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为了生产价廉的太阳能级高纯度硅,基于用二氧化硅碳热还原成金属硅的热力学研究,开发出了一台交流电弧炉。炉子的特点是有封闭型炉身和带有电弧电极和加料喷管的炉缸。作为还原剂用的碳球团从炉顶加入炉内,二氧化硅粉被加到炉缸内温度最高区域内。在炉身下部,反应 SiO_2+C→SiO+CO 和 SiO十2C→SiC+CO 所产生的 SiO 和 SiC,由反应 SiO+SiC→2Si+CO 而得到 Si。熔融的 Si 积蓄在炉缸中并从出铁口排出。炉子的生产率约为2kg/h,硅收得率一般为83%。分析表明,硅中杂质 B<0.1ppmw(百万分之一,重量,以下同),Fe<12ppmw,其他元素<5ppmw,用此种硅脱碳提纯和单方向凝固之后制造的单晶太阳电池的光电转化率是16.5%,此值与用半导体级硅制成太阳电池的光电转化率相等。
In order to produce low-cost, solar-grade, high-purity silicon, an AC electric arc furnace was developed based on a thermodynamic study of carbon-carbon reduction to silicon metal. The furnace features a closed shaft and a hearth with an arc electrode and a feed nozzle. The carbon pellets used as reductant are added to the furnace from the top of the furnace, and the silica powder is added to the highest temperature in the furnace. In the lower part of the shaft, the reaction of SiO 2 + C → SiO + CO and SiO 十 2C → SiC + CO generated SiO and SiC, the reaction of SiO + SiC → 2Si + CO to obtain Si. The molten Si is accumulated in the hearth and discharged from the tap hole. The productivity of the stove is about 2kg / h, the yield of silicon is generally 83%. The analysis showed that impurities B <0.1 ppmw (parts per million by weight, the same below), Fe <12 ppmw, and other elements <5 ppmw in silicon were used for the single crystal solar cell manufactured after decarburization purification and unidirectional solidification The photoelectric conversion rate is 16.5%, which is equal to the photoelectric conversion rate of a solar cell made of semiconductor grade silicon.