Mathematical model and energy efficiency analysis of Siemens reactor with a quartz ceramic lining

Abstract

• A quartz ceramic lining for enhancing energy efficiency is proposed. • A CFD model considering the operating and design parameters is developed. • A potential maximum deposition radius for rods can be achieved. • The interactive effects of parameters on energy efficiency are performed. • Average energy consumption for Siemens reactor can be reduced substantially. A parametric study was conducted for the cost reduction of polysilicon by decreasing the electrical energy loss of an existing Siemens reactor. In this work, a quartz ceramic lining was applied onto a reactor vessel, and the hot emitter mechanism was adopted to enhance the energy efficiency for the production of polycrystalline silicon. The effects of the geometrical and heat transfer parameters on the energy efficiency and productivity of the Siemens reactor were examined. Our results indicate that the ceramic lining behaved similarly to thermal insulators by restricting the heat transfer through the ceramic lining, causing the lining surface facing the heated polysilicon rod to emit thermal radiation, thus contributing to reactor’s energy efficiency. The results further demonstrated that the impact of the ceramic lining emissivity on the total radiated heat loss was very small. Furthermore, by addition of a quartz ceramic lining, there is a noteworthy reduction in the total electrical current, resulting in a smoother radial-dependent temperature and thermal stress distribution; thus, a higher deposition radius for the rods can be achieved. According to the energy efficiency analysis, the average energy consumption for the existing 24-rod Siemens reactor can be decreased from 55 kWh per kilograms polysilicon to approximately 36 kWh per kilograms polysilicon.