Homogeneous Laboratory Reactors

It is a good idea to run the laboratory reactor without catalyst to check for homogeneous reactions. However, this method does not work when the homogeneous reaction involves reactants that do not occur in the feed but are created by a heterogeneous reaction. It then becomes important to maintain the same ratio of free volume to catalyst volume in the laboratory reactor used for intrinsic kinetic studies as in the pilot or production reactors. 

A laboratory reactor system was constructed for the investigation of tar conversion under real fixed-bed conditions. The basic idea behind the reactor design was the spatial separation of primary pyrolysis and secondary tar reactions. A scheme of the system is shown in fig, 2. After the primary pyrolysis stage, the tar containing pyrolysis gas is swept to the conversion reactors where homogeneous and/or heterogeneous tar reactions can be investigated. 

Although our major interest in this chapter is heterogeneous laboratory reactors, for the sake of completeness we shall briefly review homogeneous systems. Experimental measurements in homogeneous reactors represent... 

In conclusion, a few comments about the practical importance of heterogeneous-homogeneous reactions from kinetic viewpoint. Usually industrial reactors have a relatively large free volume and the packing material is also present in addition to the catalyst. If homogeneous reactions are beneficial for the overall process, then they will be retarded due to deactivation of radicals and the rate will be lower compared to laboratory reactors with more advantageous reactor geometries. 

Figure 4.14 Main types of laboratory reactors for studying various homogeneous and heterogeneous reactions. RDC = rotating disk contactor.

Figure 7.2 Alternative configurations of batch laboratory reactors to obtain kinetic data, mainly from homogeneous mixtures, (a) Round-bottomed flask in a heating mantle, (b) ampules in a thermostat, (c) small bench-scale reactor in a thermostat, (d) boat containing liquid reactant in a furnace with or without a flowing gaseous reactant, (e) reactor with provision for measuring evolving gas, (f) mixed microreactor, (g) calorimetric reactor, and (h) output from calorimetric reactor. 1, Removable lid 2, thermal buffer zone 3, heating elements 4, thermopiles 5, experimental area 6, calorimetric block 7, insulation layers and 8, cooling circuit.

Different laboratory reactors are used for kinetic studies. For studies of liquid-liquid reactions and homogeneously catalyzed reactions, a batchwise operated stirred tank reactor is frequently used. Tubular reactors loaded with catalyst (fixed bed) are more common for studies of heterogeneously catalyzed gas reactions. The tubular reactor displays a simple design and is easy to operate. A simultaneous integral and differential mode of operation can be achieved by a tap reactor for measuring concentration and temperatures at defined axial positions. Gradientless operation with respect to temperature and concentration can be obtained by an external or internal recycle. 

P. R. Kasten et al.,. Aqueous Homogeneous Research Reactor-Feasibility Study, USAEC Report ORNL-2256, Oak Ridge National Laboratory, April 1957. 

L. G. Alexander and S. JaVe,. 4 Parametric Study of Rate of Power Removal from Homogeneous Boiling Reactors, US.AEC Report CF-55-9-172, Oak Ridge National Laboratory, 1955. 

R. J. Rickert et al.,. 4 Preliminary Design Study of a lO-Mw Homogeneous Boiling Reactor Power Package for use in Remote Locations, USAEC Report CF-53-10-23, Oak Ridge National Laboratory, 1953. 

C. H. Secoy et al., in Homogeneous Reactor Project Quarterly Progress Report for the Period Ending July SI, 1957, USAEC Report ORNL-2379, Oak Ridge National Laboratory, Oct. 10, 1957 (p. 163) F. Moseley, Core Solution Stability in the Homogeneous Aqiieous Reactor The Effect of Corrosion Product and Copper Concentrations, Report HARD(C)/P-41, Gt. Brit. Atomic Energy Research Establishment, May 1957. 

R. B. Briggs and J. A. Swartout, Aqueous Homogeneous Power Reactors, in Proceedings of the International Conference on the Peaceful Uses of Atomic Energy, Vol. 3. New York United Nations, 1956 (p. 175). S. E. Beall and S. VisNER, Oak Ridge National Laboratory, 1955. Unpublished. 

One-region solution reactors, typified by the Wolverine Reactor Study, the Oak Ridge National Laboratory Homogeneous Research Reactor, and the Aeronutronic Advanced Engineering Test Reactor. 

CHRr.sTY, R. F., Theoretical Discussion of a Small Homogeneous Enriched Reactor, USAEC Report MDDC-72, Los Alamos Scientific Laboratory,. June 18, 1946. 

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