liquid and gas.d) Tumuji oil sand was extracted with sub- and supercritical water in a semi-continuous apparatus with non-isothermal method at different pressure and different solvent flow rate. The results show that with increase of pressure, liquid yield increases while gas yield decreases. A maximum liquid yield of 83% can be obtained at 30 MPa. The results also show that the formation rates of three fractions (saturates, aromatics, resin) in extract has a maximum with the variation of temperature. The temperature corresponding to the maximum formation rates of saturates and aromatics decrease, while that of resin increases with the increase of pressure.e) Tumuji oil sand was also extracted by using supercritical propane and supercritical carbon dioxide, respectively, on a semi-continuous apparatus with isothermal method. When propane as solvent, the maximum extract yield of 85% is obtained at temperature of 110℃and pressure of 20 MPa. When carbon dioxide as solvent, the maximum extract yield is only 13% at 40℃and 25 MPa. The extract yield increases with the increasing pressure and/or with the decreasing temperature.

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