Numerical analysis of preheating effect on CO methanation reactor performance

• Main Authors: Chen, Xian-Hong, 陳憲宏
• Other Authors: Sheu, Wen-Jenn
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/as59u4

碩士 === 國立清華大學 === 動力機械工程學系 === 107 === This paper investigates how surrounding setting affects the CO methanation in catalyst Ni/Al2O3 tubular fixed bed reactor by numerical analysis with commercial software COMSOL. The settings include length of the tube before reactants contact the catalyst, heat loss from wall and inlet, flow rate and materials of reactor. Since CO methanation is a strong exothermic reaction and is sensitive to the reaction temperature, we need not only consider the catalyst region but also the whole tube. As a result, adiabatically, longer the tube before reactants contact the catalyst, the higher will the temperature increases. This paper considers three different materials, stainless steel(AISI 316),aluminum (ASTM 6061-T6) and copper( copper content>95%). Each material has different thermal conductivity which plays an important role in heat transfer. Cases show that copper can achieve better temperature consistency. In addition, we consider different heat convection coefficient in order to simulate heat dissipation of the reactor outer surface. With better heat dissipation, the reactor can withstand a greater range of inlet temperature. Furthermore, we discover that the heat of reaction will increase the reaction temperature and also preheats the reactant gas by conduction from the wall of reactor. Consequently, once the reaction initiate, temperature rises which promotes the probability of air molecular collision and thus making reaction rate even faster resulting in that the reaction almost only take place at the front end of the reactor. Therefore, with appropriate preheating and heat transfer of reactor wall, we can achieve a greater performance of CO methanation.