The experiment was conducted in a 220 MW cogeneration boiler in Beijing. The Dekati Gravimetric Impacter system was used to sample particulate matter (PM) at the inlets of selective catalytic reduction (SCR)

electrostatic precipitation (ESP) and flue gas desulfurization (FGD) in this boiler

to investigate the migration characteristics of trace elements in the flue gas tunnel. In addition

distribution of trace elements in solid combustion residues was also studied. The concentrations of As

Cd

Cr and Pb in PM at the inlet of ESP were obviously higher than those at the inlet of SCR. The masses of gaseous As

Cd

Cr and Pb converted to solid in the process of flue gas flow from SCR to ESP accounted for 26%

16%

12%

11% of the total masses in coal respectively. In the process of flue gas flow from ESP to FGD

the concentrations of As and Cd in PM slightly increased

while those of Cr and Pb were almost constant. The concentrations of Mn at the three sampling sites were almost the same. Most trace elements remained in the fly ash collected by ESP

and at the outlet of ESP

the masses of As

Cd

Cr and Pb in the four size segments with size <10 μm increased with decreasing particle size

however

mass distribution of Mn was similar with that of PM.