摘要
超音速分离管天然气除湿净化技术较常规天然气处理技术有一系列的优点,如设备结构简单,占地面积小,重量轻,没有运动部件,无需消耗任何外部动力等。但是,为了保证超音速分离管具有良好的分离效果,必须了解来自井口的天然气在超音速分离管的关键部件——Laval喷管内部的超音速流动与凝结特性,揭示其影响因素,探索有效提高分离效率的技术途径。本文的研究目标在于揭示天然气在喷管内的凝结流动机理,采用理论与实验相结合的方法,综合应用非平衡热力学、气体动力学、传热传质学、两相流体动力学以及计算流体力学等相关理论对Laval喷管内的可压缩凝结性气体的流动过程进行较为系统全面的研究。
首先,根据喷管内水蒸气凝结过程,建立了喷管内水蒸气自发凝结模型,并与前人结果进行了对比,表明所建立的数学模型能够正确反映喷管内水蒸气超音速流动凝结参数的分布特征。利用所建立的数学模型研究了摩擦阻力、喷管膨胀率对水蒸气自发凝结过程的影响,结果表明,这两个参数对水蒸气的自发凝结过程都有明显而直接的影响。在此基础上,建立了非均相凝结流动过程的数学模型,研究了外界核心对水蒸气超音速流动的影响,证明:外界核心的存在对蒸汽的凝结有明显促进作用。
建立了喷管内双组份可凝结气体混合物超音速流动的数学模型,研究了氮气-水蒸气、甲烷-水蒸气、甲烷-壬烷在喷管内的超音速流动与凝结过程。结果发现,氮气-水蒸气在其它进口参数相同的条件下,入口压力、温度、过饱和度对极限过冷度、成核率、液滴数、液滴的平均半径和液相质量分数均有明显的影响;甲烷-水蒸气在喷管喉部之后(x=10.0 mm)过冷度很快上升到40K左右,达到Wilson点,蒸汽突然开始凝结,成核率从0急剧上升到1024量级,水滴数目急剧增加,同时释放出大量的凝结潜热加热周围气体,引起“凝结冲波”现象;甲烷-壬烷的过冷度沿喷管沿程不断增大到72K左右才发生凝结成核现象。由于液滴数量较少和壬烷潜热较小的原因,在压力和温度曲线上没有出现像甲烷-水蒸气发生自发凝结时那样明显的“凝结冲波”现象。
再后,建立了喷管内三组分可凝结气体混合物超音速流动的物理模型和数学模型,并对甲烷-水蒸气-壬烷在喷管内的超音速凝结过程进行了模拟研究。研究发现,水蒸气的存在,在一定意义上促进了壬烷蒸汽的凝结。通过对甲烷-水蒸气-壬烷在喷管内超音速流现象的理论分析研究,初步了解了井口天然气的相关凝结特性,为实现对井口天然气液滴成核与液滴生长的控制、提高超音速分离管的分离效率提供理论依据。
最后,搭建了用于压缩空气凝结特性测试的实验系统,并对湿空气的超音速流动及其凝结特性进行了实验研究并与理论模拟结果进行了比较。研究表明,非均相凝结模型与实验结果吻合较好;把湿空气在喷管内发生的凝结过程视为非均相凝结是比较合理的,也验证了所建立的非均相凝结模型。
Natural gas supersonic dehydration and purification technology is of a series of advantages over conventional natural gas treatment methods, such as very simple equipment structure, small in size, light in weight, no moving parts and needing no extra energy but the excess pressure of wells. However, in order to ensure the designed separation performance, it is of vital importance to understand the flow and condensation characteristics of natural gases in Laval nozzle which is the key part of the supersonic dehydration and purification system. The present work is aimed at understanding the flow and condensation characteristics of natural gases flowing through Laval nozzles. The main work is summarized as follows.
A spontaneous condensation mathematical model for supersonic flow with condensation of water vapor in Laval nozzles is developed. The numerical results of the model are compared with and the good agreement is obtained with the experimental data from literatures. The model was then extended to study the influences of friction drag and expansion rate on spontaneous condensation parameters of condensable water vapor flow through Laval nozzles. The results show that both the friction drag and the expansion rate have obvious and important influences on the flow and condensation characteristics. A numerical simulation was also performed for the water vapor supersonic flow in Laval nozzles with the existence of exoteric nuclei. It was found that the exoteric nuclei may significantly promote the water vapor condensation process.
A spontaneous condensation physical mathematical model for supersonic condensing flow of two-component gas mixtures (one non-condensable inert gas and condensable vapor) in Laval nozzles is established to study the supersonic flow and spontaneous condensation process of nitrogen-water, methane-water and methane-nonane mixtures. The obvious influences of inlet pressure, temperature and supersaturation were found from the simulation results of the nitrogen-water vapor flow process on extreme supercooling, nucleation rate, droplet number, droplet size and liquid phase fraction. For the methane-water vapor flow, the supercooling increases to 40K right after the throat of the nozzle (x=10.0mm), and the vapor begin to condense companying with a condensation shock and a heating effect to the flow from latent heat release, the nucleation rate quickly increases to 1024kg-1s-1. Nonane in the methane-nonane vapor mixture begins to condense as the supercooling increases to 72K. No obvious condensation shock can be observed of the methane-nonane vapor mixture flow, which may be well attributed to the fact that the latent heat and the quantity of the nonane condensed are much smaller than water vapor.
A mechanism and mathematical model is developed for the supersonic flow and spontaneous condensation process of three-component mixtures (one non-condensable insert gas plus two different condensable gases). And then the model is used to simulate the supersonic flow and condensation characteristics of methane-water vapor-nonane mixtures. It is found that the existence of water vapor is enhanced the condensation process of nonane vapor to some extent. The mechanism model and the simulation results are helpful for understanding the flow and condensation characteristics of natural gas, controlling the nucleation rate and/or droplet growth rate, and improving the separation efficiency of supersonic separators.
An experimental rig for testing the flow and condensation characteristics of wet air is set up, a series of experimental results are obtained. The simulation results from the previous physical and theoretical model are compared against the experimental results. It is found that the heterogeneous model can predict the experimental data of both pressure and droplet sizes.
引文
1 J. M. Prausnitz, R. N. Lichtenthaler, E. Gomes de Azevedo. Molecular Thermodynamics of Fluid-phase Equilibria. Prentice-Hall, New Jersey, 2nd edtion, 1986
2 P. J. Crutzen. In Nucleation and Atmospheric Aerosols, Pergamon, 1996: 268-270
3 K. N. H. Looijmans. Homogeneous Nucleation and Droplet Growth in the Coexistence Region of n-Alkane/Methane Mixture at High Pressure,Ph D. Dissertation, Eindhoven University of Technology, 1995
4 M. J. E. H. Muitjens. Homegeneous Condensation in a Vapor/Gas Mixture at High Pressure in an Expansion Cloud Chamber, Ph D. Dissertation, Eindhoven University of Technology, 1996
5 C. C. M. Luijten, Nucleation and Droplet Growth at High Pressure, Ph D. Dissertation, Eindhoven University of Technology, Eindhoven, The Netherlands, 1998
6 G. Lamanna. On Nucleation and Droplet Growth in Condensation Nozzle Flows,Ph D. Dissertation, Eindhoven University of Technology, 2000
7 P. Peeters. Nucleation and Condensation in Gas-Vapor Mixture of Alkanes and Water, Ph D. Dissertation, Eindhoven University of Technology, 2002
8 X. S. Luo. Unsteady Flows with Phase Transition, Ph D. Dissertation, Eindhoven University of Technology, 2004
9 M. J. Moore, C. H. Sieverding. Two-Phase Steam Flow in Turbine and Separators. New York: McGraw-Hill, 1976
10 M. J. Moore, C. H. Sieverding. Aerothermodynamics of Low Pressure Steam Turbines and Condensation. Hemisphere Publishing Corporation, 1986
11 A. Guha. Computation Analysis and Theory of Two-Phase Flows. The Aeronautical Journal, 1988, 102(1012):71-82
12王遇东.天然气处理与加工工艺.北京:石油工业出版社,1999
13朱利凯.天然气处理与加工.北京:石油工业出版社,1997
14诸林.天然气加工工程.北京:石油工业出版社,1996
15冯叔初.油气集输.东营:石油大学出版社,1995
16徐文渊,蒋长安.天然气利用手册.北京:中国石化出版社,2003
17龙晓达,肖锦堂.九十年代天然气处理加工利用技术进展.天研文集(十八).泸州,1998
18 F. Okimoto, J. M. Brouwer. Supersonic Gas Conditioning. World Oil. 2002, 223(8): 1170-1178
19 F. Okimoto, M. Betting, D. M. Page. Twister Supersonic Gas Conditioning. GPAPaper. 2001
20 B. V. Twister, F. M. C. Kongsberg, Subsea AS. Demonstration of Twister for Subsea Application. REP-0000021304. 2002
21何策,张晓东.国内外天然气脱水设备技术现状及发展趋势.石油机械,2008,36(2):69-73
22何策,程雁,额日其太.天然气超音速脱水技术评析.石油机械,2006,34(5):70-72
23王协琴,罗小米,孙玉梅.超音速分离器:天然气脱水脱烃的新型高效设备.天然气技术.2007,1(5):63-67,95
24 Twister Factssheet 1-How does Twister work,http://www.twisterbv.com
25 Twister the missing link for Subsea Processing, http://www.twisterbv.com
26 M. Betting, H. Epsom. Supersonic Separator Gains Market Acceptance. World Oil. 2007, (4): 197-200
27 Crook. Twist and Shout [Twister Supersonic Cyclonic Separator]. 2006, 782(8):
54-56
28 Brouwer, Epsom. Twister Supersonic Gas Conditioning for Unmanned Platforms and Subsea Gas Processing. Offshore Europe 2003 Oil and Gas Exhibition and Conference. Aberdeen, United Kingdom 2003: 219-225
29 H. W. Liu, Z. L. Liu, Y. X. Feng,et al. Characteristics of a Supersonic Swirling Dehydration System of Natural Gas. Chinese Journal of Chemical Engineering, 2005, 13(1): 9-12
30曹学文,陈丽,林宗虎等.超音速旋流天然气分离器研究.天然气工业,2007,
27(7):109-111
31曹学文,陈丽,林宗虎等.用于超声速旋流分离器中的超声速喷管研究.天然气工业,2007,27(7):112-114
32曹学文,陈丽,杜永军等.超声速旋流天然气分离器的旋流特性数值模拟.中国石油大学学报(自然科学版),2007,31(6):79-81,86
33曹学文,消荣鸽,杜永军等.喷管内高速流动天然气相变特性数值研究.西安石油大学学报(自然科学版).2008,23(1):56-60
34袁瑞华.高速气流实验型分离器的初步调研及设想.化工装备技术,2007,28(2):15-18
35康勇..新型天然气低温制冷脱水装置.油气储运,2007,26(3):32-34
36杨志毅..油气超音速旋流分离技术研究..西南石油学院博士学位论文,2004
37 http://202.118.65.214/news/zdsys.htm?id=36
38 http://www.3schina.com.cn/gsjj.asp
39 H. W. Liu, Z. L. Liu, Y. X. Feng, K. Y. Gu, T. M. Yan. A New Type of Dehydration Unit of Natural Gas and its Design Considerations. Progress in Natural Science, 2005, 15(12): 1148-1152
40刘恒伟,刘中良,冯永训,顾克宇,颜廷敏.新型湿空气除湿装置工作性能的实验研究.热科学与技术,2004,3(2):143-146
41刘恒伟,刘中良,张建,冯永训,颜廷敏.实际气体喷管喉部尺寸的设计计算.工程热物理学报.2006,5(27):862-864
42刘恒伟,刘中良,冯永训,顾克宇,颜廷敏.新型天然气超声波旋流脱水装置及其内部流动规律的理论分析解.北京工业大学学报.2006,9(32):829-832
43刘恒伟,刘中良,冯永训,顾克宇,颜廷敏.一种新型气液分离装置及其内部流动规律的理论分析解.工程热物理学会传热传质会议论文集.吉林,2004,1024-1027
44庞会中.新型超音速气体净化分离装置设计研究.北京工业大学硕士学位论文,2009
45刘恒伟.超音速分离管的研发及其流动与传热传质特性研究.北京工业大学博士学位论文,2006
46张远君,王慧玉,张振鹏编译.两相流体动力学基础理论及工程应用.北京:北京航空学院出版社,1987
47 F. F. Abraham. Homogeneous Nucleation Theory. Academic Press, 1974
48蔡颐年,王乃宁.湿蒸汽两相流.西安:西安交通大学出版社,1985
49 P. P. Wegener. Water Vapor Condensation Process in Supersonic Nozzles. J. Appl. Phys. 1954, 25: 1485-1491
50 F. Bakhtar, D. J. Ryley, K. A Tubman, et al. Nucleation Studies in Flowing High- Pressure Steam. Proc. IME. 1975, 189: 427-436
51 F. Bakhtar, M. T. Mohammadi Tochai. An Investigation of Two-Dimensional Flows of Nucleating and Wet Steam by the Time-Marching Method. Int. J. Heat & Fluid Flow. 1980, 2(1): 5-18
52俞茂铮,陈孝隆.存在自发凝结的超音速湿蒸汽双相流.西安交通大学学报.1983,17(1):23-32
53 D. Bolm, J. Ren. Salt Solution and Radius Dependence on Surface Tension in Heterogeneous Nucleation in Steam Turbines.中国工程热物理学会第十届年会论文集.青岛,2001
54李亮,丰镇平,李国君.平面叶栅中的湿蒸汽两相凝结流动数值模拟.工程热物理学报.2002,23(3):309-311
55巫志华,李亮,丰镇平.湿蒸汽两相流动问题的耦合求解.工程热物理学报,2005,26(4):578-580
56巫志华,李亮,丰镇平.三维湿蒸汽自发凝结流动的数值模拟.动力工程,2006,26(6):814-817
57 M. Volmer, H. Flood. Tr?pfchenbildung in D?mpfen. Z. Physik Chem. A. 1934, 170: 273
58 R. Becker, W. D?ring. Kinetische Behandlung der Keimbildung inübersattigten D?mpfen. Ann. Physik. 1935, 24: 710
59 K. Oswatitsch. Kondensationserscheinungen inüberschalldüsen. ZAMM. 1942, 22: 1-14
60 R. Hermann. Der Kondensationssto? inüberschall-Windkan?ldüsen. Luftfahrtforschung. 1942, 19: 201
61 R. M. Head. Investigations of Spontaneous Condensation Phenomena. Ph. D. Dissertation, Calif. Inst. of Technology. 1949
62丰镇平,李亮,李国君.汽轮机湿蒸汽两相凝结流动数值研究的现状与进展.上海汽轮机.2002,(2):1-9
63黄跃.蒸汽透平中自发凝结及流动特性的理论和试验研究.西安交通大学博士学位论文.1987
64李亮.存在自发凝结的湿蒸汽两相非平衡凝结流动的数值研究.西安交通大学博士学位论文.1987
65张冬阳,蒋洪德,刘建军.考虑若干影响的一元蒸汽凝结流数值解.工程热物理学报.2001,22:25-28
66蔡小舒.一种新型的测量汽轮机内湿蒸汽两相流的集成化探针系统.工程热物理学报.2001,22(6):743-746
67蔡小舒.跨音速流自发凝结水滴的测量.流体力学实验与测量.1999,13(3):65-69
68 X. S. Cai. A Novel Method for Measuring the Coarse Water in Wet Steam Flow in Steam Turbine. Journal of Thermal Science. 2001, 10(2): 123-126
69 X. B. Chen, X. S. Cai, X. F. Fan. Experimental Study on Flame Temperature Measurement by Double Line of Atomic Emission Spectroscopy. Spectroscopy and Spectral Analysis. 2009, 12(29): 3177-3180
70 Z. H. Jia, X. L. Fa, J. F. Li. On-Line Measurement of Pneumatic Cconveying of Pulverized Coal in Pipes. 6th International Symposium on Measurement Techniques for Multiphase Flows. Naha, Okinawa, Japan. 2009
71 N. N. Wang,G. Zheng, X. S. Cai. Theoretical and experimental study of the total light scattering technique for particle size analysis. Particle and Particle Systems Characterization. 1994, 4(11): 309-314
72 J. B. Young. The Condensation and Evaporation of Liquid Droplets in a Pure Vapor at Arbitrary Knudsen Number. Int. J. Heat Mass Transfer. 1991, 34(7): 1649-1661
73 J. B. Young. The Condensation and Evaporation of Liquid Droplets at Arbitrary Knudsen.Number in the Presence of an Inert Gas. Int. J. Heat Mass Transfer. 1993, 36: 1649-1661
74 G. Gyarmathy. The Spherical Droplet in Gaseous Carrier Steams: Review andSynthesis. Multiphase Science and Technology. 1982, 1: 99-279
75 G. Gyarmathy. Zur Wachstumsgeschwindigkeit Kleiner Flüssigkeitstropfen in einerübers?ttigten Atmosph?re. Z. für angew. Math. Physik. 1963, 14(3): 280-293
76 C. C. M. Luijten, P. Peeters, M. E. H. Van Dongen. Nucleation at High Pressure. II. Wave Tube Data and Analysis. Journal of Chemical Physics. 1999, 18(111): 8536-8544
77 P. Peeters, J. J. H Gielis, M. E. H. Van Dongen. The Nucleation Behavior of Supercooled Water Vapor in Helium. Journal of Chemical Physics. 2002, 12(117): 5647-5653
78 P. Peeters, G.. Pieterse, M. E. H. van Dongen. Multi-Component Droplet Growth. II. A Theoretical Model. Physics of Fluids. 2004, 7(16): 2575-2586
79 P. Peeters, C. C. M. Muijten, M. E. H. Van Dongen. Transitional Droplet Growth and Diffusion Coefficients. Int J Heat Mass Transfer. 2001, 1(44): 181-193
80 C. C. M. Luijten, M. E. H. van Dongen. Nucleation at High Pressure. I. Theoretical Considerations. Journal of Chemical Physics. 1999, 18(111): 8524-8534
81 G. Lamanna, J. van Poppel, M. E. H. van Dongen. Experimental Determination of Droplet Size and Density Field in Condensing Flows. Experiments in Fluids. 2002, 3(32): 381-395
82 X. S. Luo, G.. Lamanna, A. P. C. Holten,, et al. Effects of Homogeneous Condensation in Compressible Flows: Ludwieg-Tube Experiments and Simulations. Journal of Fluid Mechanics. 2007, 572: 339-366
83 X. S. Luo, B. Prast,Van Dongen, et al. On Phase Transition in Compressible Flows: Modelling and Validation. Journal of Fluid Mechanics. 2006, 548: 403-430
84 K. N. H. Looijmans, M. E. H. van Dongen. Pulse-Expansion Wave Tube for Nucleation Studies at High Pressures. Experiments in Fluids. 1997, 1(23): 54-63
85 K. N. H. Looijmans, C. C. M Luijten, G. C. J. Hofmans, et al. Classical Binary Nucleation Theory Applied to the Real Mixture n-Nonane/Methane at High Pressures. Journal of Chemical Physics. 1995, 11(102): 4531-4537
86 P. G. Hill. Condensation of Water Vapor During Supersonic Expansion in Nozzles. J. Fuild Mech. 1965, 25: 593-620
87童景山,李敬.流体热物理性质的计算[M].北京:清华大学出版社,1982
88 J. B. Young. An Equation of State for Steam for Turbomachinery and other Flow Calculations. Journal of Engineering for Gas Turbines and Power, 1998, 110(1): 1-7
89刘恒伟,刘中良,冯永训,等.过饱和状态下临界液滴半径公式及分析[J].热能动力工程,2005,20(3):254-257,274
90王智.自发凝结湿蒸汽两相流动数值模拟.硕士学位论文.北京:华北电力大学,2003.23—24
91张冬阳,蒋洪德,刘建军.考虑若干影响的一元蒸汽凝结流数值解.工程热物理学报,2001,22(增刊):25—28
92李亮,丰镇平,李国君.一维喷管中存在自发凝结的跨音速湿蒸汽两相流动数值模拟.工程热物理学报,2001,22(6):703—705
93 F. Bakhtar, Z. Ghoneim, J. B. Young. A Study of Nucleation and Wet Steam Flows in Turbines. Proc IME, 190(1976): 545—559
94 F. Bakhta, B. Ghassemi. A Study of Nucleation and Wet Steam Flows in High Pressure Steam Turbines. In :Steam turbines for 1980s, London, Engl: Mech Eng Publ Ltd for Inst of Mech Eng, 1979: 327—336
95童秉纲,孔祥言,邓国华.气体动力学.北京:高等教育出版社,1996.90—102
96陈红梅,李亮,丰镇平等.一维喷管中湿蒸汽非均相凝结流动的研究[J].工程热物理学报,2004,25(3):395-398
97 M. Stastny, M. Sejna. The Effect of Expansion Rate on the Steam Flow with Hetero-Homogeneous Condensation in Nozzles. Proc. IMechE, 2005, 219 (part A: J. Power and Energy): 491-497
98黄跃,蔡颐年.考虑流动摩擦和状态方程Virial修正的Laval喷管湿蒸汽膨胀流动的理论解.工程热物学报.1987,8(4):317-322
99吴凤林,蔡扶时.顶吹转炉氧枪设计,北京:冶金工业部出版社,1982
100蒋汉文,邱信立.热力学原理与应用.上海:同济大学出版社,1990
101施明恒,甘永平,马重芳.沸腾和凝结.北京:高等教育出版社,1995
102王喜魁.风洞收缩段新壁型的研究,沈阳电力高等专科学校,1996.4
103刘卫红.轴对称收缩段设计研究,空气动力学学报,1998.6
104王喜魁.风洞高次曲线收缩段壁型及其性能,空气动力学学报,1997.6
105李记东.超音速/高超音速喷管变比热型面设计与数值模拟,西安西北工业大学硕士论文,2004.3
106周尚波等.劳喷管扩张段优化设计的数值方法研究,宇航学报,2001.9,22(5): 66-71
107钱江波.蒸汽湿度测量方法研究及实验系统设计.华北电力大学硕士学位论文.2004
108 K. Jurski, E. Gehin. Heterogeneous Condensation Process in an Air Water Vapour Expansion through a Nozzle-Experimental Aspect. Int. J. Multiphase Flow, 29(2003): 1137-1152
109冯孝庭.天然气.北京:化学工业出版社,2004:51-52
110 C. C. M. Luijten, R. G. P. Hooy, J. W. F. Janssen, et al. MulticomponentNucleation and Droplet Growth in Natural Gas. 1998, 109(9): 3353-3358
111 P. Peeters, J. Hruby, Marnus, et al. High Pressure Nucleation Expeiment in Binary and Ternary Mixtures. J. Phys. Chem. B., 2001, 105(47): 11763-11771
112 P. Peeters, G. Pieterse, J. Hruby, et al. Multi-Component Droplet Growth. I. Experiments with Supersaturated n-Nonane Vapor and Water Vapor in Methane. Physics of fluids, 2004, 16(7): 2567-2574
113俞茂铮,陈孝隆.存在自发凝结的超音速湿蒸汽双相流.西安交通大学学报,1983,17(1):23-32
114 http://www.pep.com.cn/czhhx/jshzhx/jnshc/jxshj/jshde/200504/t20050413_213328.htm
115 International Association for the Properties of Water and Steam. Guideline on the Use of Fundamental Physical Constants and Basic Constants of Water. http://www.iapws.org/. 2001
116 H. R. Pruppacher, J. D. Klett. Microphysics of Clouds and Precipitation. Dordrecht: Reidel, 1980
117 International Association for the Properties of Water and Steam. Revised Supplementary Release on Saturation Properties of Ordinary Water Substance. http://www.iapws.org/. 1992