Effect of Temperature Gradient on Industrial Gasifier Coal Slag Infiltration into Alumina Refractory

Abstract

Infiltration characteristics of industrial coal slag into alumina (Al 2 O 3 ) refractory material with a temperature gradient induced along the slag's penetration direction are compared to those obtained under near-isothermal conditions. Experiments were conducted with a hot-face temperature of 1450°C and a CO/CO 2 ratio of 1.8, which corresponds to an oxygen partial pressure of~10 À8 atm. The refractory under the near-isothermal temperature profile, with higher average temperatures, demonstrated a greater penetration depth than its counterpart that was under the steeper temperature gradient. Slag that did not infiltrate into the refractory due to the induced temperature gradient, pooled and solidified on the top of the sample. Within the pool, a conglomerated mass of troilite (FeS) formed separately from the surrounding slag. Microscopy of the crosssectioned infiltrated refractories revealed that the slag preferentially corroded the matrix regions closer to the top surface. Furthermore, the formation of a thick layer of hercynite (FeAl 2 O 4 ) at the top of refractory/slag interface significantly depleted the slag of its iron-oxide content with respect to its virgin composition. A qualitative description of the penetration process is provided in this article.W. Lee-contributing editor Manuscript No. 29382.

The effect of a temperature gradient on the phase formation inside a magnesia–chromite refractory in contact with a non-ferrous PbO–SiO2–MgO slag

“…In this paper a refractory sample is placed between the cooling probe and the liquid slag bath, thereby creating a temperature gradient over the refractory sample. This approach differs from the experimental setup currently used by Kaneko et al [12][13][14] where a refractory sample is partially put in the hot zone of a furnace while the bottom of the refractory is kept in a colder part of the furnace resulting in a temperature gradient over the sample. A hole is drilled in the part of the sample in the hot zone and filled with slag.…”

Slag Behavior in Gasifiers. Part I: Influence of Coal Properties and Gasification Conditions

“…All these difficulties can be overcome by adding more oxygen to the gasifier in order to burn more coal and generate more heat. However, this reduces the overall efficiency of an IGCC system by increasing the parasitic power load of the air separation unit, reducing syngas yield, and, when a refractory-lined gasifier is used, shortening the life of the refractory [36,37]. For most coals, the ash melting point and the slag viscosity are more constraining than the carbon conversion considerations; therefore, the operating temperature of the gasifier is selected based on the ash slagging temperature or the ash flow temperature and the slag viscosity [9]-characteristics that are important for selecting the appropriate operating temperature of the gasifier to avoid either overfiring or solidifying the slag inside the gasifier.…”

Degradation mechanism of Cr2O3‐Al2O3‐ZrO2 refractories in a coal‐water slurry gasifier: Role of stress cracks

“…A deeper understanding of corrosion behavior/mechanism is vital to the prediction of the stability, reliability and overall service performance of chromite containing refractories. To date, the corrosion behaviors of chromite‐containing refractories in gasifiers have been investigated under some specific conditions . It should be pointed out that the degradation of refractories in a commercial gasifier is resulted from, and thus dependent upon, the synergistic attack from several processing parameters, for example, high pressure/temperature, mechanical failure, complex atmosphere, and prolonged testing time.…”