Mercury emission and speciation of coal-fired power plants in China

Abstract

Abstract.Comprehensive field measurements are needed to understand the mercury emissions from Chinese power plants and to improve the accuracy of emission inventories. Characterization of mercury emissions and their behavior were measured in six typical coal-fired power plants in China. During the tests, the flue gas was sampled simultaneously at inlet and outlet of Selective Catalytic Reduction (SCR), electrostatic precipitators (ESP), and flue gas desulfurization (FGD) using the Ontario Hydro Method (OHM). The pulverized coal, bottom ash, fly ash and gypsum were also sampled in the field. Mercury concentrations in coal burned in the measured power plants ranged from 17 to 385 µg/kg. The mercury mass balances for the six power plants varied from 87 to 116% of the input coal mercury for the whole system. The total mercury concentrations in the flue gas from boilers were at the range of 1.92-27.15 µg/m 3 , which were significantly related to the mercury contents in burned coal. The mercury speciation in flue gas right after the boiler is influenced by the contents of halogen, mercury, and ash in the burned coal. The average mercury removal efficiencies of ESP, ESP plus wet FGD, and ESP plus dry FGD-FF systems were 24%, 73% and 66%, respectively, which were similar to the average removal efficiencies of pollution control device systems in other countries such as US, Japan and South Korea. The SCR system oxidized 16% elemental mercury and reduced about 32% of total mercury. Elemental mercury, accounting for 66-94% of total mercury, was the dominant species emitted to the atmosphere. The mercury emission factor was also calculated for each power plant.

Nanosized Cation-Deficient Fe−Ti Spinel: A Novel Magnetic Sorbent for Elemental Mercury Capture from Flue Gas

“…Furthermore, the concentration of Hg 2þ at the reactor exit was determined using the Ontario Hydro Method (OHM). 14 The breakthrough curve was generated by plotting the CVAAS voltage signal.…”

“…13 In China, the total mercury concentrations in the flue gas from coal-fired boilers are in the range of 1.92-27.2 μg m -3 , and elemental mercury accounts for 66-94% of the total mercury. 14 Many technologies have been investigated to control the emission of elemental mercury from flue gas, including sorbents, catalysts employed upstream of wet scrubbers, and photochemical oxidations. 10,12,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] Now, the mercury-sorbent material is extremely restricted in the application for at least three reasons: material recovery, removal of toxin from the industrial waste, 31 and cost of operation.…”

Characteristics of Mercury Emissions from a Coal-fired Power Plant

“…It is very close to Shuxiao Wang's resultin 2010, which tested a mercury mass concentration range from 17-385 µg/kg in six power plants [15]. After the burning of raw coal at the high temperature in combustion zone of boilers, the Hg in coal releases into the exhaust gas as elemental mercury (Hg 0 ) vapor.…”

Relative contributions of gaseous oxidized mercury and fine and coarse particle‐bound mercury to mercury wet deposition at nine monitoring sites in North America

“…In addition to Hg(II) gas-particle partitioning, FPBM is also formed from gas-particle transformation (conversion of GEM to GOM to PBM), such as occurs in coal combustion flue gas [Galbreath and Zygarlicke, 2000;Xiu et al, 2005;Lei et al, 2007;S. X. Wang et al, 2010].…”