钍试剂分光光度法测定固定源烟气中SO3

以80%(体积分数)异丙醇为吸收液采集SO3后,用过量的Ba(ClO4)2与吸收液中SO42-反应,剩余Ba2 与钍试剂生成钍-钡络合物,测定该络合物在530 nm处的吸光度,由此间接计算出固定源烟气中SO3的浓度.钍试剂分光光度法对溶液SO42-测定范围为2.00～60.00 μg/mL,检出限为1.17 μg/mL.不同浓度样品的重复性实验和回收率检验结果证明了该法具有很好的精确度和准确度.样品中含有少量的Ca2 、Na 、K 、CO2-3、Cl-等,对测定结果无显著影响.     

Dilution-based emissions sampling from stationary sources: Part 1--Compact sampler methodology and performance

This paper presents the design and performance of a compact dilution sampler (CDS) for characterizing fine particle emissions from stationary sources. The sampler is described, along with the methodology adopted for its use. Dilution sampling has a number of advantages, including source emissions that are measured under conditions simulating stack gas entry and mixing in the ambient atmosphere. This is particularly important for characterizing the semivolatile species in effluents as a part of particulate emissions. The CDS characteristics and performance are given, along with sampling methodology. The CDS was compared with a reference dilution sampler. The results indicate that the two designs are comparable for tests on gas-fired units and a diesel electrical generator. The performance data indicate that lower detection limits can be achieved relative to current regulatory methods for particulate emissions. Test data for the fine particulate matter (PM2.5) emissions are provided for comparison with U.S. Environment Protection Agency (EPA) Conditional Test Method 040 for filterable particulate matter (FPM) and the EPA Method 202 for condensable particulate matter. This comparison showed important differences between methods, depending on whether a comparison is done between in situ FPM determinations or the sum of such values with condensable PM from liquid filled impingers chilled in an ice bath. These differences are interpretable in the light of semivolatile material present in the stack effluent and, in some cases, differences in detection and quantification limits. Determination of emissions from combustors using liquid fuels can be readily achieved using 1-hr sampling with the CDS. Emissions from gasfired combustors are very low, requiring careful attention to sample volumes. Sampling volumes corresponding with 6-hr operation were used for the combined mass and broad chemical speciation. Particular attention to dilution sampler operation with clean dilution air also is essential for gas-fired sources.     

An uncertainty analysis of mean flow velocity measurements used to quantify emissions from stationary sources

Point velocity measurements conducted by traversing a Pitot tube across the cross section of a flow conduit continue to be the standard practice for evaluating the accuracy of continuous flow-monitoring devices. Such velocity traverses were conducted in the exhaust duct of a reduced-scale analog of a stationary source, and mean flow velocity was computed using several common integration techniques. Sources of random and systematic measurement uncertainty were identified and applied in the uncertainty analysis. When applicable, the minimum requirements of the standard test methods were used to estimate measurement uncertainty due to random sources. Estimates of the systematic measurement uncertainty due to discretized measurements of the asymmetric flow field were determined by simulating point velocity traverse measurements in a flow distribution generated using computational fluid dynamics. For the evaluated flow system, estimates of relative expanded uncertainty for the mean flow velocity ranged from ±1.4% to ±9.3% and depended on the number of measurement locations and the method of integration.

Implications:Accurate flow measurements in smokestacks are critical for quantifying the levels of greenhouse gas emissions from fossil-fuel-burning power plants, the largest emitters of carbon dioxide. A systematic uncertainty analysis is necessary to evaluate the accuracy of these measurements. This study demonstrates such an analysis and its application to identify specific measurement components and procedures needing focused attention to improve the accuracy of mean flow velocity measurements in smokestacks.     

Aerostat-lofted instrument and sampling method for determination of emissions from open area sources

An aerostat-borne instrument and sampling method was developed to characterize air samples from area sources, such as emissions from open burning. The 10 kg battery-powered instrument system, termed “the Flyer”, is lofted with a helium-filled aerostat of 4 m nominal diameter and maneuvered by means of one or two tethers. The Flyer can be configured variously for continuous CO₂ monitoring, batch sampling of semi-volatile organic compounds (SVOCs), volatile organic compounds (VOCs), black carbon, metals, and PM by size. The samplers are controlled by a trigger circuit to avoid unnecessary dilution from background sampling when not within the source plume. The aerostat/Flyer method was demonstrated by sampling emissions from open burning (OB) and open detonation (OD) of military ordnance. A carbon balance approach was used to derive emission factors that showed excellent agreement with published values.     

Dilution-based emissions sampling from stationary sources: Part 2--Gas-fired combustors compared with other fuel-fired systems

With the recent focus on fine particle matter (PM2.5), new, self-consistent data are needed to characterize emissions from combustion sources. Such data are necessary for health assessment and air quality modeling. To address this need, emissions data for gas-fired combustors are presented here, using dilution sampling as the reference. The dilution method allows for collection of emitted particles under conditions simulating cooling and dilution during entry from the stack into the air. The sampling and analysis of the collected particles in the presence of precursor gases, SO2 nitrogen oxide, volatile organic compound, and NH3 is discussed; the results include data from eight gas fired units, including a dual-fuel institutional boiler and a diesel engine powered electricity generator. These data are compared with results in the literature for heavy-duty diesel vehicles and stationary sources using coal or wood as fuels. The results show that the gas-fired combustors have very low PM2.5 mass emission rates in the range of approximately 10(-4) lb/million Btu (MMBTU) compared with the diesel backup generator with particle filter, with approximately 5 x 10(-3) lb/MMBTU. Even higher mass emission rates are found in coal-fired systems, with rates of approximately 0.07 lb/MMBTU for a bag-filter-controlled pilot unit burning eastern bituminous coal. The characterization of PM2.5 chemical composition from the gas-fired units indicates that much of the measured primary particle mass in PM2.5 samples is organic or elemental carbon and, to a much less extent, sulfate. Metal emissions are quite low compared with the diesel engines and the coal- or wood-fueled combustors. The metals found in the gas-fired combustor particles are low in concentration, similar in concentration to ambient particles. The interpretation of the particulate carbon emissions is complicated by the fact that an approximately equal amount of particulate carbon (mainly organic carbon) is found on the particle collector and a backup filter. It is likely that measurement artifacts, mostly adsorption of volatile organic compounds on quartz filters, are positively biasing "true" particulate carbon emission results.     

An inexpensive method to estimate CO and NOx emissions from mobile sources

CO and NO_x measurements from mobile sources at two urban locations in Córdoba City, Argentina, were used to develop a very simple method to estimate emission from these sources. This development was possible because primary urban air pollution in Córdoba comes mostly from mobile sources and because a field measurement campaign was conducted by the city government during 1995–1996 that has allowed us to have a complete and valuable data bank. Air concentrations of CO, NO_x as well as physical, and meteorological variables were measured at two urban sites with two monitoring stations. We compared the measured CO and NO_x air concentration data with the predictions of a method that uses regression analysis to estimate the emission factor from the mobile sources. The agreement is good, considering the simplicity of the approach.     

Characterization of emissions from a variable gasoline/methanol fueled car.

In response to the occurrence of the increasingly severe ambient ozone exceedances, regional environmental managers are examining the possibility of a cleaner fuel for automobiles. At this time the leading candidate appears to be methanol. In anticipation of a shift to methanol, flexible-fueled automobiles capable of operating on gasoline and/or methanol are being developed. This study examines both the exhaust and evaporative emissions from a prototype General Motors Variable Fuel Corsica. Results are reported for tests conducted at temperatures of 40 degrees, 75 degrees, and 90 degrees F, and for fuels M0 M25, M50, M85, and M100. In addition to regulated emissions and fuel economy, emission rates for methanol, aldehydes, and a large number of hydrocarbon compounds were measured. The data indicate that increasing the fuel's methanol content does not affect the exhaust organic emission rate (calculated in accordance with the regulation) from flexible-fueled cars, but formaldehyde and methanol comprise increasingly greater portions of the organic material while hydrocarbons comprise less. Increasing fuel methanol content has no significant effect on exhaust regulated emission rates (organic material, carbon monoxide, and nitrogen oxides) nor on the composition of total hydrocarbons, except for methane, which increases substantially. The effect of ambient temperature on both exhaust and evaporative emissions is similar to its effect on gasoline cars: organic and carbon monoxide exhaust emissions increase substantially at the lower temperatures, and evaporative emissions increase steadily with increases in temperature.     

Design of a compact dilution sampler for stationary combustion sources

The dilution sampling method simulates the rapid cooling and dilution processes after hot flue gas have left the stack. This allows gases or vapors to nucleate both homogeneously and heterogeneously, and to condense on preexisting particles in processes analogous to those that occur in the ambient environment. Using this method the authors can collect filterable particulate matter (PM) and condensible PM, that is, primary PM, simultaneously. In order to make this method more suitable for field investigation, a compact dilution sampler was developed. The sampler enhances mixing of dilution air with the stack gas, and thus shortens the length of the mixing section. The design decreases the nominal flow rate through the aging section, and accordingly reduces the size of the residence chamber. The decreased size of the sampler is suitable for field test. Sampling gas is pressured into the residence chamber, and air pressure in the chamber is micro-positive. Uncollected redundant gas is automatically discharged through unused sampling ports, which keeps the unit stable. Performance evaluation tests demonstrate that the design is reasonable. The sampler has been applied to characterize PM emissions from various combustion sources in China.     

Bisphenol A: emissions from point sources

Bisphenol A is widely used for the production of epoxy resins and polycarbonate plastics. Special in vitro test systems and animal experiments showed a weak estrogenic activity for Bisphenol A. Based on in vitro receptor interaction studies, the activity was estimated to be 2 x 10(-3) lower than that of estradiol. Especially aquatic wildlife could be endangered by waste water discharges. To manage possible risks arising from Bisphenol A contamination, the major fluxes need to be obtained and the contributors to the contamination of municipal treatment plants need to be determined. In this study, industrial emitters and communal waste waters were monitored simultaneously. Mixed samples were taken over periods of one week at nine sample sites. The results showed that the concentrations and fluxes were variable. The paper industry was the major Bisphenol A contributor to the influent of the waste water treatment plant. All the other fluxes measured, including two household areas, were considerably low. About 90% of the total load was removed during the waste water treatment.     

Atmospheric emissions of mercury from Australian point sources

The UN Global Mercury Assessment (GMA) estimates that atmospheric emissions of mercury from Australian stationary combustion sources were 97.0 tonnes for the year of 1995. This is more than 90% of the estimated emissions from stationary combustion for the whole of North America, and seems abnormally high for a country with a population of around 20 million, in spite of the fact that most of Australia's stationary energy supply is provided by coal. It is also significantly larger than previous estimates of mercury emissions from Australian sources. New estimates of Australian mercury emissions from stationary energy sources, based on both a top down and bottom up approach, are presented. These estimates can be reconciled for black coal fired power stations, but suggest that the bottom up approach (the Australian National Pollutant Inventory) significantly under-estimates emissions from brown coal fired plant, if mercury capture efficiencies in these plants are low, as observed for lignite-fired plant. The major uncertainties in these estimates are the coal mercury content in coals burnt in Australian power stations, and the mercury capture efficiency in particulate control devices used at these stations. Based on these estimates, Australian emissions of mercury from stationary energy are currently 2–8 tonnes/year, significantly lower than the GMA estimate.     

Direct measurement of fugitive emissions of hydrocarbons from a refinery

Refineries are a source of emissions of volatile hydrocarbons that contribute to the formation of smog and ozone. Fugitive emissions of hydrocarbons are difficult to measure and quantify. Currently these emissions are estimated based on standard emission factors for the type and use of equipment installed. Differential absorption light detection and ranging (DIAL) can remotely measure concentration profiles of hydrocarbons in the atmosphere up to several hundred meters from the instrument. When combined with wind speed and direction, downwind vertical DIAL scans can be used to calculate mass fluxes of the measured gas leaving the site. Using a mobile DIAL unit, a survey was completed at a Canadian refinery to quantify fugitive emissions of methane, C2+ hydrocarbons, and benzene and to apportion the hydrocarbon emissions to the various areas of the refinery. Refinery fugitive emissions as measured with DIAL during this demonstration study were 1240 kg/hr of C2+ hydrocarbons, 300 kg/hr of methane, and 5 kg/hr of benzene. Storage tanks accounted for over 50% of the total emissions of C2+ hydrocarbons and benzene. The coker area and cooling towers were also significant sources. The C2+ hydrocarbons emissions measured during the demonstration amounted to 0.17% of the mass of the refinery hydrocarbon throughput for that period. If the same loss were repeated throughout the year, the lost product would represent a value of US$3.1 million/yr (assuming US$40/bbl). The DIAL-measured hourly emissions of C2+ hydrocarbons were 15 times higher than the emission factor estimates and gave a different perspective on which areas of the refinery were the main source of emissions. Methods, such as DIAL, that can directly measure fugitive emissions would improve the effectiveness of efforts to reduce emissions, quantify the reduction in emissions, and improve the accuracy of emissions data that are reported to regulators and the public.     

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。     

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.     

Particulate emissions from a stationary engine fueled with ultra-low-sulfur diesel and waste-cooking-oil-derived biodiesel

Stationary diesel engines, especially diesel generators, are increasingly being used in both developing countries and developed countries because of increased power demand. Emissions from such engines can have adverse effects on the environment and public health. In this study, particulate emissions from a domestic stationary diesel generator running on ultra-low-sulfur diesel (ULSD) and biodiesel derived from waste cooking oil were characterized for different load conditions. Results indicated a reduction in particulate matter (PM) mass and number emissions while switching diesel to biodiesel. With increase in engine load, it was observed that particle mass increased, although total particle counts decreased for all the fuels. The reduction in total number concentration at higher loads was, however, dependent on percentage of biodiesel in the diesel-biodiesel blend. For pure biodiesel (B100), the reduction in PM emissions for full load compared to idle mode was around 9%, whereas for ULSD the reduction was 26%. A large fraction of ultrafine particles (UFPs) was found in the emissions from biodiesel compared to ULSD. Nearly 90% of total particle concentration in biodiesel emissions comprised ultrafine particles. Particle peak diameter shifted from a smaller to a lower diameter with increase in biodiesel percentage in the fuel mixture.     

我国移动源主要大气污染物排放量的估算

在考虑我国移动源主要大气污染物排放标准变化的基础上,分别对我国2000-2012年道路移动源和非道路移动源主要大气污染物（CO、NOx、HC、PM2.5）的排放量进行了估算。研究表明：2000-2012年间,我国移动源主要大气污染物排放总量呈现先增后减的趋势,2005年达到最大值,为4 233万t,其中道路移动源的排放量占80%以上;各类大气污染物的排放量的差异性较大,CO和NOx的排放量较多,占排放总量的87%以上,从整体趋势上来看,CO的排放量逐年较少,NOx的排放量逐年增大,而HC和PM2.5变化不大;摩托车和重型柴油货车是道路移动源主要排放源,农业机械是非道路移动源的主要排放源;移动源排放的主要大气污染物在地区间的分布极不平衡,2012年排放量最高的5个省份依次是山东、河北、河南、广东和江苏;排放强度较大的地区主要集中在环渤海经济圈、长三角地区和珠三角地区,其中又以上海、北京、天津3个直辖市的排放强度最大。     

A novel field measurement method for determining fine particle and gas emissions from residential wood combustion

Emission data from residential wood combustion are usually obtained on test stands in the laboratory but these measurements do not correspond to the operational conditions in the field because of the technological boundary conditions (e.g. testing protocol, environmental and draught conditions). The field measurements take into account the habitual practice of the operators and provide the more reliable results needed for emission inventories. In this study, a workable and compact method for measuring emissions from residential wood combustion in winter conditions was developed. The emissions for fine particle, gaseous and PAH compounds as well as particle composition in real operational conditions were measured from seven different appliances. The measurement technique worked well and was evidently suitable for winter conditions. It was easy and fast to use, and no construction scaffold was needed. The dilution of the sample with the combination of a porous tube diluter and an ejector diluter was well suited to field measurement. The results indicate that the emissions of total volatile organic carbon (TVOC) (17 g kg⁻¹ (of dry wood burned)), carbon monoxide (CO) (120 g kg⁻¹) and fine particle mass (PM₁) (2.7 g kg⁻¹) from the sauna stove were higher than in the other measured appliances. In the masonry heaters, baking oven and stove, the emissions were 2.9–9 g kg⁻¹ TVOC, 28–68 g kg⁻¹ CO and 0.6–1.6 g kg⁻¹ PM₁. The emission of 12 PAHs (PAH₁₂) from the sauna stove was 164 mg kg⁻¹ and consisted mainly of PAHs with four benzene rings in their structure. PAH₁₂ emission from other appliances was, on average, 21 mg kg⁻¹ and was dominated by 2-ring PAHs. These results indicate that despite the non-optimal operational practices in the field, the emissions did not differ markedly from the laboratory measurements.     

A fluctuating plume dispersion model for the prediction of odour-impact frequencies from continuous stationary sources

A fluctuating plume dispersion model has been developed to facilitate the prediction of odour-impact frequencies in the communities surrounding elevated point sources. The model was used to predict the frequencies of occurrence of odours of various magnitudes for 1 h periods. In addition, the model predicted the maximum odour level. The model was tested with an extensive set of data collected in the residential areas surrounding the paint shop of an automotive assembly plant. Most of the perceived odours in the vicinity of the 64, 46 m high stacks ranged between 2 and 7 odour units and generally persisted for less than 30 s. Ninety-eight different field determinations of odour impact frequencies within 1 km of the plant were conducted during the course of the study. To simplify evaluation, the frequencies of occurrence of different odour levels were summed to give the total frequency of occurrence of all readily detectable (>2 OU) odours. The model provided excellent simulation of the total frequencies of occurrence where the odour was frequent (i.e. readily detectable more than 30% of the time). At lower frequencies of occurrence the model prediction was poor. The stability class did not seem to affect the model's ability to predict field frequency values. However, the model provided excellent predictions of the maximum odour levels without being sensitive to either stability class or distance from the source. Ninety-five percent of the predicted maximum values were within a factor of two of the measured field maximum values.