露天条形煤堆防自燃监控系统设计

火电厂储煤场会存在煤自燃问题,煤的自燃与复杂环境和煤自身特性有关。无论何种原因,煤的自燃都会给电厂带来重大损失,甚至对人员生命安全造成巨大危害。研究发现,煤自燃过程中的温度变化非常明显且具有代表意义。因此,有效的监控储煤温度,对自燃临界温度进行及时预警,可以使工作人员对储煤进行及时处理,从而达到消除自燃隐患、有效保证火电厂原料的生产安全及降低煤炭不必要的损耗。本文以煤堆温度检测和无线传输为主要设计重点。在设计中,采用STC89C52单片机控制DS18B20温度传感器和NRF24L01+无线数传模块。该系统精度高、测温范围广、无线传输距离远。     

燃煤发电厂储煤场自燃热损失的评估

煤炭周转不合理导致了自燃在燃煤发电厂露天储煤场频频发生,降低了入炉煤的发热量,增加了灰分,直接影响锅炉机组运行的安全性和经济性.为了掌握不同存煤阶段煤堆热损失的变化规律,本文以煤场某典型煤种为研究对象,开展了煤场温度监测试验,并在试验的基础上建立自燃热损失评估的数学模型.研究结果表明,存煤初期煤堆热损失以线性函数规律增加,入场存放30d后煤堆热损失以幂指数函数增长的趋势急剧增加,因此应在30～40d内完成入场煤的周转,实现合理存煤、用煤,减少入炉前发热量的损失,为开发燃煤发电厂储煤场自燃热损失评估系统、降低发电成本提供奠定了基础.     

柠檬酸盐凝胶自燃烧法合成超细粉体

溶胶-凝胶自燃烧法兼顾了溶胶-凝胶法与自燃烧法的优点,是一种很有应用前景的制备复合氧化物纳米材料的低温合成方法.介绍了柠檬酸盐凝胶自燃烧法的基本原理、反应配比的理论计算,分析了pH值、加水量、柠檬酸/硝酸盐、反应温度等因素对柠檬酸溶胶、凝胶的影响.综述了溶胶-凝胶自燃烧法在制备材料中的应用现状.     

棉花的热危险性及其影响因素的研究

为评估棉花的热危险性,采用自热和自燃点测试装置,研究了含水量、含油量、堆积密度等对棉花自热性能的影响规律,以及立方体金属网篮的不同体积对棉花自燃温度的影响。结果表明:含水量、含油量及堆积密度越高,棉花内部温度越高,热危险性越大。但水的质量分数在0~50%的范围内,脱脂棉和长绒棉两种棉花均不属于自热物质;当油的质量分数为5%和10%时,长绒棉发生自燃时最高温度分别为635.6 ℃和539.7 ℃,属于自热物质;当油的质量分数为5%、10%和15%时,脱脂棉最高温度分别上升至161.7、169.8 ℃和184.1 ℃。立方体金属网篮的体积越大,棉花的自燃温度越低;研究发现,立方体网篮体积的对数（logV）和自燃温度的倒数（1/T）成线性关系,根据拟合曲线可预测不同体积下棉花的自燃温度。     

不同堆放方式下冷藏间内果蔬水分耗散过程的数值研究

果蔬在冷藏期间的水分耗散是影响其贮藏品质和经济性的一个重要因素。本文运用CFD分析方法,探讨了果蔬的四种堆放方式对冷库内空气区平均速度、各区域平均温度、相对湿度及果蔬冷藏期间水分耗散的影响。结果表明：对于降低货物区的温度,减少果蔬冷藏期间的水分耗散,垂直间距形堆放是最佳的堆放方式。     

利用低温热管技术防止圆形封闭煤场煤堆自燃

提出了一种圆形封闭煤场防止煤堆自燃的方法,通过在挡煤墙地带设置重力式低温热管来释放煤的氧化热,运行过程稳定,无能耗。该方法人工维护量小,初投资低,易于实施,因此,具有很好的应用前景。     

热浸温度对不同热浸镀层力学性能的影响

研究了不同热浸热浸温度对纯锌镀层和Zn-11%Al-3%Mg-0.2%Si-0.02%RE合金镀层中元素分布、镀层厚度的影响并对两种镀层中的物相进行了分析,同时研究了不同热浸温度对镀层试样抗弯曲强度和硬度的影响。结果表明两种镀层的厚度都随热浸镀温度的升高而减薄。随着热浸镀温度的升高,扩散阻碍层被迅速破坏,导致合金镀层中的Al含量出现了降低的现象。通过XRD结果分析得出,纯锌镀层内部主要包括Zn和FeZn8.75两种物质,合金镀层内部则主要包括Zn、Fe4Zn9、MgZn2、Al5Fe2。抗弯曲试验和硬度测试结果表明,两种试样的抗弯强度都随热浸温度的升高而降低。纯锌镀层试样的硬度随热浸温度的升高呈现降低趋势,而合金镀层试样的硬度则随热浸温度的升高呈上升趋势。     

基于电厂锅炉排烟温度控制的研究

现阶段,我国的电厂锅炉排烟大部分都存在温度过高现象,这在很大程度上影响并制约了我国电厂开展节能工程的进度。锅炉排烟的温度过高不但加大了电厂的资金投入,还在很大程度上限制了我国电厂开展节能工程,所以,一定要认真分析影响电厂锅炉排烟的温度过高因素,探讨降低温度的有效措施。本文主要就导致电厂锅炉的排烟温度过高因素进行分析,探讨其有效控制措施。     

钴含量对锰锌铁氧体磁导率温度稳定性的影响(英文)

采用溶胶凝胶自燃烧法制备了Mn0.4Zn0.6-xCoxFe2O4铁氧体,研究了钴掺杂对其结构和磁性质的影响。将自燃烧法制备的粉末进行1,150℃烧结。利用X射线衍射仪对制备的粉末测试发现,Mn0.4Zn0.6-xCoxFe2O4系列铁氧体都具有尖晶石结构。利用VSM对铁氧体进行磁性测试,发现饱和磁化强度与晶格常数的变化规律一致,在钴含量为0.2时,都取得最大值。通过μi-T曲线发现,初始磁导率随着钴含量的增加而降低,居里温度是一个常数。而且,钴含量可以调节磁导率的温度稳定性,在钴含量为0.3时,磁导率具有优良的温度稳定性。基于铁氧体中离子分布的原理,阐明了钴掺杂对铁氧体磁导率温度稳定性的作用机理。     

纯金属真空蒸馏研究(Ⅱ):基本规律及应用

对纯金属Ph，Cd，Zn在不同温度和压力下的挥发速率进行了数学模型和实验研究，计算结果和实验结果吻合良好。温度升高，压力降低，挥发速率增加。当压力降低到“临界压力”以下，压力的降低对挥发速率影响很小，此时，表面挥发温度低于液体内部温度，液体金属内部的传热过程控制整个蒸发过程，由此确定了工业应用的真空度和挥发温度。对直接测压法，Knudsen法和Langniur法等测压方法进行了比较。     

我国煤矿矿井防灭火技术研究综述

总结了近年来我国在煤矿矿井火灾预测预报理论及方法、矿井煤炭自燃火源区域探测方法、矿井防灭火技术、外源火灾检测及防治和矿井防灭火决策系统等方面的研究和应用进展,分析了我国在煤矿矿井防灭火技术研究和应用中存在的问题。     

某电厂褐煤和印尼煤掺烧经验介绍

介绍了某电厂锅炉混煤掺烧实用经验、运行技术和安全措施;总结了实施混煤掺烧过程中出现的问题;提出了部分解决问题的方法,并对混煤掺烧管理方面给出了具体建议,为燃煤电站实施混煤掺烧提供有益参考。     

火电厂煤场自燃监测系统探讨

分析了煤场自燃的机理,提出了监测煤场的方法和修正过程；构成了一套监测控制系统,采用各种数据比对说明煤场监测的难点和关键点；解决了煤场自燃无法控制的问题；应用表明系统能准确预先发现存在自燃的可能点,有效地控制了煤场自燃的发生,对火电厂煤场和各港口煤场都有较大的推广应用价值.     

Effects of intrinsic properties,particle size and specific surface area on WOP and spontaneous combustion susceptibility of coal

This study examines the effects of intrinsic properties, particle size, and specific surface area (SSA) of coal on spontaneous combustion. Moreover, it analyzes the underlying mechanism of spontaneous combustion from particle size, SSA and gas adsorption perspectives. The susceptibility of coal to spontaneous combustion is studied by wet-oxidation potential (WOP) method. Coal residues left after the WOP experiment are analyzed for change in structural and compositional behaviour. The study revealed an inverse relationship between the particle size and SSA of coal. Spontaneous combustion susceptibility increased with increase in volatile matter and decreased with increase in fixed carbon content of coal. The optimum moisture content of coal resulting maximum spontaneous combustion tendency is determined 6%. Decrease in particle size and increase in SSA augmented the spontaneous combustion propensity of coal. With decrease in coal particle size from 425 to 850 to < 38 µm, the mean D₅₀ value decreased by 27 times, the mean SSA increased by 42 times and coal spontaneous combustion susceptibility increased almost by 2 times. Critical coal particle size is determined 38–74 µm (D₅₀ = 50.56 µm), below which no appreciable change in oxidation rate is observed. Moreover, two models are developed to predict the spontaneous combustion susceptibility of coal based on particle size (D₅₀) and SSA.     

自燃煤矸石胶凝材料中钙矾石形成研究

采用XRD分析了自燃煤矸石胶凝材料中活性Al2O3在不同因素影响下水化形成钙矾石的情况.研究结果表明,在相同条件下芒硝存在,时自燃煤矸石中活性Al2O3水化生成钙矾石,而含等量硫的石膏存在时水化浆体中不但有水化产物钙矾石还有未反应的石膏;胶凝体系中不含熟石灰时,活性Al2O3水化首先生成石膏,随着水化的进行再转化成钙矾石,而在有熟石灰时水化则直接生成钙矾石;矿渣促进了自燃煤矸石中Al2O3水化形成钙矾石.     

特定纳米结构燃烧催化剂在电厂煤粉炉中使用的效果

为考查具有特定纳米结构燃烧催化剂在电厂煤粉炉中使用的效果,在火电厂进行了一系列试验．结果验证了该助燃剂适用于煤粉炉,有增加煤的发热量以及节能降耗的效果,催化作用时效持续24小时以上;但仍有添加量偏大等问题,有待后续试验完善。     

Aqueous three-phase foam supported by fly ash for coal spontaneous combustion prevention and control

This work deals with the preparation and characterization of fly ash (FA) supported aqueous three-phase foams containing N₂ for coal spontaneous combustion prevention and control. Uniform and dense three-phase foams featuring FA contents between 20 wt.% and 33 wt.% are prepared in batch mode using a home-made foam generating column with an internal Venturi tube. The effect of FA on the foamability, static and dynamic stability of the three-phase foams is discussed. Compared with two phase foams, the FA supported three-phase foams manifest higher static and dynamic stability, which increases with the FA content. Base on the excellent static and dynamic stability, a structure model to attach FA particles at the N₂–water interfaces of the three-phase foams was proposed to elucidate the observed behaviors. The as prepared FA supported three-phase foams, exhibiting excellent coal fire extinguishing characteristic, can be used as a promising fire extinguishing material, especially for preventing the large coal area spontaneous combustion or extinguishing fire in high and unknown locations in goaf.     

Heat effect of the oxygen-containing functional groups in coal during spontaneous combustion processes

The heat generated from the reactions of oxygen-containing functional groups in coal has been studied using organic chemistry and quantum chemistry analysis methods. Structural models of the oxygen-containing functional groups in coal were established and used to analyze the reactions of these groups during spontaneous combustion. The Gibbs free energy and enthalpy changes associated with these reactions were determined using quantum mechanical analysis, and the results indicated that the dehydration and dehydrogenation reactions of the hydroxyl groups in coal were only mildly exothermic, whereas reactions involving the oxidation of the carbonyl groups were much more exothermic. In contrast, reactions resulting in the generation of carbon monoxide were endothermic. By comparing the heat release characteristics of the reactions of the oxygen-containing functional groups with the levels of oxygen consumption and gas production, as well as temperature profiles of the reactions, it was concluded that the decomposition of oxygen-containing functional groups is critical to the production of heat during the initial stages of the spontaneous combustion of coal and that oxidation does not occur during this period. These results also explain why the temperature of coal rises slowly during the initial stages of its spontaneous combustion.     

煤和市政污泥掺烧的灰熔融特性研究

通过利用Factsage热力学模拟软件、X射线衍射（X-ray diffraction,XRD）等分析方法,对煤与3种市政污泥按不同比例掺混后混合燃料的灰熔融特性进行研究。结果表明,在污泥添加量不超过10%时,混合燃料的灰熔点随着污泥加入比例增大而降低,这是由高温条件下碱性氧化物熔融所形成的共融体,以及磷矿物反应生成的非晶态矿物的共同作用导致的;灰熔融温度的预测趋势与实际测定数据的规律基本一致;煤中掺混污泥后矿物质之间的反应受燃烧温度的影响,低温时几乎不反应,温度升高后各矿物质间相互反应生成新的矿物质。