CF_3H熄灭CH_4/O_2火焰过程中产生HF的数值研究
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摘要
三氟甲烷(CF_3H,HFC-23)是一种优良的哈龙替代物,在目前的气体灭火介质市场占据显著的位置。然而,在三氟甲烷和火焰作用的过程中产生的HF不仅对火灾现场设备具有严重的腐蚀,而且对灭火现场人员具有严重的伤害。首先采用κ-ε涡黏湍流模型,对CF_3H熄灭CH_4/O_2的二维稳态湍流非预混燃烧进行数值分析,讨论杯式燃烧器中CF_3H熄灭CH_4/O_2火焰过程中HF组分变化规律,通过改变初始参数分析CF_3H浓度、CH_4/O_2配比对HF生成量的影响;采用CHEMKIN 4.0程序模拟CF_3H熄灭CH_4/O_2火焰中温度、反应物、主产物和自由基浓度随火焰高度的变化关系。结果表明,火焰上方20～25cm的区域为HF富集区;H、CF:O为生成HF的重要中间产物,可以通过降低中间产物浓度降低HF。
This article is to present our study on reactions kinetics of HF formation during extinguishing fire by using CF_3H.To know the case that trifluoromethane(CF_3H,HFC-23),as one of important perfluoroalkanes,is used commonly in fire extinguishing agent market. However,when CF_3H is discharged into the fire protection place,HF will be produced by the interaction between the flame and CF_3H.HF not only has severe erosion to the metal apparatus,but also makes serious harm to the people in fire scene,so the production amount of HF in fire extinguishing protection is an important problem when CF_3H is applied.At present,there is lacking of in-depth insight of HF production in fire extinguishing process with CF_3H.In our study,detailed chemical kinetics and turbulent flow coupling method is applied to deal with mechanism of HF formation in Cup-burner. Firstly,κ-ε eddy viscosity turbulence model is employed to carry out the calculation on the two-dimensional steady state non-premixed combustion CH_4/O_2 fire with CF_3H;secondly,the HF formation influencing factors are discussed based on changing initial parameters, such as the CF_3H initial concentration or CH_4 initial concentration, while the rest parameters remain invariant;thirdly,in order to study the HF formation inner CF_3H/CH_4/O_2 flame,CHEMKIN 4.0 program is utilized to analyze temperature,reactant,the main product and free radical concentration with the variation of flame height.Conclusion: the rich HF height is 20 cm above the flame;H,CF:O is the key intermediate product during HF formation,so HF can be reduced by lowering the concentration of intermediate products H, CF:O.the research provides some references for developing new clean extinguishing media.
This article is to present our study on reactions kinetics of HF formation during extinguishing fire by using CF_3H.To know the case that trifluoromethane(CF_3H,HFC-23),as one of important perfluoroalkanes,is used commonly in fire extinguishing agent market. However,when CF_3H is discharged into the fire protection place,HF will be produced by the interaction between the flame and CF_3H.HF not only has severe erosion to the metal apparatus,but also makes serious harm to the people in fire scene,so the production amount of HF in fire extinguishing protection is an important problem when CF_3H is applied.At present,there is lacking of in-depth insight of HF production in fire extinguishing process with CF_3H.In our study,detailed chemical kinetics and turbulent flow coupling method is applied to deal with mechanism of HF formation in Cup-burner. Firstly,κ-ε eddy viscosity turbulence model is employed to carry out the calculation on the two-dimensional steady state non-premixed combustion CH_4/O_2 fire with CF_3H;secondly,the HF formation influencing factors are discussed based on changing initial parameters, such as the CF_3H initial concentration or CH_4 initial concentration, while the rest parameters remain invariant;thirdly,in order to study the HF formation inner CF_3H/CH_4/O_2 flame,CHEMKIN 4.0 program is utilized to analyze temperature,reactant,the main product and free radical concentration with the variation of flame height.Conclusion: the rich HF height is 20 cm above the flame;H,CF:O is the key intermediate product during HF formation,so HF can be reduced by lowering the concentration of intermediate products H, CF:O.the research provides some references for developing new clean extinguishing media.
引文
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[21] SASO Y,ZHU D L,WANG H,et al.Laminar burning velocities of trifluoromethane-methane mixtures:experiment and numerical simulation[J].Combustion and Flame,1998,114(3/4) :457-468．
[22] BURGESS J D R,ZACHARIAH M R,TSANG W,et al.Thermochemical and chemical kinetic data for fluorinated hydrocarbons[J].Progress in Energy and Combustion Science,1996,21:453-529．
[23] DONG Gang(董刚),JIANG Yong(蒋勇),CHEN Yiliang(陈义良),et al.A large-scale gas-phase chemical kinetics software package chemkin and its application in combustion problems[J].Fire Safety Science(火灾科学),2000,9(1) :27-33．
[24] BRADY B B,MARTIN L R.Use of surface chemkin to model multiphase atmospheric chemistry:application to nitrogen tetroxide spills[J].Atmospheric Environment,1995,29(6) :715-726．
[25] SAFTA C,MADNIA C K.Autoignition and structure of nonpremixed CH_4/H_2 flames:detailed and reduced kinetic models[J].Combustion and Flame,2006,144(1/2) :64-73．
[26] DONG Gang(董刚),LIU Hongwei(刘宏伟),CHEN Yiliang(陈义良).General, nitrogen-containing semi-detailed chemical kinetic mechanism for methane laminar premixed flame[J].Journal of Combustion Science and Technology(燃烧科学与技术),2002,8(1) :44-49．
[27] ATKINSON R,BAULCH D L,COX R A,et al.Evaluated kinetic and photochemical data for atmospheric chemistry:volume Ⅳ-gas phase reactions of organic halogen species[J].Atmospheric Chemistry and Physics,2008,8:4144-4496．
[2] MCCULLOCH A.CFC and Halon replacements in the environment[J].Journal of Fluorine Chemistry,1999,100(1/2) :163-173．
[3] VANDOORENA J,NELSON D C F,VAN TIGGELEN P J,et al.The inhibiting effect of CF_3H on the structure of a stoichiometric H_2/CO/O_2/Ar flame[J].Symposium (International) on Combustion,1989,22(1) :1587-1595．
[4] LAITINEN J,MAKELA M,MIKKOLA J,et al.Fire fighting trainers' exposure to carcinogenic agents in smoke diving simulators[J].Toxicology Letters,2010,192(1) :61-65．
[5] PAUL K T,HULL T R,LEBEK K,et al.Fire smoke toxicity:the effect of nitrogen oxides[J].Fire Safety Journal,2008,43(4) :243-251．
[6] LESTARI F,GREEN A R,CHATTOPADHYAY G,et al.An alternative method for fire smoke toxicity assessment using human lung cells[J].Fire Safety Journal,2006,41(8) :605-615．
[7] STAVERT D M,ARCHULETA D C,BEHR M J,et al.Relative acute toxicities of hydrogen fluoride,hydrogen chloride,and hydrogen bromide in nose-and pseudo-mouth-breathing rats[J J.Fundamental and Applied Toxicology,1991,16(4) :636-655．
[8] BANKS R E,CLARKE E K,JOHNSON E P,et al.Environmental aspects of fluorinated materials:part 31:comparative life-cycle assessment of the impacts associated with fire extinguishants HFC-227ea and IG-541[J].Process Safety and Environmental Protection,1998,76(3) :229-238．
[9] CONG Beihua(丛北华),QI Fei(齐飞),LIAO Guanxuan(廖光煊),et al.Experimental study on inhibition of low pressure premixed flat methane-oxygen flames by trifluoromethane[J].Chinse Science Bulletion(科学通报),2005,50(16) :1789-1793．
[10] LINTERIS G T,GMURCZYK G W.Fire suppression system performance of alternative agents in aircraft engine and dry bay laboratory simulationsp,NIST SP 890[R].Washington D C:National Institute of Standards and Technology,1995:201-318．
[11] LINTERIS G T.Numerically predicted structure and burning velocity of premixed CO-Ar-O_2-H_2 flames inhibited by CF_3H[J].Combustion and Flame,1996,107(1/2) :72-84．
[12] KATTA V R,TAKAHASHI F,LINTERIS G T.Fire-suppression characteristics of CF_3H in a cup burner[J].Combustion and Flame,2006,144(4) :645-661．
[13] JIANG Yong(蒋勇).Numerical predictions of premixed flame struc- ture for hydrocarbon /air coupling detailed chemical kinetics[J].Journal of Jiangs u University:Natural Science(江苏大学学报:自然科学版),2002,23(2) :22-25．
[14] LI Ming(李铭),WANG Wangang(王万钢).Determination of flame-extinguishing concentration of gaseous extinguishants by the cup burner method[J].Fire Science and Technology(消防科学与技术),2005,24(2) :218-219．
[15] LINTERIS G T,KATTA V R,TAKAHASHI F.Experimental and numerical evaluation of metallic compounds for suppressing cup-burner flames[J].Combustion and Flame,2004,138 (1/2) :78-96．
[16] GUO Zhiming(郭治明),ZHANG Huiqiang(张会强),WANG Xilin(王希麟).Numerical simulation of turbulent combustion using a presumed joint PDF model[J].Journal of Tsinghua University:Science and Technology(清华大学学报:自然科学版),2001,41(8) :75-78．
[17] PARENTE A,GALLETTI C,TOGNOTTI L.Effect of the combustion model and kinetic mechanism on the MILD combustion in an industrial burner fed with hydrogen enriched fuels[J].International Journal of Hydrogen Energy,2008,33(24) :7553-7564．
[18] LAU J H W.Comparison of pdf and eddy-dissipation combustion models applied to a propane jet flame[J].Combustion and Flame,1995,102(1/2) :209-215．
[19] CUI Yufeng(崔玉峰),XU Gang(徐纲),NIE Chaoqun(聂超群),et al.Application of numerical simulation in the design of gas turbine combustor for burning syngas[J].Proceedings of The Chinese Society for Electrical Engineering(中国电机工程学报),2006,26(16) :109117．
[20] ZHAO Jianxing(赵坚行).Numerical simulation of combustion(燃烧的数值模拟)[M].Beijing:Science Press,2002:114．
[21] SASO Y,ZHU D L,WANG H,et al.Laminar burning velocities of trifluoromethane-methane mixtures:experiment and numerical simulation[J].Combustion and Flame,1998,114(3/4) :457-468．
[22] BURGESS J D R,ZACHARIAH M R,TSANG W,et al.Thermochemical and chemical kinetic data for fluorinated hydrocarbons[J].Progress in Energy and Combustion Science,1996,21:453-529．
[23] DONG Gang(董刚),JIANG Yong(蒋勇),CHEN Yiliang(陈义良),et al.A large-scale gas-phase chemical kinetics software package chemkin and its application in combustion problems[J].Fire Safety Science(火灾科学),2000,9(1) :27-33．
[24] BRADY B B,MARTIN L R.Use of surface chemkin to model multiphase atmospheric chemistry:application to nitrogen tetroxide spills[J].Atmospheric Environment,1995,29(6) :715-726．
[25] SAFTA C,MADNIA C K.Autoignition and structure of nonpremixed CH_4/H_2 flames:detailed and reduced kinetic models[J].Combustion and Flame,2006,144(1/2) :64-73．
[26] DONG Gang(董刚),LIU Hongwei(刘宏伟),CHEN Yiliang(陈义良).General, nitrogen-containing semi-detailed chemical kinetic mechanism for methane laminar premixed flame[J].Journal of Combustion Science and Technology(燃烧科学与技术),2002,8(1) :44-49．
[27] ATKINSON R,BAULCH D L,COX R A,et al.Evaluated kinetic and photochemical data for atmospheric chemistry:volume Ⅳ-gas phase reactions of organic halogen species[J].Atmospheric Chemistry and Physics,2008,8:4144-4496．