10000m~3/h空分设备大修改造

详细介绍了对10000m3/h空分设备进行的切除贫氪氙和粗氖氦系统、整改冷箱内管道及串联蒸汽加热器和电加热器改造情况,分析了改造效果及改造后还存在的不足。     

分子筛蒸汽加热器三起事故的教训

简述了分子筛吸附系统蒸汽加热器的工作过程。分析分子筛蒸汽加热器发生的三起事故原因。总结操作方法及教训,保证设备安全运行。     

推荐一种新型的分子筛再生用蒸汽加热器

介绍大庆乙烯工程引进的一号“万立”空分,所配分子筛加热器,蒸汽外漏,多次更换无效,后采用杭氧厂的蒸汽加热器,运行四年,安全可靠,取代了林德的加热器。图3表1。     

不停车处理蒸汽加热器泄漏故障

介绍了60000m3/h空分设备分子筛纯化系统蒸汽加热器发生泄漏的经过,制定了详细的处理方案,在空分设备不停车的情况下修复了分子筛纯化系统蒸汽加热器泄漏故障。     

蒸汽加热器常见泄漏原因及在线处理

中原大化52000 m3/h空分设备由于分子筛纯化系统蒸汽加热器泄漏造成分子筛吸附器出口空气中二氧化碳含量超标,为避免非计划停车带来的损失,结合带压开孔新技术对蒸汽加热器进行在线更换。分析大型空分设备蒸汽加热器常见泄漏原因,介绍蒸汽加热器在线更换的具体方案和效果。     

分子筛再生气加热方式的改进

针对20000m3/h空分设备用于加热分子筛再生气的蒸汽加热器运行不稳定,新增1台电加热器,分子筛再生气的加热方式改为蒸汽和电加热并用,保证了空分设备的稳定运行。     

分子筛纯化系统蒸汽加热器改造

48000 m3/h空分设备用于加热分子筛再生气的节能型蒸汽加热器因为水分冻结膨胀而泄漏。对其增设排液管后,大大提高了防冻和排液性能,使它能更好地在北方极寒天气下运行。简介蒸汽加热器的主要技术参数和结构,介绍技改方案的具体实施。     

分子筛纯化系统蒸汽加热器泄漏故障的分析及预防

空分设备临时停车时,因气动蝶阀开关位失准,精馏塔内冷量外泄进入蒸汽加热器,致使蒸汽加热器管束爆裂后含有蒸汽的加热气体进入分子筛吸附器,导致分子筛失去吸附能力,影响空分设备的正常运行。详细介绍了故障的经过、原因分析及解决与预防该故障的具体操作方法和步骤。     

分子筛纯化系统蒸汽加热器泄漏的在线处理

简介齐鲁比欧西KDON-45000/30000型空分设备分子筛纯化系统蒸汽加热器的流程以及发生泄漏的经过和原因,介绍为保证空分设备安全运行而采取的临时措施,阐述蒸汽加热器的换热管组件整体在线更换的条件和实施过程,最后介绍在线更换时的注意事项。     

22000m~3/h空分设备分子筛纯化系统蒸汽加热器泄漏分析和处理

22000 m3/h空分设备分子筛纯化系统蒸汽加热器泄漏造成分子筛受潮、吸附能力下降,出口空气中二氧化碳含量增大,主冷液氧中碳氢化合物含量波动,对空分设备长周期稳定运行构成威胁。通过调整分子筛吸附器运行周期,更新蒸汽加热器内件以及改造空气预冷系统,使分子筛吸附器出口空气中二氧化碳含量达标,主冷液氧中碳氢化合物含量稳定,从而保证了空分设备长周期安全生产。     

可控硅调功技术在分子筛再生气电加热器中的应用

从可控硅调功技术的实际应用出发,介绍了可控硅调功技术的调节原理,分析了其在空分设备分子筛再生气电加热器中自动调节功率的逻辑控制和特点,并指出可控硅在工作时对环境的要求和安装使用中的注意事项,最后阐述了采用可控硅调功电加热器的效益。     

一起分子筛再生故障的应急处理与分析

介绍了一起因电加热器未启动而导致分子筛再生失败的故障和处理措施，分析了故障原因，阐述了为避免类似故障再次出现而在仪控方面所采取的改进措施。     

一起分子筛再生故障的应急处理与分析

介绍了一起因电加热器未启动而导致分子筛再生失败的故障和处理措施,分析了故障原因,阐述了为避免类似故障再次出现而在仪控方面所采取的改进措施。     

分子筛纯化系统电加热器故障分析和排除

由于电加热器插拔式控制电源小母线端子接触不良,造成电加热器在运行过程中因控制电源失电而不能正常工作。介绍故障现象和原因分析过程,阐述了处理措施和从中获得的教训。     

Bubble spreading during the boiling crisis: modelling and experimenting in microgravity

Boiling is a very efficient way to transfer heat from a heater to the liquid carrier. We discuss the boiling crisis, a transition between two regimes of boiling: nucleate and film boiling. The boiling crisis results in a sharp decrease in the heat transfer rate, which can cause a major accident in industrial heat exchangers. In this communication, we present a physical model of the boiling crisis based on the vapor recoil effect. Under the action of the vapor recoil the gas bubbles begin to spread over the heater thus forming a germ for the vapor film. The vapor recoil force not only causes its spreading, it also creates a strong adhesion to the heater that prevents the bubble departure, thus favoring the further spreading. Near the liquid-gas critical point, the bubble growth is very slow and allows the kinetics of the bubble spreading to be observed. Since the surface tension is very small in this regime, only microgravity conditions can preserve a convex bubble shape. In the experiments both in the Mir space station and in the magnetic levitation facility, we directly observed an increase of the apparent contact angle and spreading of the dry spot under the bubble. Numerical simulations of the thermally controlled bubble growth show this vapor recoil effect too thus confirming our model of the boiling crisis.     

A low‐cost dehydrogenation system of amorphous silicon thin films used for fabricating low‐temperature polycrystalline silicon

Low‐temperature polycrystalline silicon thin‐film transistors were widely employed in active‐matrix flat‐panel displays and giant microelectronics. In general, a‐Si thin films prepared by plasma‐enhanced chemical vapor deposition contain hydrogen. To prevent the ablation caused by sudden hydrogen eruption during excimer laser crystallization (ELC), two dehydrogenation systems are developed in this study to reduce hydrogen content before excimer laser crystallization. One is a ceramic heater‐based dehydrogenation system and the other is a quartz tube radiant heater‐based dehydrogenation system. The hydrogenated amorphous silicon (a‐Si : H) thin films prepared by plasma‐enhanced chemical vapor deposition are dehydrogenated by both systems. Fourier‐transform infrared absorption spectra revealed that the hydrogen content reduces after dehydrogenation processing. Raman measurements confirmed that the a‐Si : H thin films are still amorphous phase. The major potential advantages of quartz tube radiant heater‐based dehydrogenation system include rapid heating speed, good dehydrogenation quality, small footprint and low cost. Two‐steps temperature rise method is a good candidate for dehydrogenation processing because it provides sample with low thermal distortion.