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Air quality III: mercury, trace elements, and particulate matter
Fuel Processing Technology 85 (2004) 423 – 424 www.elsevier.com/locate/fuproc
Preface
Air quality III: mercury, trace elements, and particulate matter The papers in this special issue were presented as part of the Air Quality III Conference on Mercury, Trace Elements, and Particulate Matter that was held September 9– 12, 2002, in Arlington, VA. The conference brought together 400 leaders from research, industry, and government to address air quality issues concerning health and ecosystems, emission prevention and control, measurement methods, and atmospheric reactions and modeling.
1. Mercury Mercury is a high-priority regulatory concern because of its persistence and bioaccumulation in the environment and evidence of serious adverse effects on the neurological development of children. After eliminating mercury from most products and controlling emissions from incinerators, coal-fired utilities are now the largest single source of mercury in the United States, estimated to account for one-third of anthropogenic emissions. Mercury control at coal-fired power plants faces significant challenges. The continuing challenges for the development of effective mercury control technologies include measuring the forms of mercury on a continuous basis, understanding the factors that influence mercury speciation during combustion and gas cooling, impact on mercury speciation on mercury control technologies, and applying the most cost-effective technology for a given power plant and fuel source. This special issue provides information on recent research on the following:
Measurement of total mercury and mercury forms in flue gas using wet chemistry methods, including Ontario Hydro Method, US Environmental Protection Agency (EPA) Method 29, and EPA Method 101A, and continuous instrumental measurements on coal flue gases are difficult because of the low mercury concentrations. Dependence of the forms of mercury in flue gas on coal composition and system conditions. Application of sorbent injection for coal-fired power plants that have an existing particulate control device but no wet flue gas desulfurization (FGD) system. Ability of lime and limestone wet scrubbers to capture oxidized mercury in the entering flue gas but essentially none of the elemental mercury. Addition of chemicals to increase oxidation to enhance mercury capture in scrubbers and to prevent reemission from scrubber solution.
0378-3820/$ - see front matter. Published by Elsevier B.V. doi:10.1016/j.fuproc.2004.02.001
424
Preface
Results of field tests performed at power plants to investigate the effects of selective catalytic reduction (SCR) used for controlling NOx emissions on mercury speciation and capture. Changes in the level of mercury oxidation across SCR reactors at different plants were coal specific. Stability of captured mercury in scrubber sludge, fly ash, and other coal combustion byproducts (CCBs).
2. Particulate matter Fine particles in the air have been of considerable environmental interest in recent years because of a number of research studies correlating short-term exposure of ambient levels of fine particulate matter (PM) with acute respiratory and cardiovascular distress. PM may be emitted directly (primary PM) or formed in the atmosphere (secondary PM). The types of PM include organic [soot and polycyclic aromatic hydrocarbon (PAHs)] or inorganic (metals, sulfates, nitrates, and other inorganic species), or combinations of both organic and inorganic constituents. The special issue provides key information on the following:
Application of a comprehensive air quality model to characterize atmospheric processes to study ozone, PM, and acid deposition. Results of modeling of fine particulate and trace metals to determine the local environmental impact of coal-fired power plants. The complex chemical and physical transformations during combustion to produce primary particles and secondary particle precursors. Changes in the abundance of fine ash when firing different fuels and blends. This phenomenon was attributed to the increased availability of sites for nucleation and condensation of vapor-phase species because of the increase in ash content of the fuel. Changes in characteristics of primary PM2.5 from coal combustion sources firing a range of coal types.
Advances in understanding the chemical and physical transformations that govern the capture or emission of mercury as well as primary particulate and precursors for secondary particulate will continue to drive the development of control technologies that define the limits of achievable regulation. I wish to express my sincere appreciation to the authors for their effort in preparing the papers; to the extensive group of reviewers who provided critical review of the papers that increased the overall quality of this special issue; and to Ms. Constance Wixo for her persistent encouragement of authors, reviewers, and the editor to complete their tasks. Steven A. Benson Energy & Environmental Research Center, University of North Dakota, P.O. Box 9018, Grand Forks, ND 58202-9018, USA E-mail address: [email protected] Tel.: +1-701-777-5177; fax: +1-701-777-5181
Preface
Air quality III: mercury, trace elements, and particulate matter The papers in this special issue were presented as part of the Air Quality III Conference on Mercury, Trace Elements, and Particulate Matter that was held September 9– 12, 2002, in Arlington, VA. The conference brought together 400 leaders from research, industry, and government to address air quality issues concerning health and ecosystems, emission prevention and control, measurement methods, and atmospheric reactions and modeling.
1. Mercury Mercury is a high-priority regulatory concern because of its persistence and bioaccumulation in the environment and evidence of serious adverse effects on the neurological development of children. After eliminating mercury from most products and controlling emissions from incinerators, coal-fired utilities are now the largest single source of mercury in the United States, estimated to account for one-third of anthropogenic emissions. Mercury control at coal-fired power plants faces significant challenges. The continuing challenges for the development of effective mercury control technologies include measuring the forms of mercury on a continuous basis, understanding the factors that influence mercury speciation during combustion and gas cooling, impact on mercury speciation on mercury control technologies, and applying the most cost-effective technology for a given power plant and fuel source. This special issue provides information on recent research on the following:
Measurement of total mercury and mercury forms in flue gas using wet chemistry methods, including Ontario Hydro Method, US Environmental Protection Agency (EPA) Method 29, and EPA Method 101A, and continuous instrumental measurements on coal flue gases are difficult because of the low mercury concentrations. Dependence of the forms of mercury in flue gas on coal composition and system conditions. Application of sorbent injection for coal-fired power plants that have an existing particulate control device but no wet flue gas desulfurization (FGD) system. Ability of lime and limestone wet scrubbers to capture oxidized mercury in the entering flue gas but essentially none of the elemental mercury. Addition of chemicals to increase oxidation to enhance mercury capture in scrubbers and to prevent reemission from scrubber solution.
0378-3820/$ - see front matter. Published by Elsevier B.V. doi:10.1016/j.fuproc.2004.02.001
424
Preface
Results of field tests performed at power plants to investigate the effects of selective catalytic reduction (SCR) used for controlling NOx emissions on mercury speciation and capture. Changes in the level of mercury oxidation across SCR reactors at different plants were coal specific. Stability of captured mercury in scrubber sludge, fly ash, and other coal combustion byproducts (CCBs).
2. Particulate matter Fine particles in the air have been of considerable environmental interest in recent years because of a number of research studies correlating short-term exposure of ambient levels of fine particulate matter (PM) with acute respiratory and cardiovascular distress. PM may be emitted directly (primary PM) or formed in the atmosphere (secondary PM). The types of PM include organic [soot and polycyclic aromatic hydrocarbon (PAHs)] or inorganic (metals, sulfates, nitrates, and other inorganic species), or combinations of both organic and inorganic constituents. The special issue provides key information on the following:
Application of a comprehensive air quality model to characterize atmospheric processes to study ozone, PM, and acid deposition. Results of modeling of fine particulate and trace metals to determine the local environmental impact of coal-fired power plants. The complex chemical and physical transformations during combustion to produce primary particles and secondary particle precursors. Changes in the abundance of fine ash when firing different fuels and blends. This phenomenon was attributed to the increased availability of sites for nucleation and condensation of vapor-phase species because of the increase in ash content of the fuel. Changes in characteristics of primary PM2.5 from coal combustion sources firing a range of coal types.
Advances in understanding the chemical and physical transformations that govern the capture or emission of mercury as well as primary particulate and precursors for secondary particulate will continue to drive the development of control technologies that define the limits of achievable regulation. I wish to express my sincere appreciation to the authors for their effort in preparing the papers; to the extensive group of reviewers who provided critical review of the papers that increased the overall quality of this special issue; and to Ms. Constance Wixo for her persistent encouragement of authors, reviewers, and the editor to complete their tasks. Steven A. Benson Energy & Environmental Research Center, University of North Dakota, P.O. Box 9018, Grand Forks, ND 58202-9018, USA E-mail address: [email protected] Tel.: +1-701-777-5177; fax: +1-701-777-5181