The chemical thermodynamic equilibrium software FactSage was used to simulate the emission forms of trace elements(Hg

As)during oxyfuel combustion at different pressures.The results show that

during the oxygen-enriched combustion of coal

Hg exists mainly in forms of Hg(g)

HgCl_2(g)and HgO(g).Especially

Hg exists completely in form of HgCl_2(g)at 400℃and Hg(g)above 700℃.With the increasing system pressure

the temperature corresponding to the conversion range of HgCl_2(g)to Hg(g)rises

and he maximum proportion of HgO(g)increases.The As mainly exists in forms of AsO(g)

As_4O_6(g)and As_2O_5(s)

it exists completely in form of As_2O_5(s)at 500℃and AsO(g)above 800℃.As4O6(g)only exists at temperature between 500 ℃ and 800 ℃.As the system pressure increases

the conversion range temperature of As_2O_5(s)to AsO(g)rises.