Reduced combustion mechanism for C1–C4 hydrocarbons and its application in computational fluid dynamics flare modeling

Emissions from flares constitute unburned hydrocarbons, carbon monoxide (CO), soot, and other partially burned and altered hydrocarbons along with carbon dioxide (CO₂) and water. Soot or visible smoke is of particular concern for flare operators/regulatory agencies. The goal of the study is to develop a computational fluid dynamics (CFD) model capable of predicting flare combustion efficiency (CE) and soot emission. Since detailed combustion mechanisms are too complicated for (CFD) application, a 50-species reduced mechanism, LU 3.0.1, was developed. LU 3.0.1 is capable of handling C₄ hydrocarbons and soot precursor species (C₂H₂, C₂H₄, C₆H₆). The new reduced mechanism LU 3.0.1 was first validated against experimental performance indicators: laminar flame speed, adiabatic flame temperature, and ignition delay. Further, CFD simulations using LU 3.0.1 were run to predict soot emission and CE of air-assisted flare tests conducted in 2010 in Tulsa, Oklahoma, using ANSYS Fluent software. Results of non-premixed probability density function (PDF) model and eddy dissipation concept (EDC) model are discussed. It is also noteworthy that when used in conjunction with the EDC turbulence-chemistry model, LU 3.0.1 can reasonably predict volatile organic compound (VOC) emissions as well.

Implications: A reduced combustion mechanism containing 50 C₁–C₄ species and soot precursors has been developed and validated against experimental data. The combustion mechanism is then employed in the computational fluid dynamics (CFD) of modeling of soot emission and combustion efficiency (CE) of controlled flares for which experimental soot and CE data are available. The validated CFD modeling tools are useful for oil, gas, and chemical industries to comply with U.S. Environmental Protection Agency’s (EPA) mandate to achieve smokeless flaring with a high CE.     

Observation of black carbon aerosol in Beijing,2003

The objective of this study was to determine the black carbon concentration in Beijing in 2003. The aerosol properties were measured using an Aethalometer and a tapered element oscillating microbalance (TEOM) on the roof of the Physics Building of Peking University (39.99° N, 116.31° E) from July to August 2003 and from November 2003 to January 2004. The average black carbon (BC) concentrations in the summer and winter were 8.80 and 11.4 μg/m³, respectively. During winter, two different cyclone cut offs were installed at the inlet of an aethalometer. The BC mass concentration in TSP, PM₁₀, and PM_2.5 were obtained. The results indicated that in winter aerosol, 90% of BC exited in PM₁₀ and 82.6% of BC exited in PM_2.5. The BC in PM₁₀ accounted for 5.11% of the PM₁₀ mass. Translated from Acta Scientiae Circumstantiae, 2005, 25(1): 17–22 [译自: 环境科学学报]     

硫酸生产废水中砷去除方法的研究

对硫酸生产中水洗净化工序排放的废水分别采用灰灰石和鼓风氧化法,铁屑法和铁盐法进行处理试验,结果表明,采用铁盐法级处理工艺处理废废水是可行的,控制组处理的ＰＨ分别为８－１０和８－９,Ｆｅ／Ａｓ摩尔比分别为１和５,当进水Ａｓ含量为１１５ｍｇ／Ｌ时,经两组处理后,出水Ａｓ含量〈０．５ｍｇ／Ｌ,重金属离子,ＰＨ,ＳＳ等指标均符合国家排放标准。     

密切值法用于城市污水处理厂布局规划的研究

用密切值法作多目标决策优选，由城市污水处理厂的3个标准方式和11个家处理厂的工艺改造投资、污水厂运行成本和处理水量等11个评价指标的极端情况，组成“虚拟”的最好（长期保留）和最差（应该废除）方案，进而求出各污水处理厂（统称为样本点）与最好、最差方案的距离，计算可综合反映与最好和最差方案距离两者水平的综合参数－密切值，并根据密切值的大小进行排序。实例计算表明，密切值法与灰色局势决策法得到相似的排序结果，说明密切值法用于城市污水处理厂布局规划是切实可行的。而且密切值法不需要确定白化函数等主观参数，计算结果更客观和可靠。     

Soil CO2 flux in relation to dissolved organic carbon, soil temperature and moisture in a subtropical arable soil of China

IntroductionCarbondioxide(CO2 ) ,concentrationofwhichinatmosphereisincreasingat 0 5%annually ,isthemostimportantgreenhousegascausingglobalwarming(Lal,1 995) .SoilCO2 evolutionfromsoilsisoneoftheimportantsourcesofatmosphericCO2 aswellasamainoutputpathwayofsoilorganiccarbonpool(SOC) (Eswaran ,1 993 ;Batjes,1 996;Mosier,1 998) .ApartfromcontributingCtotheatmosphere ,soilCO2 evolutioncanalsobeusedasanindexofunder groundprocesses,andoftheCcyclingcapacityofsoilecosystems.SoilCO2 evolutionge…     

废水毒性鉴别评价方法

废水毒性鉴别评价是１９８４年发展起来的一项新技术，目的是快速，简便地鉴别引起毒性的化学物质。包括毒物的分离，浓缩，样品分级，仪器分析，毒性追踪，相关性等技术，本方法分三个阶段：毒物特征，毒物鉴别、毒物确证。     

垃圾填埋场渗滤液生物处理尾水的性质研究

采用多种先进测试分析仪器对不同月份的垃圾填埋场渗滤液生物处理尾水(简称渗滤液尾水)进行了全面的分析.结果表明,经生物处理后的渗滤液尾水难以进一步生物降解,仍然有很强的污染性,COD和NH3-N仍分别高达419～622、12.4～174.0 mg/L,未达到国家排放标准,且仍含有多种环境优先控制污染物.除有机物外,渗滤液尾水中还有部分无机类物质贡献COD,TN主要由无机氮构成.渗滤液生物处理的效果与温度关系密切,6、9月的处理效果明显好于3、12月.     

活性污泥系统神经网络建模与仿真研究

采用神经网络技术对松江污水厂污水处理活性污泥系统进行建模试验研究，在对实际运行数据按机理准则和范围准则剔除异常数据后，将样本数据随机分成训练样本、检验样本和测试样本。用试凑法确定合理的神经网络隐层节点数，以避免采用过大或过小的网络结构，在训练过程中用检验样本实时监控从而避免“过训练”现象的影响，较好地解决神经网络方法建模的两大难题，从而建立可靠、有效的活性污泥系统神经网络模型。并应用建立的网络模型对活性污泥系统的运行情况进行了仿真研究。建模研究表明，神经网络技术能较好地应用于活性污泥系统的建模，模型具有较好的泛化能力，有很好的实用价值。