Explain why TGA is a good technique for the combustion of coal.

Rad,

TGA is an Analyser, instrument for 
"determination of Moisture,volatiles,ash,fix,carbon,LOI .."

Here are  picturse of few:

http://www.elicomarketing.com/html/Navas.htm
http://www.navas-instruments.com/TGA/TGA.html


TGA stands for THERMO-GRAVIMETRIC ANALYZER;
 
while there may a combustion of a sample, it is not really a 
a method for combustion. Goal is to measure reactivity of sample:
http://www.materials.unsw.edu.au/research/coal/co2.html

Here is a description of the procedure:

Thermogravimetric Analysis
A testing procedure in which changes in weight of a specimen are recorded as the
 specimen is heated in air or in a controlled atmosphere such as nitrogen.
http://composite.about.com/od/glossaries/l/bldef_t5543.htm

Hedgie  (rating appreciated)