Mechanism of NO reduction with non-thermal plasma

Non-thermal plasma has been proved to be an effective and competitive technology for removing NO in flue gas since 1970. In this paper, the NO reduction mechanism of the non-thermal plasma reaction in NO/N2/O2 system was investigated using the method of spectral analysis and quantum chemistry. By the establishment of NO reduction and gas discharge plasma emission spectrum measuring system, the NO reduction results, gas discharge emission spectra of NO/N2/O2 and pure N2 were obtained, and then the model of molecular orbit of N2 either in ground state or its excited state was worked out using the method of molecular orbit Ab initio in SelfConsistent Field(SCF). It was found that NO reduction in NO/N2 gas discharge plasma was achieved mainly through a series of fast elementary reactions and the N(E6) at excited state was the base for NO reduction.     

上海市燃油、燃气锅炉NOx排放现状及控制建议研究

简述了上海市燃油、燃气锅炉的区域分布及额定蒸发量分布,结果表明上海市燃油、燃气锅炉以10 t/h以下的小锅炉为主;分析了上海市燃油、燃气锅炉NOx排放浓度水平、超标情况及提标潜势,研究显示燃油锅炉NOx排放浓度水平高于燃气锅炉、NOx超标均出现在10 t/h以下小锅炉、额定蒸发量较高的锅炉NOx排放水平相对较低,较严标准限值的控制下达标率也相对较高;基于以上研究结果,提出了加强NOx监测及推进锅炉低氮燃烧改造工作等控制建议.     

城市生活垃圾与煤流化床混烧过程中氮氧化物排放研究

针对我国城市生活垃圾热值低等特性。在流化装置上进行了城市生活垃圾与煤混燃实验，研究了在混燃过程中城市生活垃圾与煤掺烧比例及床层温度变化对NO和N2O排放浓度的影响。实验结果显示，随掺烧垃圾量逐渐增加时，NO排放浓度降低。而N2O排放浓度先降低然后增加，当城市生活垃圾与煤掺烧比例恒定时，随床温的增加NO排放浓度增加，N2O排放浓度呈下降趋势，采用前向式神经网络，以掺烧比和床温作为输入参数，对NO的排放进行预测。结果显示精度较高。     

污泥与煤混烧NO排放特性研究

利用管式电炉和烟气分析仪进行了沈阳市某市政污泥和铁法烟煤的混烧实验,对比研究了污泥、煤粉、泥煤掺混样品燃烧NO的析出特性,以及粒度、污泥掺混比例对二者混烧NO析出的影响.结果表明,煤粉单独燃烧过程中NO的析出峰为单峰,污泥样品NO析出峰为双峰.燃料粒度的细化可使污泥和煤的NO析出量减少,却增大了掺混样品NO的析出量.因此,对于干污泥与煤掺烧而言,污泥掺混比例建议在10％～20％之间,这样既能保证较好的燃烧特性,又可避免过高的氮转化率.     

人造板甲醛释放影响因素的环境箱试验与模型研究

采用环境箱试验与数学模型模拟人造板中甲醛的释放过程,探讨温度、湿度、封边处理、材质等因素对甲醛释放的影响.环境箱实验表明,随环境温度增加或湿度增加,甲醛初始释放量增高;人造板封边后甲醛释放率明显减小;3种材质的人造板甲醛释放速率依次为中密度板>刨花板>大芯板.经验衰减模型与物质传输模型的对比分析表明,物质传输模型比衰减模型更有利于解释环境箱试验结果.     

Incineration of kitchen waste with high nitrogen in vortexing fluidized-bed incinerator and its NO emission characteristics

Some municipal solid waste (MSW) can be used as the fuel. Combustion of MSW with high nitrogen content is successfully conducted in a lab-scale vortexing fluidized-bed incinerator (VFBI). Pigskin with 16.5 wt.% nitrogen content was used to simulate the high nitrogen content kitchen waste, and silica sand was used as the bed material. The effects of operating conditions, such as the bed temperature, freeboard temperature, excess oxygen ratio, and static bed height on the CO and NO concentrations at the exit of combustor and cyclone were investigated. The experimental results show that the freeboard temperature is the most important factor for CO emission. The order of operating conditions impact on the NO emission is: (1) excess oxygen ratio; (2) bed temperature; (3) freeboard temperature; and (4) static bed height. Utilizing cyclone can significantly reduce the CO emission concentration when the CO concentration released from the freeboard is higher than 50 ppm. On the other hand, the cyclone has no significant effect on the NO emission. Despite having high nitrogen content, a low conversion from fuel-N to NO was attained. Compared with other types of combustors, VFBI reduces the CO and NO emission concentrations much better when burning MSW with high nitrogen content.     

Chance-constrained programming (CCP)abatement of SO_2 emission for acid deposition control in Liuzhou City

A deterministic linear programming model which optimizes the abatement of each SO2 emission source, is extended into a CCP form by introducing equations of probabilistic constrained through the incorporation of uncertainty in the source-receptor-specific transfer coefficients. Based on the calculation of SO2 and sulfate average residence time for Liuzhou City, a sulfur deposition model has been developed and the distribution of transfer coefficients have been found to be approximately log-normal. Sulfur removal minimization of the model shows that the abatement of emission sources in the city is more effective, while control cost optimization provides the lowest cost programmes for source abatement at each allowable deposition limit under varied environmental risk levels. Finally a practicable programme is recommended.     

环境影响评价中停车场CO排放量的计算

现在的建设项目大多建设停车场,其排放的污染物中一氧化碳的浓度最大,但是,鉴于经费制约,实测比较困难.确定排放量最关键的参数为等速工况单车排放因子,本文用五种方法对其进行拟和,并通过结果的比较,认为小型车适用指数法,大中型车适用多项式法(二次),并给出了CO等速工况单车排放因子拟和公式,相关系数均在99%以上.最后给出了停车场CO排放量的计算公式,希望对广大环评工作者有所裨益.     

基于碳减排目标与排放标准约束情景的火电大气污染物减排潜力

从我国"十四五"及2035年远景目标经济发展预测出发,结合碳减排战略目标下的既有与强化政策情景,基于弹性系数法预测电力需求,测算在不同污染物排放标准约束情景下火电大气污染物排放情况及减排潜力,结果表明,在不同的政策和排放标准约束情景下,我国火电行业烟尘、SO2和NOx排放水平变化呈现出不同的趋势,到2035年,在2016年水平上的减排潜力分别在45.97％～85.37％、52.61％～84.90％和33.80％～71.08％之间,来自碳减排目标下政策因素带来的减排潜力,较不同污染物排放标准约束条件带来的减排潜力更为明显,在强化政策情景下,采取保持模式标准约束的污染物减排潜力已与超低模式基本相当,甚至超过或接近既有政策下采取收严模式标准约束的效果,通过强化实施能源和电力优化政策,加快实现火电发电量达峰,合理引导高污染排放水平火电机组优先退出生产,同样可使火电大气污染物排放得到有效控制,还可避免环保改造投资的浪费和损失.     

Urban NO2 concentrations in the U.K. in 1987

A mational air quality monitoring network has been established in the U.K. by Warren Spring Laboratory, on behalf of the U.K. Department of the Environment, to determine compliance with the European Community Directive for nitrogen dioxide. Data from the six network sites for 1987 are presented and analysed.No site in the U.K. breached the NO₂ Directive Limit Value during this year, though the closest approaches were at the two London stations. Annual average NO₂ concentrations, which varied from 23 to 39 ppb, were consistent with the top five percentile of long-term measurements from a national survey of over 360 U.K. urban areas carried out in 1986.The temporal variability of NO₂ concentrations was substantially lower over all time scales than that for NO: winter/summer ratios for all sites averaged 2.9 for NO and 1.3 for NO₂. Most sites showed strong diurnal variations for NO which were primarily influenced by traffic emissions during rush hours, although these variations were less marked for NO₂.A markedly non-proportional relationship between annual and daily average NO₂ and NO_x levels was observed, and this has important implications for its efficacy of possible NO_x emission control strategies. An analysis of measured NO₂/NO_x ratios over weekends and weekday periods demonstrates, for instance, that a 20% emission cutback may result, typically, in a corresponding NO₂ reduction of 12% at urban locations in the U.K. NO_x reductions, however, exert a more proportional effect on NO₂ concentrations at kerbside and rural locations.     

港口罢工对周边空气质量的影响

港口污染物的排放浓度极大地影响着周边的空气质量,以2013年3月28日香港国际集装箱码头发生的罢工事件为契机来探究港口运作短暂的瘫痪对周边空气质量的影响。首先,进行污染物之间的相关性分析确定影响本次罢工事件的污染物主要为NO_2、NO_x、SO_2以及O_3。其次,基于罢工前、罢工期间以及罢工后污染物排放的浓度变化,进行横向对比发现罢工期间的污染物确实有一定程度的减少。再次,利用纵向对比排除四季带来的影响探究不同年份同一阶段污染物浓度的变化情况评估罢工期间的空气质量。最后,以NO_2为例建立预测模型对罢工期间的NO_2浓度进行预测,根据实际值与预测值之间的差异来说明罢工影响了NO_2的预测趋势。这项研究主要强调港口空气质量对整个环境的影响,在一定程度上说明政府实施政策的有效性,为政府提供了决策支持,同时也要注重污染物之间的相互转化作用对环境的影响。     

循环流化床二段燃烧燃煤过程中NO和N2O生成与控制研究

在小型石英循环流化床燃煤装置上,进行NO和N₂O生成与控制研究?研究结果表明:随着二次空气率的提高,NO明显下降,二次风口的位置高,NO的下降速率明显一些;随着二次空气率的提高,N₂O开始升高,但升高到一定程度后,随着二次空气率的提高,反而开始下降?此外,二次风口的位置高,N₂O随二次风变化曲线的上升段和下降段的斜率都略大?      

Numerical model to quantify biogenic volatile organic compound emissions: The Pearl River Delta region as a case study

This article compiles the actual knowledge of the biogenic volatile organic compound (BVOC) emissions estimated using model methods in the Pearl River Delta (PRD) region, one of the most developed regions in China. The developed history of BVOC emission models is presented briefly and three typical emission models are introduced and compared. The results from local studies related to BVOC emissions have been summarized. Based on this analysis, it is recommended that local researchers conduct BVOC emission studies systematically, from the assessment of model inputs, to compiling regional emission inventories to quantifying the uncertainties and evaluating the model results. Beyond that, more basic researches should be conducted in the future to close the gaps in knowledge on BVOC emission mechanisms, to develop the emission models and to refine the inventory results. This paper can provide a perspective on these aspects in the broad field of research associated with BVOC emissions in the PRD region.     

基于技术的水泥工业大气颗粒物排放清单

针对我国水泥工业的生产技术及生产过程中的大气颗粒物排放控制技术分类,建立了一个基于技术、自下而上的大气颗粒物排放模型.通过分析我国水泥工业不同生产工艺所占比重的历史变化趋势,以及不同时期水泥工业大气颗粒物控制标准的影响,利用此模型计算了1990-2004年全国水泥工业大气颗粒物的排放系数和排放量.我国水泥工业的大气颗粒物的排放系数由1990年的27.9 kg·t-1水泥下降至2004年的8.05 kg·t-1水泥;大气颗粒物排放量自1990年起逐年增加,于1997年达到最高值l 044×104t,其中PM10排放量为716 X 104 t,PM2 5排放量为436×104t;此后逐年降低,到2001年后又有缓慢增加.我国水泥工业大气颗粒物排放量的地理分布很不均衡,山东、广东、河北、江苏、浙江和河南的排放量超过了全国总排放量的50%.新型干法水泥生产线替代立窑生产线的进程以及2004年<水泥工业大气污染物排放标准>的颁布将很可能大幅降低我国水泥工业的大气颗粒物排放量,从而在很大程度上影响我国的大气颗粒物污染特征.     

氮氧化物在闽南地区酸雨中的贡献

通过对闽南地区降水?雾水和空气质量等数据的分析,说明闽南地区酸雨是燃煤和光化学烟雾混合型污染;闽南地区降水的SO2-₄/NO-₃比值是我国主要酸雨区中最低的,NO_x是闽南地区酸沉降形成的重要致酸前体物之一;闽南地区酸沉降中的NO-₃主要来源于当地的源排放。      

Uncertainty analysis of emission estimates in the RAINS integrated assessment model

Uncertainty is a critical issue for all models that attempt to quantify the necessary emission reductions that are required to meet environmental quality targets. This paper discusses a methodology specifically developed to analyse the uncertainties in the emission estimates with the regional air pollution information and simulation (RAINS) integrated assessment model, considering the uncertainties in the model parameters themselves. Overall, it was found that a typical range of uncertainties for modeled national emissions of sulfur dioxide, nitrogen oxides and ammonia in Europe lies between 10 and 30%. In general, the uncertainties are strongly dependent on the potential for error compensation. This compensation potential is larger (and uncertainties are smaller) if calculated emissions are composed of a larger number of equal-sized source categories, where the errors in input parameters are not correlated with each other. Thus, estimates of the national total emissions are generally more certain than estimates of sectoral emissions. A sensitivity analysis with respect to the uncertainty in input parameters showed that the actual uncertainties are critically influenced by the specific situation (pollutant, year, country). However, the emission factor is an important contributor to the uncertainty in estimates of historical emissions, while uncertainty in the activity data dominates the future estimates.     

Review on the NO removal from flue gas by oxidation methods

Due to the increasingly strict emission standards of NOx on various industries, many traditional flue gas treatment methods have been gradually improved. Except for selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) methods to remove NOx from flue gas, theoxidation method is paying more attention to NOx removal now because of the potential to simultaneously remove multiple pollutants from flue gas. This paper summarizes the efficiency, reaction conditions, effect factors, and reaction mechanism of NO oxidation from the aspects of liquid-phase oxidation, gas-phase oxidation, plasma technology, and catalytic oxidation. The effects of free radicals and active components of catalysts on NO oxidation and the combination of various oxidation methods are discussed in detail. The advantages and disadvantages of different oxidation methods are summarized, and the suggestions for future research on NO oxidation are put forward at the end. The review on the NO removal by oxidation methods can provide new ideas for future studies on the NO removal from flue gas.     

四维通量法施工扬尘排放模型的建立与应用

建立了一种与美国环保局推荐的暴露高度浓度剖面法类似、应用实测数据计算施工扬尘排放量的数学模型——四维通量法模型,以及一套与该模型相匹配的施工扬尘排放量监测方案.采用四维通量法计算施工扬尘排放量,更加简洁方便,并且可以较好地消除偶然因素对计算结果的干扰.将北京城近郊区40多个建筑工地的实测数据代入该数学模型所得到的北京市施工扬尘中TSP排放因子为0.492 kg/(m²·30 d),在数值上是美国环保局AP-42文件推荐排放因子的1.83倍.建议采用本研究得出的本地化排放因子来建立北京市施工扬尘排放清单.     

Emissions of SO2, NO and N2O in a circulating fluidized bed combustor during co-firing coal and biomass

This paper presents the experimental investigations of the emissions of SO2, NO and N2O in a bench scale circulating fluidized bed combustor for coal combustion and co-firing coal and biomass. The thermal capacity of the combustor is 30 kW. The setup is electrically heated during startup. The influence of the excess air, the degree of the air staging, the biomass share and the feeding position of the fuels on the emissions of SO2, NO and N2O were studied. The results showed that an increase in the biomass shares resulted in an increase of the CO concentration in the flue gas, probably due to the high volatile content of the biomass. In co-firing, the emission of SO2 increased with increasing biomass share slightly, however, non-linear increase relationship between SO2 emission and fuel sulfur content was observed. Air staging significantly decreased the NO emission without raising the SO2 level. Although the change of the fuel feeding position from riser to downer resulted in a decrease in the NO emission level, no obvious change was observed for the SO2 level. Taking the coal feeding position R as a reference, the relative NO emission could significantly decrease during co-firing coal and biomass when feeding fuel at position D and keeping the first stage stoichiometry greater than 0.95. The possible mechanisms of the sulfur and nitrogen chemistry at these conditions were discussed and the ways of simultaneous reduction of SO2, NO and N2O were proposed.     

应用模式计算机动车排放因子

以澳门地区机动车污染物排放因子计算为例,介绍了根据当地实际情况,进行模式参数修正,并采用修正的模式确定排放因子的基本方法。结果表明,采用修正模式计算的方法能够比较方便地确定不同时空研究范围内机动车的排放因子。澳门地区机动车的排放水平较高,需要采取更先进的技术以控制机动车的污染。