非均匀入口条件下SCR脱硝系统精准喷氨策略

采用数值计算的方法,根据全尺度数值模拟计算结果和实际测量数据获得符合工程实际情况的SCR非均匀入口边界条件,模拟了整个SCR系统的烟气流动过程.根据喷氨格栅处速度场和浓度场获取NO通量,以此为基准精确分配各喷管喷氨量.研究了不同喷口布置的氨气与NO的对流扩散混合特性,分析了喷氨格栅中喷口密度N、开孔率φ、喷口角度α三个结构参数对SCR反应器内氨氮混合质量、氨氮比分布均匀性的影响.结果表明:增大喷口密度N可以有效地优化氨氮混合效果.当N15.34个/m~2时,增加N对氨氮混合效果的影响不再显著;混合指数β随着喷口开孔率φ的增大会出现先减小后增大的趋势;改变喷口角度α可以改善氨氮混合效果,喷口垂直布置时氨氮混合效果最佳.     

300MW燃煤锅炉SNCR过程的数值模拟

利用FLUENT软件对300 MW燃煤锅炉的选择性非催化还原(SNCR)过程进行了模拟.重点分析尿素溶液的喷射位置、液滴喷射速度、雾化平均粒径对SNCR过程脱硝效率以及漏氨量的影响,从而得到实际运行过程中最佳运行条件.结果显示,增加喷射速度能加快蒸发过程;雾化粒径越大越有利于还原剂的平均分布,但也会延长蒸发时间;在第1,2层同时喷射尿素溶液,并控制雾化平均粒径为0.3 mm和液滴喷射速度为30 m/s时,能够获得较好的脱硝效果.将不同氨氮摩尔比模拟结果与实际过程进行对比,结果表明两者能够较好地吻合.     

燃煤电站锅炉脱硝技术的运用探究

为了解决煤炭污染问题,该文以煤炭电站锅炉污染作为主要研究内容,利用喷氨系统、稀释混合计量系统、氨水储蓄供应系统、卸车系统,构建脱硝系统,探究锅炉脱硝效率受氨水浓度、氨氮比影响,并分析NOX受过剩氧量影响。实验结果表明,降低负荷,控制氨水浓度在3.8%左右,增加氨氮比,降低氧气浓度,有助于燃煤电站锅炉脱硝效率的提升。     

液-液循环流化床制取流体冰雾化机理实验

对液-液系统射流雾化机理进行了实验研究.通过改变水的喷射速度和非相溶介质的流速,来研究不同条件对雾化的影响,利用高速摄像仪捕捉各种工况下的雾化结果.采用图像处理与数值计算相结合的方法对雾化结果进行了统计整理,对雾化过程中影响雾化液滴平均粒径、射锥高度以及雾化现象的关键因素进行了探讨,并应用Rosin-Rammler分布函数对液滴粒径分布进行了分析.结果表明:每种工况下的雾化液滴粒径存在着离散性,能很好地符合Rosin-Rammler分布规律;当非相溶介质流速保持不变时,雾化液滴统计平均粒径与射锥高度分别在喷射速度为2.3与 3.5m/s时,达到最大值;而在相同的喷射速度下,改变非相溶介质流速所得雾化结果也完全不同.喷射速度以及周围非相溶介质的流速是影响雾化结果的重要因素,合理选择其值对优化雾化性能及控制雾化过程有着重要的意义.     

金属矿山气-水喷头雾化特性及降尘能力实验研究

为分析金属矿山多中段高溜井喷头雾化特性及其降尘效果,建立高溜井喷雾降尘实验平台。采用激光粒径分析仪及喷雾实验设备对新型气-水喷头雾化特性、冲击气流对喷雾捕尘能力影响规律进行研究分析。研究结果表明:气、水流量比是影响新型气-水喷头雾化效果的关键因素;当喷头工作时气、水流量比为100～150时,雾化效果最佳,最佳气压和水压区间分别为[0.4, 0.6] MPa和[0.3, 0.5] MPa,雾滴粒径分布在15～35μm范围内;在最佳气压和水压区间内,雾化角度随气压的增加而增大,随水压先增大后减小,最大雾化角度为40°,调整气压是优化雾化角度的主要手段;溜井卸矿冲击气流对喷雾雾滴粒径影响较大,喷雾捕尘能力与冲击气流速度呈负相关。     

等离子体氧化NO耦合湿式氨法同时脱硫脱硝试验研究

为提高燃煤烟气同时脱硫脱硝工艺中的脱硝效率,将等离子体氧化技术应用到湿式氨法脱硫工艺中,建立了等离子体氧化NO耦合湿式氨法的脱硫脱硝试验装置.考察了液气比、氨水浓度、烟气流量、烟气温度、NO初始浓度、SO2初始浓度等工艺参数对同时脱硫脱硝性能的影响.试验结果表明:提高液气比、增加氨水浓度、减少烟气流量、降低烟气温度、减小NO和SO2初始浓度都可以提高脱硝效率,而试验范围内工艺参数对脱硫效率的影响几乎可以忽略;当液气比为10 L/m3、氨水浓度为4 mol/L、烟气流量为10 m3/h、烟气温度为85℃、NO初始浓度为3.5×10-4、SO2初始浓度为1.0×10-3时,该试验装置的脱硫效率和脱硝效率分别为99.6%和69.4%.     

基于氨逃逸的SCR系统喷氨优化设计

随着经济不断发展,国家对环境的保护政策要求逐年提高,有些省市甚至把氨逃逸浓度作为考核条款,因此对脱硝系统进行优化调整越发重要。选择性催化还原法(SCR)的烟气脱硝技术具有高脱硝率、低氨气逃逸率的特点,已成为应用最广的技术。该文根据SCR的脱硝反应原理,分析出影响脱硝的因素,为脱硝反应器内喷氨的优化调整提供对策,从而有效地减少氨气的逃逸率。     

氨水预处理玉米秸秆糖化工艺条件优化

采用氨水预处理的单因素与正交试验,研究氨水浓度、时间、温度、基质浓度和粒径对玉米秸秆糖化预处理的影响.结果表明:影响氨预处理玉米秸秆的还原糖得率的主要因素是粒径,而影响木质素去除率的主要因素是氨水浓度、浸泡时间和浸泡温度,其最优工艺条件为氨水浓度15％,时间39 h,温度40℃,基质浓度162.5 g·L-1,粒径0....     

溶剂超临界CO2雾化萃取法制备乙基纤维素微粒的研究

通过溶剂超临界CO2雾化萃取法制得了乙基纤维素微粒．研究了溶液喷口流速、溶液浓度、温度、压力对颗粒粒径及其粒径分布的影响．结果表明，改变工艺参数，可在较大范围内调控微粒大小，所得微粒平均粒径为0．64～10．83μm．随着温度和溶液浓度的增加，颗粒粒径及其粒径分布增加；随着压力和溶液喷口流速的增加，颗粒粒径及其粒径分布减小．     

流化床中下喷射流穿射深度研究

对气固流化床中气体下喷射流穿射深度进行了实验及理论探讨，利用湍动射流理论和流体力学理论,给出了床中射流深度的表达式,其结果与实验数据相比较拟合较好。同时还讨论了喷口直径，喷射斜角，颗粒性质对射深的影响。实验用空气—FCC体系和空气一硅胶体系，喷口气速为15m/s～90m/s，喷口直径为5mm和8mm。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that