【作者】 杨春雪；

【导师】 冯杰；

【作者基本信息】 太原理工大学 ， 化学工艺， 2008， 硕士

【摘要】 在全球石油价格持续上涨,液体燃料匮乏的背景下,煤炭直接液化技术对于调整能源结构、扩大液体燃料来源、缓解我国能源分布不均具有重要的意义。但煤液化油组成复杂,结构不均一,液化过程工艺影响因素众多,工艺设计中可参考的经验少,尤其是关键部分反应器、分离器的设计中所需要的液化产品的基础数据匮乏,特别是在煤液化反应条件下气液平衡数据的测定难以实现。因此,得到煤液化油的基本物性和热力学数据是液化工艺精确设计的基本保证。本文依托于973项目“大规模煤炭直接液化的基础研究”,从煤液化油的基本物性参数测定出发,利用流程模拟软件Aspen Plus计算了在煤液化反应条件下,煤液化油气液两相平衡关系及相关的基础数据。计算中以实验测定液化油窄馏分段的基本物性数据作为基础,用COAL-LIQ模块计算构建神华煤液化油各窄馏分的模拟组分（虚拟组分模型）,以物料守恒,能量守恒为基础,将煤液化油虚拟组分与各种气体组分（如H₂、C₂H₆等）共同建立煤液化油闪蒸过程,得到了高温高压下煤液化油气液平衡体系。利用闪蒸体系计算得到在给定温度、压力情况下,各组分在高温、低温分离器内的气、液两相分布情况,通过改变高温分离器的温度和压力,分析了高温分离器内相平衡常数随温度（623.15～723.15K）、压力（10～21Mpa）同时变化的规律。为进一步归纳适用于煤液化油的气液平衡方程,以高温分离器数据为基础,对推导建立的高压下烃类相平衡方程中的参数进行回归,得到高温高压下,适用于神华煤液化油并具有物理意义的二元（T,p）气液相平衡常数方程。以分离模型为基础,分析了闪蒸过程中神华煤液化油馏分密度,粘度,表面张力随温度变化规律,建立了闪蒸分离器各出口组成的十六烷指数与温度压力的关系。通过实验与计算分析,本文得到如下主要结论:1、神华煤液化油主要包括饱和直链烷烃,环烷烃,苯及其衍生物,苯酚及其衍生物,茚及其衍生物,萘及其衍生物等。饱和直链烷烃在各馏分段都有分布,规律性不强。环烷烃在低温馏分段含量较高。苯酚及其衍生物在200℃左右馏分段含量最高。茚及其衍生物,萘,四氢化萘在200～220℃段以后出现,茚类物质在各段中含量都不高于8%,萘类物质随馏分温度升高呈增大的趋势,特别地,在280～300℃段,萘类物质连同联苯占到49.7%。2、神华煤液化油窄馏分段临界温度随蒸馏温度升高而升高。临界压力随馏出温度升高呈现先上升后下降的趋势,180～200℃段跃至最高点。临界体积随馏出温度的升高呈现先下降后上升的趋势。临界压力,临界体积极值的出现归因于此馏分段中大量酚类物质的富集。3、通过闪蒸分离系统,计算得到了给定条件下,高温、低温分离器中各组分在气液两相中的分布情况。高温分离器中,气体以气相形式存在,馏分段部分气化,气化程度随蒸馏温度升高而降低,低温分离器中,各馏分段基本以液态形式存在。4、各组分相平衡常数随温度、压力变化的规律是,气体组分的相平衡常数受温度、压力的影响较各馏分大,在温度为703.15K下,所有组分气液平衡常数随压力的增大而减小,高温馏分段平衡常数变化不明显（变化小于0.025）。15MPa下,各馏分段的气液平衡常数随温度的升高而增大,气体组分相平衡常数随温度的升高而降低。5、根据相平衡数据建立神华煤液化油高温、高压下,并具有物理意义的二元（T,p）气液相平衡常数方程,ln K₁=A+Bp-ln p-Cp/T-D/T-Ep/T^F,相关系数多为0.999,表明该方程具有较高的可靠性。6、在300～685K的范围内,分析闪蒸过程中,各馏分段的密度、粘度、表面张力随温度变化的规律,建立了密度、粘度、表面张力关于温度的计算方程。7、分析高温、低温分离器各出口油品的十六烷指数（CI值）随温度、压力变化的关系,对高温、低温分离器在不同工艺条件下的数据进行数学回归,建立了高温、低温分离器液相出口油品十六烷指数与温度、压力的二元数学模型,可利用这些模型进行产品油质量的预测,达到有效调控生产的目的。更多还原

【Abstract】 As the availability of petroleum feedstock becomes uncertain coal liquefaction is expected of a promising way to optimize energy structure and to provide a significant part of the liquid fuels of the future.Several investigation of coal liquefaction are hampered by the unavailability of thermodynamic and physical property data at the reactor running conditions.Nevertheless,these data are essential properties in the reactor design,fractionating towers operation parameters selection,and other process condition optimization.Additionally,the vapor-liquid equilibrium composition of each component would determine not only the size of reactor,but also affect the selection of hydrogen-donor-liquid. Essentially nothing is known about China Shenhua coal liquids.The lack of the basic data reported and the inappropriate applying of the equilibrium data in the literature make us achieve this knowledge of coal liquids.The normal properties such as density,the structure of the coal liquefied oil were gotten by detecting instruments.However,the equilibrium compositions of typical coal liquefiers,which are running at 600～700K and more than 10MPa, are difficult to measure by instruments.The correlation equations are not available way because of the complex of multi-component calculation and the lack of the corresponding parameters.So the simulation software package Aspen Plus which was known for its abundant parameters in the database and its excellent simulation was introduced.This study was supported by the fundamental research project of coal direct liquefaction at large scale（973 PROGRAM）.The steps of calculation were as follows:First,the pseudo-components were built up with the COAL-LIQ method based on the physical data of the fractions of coal liquefied distillation oil.And some thermodynamic properties（such as critical properties and acentric factor）were gotten.In order to get the vapor-liquid equilibrium constants under the real liquefaction conditions,the pseudo-components and existing gas,such as H₂ and C₂H₆,were combined together to establish the coal liquefied oil flash distillation system through the Aspen Plus.By using the flash-distillation system, the vapor-liquid equilibrium composition and distribution were calculated at reaction temperature and pressure.Also the rules of equilibrium constant vary with the temperature（623.15～723.15K）and pressure（10～21Mpa）were explored.Furthermore,the parameters of deducing hydrocarbon equilibrium equation at high pressure were regressed.And the two variables vapor-liquid equilibrium equation specified for the Shenhua coal liquefied oil was established. In order to evaluate the quality of the outlet oil efficiently,the calculated cetane index（CI）equations of different compositions were built based on the CI of different flash outlet data at various conditions.Through detection and thermodynamic calculation,the following conclusions can be educed:1、The Shenhua coal liquids are mainly composed of the following materials,alkane,naphthenic hydrocarbons,benzene derivative,phenol, indene,naphthalanene derivative,and so on.Saturated hydrocarbons can be detected in all the fractions.The naphthenic hydrocarbons are mainly in the low temperature fractions.The benzene and its derivatives has the highest content in the fractions about 200℃.The indene,naphthalanene and their derivatives appeared after 220℃.The naphthalanene derivatives and biphenyl accounts for 49.7%in the 280～300℃fraction.2、T_cs of Shenhua coal liquid fractions are proportional to their distilling temperatures（DT）.With increase of the DT,p_cs increase first,then decreased after 200℃while the V_cs have the different trend.The peak and valley of the p_cs and V_cs because of the enrichment of hydroxybenzene in the 180～200℃.3、By using the flash-distillation system,the vapor-liquid equilibrium composition and distribution were calculated at reaction temperature and pressure.In the high temperature separator,some of the fractions were evaporated,and the content decreased with the increase of the distillation temperature.The fractions mainly existed in liquid in the low temperature separator.4、The equilibrium constants（K）of all the compositions had the same trends with the pressure.And the Ks of gases were observably affected by the temperature and pressure.Under 693.15K,the Ks of fractions（higher than 300℃）changed less than 0.025 when pressure increased 10MPa.But the gases and the fractions have different trends when the temperature increased under 15MPa.5、The parameters of deducing hydrocarbon equilibrium equation at high pressure were regressed.And the two variable vapor-liquid equilibrium equation specified for the Shenhua coal liquefied oil was established, ln K₁=A+Bp-ln p-Cp/T-D/T-Ep/T^F.6、At the range of 300～685K,the density,viscosity,surface tension of the fractions were studied,and the relationships were gotten by regression.7、By nonlinear regression analysis,the relationship between the CI of the compositions with temperature（t）and pressure（p）were obtained.These equations can help to determine the optimal conditions by forecasting the quality of the fractions.更多还原