分段进气多级环流反应器流动与传质特性研究

摘要

多级环流反应器通常在段间安装多孔分布板或其他内构件,增加了流体流动的阻力,导致环流液速降低.为此,文中在多级环流反应器研究的基础上,设计了一种新型分段进气、多级环流反应器,利用新通入气体的抽提力和喷射力,缓解了段间的流动压降,并加速气泡的破碎;重点考察了进气量在各段中的分配比例对分段进气多级环流反应器流体力学的影响.应用电导率仪和溶解氧分析仪分别测量环流液速、混合时间及体积传质系数.实验结果表明:分段进气时,第2段和第3段中的环流液速比较高,并明显高于多级环流反应器中的环流液速;不同的操作条件下,上下二端的混合时间差距明显,表现出串联反应器特性;体积传质系数远高于多级环流反应器,最大值约为多级环流反应器的2.4倍.%The perforated plates or other internals in multi-stage airlift loop reactor (MSALR) increase the fluid flow resistance,resulting in the decrease of circulating liquid velocity.A novel multi-sparger and multi-stage airlift loop reactor (MS-MSALR) was designed,by which the flow pressure drop was reduced and the bubble breaking was enhanced with the ejection force of fresh gas.It focuses on the effect of gas inlet ratio on the hydrodynamics of MSMSALR.The gas-liquid two-phase flow hydrodynamic properties including liquid circulation velocity,mixing time and volumetric mass transfer coefficient at various ratios were measured by conductance electrode and DO probe.The experimental results show that the liquid circulation velocities of the MS-SMALR are much higher than that of multi-stage loop reactor,and the mixing times measured in the top and bottom downcomers are very different,which makes MS-MSALR look like a multi-stage series reactor,while the volumetric mass transfer coefficients of TS-MSALR are much higher than that of multi-stage airlift loop reactor.The maximal mass-transfer coefficient of the MS-MSALR is 2.4 times of the multi-stage reactor.