Desicription：There are important advantages in oxy-fuel technology over conventional combustion, such as the reduction in fuel consumption and gaseous emissions. However,before its use in the steel industry, it is essential to know that the alteration of thefiring system can lead to an increase in the wear of the oxide-carbon refractories.
Title: Evaluation of oxidation resistance of MgO-C bricks in oxy-combustion and air-combustion
Keywords: MgO-C refractories, MgO-C brick, oxy-fuel, steelmaking ladle heating
Introduction
The steel industry continuously seeks improvements in the performance of refractory materials, fuel savings, energy efficiency developments, and the use of alternative fuels, as a way of reducing production costs and improving its competitiveness, which is very important in a market characterized by global competition. Oxy-fuel technologies are very attractive options to achieve a reduction in fuel consumption and improvements in energy efficiency. However, the wearing of oxide-carbon refractories followed by mechanical and thermal damages must also be considered. Refractories must be heated before setting into operation in a stage that causes oxidation and loss of part of the carbon and the organic binder. This can lead to a decrease in corrosion resistance and considerable wear of the refractory lining. In a study of preheating an industrial new ladle, approximately 6 mm of the refractory surface was oxidized, which may represent a reduction of 2 runs of steel production.
After testing
The MgO-C brick size was 178 mm × 100 mm × 100 mm3 (width, height and depth), and sample size was 100 × 100 × 100 mm3. In addition to the numbering, the bricks were labeled by letters, according to their position in the furnace, as shown in Figure. Bricks 1a, 2a, 3a, and 4a were located at the end of the furnace, 3 m apart from the flame. Bricks 1b, 2b, 3b, and 4b were positioned 1 m apart from the flame. Therefore, in each run, two samples of each type of brick were used, but at different locations in the furnace. We considered the sample size used as representative of an entire brick, so each piece of data was the result of a specific experiment, without repetition.
Given the size of the furnace, it is possible to simulate situations of industrial equipment such as boilers, furnaces steelmaking ladle, etc. Figure shows an external overview of the furnace and the control boards.
Conclusions
The most important factor for the use of the oxy-fuel system was the correct selection of the refractory microstructural properties, including the utilization of antioxidant additives.
