温度、接触压力与时间对燃煤飞灰固体桥力的影响规律

在所开发的用于在高温条件下(最高使用温度可达1600℃)测量灰的固体桥力的实验系统上,研究了温度、接触压力及接触时间对燃煤飞灰的固体桥力的影响规律。结果显示,燃煤飞灰的脖颈抗拉强度与温度之间呈现出双峰分布曲线的关系。这是由于随着温度的变化,燃煤飞灰的物相状态发生改变,玻璃体成分的含量也随之变化。在温度不变的情况下,燃煤飞灰的烧结脖颈抗拉强度随接触时间和接触压力的增加而增大。     

单颗粒黏结行为的实验研究

实验研究了固体桥力作用下的颗粒黏结脖颈成长及抗拉强度变化规律。通过颗粒黏结的动态观测,发现烧结理论能很好地解释脖颈的成长过程,接触时间对脖颈影响相对较小,黏结温度影响较大;通过测量温度场中的脖颈抗拉强度,发现黏结温度升高,抗拉强度先增后减,液相出现后抗拉强度迅速下降;黏结时间增长,抗拉强度逐渐增大,并趋向于一个稳定值;接触压力增大,抗拉强度也随着增大。研究还证实了脖颈抗拉强度低于同温度下的材料强度,脖颈存在晶格缺陷。量纲1脖颈强度在温度低于0.8T_melt时变化幅度很小,小于材料强度的0.1倍;在高于0.8T_melt后,量纲1脖颈抗拉强度会迅速增大,直至逼近材料自身的强度。     

采用更加黏着性测试方法

橡胶的黏着性对轮胎性能影响十分重要。在实验室中设计了实验测试橡胶的黏着性,对于黏着性的3个关键影响因素:接触压力、材料温度和试样接触时间做了研究分析。对橡胶黏着性从峰值力和总能量两个方面进行了测试。     

1000MW燃煤机组负荷变化对飞灰特性的影响

燃煤机组变负荷调峰运行是提高可再生能源消纳能力的重要举措，但会对燃烧过程及系统产生重要影响。飞灰特性与锅炉结渣、除尘设备性能、颗粒物排放等密切相关，笔者研究了燃煤锅炉负荷变化对飞灰特性的影响规律，用于指导炉膛沾污结渣和颗粒物排放等相关问题的防控。针对1 000 MW燃煤锅炉，在60%和90%运行负荷下分别采集飞灰样品，利用先进的计算机自动控制扫描电镜(CCSEM)技术对飞灰化学和矿物成分、粒径分布以及形状特征进行深入表征，采用数字成像煤灰熔点分析仪对飞灰熔融温度进行分析，揭示了锅炉运行负荷变化对飞灰特性和熔融行为的影响。研究结果表明锅炉在不同运行负荷条件下飞灰化学成分相似。无机矿物元素交互作用是影响飞灰粒径分布的关键因素，低负荷运行工况下煤中含Ca和Fe的矿物与硅铝酸盐交互反应减弱，飞灰整体粒径分布向小粒径迁移，飞灰的D₅₀(小于该粒径的颗粒占50%)由约40μm减至约30μm。相比高负荷运行工况，低负荷运行工况下飞灰在炉膛中的熔融受抑制，熔融飞灰比例相比高负荷运行工况降低约10%,低负荷运行条件下燃烧温度降低是导致飞灰熔融比例降低的主要原因。     

贫煤气废气的综合利用

燃煤锅炉掺烧贫煤气,可以减少燃煤的用量,降低了飞灰中碳量和烟气中氧含量,固体未完全燃烧损失所占的百分数和灰渣热损失下降,锅炉热效率提高,年创效益可达百万元。     

火力发电厂燃煤飞灰润湿性能

化学团聚是控制燃煤电厂细微颗粒排放最有效的方法之一。颗粒物被团聚剂润湿是化学团聚的首要步骤。以小龙潭电厂燃煤飞灰为对象,采用激光粒度仪研究了燃煤飞灰在十二烷基硫酸钠(SDS)、十二烷基苯磺酸钠(SDBS)和Triton X 100(TX100)三种润湿剂溶液中的润湿性能,考察了润湿剂浓度、温度对燃煤飞灰润湿性能的影响。结果表明：水仅能将飞灰颗粒中的PM^₁₀+部分全部润湿,0.25%的SDS溶液中PM_2.5⁺可全部润湿,1%的SDS及0.4%的SDBS溶液中PM₁⁺可全部润湿;TX100溶液在低浓度条件下具有较强的润湿飞灰颗粒的能力,且0.1%的TX100溶液对细微颗粒的润湿性能较好;温度从20℃上升到60℃,润湿剂溶液表面张力降低,飞灰的润湿性能增强。鉴于飞灰在三种润湿剂中良好的润湿性能,三种润湿剂均可作为团聚剂组分以促进燃煤飞灰中的细微颗粒润湿进而被团聚成为容易脱除的大颗粒。     

燃煤飞灰氯化浸出提取锗的研究

采用富含锗的煤提取四氯化锗,燃煤飞灰的氯化浸出过程是提取锗的主要工序之一。对燃煤飞灰的氯化浸出过程的原理进行分析和研究,提出合理的浸取盐酸浓度、提取温度等工艺指标,提高锗的浸出率。     

煤粉炉掺烧生活垃圾对灰渣特性的影响研究

利用小试规模煤粉炉,研究掺烧不同比例生活垃圾对燃煤灰渣特性的影响,主要包括飞灰元素组成、飞灰粒径分布、飞灰形貌、灰熔点和结渣特性等影响变化研究。结果表明,随着生活垃圾掺烧比例的增加,灰分中Ca、Fe、Cl和S元素含量增加,Al、Mg、K、Na、Ti和Si含量降低,飞灰球形颗粒分布减少,层状堆积结构增多;灰渣熔融特征温度呈平缓下降趋势,但变化范围小于2%,影响较小;掺烧量为25%时,飞灰表面发现少量褐色大颗粒。总之,生活垃圾掺烧对燃煤灰渣特性影响很小,该结果为实际煤粉炉开展掺烧生活垃圾试验提供了一定理论基础。     

煤粉炉掺烧生活垃圾对灰渣特性的影响研究

利用小试规模煤粉炉,研究掺烧不同比例生活垃圾对燃煤灰渣特性的影响,主要包括飞灰元素组成、飞灰粒径分布、飞灰形貌、灰熔点和结渣特性等影响变化研究。结果表明,随着生活垃圾掺烧比例的增加,灰分中Ca、Fe、Cl和S元素含量增加,Al、Mg、K、Na、Ti和Si含量降低,飞灰球形颗粒分布减少,层状堆积结构增多;灰渣熔融特征温度呈平缓下降趋势,但变化范围小于2%,影响较小;掺烧量为25%时,飞灰表面发现少量褐色大颗粒。总之,生活垃圾掺烧对燃煤灰渣特性影响很小,该结果为实际煤粉炉开展掺烧生活垃圾试验提供了一定理论基础。     

石墨/酚醛树脂复合板与碳纸间接触电阻

应用模压工艺制备了质子交换膜燃料电池（PEMFC）用石墨/酚醛树脂（PF）复合板.通过四电极法测量了复合板与碳纸间的接触电阻.考察了接触压力、PF树脂含量及模压工艺条件对接触电阻的影响.结果表明,接触压力和PF树脂含量是对接触电阻有较大程度影响的两个重要因素.接触压力的增大导致接触电阻迅速减小,而随着PF树脂含量的增加,接触电阻有着非常快的增加趋势.模压压力对接触电阻已有一定程度的影响,但其影响幅度不如接触压力和树脂含量那么大.随着模压压力的增大,接触电阻的增加趋势比较缓慢.模压时间和模压温度对接触电阻基本没有影响.     

聚氨酯嵌缝材料老化性能初探

为探讨嵌缝材料老化机理及评价指标,选择几种低模量聚氨酯嵌缝材料,研究了嵌缝材料的耐热、耐碱、耐水和耐紫外线老化性能。结果表明,热老化后的材料拉伸强度和拉伸粘结强度明显增大,最高分别增加了156%和117%;材料的耐碱性能较好,碱处理后拉伸性能基本保持不变,但是浸水后粘结性能下降,拉伸粘结强度最高下降了47%;紫外线照射加速了嵌缝材料的老化,表现为材料起皮、龟裂和开裂。提出了增加热老化后拉伸强度上限值和紫外老化后外观来评价嵌缝材料老化性能的建议。     

Synthesis and characterization of waterborne polyurethane adhesives containing different amount of ionic groups (I)

A series of waterborne polyurethanes (WBPU) containing different amount of 2,2‐bis(hydroxymethyl) propionic acid (DMPA) were synthesized using prepolymer mixing process. Relationships between the DMPA content and physical, mechanical, and thermal properties as well as adhesive behavior at different condition were investigated. Stable aqueous dispersions of WBPU were obtained when the DMPA content was more than 10 mol %. At higher DMPA content, the particle size of the WBPU dispersion was lower but the viscosity of the dispersion was higher. Water swelling and tensile strength of the films increased with increasing of DMPA content. The optimum adhesive strength of WBPU adhesives was found to be depended on the DMPA content, pressing temperature, and pressure on adhesion process. The adhesive strength of WBPU adhesives increased with increasing DMPA content. The optimum pressing temperature decreased with increasing DMPA content. The adhesive strength of WBPU adhesives increased with increasing pressure up to 15 kg f/cm² and then leveled off. The optimum pressing temperature of WBPU adhesives samples containing 24.02, 22.05, and 17.05 mol % DMPA was about 100, 120, and 140°C, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5684–5691, 2006     

煤矸石填充聚酰胺6复合材料的结构与性能研究

采用熔融共混法制备了聚酰胺6／煤矸石复合材料，研究了复合材料的力学性能、微观结构、结晶行为和流变性能。结果表明：煤矸石的加入使聚酰胺6的的拉伸强度、弹性模量、弯曲强度和弯曲模量分别增加了约53．8％、66．1％、37．1％和63．4％，而冲击韧性基本保持，煤矸石最佳填充量为25％；煤矸石在聚酰胺6基体中分散均匀，复合材料具有韧性断裂特征；煤矸石使聚酰胺6的结晶温度由187．0℃升高到191．3℃，过冷度由33．6℃降至18．9℃，结晶温度范围变窄，即煤矸石提高了聚酰胺6的结晶速率，对聚酰胺6具有异相成核作用；在所研究的剪切速率范围内，聚酰胺6及其复合材料的流变行为表现为假塑性，煤矸石的加入使非牛顿指数减小，聚酰胺6对剪切敏感性下降。     

高钠煤灰烧结特性研究进展

中国新疆准东煤具有储量巨大、开采成本低、挥发分高、硫含量低等特点,是优质的动力用煤。但准东煤钠含量高,燃烧利用时易在受热面上形成烧结性积灰,产生严重的结渣,极大限制了高钠煤的开发利用。因此,要实现高钠煤的清洁高效利用,需充分认识高钠煤灰的烧结特性。总结了高钠煤积灰结渣机理,概述了高钠煤灰烧结机制,探讨了二者之间的内在关联。高钠煤在燃烧过程中,煤中碱金属(主要为钠)释放并以Na_2SO_4、NaCl及Na的形式存在于烟气中,与受热面接触并于其上冷凝形成黏性内白层,内白层捕获飞灰颗粒后反应生成低熔点化合物,其烧结温度降低,使锅炉受热面上发生沾污增强型的"沾污烧结"过程。高钠煤灰的烧结过程包含固相烧结、液相烧结和气相烧结3种方式,对煤灰烧结过程的影响因素包括反应温度、化学组成、煤灰粒径、反应气氛、添加剂种类、锅炉设计和锅炉运行工况等。其中添加剂按氧化物种类可分为碱性氧化物和酸性氧化物,一般情况下碱性氧化物可以降低煤灰烧结温度,酸性氧化物可提高煤灰烧结温度。未来对于提高高钠煤灰烧结温度的研究方向可从新型添加剂出发,找到既能固定烟气中的钠,又能与灰渣中的低熔点含钠矿物质反应生成高熔点化合物的单一或混合成分的添加剂。同时,关于钠蒸气对积灰结渣在微观层面上的动态特性的影响机制也需进一步研究。概述了煤灰烧结温度的测量方法,热导率分析法、压力测量法、热机械分析法、筛分法和压降法,其中压降法是目前为止测量烧结温度较为准确的方法。介绍了上海理工大学碳基燃料洁净转化实验室在高钠煤灰烧结特性方面的研究方向,以期为解决燃用高钠煤锅炉积灰结渣问题提供参考。     

Sintering characteristics of low-rank coal ashes

The electrical resistance and compressive strength were measured to gain a better understanding of the sintering characteristics of low-rank coal ashes involved in deposit formation in combustion systems. Low-rank coal ashes were prepared by the standard ASTM ashing procedures at 750°C and then separated into three different particle size fractions. The sinter point determined by the electrical resistance method decreased with decreasing particle size at three different particle size fractions of each coal ash. The compressive strength lest was made as a function of temperature in the range 750–950°C. At a given sintering temperature, strength of the sintered ash was inversely proportional to particle size. For any given particle size of each coal ash, the strength increased with increasing sintering temperature. X-ray diffraction of the sintered coal ashes showed that, as sintering temperature increased, there was an inverse relationship between sinter strength and the amount of anhydrite in the sintered ash, and a direct relationship between strength and the amount of hauyne.     

Atmospheric pressure plasma surface modification of titanium for high temperature adhesive bonding

In this investigation surface treatment of titanium is carried out by plasma ion implantation under atmospheric pressure plasma in order to increase the adhesive bond strength. Prior to the plasma treatment, titanium surfaces were mechanically treated by sand blasting. It is observed that the contact angle of de-ionized water decreases with the grit blast treatment time. Optical microscopy and scanning electron microscopic (SEM) analysis of untreated and atmospheric plasma treated titanium are carried out to examine the surface characteristics. A substantial improvement in the surface energy of titanium is observed after the atmospheric pressure plasma treatment. The surface energy increases with increasing exposure time of atmospheric pressure plasma. The optimized time of plasma treatment suggested in this investigation results in maximum adhesive bond strength of the titanium. Unmodified and surface modified titanium sheets by atmospheric pressure plasma were adhesively bonded by high temperature resistant polyimide adhesive. The glass transition temperature of this adhesive is 310 °C and these adhesively bonded joints were cured at high temperature. A substantial improvement in adhesive bond strength was observed after atmospheric pressure plasma treatment.     

材料线膨胀系数对拉伸剪切性能的影响

为了研究被粘接材料的线膨胀系数对胶接件拉伸剪切性能的影响,用改性环氧树脂(EP)胶粘剂粘接不同材料,并对该胶接件进行拉伸剪切强度试验和温度影响试验。研究结果表明,被粘接材料的线膨胀系数不同会导致胶层在热冷变化过程中受到内应力作用而破坏,同时热空气进入胶层会导致胶层氧化变色,致使胶粘剂界面结合强度和胶粘剂自身强度降低;两种被粘接材料的线膨胀系数差异越大,经热冷变化后胶接件的拉伸剪切性能越低;在相同条件下,热冷变化温差越大,胶接件的拉伸剪切性能越低。     

Multilateral approaches for investigation of particle stickiness of coal ash at low temperature fouling conditions

Particle stickiness is a key parameter for increasing ash deposition in gasification process. We conducted multilateral investigations to evaluate particle stickiness of coal ash at low temperature fouling conditions through Watt and Fereday’s viscosity model, dilatometry (DIL) and laser flash apparatus (LFA) technique. Seventeen coals were employed for ash deposition experiments under gasification condition through drop tube furnace (DTF). The low viscosity not only led to increasing ash deposition behavior, but also increasing the particle size of deposited ash. From DIL analysis, the ash sintering behavior increased with increasing temperature due to increase of particle stickiness. The high amount of Fe₂O₃, CaO and MgO components resulted in low sintering temperature and high reduction of physical length. Through LFA analysis, the thermal conductivity increased with increasing temperature, because of increasing particle stickiness. In addition, its value was correlated with the propensity of common fouling indices.     

Effect of Temperature on the Joints Strength of an Automotive Polyurethane Adhesive

In this paper, the performance of an automotive polyurethane adhesive was studied through adhesive joints tests. Butt joints and single lap joints were fabricated and tested at seven temperature measuring points (TMPs). It is shown that both the tensile strength and lap shear strength decrease with the increasing of temperature. Quadratic polynomial expression obtained by the least square method can represent the tensile and lap shear strength as a function of temperature very well. ?40°C, 0°C, and 90°C were selected as the most ideal TMPs for this adhesive through the comparison of the residual sums of squares of 35 fitting curves with different combination of TMPs. Scarf joints with adhesive angles of 60° and 30° were fabricated and tested at ?40°C, 0°C, and 90°C. It also showed a decrease in joint strength with the increasing temperature. Joint strength as a function of adhesive angle is presented. It was found to closely follow a linear behaviour. A three-dimensional surface, consisting of temperature, adhesive angle, and joint strength, is presented finally to facilitate the design of automotive bonding structures.