Numerical Modeling of Thermal Plasmas Used for Radioactive Waste Treatment

• Main Author: 陳亮瑜
• Other Authors: Ta Chin Wei
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/71717570051050971471

碩士 === 中原大學 === 化學工程學系 === 88 === Thermal plasma technology takes the advantages to incinerate the combustible parts of the radioactive wastes for volume reduction and to vitrify the noncombustible counterparts simultaneously into glassy slags with limited pretreatment steps. In this study, a mathematical model of thermal plasma torches was developed. Mass, energy, and momentum conservation equations coupled with detailed reaction mechanism were solved to study the effect of operating conditions on the temperature, flow field, and species concentration in the plasma reactor. It was found that an increase in the current intensity results in increases of gas temperature and velocity. Increasing the feed flow rate only results in an increase of gas velocity. The gas temperature and velocity is lower in air plasma than in argon plasma under the same operating condition. A large amount of NOx was produced in N2/O2 plasmas. Reducing the oxygen content in the feed of N2/O2 plasma can’t effectively reduce the emission of NO. The transferred arc plasma torch is more energy-efficient than other arc plasma torches. Finally, The melting process of radwaste surrogates in plasma melting furnace is simulated. It was found that an 800 cm3 radwaste surrogate could be totally molten within 47 minutes in a furance equipped with an 100 kW non-transferred plasma torch.