加油站油气扩散与回收效果的数值分析

加油站排放出的油气是有毒有害的气体。目前控制油品蒸发损耗的有效方法是采用油气回收系统。基于湍流模式理论，采用FLUENT软件，模拟加油站在使用油气回收系统前后空气中油气浓度分布情况及风对油气扩散的影响，得到油气浓度等值面图、直线及点上浓度变化曲线图。模拟结果表明，实施油气回收，其大气净化率可高达95％以上，因此明显减小加油站火灾隐患及环境污染，并可减少经济损失及节约加油站占地面积。另外，风对油气扩散稀释有明显的影响，如距排放口下风侧5 m处，相对于风速１ m/s，风速为5、8 m/s时的大气净化率分别为54％、71％。虽然无法降低油气排放总量，但是随着风速的增加大气净化率随之变大，可以减少油气浓度值过高造成的危害。     

四川省加油站挥发性有机物排放及控制现状

四川省汽车保有量2017年位列全国第7位,油品储运销过程中挥发性有机物(VOCs)排放压力巨大。利用排放因子法,结合四川省4 492座加油站的油品销售量,编制了四川省2017年加油站VOCs排放清单。另一方面,对四川省不同片区的VOCs排放特征及油气回收关键参数进行了现场实测。结果表明:四川省加油站VOCs排放量共12 294.54t,排放区域主要集中在成都市、绵阳市和宜宾市等地区;四川省四大片区VOCs排放浓度,加油环节攀西片区最高,达到7 076.86μg/m~3,卸油环节川东北片区最高,达到9 638.53μg/m~3,均是其他片区的2～3倍,加油和卸油环节排放的异戊烷最高占比(质量分数)可分别达到70.1%和67.4%;四川省油气回收系统达标情况仍然比较严峻,不达标率高达47%,密闭性和气液比不达标率尤为显著,集中式油气回收系统不达标率高于分散式。     

加油站的烃类VOCs污染及其治理技术

加油站因储运轻质油品而产生的烃类VOCs对健康、环境、安全以及油品质量等带来了一系列负面影响.发达国家的常规治理措施主要是进行密闭卸油和密闭发油,对加油站的设备安装、管线布置、运营管理等都有一些具体要求;进入21世纪后美国又提出了强化加油站油气回收处理的观点,相应的技术、设备及法规也都日益健全.国内目前对加油站烃类VOCs污染的治理工作与发达国家相比差距很大,应该尽快从烃类VOCs回收处理的专用膜分离装置入手进行相关研究和产品开发.     

固定源氮氧化物排放及控制技术应用

固定源是氮氧化物排放的一个主要来源。通过对主要固定源氮氧化物生成机理及现有的排放控制技术进行论述，分析我国固定源氮氧化物排放的实际情况，提出我国固定源氮氧化物排放控制还处于起步阶段，氮氧化物排放标准相对宽松，氮氧化物排放控制技术有待进一步普及，并提出固定源氮氧化物排放治理的一些建议。     

基于玻璃态膜组件的油气污染排放控制技术研究

针对加油站收油和发油过程中产生的油气污染，采用新型的玻璃态油气截留型PEEK中空纤维膜组件，在自行设计建造的膜分离设备上，分别考察了膜组件和整个膜系统对油气污染治理和回收的效果，提出了一种研究膜法油气回收过程的新思路。对于膜组件的分离实验结果发现，处理流量在2.5～7.5 m3/h、系统压力在525～825 Pa之间的...     

小型燃油锅炉NOx的排放特征与管理控制

以68台燃油锅炉（≤10.5 MW）NO_x排放实测数据为基础，通过统计分析方法，研究了NO_x的排放特征；通过对比分析，探讨了我国燃油锅炉NO_x排放控制与管理现状，讨论了进一步加强我国燃油锅炉NO_x排放管理控制的可能性与可行性，并提出了相应的管理控制建议。结果表明，NO_x平均排放浓度为318.2 mg/m³，     

电化学氧化法深度处理垃圾焚烧发电厂沥滤液生化出水

垃圾焚烧发电厂的沥滤液经生化处理后，COD和色度等仍然较高，达不到排放标准，必须进一步进行深度处理。采用自制的箱式四通道电化学反应器对垃圾焚烧发电厂沥滤液生化出水进行深度处理，研究了主要工艺参数——电流密度、表观流速、初始Cl^-浓度、比电极面积等因素对COD和色度去除效果的影响。适宜处理条件为：电流密度20 mA/cm²，反应器内表观流速2.92 cm/s，初始Cl^-浓度4 732 mg/L、比电极面积43.4 m²/m³。在此条件下处理废水10 min，色度就能达到排放要求，处理2 h，COD也能达到排放要求。考察反应器的能耗发现，电化学处理的能耗随电化学处理时间的延长呈不断增大的趋势。     

固定源氮氧化物排放及控制技术应用

固定源是氮氧化物排放的一个主要来源.通过对主要固定源氮氧化物生成机理及现有的排放控制技术进行论述,分析我国固定源氮氧化物排放的实际情况,提出我国固定源氮氧化物排放控制还处于起步阶段,氮氧化物排放标准相对宽松,氮氧化物排放控制技术有待进一步普及,并提出固定源氮氧化物排放治理的一些建议.     

加油站气液比检测方法及其影响

气液比(A/L)是加油站油气回收系统的一项重要控制指标,利用A/L测试仪、光离子化VOCs检测仪和油气排放因子测试装置,研究了不同A/L检测连接方式对A/L检测结果、检测人员暴露浓度、油气排放和油气回收效率等的影响。结果表明,不同连接方式和是否预先向检测油桶注油会导致A/L检测结果不一致,如果油桶与流量计不连接,A/L检测值将是实际A/L的1.04倍,当按照A/L=1.00~1.20调整加油枪A/L时,实际A/L将在0.96~1.15之间;按照国标GB20952-2007连接方式检测A/L可以减少检测过程中约80%的加油油气排放,夏季检测人员暴露油气浓度将由451×10-6(体积浓度)下降至91×10-6(体积浓度),油气排放因子将由1 056 mg/L下降至242 mg/L,更可减少因油罐吸入空气造成额外的汽油挥发排放,但不能减少倒油油气排放。     

脉冲电絮凝处理电镀含铬废水的实验研究

常规方法处理电镀废水都有较明显的缺陷，而脉冲电絮凝技术在处理效果、运行成本及可操作性方面有较大的优势。实验表明，当调节进水pH＝4、极板间电压为2.5 V，停留时间(HRT)为15 min，电流密度为25 A/m²时，系统处于最佳状态，铬离子去除率保持在99.5％以上，达到排放标准。     

Determination and impact of volatile organics emitted during rush hours in the ambient air around gasoline stations

This study analyzes the volatile organic compounds (VOCs) in the ambient air around gasoline stations during rush hours and assesses their impact on human health. Results from this study clearly indicate that methyl tertiary butyl ether (MTBE), toluene, and isobutane are the major VOCs emitted from gasoline stations. Moreover, the concentrations of MTBE and toluene in the ambient air near gasoline stations are remarkably higher than those sampled on surrounding roads, revealing that these compounds are mainly released from gasoline stations. The concentration of VOCs near the gasoline stations without vapor recovery systems are approximately 7.3 times higher than those around the gasoline stations having the recovery systems. An impact on individual health and air quality because of gasoline station emissions was done using Integrated Risk Information System and Industrial Source Complex Short Term model.     

Determination and Impact of Volatile Organics Emitted during Rush Hours in the Ambient Air around Gasoline Stations

Abstract

This study analyzes the volatile organic compounds (VOCs) in the ambient air around gasoline stations during rush hours and assesses their impact on human health. Results from this study clearly indicate that methyl tertiary butyl ether (MTBE), toluene, and isobutane are the major VOCs emitted from gasoline stations. Moreover, the concentrations of MTBE and toluene in the ambient air near gasoline stations are remarkably higher than those sampled on surrounding roads, revealing that these compounds are mainly released from gasoline stations. The concentration of VOCs near the gasoline stations without vapor recovery systems are ～7.3 times higher than those around the gasoline stations having the recovery systems. An impact on individual health and air quality because of gasoline station emissions was done using Integrated Risk Information System and Industrial Source Complex Short Term model.     

膜分离技术在油气回收中的应用

简单阐述了油气回收的意义,并对几种常用的油气回收方法进行了介绍,分析其优缺点,重点论述了膜分离技术在油气回收中的应用,以及国内外的进展情况和典型应用实例,最后对膜法油气回收与其它方法作了比较,对膜法回收现阶段的存在问题进行了剖析,并对今后的研究方向提出了建议。研究结果表明,膜法是一种大有前途的油气回收方法。     

Comparison of Spill Frequencies and Amounts at Vapor Recovery and Conventional Service Stations in California

Based on a survey conducted in 1989 and 1990 at 21 conventional nozzle and 33 vapor recovery nozzle equipped service stations in California, the California Air Resources Board staff conclude that conventional nozzles in California produce a greater number of quantifiable spills (≥1 ml) and a greater average volume per spill than do vapor recovery equipped nozzles. This conclusion is based on survey results showing conventional nozzles having spills 30.3 percent of the time at four fueling intervals vs 22.3 percent for vapor recovery nozzles, and having an average spill volume of 13.3 ml vs 10.6 ml for vapor recovery nozzles. However, if spillage noted from a conventional nozzle during a very large spill event is subtracted from the total quantified spill volume, the average volume per quantifiable spill for a conventional nozzle would drop to 11.0 ml. This value is very close to the 10.6 ml average volume per quantifiable spill with a vapor recovery nozzle. In addition, conventional nozzles in California produce about 14 percent more drop (<1 ml) spillage than do vapor recovery nozzles. Drop spillage has not been quantified as to the volume of gasoline it represents.     

Transportation-Related Volatile Hydrocarbon Source Profiles Measured in Atlanta

Abstract

Samples representative of transportation-related hydrocarbon emissions were collected as part of the 1990 Atlanta Ozone Precursor Monitoring Study. Motor vehicle emissions were sampled in canisters beside a roadway in a tunnel-like underpass during periods of heavy traffic. Airport and aircraft emissions were approximated by canister samples obtained at a major airport facility. Three octane grades of gasoline were purchased from six major vendors in Atlanta. Canister samples were prepared using these fuels to approximate the whole gasoline and gasoline vapor composition of the fuels in use during the study. All samples were analyzed by gas chromatography/flame ionization detection (GC/FID) for their hydrocarbon content. Detailed speciated hydrocarbon profiles were developed from this source sampling and analysis program for use in the Chemical Mass Balance (CMB) model. Profiles presented and discussed here represent the hydrocarbon composition of emissions from a roadway, composite headspace gasoline at two temperatures, composite whole gasoline, whole gasoline at three octane grades, and an airport. The roadway profile is compared with similar profiles in the literature, and recommendations are made regarding its use in the CMB model. The roadway and fuel profiles are discussed in the context of the MOBILE5 model outputs. The headspace gasoline vapor profile presented here is compared with a headspace gasoline vapor profile calculated from the whole gasoline profile by means of Raoult’s law. Agreement between the measured and calculated headspace profiles is excellent. The airport profile demonstrates the importance of high molecular weight volatile hydrocarbons in airport and aircraft emissions.     

Chemical composition of major VOC emission sources in the Seoul atmosphere

This paper describes a chemical analysis of volatile organic compounds (VOCs) for five emission sources in Seoul. The source categories included motor vehicle exhaust, gasoline evaporation, paint solvents, natural gas and liquefied petroleum gas (LPG). These sources were selected because they have been known to emit significant quantities of VOCs in the Seoul area (more than 5% of the total emission inventory). Chemical compositions of the five emission sources are presented for a group of 45 C2-C9 VOCs. Motor vehicle exhaust profiles were developed by conducting an urban tunnel study. These emissions profiles were distinguished from the other emission profiles by a high weight percentage of butanes over seasons and propane in the wintertime. It was found that this is due to the wide use of butane-fueled vehicles. To obtain gasoline vapor profiles, gasoline samples from five major brands for each season were selected. The brands were blended on the basis of the marketshare of these brands in Seoul area. Raoult's law was used to calculate gasoline evaporative compositions based on the liquid gasoline compositions. The measured and estimated gasoline vapor compositions were found to be in good agreement. Vehicle and gasoline evaporation profiles were made over seasons because of the seasonal change in their compositions. Paint solvent emissions profiles were produced based on a product-use survey and sales figures. These profiles are a composite of four major oil-based paints and thinning solvent. The source profile of natural gas was made on a methane-free basis. It was found that Ethane and propane were the most abundant compounds accounting for 95% of the natural gas composition. LPG was largely composed of propane and ethane and the remaining components were minor contributors.     

A Chemical Mass Balance for Volatile Organics in Chicago

Increasing attention to the presence of atmospheric volatile organic compounds has focused interest on the sources and fate of organics in ambient air. The purpose of this study was to develop a chemical mass balance receptor model (CMB) to determine the contributions of major organic pollution source types to ambient pollution levels. Twenty mid-day ambient air samples were analyzed for the presence of volatile hydrocarbons by gas chromatographlc procedures. Based on these measurements, contributions from vehicles, gasoline vapor emissions, and petroleum refineries to ambient organic concentrations were estimated. For the receptor site studied, vehicles were the dominant source type and accounted for 60.8 percent of the organics evaluated. Contributions from refineries, gasoline vapor, and all other sources were 10.1, 11.1, and 17.9 percent, respectively. Validation of the predictions showed that the model is sensitive to the effect of overall upwind emissions. The CMB model was shown to produce reasonable predictive results for vehicles, gasoline vapor, and refinery contributions to ambient non-methane organic concentrations.     

Effect of gas velocity and influent concentration on biofiltration of gasoline off-gas from soil vapor extraction

This study was conducted to evaluate the effects of gas inlet concentration and velocity on the biofiltration of gasoline vapor. Gasoline vapor was treated using a compost biofilter operated in an upflow mode for about 3 months. The inlet concentration of gasoline total petroleum hydrocarbon (TPH) ranged from about 300 to 7000 mgm(-3) and gas was injected at velocities of 6 and 15 mh(-1) (empty bed residence time (EBRT)=10 and 4 min, respectively). The maximum elimination capacities of TPH at 6 and 15 mh(-1) found in this research were over 24 and 19 gm(-3) of filling material h(-1), respectively. TPH removal data was fit using a first-order kinetic relationship. In the low concentration range of 300-3000 mg m(-3), the first-order kinetic constants varied between about 0.10 and 0.29 min(-1) regardless of gas velocities. At TPH concentrations greater than 3000 mgm(-3), the first-order kinetic constants were about 0.09 and 0.07 min(-1) at gas velocities of 6 mh(-1) and 15 mh(-1), respectively. To evaluate microbial dynamics, dehydrogenase activity, CO2 generation and microbial species diversity were analyzed. Dehydrogenase activity could be used as an indicator of microbial activity. TPH removal corresponded well with CO2 evolution. The average CO2 recovery efficiency for the entire biofilter ranged between 60% and 70%. When the gas velocity was 6 mh(-1), most of the microbial activity and TPH removal occurred in the first quarter of the biofilter. However, when the gas velocity was 15 mh(-1), the entire column contributed to removal. Spatial and temporal variations in the biofilter microbial population were also observed. Nearly 60% of the colonies isolated from the compost media prior to biofiltration were Bacillus. After 90 days of biofiltration, the predominant species in the lower portion (0-50 cm) of the filter were Rhodococcus, while Pseudomonas and Acinetobacter dominated the upper portion (75-100 cm).