热油管道停输降温过程的数值计算
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摘要
研究热油管道的停输降温过程,对确定安全停输时间、提出再启动方案以及制订停输检修计划具有重要的指导作用。本文利用FLUENT软件进行数值计算,找到了一种更为简单的求解热油管道停输降温问题的方法,即将油温低于临界温度(比反常点温度低3℃)的原油粘度增至足够大,且当管内壁上顶点温度等于临界温度时,在软件设置中进行关闭重力选项等一系列操作。该方法不需要跟踪析蜡过程中固液相界面的移动,并且将析蜡潜热转化成了附加比热容来考虑。在此基础上,又计算了冬季华东地区不同敷设条件管道的停输降温过程。发现:对于水下管道,在其他条件相同时,要延长其降温时间,增大管径比提高初始油温更有效;对于架空管道,由于管道与大气间的换热系数很小,使得其降温速度与初始油温相同的水下管道基本一致,而且在计算时还可以忽略气温的昼夜变化;对于埋地管道,由于管外降温影响区的大小随停输时间的延长而逐渐增大,使得管内原油降温速度明显减慢。当管外土壤物性均匀一致时,初始油温的高低对降温影响区的大小没有影响。还发现,将土壤矩形求解区域适当地减小,可以在减少计算量的同时仍能保证计算结果的正确性。研究管道停输过程中管内原油温度分布随时间的变化,发现,停输初始阶段由于自然对流的作用而上升至管道上部的高温区随停输时间的延长会逐渐下移,水下和架空管道的高温区最终下移至管道中心,而埋地管道的则将下移至管道下部。
It is important to research the temperature drop process of hot oil pipeline for guiding the fixing of safely shutdown time, proposing restart scheme and making maintenance plan. A more easy method for solving temperature drop problem of hot oil pipeline was found in this paper by doing numerical calculation with the FLUENT software. During the calculating process, increase the viscosity of crude oil whose temperature was lower than the critical temperature (lower than anomalistic point temperature by 3℃) to enough, and change some correlated software settings when the temperature of upper peak inside pipe wall is equal to the critical temperature. This method does not need to follow the moving of phase interface in the wax precipitation process and invert the latent heat to heat absorption capacity additive. Based on this, temperature drop processes in winter of different laying conditions pipelines in Hua Dong area were calculated. The results shows that, for underwater pipeline, increasing the pipe diameter is more valid to prolong temperature drop time than raising initial oil temperature while other conditions are the same; for overhead pipeline, as the heat exchange factor is small, the temperature drop velocity of this pipeline is nearly equal to that of underwater pipeline, and the diurnal variation of air temperature can be ignored when calculated; for buried pipeline, the oil temperature drop velocity is slow down obviously because of the increase of temperature drop influence zone with the prolong of shutdown time, and the initial oil temperature has no effect on the size of influence zone if the soil properties are well-proportioned. In addition, decreasing the soil rectangle solving area properly can reduce the calculated amount while ensure the results exactitude. The oil temperature distribution during shutdown process was studied, and found that, with the prolong of shutdown time, high temperature area which lies upper inside the pipe as the result of natural convection after shutdown would move adown gradually, and at last to the pipe center for underwater and overhead pipe, but the lower part inside pipe for buried pipeline.
It is important to research the temperature drop process of hot oil pipeline for guiding the fixing of safely shutdown time, proposing restart scheme and making maintenance plan. A more easy method for solving temperature drop problem of hot oil pipeline was found in this paper by doing numerical calculation with the FLUENT software. During the calculating process, increase the viscosity of crude oil whose temperature was lower than the critical temperature (lower than anomalistic point temperature by 3℃) to enough, and change some correlated software settings when the temperature of upper peak inside pipe wall is equal to the critical temperature. This method does not need to follow the moving of phase interface in the wax precipitation process and invert the latent heat to heat absorption capacity additive. Based on this, temperature drop processes in winter of different laying conditions pipelines in Hua Dong area were calculated. The results shows that, for underwater pipeline, increasing the pipe diameter is more valid to prolong temperature drop time than raising initial oil temperature while other conditions are the same; for overhead pipeline, as the heat exchange factor is small, the temperature drop velocity of this pipeline is nearly equal to that of underwater pipeline, and the diurnal variation of air temperature can be ignored when calculated; for buried pipeline, the oil temperature drop velocity is slow down obviously because of the increase of temperature drop influence zone with the prolong of shutdown time, and the initial oil temperature has no effect on the size of influence zone if the soil properties are well-proportioned. In addition, decreasing the soil rectangle solving area properly can reduce the calculated amount while ensure the results exactitude. The oil temperature distribution during shutdown process was studied, and found that, with the prolong of shutdown time, high temperature area which lies upper inside the pipe as the result of natural convection after shutdown would move adown gradually, and at last to the pipe center for underwater and overhead pipe, but the lower part inside pipe for buried pipeline.
引文
[1] 杨筱衡,张国忠.输油管道设计与管理[M].东营:石油大学出版社,1996
[2] 阿卡帕金·B M.原油和油品管道的热力与水力计算[M].罗塘湖译.北京:石油工业出版社,1986
[3] 崔秀国,张劲军.埋地热含蜡原油管道的非稳态传热问题.中国工程科学,2003,5(7):77~82
[4] 李伟,张劲军.埋地含蜡原油管道温降规律.油气储运,2004,23(1):4~8
[5] 李才,刘云龙,苏仲勋.管内含蜡原油过程中的放热问题.油田地面工程,1994,13(1):18~20
[6] 汤楷孙,李才,安家荣等.海上高含蜡原油保温管道停输降温和再启动压力规律的研究(研究报告).石油大学储运教研室,1990,9
[7] 古宾.高粘高凝原油和成品油管道输送.陈祖泽译.北京:石油工业出版社,1987
[8] 安家荣,李才,刘云龙.水下和架空原油管道停输降温规律研究.石油大学学报(自然科学版)1995,4(19):70~73
[9] 菱田干雄,长野靖尚,孙元.水平管内高普朗特数流体的凝固[J].石油学报,1985,6(4):87～99
[10] 李长俊,纪国富,王元春.加热原油管道停输热力计算.西南石油学院学报,2000,22 (2):84~88
[11] 邢晓凯,张国忠.埋地热油管道停输与再启动过程研究.石油规划设计,2000,12(3):21~23
[12] 张国忠.埋地热油管道停输降温过程的研究.油气储运,2004,23(12)33~37
[13] A. M. Elsharkawy,T. A. Al-Sahhaf,M. A. Fahim. Wax deposition from Middle East crudes Fuel,2000(79):1047~1055
[14] H.-Y. Ji, B.Tohidi, A. Danesh,et al. Wax phase equilibria:developing a thermodynamic model using a systematic approach. Fluid Phase Equilibria, 2004(216):201~217
[15] P. Leelavanichkul,M.D. Deo.,F.V. Hanson. Crude oil characterization and regular solution approach to thermodynamic modeling of solid precipitation at low pressure. Petrol. Sci. Technol, 2004(22):973~990
[16] Wuhua Chen, Zongchang Zhao,Xiaodong Zhang,et al. Thermodynamic phase equilibria of wax precipitation in crude oils. Fluid Phase Equilibria,2007(255):31~36
[17] 许康,张劲军.采用焓法方程计算埋地管道含蜡原油停输降温.石油大学学报(自然科学版),2005,29(1):84~88
[18] 卢涛,孙军生,姜培学.架空原油管道停输期间温降及原油凝固界面推进.石油化工高等学校学报,2005,18(4):54~56
[19] 卢涛,姜培学.埋地原油管道停输期间温降及原油凝固传热模型及数值模拟.热科学与技术,2005,4(4):298~302
[20] 孔祥谦.有限单元法在传热学中的应用(第三版)[M].北京:科学出版社,1998
[21] 罗哲明,李传宪.原油流变性及测量.东营:石油大学出版社,1994
[22] 安家荣,植树培.采用探针法测量热油管道周围土壤温度场.油气储运,1998,17(8):41~43
[23] 蒋洪,朱聪,雷利.土壤导热系数法测定魏荆输油管道总传热系数.油气储运,2006,25(6):48～51
[24] Antuan N.,Mehmet A. H., Robert A. H.. Three-dimensional transient heat transfer from a buried pipe-I: laminar[J]. Chemical Engineering Science,1993,48(20):3507～3517
[25] Mehmet A. H., Antoine N., Robert A. H.. Three-dimensional transient heat transfer from a buried pipe-Ⅲ : comprehensive model [J]. Chemical Engineering Science,1995,50(16):2545～2555
[26] Mehmet A. H., Ali. A. H.. Freezing time predictions of buried pipes: A 3-D transient simulation [J]. Chemical Engineering Technology,1996 (19):243～248
[27] 姜笃志.输油管道非稳态热力过程数值分析[J].油气储运,1996,15 (8):1～5
[28] HAIM. H. B. Heat losses from a fluid flowing in a buried pipe[J]. Heat Mass Transfer,1982,25(11):1621～1629
[29] Himasek H.,Haim H. B.. Thermal convection associated with hot/cold pipes buried in a semi-infinite,saturated,porous medium [J]. Int. J Heat Mass Transfer,1987,30(2):263～273
[30] Chung M, et al. Semi-analytical solution for heat transfer from a buried pipe with convection on the exposed surface [J]. Heat Mass Transfer, 1999(42) :3771～3786
[31] 吴国忠,庞丽萍,卢丽冰等.埋地输油管道非稳态热力计算模型研究.油气田地面工程,2002,21(1):92~93
[32] 张静,吴明.用有限元法计算埋地热油管道土壤温度场.辽宁石油化工大学学报,2004,24(2):38~40
[33] Rosalind A. A., Michael J.O.. Models for heat transfer from a buried pipe [J]. SPE Journal, 1997(2):186～193
[34] 吴国忠,庞丽萍,卢丽冰等.埋地输油管道热力计算求解结果分析.油气地面工程,2001,20 (2):1~2
[35] 吴国忠,曲洪权.埋地输油管道非稳态热力计算数值求解方法.油气田地面工程,2001,20(6) :6~7
[36] 刘晓燕,庞丽萍,王振.庆哈埋地管道允许停输时间的计算.油气储运,2003,22(5):18～21
[37] 崔秀国,张劲军.埋地热油管道稳定运行条件下热力影响区的确定.石油大学学报(自然科学版),2004,28(2):75~78
[38] 卢涛,佟德斌.饱和含水土壤埋地原油管道冬季停输降温.北京化工大学学报,2006,33(4):37~40
[39] 王福军.计算流体动力学分析——CFD软件原理与应用.清华大学出版社,2004
[40] 张国忠.埋地热油管道准周期运行温度研究.油气储运,2001,20(6):4~7
[41] 李伟,张劲军.埋地热油管道停输后周围土壤温度场的数值模拟.西安石油大学学报(自然科学版),2005,20(6):27~33
[2] 阿卡帕金·B M.原油和油品管道的热力与水力计算[M].罗塘湖译.北京:石油工业出版社,1986
[3] 崔秀国,张劲军.埋地热含蜡原油管道的非稳态传热问题.中国工程科学,2003,5(7):77~82
[4] 李伟,张劲军.埋地含蜡原油管道温降规律.油气储运,2004,23(1):4~8
[5] 李才,刘云龙,苏仲勋.管内含蜡原油过程中的放热问题.油田地面工程,1994,13(1):18~20
[6] 汤楷孙,李才,安家荣等.海上高含蜡原油保温管道停输降温和再启动压力规律的研究(研究报告).石油大学储运教研室,1990,9
[7] 古宾.高粘高凝原油和成品油管道输送.陈祖泽译.北京:石油工业出版社,1987
[8] 安家荣,李才,刘云龙.水下和架空原油管道停输降温规律研究.石油大学学报(自然科学版)1995,4(19):70~73
[9] 菱田干雄,长野靖尚,孙元.水平管内高普朗特数流体的凝固[J].石油学报,1985,6(4):87～99
[10] 李长俊,纪国富,王元春.加热原油管道停输热力计算.西南石油学院学报,2000,22 (2):84~88
[11] 邢晓凯,张国忠.埋地热油管道停输与再启动过程研究.石油规划设计,2000,12(3):21~23
[12] 张国忠.埋地热油管道停输降温过程的研究.油气储运,2004,23(12)33~37
[13] A. M. Elsharkawy,T. A. Al-Sahhaf,M. A. Fahim. Wax deposition from Middle East crudes Fuel,2000(79):1047~1055
[14] H.-Y. Ji, B.Tohidi, A. Danesh,et al. Wax phase equilibria:developing a thermodynamic model using a systematic approach. Fluid Phase Equilibria, 2004(216):201~217
[15] P. Leelavanichkul,M.D. Deo.,F.V. Hanson. Crude oil characterization and regular solution approach to thermodynamic modeling of solid precipitation at low pressure. Petrol. Sci. Technol, 2004(22):973~990
[16] Wuhua Chen, Zongchang Zhao,Xiaodong Zhang,et al. Thermodynamic phase equilibria of wax precipitation in crude oils. Fluid Phase Equilibria,2007(255):31~36
[17] 许康,张劲军.采用焓法方程计算埋地管道含蜡原油停输降温.石油大学学报(自然科学版),2005,29(1):84~88
[18] 卢涛,孙军生,姜培学.架空原油管道停输期间温降及原油凝固界面推进.石油化工高等学校学报,2005,18(4):54~56
[19] 卢涛,姜培学.埋地原油管道停输期间温降及原油凝固传热模型及数值模拟.热科学与技术,2005,4(4):298~302
[20] 孔祥谦.有限单元法在传热学中的应用(第三版)[M].北京:科学出版社,1998
[21] 罗哲明,李传宪.原油流变性及测量.东营:石油大学出版社,1994
[22] 安家荣,植树培.采用探针法测量热油管道周围土壤温度场.油气储运,1998,17(8):41~43
[23] 蒋洪,朱聪,雷利.土壤导热系数法测定魏荆输油管道总传热系数.油气储运,2006,25(6):48～51
[24] Antuan N.,Mehmet A. H., Robert A. H.. Three-dimensional transient heat transfer from a buried pipe-I: laminar[J]. Chemical Engineering Science,1993,48(20):3507～3517
[25] Mehmet A. H., Antoine N., Robert A. H.. Three-dimensional transient heat transfer from a buried pipe-Ⅲ : comprehensive model [J]. Chemical Engineering Science,1995,50(16):2545～2555
[26] Mehmet A. H., Ali. A. H.. Freezing time predictions of buried pipes: A 3-D transient simulation [J]. Chemical Engineering Technology,1996 (19):243～248
[27] 姜笃志.输油管道非稳态热力过程数值分析[J].油气储运,1996,15 (8):1～5
[28] HAIM. H. B. Heat losses from a fluid flowing in a buried pipe[J]. Heat Mass Transfer,1982,25(11):1621～1629
[29] Himasek H.,Haim H. B.. Thermal convection associated with hot/cold pipes buried in a semi-infinite,saturated,porous medium [J]. Int. J Heat Mass Transfer,1987,30(2):263～273
[30] Chung M, et al. Semi-analytical solution for heat transfer from a buried pipe with convection on the exposed surface [J]. Heat Mass Transfer, 1999(42) :3771～3786
[31] 吴国忠,庞丽萍,卢丽冰等.埋地输油管道非稳态热力计算模型研究.油气田地面工程,2002,21(1):92~93
[32] 张静,吴明.用有限元法计算埋地热油管道土壤温度场.辽宁石油化工大学学报,2004,24(2):38~40
[33] Rosalind A. A., Michael J.O.. Models for heat transfer from a buried pipe [J]. SPE Journal, 1997(2):186～193
[34] 吴国忠,庞丽萍,卢丽冰等.埋地输油管道热力计算求解结果分析.油气地面工程,2001,20 (2):1~2
[35] 吴国忠,曲洪权.埋地输油管道非稳态热力计算数值求解方法.油气田地面工程,2001,20(6) :6~7
[36] 刘晓燕,庞丽萍,王振.庆哈埋地管道允许停输时间的计算.油气储运,2003,22(5):18～21
[37] 崔秀国,张劲军.埋地热油管道稳定运行条件下热力影响区的确定.石油大学学报(自然科学版),2004,28(2):75~78
[38] 卢涛,佟德斌.饱和含水土壤埋地原油管道冬季停输降温.北京化工大学学报,2006,33(4):37~40
[39] 王福军.计算流体动力学分析——CFD软件原理与应用.清华大学出版社,2004
[40] 张国忠.埋地热油管道准周期运行温度研究.油气储运,2001,20(6):4~7
[41] 李伟,张劲军.埋地热油管道停输后周围土壤温度场的数值模拟.西安石油大学学报(自然科学版),2005,20(6):27~33