Abstract: Calcium carbide (CaC2) synthesis is a typical high-temperature solid-phase reaction. By reducing the particle sizes of raw material, the intra- and interparticle heat and mass transfer can be significantly improved, thus realizing calcium carbide synthesis at relatively low temperatures and then driving technological revolution. Based on this, a fluidized bed CaC2 synthesis process was proposed in this study, and the reaction characteristics and hydrodynamics of CaC2 synthesis from small-particle raw materials were investigated in a fixed bed and spouted fluidized bed, respectively. Besides, the reactions on the particle surface and its morphological changes during the reaction were analyzed, and the defluidization mechanism was further explored. The results showed that for raw materials with particle sizes of 147~178 μm, CaC2 synthesis reaction can occur at 1500℃, and the reaction rate significantly increased when the temperature was above 1600℃. At 1600℃, the C2H2 yield and CaO conversion rate can reach up to 101~105 mL/g and 25%~26%, respectively. As the C:Ca molar ratio of raw materials was less than 9.6, the defluidization occured when the fluidized bed was operated at 1500~1600℃, and a large number of coke particles were found to adhere to the surface of CaO particle. The bed defluidization was caused by the particle agglomerates, which were formed through the sintering of CaO particles and bonding between CaO and coke particles. It was found that the former was the dominant factor causing defluidization, and increasing the concentration of coke particles in the bed can avoid this. Therefore, this study verified the feasibility of fluidized bed solid-phase CaC2 synthesis and provided a novel approach and data support for technological revolution in the field of CaC2 production.

Key words: fluidized bed, calcium carbide, small-size particle, gas-solid flow characteristics, defluidization

摘要： 电石合成是典型高温固相反应，通过减小原料粒径可显著提高颗粒内和颗粒间的传质传热速率，有望实现该过程的低温化和技术变革。基于此，本工作提出流化床合成固相电石工艺，分别在固定床和喷动流化床反应器中考察了小颗粒原料合成电石过程的反应和气固流动特性，探究了流化床中颗粒表面反应及形貌变化过程，阐述了流化床合成电石过程中床层失流机制。结果表明，对于147~178 μm的焦炭和氧化钙原料，电石合成反应在1500℃时即可发生，在1600℃时反应速率显著增加，1600℃时产物乙炔收率和CaO转化率分别可达101~105 mL/g和25%~26%；当原料C:Ca摩尔比小于9.6时，焦炭-氧化钙流化床在1500~1600℃出现失流现象，且大量焦炭颗粒黏附于氧化钙颗粒表面；流化床失流是由床内颗粒团聚造成的，团聚物形成途径包括氧化钙颗粒间烧结团聚和焦炭-氧化钙颗粒间黏结，但前者是引发失流的主导因素，提高床内半焦颗粒浓度可避免失流发生。本工作验证了流化床合成固相电石工艺的可行性，可为电石生产技术变革提供技术思路和数据支撑。

关键词: 流化床, 电石, 小颗粒, 气固流动特性, 失流