TGA-based kinetic parameters and laboratory-scale pyrolysis of Northeastern Indian coals
摘要
The current work aims to study the kinetics of Northeastern Indian coals using non-isothermal thermogravimetric data. An investigation was conducted on the laboratory-scale pyrolysis of Northeastern Indian coals using a fixed-bed reactor to analyse product distribution and characterisation. The coal samples were procured from Bokolia, Assam (AB), Margherita Coalfield, Assam (MG), and Bapung of Jaintia Hills, Meghalaya (MB). The physicochemical characteristics of all three coals were studied. The AB coal was found to be of lignite grade, and the other two were sub-bituminous. The thermal degradation behaviour of the coal samples was investigated under inert conditions by thermogravimetric analysis (TGA). Powder samples (100 mesh) were subjected to TGA analysis in the temperature range of 293–1273 K at heating rates of 10, 20, 30, and 50 K min−1. Mass loss plots from TGA were employed for determining kinetic parameters using iso-conversational methods: differential Friedman, Starink, Kissinger–Akahira–Sunose (KAS), Ozawa–Flynn–Wall (OFW), and distributed activation energy (DAE) method. The corresponding activation energy values and pre-exponential factor values were determined for all three samples. Criado’s master plots were used to establish possible thermal degradation mechanisms. The acquired kinetic triplets were used to reconstruct the conversion profiles to develop and select the pertinent model. Further, laboratory-scale pyrolysis experiments were performed with 30 gm powder samples at two isothermal temperatures, 723 and 873 K (10 K min–1 heating rate), for 2 h of retention time in a fixed-bed semi-batch reactor. The products obtained were characterised for compositional analyses using FESEM, FTIR, 1H NMR, GC-TCD/FID/PFPD, and GC–MS. Understanding the kinetics and pyrolysis products of coal will be beneficial for developing various clean coal technologies.