On the preparation of energy balances
for brick and tile-making plants (Part 2)

This tripartite article describes the basic theory and practice of preparing energy and mass balances for dryers and kilns in the brick and tile industry. The criteria to be met by the requisite test instruments are described, as are the available software solutions for use in generating energy balances. Special attention is devoted to methods applied for checking the plausibility of such balances. Part 3 will appear in the next issue of Zi Brick and Tile Industry International.

7 Calculating the heats of vaporization and reaction

The heat of water vaporization depends on the temperature of the green bricks at the entrance to the dryer or kiln. At 0° C, it amounts to 2500 kJ/kg, and it reaches 0 kJ/kg at the critical temperature of 374.2° C (»6). For temperatures between 0° C and 100° C, the specific heat of water vaporization ∆HR, W can be approximated using the following equation:
∆HR, W = 2 500 – 2.41 · qB(18)
In the energy balance of the dryer, the thusly calculated heat of reaction ∆HR directly corresponds to the balance item heat of vaporization (»4).

During heatup...

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