某石油炼制企业VOCs排放源强反演研究

选取我国北方某石油炼制企业为研究对象,针对其挥发性有机物(VOCs)排放,于春季3月开展了厂界周边大气VOCs环境浓度监测,并利用ISCST-3空气质量模型反推出该企业VOCs排放源强.监测结果表明,厂外上风向背景点与下风向受体点TVOCs浓度平均值分别为28.6×10-9和88.3×10-9,且2个区域VOCs还存在化学组分特征差异,背景点以乙烷、丙烷、乙烯为主,而受体点化学组分中丙烯、异丁烷、丁烷、异戊烷、戊烷的体积浓度百分比显著上升,说明该炼油厂VOCs排放体量大,对局地环境影响显著.扣除背景点VOCs,获得了该炼油厂VOCs排放化学成分谱,其主要成分体积浓度百分比:乙烷(23.4%)、丙烷(11.8%)、丁烷(10.4%)、异丁烷(9.0%)、戊烷(5.3%)、异戊烷(6.4%)、丙烯(11.5%),成分谱特征与国内相关文献相似.ISCST-3模型反演结果显示,该炼油厂TVOCs年排放量平均值为(2201.6±1011.9) t/a,折合排放因子约0.73g VOCs/kg原油.该计算结果偏低,原因可能在于:其一,测试季节为春季,较低的环境温度致使了炼油厂挥发散逸环节的排放低于全年平均水平;其二,ISCST-3模型为扩散模型,未考虑VOCs化合物在局地范围的化学衰减.

Inversion research in VOCs source emission of a petroleum refinery

This study selected a petroleum refinery located in Northern China to calculate its VOCs emission amount, by combing its ambient atmospheric VOCs concentration monitored in March and ISCST-3air quality model. The monitoring results showed the average TVOCs concentration in receptors and in background were 28.6×10-9 and 88.3×10-9 respectively. In addition, there were significant differences between receptors and background in the VOCs chemical composition. Ethane, propane and ethylene were the dominant component in background, but the volume percentage of propylene, isobutane, butane, isopentane, pentane increased significantly in receptor. It was indicated the VOCs emitted from petroleum refinery had a large impact on local environment. The chemical profile of refinery VOCs emissions was obtained by subtracting VOCs in background from those in receptors, and the main compounds included ethane (23.4%), propane (11.8%), butane (10.4%), isobutene (9.0%), pentane (5.3%), isopentane (6.4%), propylene (11.5%), which was similar to the literature results in China. The inversion results of ISCST-3model showed the annual VOCs emission was 2201.6±1011.9t/a, with the VOCs emission factor of 0.73g VOCs/kg crude oil. This result was smaller compared to the researches, possibly due to two reasons: 1, lower ambient temperature in spring resulted in the less evaporation emissions ; 2, the local chemical decay of VOCs was not included in ISCST-3model.