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

Abstract

Durability and corrosion behavior of refractory lining, a core part of a commercial water‐coal slurry gasifier, largely determine its gas yield rate and carbon conversion rate. In this work, corrosion behavior of high chromite‐containing refractory served for 4200 hours in a water‐coal slurry gasifier was studied, and the role of generated stress cracks on its degradation behavior was elucidated. The results demonstrated that the depth of penetration under the assistance of the cracks was up to 2.60 cm, which was much deeper than that in the case free from stress crack. The sub‐surface, accompanied by cracking, provided a pathway for slag penetration and resulted in more severe corrosion. Furthermore, the isolation layer of (Cr, Fe, Al)2O3 solid solution on the refractory’ surface trapped most of the iron oxides. As a result, a further attack from other main corrosive species was controlled by their diffusion through it.

Oxidation behaviors of low carbon MgO‐C refractories: Roles of Ti2AlC and Ti2AlN

“…Following oxidation testing, the oxidized samples were examined using microfocus X-ray CT (Phoenix v|tome|x s, GE Inspection Technologies, GmbH, Germany). 37,38 Then, the cylindrical samples were sectioned perpendicular to the cross-section using a cutting machine to count the oxidation area. Phase evolutions after oxidation were identified by X-ray diffraction (XRD; Bruker D8 Advance; using Ni-filtered, Cu Kα radiation), and microstructural observation were conducted using a field SEM (Nova 400 Nano-SEM, FEI Company, USA) equipped with an EDS instrument (INCA IE 350 PentaFET X-3, Oxford, UK).…”

“…The oxidation processes were performed at target temperatures (1100 and 1500°C) and held for 180 min at a 5 K/min rising rate during the heating process. Following oxidation testing, the oxidized samples were examined using microfocus X‐ray CT (Phoenix v|tome|x s, GE Inspection Technologies, GmbH, Germany) 37,38 . Then, the cylindrical samples were sectioned perpendicular to the cross‐section using a cutting machine to count the oxidation area.…”

Glass-contact refractory of the nuclear waste vitrification melters in the United States: a review of corrosion data and melter life

“…Upward drilling occurs where a downward-facing refractory surface is in contact with gas bubbles trapped against it and takes place where open pores or cracks form in the refractory lining surface [68,[77][78][79]. These structure anomalies include material defects introduced during the manufacturing process (casting the refractory bricks and lining the melter) such as pores, inclusions, and cracks, and the stress from thermal gradients (thermal shock) during melter operation [80,81]. Most catastrophic thermal shock effects occur during initial melter heat up and can be managed by proper control of temperature during the initial heat up.…”

Numerical Analysis of Fracture Failure Behavior of Refractory Lining in Coal-Water Slurry Gasifier

“… 32 The environment of the inner refractory layer is much more severe than that of the outer layer in the actual operation process of gasifier. The preliminary analysis shows that the hot-face brick is highly susceptible to fracture during the operation of the gasifier, and the service life is usually shorter than 5000 h, 33 while fracture failure of the outer refractory layer is negligible. The K-brick is a hot-face brick located at the uppermost part of the sidewall area in the gasifier, and its original thickness is 230 mm.…”

“…In fact, the fatigue crack growth in the hot-face brick of the coal-water slurry gasifier mainly occurs during the temperature drop after the gasifier has been stopped. 8 , 33 , 34 This is because the temperature of the hot-face brick drops faster than that of the back-up brick after the gasifier stops. This causes the cracks to be subjected to tensile stresses on both sides of the crack, resulting in crack destabilization and expansion.…”