600 MW超临界汽轮发电机组振动缺陷剖析及处理

分析总结了600MW超临界汽轮发电机组当前较普遍存在的典型振动缺陷．对国华太仓发电有限责任公司7号机组低压Ⅱ转子轴承、励磁机9号轴承轴振偏大等问题进行了分析诊断。通过现场轴系动平衡,多平面同时加重,使各轴承轴振动达到优良水平。     

超临界600 MW机组锅炉起动初期过热器超温的原因及控制

近年投产的东方锅炉厂配套超临界600 MW机组锅炉在点火起动至机组并网初期,存在不同程度的屏式过热器(屏过)超温,并因主蒸汽温度过高导致汽轮机冲转后振动超标,被迫打闸停运等问题.对此,结合多家电厂的运行实践,分析了影响汽温的主要因素,并提出了相应的控制措施.     

国产600 MW汽轮发电机组振动问题分析及治理

国产600 MW汽轮发电机组在运行过程中普遍存在某些振动问题,如低压转子轴承座振动大、高负荷工况高中压转子轴承突发性振动、发电机转子不稳定振动和集电小轴稳定轴承振动大等,严重影响机组的安全、可靠运行.对国产600 MW机组的振动特征和振动原因进行分析,并总结了振动处理过程的有效措施.     

Conductive performances of solid polymer electrolyte films based on PVB/LiClO4 plasticized by PEG200, PEG400 and PEG600

Solid polymer electrolyte (SPE) films consisting of polyvinyl butyral (PVB) as host polymer, LiClO₄ as alkali salt at mole ratio of [O]:[Li] = 8, and different molecular weight polyethylene glycol (PEG) including PEG₂₀₀, PEG₄₀₀, and PEG₆₀₀ as plasticizers are prepared by physical blending method. The dielectric relaxation and electrochemical impedance measurements reveal that the conductive performances are improved by adding PEG as plasticizers through the enhancement in the moving space for ions, and PEG₄₀₀ performs plasticizing effect superior to PEG₂₀₀ and PEG₆₀₀. Their conductivity is measured by using a sandwiched Pt/SPE/Pt cell model. SPE with 30% PEG₄₀₀ (wt%) of PVB exhibits the maximum conductivity at room temperature, and its conductivity increases linearly with temperatures from 303 to 333 K at two to three orders of magnitude higher than that of the other two SPEs containing 30% PEG₂₀₀ and 30% PEG₆₀₀, respectively. However, their conductivity does not increase linearly with the increase in heating temperatures until the temperature reaches around 333 K; the decrease in conductivity with heating from their maxima is attributed to the restriction of ion moving space because of the crosslinking reaction between hydroxyl and aldehyde groups. As observed from the XRD and the microscopy results, PEG₄₀₀ is more effective than others in enhancing the conductive performances of these SPEs through changing LiClO₄ from crystalline to amorphous state, increasing the flexibility of PVB, disturbing the short distance sequential order of PVB chains, and promoting the formation of ‘pathway’ for ions’ movement.     

Enhancing the formation and shear resistance of nitrifying biofilms on membranes by surface modification

Polypropylene (PP) membranes and polyethylene (PE) surfaces were modified to enhance formation and shear resistance of nitrifying biofilms for wastewater treatment applications. A combination of plasma polymerization and wet chemistry was employed to ultimately introduce poly(ethyleneglycol) (PEG) chains with two different functional groups (-PEG-NH₂ and -PEG-CH₃). Biofilm growth experiments using a mixed nitrifying bacterial culture revealed that the specific combination of PEG chains with amino groups resulted in most biofilm formation on both PP and PE samples. Detachment experiments showed similar trends: biofilms on -PEG-NH₂ modified surfaces were much stronger compared to the other modifications and the unmodified reference surfaces. Electrostatic interactions between the protonated amino group and negatively charged bacteria as well as PEG chain density which can affect the surface structure might be possible explanations of the superiority of the -PEG-NH₂ modification. The success of the-PEG-NH₂ modification was independent of the original surface and might, therefore, be used in wastewater treatment bioreactors to improve reactor performance by making biofilm formation more stable and predictable.     

WDB620高强钢应用于大型蜗壳的焊接制造工艺研究

2005年初,水电十四局承担了漫湾二期水电站和小湾水电站蜗壳的制造任务。蜗壳钢材选用国产600 MPa级别高强钢,为了全面综合地考核该级别钢种的材料强度和安全裕度,检验模拟大型蜗壳焊接制造工艺的可靠性。对国产的WDB620高强钢进行了可焊性和制造工艺性试验研究,并在国内首次设计、制造模拟压力容器并对其进行水压试验和爆破试验。研究成果通过中国水电集团公司鉴定,结论为该课题研究成果达到国内选进水平。     

660 MW机组汽轮机真空快速冷却系统的应用

通过对邯峰发电公司660 MW机组汽轮机的结构分析,介绍了其采用的真空法快速冷却(快冷)系统,并将真空法快冷与常用的加热压缩空气法快冷进行了比较。实践证明,真空快冷系统的应用较为安全可靠。     

电压互感器二次中心线接地方式的分析和改进

分析了电压互感器二次回路中心线电压产生漂移的原因，指出了现有的回路在某些特殊故障情况下的隐患，提出了中心线接线的改进方法和建议。     

Polyethylene glycol as an efficient and reusable solvent medium for the synthesis of thiohydantoins using K2CO3 as catalyst

Polyethylene glycol was found to be an inexpensive, non-toxic, recyclable and an effective medium for the synthesis of thiohydantoin derivatives in the presence of K₂CO₃ as the catalyst. The procedure is operationally simple and environmentally benign.     

国内首台600MW对冲燃烧锅炉低NO_x燃烧技术改造

为将锅炉低NOx燃烧技术改造可能产生的负面影响减至最低程度,在燃烧器改造设计中,注重对主燃烧器分级燃烧的设计优化,采用较大的主燃烧区化学当量比,降低对主燃烧区低化学当量比的依赖度和敏感度,同时采取受热面调整和磨煤机增装动态分离器等配套措施。改造后锅炉总体性能良好,NOx减排幅度达到50%。