关键词: 气力输送, 粗颗粒, 稀相, 压降

Abstract: The oxidation of solid biurea with chlorine in aqueous solution to produce azodicarbonamide was experimentally studied in a 1 L agitated glass vessel with a four-blade paddle stirrer. Based on the film theory, a model is first developed for this system by taking the gas–liquid and solid–liquid mass transfer, solid dissolution, and instantaneous reaction between the dissolved reactants into consideration. The model can reasonably well represent the experimental data. According to the values of gas–liquid and solid–liquid mass transfer coefficients estimated with the proposed model, it is found that the gas–liquid mass transfer is a rate-controlling step in most cases, but the solid–liquid mass transfer becomes a rate-controlling step when the reaction is close to the end of this process.

Key words: azodicarbonamide, mass transfer, gas–liquid–solid reaction, rate-controlling step