大型气液同轴喷射分布器数学模拟

Mathematical Simulation of Large Gas-Liquid Co-Injection Sparger

大型浆态床的气液分布器设计需要同时考虑气体均布、气液传质和防止堵塞三个方面的要求,基于此提出了一种大孔径气液同轴喷射的分布器构型.首先通过单喷嘴冷模实验测量了全塔平均气含率和大、小气泡相含率,证明气液同轴喷射能够显著强化气液传质,减小气泡直径.随后对所设计的外径6.3 m的多环大型气液分布器内部的流动进行了三维瞬态模拟以探讨改进气体均布的措施,模拟发现,对于多环分布管结构,采用管径随环径增大的变直径分布器代替常用的等直径分布器能够明显改善气体分布的均匀性.最后对该分布器在不同载荷下的气体均布指标进行了计算机模拟,结果表明在±40%的负荷变化范围内,分布器的气体均布性能仍然比较稳定,能够满足工业应用的要求.

The requirements of gas uniform distribution, gas-liquid mass transfer and blockage prevention are all needed to consider when designing a gas-liquid sparger for large slurry reactor. Based on this, a kind of gas-liquid co-injection sparger with large nozzle diameter was proposed. Firstly, the average gas holdup and phase holdup of large and small bubble were measured through cold-test experiment while the sparger was single nozzle, which proved that gas-liquid co-injection could significantly enhance gas-liquid mass transfer and reduce bubble diameter. Subsequently, we carried out 3 D transient simulation of the flow inside the designed large multi-ring gas-liquid sparger whose outer diameter was 6.3 meter to explore the methods to improve the gas uniform distribution. The results showed that the maldistribution could be significantly addressed by replacing usual constant diameter distributor tube with variable diameter distributor tube whose diameter increases with ring diameter. Finally, the performance of the gas-liquid sparger under different loads was simulated, the results showed that the gas distribution performance of the sparger was stable with ?40% load fluctuation and the sparger could meet the requirements of industrial application.