Refractory damage

Semler, C.E., Hawisher, T.H. and Bradt, R.C., Thermal shock of alumina refractories damage-resistance parameters and the ribbon test , Am. Ceram. Soc. Bull., 1981 60(7) 724-9. 

Even on relatively new units, refractory damage and evidence of overheating are visible. 

No negative effects were noted on the refractory. After an initial 3 month startup period, the furnace was cooled down and the internals were inspected, with no refractory damage noted. It was even possible to reduce the furnace temperature set point after optimizing the charging and melting practice. Overall, the roof temperature was lowered by 100°F (56°C), while maintaining the 30% increase in melt rate. This reduction was expected to result in considerable savings in refractory expenses. 

Materials for refractory lining are chosen based on several factors, including their stability and durability. While the main intention is to protect the steel shell, they can serve as an insulation material necessary to retain the heat within the kiln interior. At the sections near the combustion zone, conductive materials are preferred for lining so as to dissipate some heat away and prevent excessive temperature build-up and thereby avoid thermal stresses and associated refractory damage. Lining materials come in all forms including bricks and mortars of all consistency that can be spread or sprayed on surfaces. The material composition and thermo-physical properties of some lining materials are presented in Table 7.1. 

Byproduct Coke Oven Battery Heating Wall Refractories—Damage and Causes of Failure... 

Control of pollutants by oxidation is another exothermic process in which high conversion is the most important performance criterion. Interest in efficiency is limited to minimize byproduct formation the byproducts can be more damaging and more refractory than the original pollutants were. Commercially, most adiabatic reactors used for pollution control are of the least expensive construction. 

Missing or damaged refractory may permit short circuiting of flue gases and overheating. 

Barium radiography is less expensive than endoscopy but lacks the sensitivity and specificity needed to accurately determine the presence of mucosal injury or to distinguish Barrett s esophagus from esophagitis. Twenty-four-hour ambulatory pH monitoring is useful in patients who continue to have symptoms without evidence of esophageal damage, patients who are refractory to standard treatment, and patients who... 

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