控制燃油锅炉运行中NOx 生成的技术研究

分析燃油锅炉运行中NOx产生的机理，探讨影响其生成的因素，研究抑制其生成和排放的燃烧技术：低氧燃烧、掺水燃烧、空气分级燃烧和废气循环燃烧等。结合实验研究结果，重点分析空气分级燃烧和废气循环燃烧对油燃烧中燃料氮转化和氮氧化物生成的影响，并介绍一种新型低氮氧化物排放的燃油技术——预蒸发燃烧技术。     

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.     

燃尽风位置高度对NO_x生成的影响

针对山东某电厂200 MW四角切圆燃烧锅炉NO_x排放量过高的问题,采用多空气分级低氮燃烧技术对其进行改造,基于FLUENT软件平台,对改造前后炉内燃烧过程进行模拟计算,与工业性实验结果进行对比分析;并在额定工况下,对5种不同燃尽风位置高度的改造方案进行模拟计算,综合分析炉内燃烧及氮氧化物生成排放的情况,确定燃尽风位置的最佳高度。计算结果表明:改造后,炉内NO_x排放量较改造前降幅40%左右,同时,合理地增加燃尽风位置高度,可进一步降低NO_x的排放量,综合炉内各参数变化的比较得出:燃料从主燃区至燃尽区的最佳运行时间约为0.66 s。     

钢铁行业氮氧化物控制技术及对策

根据2007年第一次全国污染源普查数据,钢铁行业氮氧化物排放量已达81.74万t,约占全国总排放量的4.55％,是继火力发电、机动车、水泥工业后第四大氮氧化物排放源.针对中国重要氮氧化物来源——钢铁工业的氮氧化物生成机制,排放节点及特征,国内外控制技术现状开展综述研究.研究表明,钢铁工业中的氮氧化物的产生以高温型为主.烧结、焦化、炼铁、炼钢、轧钢等过程为主要的氮氧化物排放源.收集并整理了国外在钢铁各工序上的主要氮氧化物控制技术及其在国内的应用状况.在回顾中国钢铁大气污染物控制历程的基础上,提出了中国钢铁行业氮氧化物控制的对策建议.     

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。     

切圆燃烧煤粉炉的空气分级燃烧改造

阐述了分级燃烧抑制NOx形成的基本原理,介绍了切圆燃烧煤粉炉的空气分级燃烧改造的基本特点,考察了轴向和径向空气分级、炉内空气浓度等因素对NOx排放量的影响;控制适当条件,使脱氮效率达到30％－50％,对煤粉炉的空气分级燃烧改造进行了费用效益分析。     

国外氮氧化物污染控制的概况

氮氧化物(NOx)废气的排放来自固定源(包括各种燃烧装置)和移动源(内燃机车)两个方面。据美国环境保护局(EPA)估计。99％NOx是从燃料燃烧排放的,其中固定源与移动源各占一半。予期到1985年由于燃煤要增加,因此,固定源与移动源所占比例,将成为70％与30％之比。     

城市下水污泥焚烧过程中二次污染物排放特性的试验研究

在0.15 MWt循环流化床燃烧试验台上进行了城市下水污泥与煤的混烧试验,分析了烟气中的二次污染物排放特性.分析结果表明,利用循环流化床焚烧城市下水污泥时,添加辅助燃料(如煤)及改变焚烧条件,不仅可以达到稳定燃烧的目的,而且有利于抑制焚烧中二次污染物(如CO及二恶英等有机污染物)的生成.分析了焚烧污泥污染物的排放特性,为采用焚烧方式处理城市下水污泥提供了基础性试验数据.     

二甲醚燃烧的甲醛生成特性实验研究

针对二甲醚平面预混火焰,实验研究了燃料当量比和燃料流量对燃烧过程中甲醛产生和排放特性的影响.实验结果表明,甲醛是二甲醚燃烧过程一个重要的中间产物,在火焰面中大量生成,但其中大部分甲醛迅速被氧化消耗;二甲醚燃烧过程中甲醛的生成受燃料当量比和火焰温度影响明显,欠氧(燃料当量比φ＜1)预混合燃烧的甲醛生成显著高于富氧(φ＜1)燃烧;燃料当量比一定时,随着燃料流量增加,火焰中的甲醛浓度升高.     

循环流化床锅炉燃烧城市生活垃圾的研究进展

城市生活垃圾(MSW)产量的与日俱增及环保要求的不断提高,使循环流化床(CFB)燃烧技术逐渐在MSW的回收和利用方面扮演越来越重要的角色.简要分析了国内外采用分类回收及综合利用、卫生填埋、堆肥和一般焚烧方法处理MSW的不足之处以及采用CFB燃烧技术的优越性,重点介绍了国内外采用CFB燃烧装置焚烧MSW的研究和应用现状,指出了目前存在的问题及努力的方向.采用CFB燃烧装置焚烧MSW关于SO2、NOx、CO排放的实验研究和运行结果令人满意,但对HCl、二恶英及重金属排放还需要进一步研究.试验及实际运行结果都表明,采用CFB燃烧装置对MSW进行焚烧处理是切实可行的,它将是未来解决MSW问题的重要手段.     

Estimation of uncertainty of sampling for analysis of pesticide residues

Abstract

A computer model was used to take random samples from primary sample populations obtained from field trials to simulate the uncertainty of sampling for residue analysis of plant commodities and soil. The results indicate about 40%, 30% and 20% relative uncertainty when random samples of size 5, 10 and 25 are taken respectively, from a single lot. Therefore the sample size should be the same for establishing and enforcing legal limits.     

次氯酸钠发生器的研制

介绍了电解法生产次氯酸钠的原理 ,并在原有生产工艺的基础上进行了重新设计和对设备的重新选择、改造 ,得出了各个工艺参数的最佳值 ,生产出高品质的次氯酸钠     

不同泥源对厌氧氨氧化反应器启动的影响

采用2套上流式生物膜反应器,分别接种少量厌氧氨氧化污泥和大量硝化污泥,考察其对厌氧氨氧化反应器启动的影响。污泥接种入反应器后,测得接种厌氧氨氧化污泥的反应器(R1)内MLSS为0.22 g/L,另一个反应器(R2)MLSS为2.7 g/L。与直接接种厌氧氨氧化污泥相比,R1经过72 d的运行才显现出厌氧氨氧化特性。经过114 d的培养,前者氮去除速率由0.23 kg/(m3.d)提升到5.29 kg/(m3.d),总氮去除率大于89%;R2的氮去除速率由0.01 kg/(m3.d)提升到1.1 kg/(m3.d),总氮去除率大于84.6%。说明普通污泥启动需要一个较长的筛选过程,直接接种少量的厌氧氨氧化污泥比接种普通的污泥能够更快启动厌氧氨氧化反应器。     

An application of the theory of kinematics of mixing to the study of tropospheric dispersion

The most common technique used for numerical simulations of tracer mixing is that of the numerical solution of the advection–diffusion equation with the unresolved fluxes parameterized using the similarity theory. Despite correct predictions of the overall directions of transport, models based on a numerical solution of the advection–diffusion equation lack sufficient accuracy to correctly reproduce the coupling of mixing with small scale processes which are sensitive to the microstructure of the tracer distribution. The objective of this paper is to revisit the basic formalism employed in numerical models used to investigate atmospheric tracers. The main mathematical method proposed here is the theory of kinematics of mixing which could be applied effectively for simulations of atmospheric transport processes. At the beginning of the paper, we introduce simple mathematical transformations in order to demonstrate how complex topological structures are created by mixing processes. These idealistic flow systems are essential to explain transport properties of much more complex three-dimensional geophysical flows. An example of the application of the kinematics of mixing to the analysis of tracer transport on a planetary scale is presented in the following sections. The complex filamentary structures simulated in the numerical experiment are evaluated using some commonly applied statistical measures in order to compare the results with the data published in the literature. The results of the experiment are also analysed with the help of simple conceptual models of fluid filaments. The microstructure of the tracer distribution introduced in the paper is essential to increase our understanding of atmospheric transport and to develop more realistic parameterizations of small-scale mixing. The presented results could also be used to improve calculations of the coupling between microphysical processes and tracer mixing.     

造纸废水混凝处理中SFT助凝替代性研究

中小造纸厂废水处理常用PAC作混凝剂 ,PAM作助凝剂。由于PAM成本很高 ,影响了处理设备的投运率。用超细滑石粉 (SFT)替代PAM助凝 ,与混凝剂PAC配合 ,其混凝处理效果基本相当 ,但是处理成本降低 0 .10元 /m3 。由于SFT属环境无害材料 ,不会给排泥带来二次污染     

红土吸附砷对其动电电位的影响

研究了遵义红土吸附砷对其动电电位的影响 ,从砷酸根浓度和体系pH对红土动电电位影响的角度作了探讨 ,结果表明 ,砷酸根离子浓度越大 ,Zata电位下降幅度越大 ,Zata电位也越低 ;随着体系pH的升高 ,氧化铁胶体动电电位逐渐下降 ,甚至改变了表面电位的符号。由此得出了红土吸附砷属于专性吸附的结论。     

活性炭三维电极法对印染废水的处理研究

对三维电极方法处理印染废水进行了实验研究,初步探讨了活性炭三维电极法处理印染废水的机理,对影响处理效果的各种要素,如反应时间、槽电压和pH值等进行了条件实验,得出了活性炭三维电极法处理印染废水的最佳运行条件为:停留时间120-180 min,槽电压25～30 V,进水pH值6.5～7.5。结果表明,该反应器能有效地降低废水色度,有较高的COD去除效率,并能提高印染废水的可生化性。     

生物质快速热裂解主要参数对生物油产率的影响

以松木木屑为原料,在自制的小型流化床上,开展了生物质热裂解温度、生物质粒径和进料速率对生物油产率的影响实验研究.结果表明,在热裂解温度分别为450、475、500、525和550℃条件下,当热裂解温度为500℃时,生物油产率最高,平均产率达到53.33%(质量百分比).反应温度越高,炭产量越低,不可冷凝气体产量越高,气体发热值越高;粒径＜1 mm的生物质其粒径对生物油产率影响不大;生物质进料速率增加时,生物油产率增加.本研究为生物能的利用提供了新的途径.     

Evaluation of the presence of drugs of abuse in tap waters

A total of seventy samples of drinking water were tested for non-controlled and illicit drugs. Of these, 43 were from Spanish cities, 15 from seven other European countries, three from Japan and nine from seven different Latin American countries. The most frequently detected compounds were caffeine, nicotine, cotinine, cocaine and its metabolite benzoylecgonine, methadone and its metabolite EDDP. The mean concentrations of non-controlled drugs were: for caffeine 50 and 19 ng L⁻¹, in Spanish and worldwide drinking water respectively and for nicotine 13 and 19 ng L⁻¹. Illicit drugs were sparsely present and usually at ultratrace level (<1 ng L⁻¹). For example, cocaine has mean values of 0.4 (Spain) and 0.3 ng L⁻¹ (worldwide), whereas for benzoylecgonine, these mean values were 0.4 and 1.8 ng L⁻¹, respectively. Higher concentrations of benzoylecgonine were found in Latin American samples (up to 15 ng L⁻¹). No opiates were identified in any sample but the presence of methadone and EDDP was frequently detected. Total mean values for EDDP were 0.4 ng L⁻¹ (Spain) and 0.3 ng L⁻¹ (worldwide). Very few samples tested positive for amphetamines, in line with the reactivity of chlorine with these compounds. No cannabinoids, LSD, ketamine, fentanyl and PCP were detected.     

Visualisation of the complexity of EUSES

The interdependencies of parameters applied in the models of EUSES are visualised in a directed connectivity graph. The parameters (inputs, defaults, state variables, outputs) are represented by boxes (nodes) and their relations by lines (edges). The visualisation, on the one hand, clarifies the complexity of the models in EUSES and, on the other hand, creates an overview and transparency. The parameters’ relations to each other can be recognised faster, and the models can be better understood. The complexity was quantified by the number (variety), kind (substance parameter, physico-chemical parameter, concentration, other parameters), and depth (dimension) of the parameter and the number of relations (connectivity). The variety of EUSES (without the modelsSimple Treat andSimple Box whose interior structure is not documented and without the effect and risk characterisation) amounts to 466, the connectivity to 961, and the maximal dimension is 21.