Design of venturi loop reactor

The ejector is at the heart of the venturi loop system. Therefore, a discussion on the design of the latter needs to include the information available on design of ejectors, the related hydrodynamics, and mass transfer parameters. This section reviews the same and makes recommendations regarding configuration of the venturi section in relation to the entire system. 

There is considerable information available in the hterature on the design of ejectors (steam jet ejectors, water jet pumps, air injectors, etc.) supported by extensive experimental data. Most of this information deals with its use as an evacuator and the focus is on ejector optimization for maximizing the gas pumping efficiency. The major advantage of the venturi loop reactor is its relatively very high mass transfer coefficient due to the excellent gas-liquid contact achieved in the ejector section. Therefore, the ejector section needs careful consideration to achieve this aim. The major mass transfer parameter is the volumetric liquid side mass transfer coefficient, k a. The variables that decide k a are (i) the effective gas-hquid interfacial area, a, that is related to the gas holdup, e. The gas induction rate and the shear field generated in the ejector determine the vine of and, consequently, the value of a. (ii) the trae liquid side mass transfer coefficient, k. The mass ratio of the secondary to primary fluid in turn decides both k and a. For the venturi loop reactor the volumetric induction efficiency parameter is more relevant. This definition has a built in energy 

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Enhanced yield of cyclohexylamine Yield increased from 81% in conventional stirred reactor to 93.5% (please refer to Section 8.13, Worked Examples for Design of Venturi Loop Reactor Hydrogenation of Aniline to Cyclohexylamine) Relatively short time of 4h at a lower pressure of 2.5 MPa. Unreacted sugar as low as 0.03% Catalyst consumption reduced by 80% as compared to conventional stirred reactor... 

Batch time lowered by a factor of 2 catalyst loading reduced by factor of 2 Solventless system increases productivity as compared to conventional stirred tank reactor. Reaction time reduced by 80% yield increased from 83 to 94% Appropriate design of venturi loop reactor reduces chlorination batch time by a factor of 5-7 from 20 to 40 h required in a conventional stirred tank reactor. Highly efficient heat transfer in the external loop affords nearly isothermal operation at 45-50 °C, resulting in a high yield (more than 90%) of 2,4-dichloro phenol while suppressing formation of 2,6 dichloro phenol. Efficient removal of reaction by-product (hydrogen chloride) in the external gas circuit (Fig. 8.3) improves the yield Almost complete conversion of methanol in less than 1 h... 

WORKED EXAMPLES FOR DESIGN OF VENTURI LOOP REACTOR HYDROGENATION OF ANILINE TO... 

Calculations for design of venturi loop reactor for manufacturing of 25,000 metric tonnes per year of cyclohexylamine by hydrogenation of aniline are presented in a separate Excel file. This file works in all Excel versions of Microsoft Office Excel 97-2003 and higher. 

However, if this same reaction is carried out in a venturi loop reactor, the order of magnitude large values of k a in the venturi section is likely to result in a situation such that Equation 2.6 is valid. Consequently, the mass transfer limitation can be eliminated when the venturi loop reactor replaces the stirred tank type. Thus, the reaction can achieve the maximum intrinsic rate or operate at the maximum possible capacity. This matter has been briefly discussed in Section 3.4.2.4 for Uquid-phase oxidation of substituted benzenes. The solved reactor design problem in Section 8.13 shows that this is indeed the case for catalytic hydrogenation of aniline to cyclohexylamine. 

The rate of gas induction is decided by the type of impeller used, the design of the stator, the speed of the impeller, and the static head above the gas ports. Analogous to the venturi loop reactor (Sections 8.6 and 8.7), the rate of gas induction cannot be varied independent of the aforementioned design and operating features. However, in the present case of gas-inducing impeller, in the event that the induced... 

S.4.2.2 The Advanced Buss Loop Reactor (ABLR) This reactor has been described in detail by Baier (2(X)1). This unit includes two major modifications of the previous version termed BLR . A shorter venturi without a diffuser or draft tube has replaced the relatively long prior design. In this form, the combination of primary... 

Gas sparged chemical reactors are designed and used in many different geometries. These reactors are usually continuous in gas, and batch or continuous in liquid. Some of the geometries in use are bubble columns, pipe and static mixer reactors, stirred vessels, packed columns, tray columns, spray columns, jet loop reactors, and venturi ejector reactors. Design equations for each geometry are based on correlations and simpUfying assumptions, such as uniform kLa in the stirred vessel. Other gas-Uquid reactors include spray columns and spray combustors. 

Gourich B, El Azher N, Vial Ch, Belhaj Soulami M, Ziyad M, Zoulalian A. (2007) Influence of operating conditions and design parameters on hydrodynamics and mass transfer in an emulsion loop-venturi reactor. Chem. Eng. and Process., 46 139-149. 

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