煤粉再燃还原NOx动态过程试验研究

通过固定床对煤粉再燃还原NO_x的微观动态变化过程,以及不同φ(O₂)条件下的再燃脱硝效果进行了试验研究,结果表明,煤粉再燃过程存在典型的3阶段分布特性,分别是再燃煤粉早期NO生成阶段、挥发份的均相还原阶段和焦炭的非均相还原阶段.再燃粉煤早期NO生成阶段和焦炭的非均相还原阶段对φ(O2)变化不敏感,挥发份的均相还原阶段对φ(O₂)变化非常敏感,NO还原效率随φ(O₂)的增加而降低,φ(O₂)=8％是NO还原有效与否的分界线,当φ(O₂)>8％时,再燃煤粉非但不能对来流NO进行有效还原,而且还生成了新的NO.要获得理想的脱硝效果,需要φ(O₂)<5％,对应挥发份化学当量比SRV<0.8. 通过对不同φ(O₂)条件下的NO动态曲线进行定量积分分析,发现挥发份是富燃还原性气氛下还原NO的主要贡献成分,同样在贫燃氧化性气氛下也是NO生成的主要贡献成分.同时还给出了神华煤再燃还原NO的效率与氧量气氛之间的经验公式.     

垃圾焚烧电厂焚烧炉-余热锅炉性能及NOx排放

为了掌握新建机组运行状况,探索烟气再循环对垃圾焚烧电厂污染物排放的影响,针对某垃圾处理量为500 t/d的垃圾焚烧电厂,现场测试省煤器出口烟气成分及炉内烟气温度,试验研究焚烧炉-余热锅炉性能,定量计算焚烧炉-余热锅炉效率及各项热损失,并根据试验测试结果,分析炉内NO_x生成的影响因素. 结果表明：在不同负荷下,机组总热损失中排烟热损失所占比例最大,其次为炉渣热损失,在试验范围内,烟气再循环量对焚烧炉-余热锅炉效率影响较小;烟气中氧气的体积分数及烟气再循环对NO_x排放影响显著,省煤器出口氧气的体积分数由4.52%增加到8.00%,NO_x质量浓度由209.54 mg/m³升高到307.30 mg/m³,增加46.65%;与烟气再循环系统停运相比,当烟气再循环阀门全开时,省煤器出口NO_x质量浓度由209.54 mg/m³降为126.15 mg/m³.     

燃煤锅炉超低排放改造技术实践

介绍了某公司目前*号燃煤锅炉脱硝、除尘、脱硫装置的现状及存在问题,探讨了常用的几种燃煤锅炉超低排放改造路线,比较了各自的优缺点,并结合实际选择超低排放改造的工艺路线,详细阐述了本次超低排放改造的主要内容,收集了改造后的运行情况并进行了分析。由运行数据可知,某公司*号锅炉通过超低排放改造技术实践,达到了燃煤电厂污染物排放最新指标要求。     

某2 027 t/h锅炉变工况掺烧污泥燃烧特性研究

采用Fluent软件,针对某2 027 t/h四角切圆煤粉锅炉不同负荷下单独燃烧煤粉、煤粉和污泥混烧工况进行了数值模拟,研究了炉内流动、燃烧和NOx排放特性。结果表明：模型能够模拟锅炉燃烧过程,模拟误差在10%以内;掺混污泥对炉内速度场影响较小,掺混污泥后,水分蒸发吸热,炉膛整体温度水平下降,中上层燃烧器区域CO和HCN生成量增加,还原性气氛增强,NOx生成受到抑制;掺混10%比例污泥后,600 MW,510 MW,450 MW工况下平均温度峰值分别降低了15.5 K,8.2 K,3.1 K,NOx排放分别降低10.9%,13.1%,8.1%。     

大型电厂锅炉NOx排放特性的支持向量机模型

为了降低大型电厂锅炉NOx的排放,并对燃烧进行优化和控制,应用支持向量机算法建立了大型四角切圆燃烧电站锅炉NOx排放特性模型,利用NOx排放的热态实炉试验数据对模型进行了训练和校验,并对支持向量机算法模型中的参数g和C的选择进行了较深入的探讨,定性地分析了模型参数g和C的变化对模型预测能力的影响,获得了最佳的模型参数.利用该模型对不同实验工况下NOx的排放作出了预测,结果说明采用支持向量机算法建模达到了比较准确的预测效果,与其他建模方法相比具有泛化能力好、计算速度快的优点.     

220 t/h水煤浆锅炉NOx排放特性的研究

为了解水煤浆锅炉NO_x排放规律和降低NO_x的排放,对一台220 t/h水煤浆锅炉进行了一系列实验研究.提出了优化浆温和雾化蒸汽压力、适当降低预热空气温度和优化吹灰次数和时间等优化运行方式来实现水煤浆燃烧的低NO_x排放.结果显示燃料型NO_x是水煤浆燃烧过程中NO_x生成的主要来源,锅炉负荷、过量空气系数、温度、吹灰以及水煤浆特性等都对NO_x的生成有复杂的影响,在不影响燃烧的情况下,低氧量运行有利于降低NO_x排放质量浓度.     

空气分级燃烧降低燃煤电站锅炉NOx生成的技术分析

在燃煤电厂锅炉燃烧中,NOx生成浓度高,排放量大,严重影响大气环境品质.而煤种、一次空气系数、锅炉负荷、火上风投停是影响NOx生成的重要因素,在大型电站燃煤锅炉中实施空气分级燃烧技术,可降低NOx排放的浓度.     

欺骗攻击下一类神经网络的自适应事件触发H∞滤波

本文主要研究了在欺骗攻击下的离散时间神经网络的H_∞滤波器设计问题.考虑到被控系统和滤波器在一个易受外部网络攻击且带宽有限的共享通信网络上进行信息交换,本文提出了自适应事件触发机制来减轻数据传输的通信负担.此外,由于通信网络的开放性和互通互联,通过共享通信网络传输到滤波器的实际输入信息可能会被攻击者注入的虚假信息所改变.在此基础上,利用构造Lyapunov-Krasovskii泛函、线性矩阵不等式等处理技术,本文给出了滤波误差系统渐近稳定的充分条件,并且设计了满足预设性能的H_∞滤波器,最后通过一个仿真实例验证了所提方法的有效性.     

浅析现代燃煤锅炉的节能技术

现代的燃煤锅炉是一个能源消耗很大的设备,如何做好锅炉运行和对能源的节省,本文从锅炉的技术改造,燃料的节约控制和操作工人管理培训等方面探索了燃煤锅炉节能的可能性,为实际生产中燃煤锅炉的节能运作提供参考。     

我校参与的“降低中国燃煤锅炉二氧化碳排放”国际合作项目取得阶段性成果

“降低中国燃煤锅炉二氧化碳排放”项目是中国与加拿大政府间的技术合作项目，由国家商务部和加拿大国际开发署（CIDA）于2003年5月正式签署执行。该项目由加拿大自然资源部能源技术中心全面负责，中方参加单位为西安热工研究院、东北电力科学研究院和华北电力大学。     

水合肼选择性非催化还原烟气中NO_x的反应特性

分析了水合肼在温度为700~1 000℃,氧含量为3.6%~11.4%,NO浓度为450×10-6(体积比)左右时,选择性非催化还原法对烟气中NOx的脱除效果.研究结果表明,用水合肼作为脱硝还原剂时,肼可直接分解产生NH2活性基元,且合适的高温和较低的O2含量有利于NOx的还原脱除.     

煤电机组应对二氧化碳减排的策略

美国环保署要求,新建燃煤电厂的CO_2排放限值为年平均发电碳排放强度不大于635 kg/MWh。其建议的"减排最佳系统"(BSER)技术路线为:对部分烟气量进行碳捕捉、运输和储存(CCS)。由于CCS存在成本、安全性和地质储存条件苛刻等短板,可采用非CCS的煤电机组碳减排策略,即进一步提高超超临界机组的热效率、采用冷热电联供、燃煤耦合生物质发电等3种技术路线。对这些技术路线满足美国碳排放限值的技术现状、前景和条件进行分析后,得出了当前的技术水平下采用冷热电联供或燃煤耦合生物质发电是两个可行且经济的手段,而进一步提高超超临界机组的热效率也具有现实可行性的结论。     

碱金属对Ce/TiO_2催化剂的毒化研究

对Ce/TiO2催化剂的碱金属中毒机理进行了系统性研究.采用浸渍法和溶胶凝胶法进行实验,发现碱金属对催化剂活性有抑制作用,并通过一系列表征分析了导致这一结果的原因.     

生活垃圾焚烧厂SCR低温催化剂运行案例分析

以某生活垃圾焚烧厂实际运行的蜂窝状钒钨钛低温脱硝催化剂为研究对象,通过压损测试、活性测试和脱硝效率检测,研究了典型的选择性催化还原法(SCR)低温催化剂催化活性的影响因素。运行结果表明,蜂窝状催化剂在抗中毒能力上要强于颗粒状催化剂;SCR低温催化剂反应温度可降低到166~170℃,脱硝效率达到50%左右;为控制排烟中的氨逃逸量,氨氮当量比值不宜超过1.3。     

NOx emission characteristics of hydrogen internal combustion engine

In order to investigate the NOxemission of hydrogen internal combustion engines.A test system for four-cylinder intake port-fuel-injection hydrogen internal combustion engine(H2ICE)is established to study the effect of fuel-air equivalence ratio,ignition advance angle,engine speed and exhaust gas recirculation on NOx emission.Experimental results show that the fuel-air equivalence ratio is the key factor to NOxemission,NOxemission concentration is always higher than 8 000×10-6 when the fuel-air equivalence ratio is larger than 0.8and lower than 500×10-6 when the fuel-air equivalence ratio is smaller than 0.5.The ignition advance angle and engine speed also play important roles on NOxemission formation.EGR is an useful method to reduce NOx emission concentration at large fuel-air equivalence ratio especially when engine speed is low and EGR ratio is high.     

超临界燃煤机组烟气脱硝技术的应用比较

重点介绍了目前超临界机组典型的烟气脱硝技术,并进行比较分析.根据我国燃煤电站可持续发展要求和目前国内脱硝技术发展情况,指出了超超临界燃煤电站烟气脱硝装置的选择方向.     

Structural and optical characteristics of Al x Ga1- x N/AlN superlattice

AlN/Al_0.3Ga_0.7N superlattices were grown on (0001) sapphire substrate by metal-organic chemical vapor deposition (MOCVD). The superlattice period varies from 6 to 30. The layer thickness of different period stack was designed. GaN or AlGaN template was employed for growing AlN/AlGaN superlattices. Reflectivity, SEM, AFM and XRD data of the Al _x Ga_1-x N/AlN superlattices are presented. It is found that the templates used have an intensive impact on surface roughness and interfacial properties of following AlN/AlGaN superlattices. The result of atomic force microscopy indicates that AlN/AlGaN superlattices grown on GaN template exhibit quasi-two-dimensional growth mode. The resulting superlattice has a smooth surface morphology and distinct interface. No crack is observed in the area of a 2-inch wafer. Supported by the Special Funds for Major State Basic Research Project (973 Project) (Grant No. 2006CB6049), the Hi-tech Research Project (Grant Nos. 2006AA03A103, 2006AA03A118, and 2006AA03A142), the National Natural Science Foundation of China (Grant No. 60676057), and the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20050284004)     

Performance of an activated carbon made from waste palm shell in simultaneous adsorption of SO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> and NO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> of flue gas at low temperature

This study examined the individual and simultaneous adsorption of SO{in{itx}} (SO{in{it2}}) and NO{in{itx}} (NO-NO{in{it2}}) on activated carbon prepared from waste palm shell. The adsorption process was examined in a fixed bed reactor at low temperatures (100\2-300\dgC). For individual adsorption without any catalytic activation, SO{in{itx}} showed good adsorption whereas NO{in{itx}} was very much poor. In the simultaneous adsorption of SO{in{itx}} and NO{in{itx}}, SO{in{itx}} showed greater adsorption affinity than NO{itx}. For palm shell activated carbon (PSAC) impregnated with metal catalyst (Ni and Ce) the concentration adsorbed profile showed that the amount of SO{in{itx}} adsorbed decreased regularly, while the amount of the adsorbed NO{in{itx}} increased irregularly. The properties of the pure and impregnated PSAC were analyzed by BET, SEM and EDX. These investigations indicated that PSAC impregnated with metal catalyst is the determining factor in the adsorption of SO{in{itx}} and NO{in{itx}} simultaneously. Supported financially by Yayasan FELDA, Malaysia (Grant No. 6050075)     

Synthesis of γ-Al2O3 nanoparticles by chemical precipitation method

Highly pure active γ-Al₂O₃ nanoparticles were synthesized from aluminum nitrate and ammonium carbonate with a little surfactant by chemical precipitation method. The factors affecting the synthesis process were studied. The properties of γ-Al₂O₃ nanoparticles were characterized by DTA, XRD, BET, TEM, laser granularity analysis and impurity content analysis. The results show that the amorphous precursor Al(OH)₃ sols are produced by using 0.1 mol/L Al(NO₃)₃ · 9H₂O and 0.16 mol/L (NH₄)₂CO₃ · H₂O reaction solutions, according to the volume ratio 1.33, adding 0.024% (volume fraction) surfactant PEG600, and reacting at 40 °C, 1 000 r/min stirring rate for 15 min. Then, after stabilizing for 24 h, the precursors were extracted and filtrated by vacuum, washed thoroughly with deionized water and dehydrated ethanol, dried in vacuum at 80°C for 8 h, final calcined at 800 °C for 1 h in the air, and high purity active γ-Al₂O₃ nanoparticles can be prepared with cubic in crystal system, O _H ⁷ -FD3M in space group, about 9 nm in crystal grain size, about 20 nm in particle size and uniform size distribution, 131. 35 m²/g in BET specific surface area, 7 – 11 nm in pore diameter, and not lower than 99.93% in purity. Foundation item: Project(03JJY3015) supported by the Natural Science Foundation of Hunan Province