Comparative Evaluation of Steam Gasification Reactivity of Indonesian Low Rank Coals

Abstract

>> Steam gasification of low rank coals is possible at relatively low temperature and low pressure, and thus shows higher efficiency compared to high rank coals. In this study, the gasification reactivity of four different Indonesian low rank coals (Samhwa, Eco, Roto, Kideco-L) was evaluated in T = 700 -800°C. The low rank coals containing 53.8 ± 3.4 wt% volatile matter in proximate analysis and 71.6 ± 1.2 wt% carbon in ultimate analysis showed comparable gasification reactivity. In addition, K2CO3 catalyst rapidly accelerated the reaction rate at 700°C, and all of the coals were converted over 90% within 1 hour. The XRD analysis showed no significant difference in carbonization between the coals, and the FT-IR spectrum showed similar functional groups except for differences due to moisture and minerals. TGA results in pyrolysis (N2) and CO2 gasification atmosphere showed very similar behavior up to 800°C regardless of the coal species, which is consistent with the steam gasification results. This confirms that the indirect evaluation of the reactivity can be made by the above instrumental analyses.

Steam Gasification of Thermally Extracted Ash-Free Coals: Reactivity Effects Due to Parent Raw Coals and Extraction Solvents

“…In addition, thermal extraction removed catalytic ashes such as Fe 2 O 3 , K 2 O, CaO, and MgO that could catalyze the gasification, possibly resulting in AFCs with decreased reactivity . Previous work also reported that 45–50% of ashes in Eco-Raw and Cyp-Raw are catalytically active minerals . Kopyscinski et al also found that AFCs were less reactive than the corresponding Raws because of negligible amounts of ash minerals in the AFCs.…”

“…38 Previous work also reported that 45−50% of ashes in Eco-Raw and Cyp-Raw are catalytically active minerals. 39 Kopyscinski et al 40 also found that AFCs were less reactive than the corresponding Raws because of negligible amounts of ash minerals in the AFCs. The highly carbonized raw HRCs (Dra-Raw and Hai-Raw) were much less reactive than the LRCs, and their reactivities were comparable to those of their AFCs.…”