Abstract
Abstract Thermoanalysis was used in this research to produce a comparative study on the combustion and gasification characteristics of semi-coke prepared under pyrolytic atmospheres rich in CH4 and H2 at different proportions. Distinctions of different semi-coke in terms of carbon chemical structure, functional groups, and micropore structure were examined. The results indicated that adding some reducing gases during pyrolysis could inhibit semi-coke reactivity, the inhibitory effect of the composite gas of H2 and CH4 was the most observable, and the effect of H2 was higher than that of CH4; moreover, increasing the proportion of reducing gas increased its inhibitory effect. X-ray diffractometer and Fourier-transform infrared spectrometer results indicated that adding reducing gases in the atmosphere elevated the disordering degree of carbon microcrystalline structures, boosted the removal of hydroxyl- and oxygen-containing functional groups, decreased the unsaturated side chains, and improved condensation degree of macromolecular networks. The nitrogen adsorption experiment revealed that the types of pore structure of semi-coke are mainly micropore and mesopore, and the influence of pyrolytic atmosphere on micropores was not of strong regularity but could inhibit mesopore development. Aromatic lamellar stack height of semi-coke, specific surface area of mesopore, and pore volume had a favorable linear correlation with semi-coke reactivity indexes.
Highlights
Low-temperature pyrolytic semi-coke is a solid product after removing a number of volatiles from low-rank coal under low-temperature pyrolysis (500–600°C) and tar is separated out [1,2]
Thermoanalysis was applied to comparatively study the combustion and gasification reactivity of semi-coke prepared under pyrolytic atmospheres containing different proportions of H2- and CH4-reducing gases
To compare the semi-coke combustion reactivity values, the six curves were analyzed through combustion reactivity indexes in Eq 1
Summary
Low-temperature pyrolytic semi-coke is a solid product after removing a number of volatiles from low-rank coal under low-temperature pyrolysis (500–600°C) and tar is separated out [1,2]. Part of this product has been applied to fields like coal gasification, ferroalloy smelting, and calcium carbide production; there is still a large quantity of semi-coke resources that require market consumption. Using low price semi-coke as PCI fuel to replace expensive anthracite has been an important research orientation for optimizing blast furnace fuel structures, and the reduced production cost has attracted attention from metallurgists [7,8,9,10,11].
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