多气源混输管道在线气相色谱仪安装位置的确定方法
|
摘要
采用在线气相色谱仪实时监测管道中天然气组分的变化是目前大型输气场站保证天然气计量准确性的关键工艺,而在线气相色谱仪抽取样品的代表性则是保证分析检测结果准确可靠的关键因素,对于多气源汇合的输气场站,不同气源天然气的混合程度直接关系到在线气相色谱仪所取样品的代表性。为此,以中石化川气东送工程的普光首站为例,按照该站的工况条件,采用FLUENT软件对多气源天然气的混合规律进行了仿真模拟,探讨了多气源天然气混合距离与温度、压力、流速等因素的关系,以及多气源天然气混合均匀的最近位置。试验结果表明:(1)含两种不同摩尔分数值组分的天然气在汇管不同位置处混合的均匀程度不同——距汇管50 m处天然气各组分混合不均匀,具明显分层现象,距汇管150 m处天然气各组分的混合开始呈现均匀状态,但仍存在分层现象,距汇管280 m处天然气各组分混合完全呈现出均匀状态,其CH_4摩尔分数为98.30%,CO_2摩尔分数为0.95%;(2)在普光首站距混合点280 m以远处的位置安装在线气相色谱仪取样较为合适;(3)对于气源体积流量或气源的体积流量差别较大、压力较高或温度较低的工况条件,在线气相色谱仪的取样点可适当靠近混合点。
To perform real-time monitoring on the compositional change of natural gas in the pipelines by using an on-line gas chromatograph is the key process to ensure the accuracy of natural gas metering in large gas stations. And the representativeness of samples taken by the on-line gas chromatograph is crucial to guarantee the accuracy and reliability of the test analysis results. At the gas transportation stations with multiple gas sources, the representativeness of samples taken by the on-line gas chromatograph is directly dependent on the mixing degree of natural gas from different sources. In this paper, the Puguang Initial Station of the pipelines in the Sinopec's Sichuan-to-East China Gas Project was taken as an example. Based on its behaviors, the FLUENT software was used to simulate the mixing rules of multiple-source natural gas. Then, the relationships between the mixing distance of multiple-source natural gas and the temperature, pressure and flow rate were discussed, and the closest uniform mixing location of multiple-source natural gas was confirmed. It is indicated that natural gas composed of two compositions with different mole fractions is different in term of its mixing uniformity degree at different distances from the manifold; the compositions of the natural gas aren't mixed uniformly at the location 50 m away from the manifold, and the phenomenon of stratification is obvious; at the location 150 m away from the manifold, the uniform mixing of natural gas compositions emerges initially, but the phenomenon of stratification still exists; located about 280 m away from the manifold, the compositions of natural gas are completely in a homogeneous state with CH_4 mole fraction of 98.30% and CO_2 mole fraction of 0.95%. Therefore, it is suggested that the on-line gas chromatograph should be placed at least 280 m away from the mixing point of the Puguang Station. In the working conditions of higher volume flow rates of the mixed gas or greater variations of volume flow rates between different gases, or gas under higher pressures or lower temperatures, the sampling point of the on-line gas chromatograph shall all be close to the mixing point properly.
To perform real-time monitoring on the compositional change of natural gas in the pipelines by using an on-line gas chromatograph is the key process to ensure the accuracy of natural gas metering in large gas stations. And the representativeness of samples taken by the on-line gas chromatograph is crucial to guarantee the accuracy and reliability of the test analysis results. At the gas transportation stations with multiple gas sources, the representativeness of samples taken by the on-line gas chromatograph is directly dependent on the mixing degree of natural gas from different sources. In this paper, the Puguang Initial Station of the pipelines in the Sinopec's Sichuan-to-East China Gas Project was taken as an example. Based on its behaviors, the FLUENT software was used to simulate the mixing rules of multiple-source natural gas. Then, the relationships between the mixing distance of multiple-source natural gas and the temperature, pressure and flow rate were discussed, and the closest uniform mixing location of multiple-source natural gas was confirmed. It is indicated that natural gas composed of two compositions with different mole fractions is different in term of its mixing uniformity degree at different distances from the manifold; the compositions of the natural gas aren't mixed uniformly at the location 50 m away from the manifold, and the phenomenon of stratification is obvious; at the location 150 m away from the manifold, the uniform mixing of natural gas compositions emerges initially, but the phenomenon of stratification still exists; located about 280 m away from the manifold, the compositions of natural gas are completely in a homogeneous state with CH_4 mole fraction of 98.30% and CO_2 mole fraction of 0.95%. Therefore, it is suggested that the on-line gas chromatograph should be placed at least 280 m away from the mixing point of the Puguang Station. In the working conditions of higher volume flow rates of the mixed gas or greater variations of volume flow rates between different gases, or gas under higher pressures or lower temperatures, the sampling point of the on-line gas chromatograph shall all be close to the mixing point properly.
引文
[1]彭世尼,蒋星池.天然气多气源混输系统的安全性分析[J].煤气与热力,2014,34(12):1-3.Peng Shini&Jiang Xingchi.Security analysis of natural gas mixed transmission system with multiple gas sources[J].Gas&Heat,2014,34(12):1-3.
[2]刘武,纪国文,季寿宏,何春龙.多气源混输条件下天然气互换性问题分析——以浙江省天然气管网系统为例[J].石油与天然气化工,2014,43(4):401-404.Liu Wu,Ji Guowen,Ji Shouhong&He Chunlong.Analysis of natural gas interchangeability under the condition of multiple gas mixed transportation:A case study in natural gas pipe network system of Zhejiang province[J].Chemical Engineering of Oil&Gas,2014,43(4):401-404.
[3]王冠培,苏清博,郭开华,李宁,皇甫立霞.多气源混输管网的供气方案[J].油气储运,2013,32(10):1063-1067.Wang Guanpei,Su Qingbo,Guo Kaihua,Li Ning&Huangfu Lixia.Gas supply program for pipeline network with multiple gas sources[J].Oil&Gas Storage and Transportation,2013,32(10):1063-1067.
[4]李鸿鹏,刘轲.多气源混输对输配管网及终端用户的影响分析[C]//第二届中国液化天然气储运技术交流会论文集,2016-1-12,广州,中国.广州:中国石油学会,2016.Li Hongpeng&Liu Ke.Analysis on the influence of multiple sources mixture on transmission and distribution network and end user[C]//Liquefied Natural Gas Storage and Transportation Technology Exchange of China,12 January 2016,Guangzhou.Guangzhou:Chinese Petroleum Society,2016.
[5]吴华丽,孙石磊.多气源混输管网下的供气方案[J].管道技术与设备,2011(5):54-56.Wu Huali&Sun Shilei.Gas supply projects for gas grid with multiple gases as source[J].Pipeline Technique and Equipment,2011(5):54-56.
[6]梁永宽.多气源混合输送的市场特点与定价原则[C]//第3届中国城市燃气论坛论文集,2010-12-1,深圳,中国.深圳:中国土木工程学会,2010.Liang Yongkuan.Market characteristics and pricing principle of mixed transportation of multiple sources[C]//China City Gas Forum,1 December 2010,Shenzhen.Shenzhen:Chinese Society of Civil Engineering,2010.
[7]王云龙.多气源天然气混合调配问题的探索与研究[J].化工管理,2015(28):161.Wang Yunlong.Exploration and research on distribution of natural gas with multiple sources[J].Chemical Enterprise Management,2015(28):161.
[8]张振武,张雷,石岩.多气源天然气混合调配问题的探索与研究[J].内蒙古石油化工,2013,39(16):7-9.Zhang Zhenwu,Zhang Lei&Shi Yan.Exploration and research on distribution of natural gas with multiple sources[J].Inner Mongolia Petrochemical Industry,2013,39(16):7-9.
[9]马良涛,王香.气相色谱法分析天然气成分[J].光谱实验室,2000,17(5):605-609.Ma Liangtao&Wang Xiang.Determination of composition in natural gas by gas chromatography[J].Chinese Journal of Spectroscopy Laboratory,2000,17(5):605-609.
[10]韩占忠,王敬,兰小平.Fluent——流体工程仿真计算实例与应用[M].北京:北京理工大学出版社,2004.Han Zhanzhong,Wang Jing&Lan Xiaoping.Fluent—example and application of fluid engineering simulation[M].Beijing:Beijing Institute of Technology Press,2004.
[11]段永红,徐庆磊,孙丽,刘颖,李先明.基于Fluent的三通三维数值模拟[J].内蒙古石油化工,2008(5):51-53.Duan Yonghong,Xu Qinglei,Sun Li,Liu Ying&Li Xianming.The three-dimensional numerical simulation of the tee coupling tube based on the Fluent[J].Inner Mongolia Petrochemical Industry,2008(5):51-53.
[12]朱文君,程佳,吴焕芬,黄震威.浙江省多气源混合天然气管网稳态仿真研究[J].中国计量学院学报,2013,24(1):92-96.Zhu Wenjun,Cheng Jia,Wu Huanfen&Huang Zhenwei.Steady state simulation of multi-gas sources mixed natural gas pipeline network in Zhejiang Province[J]Journal of China University of Metrology,2013,24(1):92-96.
[13]王冠培,郭开华,潘国君.基于CFD的天然气管道混气扩散规律研究[J].热科学与技术,2015,14(6):484-491.Wang Guanpei,Guo Kaihua&Pan Guojun.Research on natural gas pipeline mixing-flow properties based on computational fluid dynamics[J].Journal of Thermal Science and Technology,2015,14(6):484-491.
[14]魏显达,王为民,徐建普.基于Fluent的三通管数值模拟及分析[J].当代化工,2011,40(2):165-167.Wei Xianda,Wang Weimin&Xu Jianpu.Numerical simulation and analysis of fluid in three-way connection pipe based on fluent software[J].Contemporary Chemical Industry,2011,40(2):165-167.
[15]周萍,周乃君,蒋爱华,陈红荣.传递过程原理及其数值仿真[M].长沙:中南大学出版社,2006.Zhou Ping,Zhou Naijun,Jiang Aihua&Chen Hongrong.Principle and numerical simulation of transport process[M].Changsha:Central South University Press,2006.
[16]肖国民,李浩扬,肖洋.通用化工模拟软件在《化工传递过程原理》教学中的应用[J].化工时刊,2012,26(10):53-59.Xiao Guomin,Li Haoyang&Xiao Yang.Application of general chemical simulation software in the teaching of Principles of Chemical Engineering Transport Process[J].Chemical Industry Times,2012,26(10):53-59.
[2]刘武,纪国文,季寿宏,何春龙.多气源混输条件下天然气互换性问题分析——以浙江省天然气管网系统为例[J].石油与天然气化工,2014,43(4):401-404.Liu Wu,Ji Guowen,Ji Shouhong&He Chunlong.Analysis of natural gas interchangeability under the condition of multiple gas mixed transportation:A case study in natural gas pipe network system of Zhejiang province[J].Chemical Engineering of Oil&Gas,2014,43(4):401-404.
[3]王冠培,苏清博,郭开华,李宁,皇甫立霞.多气源混输管网的供气方案[J].油气储运,2013,32(10):1063-1067.Wang Guanpei,Su Qingbo,Guo Kaihua,Li Ning&Huangfu Lixia.Gas supply program for pipeline network with multiple gas sources[J].Oil&Gas Storage and Transportation,2013,32(10):1063-1067.
[4]李鸿鹏,刘轲.多气源混输对输配管网及终端用户的影响分析[C]//第二届中国液化天然气储运技术交流会论文集,2016-1-12,广州,中国.广州:中国石油学会,2016.Li Hongpeng&Liu Ke.Analysis on the influence of multiple sources mixture on transmission and distribution network and end user[C]//Liquefied Natural Gas Storage and Transportation Technology Exchange of China,12 January 2016,Guangzhou.Guangzhou:Chinese Petroleum Society,2016.
[5]吴华丽,孙石磊.多气源混输管网下的供气方案[J].管道技术与设备,2011(5):54-56.Wu Huali&Sun Shilei.Gas supply projects for gas grid with multiple gases as source[J].Pipeline Technique and Equipment,2011(5):54-56.
[6]梁永宽.多气源混合输送的市场特点与定价原则[C]//第3届中国城市燃气论坛论文集,2010-12-1,深圳,中国.深圳:中国土木工程学会,2010.Liang Yongkuan.Market characteristics and pricing principle of mixed transportation of multiple sources[C]//China City Gas Forum,1 December 2010,Shenzhen.Shenzhen:Chinese Society of Civil Engineering,2010.
[7]王云龙.多气源天然气混合调配问题的探索与研究[J].化工管理,2015(28):161.Wang Yunlong.Exploration and research on distribution of natural gas with multiple sources[J].Chemical Enterprise Management,2015(28):161.
[8]张振武,张雷,石岩.多气源天然气混合调配问题的探索与研究[J].内蒙古石油化工,2013,39(16):7-9.Zhang Zhenwu,Zhang Lei&Shi Yan.Exploration and research on distribution of natural gas with multiple sources[J].Inner Mongolia Petrochemical Industry,2013,39(16):7-9.
[9]马良涛,王香.气相色谱法分析天然气成分[J].光谱实验室,2000,17(5):605-609.Ma Liangtao&Wang Xiang.Determination of composition in natural gas by gas chromatography[J].Chinese Journal of Spectroscopy Laboratory,2000,17(5):605-609.
[10]韩占忠,王敬,兰小平.Fluent——流体工程仿真计算实例与应用[M].北京:北京理工大学出版社,2004.Han Zhanzhong,Wang Jing&Lan Xiaoping.Fluent—example and application of fluid engineering simulation[M].Beijing:Beijing Institute of Technology Press,2004.
[11]段永红,徐庆磊,孙丽,刘颖,李先明.基于Fluent的三通三维数值模拟[J].内蒙古石油化工,2008(5):51-53.Duan Yonghong,Xu Qinglei,Sun Li,Liu Ying&Li Xianming.The three-dimensional numerical simulation of the tee coupling tube based on the Fluent[J].Inner Mongolia Petrochemical Industry,2008(5):51-53.
[12]朱文君,程佳,吴焕芬,黄震威.浙江省多气源混合天然气管网稳态仿真研究[J].中国计量学院学报,2013,24(1):92-96.Zhu Wenjun,Cheng Jia,Wu Huanfen&Huang Zhenwei.Steady state simulation of multi-gas sources mixed natural gas pipeline network in Zhejiang Province[J]Journal of China University of Metrology,2013,24(1):92-96.
[13]王冠培,郭开华,潘国君.基于CFD的天然气管道混气扩散规律研究[J].热科学与技术,2015,14(6):484-491.Wang Guanpei,Guo Kaihua&Pan Guojun.Research on natural gas pipeline mixing-flow properties based on computational fluid dynamics[J].Journal of Thermal Science and Technology,2015,14(6):484-491.
[14]魏显达,王为民,徐建普.基于Fluent的三通管数值模拟及分析[J].当代化工,2011,40(2):165-167.Wei Xianda,Wang Weimin&Xu Jianpu.Numerical simulation and analysis of fluid in three-way connection pipe based on fluent software[J].Contemporary Chemical Industry,2011,40(2):165-167.
[15]周萍,周乃君,蒋爱华,陈红荣.传递过程原理及其数值仿真[M].长沙:中南大学出版社,2006.Zhou Ping,Zhou Naijun,Jiang Aihua&Chen Hongrong.Principle and numerical simulation of transport process[M].Changsha:Central South University Press,2006.
[16]肖国民,李浩扬,肖洋.通用化工模拟软件在《化工传递过程原理》教学中的应用[J].化工时刊,2012,26(10):53-59.Xiao Guomin,Li Haoyang&Xiao Yang.Application of general chemical simulation software in the teaching of Principles of Chemical Engineering Transport Process[J].Chemical Industry Times,2012,26(10):53-59.