双级等推力油缸CAT分析

由于油缸长度有时受到空间尺寸的限制,故有多级油缸的产生。目前的多级油缸不能保证在整个推进行程内使推力保持不变,而有些生产设备又有此要求,所以有双级等推力油缸的出现。笔者论述了这一新型油缸的数学模型,给出了计算框图,并对计算结果作了分析。指出在系统压力不变的情况下,油缸推进时,其输出推力在整个行程中确实为一定值,阀的液阻系数是影响油缸工作性能的一个重要参数,面积比值是影响回程速度和拉力变化的最主要因素,并提出了解决这些问题的意见。     

高压旋喷注浆技术在地基补强工程中的应用

本文详细介绍了高压旋喷注浆在某一软弱地基补强工程中的应用,包括地质条件、地基补强原因分析、旋喷桩的设计计算,施工与质量检查等。旋喷注浆技术用于软弱地层加固可以在不停止生产、使用和不破坏建筑物上部结构的条件下,达到加固的目的,且具有施工简单、速度快等优点。     

单向摆喷注浆加固地基技术

高压摆喷注浆是在高压旋喷、定喷注浆的基础上发展起来的一项新技术。通过调研、实验室试验和现场试验，提出了单向摆喷注浆中一些喷射多数和新的观点。采用上述试验与研究分析的一些喷射参数，应用到大同矿务局一扇风机房基础加固工程实践中，达到了预期的加固基础的良好效果。     

ANALYSIS AND DESIGN OF PIT EXCAVATION

ＡＮＡＬＹＳＩＳ ＡＮＤ ＤＥＳＩＧＮ ＯＦ ＰＩＴ ＥＸＣＡＶＡＴ１ＯＮ ＨｏｕＸｕｅｙｕａｎ，Ｌｉｕ Ｑｉａｎｘｉ ＴｏｎｇｊｉＵｎｉｖｅｒｓｉｔｙ，Ｓｈａｎｇｈａｉ２０００９２，ＣｈｉｎａＡＮＡＬＹＳＩＳＡＮＤＤＥＳＩＧＮＯＦＰＩＴＥＸＣＡＶＡＴ１ＯＮ...     

矿用空气压缩机常见故障分析与监测

矿用空气压缩机在运行过程中经常会出现润滑系统和冷却系统故障、系统压力不正常及气阀故障等情况,提出了以PLC为下位机、以组态软件为开发工具的PC机作为上位机的自动监测系统。效果良好。     

高压差越孔密封技术

油田井下滑套类工具普遍存在高压差下越孔密封的技术难题.为了保证滑套能够反复越孔后仍能可靠密封,分析了压力平衡式、双密封圈组合式和异形密封圈3种越孔密封技术的结构和特点,并进行了试验研究.结果表明,这3种技术满足从一次性越孔密封到长期频繁越孔密封的不同要求,基本满足当前油田井下工具对高压差越孔密封的需要.其中压力平衡式越孔密封技术满足长期频繁越孔密封的要求,双密封圈组合式越孔密封技术满足密封次数少于5次的密封要求,而异形密封圈越孔密封技术适用于要求一次性高压差越孔密封的场合.     

减压阀静态密封的故障研究

本文概述了减压阀存在的静密封问题,分析了渗漏的机理,并提出了改进方案.通过提高密封表面的质量、增加O型圈的直径等措施,解决了渗漏问题.     

空气渗透计算中风压与热压的叠加问题

分析了风压和热压共同作用时空气渗透的物理过程,据以指出了现行暖通规范推荐计算方法中的物理概念问题,计算了规范方法的误差,给出了更为合理的计算方法。     

ASTEC application to in-vessel corium retention

This paper summarizes the work done in the SARNET European Network of Excellence on Severe Accidents (6th Framework Programme of the European Commission) on the capability of the ASTEC code to simulate in-vessel corium retention (IVR). This code, jointly developed by the French Institut de Radioprotection et de Sûreté Nucléaire (IRSN) and the German Gesellschaft für Anlagen und Reaktorsicherheit mbH (GRS) for simulation of severe accidents, is now considered as the European reference simulation tool.First, the DIVA module of ASTEC code is briefly introduced. This module treats the core degradation and corium thermal behaviour, when relocated in the reactor lower head. Former ASTEC V1.2 version assumed a predefined stratified molten pool configuration with a metallic layer on the top of the volumetrically heated oxide pool. In order to reflect the results of the MASCA project, improved models that enable modelling of more general corium pool configurations were implemented by the CEA (France) into the DIVA module of the ASTEC V1.3 code.In parallel, the CEA was working on ASTEC modelling of the external reactor vessel cooling (ERVC). The capability of the ASTEC CESAR circuit thermal-hydraulics to simulate the ERVC was tested. The conclusions were that the CESAR module is capable of simulating this system although some numerical and physical instabilities can occur. Developments were then made on the coupling between both DIVA and CESAR modules in close collaboration with IRSN. In specific conditions, code oscillations remain and an analysis was made to reduce the numerical part of these oscillations. A comparison of CESAR results of the SULTAN experiments (CEA) showed an agreement on the pressure differences.The ASTEC V1.2 code version was applied to IVR simulation for VVER-440/V213 reactors assuming defined corium mass, composition and decay heat. The external cooling of reactor wall was simulated by applying imposed coolant temperature and heat transfer coefficient (HTC). The obtained results (pool temperatures, heat flux distribution, reactor wall ablation) were compared with available predictions of other codes. The agreement was correct, in particular on the shape and depth of ablation, as well as the maximum heat flux in case of a thick metallic layer, while ASTEC calculated a lower maximum heat flux for a thin metallic layer.     

Two types of a passive safety containment for a near future BWR with active and passive safety systems

The paper presents two types of a passive safety containment for a near future BWR. They are named Mark S and Mark X containment. One of their common merits is very low peak pressure at severe accidents without venting the containment atmosphere to the environment. The PCV pressure can be moderated within the design pressure. Another merit is the capability to submerge the PCV and the RPV above the core level. The third merit is robustness against external events such as a large commercial airplane crash. Both the containments have a passive cooling core catcher that has radial cooling channels. The Mark S containment is made of reinforced concrete and applicable to a large power BWR up to 1830 MWe. The Mark X containment has the steel secondary containment and can be cooled by natural circulation of outside air. It can accommodate a medium power BWR up to 1380 MWe. In both cases the plants have active and passive safety systems constituting in-depth hybrid safety (IDHS). The IDHS provides not only hardware diversity between active and passive safety systems but also more importantly diversity of the ultimate heat sinks between the atmosphere and the sea water. Although the plant concept discussed in the paper uses well-established technology, plant performance including economy is innovatively and evolutionally improved. Nothing is new in the hardware but everything is new in the performance.