Non-mechanical valves, especially the L-valves, have been used extensively in fluidized beds and circulating fluidized beds for solids recycling or to serve as a pressure seal. Despite their widespread use, reliable characterization equations for L-valves are still not available, though design principles have been proposed by Knowlton of the Institute of Gas Technology. This paper presents a set of L-valve equations which relate the solids flow rate to the L-valve design, aeration rate, and pressure drop across the L-valve. The equations were developed by visualizing a L-valve as a pneumatically-operated pseudo-mechanical valve. The valve opening is activated pneumatically by L-valve aeration. The physical interpretation of the L-valve operation corresponds to that observed by Knowlton and other researchers, and the proposed equations correlate well with the extensive data base. The data base covers L-valve diameter from 38 mm to 152 mm for particles ranging from 175 mum to 509 mum, particle density ranging from 1230 kg m-3 to 4150 kg m-3, and shape factor ranging from 0.56 to 0.915.
