Experimental investigations on novel electronic waste based oxygen carriers for direct coal fuelled chemical looping combustion process

Abstract

Electronic waste is considered as a serious global threat to the environment due to the rapid technology development and population growth. Hence, these wastes have to be used in a best way to resolve soil and air pollution issues. The printed circuit board (PCB) found in computers contains mainly metals and polymers. Copper, iron and nickel are employed in PCB boards and these components could be used as potential oxygen carriers in the chemical looping combustion (CLC) process. The present study experimentally evaluated the feasibility of utilizing PCB based oxygen carriers in the CLC process. In the first step, a series of experiments such as pyrolysis, gasification and combustion process have been performed in a fixed bed reactor using a PCB board. During the pyrolysis under N2 atmosphere, the obtained syngas possesses a calorific value of 6 and 9 MJ/m3 at 500 °C and 700 °C, respectively. The pyrolyzed residue is then gasified to convert the polymers into syngas under CO2 atmosphere and the obtained syngas is estimated with an average calorific value of 6.3 MJ/m3. In the second step, the oxidized PCB metals under air atmosphere are used to combust the coal in the CLC process with various mass ratios (fuel:metal oxides) of 1:10, 1:20, 1:30 and 1:60. In the mass ratio of 1:60, a higher char conversion of 88.2% is achieved with more than 90% gas conversion and CO2 yield. Kinetic studies are performed using a thermogravimetric analyzer (TGA) under N2 and CO2 atmosphere with PCB based oxygen carriers by employing different kinetic models.