Heat Transfer Problems in the Firing of Tank Blocks

JSGT 1956 V40 T260-T276

It is important to know how the temperature inside a refractory block changes when the block is fired or reheated, particularly in the case of large tank blocks for glass furnaces, but existing methods of calculation are almost impossibly tedious. The methods now described can be applied quickly and accurately to any practical case, and do not require any advanced mathematical knowledge. It is shown that when a slab is heated with a constant rate of surface temperature rise, the temperature lag at the centre of the slab ultimately becomes constant. Starting with this assumption, methods have been obtained for calculating: (1) The time during which a uniform rate of rise of surface temperature must be maintained in order to reach the above steady temperature lag at the centre, and the actual temperature lag achieved in any shorter time. (2) The temperature lag achieved in cases where the rate of rise of surface temperature is not uniform. (3) The 'soaking time' required at the end of a heating cycle, i.e. the time for which the maximum surface temperature must be held in order to allow the temperature lag to be reduced to an acceptable level. Results are given for typical cases, and the implications of these results discussed.

B. E. Moody, A. J. Madgwick & D. G. Monk