共查询到20条相似文献,搜索用时 140 毫秒
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气升式内环流反应器流场及传质特性数值模拟 总被引:3,自引:0,他引:3
采用双流体模型和气液二相流体动力学理论建立了气升式环流反应器流体流动的数学模型,在此模型的基础上利用溶质渗透理论和各向同性湍流理论建立了局部液相体积传质系数数学模型。采用计算流体软件F luent对气升式环流反应器内气液二相流动状况进行模拟,模拟结果较好地解释了气升式环流反应器内的流动行为及传质特性。模拟计算值与文献实验值的吻合说明了模型的可行性。 相似文献
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就气升式环流反应器的类别、操作条件和几何结构对环流反应器内两相流体力学行为的影响规律进行了评述。根据环流反应器的流体力学特性和传质特性指出了环流反应器的应用领域及要求。列举了环流反应器在工业上的应用实例。 相似文献
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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。 相似文献
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Ivana M. Šijački Radmilo R. Čolović Dragan Lj. Petrović Miodrag N. Tekić Mirjana S. Ðurić 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2010,85(1):39-49
BACKGROUND: Bubble columns (BCs) and airlift reactors (ALRs) have important applications as bioreactors, chemical reactors and as contactors in waste‐water treatment. The liquid phase properties in these reactors significantly influence the main hydrodynamic and mass transfer characteristics. Dilute alcohol solutions can be used to simulate real industrial systems in bioreactors. However, only a few research studies have considered such systems. The aim of this paper is to broaden the existing experimental data related to the influence of alcohol addition on the main characteristics of draft tube airlift reactors (DT‐ALRs), and to propose simple correlations for their prediction. RESULTS: New experiments were conducted in a DT‐ALR with a single orifice sparger, and with dilute aliphatic alcohol solutions from methanol to n‐octanol. Also, simple correlations were developed to predict the gas hold‐up and volumetric mass transfer coefficients in BCs and DT‐ALRs, but also the downcomer liquid velocity and liquid circulation time DT‐ALRs with single orifice sparger and dilute alcohol solutions. The proposed correlations included, in addition to the superficial gas velocity, the surface tension gradient as the only factor to characterize the liquid phase. CONCLUSIONS: General conclusion can be made that the gas holdup increased, but the downcomer liquid velocity decreased in a DT‐ALR, with increase in surface tension gradient of the alcohol solutions. Also, very good agreement was achieved between experimental and calculated data, by applying the developed correlations, with relative average errors less than 5%, except for gas hold‐up, where it was in the range 8–32%. Copyright © 2009 Society of Chemical Industry 相似文献
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Jaroslav Klein tefan God Jos A Teixeira 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2006,81(11):1778-1786
A low‐cost and simple magnetic particle tracer method was adapted to characterize the hydrodynamic behavior of an internal‐ and an external‐loop airlift reactor (ALR). The residence time distribution of three magnetic particles differing in diameter (5.5, 11.0 and 21.2 mm) and with a density very close to that of water was measured in individual reactor sections. The measured data were analyzed and used to determine the velocity of the liquid phase. Validation of the experimental results for liquid velocity was done by means of the data obtained by an independent reference method. Furthermore, analysis of the differences found in the settling velocity of the particle in single‐liquid and gas‐liquid phases was carried out, using a simplified 3D momentum transfer model. The model considering particle‐bubble interaction forces resulting from changes in the liquid velocity field due to bubble motion was able to predict satisfactorily the increase in the particle settling velocity in the homogeneous bubbly regime. The effective drag coefficient in two‐phase flow was found to be directly dependent on particle Reynolds number to the power of ? 2 but independent of gas flow‐rate for all particle diameters studied. Based on the experimental and theoretical investigations, the valid exact formulation of the effective buoyancy force necessary for the calculation of the correct particle settling velocity in two‐phase flow was done. In addition, recommendations concerning the use of flow‐following particles in internal‐loop ALRs for liquid velocity measurements are presented. Copyright © 2006 Society of Chemical Industry 相似文献
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Jaber Gharib Mostafa Keshavarz MoravejiReza Davarnejad Mohamad Ebrahim Malool 《Chemical Engineering Research and Design》2013
Gas holdup and gas–liquid mass transfer coefficient were considered in an external airlift reactor. Air was sparged through some aliphatic alcohols (methanol, ethanol, n-propanol, and n-butanol) with different concentrations (0–1%, v/v). It was observed that gas holdup and mass transfer coefficient increased with increasing the number of carbons in alcohols. Furthermore, an increment in alcohols concentration increased gas holdup and mass transfer coefficient. The same behavior was observed in external and internal loop airlift reactors although gas holdup and mass transfer coefficient values were less than those of internal airlift reactor. According to the experiments, two correlations for gas holdup and mass transfer were developed. 相似文献
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在一具有四室的气-液-固三相多室气升式环流反应器(MALR)中,利用电导脉冲示踪技术研究了空气-水及不同浓度的乙醇水溶液-聚苯乙烯三相物系在MALR中的混合特性(混合时间和波登斯坦准数与两个上升室的表观气速和不同体积浓度的乙醇水溶液间的关系)。实验结果表明,两上升室的表观气速和乙醇溶液的浓度对器内的轴向分散和混合均有影响,但MALR的返混程度是比较小的。 相似文献
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A systematic procedure was developed for selecting the type of reactors or a reactor system configuration for polymerization reactions. Two different mechanisms were investigated, and the “best” reactor system to give the desired quality of the product was determined using a systems synthesis technique. The behavior of the system in the neighborhood of the optimal solution was explored, and the effect of variation in the rate constants and the initial concentrations of the catalyst and the monomer on the optimal reactor system was examined. Recycle streams were introduced and their effect on the system performance was investigated, and finally the applicability of the systems synthesis technique to other polymer reactor design problems was discussed. 相似文献
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气升式环流反应器强制振荡周期对传质影响的研究 总被引:2,自引:0,他引:2
在同一反应器中比较了不同振荡周期下的气液传质特性,为最优强制振荡周期的确定提供了实验依据和分析基础。选择体积传质系数及气含率作为传质研究的主要评价指标,实验结果表明,动态操作下的传质效果明显优于稳态,而不同振荡周期传质效果也大不一样。在0.8~2.4m3h-1的气速范围内,由静压力、导流管顶部截面流体速度、全床气含率(及传质系数)周期性变化所确定的振荡周期TP、TV、TK比稳态操作下的全床平均传质系数分别提高了3.92%~27.3%,2.35%~24.5%,28.2%~43.3%。由反应器内全床平均气含率或传质系数确定的振荡周期TK是最佳振荡周期。 相似文献
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Csaba Horvath Lawrence H. Shendalman Richard T. Light 《Chemical engineering science》1973,28(2):375-388
A novel reactor, made by coating the inner wall of tubes with an enzyme resin layer, was mathematically modeled. Michaelis-Menten kinetics, laminar flow and isothermal conditions were assumed and substrate diffusion in both the streaming fluid and the catalyst annulus was taken into account. The behavior and effectiveness of the reactor are discussed in terms of characteristic dimensionless groups including the reactor coordinate which is inversely proportional to the average overall rate at a given conversion. An experimental criterion is given for the absence of all diffusional effects which may mask kinetic data. The calculated reactor coordinates can be approximated by the sun of their limiting values pertaining to the kinetically controlled and bulk diffusion controlled reaction thus permitting a simplified treatment of the reactor data and of problems of reactor design. Conditions for extracting kinetic parameters from experimental data are discussed. 相似文献
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The steady state and dynamic behavior of a continuous stirred tank reactor has been analyzed for free radical solution polymerization of styrene initiated by a mixture of two initiators having different thermal stabilities. From the steady state analysis of the reactor model with a mean residence time as a bifurcation parameter, four unique regions of steady state solutions are identified in an operating parameter space for a given initiator feed composition. A variety of complex bifurcation behavior such as multiple steady states, Hopf bifurcation and limit cycles have been observed and their stability characteristics have been analyzed. The effects of feed initiator composition and the concentration of the initiator in the feed stream on the reactor dynamics are also presented. 相似文献