液化天然气(Liquefied Natural Gas，LNG)接收站内有大量的法兰、阀门、开口管、连接件等设备，设备内输送的LNG介质与外界环境温差大，其密封点处容易发生老化变形而引发甲烷泄漏，从而造成环境污染。目前，国内外缺少对LNG接收站设备甲烷逸散浓度与甲烷逸散速率检测及排放量的核算方法，难以准确地对LNG接收站甲烷逸散排放量进行核算。研究对LNG接收站高压泵区、管廊区、罐区等12个检测区域，3 243个设备的甲烷逸散浓度进行检测，明确了4类设备及12个区域的泄漏概率，量化了甲烷排放速率，构建了甲烷排放因子，修正了将甲烷逸散浓度换算为甲烷逸散速率的相关方程。结果显示，LNG接收站检测到252个泄漏点，占设备数总量的8％，主要集中在蒸发气(Boil Off Gas，BOG)压缩区、卸船区、高压泵区和罐区。LNG接收站场总排放量为5 756。21 kg/a，其中1。17％的设备贡献了约89％的排放量。相较于天然气输气站和压气站，LNG接收站的泄漏概率更大。研究成果为量化LNG接收站设备密封点排放总量及甲烷减排措施的制定提供了参考。
Characteristics and quantification of greenhouse gas methane emission in LNG terminals
Equipment such as flanges,valves,open pipes,and connectors within Liquefied Natural Gas(LNG)terminals are susceptible to methane leakage due to aging and deformation,which poses risks of environmental pollution.Currently,there is a lack of standardized accounting methods for equipment emissions at LNG terminals,both domestically and internationally.This study utilizes a Hydrogen Flame Ionization Detector(FID)and a High-Flow Sampler(HI-FLOW)to measure methane emission concentrations and rates across 12 monitoring areas,including the high-pressure pump area,pipe rack area,and tank area,covering a total of 3 243 equipment items at an LNG terminal.The probability of methane leaks for four types of equipment across the 12 monitoring areas was assessed.Utilizing the detection data,relevant equations for converting methane emission concentrations to emission rates were revised,allowing for the quantification of methane emission rates from equipment in these areas.Additionally,methane emission factors were established,enabling future studies to estimate the methane emission rates of the four types of equipment at other LNG terminals by simply inputting the number of equipment items.The results indicate that approximately 92％of the equipment at the LNG terminal has a methane emission molar ratio below 100 µmol/mol,suggesting that most equipment is functioning normally.Approximately 1％of the equipment has a methane emission molar ratio exceeding 10 000 µmol/mol,indicating severe leakage.A total of 252 leak points were identified at the LNG terminal,representing about 8％of the total equipment.These leaks are primarily concentrated in the Boil Off Gas(BOG)compression area,unloading area,high-pressure pump area,and tank area.The total emissions from the LNG terminal site amount to 5 756.21 kg/a,with 1.17％of the equipment responsible for approximately 89％of the methane emissions.This indicates that methane emissions at the LNG terminal are largely driven by a small number of significant leak points.The average emission factors for flanges,open pipes,connectors,and valves are 3.78,2.76,0.53,and 1.08,respectively.These findings serve as a reference for quantifying total emissions from sealing points of equipment at LNG terminals and for developing effective methane reduction strategies.
environmental engineeringliquefied natural gas terminalmethane leakagefugitive concentrationemission ratesconversion technique
万方数据
维普
