【作者】 贾春霞；

【导师】 王擎；

【作者基本信息】 华北电力大学 ， 热能工程， 2014， 博士

【摘要】 本文采用先进测试技术和实验手段,探索了化学结构特征与热解反应性之间的关系。基于油砂热解过程中微观变化规律,从理论和试验两个方面系统地开展油砂热解特性的研究,从本质上揭示了油砂热解特性及其产物生成机理。本文主要从以下几方面开展研究工作：采用热失重分析技术系统研究了油砂的热分析特性,获得了油砂热解过程中Thermal Gravity Analysis-Differential thermal gravity(TG-DTG)、Thermal Gravity Analysis-Differential Scanning Calorimetry(TG-DSC)及Thermal Gravity Analysis-Fourier Transform Infrared(TG-FTIR)曲线变化规律,结果分析表明,油砂热解过程包括脱水阶段、油砂沥青的低温裂解、碳氢化合物的分解及高温段的矿物质裂解四个阶段。详细研究了升温速率、反应气氛、终温等重要因素对油砂热解特性的影响。理论上,采用Coats-Redfern(C-R)法、Flynn-Wall-Ozawa(F-W-O)法、分布活化能模型(DAEM)、非传统Arrhenius法及多峰拟合法等理论模型对油砂热解动力学特性进行了广泛的研究,建立了油砂热解反应动力学模型,获得了活化能、频率因子等热解动力学参数,探究了油砂在整个热解过程中活化能随着热解转化率的变化规律。用非对称高斯(bi-Gauss)多峰拟合法来分离重叠峰,确定了油砂热解反应机理函数,结果表明,bi-Gauss法在拟合效果上优于经典的高斯法,子峰近似遵循单一反应机理,主产油阶段不遵循单一反应机理,主产油阶段与子峰机理函数高度吻合等结论,验证了双组分叠加反应模型的适用性。本文进一步研究了油砂的燃烧特性,获得了模拟空气气氛下油砂的着火温度、燃烧稳定性判别指数和燃烧反应性能参数。在此基础上,运用“非对称高斯多峰拟合法”对油砂燃烧放热峰进行分离拟合,将实验DSC曲线复杂峰有效分离为多个高斯函数峰,探讨了不同伪组分的燃烧反应热对油砂燃烧总的热效应的贡献,结合Malek法确定了油砂燃烧时其伪组分的最概然机理函数,结果表明,每种伪组分反应机理函数不同。利用TG-FTIR联用技术对油砂热解过程中气相产物析出规律进行了实验研究,考察了升温速率等因素对气相产物CO2、CO、H2和CH4等气体组分析出的影响,揭示了可燃气组分的析出机理。在自行设计搭建的固定床反应器上进行了油砂热解的实验研究,系统地研究了升温速率、终温等操作条件对其热解特性的影响,优化了油砂热解的关键参数。结果表明,当热解温度相同时,气体和液体产率随着升温速率的增加而增加；热解半焦产率随着升温速率的增加而减少。利用气相色谱仪对油砂热解的气体产物组分进行分析,结果表明,热解气体产物中主要含有CO、CO2、 H2、CH4、C2H4、C2H6等可燃气体。油砂热解得到的气体热值均在33MJ/m3左右,随着热解温度的提高,热解气体的热值均呈现先升高后降低的趋势。详细研究了油砂干馏过程中固体产物半焦孔隙结构变化,结果表明,干馏终温对油砂半焦吸附量影响较大。利用傅里叶红外光谱仪(FTIR)研究了官能团随反应终温的演化规律,进一步从微观角度揭示油砂热解反应机理。通过对红外光谱谱图的分析,研究了油砂半焦中的芳香烃、脂肪烃、羟基官能团及含氧官能团,并对各个官能团谱图进行了高斯峰分峰拟合,确定了有机组分特征吸收峰,同时获得了富氢程度、脂肪结构、芳香度等参数,以利于油砂结构研究。利用核磁共振技术对不同干馏终温下的油砂油样品进行了’H与13C NMR实验研究。根据谱峰归属对每个谱图积分,采用改进的Brown-Ladner计算方法计算其平均结构参数。通过分析结构参数随干馏终温的变化,研究了干馏终温对油砂油化学结构的影响。结果显示,随着干馏终温的升高,油砂干馏生成油化学结构有明显变化。更多还原

【Abstract】 With advanced testing techniques and experimantal methods, this paper specially focuses on the relationship between the chemical structre features and pyrolysis reaction characteristic. Based on the microcosmic change of oil sand during pyrolysis process, pyrolysis characteristics of oil sands were studied systematically from theoretical and experimental aspects. Then the pyrolysis reaction characteristics of oil sand was considered, so as to reveal the pyrolysis products generation mechanism essentially. Specifc research content are listed in the following:Pyrolysis experiments of oil sand were conducted on thermo-gravimetric analyzer with different heating rate, particle size and reaction atmosphere, respectively. The characteristics of oil sand pyrolysis based on the technologies of TG-DTG^TG-DSC and TG-FTIR have been obtained. The results show that all oil sands pyrolysis process includes four stages:initial dehydration, low temperature pyrolysis of bitumen, the decomposition of hydrocarbons and high temperature pyrolysis of minerals. Theoretically, kinetic parameters of oil sand pyrolysis were calculated. A lot of methods, such as Coats-Redfern method, Flynn-Wall-Ozawa method, DAEM method, untraditional Arrhenius theory and multiple peaks fitting method, have been extensively used to determine the activation energy and frequency factor. The change laws of Activation energy with the conversion relations in the pyrolysis process are received. An asymmetric multi-peak fitting method, bi-Gauss, was creatively introduced to separate the overlapping peak, and the oil sand pyrolysis reaction mechanism functions are determined. The results show that the bi-Gauss method can produce more satisfactory fitting results than the classical Gauss method. Moreover, the subpeaks follow a single mechaniasm, the overall stage does not follow a single mechanism and the mechanisms of the front and back segments of the overall stage are in accordance with those of the subpeaks, which prove the applicability of the two-component parallel model.In this paper, the combustion characteristics of oil sand were further studied. Also some combustion parameters such as:ignition temperature, the combustion stability Discriminant index and combustion reaction performance parameters were obtained. On this basis, the complex peaks of experimental DSC curves were effectively separated into multiple Gaussian function peaks, and the contribution of different pseudo components’combustion heat to the total heat effect of oil sands were discussed. Finally, the kinetic mechanism functions of each oil sand components were determined according to Malek’s method, and the result shows that different component has different mechanism function.The gas products release characteristics during pyrolysis process was studied using TG-FTIR spectrometry, which examined the influence of heating rate on the release law of CO2, CO, H2and CH4. That revealed the release mechanism of gas products during oil sand pyrolysis.Pyrolysis experiments of oil sand were conducted in a bench-scale fixed-bed reactor to investigate the effect of temperature, heating rate on liquid and gas yield, the key pyrolysis parameters of oil sands were optimized. With increase of temperature, liquid yield and gas yield of pyrolysis all increase, but the char yield decrease. The gas product components were determined by using gas chromatograph analysis. The results showed that the major gases produced during oil sand pyrolysis were CO, CO2, H2, CH4, C2H4and C2H6. Gas calorific value is about33MJ/m3, with the increase of pyrolysis temperature, pyrolysis gas calorific values were presented a trend of firstly increase then decrease little.In this paper, the pore structure of oil sand char at different pyrolysis temperature was investigated in detail, and the pyrolysis temperature had a greater influence on the adsorption quantity of oil sands char. the FTIR experiment was used to analyze various functional groups characteristics, from which the oil sands pyrolysis reaction mechanism from the microscopic view revealed, the aromatic hydrocarbon, aliphatic hydrocarbon, hydroxyl and the oxygen functional groups in the samples were determined.Each functional group curve was separated into multiple Gaussian function peaks, then the characteristic absorption peak of organic component was determined, so as to receive the degree of rich hydrogen, the structure of the aliphatic hydrocarbon, aromaticity and other parameters.The1H and13C NMR experiments of oil sands oil were conducted on nuclear magnetic resonance spectrometer. Each spectrum was analyzed according to the spectral peaks affiliation, the improved Brown-Ladner method was used to calculate the average structure parameters of oil. The results show that, with the increase of the pyrolysis temperature, the oil chemical structure have obvious change.更多还原