【摘要】：我國所產(chǎn)的原油大多為含蠟原油,含蠟原油是一種主要由芳香烴、石蠟、瀝青質(zhì)膠質(zhì)以及輕烴組分等組成的復(fù)雜混合物系。其中,以大慶油田為代表的原油屬于低硫石蠟基原油,石蠟基原油一般含烷烴量超過50%,具有高凝點(diǎn)、高含蠟量、高粘度的特點(diǎn),因此原油在管道輸送過程中將不可避免地產(chǎn)生蠟沉積。蠟沉積會導(dǎo)致管道有效流通面積減小,輸量降低,流動阻力增大。當(dāng)蠟沉積更為嚴(yán)重時,還將增大管道凝管的可能性,甚至還會引發(fā)管道停輸再啟動的堵管事故。本文將含蠟原油管輸蠟沉積過程視為不可逆過程,從理論上分析含蠟原油管輸過程熱質(zhì)耦合傳遞機(jī)理,分別對含蠟原油管輸?shù)膫鳠徇^程和傳質(zhì)過程進(jìn)行探討;利用熱力學(xué)相平衡理論作為研究原油中有機(jī)固相析出機(jī)理的方法,推導(dǎo)多相相平衡的熱力學(xué)判據(jù),引入正規(guī)溶液理論建立含蠟原油液一固兩相相平衡熱力學(xué)模型,采用Newton-Raphaon迭代法對二元混合物系進(jìn)行計算求解;以非平衡熱力學(xué)理論為基礎(chǔ),對管輸過程進(jìn)行簡化假設(shè),根據(jù)管輸過程的基本場平衡方程推導(dǎo)熵平衡方程,進(jìn)一步得到其熵產(chǎn)率方程,在熵產(chǎn)率方程的基礎(chǔ)上建立正確描述管道內(nèi)部傳熱傳質(zhì)過程的唯象方程組,進(jìn)而得出含蠟原油管道熱質(zhì)耦合各唯象系數(shù)數(shù)學(xué)表達(dá)式,并對各唯象系數(shù)進(jìn)行數(shù)值計算,分析溫度對各個系數(shù)的影響;對管輸含蠟原油傳熱傳質(zhì)過程進(jìn)行數(shù)值計算,得到溫度梯度及濃度梯度推動力,通過計算熱流密度與固相質(zhì)流密度深層剖析管輸過程中傳熱、傳質(zhì)的耦合機(jī)制,為深入研究含蠟原油管輸過程蠟沉積問題提供理論基礎(chǔ)。
[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.
【學(xué)位授予單位】：東北石油大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TE832

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 胡松濤，，廉樂明，李力能，魏斌;多孔磚墻體復(fù)合換熱過程的不可逆熱力學(xué)分析[J];哈爾濱建筑大學(xué)學(xué)報;1996年06期

本文編號：2273487