浅议控制铝电解槽炉底结壳的节能效果

本介绍了中国铝业河南分公司电解厂槽型由75kA预焙槽改造为85kA中间点式下料预焙槽后，在应用“四低一高”工艺技术条件管理电解槽生产过程中，电解槽炉底时有结壳的生成，严重影响了电解槽的平稳生产，使能耗和物耗增加，直流电耗大幅升高，电流效率降低。本详细分析了炉底结壳形成的原因，并提出了处理炉底结壳的对策。通过采取预防处理措施后，杜绝了电解槽炉底结壳的生成，取得了电流效率提高2％、吨铝直流电耗降低300kWh的成果，取得了显的增产节能效果。     

Reduction of alternating current loss in a high-TC superconducting transmission cable by means of helical pitch adjustment

We have reported that the alternating current (ac) losses in a 66 kV_rms 3-core high-T_C superconducting (HTS) transmission cable fabricated by Tokyo Electric Power Company and Sumitomo Electric Industries Ltd. are calculated correctly by using an electric-circuit model. According to the calculated results, the circumferential field losses are dominant in the total ac losses in compared with the self-field losses and the axial-field losses. The helical pitches of each layer in the HTS cable are designed to obtain almost same layer currents, which gives the minimum self-field losses. We think that the optimum helical pitches giving the minimum total losses are different from the helical pitches designed by the companies and calculate the optimum values in the condition of the same helical direction of each layer in the cable. As a result, for example, it is found that the ac loss of 2.1 W m⁻¹ cc⁻¹ at transporting 1 kA_rms can be reduced to 1.8 W m⁻¹ cc⁻¹ (about 14% reductions) after redesigning the cable with the optimum helical pitches. The optimum helical pitches are obtained for each given transport current. After redesigning, the distribution of layer currents is not uniform and the circumferential fields are reduced.     

Design and performance of compensator for decremental persistent current in HTS magnets using linear type magnetic flux pump

This paper has described the characteristics of a stationary linear type magnetic flux pump newly developed this time. The linear type flux pump aims to compensate a little decremental persistent current of the HTS magnet in NMR and MRI systems. The flux pump mainly consists of DC bias coil, 3-phase AC coil and Nb foil. Analytical results by the FEM are proved to nearly agree with experimental ones. In the experiment, it has been investigated that the flux pump can effectively charge the current in the load coil of 1.3 mH for various frequencies in 150 s under two following conditions: (1) DC bias of 10 A and AC of 4 A_rms, (2) DC bias of 10 A and AC of 5 A_rms. The maximum magnitudes of initial increasing rate of pumping current and load magnet voltage are: (1) 0.2 A/s and 25 mV and (2) 0.22 A/s and 34 mV, respectively.     

240MVA/220kV双绕组升压变压器工艺系数分析

对几台240MVA/220kV双绕组升压变压器的空载损耗、空载电流和短路阻抗这几个重要参数的试验数据和设计计算值进行了比较与分析,得出了这些参数的一些经验系数.     

电流互感器特性对母差保护动作可靠性的影响及改进措施

通过实际试验数据及理论分析，阐述了变电站电流互感器特性对相比式母线差动保护动作性能的影响，尤其是中间变流器特性和开关电流互感器的配合问题，以便于分析变电站同类型的母差保护动作的可靠性。     

涡流技术在列管检测中的应用

对列管式反应器进行了现场涡流检测,实践表明,涡流检测速度快、灵敏度高,测试结果准确.证实了根据阻抗图幅度和相位分析判定缺陷技术优点.     

涡流检测中探头运动速度对检测信号的影响分析

主要从理论和实验两个方面对涡流检测时的探头运动速度对检测信号的影响进行了分析和研究,研究的结果对实际的检测具有很重要的指导意义.     

道路运输统计实际操作方法的探讨

本文阐述新形势下道路运输统计工作的基本现状，存在的问题，道路运输统计工作的重要性；做好道路运输统计工作的基本要求，如何加强道路运输统计的基础工作，提高统计数据质量，如何准确反映道路客货运输发展状况都作了说明；并对道路客货运输统计的统计指标进行了研究。     

阶梯式预制混凝土坝设计

结合穆棱市穆兴渠首工程的实例，介绍了一种拦河坝型——阶梯式预制混凝土坝。从设计上节省了消能长度，从施工上缩短了工期。经过10a的运用观察，该项技术是经济实用的。     

客车蒙皮组焊件焊接工艺的改进

针对西安某汽车厂客车蒙皮组焊件焊接采用CO2气体保护焊生产率低、焊接变形大、表面处理难度大、质量难以保证的问题，本文作者对其进行了工艺改进，通过采用全自动缝焊焊接工艺及选择合理的工艺规范参数，在保证结构和强度的前提下，使蒙皮组焊件焊接表面质量大幅提高，劳动强度大幅下降，生产率提高数倍。