气体质量流量控制器在汽车VOC检测领域的应用

汽车挥发性有机物组分(VOC)检测过程中,充气和采气体积的计量对检测结果的影响尤为突出.通过气体质量流量控制器与目前VOC检测中常用的恒流气体采样装置的比较,表明在同样满足VOC检测标准要求的情况下,气体质量流量控制器在排除环境干扰等方面体现出更好的稳定性,更有利于汽车VOC检测准确度的提高.     

炼化装置挥发性有机物检测方法介绍

结合石油化工行业生产的实际,介绍一种炼化装置挥发性有机物检测方法,并依据EPA的计算方法对装置的挥发性有机物的泄漏量进行了估算.     

Use of thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) on identification of odorant emission focus by volatile organic compounds characterisation

Volatile organic compounds (VOCs) from several different municipal solid wastes’ treatment plants in Mallorca (Spain) have been analysed by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). Ambient (immission) air was collected during February and March 2011 by active sampling onto sorbents Tenax™ TA and Carboxen™ 1000. The study presents the chemical characterisation of 93 volatile organic compounds (VOCs) from an overall set of 84 immission air samples. 70 VOCs were positively identified.The linear fit for all 93 external standard calibration, from 10 mg L⁻¹ to 150 mg L⁻¹ (n = 4), was within the range 0.974 < r² < 0.998. Limits of detection of the method (LOD) for all the standards were within the range 1.1-4,213 pg, as the absolute standard amount spiked into sorbent tubes in 1 μL standard mixture (dissolved in methanol).Overall results stated systematic correlation between waste’s nature and VOCs’ air composition. Organic wastes show main contribution of terpenes, waste water sludge residues’ of reduced sulphured compounds (RSCs) and municipal solid wastes show contribution of a wide sort of VOCs. The use of a chemometric approach for variable’s reduction to 12 principal components enables evaluation of similarities and dissimilarities between facilities. PCA clearly related samples to its corresponding facility on the basis of their VOCs composition and the ambient temperature.     

活性炭纤维低温脱除模拟烟气中的VOC

采用H2O2浸渍的修饰方法对ACF进行化学改性,并利用氮吸附等温线和XPS（X-ray photoelectron spectroscopy）的方法对ACF样品进行表征。通过在反应床上开展吸附实验,由此测定改性前后ACF脱除VOC（甲苯作为VOC的代表物）的效果,同时考察氧气、温度、水蒸气等因素对ACF脱除甲苯的影响。研究发现,改性使得ACF样品比表面积和孔容略有降低,但表面含氧官能团含量增加,吸附甲苯的能力也因此增强。当模拟烟气中O2浓度为5%时,ACF脱除VOC效果达到最佳,超过5%之后,氧的促进效果不再明显;温度40℃为最佳吸附温度;当烟气中加入水蒸气时,ACF对VOC的脱除效率降低。     

基于实地调研的广东省工业VOC排放清单改进研究

工业源是人为源挥发性有机物(VOC)排放的重要贡献源,然而现有基于统计年鉴数据建立的工业VOC排放清单仍然存在排放源缺失、排放量低估、空间分配精度不足等问题.为了提高清单表征及空间分配的精细度,本文在2014年基于统计年鉴数据建立的广东省工业VOC排放清单的基础上,利用问卷调研方式获取了12000多家工业企业的详细活动水平数据,对工业VOC排放表征与空间分配进行改进,进而建立了基于实地调研和统计年鉴数据相结合的2014年广东省工业VOC排放改进清单.结果表明,改进后广东省工业VOC清单排放量由500927 t增至716470 t,珠三角地区行业VOC排放量增加30%左右,非珠三角地区增加90%左右,其中,炼油及石化行业VOC排放量变化最为明显.改进前清单借助人口密度等空间地理信息为空间分配依据,导致部分VOC排放分配到工业源较少的居民区或市中心;改进后的空间分配优先采用基于经纬度信息的点源分配方法,点源调研数据使得分配后的工业VOC主要集中在工业园区,少数工业VOC排放分配给人类活动有限的偏远农村地区,分配结果更为合理、精细.利用CAMx模型结合实际观测站点监测结果评估此次改进对O_3生成的影响,总体上改进后清单提高了广州、东莞、惠州和茂名等城市的O_3峰值期的模拟浓度,降低了东莞及广州O_3污染时期的模拟偏差,部分被低估的模拟峰值可以提高6～9μg·m~(-3);同时,空间分配的改进也影响了城市间O_3传输模拟.     

加油站油类污染物自然衰减现场试验研究

利用自行设计制作的一套土壤气体取样监测装置,在北京地区某加油站开展了包气带内石油类污染物自然衰减的现场试验研究.在现场对包气带内的土壤气体样本进行采集,并对样本中的VOC含量及O2、CO2含量进行了检测分析.2个阶段的检测结果表明,经过381 d的自然衰减,污染点位的TVOC浓度减少了99.2%,BTEX的气相浓度占TVOC的比例由17.0%降至12.1%;O2和CO2含量在G3点位呈现出随着土壤深度的增加,O2含量逐渐减少、CO2含量逐渐增加的变化趋势.通过对试验结果的分析得出以下结论:①第一次检测结果表明G3点位附近存在一定的土壤污染,经过381 d的自然衰减,G3点位土壤中的BTEX含量已降至保护环境的标准以下,该污染现场的环境监控措施可以解除;②对造成该点污染的原因进行推断,可以判定污染为短期污染源导致,不存在持续的泄漏源;③自然衰减能够有效清除土壤中污染物,可以作为北京市同类污染场地有效的治理手段加以考虑;④检测污染土壤中O2和CO2含量的变化是判断有机污染物需氧降解的有效手段.     

Comparison of receptor models for source apportionment of volatile organic compounds in Beijing, China

Identifying the sources of volatile organic compounds (VOCs) is key to reducing ground-level ozone and secondary organic aerosols (SOAs). Several receptor models have been developed to apportion sources, but an intercomparison of these models had not been performed for VOCs in China. In the present study, we compared VOC sources based on chemical mass balance (CMB), UNMIX, and positive matrix factorization (PMF) models. Gasoline-related sources, petrochemical production, and liquefied petroleum gas (LPG) were identified by all three models as the major contributors, with UNMIX and PMF producing quite similar results. The contributions of gasoline-related sources and LPG estimated by the CMB model were higher, and petrochemical emissions were lower than in the UNMIX and PMF results, possibly because the VOC profiles used in the CMB model were for fresh emissions and the profiles extracted from ambient measurements by the two-factor analysis models were "aged".     

广佛公路(盐步段)两侧挥发性有机物(VOC)污染研究

选取广佛公路盐步路段作机动车尾气污染研究 ,结果表明 :污染物主要由烷烃、苯系物和氯代烃组成 ,主要是毒害性 VOC;污染随着与公路距离的增加而降低 ;污染源除机动车以外 ,还有大量的工业企业     

Underestimated contribution of fugitive emission to VOCs in pharmaceutical industry based on pollution characteristics, odorous activity and health risk assessment

Fugitive emission has been becoming an important source of volatile organic compounds (VOCs) in pharmaceutical industry, but the exact contribution of fugitive emission remains incompletely understood. In present study, pollution characteristics, odorous activity and health risk of stack and fugitive emissions of VOCs from four functional units (e.g., workshop, sewage treatment station, raw material storage and hazardous waste storage) of three representative pharmaceutical factories were investigated. Workshop was the dominant contributor to VOCs of fugitive emission in comparison with other functional units. Extreme high concentration of VOCs from fugitive emission in unsealed workshop (94.87 mg/m³) was observed relative to sealed one (1.18 mg/m³), accounting for 31% and 5% of total VOCs, respectively. Fugitive emission of VOCs in the unsealed workshop mainly consisted of n-hexane, 1-hexene and dichloromethane. Odorous activity indexes and non-cancer hazard ratios of these VOCs from fugitive emission in the unsealed workshop were as high as that from stack exhaust. Furthermore, cancer risk of dichloromethane from fugitive emission and stack exhaust was up to (1.6-1.8) × 10⁻⁵. Odorous activity or health risk index of the VOCs from fugitive emission was up to 13 or 11 times of the corresponding threshold value, posing remarkable health threat on pharmaceutical workers. Our findings highlighted the possibly underestimated contribution of fugitive emission on VOCs in the pharmaceutical industry.     

含VOC废气的回收净化工艺

针对目前国内VOC废气净化的现状 ,以吸附 冷凝回收原理为基础 ,采用集成了加热器和冷却器功能的新型吸附床及纤维活性炭 ,通过实验研究及实践应用 ,确定了纤维炭吸附 热力脱附 冷凝回收处理工艺。该工艺应用于高浓度、小风量的VOC废气处理 ,具有较好的经济效益和环境效益。