共查询到19条相似文献,搜索用时 78 毫秒
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利用由静态混合器、喷嘴和分气盒组成的新型布气装置在搅拌釜式反应器中诱导生成泰勒流,对反应器流动特性及反应特性进行了实验研究。结果表明,与常规搅拌釜式反应器相比,泰勒流反应器内物料流动更加接近于平推流流型,泰勒流的生成在反应器内构建出局部平推流区域,降低了物料返混程度。反应器反应性能因流动特性改变而得以增强,相同实验条件下,在泰勒流反应器中进行的蔗糖水解反应转化率比在常规搅拌釜式反应器中高出26.7%。在一定操作范围内,局部平推流区域和反应转化率均随搅拌转速或进气量的增加而增大。泰勒流反应器可简化为平推流区和全混流区并联的流动模型,推导出了反应转化率与平推流区域占反应器总体积比率之间的关联关系。 相似文献
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采用脉冲示踪法,实验考察了泰勒反应器结构参数、操作参数和物料粘度对其停留时间分布的影响规律,发现泰勒反应器中物料的混合程度随泰勒数(Ta)的增大而增大、轴向雷诺数(Reax)的增大而减弱.进一步采用多级混合模型,将泰勒反应器的当量全混釜数(N)与反应器结构参数、泰勒数和轴向雷诺数相关联,提出了一个N的测算公式.在实验考察的范围(Ta=280~3 230; Reax=0.89~6.78)内,由该式计算的N值与实验值很好地相符,具有广泛的适用性. 相似文献
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采用定态溶氧法,实验测定了结构化反应器内的液侧体积传质系数.考察了表观气、液速度对液侧体积传质系数的影响,比较了三种不同孔密度的结构化载体(50、100和400 cpsi)内的液侧体积传质系数.结果表明,在实验的操作条件下,床层内的液侧体积传质系数随液体表观速度增大而增大:同-液速下,随气体表观速度增大亦增大.比较不同... 相似文献
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泰勒反应器中的波状涡流因存在周向波和涡间传质而受到广泛关注。本文针对泰勒反应器(半径比为0.83,纵横比为46.07)中的波状涡流进行了数值模拟研究,采用计算流体力学(CFD)软件研究了无轴向流动和有轴向流动时的两种流场。结果表明,数值模拟与文献中的PIV实验结果具有较好的一致性。在波状涡流场中,周向波动的存在消除了涡的轴对称性,导致涡随周向位置的周期性变化,包括涡的形状、位置以及涡量等,这也引起了速度的瞬态行为。轴流的引入降低了涡的周期性变化程度,改变了速度的瞬时特性,也稳定了流场。同时还发现轴向流动也影响着切向速度随时间的变化,切向速度随漩涡通过频率及其高次谐波而振荡。 相似文献
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Micromixing in the submerged circulative impinging stream reactor (SCISR) developed by the authors is investigated with the Bourne's reaction scheme. The values measured for the impinging velocity, u0, under the conditions of SCISR normal operation, only is of the order of 0.1m·s-1, are much slower than that inferred, suggesting low power requirement for operation. The values of the characteristic time constant for micromixing, tM, determined in the impinging velocity range of 0.184m·s-1 相似文献
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污泥分级分相厌氧反应器水力特性研究 总被引:1,自引:0,他引:1
污泥厌氧生物反应器的结构决定了反应器的流态,从而影响着可能达到的污泥处理效率.为了提高石化水厂剩余污泥的厌氧消化效率,对一种新型的污泥分级分相厌氧反应器的结构进行了优化设计.采用停留时间分布RTD(residence time distribution)的方法研究了反应器的降流区、升流区面积之比、溢流板高度和水力停留时间等参数和反应器水力特性之间的关系.结果表明,分级分相反应器的死区较小(7.51%),远低于传统单级厌氧生物反应器(50%~93%);该反应器流态处于平推流和完全混合之间;降流区、升流区面积之比最佳值为1:2,溢流板高度为450 mm时死区最小;在平均污泥浓度为25 gVSS?L?1的条件下,最佳水力停留时间为24 h. 相似文献
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利用平面激光诱导荧光(PLIF)技术和酚酞显色反应,对不同Reynolds数(20<Re<420)下T型反应器内的复杂流动结构及界面反应进行了可视化研究。随着入口Re的增加,反应器内依次出现分离流、稳态吞噬流、非稳态吞噬流及非稳态对称流等流动模式。重点考察了不同流动模式下T型反应器内的界面反应特征,结合流动模式对混合效果、产物浓度分布及时间演化进行了分析,揭示了反应器内复杂流场对混合及界面反应的影响机理。结果表明,吞噬流三维旋涡结构使流体相互卷吸缠绕,通过折叠拉伸形成层状的流体界面,极大增加了反应物的界面接触面积,混合及反应程度显著提升,产物浓度较高且分布均匀。 相似文献
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Baldassarre Venezia David C. Morris Asterios Gavriilidis 《American Institute of Chemical Engineers》2023,69(3):e17880
A unique Taylor-vortex membrane reactor (TVMR) design for continuous gas-liquid reactions is presented in this work. The reactor consists of a cylindrical rotor inside a stationary concentric cylindrical vessel, and a flexible system of equispaced baffle rings surrounding the rotor. This restricts the annular cross section to a small gap between the baffles and the rotor, and divides the annulus into 18 mixing zones. The baffles support a 6 m long PFA tubular membrane that is woven around the rotor. At 4 mL/min inlet flow rate, the TVMR showed a plug-flow behavior and outperformed the unbaffled reactor, having 5–12 times lower axial dispersion. The continuous aerobic oxidation of benzyl alcohol was performed for 7 h using the Pd(OAc)2/pyridine catalyst in toluene at 100 °C and 1.1 MPa oxygen pressure. A stable conversion of 30% was achieved with 85% benzaldehyde selectivity, and no pervaporation of organics into the gas phase. 相似文献
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Effect of the rotor shape on the mixing characteristics of a continuous flow Taylor-vortex reactor 总被引:1,自引:0,他引:1
Oliver Richter 《Chemical engineering science》2008,63(13):3504-3513
Macro- and micromixing in a continuous flow Taylor-vortex reactor with novel ribbed rotors were investigated and compared to the features of a classical cylindrical rotor. The characterisation was performed in a wide hydrodynamic range (40<Ta<2500 and 0.03<Re<0.51) through tracer experiments and the analysis of the rotor power consumption. Additionally, the flow patterns were visualised by using a rheoscopic fluid. The results show that the novel rotors equipped with ribs immobilise and stabilise the vortices. As compared to cylindrical rotors, micromixing is clearly enhanced while axial dispersion can be simultaneously reduced. Through the use of ribbed rotors, the operational window can be broadened considerably, in which the reactor runs at very low or moderate extent of macromixing. 相似文献
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The effect of the geometrical and operational parameters on the mixing characteristics of a Couette–Taylor vortex flow reactor (CTVFR) were investigated and were correlated with the same parameters by using the tank‐in‐series model. Continuous emulsion polymerization of styrene was conducted at 50°C in a CTVFR to clarify the effects on kinetic behavior and reactor performance of operational parameters such as rotational speed of inner cylinder (Taylor number), reactor mean residence time, and emulsifier and initiator concentrations in the feed streams. It was found that steady‐state monomer conversion and particle number could be freely varied only by varying the Taylor number. In order to explain the observed kinetic behavior of this polymerization system, a mathematical model was developed by combining the empirical correlation of the mixing characteristics of a CTVFR and a previously proposed kinetic model for the continuous emulsion polymerization of styrene in continuous stirred tank reactors connected in series (CSTRs). On the basis of these experimental results, it was concluded that a CTVFR is suitable for the first reactor (prereactor) of a continuous emulsion polymerization reactor system. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1931–1942, 2001 相似文献
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The scope of this paper is to present a theoretical study of a catalytic polymeric dense membrane reactor (CPDMR) assuming isothermal conditions, plug flow pattern without pressure drop in both retentate and permeate sides, shell side feed and cocurrent operation. The conversion enhancement over the thermodynamic equilibrium value is studied for a gas-phase reaction of the type aAbB, considering two different stoichiometric ratios: Δn > 0 and Δn < 0, where Δn = b − a. For each of these cases, the influence of the relative sorption and diffusivity of the reaction species is studied. It is concluded that the conversion of a reversible reaction can be significantly enhanced when the diffusivity of the reaction products is higher than that of the reactants and/or the sorption is lower. It is also concluded that, even for equal sorption and diffusion coefficients, the conversion could also be improved for reactions with Δn ≠ 0. The extension of this enhancement depends on the reaction stoichiometry, the overall concentration inside the membrane, the Thiele modulus, and the contact time. 相似文献