STUDY ON EMISSION OF HEAVY METALS FROM THE COAL-FIRED INDUSTRIAL BOILERS

The concentration of heavy metals in the flue gas before and after 6 sets of typical pollution control system of coalfired industrial boilers were tested，and the removal efficiencies of the electrostatic precipitator ( ESP) ，wet flue gas desulfurization ( WFGD) system and the integrated desulfurization and dust removal unit on the heavy metals in flue gas were also studied． ESP shows great performance in heavy metals removal，and the efficiency of more than 50% can be attained for Pb，Cd and Cr． And as for Hg removal process of ESP of the No. 1 and No. 2 industrial boilers，the efficiencies are 45. 70% and 29. 63%，respectively． The concentrations of Hg，Pb and Cd are less than 10 μg /m3 in the outlet of WFGD system． The integrated desulfurization and dust removal unit slightly influences the removal efficiency of Hg，Pb and Cd，and the Pb emission concentration after the No. 4 industrial cleaning unit is as high as 65. 76 μg /m3 ． The heavy metals removal capacities for the ESP + WFGD are higher than that of the integrated desulfurization and dust removal unit．