Study on the slurry characteristics and combustion mechanism of modified coal gasification fine slag-coal water slurry

Abstract

In this study, carbon-rich gasification fine slag (RCGFS) was modified using emulsified asphalt (EA) to produce modified RCGFS (MRCGFS), which was used to prepare carbon-rich gasification fine slag-coal water slurry (MRCGFS-CWS). Concurrently, the slurry formation properties and mechanisms were investigated, and the influence of RCGFS and MRCGFS on the combustion performance of the slurry was also examined. The results indicated that the maximum solid content of MRCGFS-CWS was 61.4 %, representing a 1.0 % increase compared to the carbon-rich gasification fine slag-coal water slurry (RCGFS-CWS), suggesting that modification enhanced the solid loading capacity of slurry. However, the maximum solid contents of both RCGFS-CWS and MRCGFS-CWS were lower than CWS. This may be attributed to the stronger hydrophilicity of RCGFS and MRCGFS than that of coal, which makes the particles more prone to agglomeration. The contact angle increased from 31.5° to 44.5° after modification, confirming enhanced hydrophobicity and improved slurry formation. The comprehensive combustion characteristic index S of MRCGFS-CWS increased from 3.76×10 -11 % 2 ·s -2 ·℃ -3 to 4.05×10 -11 % 2 ·s -2 ·℃ -3 , indicating improved overall combustion performance. Combustion kinetic studies indicated that the activation energies for RCGFS-CWS and MRCGFS-CWS were 71.57 and 92.03 kJ·mol −1 . Furthermore, all three slurries followed a second-order (F2) reaction mechanism.