CSRm Ultra-High Vacuum System

The new accelerator project （ HIRFL-CSR ） constructed at the Heavy Ion Research Facility in Lanzhou （HIRFL） is approaching completion. It is a multipurpose cooler-storage-ring system, consisting of a maim ring （CSRm）, an experimental ring （CSRe） and two transfer beam lines. The UHV system of CSRm is the most representative subsystem in the project. To minimize the beam loss due to charge exchange of the heavy ions with the residual gas molecules, the pressure of the CSRm vacuum system should reach 3.5 × 10^-9 Pa （N2 equivalent） and the pressure of 8 × 10^-10 Pa is expected for very heavy ion such as uranium to make its lifetime longer than 50 s in the ring. Now, the vacuum system of CSRm has been completed and a pressure less than 5 × 10^-10 Pa has been obtained. In this paper the layout of the CSRm vacuum system, the vacuum equipment in CSRm, the treatment method for the CSRm vacuum chambers, and the installation and operation of the system will be reported.

An ingenious approach of determining hydrogen isotope solubilities, diffusivities and permeabilities in GWHER-1 stainless steel

In this paper, by using an ingenious method, the hydrogen isotope solubilities and diffusivities in GWHER-1 stainless steel have been determined by a vacuum heating degassing approach at the temperature range of 597-1022 K on a set of specimens with different sizes previously charged for 24 h under a hydrogen isotope pressure of 105 Pa in the temperature range of 800-1000 K. The permeabilities are then derived from the relation Φ = DKs. It is found D = 1.52 ×10^-6exp（-54100/RT）, Ks = 2.2×10^-exp（-5400/RT） and Φ = 3.3 ×10^-12exp（-59500/RT） for hydrogen, where Ks （Sieverts＇ constant） is given in Pa^-1/2, D in m2.s^-1.Pa^-1/2, T in K and R=8.31 J.mol^-1.K^-1. By taking isotope effects into account, the corresponding Arrhenius relations for deuterium and tritium are also deduced.

Development of RH refining technology at Baosteel

With the strong demand for the development of automobile sheets, tin plates, household appliances, silicon steel, pipeline steel and other products as well as for the quality improvement of steel products, remarkable progress has been made in RH refining technology and equipment design since Baosteel began production more than 20 years ago. The vacuum degassing ratio of Baosteel has jumped from 35% in the initial stage when Baosteel began production, to the current ratio of approximately 60%, and will soon reach 75% in the near future. The independent innovations in RH refming technology in Baosteel, such as RH equipment optimization, vacuum decarburization, inclusion control, deoxidation, desulfurization, rhythm adjustment between primary steelmaking and continuous casting, the high efficiency of the RH refining process, and other aspects of RH technology, have all effectively met the requirements of developing new steel products, quality improvement and logistical control. Complete sets of RH equipment and refining technology have been successfully exported to the domestic steel plants. In the future, Baosteel will make further efforts to improve efficiency, stabilize production and quality, and realize special line production, so that the RH degasser will play a greater role in Baosteel.

Flow Structure in RH Vacuum Degasser Using Rotating Electromagnetic Field

An innovative steelmaking process is suggested using an electromagnetic driven swirling flow in the up-leg of an RH vacuum degasser.A physical and a mathematical model based on 300t RH vacuum degasser are developed to understand the effect of rotating electromagnetic field on the circulation flow rate and the two phases flow behavior of RH system.Both water model experiments and numerical simulation show the flow pattern and distribution of gas bubbles. The gas bubbles move towards the centre of up-leg under the effect of rotating electromagnetic field,and the accumulation of gas bubbles depends on the magnetic intensity.An optimization value of magnetic intensity was suggested in this paper.

Study of Argon/Molten Steel Two-Phase Flow in Refining of High Clean Steel Using Two-Fluid Model

RH vacuum degasser is a very important secondary refining device in the production of high quality steels. The flow field of molten steel in RH system plays a significant role in determining productivity of the equipment. The homogeneous model and VOF method were often used to predict the flow field in RH system, but these kinds of models simplified the interaction between gas bubbles and molten steel. In the present work, a numerical model of a whole RH system, including vacuum degasser, immersed legs and ladle,was built based on gas-liquid two-fluid model, and it could be used to analyze the interaction between argon bubbles and molten steel, to understand the effect of the bubble size to the flow field.