节流降温对天然气大流量计量检定准确性的影响与对策
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摘要
天然气大流量计量站需要对进站介质进行流量、压力和温度的综合性调节以满足检定的要求,由此也带来了因节流降温和气源温度不稳定致使标准表示值失真的问题。为此,对典型天然气大流量计量站检定流程、气源条件等进行分析,研究温度变化对检定介质的物性影响及对检定管路热变形的影响,并计算温降所引起的检定误差值;同时,对气源进行复热处理以消除检定介质节流温降所带来的测量误差影响。研究结果表明:①温度变化影响天然气密度变化,由此介质每产生1℃的温降波动则会对检定结果带来0.045%的误差;②温度变化造成检定管道的热变形,介质温度每降低4℃则产生0.01%的相对误差;③有针对性地采用了一种电伴热管路和加热炉复合应用的天然气复热工艺,可有效减小计量仪表的测量误差。结论认为,检定介质温降变化对计量检定结果的准确评价造成的影响不可忽视,应进一步探索量传水平变化规律,采取准确控制温度变化的天然气复热工艺,以此来提高天然气贸易计量过程的稳定性和准确度。
In order to meet the verification requirements, it is necessary to carry out comprehensive adjustment on the flow rate, pressure and temperature of incoming medium at large-flow natural gas metering stations. As a result, however, the standard representation value is distorted due to the temperature drop after throttling and the unstable temperature of gas source. In this paper, the verification process and gas source conditions of typical large-flow natural gas metering stations were analyzed. Then, the influences of temperature change on the physical properties of the verification medium and the thermal deformation of the verification pipeline were studied, and the verification error caused by the temperature drop was calculated. Finally, the gas source was reheated so as to eliminate the influence of the measurement error caused by temperature drop after throttling of the verification medium. And the following research results were obtained. First, temperature change can affect the change of natural gas density, and the temperature drop of medium by 1 ℃ will bring about 0.045% error to the verification result. Second, temperature change can affect the thermal deformation of the verification pipeline,and the temperature drop of medium by 4 ℃ will result in a relative error of 0.01%. Third, the measurement error of the metering instruments can be effectively reduced by adopting specifically a natural gas reheating process which combines electric heat tracing pipeline and heating furnace together. In conclusion, the influence of the temperature drop of verification medium on the accurate evaluation of the measurement results shall not be ignored. It is necessary to further explore the law of the horizontal changes in volume and take the natural gas reheating process that can accurately control temperature change, so as to improve the stability and accuracy of the measurement process of natural gas trade.
In order to meet the verification requirements, it is necessary to carry out comprehensive adjustment on the flow rate, pressure and temperature of incoming medium at large-flow natural gas metering stations. As a result, however, the standard representation value is distorted due to the temperature drop after throttling and the unstable temperature of gas source. In this paper, the verification process and gas source conditions of typical large-flow natural gas metering stations were analyzed. Then, the influences of temperature change on the physical properties of the verification medium and the thermal deformation of the verification pipeline were studied, and the verification error caused by the temperature drop was calculated. Finally, the gas source was reheated so as to eliminate the influence of the measurement error caused by temperature drop after throttling of the verification medium. And the following research results were obtained. First, temperature change can affect the change of natural gas density, and the temperature drop of medium by 1 ℃ will bring about 0.045% error to the verification result. Second, temperature change can affect the thermal deformation of the verification pipeline,and the temperature drop of medium by 4 ℃ will result in a relative error of 0.01%. Third, the measurement error of the metering instruments can be effectively reduced by adopting specifically a natural gas reheating process which combines electric heat tracing pipeline and heating furnace together. In conclusion, the influence of the temperature drop of verification medium on the accurate evaluation of the measurement results shall not be ignored. It is necessary to further explore the law of the horizontal changes in volume and take the natural gas reheating process that can accurately control temperature change, so as to improve the stability and accuracy of the measurement process of natural gas trade.
引文
[1]蔡黎,潘春锋,李彦,罗勤,唐蒙.多气源环境下进入长输管道气质要求探讨[J].石油与天然气化工,2014,43(3):313-317.Cai Li,Pan Chunfeng,Li Yan,Luo Qin&Tang Meng.Discussion on quality requirements of natural gas entering long distance pipeline in multiple gas sources environment[J].Chemical Engineering of Oil&Gas,2014,43(3):313-317.
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[7]高军.大流量天然气的计量和仪表检定[J].油气田地面工程,2001,20(6):51-52.Gao Jun.Metering of natural gas with high pressure and large diameter and instrument calibration[J].Oil-Gasfield Surface Engineering,2001,20(6):51-52.
[8]李琳.气源温度及管容对流量计检定精度的影响研究[D].成都:西南石油大学,2013.Li Lin.The study of impact of natural gas temperature and pipe volume in flowmeter verification[D].Chengdu:Southwest Petroleum University,2013.
[9]肖迪,徐军.检定介质温度、压力对流量计在线检定的影响[J].天然气工业,2007,27(5):113-114.Xiao Di&Xu Jun.Influences of medium temperature and pressure on online flowrate measurement of flowmeters[J].Natural Gas Industry,2007,27(5):113-114.
[10]郑传波,许潘文,黄冠文,陈行川.温度偏差对天然气流量计检定结果的影响[J].计量学报,2016,37(增刊1):190-193.Zheng Chuanbo,Xu Panwen,Huang Guanwen&Chen Hangchuan.Effect of temperature deviation on natural gas flow-meter verification results[J].Acta Metrologica Sinica,2016,37(S1):190-193.
[11]聂群.天然气配气站计量系统的改造[J].油气储运,2017,36(10):1217-1222.Nie Qun.Reconstruction of metering system at natural gas distribution substation[J].Oil&Gas Storage and Transportation,2017,36(10):1217-1222.
[12]王吉开.国家石油天然气大流量计量站武汉分站标准涡轮流量计防护措施[J].化工管理,2017(32):244-245.Wang Jikai.National Oil and Natural Gas Large Flow Metering Station Wuhan Substation standard turbine flowmeter protection measures[J].Chemical Enterprise Management,2017(32):244-245.
[13]王海向.天然气大流量计量检定系统的设计[J].石油化工自动化,2017,53(3):60-64.Wang Haixiang.Design of metrological verification system for natural gas mass flow[J].Automation in Petro-Chemical Industry,2017,53(3):60-64.
[14]朱瑞苗,闫文灿,高志国.天然气实流原级检定装置加热系统技术研究[J].石油化工自动化,2015,51(5):70-73.Zhu Ruimiao,Yan Wencan&Gao Zhiguo.Technique study of heating system for actual natural gas flow calibration primary standard device[J].Automation in Petro-Chemical Industry,2015,51(5):70-73.
[15]国明昌,丁建林,邱惠.高压天然气流量计现场在线实流检定[J].计量学报,2008,29(5):411-415.Guo Mingchang,Ding Jianlin&Qiu Hui.In-situ calibration of high pressure natural gas flowmeters[J].Acta Metrologica Sinica,2008,29(5):411-415.
[16]中国国家标准化管理委员会.天然气标准参比条件:GB/T19205-2008[S].北京:中国标准出版社,2008.Standardization Administration of the PRC.Natural gas standard reference conditions:GB/T 19205-2008[S].Beijing:Standards Press of China,2008.
[17]李丹华,姜东琪.AGA8-92DC计算方法天然气压缩因子计算[J].煤气与热力,2011,31(3):35-38.Li Danhua&Jiang Dongqi.Calculation of compression factor of natural gas by AGA8-92DC method[J].Gas&Heat,2011,31(3):35-38.
[18]林武,李红英,曾翠婷,宾杰,魏冬冬.一种低碳微合金管线钢的热变形行为[J].中南大学学报(自然科学版),2010,41(3):940-947.Lin Wu,Li Hongying,Zeng Cuiting,Bin Jie&Wei Dongdong.Hot deformation behavior for a kind of low carbon micro-alloy pipeline steel[J].Journal of Central South University(Science and Technology),2010,41(3):940-947.
[2]许晓英,赵庆凯,陈丰波,孔冰.多相流量计在国内市场的应用及发展趋势[J].石油与天然气化工,2017,46(2):99-104.Xu Xiaoying,Zhao Qingkai,Chen Fengbo&Kong Bing.Application and development trend of multiphase flow meter in the domestic market[J].Chemical Engineering of Oil&Gas,2017,46(2):99-104.
[3]陈赓良.天然气能量计量的技术进展[J].石油与天然气化工,2015,44(1):1-7.Chen Gengliang.Progress of natural gas energy measurement technology[J].Chemical Engineering of Oil&Gas,2015,44(1):1-7.
[4]李琳.天然气大流量测量不确定度分析研究[J].广东化工,2015,42(4):115-116.Li Lin.Analysis of uncertainty in natural gas flow measurement[J].Guangdong Chemical Industry,2015,42(4):115-116.
[5]黄和,徐刚,余汉成,陈凤.国内外天然气流量计量检测技术现状及进展[J].天然气与石油,2009,27(2):42-47.Huang He,Xu Gang,Yu Hancheng&Chen Feng.Present situation and research progress of testing technology in natural gas flow measurement at home and abroad[J].Natural Gas and Oil,2009,27(2):42-47.
[6]秦云松,张吉军,林媛媛.天然气流量计量标准装置的工艺流程优化[J].天然气工业,2017,37(8):102-107.Qin Yunsong,Zhang Jijun&Lin Yuanyuan.Process optimization of a natural gas flow measurement standard device[J].Natural Gas Industry,2017,37(8):102-107.
[7]高军.大流量天然气的计量和仪表检定[J].油气田地面工程,2001,20(6):51-52.Gao Jun.Metering of natural gas with high pressure and large diameter and instrument calibration[J].Oil-Gasfield Surface Engineering,2001,20(6):51-52.
[8]李琳.气源温度及管容对流量计检定精度的影响研究[D].成都:西南石油大学,2013.Li Lin.The study of impact of natural gas temperature and pipe volume in flowmeter verification[D].Chengdu:Southwest Petroleum University,2013.
[9]肖迪,徐军.检定介质温度、压力对流量计在线检定的影响[J].天然气工业,2007,27(5):113-114.Xiao Di&Xu Jun.Influences of medium temperature and pressure on online flowrate measurement of flowmeters[J].Natural Gas Industry,2007,27(5):113-114.
[10]郑传波,许潘文,黄冠文,陈行川.温度偏差对天然气流量计检定结果的影响[J].计量学报,2016,37(增刊1):190-193.Zheng Chuanbo,Xu Panwen,Huang Guanwen&Chen Hangchuan.Effect of temperature deviation on natural gas flow-meter verification results[J].Acta Metrologica Sinica,2016,37(S1):190-193.
[11]聂群.天然气配气站计量系统的改造[J].油气储运,2017,36(10):1217-1222.Nie Qun.Reconstruction of metering system at natural gas distribution substation[J].Oil&Gas Storage and Transportation,2017,36(10):1217-1222.
[12]王吉开.国家石油天然气大流量计量站武汉分站标准涡轮流量计防护措施[J].化工管理,2017(32):244-245.Wang Jikai.National Oil and Natural Gas Large Flow Metering Station Wuhan Substation standard turbine flowmeter protection measures[J].Chemical Enterprise Management,2017(32):244-245.
[13]王海向.天然气大流量计量检定系统的设计[J].石油化工自动化,2017,53(3):60-64.Wang Haixiang.Design of metrological verification system for natural gas mass flow[J].Automation in Petro-Chemical Industry,2017,53(3):60-64.
[14]朱瑞苗,闫文灿,高志国.天然气实流原级检定装置加热系统技术研究[J].石油化工自动化,2015,51(5):70-73.Zhu Ruimiao,Yan Wencan&Gao Zhiguo.Technique study of heating system for actual natural gas flow calibration primary standard device[J].Automation in Petro-Chemical Industry,2015,51(5):70-73.
[15]国明昌,丁建林,邱惠.高压天然气流量计现场在线实流检定[J].计量学报,2008,29(5):411-415.Guo Mingchang,Ding Jianlin&Qiu Hui.In-situ calibration of high pressure natural gas flowmeters[J].Acta Metrologica Sinica,2008,29(5):411-415.
[16]中国国家标准化管理委员会.天然气标准参比条件:GB/T19205-2008[S].北京:中国标准出版社,2008.Standardization Administration of the PRC.Natural gas standard reference conditions:GB/T 19205-2008[S].Beijing:Standards Press of China,2008.
[17]李丹华,姜东琪.AGA8-92DC计算方法天然气压缩因子计算[J].煤气与热力,2011,31(3):35-38.Li Danhua&Jiang Dongqi.Calculation of compression factor of natural gas by AGA8-92DC method[J].Gas&Heat,2011,31(3):35-38.
[18]林武,李红英,曾翠婷,宾杰,魏冬冬.一种低碳微合金管线钢的热变形行为[J].中南大学学报(自然科学版),2010,41(3):940-947.Lin Wu,Li Hongying,Zeng Cuiting,Bin Jie&Wei Dongdong.Hot deformation behavior for a kind of low carbon micro-alloy pipeline steel[J].Journal of Central South University(Science and Technology),2010,41(3):940-947.