Nitrogen oxides are one of the main atmospheric pollutants and pose a threat to the ecological environment and human health. Selective catalytic reduction (NH3-SCR) is an effective way of removing nitrogen oxides, with the catalyst being the key to this technology. Two-dimensional nanostructured layered double oxide (LDO) has attracted increasing attention due to the controllability of cations in the layers and the exchangeability of anions between layers. As a derivative of layered double hydroxide (LDH), LDO not only inherits the controllability and diversity inherent in the LDH structure but also exhibits excellent performance in the catalytic field. This article contains three main sections. It begins with a brief discussion of the development of LDO catalysts and analyzes the advantages of the LDO structure. The later section introduces the synthesis methods of LDH, clarifies the conversion relationship between LDH and LDO, and summarizes the modification impacts of the properties of LDO catalysts. The application of LDO catalysts used in NH3-SCR under wild temperature conditions is discussed, and the different types, reaction processes, and mechanisms of LDO catalysts are described in the third section. Finally, future research directions and outlooks are also offered to assist the development of LDO catalysts and overcome the difficult points related to NH3-SCR.

In order to solve the problems of uneven flow field distribution in the inlet flue of SCR reactor in the form of upper inlet and lower outlet, abrasion in the center area of catalyst layer and ash deposition near the flue wall, etc. In this study, the flow field simulation and flow field optimization were conducted for a medium temperature medium dust SCR denitration device with a design capacity of 2 000 t/d for a second line cement kiln in Tianjin Zhenxing cement company. The flow field distribution characteristics in the flue of a fullsize SCR reactor were simulated by the Ansys fluent software. A flow field optimization scheme was proposed to set a group of guide grids at the inlet of the flue in the expansion section of the reactor,a layer of uniform distribution plate and a second group of guide grids at the middle of the flue in the expansion section. In the optimization scheme, the guide grid plays an auxiliary role in guiding the diffusion and flow of flue gas, and the uniform distribution plate plays a major role in current sharing. In this study, 50% opening rate, 60° staggered round holes and 60 mm hole aperture were selected as the optimal parameters of the uniform distribution plate through simulation test. The feasibility of the optimization scheme was verified through engineering cases. The calculation results show that the optimized scheme has less burden on the system pressure loss, can effectively improve the uniformity of flue gas distribution, and achieve the technical requirements of catalyst inlet velocity distribution Cv＜15%. The field measurement results after optimization and reconstruction show that the uniformity of catalyst inlet velocity distribution is optimized from Cv=48.5% to Cv=14.5%, the system resistance is increased by 91.5 Pa, and the denitrification efficiency is improved by 11.2% to 86.4%.

根据中温(160～230℃)催化剂研究成果,开展了水泥窑炉烟气中温SCR脱硝技术的应用研究与效率分析.针对不同配方催化剂系列,测试了多种工况条件下NOx脱除效率,并对催化剂的高尘防堵与吹灰技术进行了设计和研究.试验研究表明,中温中尘脱硝效率均可达85％以上,NOx浓度稳定控制＜50 mg/Nm3,催化剂阻力＜200 Pa/层.以上研究为水泥窑炉烟气中温SCR脱硝工程应用奠定基础,即中温中尘SCR脱硝技术是水泥窑炉烟气NOx深度减排的重要措施.

In order to improve the visible light catalytic activity of titanium dioxide (TiO2) and ensure its long-term stability on the surface of concrete, an N-TiO2/SiO2 composite was prepared using tetrabutyl titanate, nitric acid, and modified SiO2 nanospheres as the precursors by a solvothermal method. The effect of nitric acid on the phase composition, morphology and photoelectric properties of the synthesized photocatalytic composites was systematically studied by various characterization methods. The results show that the optimum nitric acid/butyl titanate volume ratio is 1/6. The nitrogen-doped TiO2 nanoparticles were uniformly dispersed on the surface of spherical SiO2 with a diameter of 200 nm. The degradation rate of simulated pollutants (RhB) with pH 5 and 7 exceeded 95% within 30 min and the catalytic effect remained excellent after five repetitions without much weakening. The excellent visible photocatalytic performance can be attributed to the doping of N replacing part of the oxygen atoms in TiO2, forming the energy level of N 2p at the O 2p energy level and reducing the TiO2 energy band gap to 2.99 eV. At the same time, the better dispersion of N-TiO2/SiO2 prepared by this new synthesis method also plays an important role in the improvement of visible light photocatalytic activity.

垃圾衍生燃料(RDF)部分替代传统化石燃料是生活垃圾无害化处置的重要途径.RDF的颗粒形状、尺寸、处置量等会对其在分解炉内的运动轨迹、燃烧过程等造成巨大影响.本文采用CFD模拟研究了处置量、水分含量、粒径大小对RDF在分解炉内运动轨迹、燃尽率的影响.结果表明:当RDF由分解炉中部喂入后,粒径＜10 mm的RDF会随烟气向上运动;粒径≥10 mm的RDF会沉降至分解炉锥部.当RDF处置量由7 t/h增加至15 t/h后,落入烟室的RDF比例由60％增加至67.5％;当RDF水分含量由25％降低至10％时,整体燃尽率由62.94％提高至68.62％;当RDF平均粒径由10 mm降低至5 mm后,RDF整体燃尽率由62.94％提高至85.83％.

Carbonation is an effective method to promote the quality of the steel slag binder. In this article, two carbonation approaches, namely hot-stage carbonation and accelerated carbonation, were employed to leach the metals, and the influence mechanism on the metal sequential leachability of the binders composed of 80 wt% of EAF slag incorporating 20 wt% of Portland cement (PC) was revealed. The carbonate products, microstructures, and chemical states were investigated, and the results indicated that chromium, vanadium, and titanium gradually transformed into inactive phases after two carbonation approaches, while zinc appeared the opposite trend. The sequential leachability of chromium declined with the increase of the carbonation efficiency, in which the exchangeable chromium decreased from 1.99 mg/kg in the A2A binder to below the detection limit in the A2C binder and C2C binder. Hot-stage carbonation treatment facilitated particle agglomeration, minerals remodeling, and calcite formation. The carbonation curing of the steel slag paste resulted in the formation of amorphous CaCO 3 , calcite crystalline and Si-bearing hydrates that covered the pores of the matrix, and silicate structure with a higher disorder. The hot-stage carbonation and accelerated carbonation curing methods were adopted to jointly prevent the leaching of harmful metals and facilitate promising high-volume steel slag-based binders with structural densification and CO 2 storage.

以某5000 t/d生产线为对象,采用流体力学模拟(CFD),模拟了分解炉中气相流、煤粉燃烧和生料分解,分析了分解炉耦合气化炉前后分解炉内流场、温度场的分布情况,以及对生料分解率、煤粉燃尽率的影响.结果 表明:分解炉独立运行情况下,较分解炉耦合气化炉时整体速度较小,出口风速从19.65 m/s降低至16.11 m/s,整体温度下降,出口温度由838℃降低至740℃,煤粉燃尽率大幅度降低,生料分解率降低幅度较小.

介绍并分析了下出风逆流式旋风预热器的原理及优势.在改进了旋风预热系统C1的换热方式后,出口烟气温度相较传统预热器有所降低并且低于出口物料温度,熟料煤耗降低,产量提高.

将CaSO3加热氧化为CaSO4是提高半干法脱硫灰综合利用率的重要途径,而在众多热处理工艺中,回转窑因其能耗低、受热均匀、产品性能稳定等优势是最有望实现工业化的技术之一.本文模拟工业回转窑的工艺过程,对半干法脱硫灰在回转窑不同工况条件下CaSO3的氧化与分解特性进行了试验研究,分析了温度、停留时间、氧气浓度对CaSO3氧化与分解特性的影响.结果表明:随着煅烧温度的增加,CaSO3氧化率显著增大,当温度达到600℃时,CaSO3氧化率达到了60.48％,而CaSO3分解率随温度变化不大;降低回转窑转速有利于提高CaSO3的氧化率,但影响较小;回转窑内氧气浓度对CaSO3的氧化有显著影响,当温度为450℃,氧气浓度由14.0％ 增加至17.5％ 时,CaSO3氧化率由12.18％ 增加至71.95％.

CFB-FGD脱硫灰中CaSO3·0.5H2O含量可达60％以上,对水泥性能影响与石膏有较大不同.对比研究表明,CFB-FGD脱硫灰在适宜掺量时对水泥凝结时间、抗压强度的影响与石膏的影响相当,但超量时容易导致抗压强度显著降低;与适量的石膏复掺性能会得到改善;随脱硫灰掺量的增加,对水泥与减水剂的相容性以及对水泥的体积稳定性无明显不良影响.CaSO3·0.5H2O与C3A反应生成C3A·CaSO3·11H2O,与AFm相类似,呈板片状.CaSO3·0.5H2O与同量的C3A反应会生成较多量的类AFm物,而非柱状、针状的AFt,是导致CaSO3·0.5H2O具有延缓水泥水化的作用,但不如石膏,且超量掺加时易对强度造成不良影响的主要原因.

通过碱激发方式,以矿粉为原料,掺入不同比例的液态排渣制备地质聚合物,研究液态排渣掺量对地质聚合物强度、物相变化、微观形貌、比表面积的影响,并利用L-S相转化法制备条状地质聚合物吸附材料,研究其对水溶液中重金属离子吸附的影响.结果 表明:液态排渣掺量对强度有显著影响,液态排渣掺量(质量分数)为30％时28 d抗折强度最高,达8.7 MPa,28 d抗压强度较空白样仅损失8.9％,达60.3 MPa;XRD,FT-IR及SEM分析结果表明液态排渣掺量影响地质聚合物凝胶结构,液态排渣掺量为30％时凝胶结构为海绵状;BET分析结果表明随着液态排渣掺量的增加,地质聚合物的比表面积呈明显递增趋势,液态排渣掺量为30％时,比表面积约为空白样的2倍,达21.069 m2/g;液态排渣掺量为30％时,条状地质聚合物具有较高的重金属吸附效率,其中Mn2+,Fe3+,Cu2+的最大吸附率分别高达70.8％,90.3％和58.6％.

第八届VDZ国际水泥大会于2018年9月在德国杜塞尔多夫成功举行.VDZ(德国水泥协会)国际水泥大会始于1971年,作为水泥技术领域顶级的国际会议,每年都会吸引国际水泥行业众多科学家和工程师参加.本次会议共有全球水泥生产企业、装备供应商、科研院所等600余人参加,集中讨论水泥生产的最新技术和行业发展面临的共性问题.

硫铁矿的高温氧化是引起水泥生产过程中产生SO2的主要原因.采用一维炉开展了高温悬浮态下硫铁矿氧化的实验研究,并对氧化产物做了X射线衍射(XRD)分析和烧失量检测.XRD分析表明,FeS2在300℃时尚未发生氧化反应,从400℃开始出现Fe2O3的衍射峰,且随着温度升高,FeS2的衍射峰强度逐步减弱,Fe2O3衍射峰强度逐步增强.在400～800℃时,FeS2的氧化产物仅为Fe2O3.基于烧失量的计算表明,在10 s反应时间内,FeS2在300℃几乎没有发生氧化,这和XRD检测结果一致.在400℃和600℃时FeS2氧化率分别达到了50％和85％,800℃时达到了92％.将上述结果应用于水泥生产过程,表明在C1～C4预热器中,约64％的FeS2发生了氧化.

基于某水泥企业入炉煤粉、生活垃圾的工业分析、元素分析结果,从热量平衡角度探讨了不同生活垃圾处置量时分解炉煤粉用量和三次风量的调节.计算结果表明,当生活垃圾处置量由0t/h增加到7t/h、15t/h时,尾煤用量分别降低了8.36％和17.19％,三次风用量分别降低了3.20％和6.04％.

水泥生产中石灰石粉磨和烘干工序具有显著的SO2吸收特性,其属于半干法脱硫.采用固定床实验装置,设计了石英砂作为空白对照,研究了反应温度、石灰石含水率对石灰石低温半干法固硫的影响.结果表明,当石灰石含水率为20％,反应温度从50℃升高到100℃时,石灰石对SO2的吸附量从1.06 mg SO2/g石灰石下降至0.32 mg SO2/g石灰石,随温度升高而降低;其中SO2物理吸附比例从4.72％最高增加至17.81％,随温度升高而增大.当含水率为5％、10％和20％时,在50～100℃内石灰石颗粒对SO2的平均吸附量分别为0.14 mg SO2/g、0.25 mg SO2/g和0.60 mg SO2/g石灰石,其中SO2物理吸附比例分别为38.60％、17.66％和11.22％;SO2吸附量随含水率增加而显著增大,而物理吸附比例随含水率增加而显著降低.采用积分计算的石灰石SO3含量增加值与荧光分析结果相吻合,而与硫酸钡重量法检测结果不一致,表明石灰石低温半干法固硫产物以亚硫酸盐、亚硫酸氢盐等为主,而不是硫酸盐.

The isothermal absorption properties and kinetic model of Cr (VI) and Cr (III) onto ettringite were investigated using the batch adsorption method. IR analysis was used to study the difference and mechanism of the adsorption of chromium ions with different valence states. The results show that the adsorption of Cr(III) onto ettringite at 20 °C agrees with Langmuir’s isothermal model. The ion binding stability was significantly greater than that of Cr (VI). While the adsorption of Cr(VI) onto ettringite agrees with Freundlich’s isothermal model, the D-R model fits the adsorption isotherms of two types of valence Cr ( R 2 > O.994). It can be concluded that the adsorption of Cr (III) onto ettringite is mainly by chemical adsorption and that the adsorption of Cr (VI) onto ettringite is mainly by physical adsorption. Dynamic model fitting and model parameter analyses show that the adsorption of Cr (III) onto ettringite agrees with the pseudo second order kinetics model given by Lagergren. The formation of chemical bonds is the main factor causing the fast adsorption. Cr (VI) adsorption is mainly dominated by liquid film diffusion, and the adsorption rate is much slower than that of Cr (III) adsorption.

以Mn为活性组分,Ce为活性助剂,选取非金属矿物材料(硅藻土、海泡石)部分替代锐钛矿型TiO2载体,采用分布共混法制备了Mn-Ce/TiO2-X低温SCR催化剂,系统分析了硅藻土和海泡石部分取代锐钛型TiO2载体后对Mn基催化剂低温脱硝活性的影响,运用BET、SEM、XRD等测试手段对催化剂进行表征 研究分析表明:锐铁矿型TiO2载体经非矿材料部分取代后,Mn-Ce/TiO2-X催化剂的比表面积、孔结构参数以及表面孔结构形貌均得到改善和提高;Mn-Ce/TiO2-硅藻土和Mn-Ce/TiO2-海泡石催化剂中TiO2的结晶度均有不同程度降低.6％硅藻土和6％海泡石替代部分TiO2载体后,Mn-Ce催化剂的脱硝活性得到不同程度的提高,反应温度在90～180℃时,以上3种方式制备的催化剂SCR脱硝活性顺序为Mn-Ce/TiO2-硅藻土＞Mn-Ce/TiO2-海泡石＞Mn-Ce/TiO2.

对五种热电偶,特别是双层遮热罩热电偶对窑尾系统联接管道内烟气测温误差的计算方法进行了推导.根据计算的需要,由联接管道外壁温度计算出了其内壁温度.计算了五种类型热电偶在窑尾系统各联接管道位置的烟气测温相对误差δ,并与相关计算和实测结果进行了对比.对热电偶测温误差的主要影响因素进行了简单计算分析.分析结果显示,使用热电偶对窑尾联接管道内烟气进行测温时的读数一般比实际值偏小,各种样式热电偶测温的相对误差范围:普通式为7.20％～16.39％,单层遮热罩式为0.69％—6.34％,单层遮热罩抽气式为0.46％—5.23％,双层遮热罩式为0.07％～2.68％,双层遮热罩抽气式为0.04％～2.01％.相比普通热电偶,遮热罩抽气式热电偶的测温准确性大幅度提高.最后对实际生产中热电偶的选配提出了合理建议.

借助X射线衍射(XRD)、红外光谱(IR)、扫描量热(DSC)、扫描电镜(SEM)、电感耦合等离子发射光谱仪(ICP)等测试方法,分析了不同硫酸盐浓度下钙矾石对不同价态Cr离子的固化作用.结果表明:在水化液相中SO42-浓度适宜条件下,钙矾石对低掺量(0.5％)、不同价态Cr离子的28 d固化率均达85％或以上,Cr离子掺量增至2.0％时,钙矾石对Cr(Ⅲ)的固化率变化不大,而对Cr(Ⅵ)的28d固化率降至38.6％;水化液相中SO42-浓度较低时,钙矾石对Cr(Ⅵ)的固化能力有所增强;无论液相中SO42-浓度适宜与否,Cr(Ⅲ)和Cr(Ⅵ)对钙矾石晶体结构和晶体形态均产生了不同程度的影响,且Cr(Ⅲ)影响较Cr(Ⅵ)显著;液相中SO42-浓度不同,Cr离子对钙矾石晶体形态影响程度也不相同,其中,液相中SO42-浓度较低时,Cr(Ⅲ)掺入对钙矾石晶体c轴方向的生长发育有明显促进作用,且在一定程度上提高了钙矾石结晶程度与热稳定性.

水泥窑协同处置固体废物成为行业应对气候变化与节能减排的重要措施.本文通过大量数据收集,介绍3种主要的水泥窑协同处置固体废物技术,以5 000 t/d生产线为基准,构建边际减排成本计算方法,定量分析我国水泥窑协同处置固体废物技术的减排潜力和成本,得到边际减排成本曲线,并给出了相应的建议.