A Model for Predicting the Erosion Rate Induced by the Use of a Selective Catalytic Reduction Denitrification Technology in Cement Kilns Flue Gas

Selective catalytic reduction(SCR)is a technology by which nitrogen oxides are converted with the aid of a catalyst into diatomic nitrogen and water.It is known that the catalyst can be easily eroded if a cement kiln with a high-dust content is considered.To understand this process,numerical simulations have been carried out considering a single catalyst channel in order to study the collision and erosion of fly ash and catalysts at meso scale.Based on a response surface methodology,the effects of five factors on the erosion rate have been studied,namely,the catalyst particle velocity,the particle size,the particle concentration,the incidence angle and the catalyst porosity.The results show that the influence of particle velocity,particle size and particle concentration is statistically significant and the particle size and incidence angle have a significant effect on the erosion rate.A quadratic polynomial prediction model for the erosion rate of honeycomb catalysts in cement kiln SCR reactors is finally proposed to support the future optimization of these systems.

Effects of Municipal Sewage Sludge on Fixation of Cr,Ni,Cu,and Zn during Co-processing of Heavy Metal-containing Waste in Cement Kilns

Cement raw meal with MSS and different heavy metals was blended to examine the fixation ratios, chemical species, and cement crystalline phases in clinkers. The results showed that blending MSS could decrease the fixation ratio of Cr, Ni, Cu, and Zn in the produced clinker by 5% to 25%. And Cr, Cu, and Zn were mainly incorporated into clinkers as metal silicates, Ni was mainly solubilized in Mg O to form magnesium nickel oxides, and the transition phases were mainly metal aluminum oxides as indicated by X-ray diffraction. The reduction of fixation ratios was likely attributed to the presence of impure elements, such as sodium and phosphorus in MSS. In addition, high concentrations（eg, 1.7 wt%） of chlorine in MSS led to metal chloride formation that could vaporize Cu, Cr, Ni, and Zn. To summarize, introducing MSS would decrease the fixation ratios of heavy metals due to the presence of impure elements, such as sodium and phosphorus and chlorine.

Present Synthesizing Situation and Application Mechanism of Hercynite in Cement Kilns

The magnesia -hercynite bricks offer a new lining to rotary cement kiln. They are well adopted and widely used in the high temperature zone of cement kiln, and have obtained good performance at rigorous and severe working conditions. The synthesis of hercynite requires a suitable atmosphere with proper O2 partial pressures which makes sure FeO can stably exist at the synthesizing temperature. Current industrial production of hercynite mainly adopts fused method. The other method, sinte- ring method, is not mature and needs further research. The magnesia - hercynite brick shows high hot toughhess, high adhesion strength to kiln crust, and good corrosion resistance to alkali salt in cement kilns. The mismatching of thermal expansion between magnesia and hercynite can improve the thermal shock resistance of the bricks, but the oxidation of partial Fe^2＋ , the high temperature solution, and low temperature exsolution of transgranular secondary spinel lead to cubical expansion, .formation of more cracks, and poor thermal shock resistance of the bricks.

Numerical analysis of behavior of active layer in rotary kilns by discrete element method

The behavior of the active layer of material bed within rotary kilns plays a key role in industrial applications.To obtain its influences on industrial process,different regimes of particle motion have been simulated by discrete element method(DEM) in three dimensions under variant rotation speeds,filling degree,based on the background of induration process of iron ore pellets.The influences of the mentioned factors on the maximum thickness of the active layer and the average velocity of particles have been investigated.The average velocity of particles increases with Froude number following the power function over a wide range,and the maximum thickness rises with increasing rotation speed in a way of logarithm.The influence of the filling degree f on the maximum thickness exhibits a good linearity under two classic regimes,but the increasing of the average velocity of the active layer is limited at f=0.4.This basic research highlights the impact of the active layer within rotary kilns,and lays a good foundation for the further investigation in mixing and heat transfer within the particle bed inside rotary kilns.

Digital Kilns and Furnaces——the Development Direction of Industrial Kilns and Furnaces in the 21st Century

The digital manufacturing theory is applied to the special manufacturing equipments——industrial kilns and furnaces; the concept of digital kilns & furnaces is put forward. The present status of research and application for digital technologies in fuel industrial kilns & furnaces is also introduced. Then,take the case of gas fuel kilns & furnaces,their main key technical issues are discussed. Digital kilns & furnaces as an important constituent of the digital equipments are the crucial base of the digital manufacturing. The value of research on digital kilns & furnaces and the application prospect are undoubted. It will improve product quality,reduce the manpower cost,enhance product market competitive ability,promote comprehensively tradition industries such as ceramics,metallurgy industry,and so on.

Key Points of Monolithic Lining Engineering of Rotary Kilns

There are many factors affecting the monolithic lining engineering of rotary kilns,resulting in the difficult quality control.In this paper,the key points of the whole lining engineering were discussed from the aspects of lining structure design,personnel preparation,site construction management,maintenance and baking.

Corrosion of Disposing Urban Domestic Wastes on Refractories for Cement Rotary Kilns

Corrosion of burning urban domestic wastes to alkali-resistant bricks and spalling-resistant high alumina bricks was researched by static crucible method and SEM in order to choose refractories for cement rotary kilns for collaboratively disposing wastes. The result indicates that the main corrosion mechanism is slag permeation and corrosion ; the emitted high temperature gases containing alkali, sulfur and chlorine during burning the wastes re- act with refractories forming low melting point sulfate, chloride and compound salts, which metamorphose the refractories, and the loose metamorphic layer is easy to spall under thermal stress. So, corrosion resistance and spaUing resistance shall be taken into account when choosing refractories for cement rotary kilns for collaboratively disposing wastes. It is suggested that decomposition furnaces should adopt spaUing resistant high alumina bricks and anti-coating SiC castables, and preheating equipment should adopt high strength alkali-resistant bricks and castables.

Suggestions on Refractories in Nonferrous Metal Smelting Furnaces/Kilns

This paper introduces the refractories used in various nonferrous metal smelting equipment in China and the existing problems, and puts forward suggestions on the material of refractories, application of new technologies and production management of refractories, etc.

Damage Mechanism of Silicon Carbidemullite Bricks for Transition Zone of Cement Rotary Kilns

In order to improve the service performance and explore the damage mechanism of silicon carbide-mullite bricks for the transition zone of cement rotary kilns,the phase composition and the microstructure of a used brick in the transition zone of a cement rotary kiln were analyzed by XRD,SEM and EDS.The results show that the liquid and alkali vapor phases generated by the reaction between cement materials and the silicon carbide-mullite brick mostly enter the silicon carbide-mullite brick through the pores;meanwhile,Ca+and K+in the cement penetrate through the liquid maintaining a high chemical potential energy to dissolve Al2O3 and SiO2 at the top of the liquid phase thus enhancing the phase penetration;with the decreasing temperature,crystals such as gehlenite,potassium feldspar and potassium chloride are precipitated,which destroy the original structure and increase the difference of thermal expansion coefficient between the high temperature dense end and the metamorphic layer thus resulting in cracks,spalling,and rupture.

A History of Industrial Kilns and Furnaces——Lessons for Future Energy Conservation and Environmental Protection

This is a historical compilation and analysis of the world-wide development of kilns and furnaces, covering those ones ranging from ancient earthenware kilns to modern high-tech furnaces、 including nuclear reactors and fuel cells. Special emphasis is on energy conservation and environmental protection. the historical lessons from which can be applied to future activities.

Direct-bonded Magnesite-Chrome Bricks for Kilns and Furnaces of Building Materials Industry

JC 497-92 (96)1 Contents and Applied ScopeThis standard specifies the classification, shapes and dimensions, technical requirements, test methods, inspection rules, marking, packing, transportation, storage and quality certificate of direct-bonded magnesite-chrome bricks for building materials industry. This standard is applicable to the direct-bonded magnesite-chrome bricks for cement kiln, glass melting tank and other industrial furnaces.2 Normative ReferencesGB 2997: Test method for the apparent porosity, water absorption, bulk density and true porosity of dense shaped refractory productsGB 5070: Chemical analysis method for magnesite-Chrome refractoriesGB 5072: Test method for cold crushing strength of dense shaped refractory productsGB 5989: Test method for refractoriness under load of dense shaped refractory products (Differential, with rising temperature)GB 7320: Test method for thermal expansion of refractory productsGB 7321: Sample preparation for testing of dense shaped refractory productsGB 10324: Type definition of refractory productsGB 10325: Piling, sampling, acceptance, storage and transportation of refractory products

Multi-Objective Adaptive Optimization Model Predictive Control:Decreasing Carbon Emissions from a Zinc Oxide Rotary Kiln

The zinc oxide rotary kiln,as an essential piece of equipment in the zinc smelting industrial process,is presenting new challenges in process control.China’s strategy of achieving a carbon peak and carbon neutrality is putting new demands on the industry,including green production and the use of fewer resources;thus,traditional stability control is no longer suitable for multi-objective control tasks.Although researchers have revealed the principle of the rotary kiln and set up computational fluid dynamics(CFD)simulation models to study its dynamics,these models cannot be directly applied to process control due to their high computational complexity.To address these issues,this paper proposes a multi-objective adaptive optimization model predictive control(MAO-MPC)method based on sparse identification.More specifically,with a large amount of data collected from a CFD model,a sparse regression problem is first formulated and solved to obtain a reduction model.Then,a two-layered control framework including real-time optimization(RTO)and model predictive control(MPC)is designed.In the RTO layer,an optimization problem with the goal of achieving optimal operation performance and the lowest possible resource consumption is set up.By solving the optimization problem in real time,a suitable setting value is sent to the MPC layer to ensure that the zinc oxide rotary kiln always functions in an optimal state.Our experiments show the strength and reliability of the proposed method,which reduces the usage of coal while maintaining high profits.

Research on Remote Fault Detection System of Ceramic Kiln Based on 5G and IoT Technologies

In order to overcome the defects of the existing technology that the detection of ceramic electric kiln faults takes a long time and costs a lot,an electric kiln control and fault detection device was designed.The working process of the device includes detection module,control module,start⁃stop module and switch module.The detection module detects the resistance circuit and sends a fault signal to the control module.The control module generates stop signal and fault information according to the fault signal,and starts the electric kiln when the fault signal is not received within the preset time.The start⁃stop module can monitor the internal temperature of the electric kiln and control the closing status of the switch module.The switch module is used to control the connection status of AC power and each resistance circuit in the kiln.Based on the 5G DTU or 5G module,the control module could send the information to mobile terminal under the ultra⁃reliable and low⁃latency communication(uRLLC)technical characteristics of 5G communication.

固体废物的工业窑炉协同处置进展

工业窑炉协同处置固体废物是降低碳排放的重要途径。将固体废物作为替代燃料或原料在现有高温窑炉中进行处置,不仅可以减少污染物排放,还可实现固体废物的减量化、无害化和资源化利用。本文介绍了水泥窑、电厂燃煤锅炉、钢铁冶炼窑炉、煤气化炉等工业窑炉协同处置固体废物技术的现状,分析了多氯代二苯并-对-二口恶英/多氯代二苯并呋喃(PCDD/Fs)和重金属两类典型污染物的排放特征,指出了该技术当前存在的问题,并对其发展方向进行了展望。

钢铁工业含锌尘泥回转窑处置技术的应用进展

钢铁冶炼过程(炼铁、炼钢)会产生大量的含锌尘泥,该尘泥不宜直接返回炼铁工序,一般以厂内长期堆存或外委等方式进行处理。随着我国钢铁企业“固废不出厂”“循环经济”“绿色制造”等新理念的深入推进,在钢铁厂内部采用新型回转窑技术直接处置含锌尘泥成为大势所趋。本文介绍了传统回转窑处置含锌尘泥技术的工艺流程,从原料、生产过程和产品特点等方面分析其不足,提出采用原料造球、多喷孔分级进风等创新技术的新型回转窑处置技术,该技术明显提高了回转窑处置能力,缓解了回转窑结圈,已相继在永锋钢铁、八一钢铁、诚钰环保等钢铁企业和环保公司稳定运行,产生了良好的经济与社会效益。该技术在多固废协同处置、热渣干式冷却等方面具备应用前景。

基于有限元的热力耦合场匣钵运动分析与优化

为解决装有锂离子电池正极材料的匣钵在辊道窑烧结过程中易出现异常横向运动使匣钵破损的问题,本研究通过分析匣钵异常运动特性的影响因素对其进行优化。首先,利用Solidworks软件建立辊道-匣钵传动系统简化模型,对匣钵进行受力分析,推导出匣钵发生异常横向运动的原因是辊棒的弹性变形;其次,通过Abaqus软件进行有限元仿真,对比分析热力耦合场和重力场下匣钵的位移曲线以及辊棒的受力情况。结果表明,与重力场相比,热力耦合场的辊棒弹性变形量更大,且热力耦合场匣钵横向位移在0~1 s内相对重力场增大,而在1~5 s内相对重力场减小,说明在温度和重力共同作用下所引起的辊棒弹性变形是导致匣钵异常横向运动的主要原因。在此基础上,设计了一种匣钵传动机构,包括辊棒支撑机构、匣钵夹紧装置及匣钵挡齐装置,并通过对比生产验证了改进机构的可行性。本研究对在辊道窑烧结过程中匣钵异常横向运动的影响因素进行分析并提供了一种改进机构,有助于推进锂离子电池正极材料生产设备的发展。

基于贝叶斯优化XGBoost的石灰窑气预测

石灰窑是碳酸钙产业的关键生产设备,窑气中的CO_(2)是生产碳酸钙的原料,CO_(2)浓度直接影响碳酸钙产量,然而石灰窑气浓度依靠产品产出后采样化验得到,存在严重的滞后性,无法作为石灰窑在线工艺参数调整的依据。因此提出一种基于贝叶斯优化的eXtreme Gradient Boosting石灰窑气浓度预测模型BO-XGBoost,根据历史数据预测1 h后的窑气浓度,为生产工艺参数的调整提供依据。该方法首先对石灰窑传感器数据集中的缺失值、异常值进行剔除、插补,然后统一窑气浓度检测历史数据的时间尺度,构成石灰窑气监测数据集,在此基础上提出针对石灰窑气的BO-XGBoost模型。模型经训练后,采用实际生产数据进行测试,并与Light Gradient Boosting Machine(Light-GBM)模型、Category Boosting(Catboost)模型预测结果进行比较,结果表明,所提模型可以实现高维数据集的超参数快速优化,且预测模型有较好的精度,均方根误差(RMSE)达到0.70,平均绝对百分比误差(MAPE)达到2.03%。

从磁州窑看北方青花五彩工艺的形成与特点

清末民国时期,磁州窑为了在激烈的市场竞争中生存下来,持续不断地开展了瓷业改良活动,在改良中以南方的景德镇窑和醴陵窑为主要学习目标,迅速抛弃了白地黑花的传统,先是在清末形成了青花“一枝独秀”的局面,民国十九年之后,复又形成了五彩装饰的“满园春色”。同时,在磁州窑与北方多地窑口的相互交流中,逐渐形成了以磁州窑为代表的近代北方民间青花五彩瓷器的工艺特点。

气候变化下窑居建筑屋顶适宜性改造研究

调研发现陕北地区自2010年以来降水量开始呈现明显增加的趋势,而传统窑洞屋顶缺少良好的防水设计,易导致窑洞在经受暴雨时漏水甚至坍塌。村民采取在原屋顶上加建彩钢板的改造方式防雨,然而这种窑洞屋顶构造的自更新不仅未能充分解决屋顶防水问题,还在一定程度上破坏了窑洞村落的传统风貌。以陕北地区传统民居的典型代表窑洞为研究对象,通过调研测试与软件模拟分析窑洞屋顶加盖彩钢板构造对室内热环境的影响,发现加盖彩钢板能够提升屋顶的耐久度和防雨性能,但是不能改善室内热环境,并且不能充分融入到传统的乡村环境中。在此基础上提出了新型窑洞屋顶构造,以期进一步改善屋顶防水性能并延续传统民居建筑风貌,为后期窑居建筑更新改造提供参考。