Mercury and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and Utilizaton

David Hassett ; Loreal Heebink ; Debra Pflughoeft-Hassett ; Tera Buckley ; Erick Zacher ; Mei Xin ; Mae Sexauer Gustin ; Rob Jung

关键词: ACTIVATED CARBON;    AMBIENT TEMPERATURE;    ARSENIC;    BY-PRODUCTS;    CADMIUM;    CARBON;    CHROMIUM;    COAL;    COMBUSTION;    DESULFURIZATION;    FLUE GAS;    FLY ASH;    MERCURY;    NICKEL;    POWER PLANTS;    SELENIUM;    WATER;   

DOI  :  10.2172/981821
RP-ID  :  None
PID  :  OSTI ID: 981821
Others  :  TRN: US201013%%264

美国|英语

来源: SciTech Connect

【 摘 要 】

The University of North Dakota Energy & Environmental Research Center (EERC) conducted a multiyear study to evaluate the impact of mercury and other air toxic elements (ATEs) on the management of coal combustion by-products (CCBs). The ATEs evaluated in this project were arsenic, cadmium, chromium, lead, nickel, and selenium. The study included laboratory tasks to develop measurement techniques for mercury and ATE releases, sample characterization, and release experiments. A field task was also performed to measure mercury releases at a field site. Samples of fly ash and flue gas desulfurization (FGD) materials were collected preferentially from full-scale coal-fired power plants operating both without and with mercury control technologies in place. In some cases, samples from pilot- and bench-scale emission control tests were included in the laboratory studies. Several sets of 'paired' baseline and test fly ash and FGD materials collected during full-scale mercury emission control tests were also included in laboratory evaluations. Samples from mercury emission control tests all contained activated carbon (AC) and some also incorporated a sorbent-enhancing agent (EA). Laboratory release experiments focused on measuring releases of mercury under conditions designed to simulate CCB exposure to water, ambient-temperature air, elevated temperatures, and microbes in both wet and dry conditions. Results of laboratory evaluations indicated that: (1) Mercury and sometimes selenium are collected with AC used for mercury emission control and, therefore, present at higher concentrations than samples collected without mercury emission controls present. (2) Mercury is stable on CCBs collected from systems both without and with mercury emission controls present under most conditions tested, with the exception of vapor-phase releases of mercury exposed to elevated temperatures. (3) The presence of carbon either from added AC or from unburned coal can result in mercury being sorbed onto the CCB when exposed to ambient-temperature air. The environmental performance of the mercury captured on AC used as a sorbent for mercury emission control technologies indicated that current CCB management options will continue to be sufficiently protective of the environment, with the potential exception of exposure to elevated temperatures. The environmental performance of the other ATEs investigated indicated that current management options will be appropriate to the CCBs produced using AC in mercury emission controls.