储油罐石油蒸发及油气排放扩散的数值模拟及风洞实验研究

There are many chances for oil vapor to emit and diffuse from oil tanks into the atmosphere in the oil operations such as storage, loading, and unloading. The emitting vapors have serious harms on people and the environment. Oil evaporation and vapor emission (OE & VE) in/from tanks are the macroscopic effects of the unsteady mass transfer of the vapor - air. The research progress of OE & VE is some slow owing to the complexity and diversity of oil operations and the loss mechanism. Thus, based on the principles of reverse engineering, wind tunnel, and similarity theory, this project is planning to conduct systematical and in-depth researches to the mechanism of OE & VE by CFD and the softwares of Fluent and MATLAB, especially using the integrated methodologies of theoretic analysis, mathematic simulation, and experimental investigation. The main research contents are described as follows..(1) Evaluate diffusion coefficients of the vapor - air..More than 60 pairs of molecular diffusion coefficients of the air (N2) - organic vapors mainly existing in the oil vapor will be experimentally measured and theoretically calculated. Based on the experimental data, the calculation method of the coefficients may be corrected and optimized..Another novel evaluation method for the turbulent diffusion coefficient is being invented and perfected according to an idea named centralized unification, and the apparent coefficients will be estimated and recommended based on the measured losses..The diffusion coefficients of both molecule and convection are very important basic data for the evaluation of OE & VE..(2) Investigate the mechanism of unsteady evaporation loss in various tanks. .In the breathing or working processes of the tanks of various oil such as gasoline, diesel oil, kerosene and crude oil, the effect factors on the OE & VE will be first analyzed, and then the distributions of gas flow field (F), gas temperature (T), and vapor concentration (C) in/from the tanks will be simulated and measured respectively. Furthermore, the evaporation losses can be calculated or measured..Especially, some noticeable cases will be considered and investigated, such as the rapid instantaneous convective mass transfer in the process of spraying oil from high tube exit into the tank, and the different effects on the the distributions of F, T, and C owing to the different locations of the vents for the internal floating-roof tanks, to the different locations of the floating deck or the different tank diameter for the external floating-roof tanks, or to the different wind speeds for the the atmosphere..Finally, the inner mechanism of OE & VE under the unsteady conditions will be discovered..(3) Improve the loss evaluation methods, and perfect the basic theory of the oil evaporation loss...The research results should provide a more perfect basic theory or more accurate basic data to the nation and the relevant industries for the evaluation of OE & VE.

石油储运中油罐严重的蒸发损耗带来许多危害。石油蒸发及油气排放扩散是非稳态油气―空气传质的宏观表现。储运操作及损耗机理复杂，国内外研究进展缓慢。基于逆向工程及风洞平台、相似理论，借助CFD、Fluent、MATLAB 等先进研究手段，从理论、实验、模拟等多角度协同研究：① 确定一套油气（有机蒸气）―空气分子扩散系数，确立更完善的计算方法；创新性地提出集中归一化对流传质拟扩散系数实测统计方法，结合损耗实测值，求出推算值。② 针对汽油、柴油、煤油及原油等大、小呼吸蒸发损耗，分析影响因素，研究油罐气体流场、浓度场及温度场、损耗量；重点考察固定顶罐高位喷射装油时快速瞬态传质过程、内浮顶罐气窗位置、外浮顶罐浮盘位置及罐径、风速对气体流场、浓度场及油气扩散的影响；揭示各种损耗内在规律。③ 构建完整的损耗评价体系，完善石油蒸发损耗的基础理论。研究结果可为国家或行业相关评估及技术改造提供理论依据及基础数据。

针对储运中非稳态石油蒸发及油气排放扩散的复杂问题，从扩散系数、蒸发损耗内在传质规律及其评价等方面，借助风洞平台及CFD、Fluent、MATLAB等手段，展开了理论、实验、数值模拟等协同研究，主要研究成果包括：.① 研究饱和蒸气压、油气摩尔质量等基础物性参数，给出了推荐值或计算式。发明了挥发性液体-气体扩散系数的测试方法及装置，测试了52组油气（有机蒸气）－空气（氮气）的分子扩散系数，获得了更完善的扩散系数计算方法。进行扩散系数的分子动力学模拟，表明该方法具有可行性。.② 创新性地提出了集中归一化对流传质拟扩散系数统计计算方法。基于逆向工程理念和油品蒸发损耗评价软件，利用损耗实测数据，反算出各种储运工况下集中归一化的对流传质拟扩散系数值，实现了对流扩散系数的定量分析，巧妙地解决了业界难以定量测算对流扩散值及其对油气传质贡献率的问题。.③ 研究了油罐各因素（拱顶罐：装油方式、装油速度、初始油气浓度、太阳照射强度；外浮顶罐：外界风速、浮盘高度、浮盘孔隙位置、意外沉盘；内浮顶罐：外界风速、浮盘高度、气窗位置）对大小呼吸损耗的影响。创新性地建立了基于单膜传质理论的油气蒸发当量膜厚数值模拟方法、基于Stefan-Fuchs方程与若干准则数关联的非稳态蒸发单相传质的数值模拟方法。研究结果揭示了各操作条件下气体空间油气运移、传质、浓度和损耗率、对大气环境扩散的内在机理与变化规律，以及影响因素的关联性，并考察了多罐储存时油气泄漏后的叠加效应。.④ 通过完善、扩充已有的油品蒸发损耗评价软件，确立了更准确的石油蒸发损耗评价方法，开发出系列评价软件，完善了损耗基础理论。.⑤ 研究成果具有明显的理论和参考价值，为制定油气排放及回收相关标准、为储罐降耗及油气回收的设计和管理提供理论依据或基础数据。除了预定研究目标，还及时将成果拓宽于指导有机废气全过程控制及回收，在技术开发、产业化及工业推广等方面，也取得了丰硕成果。.发表论文22篇（SCI/EI收录7/11篇）；申请专利12件（授权发明/实用新型专利8/2件）；获计算机软件著作权5件；编制国标1项；完成省级科技创新团队培养，1人出国进修，培养硕士生13人（7人已毕业），指导“互联网+”大学生创新创业大赛并获省二等奖；多次主办/参加国内外学术交流会并做主旨/特邀报告；获省部级科技成果一等奖2次、三等奖1次，在科技成果产业化等方面也成效明显。