低温腐蚀

<正>水泥熟料在煅烧过程中,所产生的烟气对金属产生腐蚀,按温度分为两类,即高温腐蚀(400℃)和低温腐蚀(400℃)。预分解窑生产过程中,所出现的低温腐蚀通常为水介质产生的化学反应。主要出现在预热器、废热发电、生料磨系统的烟气收尘系统、冷却机废气系统等部位的装备,腐蚀损坏了金属部件和壳体,增加了装备的维修工作量和费用。水泥熟料生产所需的原燃料中,含有不同程度的碱、氯、硫等化合物,在熟料煅烧过程中,这些化合物在高温下挥发,此外,燃料在燃烧过程中产生的CO2和碳酸钙分解产生的CO2,以及原燃料中的水分蒸发产生     

水泥预分解系统碱氯硫循环与富集的过程模拟

水泥窑协同处置生活垃圾时产生的碱、氯、硫等挥发性组分会对水泥窑正常运转产生不利影响,甚至会加剧分解炉和预热器的结皮堵塞.研究了水泥窑协同处置生活垃圾时碱、氯、硫等挥发性组分在预分解系统中的分布规律.通过过程模拟软件Aspen Plus,分别对热盘炉、分解炉和预热器进行过程模拟.模拟结果与现场取样进行化学分析实验得出的结果进行对比分析.结果表明:垃圾焚烧产生的碱、氯、硫随烟气和灰渣一同进入分解炉和预热器,预分解系统中挥发性组分整体较高.C5预热器至C1预热器挥发性组分不断降低,碱和氯主要富集在C4预热器和C5预热器处,硫则主要富集在C5预热器附近,并验证了将Aspen Plus应用于水泥预分解系统中具有很大的实用价值和实际意义.     

烟囱的抗腐蚀

正近年来,水泥生产为降低原燃料费用,大量使用硫含量高的燃料,以及含有硫氯等化合物的低品位原料和工业废料。人们发现,在低温的烟囱最高温度最低的部位出现了严重的腐蚀,不得不在较短的时间内更换。1腐蚀原因水泥熟料煅烧过程中,含有硫、氯等化合物的原燃料产生的SO_2、SO_3、NO_x、HCl和CO_2等酸性气体和粉尘随高温烟气后逸,加热生料和窑     

含高氯,硫,碱原料对水泥生产的影响

本文以一条设计能力为４５００ｔ／ｄ、分解炉燃料比为０．６的带预分解炉和三次风管的干法水泥窑为例，着重分析了含高氯、硫、碱的原料对干法水泥工艺生产操作及熟料质量的影响。     

水泥生产过程中硫的迁移、转化及控制

水泥生产原燃材料中硫含量的增加加重了窑炉烟气二氧化硫排放,分析生产过程中硫的迁移、转化及循环机制,研究采用过程控制的碱硫反应方法,可实现烟气二氧化硫大幅度减排;通过湿法脱硫等末端治理技术,可在高硫工况条件下达到水泥生产二氧化硫超低排放指标要求。     

水泥窑协同处置城市生活垃圾挥发性有害物的控制手段和技术措施

为解决生活垃圾焚烧后进分解炉的废气和飞灰中氯、碱、硫等挥发性有害物的超标问题,并有效防止结皮,应采取窑尾旁路放风措施将氯离子等有害物除去。对南方某公司5000 t/d熟料水泥线日协同处理350 t城市生活垃圾项目旁路放风除氯系统的工艺计算,为水泥窑协同处置生活垃圾的旁路放风除氯系统设计提供设计依据。     

上升烟道的结皮及改造

1结皮形成的机理水泥熟料是物料在1 450℃左右煅烧而形成的, 在此温度下,物料中的硫、氯、碱等组分部分与熟料矿物反应形成固熔体,其余的硫、氯、碱挥发后随窑内烟气向窑尾低温区运动,除部分排人大气外, 大部分将凝结在温度较低的物料中形成循环,经反复循环导致硫、氯、碱在入窑物料中富集,与原始物料相比,预热器最热级物料的硫、氯、碱含量分     

旁路放风生产低碱水泥熟料技术分析探讨

1概述目前,随着工业化生产的大发展和原料资源的日趋紧张,在水泥生产中使用一些含碱、氯、硫量高的原料生产优质熟料,不仅是社会发展对资源利用的要求,而且也是水泥技术及装备本身进步的体现。既要做到这一点,又不影响正常的生产操作,     

连续测试预分解窑高温烟气

水泥预分解窑熟料煅烧过程中,由于原燃料性能和数量的变化,窑尾、分解炉的热烟气的成分也频繁变化,若能适时在线连续测试及时调整烟气的数值,必将提高熟料质量,减少能耗和增加产量. 窑尾所在部位的物料温度一般超过900℃,高温含尘的烟气温度可达1200℃,此外生产中出现的碱、氯、硫等化合物循环富集,以致于一些熔融温度较低的碱氯、碱硫化合物呈现熔相,这些熔融化合物与高温熟料一起,易粘附在测试的取样点上,造成损坏,给测试取样带来困难.     

水泥窑旁路放风技术及余热利用简介

为解决原料中钾、钠、氯、硫等元素对水泥窑生产过程造成的不良影响问题,使系统运行稳定,保证产品质量,采用旁路放风系统是目前解决该问题的最有效途径.旁路放风技术不仅拓宽了水泥生产原料的适应性,还可以生产优质水泥,使产品具有更好的市场竞争力.另外,旁路放风系统高温烟气热损失严重,利用现有余热发电技术将排出的高温烟气用于发电,在保证水泥窑正常生产的同时,还能取得一定的经济效益.     

使用中硫煤生产的问题及其工艺技术措施

由于我国原煤的品位逐年下降,煤中含硫量越来越高,给生产带来了很大的难度.重点就煅烧水泥熟料中由于煤中含硫量升高而出现的问题,进行了现象描述及原因分析,并通过配料方案的调整、窑炉用风的匹配、操作参数的优化等工艺措施,实现了稳定生产.     

水泥及其原材料中碱含量的检测技巧

碱含量的检测是水泥生产和质量控制的重要环节,火焰光度法的检测过程较为复杂繁琐,极易产生误差。简要叙述了火焰光度法检测碱含量的方法原理、检测步骤、结果处理、影响因素及检测技巧等,并重点分析了提高检测准确性的方法和技巧。     

液体三氧化硫生产系统的优化改进

介绍了石家庄炼化分公司液体三氧化硫生产工艺及生产中存在的问题,通过优化工艺参数和改进设备材料,避免了蒸发器和冷凝器的腐蚀泄漏、设备和管道的堵塞,确保了液体三氧化硫系统安全、稳定运行。     

玻璃纤维碱侵蚀机理和耐碱性的探讨

介绍了GRC发展背景,讨论了碱侵蚀机理、化学和物理腐蚀机理及GRC性能和耐久性。通过对玻璃纤维碱侵蚀机理和耐碱性的探讨,得出了水泥基对玻璃纤维的腐蚀作用包括氢氧离子和硅氧四面体的化学作用和静态疲劳过程的物理作用及玻璃纤维因成分和结构的不同有很大的差异等结论。     

Composition and microstructure of a periclase–composite spinel brick used in the burning zone of a cement rotary kiln

The composition and microstructure of a periclase–composite spinel brick used in the burning zone of a cement rotary kiln were investigated and compared to the original brick. The results indicate that cement clinker and alkali salts are two important agents that cause corrosion especially of the bonding phase of refractories in cement rotary kilns. When the molar ratio of alkalis to anions ((Na+K)/(Cl+2S)) is more than one, alkali salts accumulated in the pores, cracks and grain boundaries of the refractory but the severe corrosion of the bonding phase of the refractory did not occur in zones with lower temperatures. The interaction between the cement clinker and the refractory formed a liquid, which, together with alkali salts, improved sintering. The reaction between the cement clinker and the refractory formed a dense reaction layer. Cracks formed in the dense layer and extended through the boundary between the reaction and non-reaction (penetrated) layers by mechanical and thermal stress, which caused the spalling of the reaction and coating layer from the refractory. The recurrence of this process during service leads to degradation of the refractory.     

地质聚合物的土木工程耐久性能的研究进展

地质聚合物是由硅铝酸盐材料通过碱激发形成,具有网络结构和无定形性质的胶凝材料。由于地质聚合物具有优于普通硅酸盐水泥的力学性能,并且制备过程中CO2排放量较少等优点,被认为是硅酸盐水泥的良好替代品。尽管相当部分的研究者认为地聚物的耐久性也要好于普通硅酸盐水泥,但其他研究者对此持怀疑态度并认为很多方面还需进一步的研究。本文回顾了近几年有关地聚物耐久性研究的现状和进展,总结和讨论了地聚物的吸水性、碳化、硫酸盐侵蚀、酸腐蚀、碱-集料反应和氯离子渗透等耐久性能及其作用机理的研究成果,并提出了现有研究存在的主要问题。     

Alkali resistance,microstructural and mechanical performance of zirconia-coated basalt fibers

Sol–gel approach was developed to apply zirconia coatings on basalt fibers. Dense or porous ZrO₂ coatings were obtained, depending on the process parameters. The alkali resistance of uncoated and ZrO₂-coated basalt fibers in alkali solution was studied. The morphology, elemental and phase composition of etched fibers as a function of etching time were studied by means of a set of analytical methods. A scheme of etching of as-received and coated basalt fiber was proposed. Zirconia coating slows down the corrosion of basalt fiber in alkali solution. The denser zirconia coating slows down the corrosion to a higher extent than the porous coating. The uncoated and coated basalt fibers were tested in mini composites with cement matrix. It was shown that the surface of the coated fiber is affected by the alkaline medium of the cement matrix to a smaller extent than the surface of as-received basalt fiber.     

JNS-1改性氯丁胶乳水泥砂浆在碱厂的应用

介绍了JNS-1改性氯丁胶乳水泥砂浆的特性及其在碱厂防腐方面的实际应用，通过多年的实践证明JNS-1改性氯丁胶乳水泥砂浆在碱厂土建及设备防腐方面的性能优越，可以给使用者带来显著地经济效益。     

Fabrication and characterization of a mullite-foamed ceramic reinforced by in-situ SiC whiskers

In this study, a new mullite-foamed ceramic, reinforced with in-situ SiC whiskers (MCS) and applied as the insulating lining of thermal equipment used in cement production, was investigated. Compared with a conventional mullite-foamed ceramic (MC), the MCS phase composition, microstructure, compressive strength, thermal conductivity and alkali corrosion resistance were investigated by using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and Factsage® software. The results showed that after being fired in granular coke, the SiC whiskers formed into MCS struts and were distributed in the pores between the interconnected needle-like mullite. Although the formation of SiC with higher conduction slightly increased MCS thermal conductivity, it significantly enhanced the compressive strength and alkali corrosion resistance of the foamed ceramic. Compared with the MC, although the MCS had higher bulk density (3.9%), and higher thermal conductivity (9.5% at 800 °C), it was more important that greatly improved compressive strength (by 60%) and better alkali corrosion resistance was achieved.     

Chemical Interactions Between Cement and E-Glass Fibers with a CaO–BaO–SiO2–TiO2 Coating

E-glass fibers were coated with a 15CaO–15BaO–20SiO₂–50TiO₂ thin film by the sol–gel method. Mechanical and chemical tests were performed on coated and uncoated fibers in cement and cement extract solutions to investigate the interactions between cement and gel-glass film. The results show that the resistance of E-glass fibers to the alkali cement medium is enhanced by the 15CaO–15BaO–20SiO₂–50TiO₂ coating. The significant roles of TiO₂, CaO, and BaO in the protection fibers from the alkaline attack of cement are described. Some evidence is presented that the alkali corrosion of the coated fibers results in the formation of a thick and compact Ti film that suppresses further corrosion reaction.