Experimental investigation into the incineration of wool scouring sludges in a novel rotating fluidised bed

The main purpose of this research was to investigate the possibility of inc ineration of wool scouring sludges in a novel vertical axis rotating fluidi sed bed (RFB). A small-scale RFB was designed and constructed with an inter nal diameter (ID) of 200 mm and height of 50 mm to carry out the experiment s, In phase one of the experiments, a cold rest was conducted to investigat e the fluidisation performance of the RFB, which eventually led to the opti misation of the operating parameters, i.e., sand particle size, rotation sp eed and bed loading (bed thickness) which ensures complete fluidisation and minimum particle elutriation. Sand particle size of 0.5 to 0.6 mm, rotatio n speed of 200 to 400 rpm and bed loading of 1 kg (equivalent to bed thickn ess of 27 mm) were found optimal. These information generated were useful f or the second phase of the experiments, which was the hot test, in investig ating the possibility of incinerating wool scouring sludges in the RFB. Nin e wool sludges from different process routes generated from the wool scouri ng industries were analysed for their compositions. Most of these sludges w ere highly moist, had high volatile matter and high ash content with low le vel of fixed carbon. These characteristics made incineration difficult. Hen ce, the effect of varying the moisture content, rotation speed and sludge f eed rate on the incineration of the three selected sludges were studied in the hot test. With 5% support methane, all sludges with a maximum moisture up to 70% as-received could be successfully burned in the RFB at rotating s peeds of 200 and 300 rpm. The combustion was found to be intense with a hig h efficiency due to the good turbulence and mixing in the RFB. The combusti on gases produced, i.e.. CO, CO2 and NOx were reasonably low due to the hig h combustion intensity and efficiency. To stud; the dynamics of the: bed an d freeboard region in the RFB, the velocity flow field was simulated using a computational fluid dynamics (CFD) model to generate information of the R ow pattern. The special advantages of swirling now would benefit the gas co mbustion in the RFB. The Experimental results obtained have suggested that the incineration was successful and the ash particles elutriated were line due to the good mixing and turbulence in the RFB. This also reflects the RF B as an effective incinerator. (C) 2000 Elsevier Science B.V. All rights re served.