Study on structural properties of semi-coke from pulverize coal pyrolysis and influencing factors during its thermal transportation process

The thermal transportation of pulverized semi-coke is a critical link of pulverized coal pyrolysis and downstream application technology. In this work, the semi-coke powder stably produced in an industrial test device was used as the raw material, and the properties and influencing factors during thermal transportation process were researched. In comparison with feed coal, the total moisture of semi-coke decreased to 1.5%, the calorific value increased to 29.80MJ/kg, and the combustion performance parameters were similar, which made it a high quality fuel. The characterization results indicated that the surface of semi-coke was attached by a large amount of volatile matter, and it had a similar particle size and a more concentrated distribution, as well as higher degree of aromatization. The thermo gravimetric analysis and tube furnace test presented that the oxidative combustion intensity of semi-coke increased with the growth of specific contact area, temperature and oxygen concentration. Pulverized semi-coke started oxidative combustion above 350 °C at air atmosphere, and at a constant temperature of 350 °C, significant oxidative combustion occurred when the oxygen concentration exceeded 10%.