Radiation heat savings in polysilicon production: Validation of results through a CVD laboratory prototype

Author-Highlights
• Energy savings in polysilicon production CVD reactors are explored.
• Energy savings are focused on the radiation heat loss phenomenon.
• A theoretical model for radiation heat loss is experimentally validated.
• Relevant parameters that affect radiation heat loss and their impact are put forward.
• With an adequate reactor design, the radiation heat loss can be reduced by 25%.

This work aims at a deeper understanding of the energy loss phenomenon in polysilicon production reactors by the so-called Siemens process. Contributions to the energy consumption of the polysilicon deposition step are studied in this paper, focusing on the radiation heat loss phenomenon. A theoretical model for radiation heat loss calculations is experimentally validated with the help of a laboratory CVD prototype. Following the results of the model, relevant parameters that directly affect the amount of radiation heat losses are put forward. Numerical results of the model applied to a state-of-the-art industrial reactor show the influence of these parameters on energy consumption due to radiation per kilogram of silicon produced; the radiation heat loss can be reduced by 3.8% when the reactor inner wall radius is reduced from 0.78 to 0.70 m, by 25% when the wall emissivity is reduced from 0.5 to 0.3, and by 12% when the final rod diameter is increased from 12 to 15 cm.