含蜡原油管输不可逆热—质耦合过程的唯象研究
发布时间：2018-10-15 18:46
【摘要】：我国所产的原油大多为含蜡原油,含蜡原油是一种主要由芳香烃、石蜡、沥青质胶质以及轻烃组分等组成的复杂混合物系。其中,以大庆油田为代表的原油属于低硫石蜡基原油,石蜡基原油一般含烷烃量超过50%,具有高凝点、高含蜡量、高粘度的特点,因此原油在管道输送过程中将不可避免地产生蜡沉积。蜡沉积会导致管道有效流通面积减小,输量降低,流动阻力增大。当蜡沉积更为严重时,还将增大管道凝管的可能性,甚至还会引发管道停输再启动的堵管事故。本文将含蜡原油管输蜡沉积过程视为不可逆过程,从理论上分析含蜡原油管输过程热质耦合传递机理,分别对含蜡原油管输的传热过程和传质过程进行探讨;利用热力学相平衡理论作为研究原油中有机固相析出机理的方法,推导多相相平衡的热力学判据,引入正规溶液理论建立含蜡原油液一固两相相平衡热力学模型,采用Newton-Raphaon迭代法对二元混合物系进行计算求解;以非平衡热力学理论为基础,对管输过程进行简化假设,根据管输过程的基本场平衡方程推导熵平衡方程,进一步得到其熵产率方程,在熵产率方程的基础上建立正确描述管道内部传热传质过程的唯象方程组,进而得出含蜡原油管道热质耦合各唯象系数数学表达式,并对各唯象系数进行数值计算,分析温度对各个系数的影响;对管输含蜡原油传热传质过程进行数值计算,得到温度梯度及浓度梯度推动力,通过计算热流密度与固相质流密度深层剖析管输过程中传热、传质的耦合机制,为深入研究含蜡原油管输过程蜡沉积问题提供理论基础。
[Abstract]:Most of the crude oil produced in China is waxy crude oil. Waxy crude oil is a complex mixture mainly composed of aromatics, paraffin wax, asphaltene resin and light hydrocarbon components. Among them, the crude oil represented by Daqing Oilfield belongs to low-sulfur paraffin base crude oil. Paraffin based crude oil generally contains more than 50 alkanes and has the characteristics of high freezing point, high wax content and high viscosity. Therefore, wax deposition will inevitably occur during the pipeline transportation of crude oil. Wax deposition will decrease the effective flow area, decrease the transportation volume and increase the flow resistance. When wax deposition is more serious, it will increase the possibility of pipeline condensation, and even lead to the blockage of pipeline shutdown and restart. In this paper, the deposition process of waxy crude oil pipeline transportation is regarded as an irreversible process. The heat and mass coupling transfer mechanism of waxy crude oil pipeline transportation is analyzed theoretically, and the heat transfer process and mass transfer process of waxy crude oil pipeline transportation are discussed respectively. Using the thermodynamic phase equilibrium theory as the method to study the mechanism of organic solid phase precipitation in crude oil, the thermodynamic criterion of multiphase equilibrium is deduced, and the thermodynamic model of liquid-solid two-phase equilibrium of waxy crude oil is established by introducing the regular solution theory. The binary mixture system is calculated and solved by Newton-Raphaon iteration method. Based on the theory of non-equilibrium thermodynamics, the simplified assumption of pipeline transportation process is made, and the entropy equilibrium equation is derived according to the basic field equilibrium equation of pipeline transportation process. On the basis of the entropy yield equation, the phenomenological equations describing the heat and mass transfer process in the pipeline are established, and the mathematical expressions of thermo-mass coupling phenomenological coefficients for waxy crude oil pipeline are obtained. The influence of temperature on each coefficient is analyzed, and the heat and mass transfer process of waxy crude oil is numerically calculated, and the driving force of temperature gradient and concentration gradient is obtained. The coupling mechanism of heat transfer and mass transfer during pipe transportation is analyzed by calculating the heat flux and solid mass flow density, which provides a theoretical basis for the further study of wax deposition in pipeline transportation of waxy crude oil.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE832
本文编号：2273487
[Abstract]:Most of the crude oil produced in China is waxy crude oil. Waxy crude oil is a complex mixture mainly composed of aromatics, paraffin wax, asphaltene resin and light hydrocarbon components. Among them, the crude oil represented by Daqing Oilfield belongs to low-sulfur paraffin base crude oil. Paraffin based crude oil generally contains more than 50 alkanes and has the characteristics of high freezing point, high wax content and high viscosity. Therefore, wax deposition will inevitably occur during the pipeline transportation of crude oil. Wax deposition will decrease the effective flow area, decrease the transportation volume and increase the flow resistance. When wax deposition is more serious, it will increase the possibility of pipeline condensation, and even lead to the blockage of pipeline shutdown and restart. In this paper, the deposition process of waxy crude oil pipeline transportation is regarded as an irreversible process. The heat and mass coupling transfer mechanism of waxy crude oil pipeline transportation is analyzed theoretically, and the heat transfer process and mass transfer process of waxy crude oil pipeline transportation are discussed respectively. Using the thermodynamic phase equilibrium theory as the method to study the mechanism of organic solid phase precipitation in crude oil, the thermodynamic criterion of multiphase equilibrium is deduced, and the thermodynamic model of liquid-solid two-phase equilibrium of waxy crude oil is established by introducing the regular solution theory. The binary mixture system is calculated and solved by Newton-Raphaon iteration method. Based on the theory of non-equilibrium thermodynamics, the simplified assumption of pipeline transportation process is made, and the entropy equilibrium equation is derived according to the basic field equilibrium equation of pipeline transportation process. On the basis of the entropy yield equation, the phenomenological equations describing the heat and mass transfer process in the pipeline are established, and the mathematical expressions of thermo-mass coupling phenomenological coefficients for waxy crude oil pipeline are obtained. The influence of temperature on each coefficient is analyzed, and the heat and mass transfer process of waxy crude oil is numerically calculated, and the driving force of temperature gradient and concentration gradient is obtained. The coupling mechanism of heat transfer and mass transfer during pipe transportation is analyzed by calculating the heat flux and solid mass flow density, which provides a theoretical basis for the further study of wax deposition in pipeline transportation of waxy crude oil.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE832
【参考文献】
相关期刊论文 前1条
1 胡松涛，，廉乐明，李力能，魏斌;多孔砖墙体复合换热过程的不可逆热力学分析[J];哈尔滨建筑大学学报;1996年06期
本文编号：2273487
本文链接：https://www.wllwen.com/kejilunwen/shiyounenyuanlunwen/2273487.html
