In tests discussed earlier in this Keeping Current series, coal heating has been accomplished with small sample volumes in such a way as to minimize thermal gradients. This differs from conditions present in industrial coke ovens, where heat is transmitted from heating walls toward the center of an oven containing tons of coal. The heating rate profoundly influences the devolatilization of coal, its swelling/contracting properties and thermoplasticity. Therefore, larger scale apparatus have been designed and employed in an effort to: 1.Evaluate the volume-change characteristics of coals and coal blends to assess ease of pushing coke from the ovens. 2.Measure pressure changes induced by coals on the coke oven walls during a coking cycle. 3.Obtain sufficient coke samples for the prediction of coke quality under similar conditions used during industrial coking. Although various types of apparatus have been employed to obtain these goals, only the sole-heated oven and the moveable wall test oven will be discussed.
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