外浮顶罐不同孔隙油气泄漏扩散数值模拟
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摘要
开展外浮顶罐油气泄漏扩散机理及规律的研究对于保障罐区安全、降低环境污染具有重要的意义。针对大、小外浮顶罐不同浮盘孔隙的油气泄漏扩散及其受风场的影响进行了数值模拟及实验验证。研究结果如下。①当风吹向外浮顶罐时,会在浮盘上方形成大尺度涡流,并在紧贴浮盘处形成从下风侧到上风侧的对称分布的气流运移。②泄漏位置在浮盘上时,油气均紧贴浮盘从下风侧向上风侧运移;泄漏位置位于浮盘中间及下风侧时,油气较容易扩散出去,而位于浮盘上风侧及两侧时,油气容易发生积聚,存在很大的安全隐患;风速增大有利于油气扩散,但会使污染范围扩大。③泄漏位置在浮盘与罐壁之间的边圈缝隙时,油气沿着罐壁向浮盘上方空间扩散,且扩散的程度为:浮盘两侧>上风侧>下风侧。④泄漏位置在浮盘中心、泄漏孔径为20mm时,正庚烷体积分数为0.1%～1.7%,处在对应的爆炸极限范围之内;而孔径为6mm时,正庚烷体积分数在0.02%～0.26%,汽油蒸气的体积分数在0.05%～0.65%,均未达到爆炸极限范围。因此,当泄漏孔隙较大时,出现爆炸危险的可能性增大。研究成果进一步揭示浮盘上方气流运移规律及油气扩散传质机理,可为生产实践和油罐管理提供理论指导,并进一步完善外浮顶罐蒸发损耗评价理论体系。
It is important to reveal the mechanism and law of oil vapor leakage and diffusion of external floating-roof tank(EFRT) to ensure the tank farm safety and reduce the environmental pollution. In present paper, numerical simulation and experimental verification were carried out for the oil vapor leakage and diffusion of large and small EFRT at different leak locations and pore sizes. The results were as follows. ① When the wind blows to the EFRT, a large scale eddy will form above the floating deck and form a symmetrical distribution of air flow from the downwind side to the upper wind side. ② When a pore leak occurs above the floating deck, oil vapor is closely attached to the floating deck and moves from the downwind to the upwind side. Oil vapor is easy to spread out when the leakage positions of the floating deck are located in the middle or the downwind side, but it is easy to accumulate when the positions are on upwind side or both sides of the floating deck, and there is a great potential safety hazard. The increase of wind speed is beneficial to the diffusion of oil vapor, but it will enlarge the scope of pollution. ③ when there was a rim leakage between the floating deck and tank wall, oil vapor diffuses along the tank wall to the upper space of the floating deck, and the extent of diffusion is: the sides of the floating deck > the upper wind side > the downwind side. ④ For the central leakage pore of the floating deck, when the pore diameter is 20 mm, the volume fraction of n-heptane is between 0.1% and 1.7%, which is within the corresponding explosion limit range; however, when the pore diameter is 6 mm, the volume fraction of nheptane is between 0.02% and 0.26% and the volume fraction of gasoline vapor is between 0.05% and0.65%, which all are not up to the explosion limit range. Thus, the possibility of explosion danger increases with the enlargement of the pore diameter. The research results will further reveal the migration law of the mixture gas of the vapor-air above the floating deck and the mass transfer mechanism of oil vapor diffusion, which can provide theoretical guidance for field practice and oil tank management and improve the theoretical system for evaluating the EFRT evaporation loss.
It is important to reveal the mechanism and law of oil vapor leakage and diffusion of external floating-roof tank(EFRT) to ensure the tank farm safety and reduce the environmental pollution. In present paper, numerical simulation and experimental verification were carried out for the oil vapor leakage and diffusion of large and small EFRT at different leak locations and pore sizes. The results were as follows. ① When the wind blows to the EFRT, a large scale eddy will form above the floating deck and form a symmetrical distribution of air flow from the downwind side to the upper wind side. ② When a pore leak occurs above the floating deck, oil vapor is closely attached to the floating deck and moves from the downwind to the upwind side. Oil vapor is easy to spread out when the leakage positions of the floating deck are located in the middle or the downwind side, but it is easy to accumulate when the positions are on upwind side or both sides of the floating deck, and there is a great potential safety hazard. The increase of wind speed is beneficial to the diffusion of oil vapor, but it will enlarge the scope of pollution. ③ when there was a rim leakage between the floating deck and tank wall, oil vapor diffuses along the tank wall to the upper space of the floating deck, and the extent of diffusion is: the sides of the floating deck > the upper wind side > the downwind side. ④ For the central leakage pore of the floating deck, when the pore diameter is 20 mm, the volume fraction of n-heptane is between 0.1% and 1.7%, which is within the corresponding explosion limit range; however, when the pore diameter is 6 mm, the volume fraction of nheptane is between 0.02% and 0.26% and the volume fraction of gasoline vapor is between 0.05% and0.65%, which all are not up to the explosion limit range. Thus, the possibility of explosion danger increases with the enlargement of the pore diameter. The research results will further reveal the migration law of the mixture gas of the vapor-air above the floating deck and the mass transfer mechanism of oil vapor diffusion, which can provide theoretical guidance for field practice and oil tank management and improve the theoretical system for evaluating the EFRT evaporation loss.
引文
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[6]郑仕超.浮顶罐沉盘事故的原因分析及预防对策[J].石油化工安全环保技术,2007,23(6):24-26.ZHENG S C.Cause analysis and preventive measures for the sinking of floating roof[J].Petrochemical Safety and Environmental Protection Technology,2007,23(6):24-26.
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[12]宋贤生,刘全桢,宫宏,等.大型罐区油气扩散规律的CFD数值模拟研究[J].中国安全生产科学技术,2008,4(2):86-90.SONG X S,LIU Q Z,GONG H,et al.CFD numerical simulation of heavy gas dispersion in great tank areas[J].Journal of Safety Science and Technology,2008,4(2):86-90.
[13]HASSANVAND A,HASHEMABADI S H,BAYAT M.Evaluation of gasoline evaporation during the tank splash loading by CFD techniques[J].International Communications in Heat and Mass Transfer,2010,37(7):907-913.
[14]HASSANVAND A,HASHEMABADI S H.Direct numerical simulation of interphase mass transfer in gas-liquid multiphase systems[J].International Communications in Heat and Mass Transfer,2011,38(7):943-950.
[15]文建军,丁波.浮顶罐密封圈油气分布数值模拟[J].中国安全生产科学技术,2016,12(2):57-61.WEN J J,DING B.Numerical simulation on oil vapor distribution in seal ring of floating roof tank[J].Journal of Safety Science and Technology,2016,12(2):57-61.
[16]赵晨露,黄维秋,钟璟,等.外浮顶罐油气泄漏的数值模拟[J].化工学报,2014,65(10):4203-4209.ZHAO C L,HUANG W Q,ZHONG J,et al.Numerical simulation of oil vapor leakage from external floating-roof tank[J].CIESC Journal,2014,65(10):4203-4209.
[17]赵晨露,黄维秋,石莉,等.内浮顶罐中油气扩散运移的数值模拟[J].安全与环境学报,2015,15(3):72-77.ZHAO C L,HUANG W Q,SHI L,et al.Numerical simulation of the oil-vapor diffusion and its migration from the internal floating-roof tank[J].Journal of Safety and Environment,2015,15(3):72-77.
[18]曲文晶,张来斌,马庆春.液化石油气球罐泄漏扩散的数值模拟[J].安全与环境工程,2012,19(4):119-124.QU W J,ZHANG L B,MA Q C.Numerical simulation of LPGspherical tank's leakage diffusion[J].Safety and Environmental Engineering,2012,19(4):119-124.
[19]余彬彬,张赞牢,刘强,等.拱顶罐量油孔油气逸出及扩散数值模拟[J].后勤工程学院学报,2014,30(6):23-27.YU B B,ZHANG Z L,LIU Q,et al.Numerical simulation on oil vapor escape and diffusion from gauge hatch of dome roof tanks[J].Journal of Logistical Engineering University,2014,30(6):23-27.
[20]王福军.计算流体动力学分析:CFD软件原理与应用[M].北京:清华大学出版社,2004:7-12,113-126.WANG F U.Computational fluid dynamics analysis:the principle and application of CFD software[M].Beijing:Tsinghua University Press,2004:7-12,113-126.
[2]杨静怡,朱胜杰,陈鹏,等.外浮顶原油储罐VOCs泄漏损耗及排放量核算[J].安全、健康和环境,2017,17(5):37-40.YANG J Y,ZHU S J,CHEN P,et al.Leakage loss and emission calculation of VOCs in outer floating crude oil tank[J].Safety Health&Environment,2017,17(5):37-40.
[3]司海涛.大型浮顶罐主要安全事故类型及原因[J].油气储运,2013,32(9):1029-1033.SI H T.Accident's type and cause of large-scale floating roof tank[J].Oil&Gas Storage and Transportation,2013,32(9):1029-1033.
[4]吴长炼.30000m3外浮顶罐底板穿孔原因分析及修复[J].油气储运,2002,21(5):56-57.WU C L.Case analysis on the perforation of bottom plate of a 30000m3floating roof tank[J].Oil&Gas Storage and Transportation,2002,21(5):56-57.
[5]冯亮.大型外浮顶储罐密封装置存在问题分析及对策探讨[J].油气田地面工程,2017,36(12):79-83.FENG L.Analysis of existing problems and discussion of countermeasures for sealing devices of large-scale external floating roof tanks[J].Oil-Gas Field Surface Engineering,2017,36(12):79-83.
[6]郑仕超.浮顶罐沉盘事故的原因分析及预防对策[J].石油化工安全环保技术,2007,23(6):24-26.ZHENG S C.Cause analysis and preventive measures for the sinking of floating roof[J].Petrochemical Safety and Environmental Protection Technology,2007,23(6):24-26.
[7]WU C F,WU T G,HASHMONAY R A,et al.Measurement of fugitive volatile organic compound emissions from a petrochemical tank farm using open-path Fourier transform infrared spectrometry[J].Atmospheric Environment,2014,82:335-342.
[8]TAMADDONO M,GHAREBAGH R S,NARIO S,et al.Experimental study of the VOC emitted from crude oil tankers[J].Process Safety and Environmental Protection,2013,92(6):929-937.
[9]STAMOUDIS N,CHRYSSAKIS C,KAIKTSIS L.A two-component heavy fuel oil evaporation model for CFD studies in marine Diesel engines[J].Fuel,2014,115:145-153.
[10]ABIANEH O S,CHEN C P,MAHALINGAM S.Numerical modeling of multi component fuel spray evaporation process[J].International Journal of Heat and Mass Transfer,2014,69:44-53.
[11]KOUNTOURIOTIS A,ALEIFERIS P G,CHARALAMBIDES A G.Numerical investigation of VOC levels in the area of petrol stations[J].Science of the Total Environment,2014,470:1205-1224.
[12]宋贤生,刘全桢,宫宏,等.大型罐区油气扩散规律的CFD数值模拟研究[J].中国安全生产科学技术,2008,4(2):86-90.SONG X S,LIU Q Z,GONG H,et al.CFD numerical simulation of heavy gas dispersion in great tank areas[J].Journal of Safety Science and Technology,2008,4(2):86-90.
[13]HASSANVAND A,HASHEMABADI S H,BAYAT M.Evaluation of gasoline evaporation during the tank splash loading by CFD techniques[J].International Communications in Heat and Mass Transfer,2010,37(7):907-913.
[14]HASSANVAND A,HASHEMABADI S H.Direct numerical simulation of interphase mass transfer in gas-liquid multiphase systems[J].International Communications in Heat and Mass Transfer,2011,38(7):943-950.
[15]文建军,丁波.浮顶罐密封圈油气分布数值模拟[J].中国安全生产科学技术,2016,12(2):57-61.WEN J J,DING B.Numerical simulation on oil vapor distribution in seal ring of floating roof tank[J].Journal of Safety Science and Technology,2016,12(2):57-61.
[16]赵晨露,黄维秋,钟璟,等.外浮顶罐油气泄漏的数值模拟[J].化工学报,2014,65(10):4203-4209.ZHAO C L,HUANG W Q,ZHONG J,et al.Numerical simulation of oil vapor leakage from external floating-roof tank[J].CIESC Journal,2014,65(10):4203-4209.
[17]赵晨露,黄维秋,石莉,等.内浮顶罐中油气扩散运移的数值模拟[J].安全与环境学报,2015,15(3):72-77.ZHAO C L,HUANG W Q,SHI L,et al.Numerical simulation of the oil-vapor diffusion and its migration from the internal floating-roof tank[J].Journal of Safety and Environment,2015,15(3):72-77.
[18]曲文晶,张来斌,马庆春.液化石油气球罐泄漏扩散的数值模拟[J].安全与环境工程,2012,19(4):119-124.QU W J,ZHANG L B,MA Q C.Numerical simulation of LPGspherical tank's leakage diffusion[J].Safety and Environmental Engineering,2012,19(4):119-124.
[19]余彬彬,张赞牢,刘强,等.拱顶罐量油孔油气逸出及扩散数值模拟[J].后勤工程学院学报,2014,30(6):23-27.YU B B,ZHANG Z L,LIU Q,et al.Numerical simulation on oil vapor escape and diffusion from gauge hatch of dome roof tanks[J].Journal of Logistical Engineering University,2014,30(6):23-27.
[20]王福军.计算流体动力学分析:CFD软件原理与应用[M].北京:清华大学出版社,2004:7-12,113-126.WANG F U.Computational fluid dynamics analysis:the principle and application of CFD software[M].Beijing:Tsinghua University Press,2004:7-12,113-126.