Basic Data
A model for gasification is only as good as the basic thermodynamic data used. To ensure consistency of mass and heat balances it is of fundamental importance to limit the data set to a minimum and generate all other data from this.
In the calculations used in this book and in the website programs, use has been made of various sources, the most important being Barin (1989). For the thermodynamic calculations standard enthalpy and entropy data have been used in combination with a curve-fit for the temperature dependence of the specific heat for each type of molecule.
For the moisture-and-ash-free (maf) coal the default coefficients in the formula giving the temperature dependence of the specific heat have been based on graphite.
For the ash temperature dependence the default coefficients in the formula giving the temperature dependence of the specific heat have been based on an average ash in which the heat of fusion has been taken into account. In the case where the ash and/or the fluxing agent added to the ash to lower the melting point contain carbonates, the heat of decomposition may have to be taken into account. The easiest way to do this, though, is to calculate the heat required and put it into the calculations as an additional heat loss from the gasifier.
Where alternative data, in particular for coal and ash, are desired, it would be necessary to modify this appropriate data. In the case of gasify. exe, this would need to be done in the source code.
