CRITERIA FOR GRADIENTLESS OPERATION OF INTERNAL RECYCLE REACTORS

The recycle flow rate of an internal recycle reactor was determined for the endothermic methanol-steam reforming reaction over Cu/ZnO/Al2O3 by axial temperature measurements. The experimental parameters were varied within the ranges: pressure(0.1 - 1.4 MPa), impeller frequency (8.3 - 41.7 s-1), catalyst weight (3 - 30.10(-3)kg) and particle size (0.6 - 5.5.10(-3)m). The studies indicate that a generally valid relationship can be given which describes the flow characteristic within this parameter field. A new 'recycle efficiency' factor was introduced to quantify the influences of axial and interparticle gradients. The validity of this concept was tested by experiments performed under constant concentrations but different stirrer frequencies. Known criteria for gradientless operation are critically discussed.