三相多室气升式环流反应器气含率的研究

在1个4流道的三相多室气升式环流反应器中,以空气-水-K树脂为体系,采用压差法测量气含率,考察了上升室气体表观速率、固体装载量对上升室与下降室气含率的影响.结果表明:上升室的气含率随着该室气体表观速率增加而增加,而随着另一上升室气体表观速率增加而略有降低;下降室的气含率随着该室气体表观速率增加呈现3种变化趋势,而随着另...     

多管环流反应器的气含率研究

提出了一种新型结构的多管式环流反应器,对于空气－水体系,在每个上升管气速为０～０．１６ｍ／ｓ和管径比Ｄｄ／Ｄｒ＝０．３～１．０范围内,研究了两个上升管气速及不同管径比时上升管气含率的变化规律,同时研究了分离箱中静液高及分离箱结构参数与下降管气含率之间的关系。提出了在鼓泡流区域内上升管气含率模型方程：Ｅ１＝αＵｂｇ１－ｃＵｇ３     

三相多室气升式环流反应器中上升室气含率研究

在一个4流道的多室气升式环流反应器中,以空气-水-K树脂为体系,考察了上升室气体表观速率和固体装载量对上升室气含率的影响。结果表明:上升室的气含率随着该室气体表观速率增加而增加,而随着另一上升室气体表观速率增加而略有降低;上升室的气含率均随固体装载量增加而降低。在鼓泡流下,根据漂流通量模型,建立了上升室的气含率模型;上升室气含率的模型计算值和试验值的平均相对误差为6.429%。     

多室气升式环流反应器的气含率研究

在四流道的多室气升式环流反应器中 ,常温常压下 ,以空气作为气相 ,以水、0 .5 %、1%、5 %NaCl及 0 .5 %、1%、5 %Na2 SO4 作为电解质 ,考察上升区气含率与操作气速及电解质密度的变化规律。并用回归分析的方法 ,建立了上升区气含率与电解质密度的半经验关联式 ,用该式得到的上升区气含率的计算值和实验值的平均相对偏差为 2 .5 8%。     

多室气升式环流反应器流动特性的数值模拟

在空气-水两相多室气升式环流反应器（MALR）中,采用欧拉欧拉两相流模型对扇形反应室内气液两相流动过程进行了数值模拟研究,考察了上升室的气含率、液体速度随表观气速的变化,最后用实验数据对模拟结果进行了验证.结果表明,某一上升室气含率受该室表观气速的影响较大,与另一上升室表观气速的影响较小;循环液体与上升室流体流动型式有关;气含率和循环液速的模拟值与实验值的平均相对误差分别为5.36％和8.28％;说明了应用数值模拟方法研究MALR流动特性的可行性.     

气升式环流反应器数值模拟研究进展

介绍了计算流体力学在气升式环流反应器(二相、三相)中的应用,汇总并介绍了气升式环流反应器的气含率和循环液速的二维与三维数值模拟结果,提出今后进一步的研究方向。     

气升式振荡环流反应器的数值模拟和结构优化

气升式振荡环流反应器（ARLR）作为一种新型的气升式环流反应器,能够有效地提高反应器的气含率和传质系数,并已得到生物发酵实验的验证。本文通过CFD的手段研究了反应器内的流动和传质状况,并利用CFD模拟和响应面分析相结合的方法,优化了反应器的结构参数,如高径比（H/D）、升液区降液区面积之比、导流筒高度等。经过实验测量,优化后的气升式振荡环流反应器与传统的气升式环流反应器相比,气含率提高了32%以上,传质系数提高了11%以上。结果表明,气升式振荡环流反应器作为生化反应器有着非常广阔的应用空间。     

旋流气升式环流反应器的局部气、固含率研究

新开发的有机玻璃制成的旋流气升式环流反应器高为2m、内径75mm,内部的导流筒(材料为PVC)高1.5m、内径30mm、壁厚1mm且装有10组扇形翅片。以空气-水为两相物系、空气-水-K树脂为三相物系,常温常压下,利用直接取样法和压差法测量了上升区局部的气含率、固含率,研究了不同底部间隙、不同固体装填体积分数下表观气速和轴向高度对上升区气含率、固含率的影响规律。结果表明:在均匀鼓泡流时上升区气含率随着表观气速的增大而增大,随着固体装载量的增加而下降;在非均匀鼓泡流时,三相物系的气含率高于两相物系的气含率。随着上升区轴向高度的增大,上升区局部气含率变化不大;底部间隙越大,气含率越小。在轴向高度较低时上升区固含率随着轴向高度的增大而减小,轴向高度较高时上升区固含率基本保持不变。     

气升式环流反应器流动特性的数值模拟

应用Fluent计算流体力学软件,通过数值模拟的方法考察了气升式环流反应器内导流简直径、导流筒高度、导流筒安装高度以及液相进口速度对反应器内两相流动的影响。计算结果表明：导流简直径增大。液相循环量和上升段气含率均增大;导流筒高度增大,液相循环速度和循环量均增大,但是当导流筒的高径比增加到6．3后,液相循环速度和循环量反而减小;导流筒安装高度增加．液相循环速度及循环量均增大,升液管气含率降低;增加液相的进口速度,虽然上升段的液速有所增加,但是降液管循环液速及循环量基本不受影响。最后计算了反应器内液相速度随进口气速的变化情况,并与实际测量值进行了比较,模拟值和测氨值都表明随着进口气速的增加,液相循环速度随着进口气速的增加而增加．两者呈现良好的一致性。     

气升式内环流反应器的气含率研究

建立了气升式内环流反应器的冷模实验装置,以空气-水两相系统为研究对象,采用压差法测定了反应器降流区的气含率和升流区气含率,采用体积膨胀法测定了反应器总体平均气含率.通过改变导流筒直径、高度及底部封头形状,考察了结构参数对气含率的影响;通过改变通气量和上清液高度考察了操作参数对气含率的影响.建立了气含率的数学模型,并将试验数据拟合,得到不同结构反应器的模型参数.     

底部间隙对多室环流反应器流动特性的影响

在空气-水-石英砂三相多室气升式环流反应器(MALR)中,调节底部转角连接处间隙高度分别为18,28,38mm,在表观气速1.2～4.2cm/s范围内,实验研究了底部阻力系数、相含率、循环液速随反应器底部间隙的变化规律。结果表明,随着底部间隙的增大,底部转角处的局部阻力系数减小,循环液速增大,流体夹带进入下降室的气泡和固体颗粒均增多,下降室的气含率和固含率均增大。     

Simulation and experimentation on the gas holdup characteristics of a novel oscillating airlift loop reactor

BACKGROUND: The classical airlift loop reactor (ALR) has been widely used in petrochemical, biochemical, energy and environmental processes due to such advantages as simple structure, without motional mechanism, easy sealing and low energy consumption. A novel ALR has been designed using forced periodic reversible ventilation, termed an airlift reversible loop reactor (ARLR). RESULTS: Using computational fluid dynamics (CFD) simulation and experimental validation, the mass transfer characteristics of the ARLR were studied. The simulation results predicted the experimental data well, especially at low ventilation capacity. The oscillation period had significant effects on gas holdup and the mass transfer coefficient of the ARLR. When ventilation capacity was increased from 0.22 to 3.49 vvm, compared with central airlift and annular airlift reactors, ARLR increased the mass transfer coefficient by 9–31% and 10–58%, respectively, according to simulation results, and by 11–25% and 14–58%, respectively, according to experimental data. CONCLUSION: The results showed that the ARLR could significantly enhance gas holdup and mass transfer coefficient compared with traditional central airlift and annular airlift reactors. Results indicated that the optimum oscillation period decreased with increase of ventilation capacity. ARLR has the potential for application in aerobic fermentation. © 2012 Society of Chemical Industry     

Hydrodynamics of a novel multi-stage external loop airlift reactor

In the present investigation a novel multi-stage external loop airlift reactor with hydro-dynamically induced continuous bubble generation, breakup and regeneration has been proposed. The system has been designed to operate with relatively large sized bubbles, so that interfacial circulation can be induced in the liquid-bubble interfaces and faster transfer of components can take place by turbulent diffusion through the interface of the bubbles and also due to the physical rupture and reformation of the bubbles. The system was also designed to operate in three stages operating in series so that in each stage completely deaerated liquid could be brought in contact with freshly generated bubbles. Detailed studies on the gas holdup and liquid circulation velocity have been carried out with respect to various values of superficial gas as well as liquid velocities. The gas holdup of the proposed multi-stage system is 45% higher than the single stage system, which results in better mass transfer characteristics. Empirical correlations describing the performance of the proposed reactor have been presented in this paper.     

气升式内环流反应器内局部气含率径向分布

The local gas holdup profiles in an internal-loop airlift reactor were studied experimentally by using dual electrical conductivity probe under different conditions,including superficial velocity,surface tension and liquid viscosity.The results showed that the radial gas holdup profile has a parabolic shape,which was consistent with the empirical model of Luo.Local gas holdup distribution parameters were obviously influenced by flow regime and almost remained unchanged in the same flow regime.In the gas distributor region,the profiles were steeper in the homogenous flow regime than in the heterogeneous flow regime.However,in the stable region,there was an inverse change trend in two flow regimes.The increase of surface tension,superficial velocity and liquid viscosity made the profile of local gas holdup steeper in two flow regimes.     

高长径比三相内环流反应器中相含率的分布研究

在长径比为22的三相内环流反应器中,常温常压下,以空气-水-石英砂为物系,根据无因次准数建立了气含率、固含率的预测模型,考察了在不同粒径下上升区气含率、下降区气含率和上升区固含率、下降区固含率随表观气速的变化规律和不同固体体积分数下轴向固含率的分布情况。结果表明：不同粒径下上升区和下降区气含率均随表观气速的增大而增大;当粒径（ds）≤0．3mm时,上升区固含率随表观气速的增加呈平缓趋势,下降区固含率随表观气速的增加而增加,当0．3mm〈d。≤1．2mm时,上升区固含率随表观气速的增加而呈先下降后增加的趋势,下降区固含率随表观气速的增加而下降;不同固体体积分数下的固体颗粒的固含率随着轴向高度的增大而变化平缓,能够均匀的分布在反应器中;气含率和固含率的计算值和实验值吻合较好,其平均相对误差分别为6．32％、4．56％。