PFTR Multiple Hearth

Phases Gas plus reactant solid. Regeneration of adsorbents, catalysts, incineration of sludges, reduction of ores and roasting of some solids. Capacity about 0.01-10 kg/s solid particle diameter 0.2-20 mm. Temperatures for incineration in the range 790-980 °C. 

Solid residence time, 5000-30000 s usually 15 000-18000. Hot combustion gas flows over the solids. Solids loading 1.25 to 2 g/s rrf of single hearth or 2 to 20 g/s m of total hearth. 

The effective hearth area is 42-62 % of nominal area calculated from the overall OD with the higher % referring to larger diameter hearths. For fast reactions, bulk phase film diffusion may control and pore diffusion may control if the solid diameter 1.5 mm. 

The heat load is 150-250 kW/m with the usual design capacity about 7 MW. Incineration heat release from combustion 150-250 kW/m.  

Reactors solids residence time 4-5 h. For direct reduced iron, bed height of pellets, 

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