氟塑钢复合管冲蚀磨损性能的试验研究

通过实验研究适用于电厂余热深度回收的新型氟塑钢复合管的冲蚀磨损性能,主要考察在刚玉砂和煤灰两种颗粒冲蚀下,气流速度、温度与颗粒质量浓度等对复合管中低速气流冲蚀磨损的影响.通过扫描电子显微镜对冲蚀磨损后的表面微观形貌进行观察,初步探讨冲蚀磨损机制.结果表明,在中低速度下,复合管的冲蚀磨损速率随气流速度的变化呈幂函数关系;在两种不同颗粒的冲蚀下,复合管的冲蚀磨损速率随颗粒质量浓度的变化均近似呈线性关系;复合管的冲蚀磨损速率随气流温度的升高而降低,但变化幅度不大;微观形貌分析显示,复合管表面受到颗粒反复垂直冲击时主要发生塑性变形,局部出现显微裂纹,在受到颗粒的反复斜向冲击时主要发生切削和犁耕.     

Erosive Wear Study of PPLSF/Glass Fiber ReinforcedHybrid Laminates

This work is focused to examine the erosive performance of hybrid Palmyra palm leaf stalk fiber (PPLSF)/glass polyester laminate against solid particle bombardment. A hand lay-up method was adopted for the fabricating four piles of five distinct laminates with different stacking order glass and PPLSF layers. Amongst them, one group of pure PPLSF and pure E-glass laminates were fabricated. The hybrid laminates were exposed to high speed stream of solid sand particle at three distinct impact velocities (48, 70 and 82 m/s) and four different angles of impingement (30°, 45°, 60° and 90°). The effect of particle velocity, angle of impingement and stacking order on both wear rate and efficiency were highlighted. The experimental assessment reveals a significant improvement in erosive wear resistance properties due to hybridization of PPLSF with E-glass. Again, the laminates with PPLSF layer as skin and glass as core layer exhibited better erosive wear resistance properties than other types of laminates. Further, a maximum value of erosion at lower velocity (48 m/s) is also noticed at 45° impingement angle. However, at high velocity of impact 70 m/s and 82 m/s, the maximum rate of erosion has been shifted from 45° impact angle to 60° impact angle. The alternation of this semi-ductile character to semi-brittle character is evidenced by analyzing the experimental data. Further to justify the mode of erosion, the eroded surface samples were inspected by scanning electron microscope (SEM).     

Shell煤气化飞灰粘附特性影响因素探讨

针对Shell粉煤气化炉飞灰的粘附特性,利用XRF、激光粒度分析仪、SEM-EDX等仪器对采自皖北、云南矿区的两种煤在Shell气化过程中形成的飞灰样品进行了分析检测,探讨了化学成分、粒度分布、表面形貌及元素组成等因素对飞灰粘附特性的影响。结果表明,皖北煤飞灰中一些微量元素含量比云南煤飞灰含量高,颗粒直径在1-2μm范围的大颗粒数明显少于云南煤飞灰,但是飞灰的比表面积大于云南煤飞灰,这是皖北煤飞灰的粘附性比云南煤要高的主要原因;此外,飞灰颗粒为球状,表面附着小的球形颗粒,该颗粒的Ca元素含量较高,使得它们彼此容易粘连在一起,从而促进了飞灰的粘附和沉积。     

Adsorption of superplasticizers in fly ash blended cement pastes and its rheological effects

The adsorption of superplasticizers in fly ash blended cement paste and its rheological effects were investigated.It is shown that the absorption of superplasticizer on portland cement particles is very different from that on fly ash particles.The fly ash particles have smooth surfaces and are negatively charged,so its adsorption capacity is weaker than the portland cement particles.The amount of adsorbed SP in the fly ash blended cement paste depends highly on the replacement proportion of portland cement with fly ash,and to a much less extent on the nature of the fly ash.However,the amount of adsorbed superplasticizer does not correspond well the ζ-potential of the solid particles,due the strong adsorbing capacities of the Portland cement particles.When fly ash replaces portland cement in the paste,the rheological behavior is radically changed,which is closely related to the fineness and density of the ash.The packing and agglomeration of the solid particles are the controlling factors on the rheological parameters of the fresh paste,instead of the amount and type of adsorbed superplasticizer.     

Microstructures and thermal properties of municipal solid waste incineration fly ash

To analyze the feasibility of utilization of thermal technology in fly ash treatment, thermal properties and microstructures of municipal solid waste incineration (MSWI) fly ash were studied by measuring the chemical element composition, specific surface area, pore sizes, functional groups, TEM image, mineralogy and DSC-TG curves of raw and sintered fly ash specimens. The results show that MSWI fly ash particles mostly have irregular shapes and non-typical pore structure, and the supersonic treatment improves the pore structure; MSWI fly ash consists of such crystals as SiO₂, CaSO₄ and silica-aluminates, and some soluble salts like KCl and NaCl. During the sintering process, mineralogy changes largely and novel solid solutions are produced gradually with the rise of temperature. Therefore, the utilization of a proper thermal technology not only destructs those persistent organic toxicants but also stabilizes hazardous heavy metals in MSWI fly ash.     

大掺量粉煤灰水泥研究及其在工程中的应用

利用正交试验和作图方法．分析不同因素对大掺量粉煤灰水泥强度的影响．找出大掺量粉煤灰水泥的优化配合比．结果表明，在42．5普通硅酸盐水泥中掺入≥50％粉煤灰，化学外加剂和矿物掺合料分别为1％和596时。水泥各项技术性能都达到GB1344—1999标准32．5强度等级的要求．本文还介绍了该水泥在土木工程中的应用情况。     

湿排粉煤灰对混凝土性能的影响

通过实验室模拟研究不同湿法存放时间（1～60个月）的2种低钙粉煤灰的形貌、粒径和用于混凝土掺合料的性能变化。粉煤灰湿排后颗粒变粗,颗粒表面出现侵蚀,但颗粒形貌基本保持不变;湿排粉煤灰矿物减水效应明显降低,掺量为20％～40％的湿排粉煤灰混凝土坍落度比原状粉煤灰混凝土减少约20～40mm;掺加湿排粉煤灰的混凝土与外加剂适应性、抗渗和抗碳化无明显变化,坍落度经时损失有所降低;湿法存放3个月的粉煤灰掺量20％时混凝土28d和56d抗压强度比原状粉煤灰混凝土分别下降5．8％和3．7％,但掺量为20％的湿法存放36个月粉煤灰混凝土抗压强度比仍可以达到85％,湿法存放时间为3a和5a的粉煤灰混凝土强度无明显差别。研究结果表明,湿排低钙粉煤灰可以用作为混凝土掺合料。     

流化床燃烧中煤含灰量对灰渣形成特性的影响

为了研究煤颗粒灰质量分数对煤在流化床燃烧过程中灰渣形成特性的影响,在一台小型流化床反应炉上进行煤的灰质量分数对灰渣形成特性的实验.按煤颗粒的灰质量分数,把义马烟煤分为6个颗粒组,并选用各颗粒组的3个粒径范围的煤颗粒进行燃烧实验,研究煤颗粒的灰质量分数对底渣质量分数、底渣与飞灰中的碳量质量分数和粒径分布的影响.结果表明,随着煤颗粒灰质量分数的增加,燃烧形成的底渣质量分数增加,而煤颗粒的燃尽率和飞灰中的碳质量分数都降低.在粒径和燃烧时间相同的条件下,随着颗粒灰质量分数的增加,底渣中留在本粒径档的颗粒质量分数明显增加,而细颗粒的质量分数明显减少.而颗粒灰质量分数对飞灰的粒径分布没有明显的影响.     

Physicochemical properties and heavy metals leachability of fly ash from coal-fired power plant

The physicochemical properties of fly ash from two kinds of coal-fired power plants were studied. Three aspects were examined: the micro-morphology, the mineral composition and the content of heavy metals. The results show that the fly ash from plants using a circulating fluidized bed are more irregular particles, while the particles from the plants using a pulverized coal-fired boiler are mainly spherical in shape. Quartz and mullite are the main crystalline phases in the ash. Clearly, both the technology and the coal used by a power plant can influence the mineral composition of the ash. The mineral composition of fly ash from a circulating fluidized bed is more complex than that from a pulverized coal-fired boiler. The quantity of elements found in the fly ash is greater than that found in the bottom ash for the same plant. Heavy metals are likely to be enriched in the fly ash. Heavy metal leachability was studied using two leaching methods. The results indicate that most of the heavy metals that leached during either batch leaching or column leaching experiments did not exceed the related maximum concentration standards. But Ni concentrations in the leachates from both batch and column tests exceed the standard. The highest excess rates in both tests were 572% and 497%, which levels might threaten the environment.     

Preparation of new cementitious system using fly ash and dehydrated autoclaved aerated concrete

We experimentally studied the interaction between pozzolanic material(fly ash) and dehydrated autoclaved aerated concrete(DAAC). The DAAC powder was obtained by grinding aerated concrete waste to particles fi ner than 75μm and was then heated to temperatures up to 900 ℃. New cementitious material was prepared by proportioning fly ash and DAAC, named as AF. X-ray diffraction(XRD) was employed to identify the crystalline phases of DAAC before and after rehydration. The hydration process of AF was analyzed by the heat of hydration and non-evaporable water content(Wn). The experimental results show that the highest reactivity of DAAC can be obtained by calcining the powder at 700 ℃ and the dehydrated products are mainly β-C2 S and CaO. The cumulative heat of hydration and Wn was found to be strongly dependent on the replacement level of fl y ash, increasing the replacement level of fl y ash lowered them in AF. The strength contribution rates on pozzolanic effect of fl y ash in AF are always negative, showing a contrary tendency of that of cement-fl y ash system.     

粉煤灰去除水中活性紫KN-B

以稀盐酸对燃煤电厂粉煤灰进行活化，实验了粉煤灰和活化粉煤灰对水中染料活性紫KN B的吸附脱色效果．实验结果表明：粉煤灰经活化后对染料的吸附能力明显增强．活化粉煤灰对染料活性紫KN B具有明显的脱色效果．在足量投加量下，废水脱色率可达99%以上；最佳pH值范围为2～8，最佳反应时间为15?min．粉煤灰和活化粉煤灰对水中活性紫KN B的吸附符合Langmuir吸附等温方程．活化粉煤灰用于实际印染工业废水处理，脱色率和COD去除率同样较高     

粉煤灰去除水中活性紫KN—B

以稀盐酸对燃煤电厂粉煤灰进行活化，实验了粉煤灰和活化粉煤灰对水中染料活性紫KN—B的吸附脱色效果．实验结果表明：粉煤灰经活化后对染料的吸附能力明显增强．活化粉煤灰对染料活性紫KN—B具有明显的脱色效果．在足量投加量下，废水脱色率可达99％以上；最佳pH值范围为2～8，最佳反应时间为15min．粉煤灰和活化粉煤灰对水中活性紫KN—B的吸附符合Langmuir吸附等温方程．活化粉煤灰用于实际印染工业废水处理，脱色率和COD去除率同样较高．     

π型管液固两相冲刷腐蚀数值模拟

输油管道系统常常会发生冲刷腐蚀现象,冲刷腐蚀现象产生的主要原因是颗粒对壁面的撞击。使用DPM模型研究固体颗粒对管壁的冲蚀作用,分析π型管的流动特性,研究流体速度、颗粒质量流量、颗粒直径以及颗粒密度对管道冲刷腐蚀速率的影响。模拟结果表明,π型管道在弯头处冲刷腐蚀最严重;当流体速度增大、颗粒质量流量增多时,最大冲刷腐蚀速率增大;当颗粒直径和密度增大时,冲刷腐蚀效果削弱。     

超细粉煤灰及其特性研究

采用ＦＪＭ６８０气流度对粉煤灰进行超细粉磨，磨细至重量中位径分别为２．２７、１．３０、０．９６和０．５９ｍ。用ＳＥＭ对原状灰、普通粉磨、超细粉磨的颗粒形次进行观察，用分数维Ｄｆ对颗粒形貌进行定量描述。另外研究了超细灰的物理、化学性能，结果表明：粉磨细度越细，Ｄｆ值越大，可溶硅量越多，２８ｄ抗压强度比起大，其中重量中位径为０．５９ｍ的超细粉煤灰具有很高的火山灰活性，可望用来配制高强砼。另外Ｄｆ与磨细灰的需水量比有一定的相关性。     

粉煤灰在皂素废水处理中的应用

通过分析粉煤灰在不同的投加量、pH值和反应温度下,对皂素废水处理前后的COD和色度变化,得出粉煤灰处理皂素废水的最大COD去除率可达56．35％,此时的投加量为10g/L,pH值为7,反应温度为20℃。表明粉煤灰处理皂素废水能够达到一定效果,在生产生活中可以广泛应用。     

粉煤灰和矿渣不同配合比对无水泥砂浆性能的影响

以粉煤灰、矿渣等工业废料作为胶凝材料,研究了其不同配合比对无水泥砂浆力学性能的影响.试验结果表明：①随粉煤灰掺和率的增加砂浆的流动性呈逐步上升趋势,当粉煤灰掺和率为70%时,流动性达到普通硅酸盐水泥砂浆（OPC）的水平;②砂浆的表观密度均明显高于OPC,但随着粉煤灰掺和率的增加呈逐步下降的趋势;③随着粉煤灰掺和率的逐步增加,砂浆的强度总体呈下降趋势,掺和率为20%时强度值最大,为OPC的90%,但随龄期的增长强度总体有了稳步提高;④在本试验中,当胶凝体中同时掺和20%的粉煤灰和80%的矿渣时为最佳组合.     

粉煤灰处理含磷废水的研究

以粉煤灰为吸附剂,应用于去除废水中的磷,探讨了吸附时间、吸附荆用量、磷酸盐初始浓度对吸附效率的影响.并对粉煤灰用不同浓度的硫酸进行了改性,改性后的粉煤灰对磷酸盐的去除率大幅度提高,达90%以上.     

飞灰冲刷角度变化对锅炉常用钢材磨损影响的试验研究

在试验研究和理论分析的基础上,本文定义了一个无固次角度系数,并用于定量反映塑性材料的冲蚀磨损率随飞灰冲刷角度变化的规律,同时建立了无因次角度系数计算式,可供工程实际应用.     

高能球磨处理粉煤灰的形貌特征及水化特性

研究了粉煤灰的显微结构,采用高能球磨技术处理粉煤灰,通过扫描电镜和透气法研究了处理后的煤粉灰的结构变化及比表面积变化。结果表明,球磨处理后的粉煤灰极度细化,大颗粒硬质玻珠被打破并无规则化,比表面积增大。热分析结果表明,球磨后的粉煤灰水化放热量缓增,强度实验表明,球磨５ｈ后,配制的粉煤灰水泥强度提高４倍。     

盐碱溶液对混凝土氯离子渗透性能的影响

基于盐碱寒冷地区的工程环境与混凝土的配制特点,模拟配制了SA溶液,对水灰比、含气量和粉煤灰掺量三个参数对混凝土氯离子渗透性能的影响进行了正交试验研究.结果表明:氯离子渗透深度x与渗透时间t之间的关系可以拟合成幂函数x=atb来描述,且在显著性水平α=0.01下其相关关系显著;SA溶液中SO42-和Mg2+的存在对于Cl-的渗透具有一定的抑制作用,冻融循环在混凝土本体结构未破坏之前对于氯离子的渗透也具有一定的抑制作用;水灰比、含气量和粉煤灰掺量三个参数对浸于4.0%NaCl溶液、SA溶液、SA溶液并受冻融循环三种情况下氯离子渗透深度影响的顺序不同;随着水灰比的增大,氯离子渗透深度增大;粉煤灰能够抑制氯离子的渗透,且20%掺量的效果优于35%;含气量对于抵抗氯离子渗透存在不利影响,且未受冻融作用时,3.0%的影响更大.