Method of determining baseline heat flow in measurement of coal pyrolysis reaction heat by TG-DSC

When applied in the measurement of coal pyrolysis reaction heat,the differential scanning calorimeter outputs a total heat flow signal which is composed by reaction heat flow and baseline flow.Hence,determination of baseline heat flow is the key to accurately measuring the coal pyrolysis reaction heat.The composition of the baseline heat flow in the process of measuring pyrolysis reaction heat of coal and other heterogeneous organic matters by TG-DSC technique was theoretically analyzed in this paper,then the comparison of empirical methods with the testing approaches to determining the baseline heat flow was conducted.Finally the evaluation of the testing approaching to determining the baseline heat flow for each consisting part was carried out,in which particular attention was focused on their application possibility in the determination method of baseline heat flow.Results show that during the measurement of coal pyrolysis reaction heat by TG-DSC,the baseline heat flow consists of two parts,namely,sensible heat flow and radiation heat flow difference.On the basis of thermal analysis parameters which are obtained by TG-DSC in the measurement of coal pyrolysis reaction heat,sensible heat flow could be calculated by using Merrick model,mixture model,empirical formula of ash specific heat,etc.As for radiation heat flow difference,it could be obtained by correction factor λ after relating the process of coal pyrolysis with char pyrolysis.Finally,the baseline heat flow of coal pyrolysis reaction is determined by the sum of sensible heat and radiation heat flow difference.