Application of Oil-Gas Hybrid Bearing Turbine-Expander in EAST Helium Cryogenic System

Fusion energy with much more advantages could become a serious option for the future energy. The EAST (Experimental Advanced Superconducting Tokomak) device is aiming to study the physical and technical issues involved in stead-state tokamak nuclear fusion. Cryogenic system is one of the most important sub-systems in EAST device, and turbine-expanders are the key components of cryogenic system. In this paper, turbine-expanders with specific configuration in EAST cryogenic system were introduced, and the problem of instability of turbine-expanders in actual refrigerating process was pointed out. Three different refrigerating methods (Using T3, No-using T3 and using a two-phase turbine) were analyzed, and the results showed that the instability of turbine-expander, especially the coldest turbine (T3), will influence the normal operation, even the whole physical experiment of EAST device. The liquefaction capacity will be increased largely by using a two-phase turbine-expander instead of the JT-throttling.