以外供液氮替代膨胀机的深度冷冻循环

介绍空分制氮装置采用膨胀机循环与液氮循环的两种工艺流程及能量平衡 ,示出了两种循环的实例比较。指出外供液氮可以作为冷源替代膨胀机 ,且单耗低、操作更方便 ,设备维护量更小、氮气提取率更高     

Simulating BPP using a general weak random source

We show how to simulate BPP and approximation algorithms in polynomial time using the output from a -source. A -source is a weak random source that is asked only once forR bits, and must output anR-bit string according to some distribution that places probability no more than 2^–R on any particular string. We also give an application to the unapproximability of MAX CLIQUE.This paper appeared in preliminary form in theProceedings of the 32nd Annual Symposium on Foundations of Computer Science, 1991, pp. 79–89. Most of this research was done while the author was at U.C. Berkeley, and supported by an AT&T Graduate Fellowship, NSF PYI Grant No. CCR-8896202, and NSF Grant No. IRI-8902813. Part of this research was done while the author was at MIT, supported by an NSF Postdoctoral Fellowship, NSF Grant No. 92-12184 CCR, and DARPA Grant No. N00014-92-J-1799. Part of this research was done at UT Austin, where the author was supported by NSF NYI Grant No. CCR-9457799.     

消除膨胀机系统的安全隐患

分析了膨胀机发生抱轴事故的原因,介绍了膨胀机系统存在的安全隐患,并提出了消除隐患的措施,简述了采取措施后的效果     

Integration of a three-stage expander into a CO2 refrigeration system

The inclusion of an expander with work recovery provides two advantages for transcritical CO₂ refrigeration cycles: the COP is improved and the exhaust pressure of the main compressor is lowered. Several designs of expanders have been proposed for this application and some prototypes have been tested already. In our laboratory a three-stage expander has been developed, which replaces the throttle valve of the normal refrigeration cycle and expands into the two-phase region. For optimum integration into the overall system it is proposed to install a vapour-liquid separator between the second and third stage of expansion. The vapour is guided back to the third expander stage whereas the liquid is supplied to the cooling stations via thermostatic or electronic expansion valves.     

空分启动阶段主换热器热端温差过大的原因分析及处理

介绍了空分设备启动阶段主换热器热端温差过大的现象和原因 ,通过计算膨胀机的最大膨胀量 ,得出膨胀量偏大是导致热端温差过大的原因     

直缝埋弧焊钢管扩径头的研制

扩径头是直缝埋弧焊钢管生产线扩径机上的关键部件,一直依赖进口,价格昂贵且交货时间长,研制国产扩径头迫在眉睫。从扩径头的技术难点入手,分析了中直径和大直径扩径头的不同结构形式和润滑方式。在结构设计时,针对扩径头各部件的使用要求,选用不同的工具钢和相应的热处理工艺,确保了扩径头的整体使用寿命。新研制的扩径头投入使用两年来,共扩直缝埋弧焊钢管3万多根,合格率100%,满足了扩径的要求。     

应用于跨临界CO_2压缩循环的双转子滚动活塞式膨胀机的研究

由于二氧化碳制冷系统的制冷效率与人工合成制冷剂相比处于劣势,故采用跨临界循环,并利用膨胀机回收膨胀功以减少膨胀过程的能量损失,达到提高整个循环效率的目的。针对目前膨胀机存在的诸多问题,设计应用于跨临界CO2压缩循环的新型双转子滚动活塞膨胀机。该膨胀机的一级气缸始终与进气管连通,二级气缸始终与排气管相通,随着转子的转动在两气缸之间形成膨胀空间,因此,不需要专门的进气控制装置。对膨胀机的运行过程进行理论分析和设计计算,得出主要结构参数,并进行受力和力矩计算。分析结果表明,在膨胀过程中,一级转子的总力矩始终为正值,膨胀将结束时两转子的总力矩变为负值。在角度θ2之前,二级转子的驱动力矩大于一级转子的驱动力矩,在角度θ2之后,一级转子的驱动力矩更大。     

烟气轮机新型轴毂联接计算及工艺实现

介绍了进口烟气轮机轮盘与主轴间新型轴毂联接技术的结构与特点,分别计算了中心杆螺栓在高温工作时所需的剩余预紧力和伸长量以及常温下应有的预紧伸长量;论述了中心杆螺栓内置热源加热预紧的工艺控制过程。     

氧氮液化装置优化操作

简介马钢YPON-3750/1710型氧氮液化装置流程,叙述氧氮液化装置在热开车、冷开车、冷备状态开车、变工况操作中存在的问题,阐述了为解决问题而采取的优化操作方法及取得的效果。     

铜陵有色35000m~3/h空分设备膨胀机转速异常的故障排除

铜陵有色35000 m3/h空分设备配套的2台膨胀机中的1台,因为转速仪表的信号受到干扰而发生转速信号异常现象,导致膨胀机增压端回流阀全开,影响空分设备的安全运行。简介膨胀机的技术参数和转速仪表的特点,阐述采取的排除措施及其效果。