Article ID Journal Published Year Pages File Type
205459 Fuel 2015 12 Pages PDF
Abstract

•Phase equilibria of the coal–petcoke gasifier slags were experimentally studied.•CaO and FeO increased the liquid slag phase field in compositions studied.•The mullite crystal formation was suppressed in slags with >9 wt.% FeO.•Karelianite precipitates were present if slag contained >2 wt.% V2O3.•Isothermal phase diagrams at 1500 °C in 10−8 atm Po2 were constructed.

Thermodynamic phase equilibria in synthetic slags (Al2O3–CaO–FeO–SiO2–V2O3) were investigated with 0–27 wt.% vanadium oxide corresponding to industrial coal–petroleum coke (petcoke) feedstock blends in a simulated gasifier environment. Samples encompassing coal–petcoke mixed slag compositions were equilibrated at 1500 °C in a 64 vol.% CO/36 vol.% CO2 atmosphere (Po2 ≈ 10−8 atm at 1500 °C) for 72 h, followed by rapid water quench, then analyzed by inductively coupled plasma optical emission spectrometry, X-ray diffractometry, and scanning electron microscopy with wavelength dispersive spectroscopy. With increasing CaO content, FeO content, or both; the slag homogeneity region expanded and a composition range exhibiting crystals was reduced. The mullite (Al6Si2O13) crystalline phase was not present in the slags above 9 wt.% FeO while the karelianite (V2O3) crystalline phase was always present in compositions studied if a sufficient amount of vanadium existed in the slag. Based on the present experimental equilibrium evaluation, a set of isothermal phase diagrams showing effects of CaO and FeO on thermodynamic phase stabilities in the vanadium-bearing slags is proposed. Some uses of the diagrams for potential industrial practice are discussed.

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Physical Sciences and Engineering Chemical Engineering Chemical Engineering (General)
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