An Efficient Summer Operation Scheme for a Thermal Power Plant Air Cooling System based on Electric Peak Shaving

We proposed a novel efficient operation scheme for a thermal power plant’s air-cooling system based on peak shaving, in order to cope with high ambient temperature in summer. We introduced an absorptiongeneration equipment with water/lithium working pairs into the air cooled condenser(ACC) to reconstruct the traditional thermal power plant, and established a dynamic thermodynamic model adopting Ebsilon code. We studied the thermodynamic performance variation of the reconstructed thermal power plant throughout a 24-hour cycle and found that the fluctuation ratio of the turbine back pressure decreased to 6% from 78%, which is beneficial for the stable and safe operation of the electric power system. The thermal performance improvement benefited from the exploitation of the heat transfer potential of ACC, which realized via cold duty schedule throughout the day, under different ambient temperature conditions. In this system, the generated power was higher at relatively high ambient temperature than that at relatively low ambient temperature, which solved the electricity demand-supply imbalance problem under high ambient temperature. Finally, the same optimization effects for power thermal plants with an indirect air-cooling system were obtained using the same operation scheme.     

Indirect Methods of Detecting and Evaluating Inclusions in Steel A Review

Thenonmetallicinclusionisasignificantprob lemincaststeelsleadingtoexcessivecastingrepairs orrejectedcastings.Inclusionsinsteelandinclu sions relateddefectsinsteelproductshavebeenre viewedelsewhere[1].Measurementtechniquesofin clusionsrangefromdirectmethods,whichareaccu ratebutcostly,toindirectmethods,whicharefast andinexpensive,butareonlyreliableasrelativein dicators.Indirectmethodsincludetotaloxygen measurement,nitrogenpickup,slagcomposition measurement,andsoon.Anextensivereviewon indirectmet…     

Online state-of-health prediction of lithium-ion batteries with limited labeled data

State-of-health (SOH) plays a vital role in battery health management and power system stability. This process can be achieved by capacity estimation. However, in practice, the capacity of a battery is difficult to obtain online given that it cannot be determined with general sensors. This means that the capacity is only known for the limited cycles of the batteries. To address this issue, we propose a novel semi-supervised learning framework to estimate the capacity of unlabeled data to achieve better SOH prediction. First, four indirect features are extracted from the charging profiles. Then an improved locally linear reconstruction method is used to determine the capacity distributions of the unlabeled data. Combined with the oversampling method applied to generate a series of data by the estimated distributions, a support vector regression model is utilized to predict the RUL of the batteries given the threshold values of the batteries. A case study with two types of cellular phone lithium-ion batteries is presented to illustrate the effectiveness of the proposed method for the prediction of the remaining useful life of different batteries and different starting points. The experimental results prove that the performance of the proposed method is better than the K-nearest neighbor method and locally linear reconstruction method in terms of accuracy and robustness.     

间接测量法在盾构隧道模态识别中的应用研究

为了快速、经济且准确地实现盾构隧道的健康监测，将桥梁健康监测的间接测量法应用于盾构隧道结构中，在推导了移动车辆-盾构隧道耦合振动作用下车辆加速度响应解析解的基础上，分析了考虑阻尼影响的盾构隧道振型间接识别方法，从理论上证明了间接测量法在盾构隧道模态识别中应用的可行性。通过实验室试验验证盾构隧道频率间接识别方法，试验结果表明，采用间接测量法与直接测量法测试得到的盾构隧道频率接近，误差为2.8%。同时，通过数值算例验证了基于间接测量法的盾构隧道频率、振型、阻尼比识别方法，并分析车辆速度、车辆阻尼、盾构隧道阻尼等参数对盾构隧道模态间接识别结果的影响。分析结果发现：车速对频率间接识别的影响较小，而过低的车速会导致振型无法识别，应选择5 m/s以上的车速；车辆阻尼大小对振型间接识别的影响较小，而增大车辆阻尼有利于频率间接识别；盾构隧道阻尼的增大不利于频率和振型的间接识别。     

沥青混合料饱水过程的强度演化规律及机理分析EI北大核心CSCD

为研究SBS改性沥青混合料在饱水过程中的力学强度演化过程,提出了一种基于圆孔孔边应力集中效应的力学模型,分别计算了非饱水和饱水孔隙的孔边应力.对不同沥青含量的SBS改性沥青混合料试件进行水敏感性试验(MIST)和恒温浸水试验,采用间接拉伸强度(ITS)和拉伸强度比(TSR)来表征沥青混合料的强度演化过程,分析孔隙水压循环次数、水浴时间、孔隙水压力和温度对沥青混合料强度的影响.结果表明:在劈裂荷载作用下,孔隙水压抗力消散了薄弱孔隙的应力集中;随着孔隙水压循环次数或恒温水浴时间的增加,试件的ITS先减小后增大,TSR持续增大;沥青混合料在饱水过程中的强度增加,实际上采集到的是沥青混合料自身强度与孔隙水压力的加和;温度对沥青混合料强度的影响比孔隙水压力的影响更加显著.     

补强圈与壳体接触特性的有限元分析

采用ANSYS软件的非线性分析方法,模拟分析了补强圈与壳体之间的接触行为。以一个水冷磁体容器开孔补强设计为例,分析补强圈与壳体在不同内压下,接触间隙对接触应力与最大应力的影响;同时采用间接的热-结构耦合分析方法,分析了接触间隙对热应力的影响,并对不同温度下,接触间隙对热应力的影响进行了探讨。     

间接空冷和直接空冷系统技术经济分析

介绍了北方地区发电机组空冷技术的应用情况。通过比较直接空冷和间接空冷的技术特点和投资分析,得出间接空冷系统在运行维护和技术经济性上有着较多优势,如机组运行稳定性及夏季运行安全性均较好,基本无噪音,容易清洗等。采用国产化大型间接空冷系统可提高发电厂运行的经济性。     

隔爆型电气设备的引入结构和引入装置

根据GB3836系列国家标准的要求,结合隔爆型电气设备的特点,介绍了直接引入结构和间接引入结构的要求和使用条件以及引入装置的要求和常用结构,旨在帮助制造厂和用户合理地选择隔爆型电气设备的引入结构和引入装置,保证隔爆型电气设备防爆安全性能。     

国内首例600MW机组间接空冷示范工程及技术

通过对3种形式空冷系统的比较,重点介绍了阳城电厂二期工程2台600MW机组表面凝汽式间接空冷系统的关键技术与创新.该系统可节省水资源、厂用电低、噪声低、布置灵活、防冻措施可靠;采用铝质散热器与表面式凝汽器的间接空冷系统节约投资,运行成本低:空冷塔"X"形支柱首次采用了整体性一次浇筑成型技术.结合机组实际运营技术指标和取得的经济社会效益,论证了表面凝汽式间接空冷机组较其他类型空冷机组的明显优势.该工程的推广应用对空冷系统的设计发展具有深远的影响.     

间接光度法测定丙交酯含量

采用间接光度法测定粗丙交酯中丙交酯的含量,讨论了溶剂类型、胺解反应时间、酸碱用量等因素对测定结果的影响。结果表明,以乙醇为溶剂、加入3 mol/L NaOH甲醇溶液1 mL、胺解反应20 min、中和酸3 mol/L HCl用量为3 mL时,此时吸光值A与丙交酯浓度C的关系为A=0.006 07C-0.054,R=0.999。丙交酯的检测下限为9.2μg/mL,样品的加标回收率为92.03%~104.47%,RSD为4.911%,该方法可用于丙交酯含量的测定。