Chemical Effects at the Coke-Oven Lining. 2. Reactions within the Heating System

The probability of reactions in coke batteries between the coke oven lining and components in the heating system is considered. The corresponding temperature ranges are identified. The products of thermodynamically possible reactions are FeO and Fe3O4, carbon dioxide, carbonates of calcium, sodium, and potassium (CaCO3, Na2CO3, K2CO3), and also CaSiO3, Na2SiO3, and K2SiO3. The carbon dioxide (CO2) formed in the reactions escapes with the combustion products. The melts formed always move from the heating channel to the coking chamber along the temperature gradient in the capillary system of the silica brick. The reactions that occur determine the composition and quantity of the melts that will be deposited in the slag zones at the lining surface in the furnace chamber and will then make contact with the coke. In the regenerators and floor channels, the reactions occur at the lining surface, with periodic change in the direction of melt motion as the furnace tips. Therefore, in that case, melts are only deposited in slag zones, where they modify the chemical composition of the lining and thus give rise to local defects. These lining defects are difficult to detect and even harder to eliminate. Accordingly, new diagnostic methods are under development for the state of the lining in the heating system.