Experimental Study On The Combustion Of Simulated Municipal Solid Wastes In A Fixed Bed

Incineration of municipal solid waste(MSW) is one of the key areas in the global cleaner energy strategy. In order to reveal the features of the combustion process of municipal solid waste, a fixed-bed reactor is employed to burn simulated municipal solid waste. Simulated municipal solid waste consists of vegetable, sand, and paper card, owning the similar ash, moisture, fixed carbon contents as real municipal solid waste. The reactor is a vertical cylindrical combustion chamber, which is suspended by a weighing scale. The height of the chamber is 1.3 m with an inner diameter of 180 mm. The grate is located at the bottom of the chamber and consisted of a perforated plate made from stainless steel, with approximately 95 holes of 7 mm diameter, representing 14.7% open area. A gas burner is placed at a 45°angle toward the waste at 740 mm above the grate. There is a gas-sampling probe inside the chamber at 390 mm above the grate and ten thermalcouples are installed along the height of bed.The effects of primary-air flow rate have been assessed over wide ranges. The temperature of different positions inside the bed, the gas species concentration of flue gas and the changing of bed weight have been measured and presented. Other parameters, such as burning rate, were also investigated and calculated from the experiment data.The results of experiment show that the burning rate increases as the airflow rate increases until a peak point is reached, beyond which further increase in the airflow rate results in a fall in the burning rate. It is also found that volatile release as well as char burning is intensified with an increase in the airflow rate until a critical point is reached, where a further increase in the airflow rate results in slowing down of the combustion process. After ignition of the bed, the CO2 concentration increases with a corresponding decrease of the O2 concentration in the bed. As the airflow rate increases, the peak concentrations of NO and CO also increase until the maximum values are reached and then fall. During the stage of stable combustion in the experiment, the mass burning rate of the sample stays constant.The effect of primary air temperature on the waste bed combustion has been studied. The results indicate that the influence of primary air temperature on the waste combustion process and NO concentration change is not very significant.Through this experimental investigation, the combustion process of simulated MSW in bed can be better understood. The results of experiment provide dependable data for design and optimization of the incinerator of MSW.