Taking the demineralized Shenmu coal as samples

the influence of calcium carbonate on pyrolysis characteristic of coal was experimentally investigated on a tube furnace reactor.The pyrolysis product yields and gas component of coal samples with different amounts(0%

2%

5%

10%)of calcium carbonate were obtained

within the temperature range from 500℃to 800℃.The results show that

the calcium carbonate will react with the carboxyl in the coal

as the crossliking point

Ca will fix a few large molecule fragments

thus to increase the semi-coke yield and reduce the tar yield.At the same time

the calcium carbonate will change the pyrolysis gas components dramatically

and the influence is different at low temperatures from high temperatures.At temperature ranging from 500℃to 600℃

the calcium carbonate will enhance the precipitation of CH_4

CO_2 and light hydrocarbon gas C_2-C_3

while it has little effect on the CO production.At temperature ranging from 700℃to 800℃

the calcium carbonate decomposes and generates CaO and CO_2

the CaO promotes the production of H_2

CH_4 and light hydrocarbon gas C2-C3

while CO_2 has an inhibition effect on this process.As a result

the yields of H_2

CH_4 and light hydrocarbon gas C2-C3 nearly have no change.However

the excess CO_2 can promote the semi-coke's gasification

which sharply increase the CO yield.