On the difference between SO2−4 and NO−3 in wintertime precipitation

Winter rains have lower NO⁻₃ levels but higher SO²⁻₄ levels than snows in the NE United States. In this study, four years of winter precipitation data from SE Michigan were examined to help understand these differences. Although NO⁻₃ levels were indeed higher in snow than winter rain, the higher concentrations could be attributed to the generally lower precipitation depths associated with snow events than with rain events. The NO⁻₃ concentrations are inversely correlated with precipitation depth. There was no evidence that snow scavenged HNO₃ in the air more efficiently than rain.Conversely, SO²⁻₄ was far higher in winter rain than in snow. This could not be explained in terms of ground-level ambient S concentrations or the wind direction from which the storm originated. However, the cloud temperatures were high enough in the case of rain to suggest that the cloud hydrometeors could have been present as liquid droplets rather than ice crystals. The SO²⁻₄ concentrations of the precipitation were highly correlated with the temperatures of the cloud layers. The data suggest that SO₂ is incorporated and oxidized to SO²⁻₄ in clouds most efficiently when the hydrometeors are present as liquid droplets. The fact that NO⁻₃does not show the same relationship suggests that incorporation of N species into cloud water followed by oxidation is not as important a process for N as for S.     

Na-Ba/γ-Al2O3的NO和SO2吸附性能研究

研究了Na-Ba/γ-Al2O3吸附催化剂上NO和SO2的吸附-脱附性能.Na、Ba质量分数分别为6.2%、5.4%,焙烧温度和焙烧时间分别为600 ℃和10 h,吸附温度为100 ℃,其对NO、SO2的最大吸附量分别为0.052 4、0.344 mmol/g.同时考察了添加第三活性组份的影响,结果表明,Fe最为有效,Na-Ba/Fe/γ-Al2O3的NO、SO2最大吸附量分别为0.062 4、0.486 mmol/g.漫反射红外光谱研究结果表明,Fe降低了硫酸盐分解温度,促进吸附催化剂的再生.     

An evaluation of artifact SO42− formation on nylon filters under field conditions

The extent of SO₂ conversion on Membrana (Ghia) Nylasorb nylon filters under field conditions has been evaluated and found to be quite variable. The S-SO₄²⁻ loading on the nylon filters is higher at higher SO₂ concentrations, and on a long term basis approaches a saturatio limit of 2.5 μg S-SO₄²⁻ on a 47mm disc, at a dosage of 230 μg SO₂ approximately. The % conversion decreases as the SO₂ concentration increases. On a long term basis, at an SO₂ concentration range of 1.0–7.7 μg m⁻³, the conversion ranges from 8.2% to 2.1%. The dependence of SO₂ conversion on nylon filters on relative humidity displays a diurnal pattern. An expression has been derived to explain the observed % SO₂ conversion on nylon filters as a combined effect of the ambient SO₂ concentration and relative humidity.     

H2O和SO2对V2O5-WO3/TiO2催化剂催化氧化NO的影响

研究了在120℃的反应温度下,H2O和SO2对V2O5-WO3TiO2催化剂选择性催化氧化(SCO)NO的影响.结果表明,在H2O和SO2存在的情况下催化剂失活很快,停止通入H2O和SO2后活性不能恢复,但在加热到250℃后催化活性基本恢复.FT-IR分析表明,催化剂表面形成了金属硝酸盐和Ti的硫酸盐,对催化活性有一定...     

H2O和SO2对V2O5-WO3/TiO2催化剂催化氧化NO的影响

研究了在120℃的反应温度下,H2O和SO2对V2O5-WO3/TiO2催化剂选择性催化氧化（SCO）NO的影响。结果表明,在H2O和SO2存在的情况下催化剂失活很快,停止通入H2O和SO2后活性不能恢复,但在加热到250℃后催化活性基本恢复。FT-IR分析表明,催化剂表面形成了金属硝酸盐和Ti的硫酸盐,对催化活性有一定影响,但不影响催化剂在250℃下催化活性的恢复。SO2、H2O和NO的竞争吸附与SO2和NO2的铅室反应是影响催化剂活性的主要原因。     

The climatology of summertime O3 and SO2 (1977–1981)

The mean monthly distribution of the diurnal maximum O₃ and of the SO₂ in the eastern two-thirds of the U.S. was determined for the summer (July and August) of 1977–1981. Highest O₃ concentrations varied from 60 to 90 ppbv and covered an area of about 2 to 5 × 10⁶ km²; and that for SO₂ varied from values greater than 10 ppbv to values about 25 ppbv and covered an area of 0.3–1.3 × 10⁶ km². The geographical locations of the centers of high O₃ concentrations were related to the path of the anticyclones. The centers of high SO₂ concentration were affected by the path of anticyclones but to a lesser extent. The SO₂ distribution was controlled to a significant extent by the location of major SO₂ sources. The data suggested that highpressure systems that become stationary, weaken and dissipate in the eastern two-thirds of the U.S. have a profound effect on the O₃ and SO₂ distribution.     

AA3自动分析仪测定地表水中的NO2-N、NO3-N＋NO2-N、NH3-N、PO4^3-

使用Bran＋Luebbe AutoAnalyzer 3自动分析仪，同时测定地表水中的NO2-N、NO3-N＋NO2-N、NH3-N、PO4^3-4个项目，结果显示相对标准偏差均〈1％，回收率在92％～108％之间，检测限较低，且系统运行稳定，能够满足地表水监测的要求。     

SO2、NO对汞在湿法电除尘器中脱除的影响

湿法电除尘器(WESP)作为一种控制烟气中超细颗粒物的有效手段被应用于燃煤电厂的超低排放改造中,然而烟气中的Hg~0受电场、水膜、烟气组分等因素的影响在WESP中的协同脱除机理尚不明确。为了深入了解该机理,探讨了WESP电场和水膜对Hg~0的控制机理,并进一步研究了烟气中SO_2、NO对Hg~0在WESP中脱除的影响。结果表明:电场静电作用对烟气中Hg~0脱除贡献较小,O_2电离产物?O对Hg~0的氧化作用是O_2促进Hg~0脱除的主要途径,水蒸气通过电离产生?OH促进Hg~0氧化以及通过黏附作用促进Hg~0脱除;水膜的裹挟作用对WESP系统Hg~0的脱除贡献较小,溶于水中的汞不稳定且容易再释放;SO_2、NO均通过在电场中电离产生?O促进Hg~0氧化脱除,其中,SO_2及其电离产物溶于水膜后可以与Hg~(2+)形成稳定配合物抑制汞的再释放,而NO的电离产物在水膜中对汞再释放的抑制作用较小。     

脉冲电晕非平衡等离子体对烟气SO2、NO的氧化脱除

高压窄脉冲流注电晕放电的非平衡等离子体脱硫脱硝是开发中先进的燃煤烟气净化技术。采用模拟烟气和自行研制的脉冲电源及反应器，研究脉冲电晕对ＳＯ２、ＮＯ氧化脱除机理和规律。结果表明，正脉冲电晕将ＳＯ２、ＮＯ氧化成相应的酸很有效，远优于负脉冲电晕；正脉冲电晕氧化ＳＯ２、ＮＯ的能量利用率分别为６４．３ｇ．ＳＯ２／ｋｗｈ和９．９ｇ．ＮＯ／ｋｗｈ；加入氨水能有效地改善脱硫脱硝效率和能量利用率；温度对ＳＯ２、ＮＯ     

Recovering CO2 From Large− and Medium-Size Stationary Combustors

This paper summarizes the results of research conducted at Ar-gonne National Laboratory (ANL) to develop and design a novel method for the recovery of CO₂ from flue gases. The basic process concept Involves the combustion of a hydrocarbon fuel using a mixture of oxygen and carbon dioxide (or CO₂ and H₂0) rather than air as the oxidant, which results In a product stream that contains primarily CO₂ and H₂O. This stream Is then dried and conditioned to meet the specifications of the end user, A slip stream of CO₂ (or CO₂, and H₂0) is used as a diluent in the combustion chamberto maintain a flame temperature equivalent to the temperature that would otherwise be obtained using air as an oxidant. The cost-effectiveness of the process in recovering C0₂ is dependent on the scale of the operation, the type of fuel used, the cost of oxygen, and the cost of capital. The sensitivity of the cost of the recovered C0₂ to these variables Is discussed, and a model for estimating the cost of CO₂ recovered using the ANL process Is presented.     

Evidence of the water-cage effect on the photolysis of NO3− and FeOH2+. Implications of this effect and of H2O2 surface accumulation on photochemistry at the air–water interface of atmospheric droplets

Experiments are conducted to determine the effect of a cage of water molecules on the photolysis quantum yields of nitrate, FeOH²⁺, and H₂O₂. Results suggest that the quantum yields of nitrate and FeOH²⁺ are decreased by the recombination of photo-fragments ( OH +  NO₂ and Fe²⁺ +  OH, respectively) before they leave the surrounding cage of water molecules. However, no evidence is found for an enhanced quantum yield for H₂O₂. Therefore, the photolysis of nitrate and FeOH²⁺ could be enhanced if the cage of the solvent molecules is incomplete, as is the case at the air–water interface of atmospheric droplets. The photolysis rate constant distribution within nitrate, FeOH²⁺, and H₂O₂ aerosols is calculated by combining the expected quantum yield data in the bulk and at the interface with Mie theory calculations of light intensity. The photolysis rate constant of nitrate and FeOH²⁺ would be significantly higher at the surface than in the bulk if quantum yields are enhanced at the surface. In the case of H₂O₂, the photolysis rate constant would be enhanced by surface accumulation. The results concerning the expected rates of photolysis of these photoactive species are applied to the assessment of the reaction between benzene and OH in the presence of OH scavengers in an atmospherically relevant scenario. For a droplet of 1 μm radius, a large fraction of the total OH-benzene reaction (15% for H₂O₂, 20% for nitrate, and 35% for FeOH²⁺) would occur in the surface layer, which accounts for just 0.15% of the droplet volume.     

A synergism between ultraviolet and gamma radiation in producing aerosol particles from SO2H2SO4 laden atmospheres

Experiments were performed to compare the capability of u.v. light, γ-radiation and simultaneous u.v. and γ-radiation to produce aerosol particles in a mixture of SO₂, NO₂ and synthetic air at different humidities. In the presence of u.v. radiation, γ-radiation was found to enhance the particle production at dose rates as low as 10⁻⁴ μGy s⁻¹ at 0% r.h., and 2 × 10⁻² μGy s⁻¹ at 75% r.h. γ-radiation alone did not produce aerosol particles at the same dose rates. The possible processes underlying this synergistic effect are discussed.     

Fe/Ga2O3-Al2O3催化甲烷还原NO的性能

以甲烷为还原剂的选择性催化脱硝技术(SCR-CH_4)是一种很有潜力的新的脱硝方法,但催化剂的催化活性比较低。为了提高催化剂的活性以及抗水能力,可使用Fe对Al_2O_3负载的Ga_2O_3催化剂进行改性。采用共沉淀法,制备了xFe/Ga_2O_3-Al_2O_3催化剂,在固定床反应器中测试其选择性催化CH_4还原NO的性能。使用XRD、N_2吸附脱附、XPS、H_2-TPR、Py-IR等方法进行表征。结果表明:经过Fe改性后的催化剂提高了中高温的催化活性,提高了催化剂的N_2选择性,并改善了催化剂的抗水特性;5Fe/Ga_2O_3-Al_2O_3催化剂在500℃、富氧条件下,达到76%的NO转化率和100%的N_2选择性;在5%水蒸气条件下,5Fe/Ga_2O_3-Al_2O_3在500℃仍保持60%以上的NO转化率。N_2吸附脱附结果显示,引入Fe后,催化剂保持了原有比表面积,并且大大增加了催化剂孔径,可提高催化剂抗水能力。XPS与UV-vis显示,5Fe/Ga_2O_3-Al_2O_3具有高含量的游离态Fe~(3+),可提高催化剂的中高温活性。H2-TPR结果显示,Fe的引入提高了催化剂氧化还原能力,增强了原有Ga_2O_3-Al_2O_3中高温的还原活性。Py-FT-IR结果显示,催化剂表面同时存在Lewis酸和Br?nsted酸,铁的引入增加了催化剂表面的Lewis酸量。因此,Fe修饰Ga_2O_3-Al_2O_3是提高Ga_2O_3-Al_2O_3催化剂的SCR-CH_4脱硝性能的有效方法。     

Continental and global sulfur budgets—I. Anthropogenic SO2 emission

The aim of this study is to determine the atmospheric sulfur budgets of the continents in the absence of any comprehensive published work on this subject to date. In this first part the anthropogenic SO₂ emission inventories of the continents are calculated on the basis of a data survey on the consumption of S-containing fossil fuels, their sulfur contents, the production statistics of SO₂ emitting industrial processes, and the appropriate emission factors. It is found that at present about 2.4 Tg, 4.1 Tg, 0.7 Tg and 18.3 Tg Sy⁻¹ are emitted in the form of SO₂ from Africa, South America, Oceania and Asia, respectively. The greatest increase in the anthropogenic SO₂ emission during the last decade is calculated for Asia.     

Minnesota Power’s Operating Experience with Integrated Particulate and SO2 Scrubbing

Minnesota Power currently has in commercial operation a 500 MW gas cleaning system consisting of a venturi particulate scrubber, integrated with a spray tower SO₂ absorber. The system was designed to achieve 99.7% particulate removal and 90% SO₂ removal based upon burning a 2.8 % sulfur coal.

Initially the concept of using a venturi for wet particulate collection was selected based upon a significant cost saving of $25 million compared to dry particulate collection devices. Subsequently, the Interaction of particulate collection with SO₂ removal provided additional operating cost benefits. Prior to start-up of the commercial system, a pilot plant was used to evaluate various modes of operation. Results showed that alkali contained in the fly ash removed with the venturi was sufficient to meet the alkali requirement for SO₂ removal.

Clay Boswell Station Unit No. 4 was started up during March 1980. Since initial start-up the system has exhibited almost 100% availability. EPA compliance testing has confirmed that the system Is meeting its emission standards. The unit is operating with fly ash as the only source of alkali. Since commercial operation started, no external alkali has been purchased.

This paper will discuss the design details of the system and performance of the commercial system.