Novel mechanism for the modification of Al_2O_3-based inclusions in ultra-low carbon Al-killed steel considering the effects of magnesium and calcium

Many researchers have explored the inclusion modification mechanism to improve non-metallic inclusion modifications in steelmaking. In this study, two types of industrial trials on inclusion modifications in liquid steel were conducted using ultra-low-carbon Al-killed steel with different Mg and Ca contents to verify the effects of Ca and Mg contents on the modification mechanism of Al_2O_3-based inclusions during secondary refining. The results showed that Al_2O_3-based inclusions can be modified into liquid calcium aluminate or a multi-component inclusion with the addition of a suitable amount of Ca. In addition, [Mg] in liquid steel can further reduce CaO in liquid calcium aluminate to drive its evolution into CaO–MgO–Al_2O_3 multi-component inclusions. Thermodynamic analysis confirmed that the reaction between [Mg] and CaO in liquid calcium aluminate occurs when the MgO content of liquid calcium aluminate is less than 3 wt% and the temperature is higher than 1843 K.

Field emission properties of a-C and a-C：H films deposited on silicon surfaces modified with nickel nanoparticles

The a-C and a-C：H films are deposited on silicon surfaces modified with and without nickel nanoparticles by using mid-frequency magnetron sputtering. The microstructures and morphologies of the films are analyzed by Raman spec- troscopy and atomic force microscopy. Field emission behaviors of the deposited films with and without nickel nanopar- ticles modification are comparatively investigated. It is found that the hydrogen-free carbon film exhibits a high field emission current density and low turn-on electric field compared with the hydrogenated carbon film. Nickel modifying could increase the current density, whereas it has no significant effect on the turn-on electric field. The mechanism of field electron emission of a sample is discussed from the surface morphologies of the films and nickel nanoparticle roles in the interface between film and substrate.

Angle Scattering Method for Soot Concentration Measurement under Ultra-Low Emissions Condition

Aiming at the problem of soot concentration measurement under ultra-low emission conditions,a forward small angle soot concentration measurement method is proposed.Taking a typical boiler emission of 0.1μm-3.0μm bimodal distribution soot as an object,the particle scatter simulation calculation under different parameters is carried out,and the influence of detection angle and particle size on the angular scatteringmeasurement of ultra-low emission soot is analyzed.The influence of detection angle and particle size on the angular scatteringmeasurement of ultra-lowemission soot is analyzed.Preferably,thewavelength of incident light is 650 nm,and the forward detection angle parameter is 15◦for the design of forward small angle soot concentration measurement system.An experimental system for measuring soot with standard concentration is built.Experiments of particle concentration measurement of 1.0μm and 3.0μm under ultra-low emission conditions are carried out.The results show that the average deviation of soot concentration measurement is less than 0.10 mg/m3 under the condition of ultra-low emission by using 15◦of forward detection,which provides an effective way for monitoring ultra-low emission soot concentration in coal-fired power plants.

Re-understanding and Thinking about Environmental Impact of Coal-fired Power Plants under Ultra-low Emission

From the perspective of development background,concepts and related policies of ultra-low emission,according to work practice,some issues and difficulties that need to be paid attention to in the environmental impact assessment of ultra-low-emission thermal power projects were discussed from the aspects of evaluation criteria,evaluation grade and scope,pollution control technical lines,environmental benefit accounting,and total emission control,and corresponding recommendations were put forward.

Distribution and bioavailability of mercury in size-fractioned atmospheric particles around an ultra-low emission power plant in Southwest China

Ultra-low emission(ULE)technology retrofits significantly impact the particulate-bound mercury(Hg)emissions from coal-fired power plants(CFPPs);however,the distribution and bioavailability of Hg in size-fractioned particulate matter(PM)around the ULE-retrofitted CF-PPs are less understood.Here,total Hg and its chemical speciation in TSP(total suspended particles),PM_(10)(aerodynamic particle diameter≤10μm)and PM_(2.5)(aerodynamic particle diameter≤2.5μm)around a ULE-retrofitted CFPP in Guizhou Province were quantified.Atmospheric PM_(2.5)concentration was higher around this ULE-retrofitted CFPP than that in the intra-regional urban cities,and it had higher mass Hg concentration than other sizefractioned PM.Total Hg concentrations in PM had multifarious sources including CFPP,vehicle exhaust and biomass combustion,while they were significantly higher in autumn and winter than those in other seasons(P<0.05).Regardless of particulate size,atmospheric PM-bound Hg had lower residual fractions(<21%)while higher HCl-soluble fractions(>40%).Mass concentrations of exchangeable,HCl-soluble,elemental,and residual Hg in PM_(2.5)were higher than those in other size-fractioned PM,and were markedly elevated in autumn and winter(P<0.05).In PM_(2.5),HCl-soluble Hg presented a significantly positive relationship with elemental Hg(P<0.05),while residual Hg showed the significantly positive relationships with HCl-soluble Hg and elemental Hg(P<0.01).Overall,these results suggested that atmospheric PM-bound Hg around the ULE-retrofitted CFPP tends to accumulate in finer PM,and has higher bioavailable fractions,while has potential transformation between chemical speciation.

Stimulated electromagnetic emissions spectrum observed during an X-mode heating experiment at the European Incoherent Scatter Scientific Association

An extraordinary(X-mode)electromagnetic wave,injected into the ionosphere by the ground-based heating facility at Tromsφ,Norway,was utilized to modify the ionosphere on November 6,2017.The high-power high-frequency transmitter facility located at Tromsφ belongs to the European Incoherent Scatter Scientific Association.In the experiment,stimulated electromagnetic emission(SEE)spectra were observed.A narrow continuum occurred under cold-start conditions and showed an overshoot effect lasting several seconds.Cascading peaks occurred on both sides of the heating frequency only in the preconditioned ionosphere and also showed an overshoot effect.These SEE features are probably related to the ponderomotive process in the X-mode heating experiment and are helpful for understanding the physical mechanism that generated them during the X-mode heating experiment.The features observed in the X-mode heating experiments are novel and require further investigation.

肉桂酸疏水改性透明质酸的聚集及其光谱性质

通过肉桂酸(CA)与透明质酸(HA)的酯化反应,制备了肉桂酸疏水改性透明质酸(CA-HA)。使用表面张力、芘荧光探针、动态光散射和Zeta电位方法研究了CA-HA在水溶液表面和溶液中的聚集性质。紫外光照射后,CA-HA在250~325 nm处的紫外吸收未出现明显蓝移,说明CA-HA能够抑制CA接枝基团的光异构化,使CA接枝基团保持反式构型。除了CA接枝基团的荧光发射峰外,CA-HA在350~500 nm处还出现了CA接枝基团二聚体的荧光发射峰。随着质量浓度增大,CA-HA能够产生明显增强的聚集诱导荧光。同时,CA-HA乳液在紫外线B(UVB)波段(275~320 nm)具有良好的防晒性能。

松木生物质颗粒预热燃烧特性试验

使用于松木生物质颗粒作为燃料,结合先进的自预热燃烧技术,实现燃料在炉膛内的流态化燃烧。通过千瓦级预热燃烧试验平台,对木本生物质颗粒在不同预热温度下的预热改性进行了全面深入的探索。使用BET、SEM扫描电镜与拉曼光谱带对比的方法对高温生物质半焦的比表面积、总孔容积、氮气等温吸附脱附特性、颗粒表明形态等关键物性参数进行检测和分析。分析结果显示,随着预热温度的升高,氮气吸附量明显增加,说明改性后的生物质半焦具有更多的孔隙结构。结合碳微晶结构分析,松木生物质颗粒在高加热速率下解聚脱挥发导致大分子碳链断裂产生小分子挥发物从而改善反应活性。在燃烧特性方面,改性后的高温生物质半焦可在下行燃烧室内迅速实现稳定燃烧,且燃烧效率高达99%以上。在NO_(x)排放上,所有实验工况均将燃烧温度控制在1 100℃以下避免产生热力型NO_(x)。预热后松木生物质颗粒的NO_(x)排放浓度并未随预热温度的单调变化而增减。842℃时,NO_(x)排放质量浓度达到峰值,随后开始下降。在试验温度范围内,当预热温度设定为705℃时,NO_(x)排放质量浓度达到最低值,即97.79 mg/m^(3)。综上,为确保松木生物质预热燃烧后具有较低的NO_(x)排放和高燃烧效率,推荐的最佳预热温度为705℃。

130t/h型高温高压循环流化床锅炉优化方案

针对锅炉本身存在的一些问题,阐述锅炉优化的方案及相关考虑,对锅炉局部结构进行改造,从而达到初始排放符合环保政策要求,同时更加优化燃烧,使锅炉达到预期的效果.

Multi-process and multi-pollutant control technology for ultra-low emissions in the iron and steel industry

The iron and steel industry is not only an important foundation of the national economy,but also the largest source of industrial air pollution.Due to the current status of emissions in the iron and steel industry,ultra-low pollutant emission control technology has been researched and developed.Liquid-phase proportion control technology has been developed for magnesian fluxed pellets,and a blast furnace smelting demonstration project has been established to use a high proportion of fluxed pellets(80%)for the first time in China to realize source emission reduction of SO_(2)and NO_(x).Based on the characteristics of high NO_(x)concentrations and the coexistence of multiple pollutants in coke oven flue gas,low-NO_(x)combustion coupled with multi-pollutant cooperative control technology with activated carbon was developed to achieve efficient removal of multiple pollutants and resource utilization of sulfur.Based on the characteristics of co-existing multiple pollutants in pellet flue gas,selective non-catalytic reduction(SNCR)coupled with ozone oxidation and spray drying adsorption(SDA)was developed,which significantly reduces the operating cost of the system.In the light of the high humidity and high alkalinity in flue gas,filter materials with high humidity resistance and corrosion resistance were manufactured,and an integrated pre-charged bag dust collector device was developed,which realized ultralow emission of fine particles and reduced filtration resistance and energy consumption in the system.Through source emission reduction,process control and end-treatment technologies,five demonstration projects were built,providing a full set of technical solutions for ultra-low emissions of dust,SO_(2),NO_(x),SO_(3),mercury and other pollutants,and offering technical support for the green development of the iron and steel industry.

冲击地压巷道围岩改性研究

针对巷道围岩改性的研究,主要采用理论解析及室内试验相结合的方法,先分析改性前影响围岩塑性区范围的因素,再利用试验研究改性后不同时间段内试件的力学特性及声发射特征,通过抗压、抗拉、抗剪、声发射实验手段研究围岩改性体破裂力学显现过程。结果表明:改性前围岩塑性区范围受支护阻力、侧压力系数、软化系数、扩容梯度及残余强度等参数的影响;其他条件一定时,提高围岩破碎区的残余强度可减小围岩塑性区的范围;改性体7 d、14 d、28d的抗压强度逐渐增加,最终达到原煤样强度的48.95%,28天的抗拉强度达到原煤样强度,黏聚力与完整煤样相比提高了2.05倍,对围岩塑性圈的改良均有很好的效果;声发射研究得到:7 d、14 d改性体试件的声发射信号变化较强烈,且在各个阶段都有大量的声发射信号产生,在受力情况下试件内部情况复杂,而28 d改性体的声发射信号变化较稳定,主要集中在破坏前后,在时间的作用下改性体的破坏形式逐渐由延性破坏转变为脆性破坏,证明28 d后改性体的强度达到饱和值,在围岩改性强度稳定后才能发现再次进行施工。根据实际情况制定围岩注浆改性方案,并监测围岩顶底板及两帮的移近量,改性后的围岩稳定性增加,变形量减小。

木质素磺酸钙对固井水泥石变形破坏特性的影响及其改性机制

在采动区地面井煤层气抽采工程中,工作面的回采会对上覆岩层产生较大的扰动,进而导致地面井变形破坏,不能有效发挥卸压煤层气地面井的抽采效能。固井技术能够有效延长采动作用下卸压煤层气地面井的寿命,水泥作为影响地面井固井质量的关键因素,其早期强度需满足较高的固井要求,水泥固结后形成水泥石,水泥石的力学性能对维持卸压煤层气地面井的稳定性至关重要。通过添加分散剂提高水泥石的力学性能是改善固井效果的有效途径。针对目前采动作用下木质素磺酸钙改性水泥石变形破坏特性的研究较少,通过开展循环荷载下不同质量分数的木质素磺酸钙改性水泥石单轴压缩试验,探究木质素磺酸钙对卸压煤层气地面井水泥石变形破坏特性的影响及其改性机制。研究结果表明:水泥石纵波波速和峰值应力随木质素磺酸钙质量分数增加呈现出先增加后降低的趋势,而水泥石声发射总振铃计数随木质素磺酸钙质量分数增加呈现出先减小后增大的趋势。随着单轴循环梯级的增加,水泥石的变形模量呈现出强化现象,且初始加卸载循环对变形模量的强化作用最为显著。随着木质素磺酸钙的加入,改性水泥石的破坏模式呈现出拉伸主导→剪切主导→拉伸主导的拉剪组合破坏模式,同时改性水泥石的分形维数呈现出先减小后增大的趋势,表明适量木质素磺酸钙的加入能够有效提高单轴循环加卸载下水泥石的抗破坏能力。随着木质素磺酸钙质量分数的增加,水泥石水化产物之间孔隙呈现出先减少后增多的趋势。适量木质素磺酸钙的加入会促进水泥石中C−S−H凝胶和钙矾石的大量生成,沉淀在水泥颗粒表面相互交织,可显著提高水泥石的峰值应力,对于提高水泥石的力学性能具有积极作用,同时也使得水泥石的孔隙率降低,进而导致水泥石纵波波速增加、循环荷载过程中水泥石累计声发射振铃计数减小。而木质素磺酸钙过量加入时,木质素磺酸钙的引气作用和电性相斥作用在水化过程中占据主导作用,会引入较多气泡,造成水泥颗粒之间间隙的产生,同时抑制了C−S−H凝胶和钙矾石的早期生成,对水泥石的力学性能造成消极影响。此外,会造成水泥石孔隙率增加进而导致水泥石纵波波速减小、循环荷载过程中水泥石累计声发射振铃计数增加。因此,木质素磺酸钙对水泥石的力学性能的影响具有双重效应。

水泥熟料烧成系统能效提升技术的研究及应用

计算分析了现有水泥生产线热平衡支出项中影响热耗的主要因素,针对水泥行业能耗双控目标,提出了能效提升解决方案。现有生产线技改项目应用显示,烧成系统热效率再提升5%~9%,熟料标准煤耗降低10kg/t.cl以上,达到并优于GB 16780-2021标准中熟料单位产品综合煤耗指标1级能效;能效提升的同时,通过应用分解炉自脱硝源头减排技术,分解炉出口CO浓度不超过500ppm,喷氨前NOX本底浓度<350mg/Nm^(3),氨水用量3kg/t.cl的条件下,NOX排放浓度<50mg/Nm^(3),满足国家环保标准要求。

沥青温拌再生剂研究现状与发展趋势

近年来,随着我国绿色交通技术理念的提出,温拌再生技术的应用逐渐成为当前道路建设领域的研究热点之一。温拌再生技术大多是将温拌剂与再生剂分别加入老化沥青中实现温拌再生,它可以降低沥青的拌和温度,提高施工和易性,同时温拌再生沥青混合料的路用性能接近热拌沥青混合料,但其发展时间有限,应用较少。本文综述了近年来国内外温拌再生剂的重要研究进展。首先概述了常用温拌剂的化学结构与特性,及其在沥青温拌技术中的应用,并总结了再生剂与沥青再生技术的发展;其次重点介绍了温拌再生剂的改性方法,并系统梳理了温拌再生剂的改性机理及性能评价方法;最后提出了目前温拌再生剂研究过程中存在的问题,同时展望了温拌再生剂的发展趋势。研究现状表明,温拌再生剂集成温拌剂与再生剂的双重优势,既可以降低拌和温度又绿色环保;温拌再生剂的种类随着温拌再生技术的广泛应用日渐增多,目前温拌再生剂种类分为发泡降黏类、表面活性类和有机降黏类三种;不同种类的温拌再生剂的作用机理大不相同,但主要方式都是通过降低沥青黏度来达到温拌效果,增加老化沥青缺失组分达到再生效果。但国内对温拌再生剂的研究从材料组成上看,其试验和施工过程中温拌再生剂与再生沥青混合料作用所产生的气体对人的身体健康有所危害,仍是不可忽视的问题;同时,如何有效提高温拌再生剂的使用效果,也是未来研究中需重点关注的方向之一。

深蓝光发射碳点的改性及在电致发光器件中的应用

深蓝色电致发光二极管(LED)在显示和照明领域中发挥着至关重要的作用。然而,目前报道的蓝色发光二极管的发射波长仅能达到460~480 nm,难以实现更短波长的发射。柠檬酸和尿素体系碳点作为一种荧光可调的发光材料,在深蓝发光方面具有优势。然而,柠檬酸尿素体系碳点是由富含亲水性官能团的小分子作为前驱体合成,因此,合成的碳点为亲水性碳点,严重限制了其在电致发光器件中应用。在此,本工作提出了一种以柠檬酸和尿素为前驱体,油胺为表面改性剂,一锅法合成疏水性碳点的方法,通过油胺中的氨基与碳点表面的羧基进行酰胺化反应,使油胺的长链烷烃包覆在碳点表面,实现疏水性碳点的可控合成,保持了碳点的深蓝光发射,并将其成功应用于电致发光器件。

金属改性对SSZ-13分子筛CH4-SCR中NO_(x)消除效率的影响

通过不同过渡金属元素改性SSZ-13分子筛的方式制备在高温段高活性的单金属CH4-SCR催化剂.探究了不同改性金属对催化剂NO_(x)转化率的影响,并以此为基础制备多种双金属改性催化剂.采用多种分析技术对不同催化剂的理化特性进行分析,结果表明,在单金属催化剂中In-SSZ-13催化剂有明显优势,最高NO_(x)转化率为38.6%.而1%Cr-5%In-SSZ-13催化剂表现好于其他单金属和双金属改性催化剂,最高NO_(x)转化率为92.4%,并且在500~650℃的NO_(x)转化率在74%以上;1%Cr-5%In-SSZ-13催化剂比In-SSZ-13催化剂有更小的晶粒尺寸以及更多的微观孔隙和活性中心,提升了催化剂的反应物吸附能力;同时1%Cr-5%In-SSZ-13催化剂中出现了结合能明显改变的In^(3+)与Cr^(3+),说明两者之间存在相互作用,使得在CH4-SCR过程中In与Cr之间产生协同催化效果.

氧等离子体改性超高分子量聚乙烯纤维复合材料层间损伤声发射特征分析

为研究氧等离子体改性超高分子量聚乙烯(UHMWPE)/乙烯基酯复合材料层间断裂韧性的损伤模式对其界面性能的影响,首先对不同密度UHMWPE织物进行氧等离子体改性,使用真空辅助树脂灌注成型工艺制备UHMWPE/乙烯基酯复合材料,结合声发射(AE)检测技术对复合材料的Ⅰ型层间断裂韧性(G_(ⅠC))和Ⅱ型层间断裂韧性(G_(ⅡC))进行测试,并对其损伤动态演变过程进行表征和定位。结果表明:界面性能是复合材料层间断裂韧性的主导因素,在G_(ⅠC)和G_(ⅡC)测试过程中,通过在UHMWPE/乙烯基酯复合材料层间预裂纹处产生应力集中,损伤机制表现为张开型和滑移型;低经密UHMWPE织物结构松散,具有良好的改性均匀度,经氧等离子体改性后其制备的复合材料的G_(ⅠC)和G_(ⅡC)分别提高约36.8%~80%、75%~1120%,达到层间增韧效果,同时由于界面结合性能提高,不同损伤模式减少或消除;通过对声发射信号进行聚类分析可有效识别出复合材料基体开裂、纤维/基体脱黏和纤维断裂3种损伤模式及其特征频率范围。

Combustion and NO_(x)Emission Characteristics of Coal Slime Solid Waste at Different Feeding Positions

The NO_(x)emission of coal slime burned in circulating fluidized bed(CFB)boilers could hardly meet the increasingly strict standards in China.Feeding coal slime from the top of furnace led to uneven combustion in furnace and cyclones,short residence time and overheated tail heating surface.The effects of feeding positions on the combustion uniformity and pollutant emission characteristics of coal slime were studied.The experimental results showed that the coal slime combustion was more uniform when feeding from the front wall and longer residence time was conducive to the control of NO_(x)emission.When the boiler temperature and excess air ratio were almost identical,the initial NO_(x)emissions were 45.0 mg·m^(−3)and 70.7 mg·m^(−3)when feeding from the front wall and the top of furnace,respectively;the NO_(x)emission was cut down 36.35%when feeding from the front wall,successfully meeting the ultra-low NO_(x)emission standard of China.The adoption of feeding from the front wall greatly reduced the original emission of NO_(x);the operation costs in the practical applications were saved to a large extent.

Practice on Ultra-low Emission and Energy Efficient Technologies in Coal-fired Power Plants

Restructuring of China's energy mix is accelerating due to factors such as energy security,economic cost,climate change and environmental pressure.Efficient and clean utilization of coal-generated power therefore plays an increasingly important role in solving energy and environmental problems in China.Coal-fired power plants,with Shenhua Guohua Sanhe as one of the pioneers,followed trend of this era and adopted multiple ultra-low emission and energy efficient technologies,striving to be an industry leader in environmental protection,profitability and innovation.As a result,coal-fired power plants have seen ultra-low emissions of air pollutants and record-high energy efficiency,opening up a new era of more efficient and cleaner coal generation.By the end of 2015,Shenhua Group had had 45 ultra-low emission coal units,providing strong support for implementing of the national policy on ultra-low emission and energy efficient retrofit of coal-fired power plants across China.

Environmental consequences of an ultra-low emission retrofit in coal-fired power plants from a life cycle perspective

To make coal-fired power generation more environmentally friendly,China has initiated a series of ultra-low emission ret-rofits to the air pollution control(APC)system of the existing power plants.In this study,a life cycle assessment(LCA)is conducted to analyze the environmental net benefits for the typical ultra-low emission retrofit of a 1000 MW power plant.The key processes,substances,and APC devices are verified and discussed.The results confirm that the retrofit effectively decreases the environmental stress of acidification potential(AP),eutrophication potential(EP),and photochemical ozone creation potential(POCP)by 69%-79%,which can be attributed to significantly reduced emissions at the stack.However,the retrofit has also increased other impact categories by 24%-79%,primarily due to the consumption of additional elec-tricity and adsorbents.The retrofit of selective catalytic reduction,electrostatic precipitator(ESP),and wet limestone flue gas desulfurization devices has a dominant effect on the impacts of EP,human toxicity potential(HTP),and AP.A newly installed wet ESP shows some environmental benefits(only for AP),but causes considerable burdens,in particular for the investigated impact categories global warming potential(GWP),marine aquatic ecotoxicity(MAETP),and abiotic depletion fossil(ADP fossil).The obtained results indicate that the hidden environmental consequences,which are associated with the production of energy and materials,need to be examined more comprehensively to inform the development of ultra-low emission technologies and strategies effectively.