The Computational Transport Of The Polysilicon CVD Reactor

The purpose of the paper is to develop a novel energy saving polysilicon CVDreactor. In order to guide the optimization and design of the reactor and reduce theenergy consumption, the flow behavior, the heat and mass transfer, the speciestransport and chemical vapor deposition reaction in the polysilicon CVD reactor havebeen modeled by using the computational fluid dynamic method.In the second part of this dissertation, the structure of the polysilicon CVDreactor and the operation process have been introduced, the arrangement of thepolysilicon rods has been analyzed; the inlet and outlet of the gases have beendiscussed and several cooling structures of the chassis have been presented.In the third part, the radiation heat transfer of the reactor has been simulated byusing the S2S model. The simulation results demonstrate that enlarging the reactorcapacity from12rods to18rods and27rods can reduce the energy loss by7.8%and20.8%respectively; if the polysilicon growth rate is increased from5to20μm min-1,the radiation energy consumption can be reduced by75%; increasing the inner shieldtemperature from373to773K, the energy saving is9.6%; changing the emissivity ofthe inner shield from0.2to0.1decreases the energy loss by38.3%. Furthermore, theradiation energy consumption has been compared between the circular arrangementreactor and the hexagonal arrangement reactor. The results show that the radiationpower in the circular arrangement reactor between the polysilicon rods and the reactorwall is lower than that in hexagonal arrangement reactor and the power in the circulararrangement reactor between the polysilicon rods are more than that in hexagonalarrangement reactor, the results demonstrate that the polysilicon rods arrangement inthe circular arrangement reactor is more encryption than that in hexagonalarrangement reactor.Based on the traditional polysilicon CVD reactor, a novel reactor with lowerenergy consumption is developed and a three dimensional theoretical model todescribe the transport phenomena in the reactor is proposed. An overall chemicalreaction formula is developed according to the measured composition of the exhaustgas in a polysilicon factory. By comparing the simulated results with industrial datafor traditional polysilicon CVD reactor, the proposed model has been verified. Thevelocity profile, temperature field, concentration distribution and the energyconsumption of the traditional reactor and novel reactor have been analyzed using the theoretical model. The simulation results demonstrate that the flow pattern of the gasmixture in the novel reactor is nearly plug flow, which is fundamentally different fromthat of traditional reactor, and the temperature field can be controlled by changing theoperating parameters in the novel reactor. Because the temperature of the gas phase inthe novel reactor can be controlled, the chance of silicon powder generation can beavoided, and the cleanness of the inner wall of the reactor can be kept at95%above.Simulation results shows that the energy consumption of the novel reactor can begreatly reduced due to lower radiation on the cleaner inner wall.Finally, the paper presents a novel cooling structure of the chassis in polysiliconCVD reactor, the flow behavior in the novel chassis has been modeled by using thecomputational fluid dynamic. The simulation result demonstrate that by reducing thesize of the electrode sleeve and the distance between the electrode sleeve and thebottom plane of the chassis can increase the uniform of the mass flow between theelectrode sleeves; changing the distance between the middle plane and the bottomplane in the chassis can also increase the uniform of the mass flow between theelectrode sleeves.