罐区环境下氨气泄漏扩散特性及事故后果研究
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摘要
从气体扩散机理出发,以特定事故罐区为环境,设定氨气泄漏位置为储罐封头上接管处,应用CFD研究意外泄漏后氨气浓度场、速度场的变化情况,并根据模拟结果对氨气意外泄漏的危险区域范围进行预测。结果表明,障碍物两侧和顶部流场速度有明显提升,迎风面和背风面速度降低,背风面易形成气体堆积;氨气初始泄漏阶段范围较小,进入流场后初始动量迅速消耗,进入气云扩散阶段;氨气气云横向扩散速度稳定,顺风向速度与风速基本相同,气云爬升受障碍物影响较大;氨气扩散时,危险浓度范围宽广,但致死浓度区域和燃爆性区域均较小。
Based on the gas diffusion mechanism, taking certain tank area as example, setting the leakage spot at tube joint of tank capped end, the flow distribution of the region, the variation law of ammonia concentration field with time after ammonia gas accidental leakage in a specific tank area were studied by CFD software, and dangerous areas were predicted according to the simulation results. The results indicated that the velocity of the flow field on both sides and top of the obstacle is improved obviously, and the velocities at the windward and the leeward sides are decrease and ammonia is easy to accumulate at the leeward sides. Both time and area of ammonia's initial leakage stage are small, and after entering the flow field, the initial momentum of ammonia is consumed rapidly and enters the gas cloud diffusion stage. The lateral diffusion rate of ammonia cloud is stable, the downwind speed of ammonia cloud is nearly the same as wind speed, and the situation of gas cloud climbing is obviously affected by obstacle. Once ammonia accidental leak occurs, the range of diffusion is greater, but the lethal concentration area and the explosive area are small.
Based on the gas diffusion mechanism, taking certain tank area as example, setting the leakage spot at tube joint of tank capped end, the flow distribution of the region, the variation law of ammonia concentration field with time after ammonia gas accidental leakage in a specific tank area were studied by CFD software, and dangerous areas were predicted according to the simulation results. The results indicated that the velocity of the flow field on both sides and top of the obstacle is improved obviously, and the velocities at the windward and the leeward sides are decrease and ammonia is easy to accumulate at the leeward sides. Both time and area of ammonia's initial leakage stage are small, and after entering the flow field, the initial momentum of ammonia is consumed rapidly and enters the gas cloud diffusion stage. The lateral diffusion rate of ammonia cloud is stable, the downwind speed of ammonia cloud is nearly the same as wind speed, and the situation of gas cloud climbing is obviously affected by obstacle. Once ammonia accidental leak occurs, the range of diffusion is greater, but the lethal concentration area and the explosive area are small.
引文
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[2]杜喜臣,蔡敏琦.液氨泄漏事故树分析及风险预测[J].环境工程学报,2008,2(10):1430-1432.
[3]谭蔚,刘潇,刘玉金.危险液化气体瞬时泄漏扩散数值模拟研究进展[J].化学工程,2012,(5):46-49.
[4]AKHATOVA A.CFD simulation of the dispersion of exhaust gases in a traffic-loaded street of Astana,Kazakhstan[J].Journal of Urban and Environmental Engineering,2015,9(2):158-166.
[5]CHENG C,TAN W,LIU L.Numerical simulation of water curtain application for ammonia release dispersion[J].Journal of Loss Prevention in the Process Industries,2014,30(1):105-112.
[6]潘旭海,蒋军成.重气云团瞬时泄漏扩散的数值模拟研究[J].化学工程,2003,31(1):35-39.
[7]江南,陈玉明.结合Fluent的液氨泄漏扩散模拟及中毒定量评估[J].甘肃科学学报,2016,(6):69-72.
[8]吴其荣,杜云贵,喻江涛,等.火电厂氨泄漏扩散特性模拟研究[J].环境科学与技术,2014,(2):155-159.
[9]TAN W,DU H,LIU L,et al.Experimental and numerical study of Ammonia leakage and dispersion in a food factory[J].J.Loss Prevent Proc.,2017,47:129-139.
[10]于建国,沈艳涛.研究简报有毒有害气体泄漏的Cfd数值模拟(I)模型建立与校验[J].化工学报,2007,3(58):745-749.
[11]YAKHOT V,ORSZAG S A.Renormalization group analysis of turbulence.I.Basic theory[J].Journal of Scientific Computing,1986,1(1):3-51.
[12]SPEZIALE C G,GATSKI T B,FITZMAURICE N.An analysis of RNG based turbulence models for homogeneous shear flow[J].Phys Fluids A(Fluid Dynamics),1991,3(9):2278-2281.
[13]SPEZIALE C G,THANGAM S.Analysis of an RNG based turbulence model for separated flows[J].Int.J.Eng.Sci,1992,30(10):1379-1388.
[14]LAKEHAL D.Computation of turbulent shear flows over roughwalled circular cylinders[J].Journal of Wind Engineering&Industrial Aerodynamics,1999,80(1):47-68.
[15]庄学强.大型液化天然气储罐泄漏扩散数值模拟[D].武汉:武汉理工大学,2012.
[16]GBZ 1-2010,工业企业设计卫生标准[S].