关键词: 流化床, 电石, 小颗粒, 气固流动特性, 失流

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