The lignite was pyrolyzed in a tube furnace at medium-low temperature between 500℃and 650℃

then the combustion characteristics of the lignite semicoke was analyzed by thermal analysis method.The effects of pyrolysis temperature and holding time on yield

composition and calorific value of the semicoke were investigated.Moreover

the combustion dynamics of the coal samples was studied by the Coats-Redfern integration method

on the basis of the thermogravimetric experiment.The results show that the holding time has no obvious influence on yield

composition

calorific value and combustion characteristics of the lignite semicoke

while the pyrolysis temperature has a great one.After paralysis

the coal rank of the semicoke increased.With an increase in pyrolysis temperature

the C/O ratio

fixed carbon content

ash content and calorific value of semicoke increase

while the yield and volatile content of the semicoke decrease.High temperature makes the combustion characteristics of semicoke be worse and the coal rank tend to be higher.The results indicate that the reaction order model(n=7/6)can be adopted to describe the lignite semicoke combustion.With the increase of pyrolysis temperature and holding time

the reaction reactivity of semicoke decreases while activation energy increases

the activation energy changes within the range from 78.1kJ/mol to 116.4kJ/mol.