气相色谱法分析天然气中苯系物含量

Analysis of the BTEX content in natural gas by gas chromatography

关键词:  天然气  苯系物  气相色谱法  检测限  分离度  重复性  外标法

Key words:  natural gas  BTEX  gas chromatography  detection limit  repeatability  resolution  external standard method

摘要:

苯系物(BTEX)通常包括苯、甲苯、乙苯和二甲苯等芳香族化合物,一般天然气中含有微量的苯系物。在天然气生产和加工环节,检测苯系物组分含量对预测天然气烃露点/烃含量具有重要意义。通过实验,建立了采用气相色法分析苯系物含量的方法,各苯系物定性重复性RSD7(定性)不超过0.01%；苯和甲苯定量重复性RSD7(定量)不超过2.5%,乙苯和二甲苯定量重复性RSD7(定量)为7%～11%；各组分最低检测限可达约2×10-10 g/s；对二甲苯和间二甲苯的分离度达到2.2。分析实际天然气样品,验证了该方法的可行性和适用性。获得的结论对准确检测天然气中苯系物含量提供了技术参考,为使用天然气组成数据准确预测烃露点/烃含量提供了可靠的完整数据,计算获得的烃露点/烃含量对天然气处理厂脱烃装置工艺设计和输气管道的安全运行提供数据支持。

Abstract:

Benzene series (BTEX) usually include aromatic compounds such as benzene, toluene, ethylbenzene and xylene. In general, natural gas contains trace benzene series. In natural gas production and processing, it is important to detect the content of benzene series components and predict natural gas dew point/hydrocarbon content. Through the experiment, the method of analyzing the content of benzene series by gas chromatography is established, the qualitative repeatability (RSD₇) of each benzene series is not more than 0.01%, the quantitative repeatability of benzene and toluene (RSD₇) is not more than 2.5%, the quantitative repeatability of ethylbenzene and xylene (RSD₇) is between 7% and 11%, and the minimum detection limit of each component can reach about 2×10-10 g/s, and the separation degree of para-xylene and m-xylene is 2.2. The feasibility and applicability of the method are verified by analyzing the actual natural gas sample, and the obtained conclusion can provide technical reference for accurately detecting the benzene content in natural gas, which can provide basic data for accurately predicting hydrocarbon dew point by using natural gas composition data, and has practical significance for the process design of the dealkylation unit of the natural gas treatment plant and the safe operation of the gas pipeline.