Investigation on the effect of superheated water vapor on gas production from pyrolysis of long-flame coal

A self-developed superheated water vapor pyrolysis system was used to conduct superheated water vapor pyrolysis experiments on Tashan and Madaotou long-flame coals at 350-534 degrees C. The gas phase products were analyzed by gas chromatography. The yield and composition of gas phase pyrolysis products from two different long-flame coals were determined, and the role of superheated water vapor in the pyrolysis process was elucidated. The optimal temperature of the long-flame coal injection superheated water vapor mining technology was obtained through heat value analysis. The results showed that when the temperature of the superheated water vapor exceeded 400 degrees C, the yield and combustible components of the gas phase products rapidly increased. As such, the release rate reached 10-15 times that observed below 400 degrees C, and the components of the combustible gases, such as hydrocarbon gas and hydrogen, exceeded 80%. Superheated water vapor not only is an excellent heat and mass transfer medium, but also provides a reactant for the re-formation reaction of hydrocarbon gas. The pyrolysis of long-flame coal under superheated water vapor at 500 degrees C yielded the best economic benefits. The low calorific value of gas phase products produced via pyrolysis per ton of coal per unit time could reach 715 MJ/(t center dot h).