Refractory linings specific heat

A number of aspects must be taken into consideration when deciding to burn AF in a rotary kiln. Technical aspects, such as the heat value of different fuel types, are very important. A possible negative impact on both the clinker quality and refractory lining must also be taken into consideration. The refractory lifetime could be reduced. To avoid this, more heat and chemical resistant refractory materials should be installed as refractory lining on the external burner pipe. Economic aspects are also important and should always be kept in mind. The availability of different AF has to be considered, transportation and preparation expenses, the cost of specific equipment together with supplementary additions, plus the cost of emission control devices. 

In the investigation of refractory lining systems, the analysis is typically done in two stages. Stage 1 is the thermal analysis. The thermal analysis can be simply steady-state thermal analysis or a transient thermal analysis. For a steady-state thermal analysis, only the thermal material property, thermal conductivity AT, is required. For transient thermal analysis, the thermal material properties required include thermal conductivity, specific heat c and density p. In any thermal analysis other data needed are the external ambient temperatures, the emissivity of the external surfaces, the external wind velocity, and other boundary conditions data that are important to the thermal analysis. 

In order to choose a refractory or heat insulation material for a specific purpose, it is necessary to have at least two or three values of the thermal conductivity at different temperatures (e.g., at 300 and 800 °C) and to know the measurement method. The thermal conductivity measurements of the lining materials for one furnace or thermal unit preferably should be made in one laboratory by the same method. 

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