Coal-fired power plants particulate emissions

A more effective approach to clean air policy, and one example of a sensible program being implemented by the federal government, is the Clean Air Interstate Rule or CAIR, intended to reduce emissions of particulate matter and NO in the eastern United States. EPA finalized the CAIR rules on March 10, 2005 in response to a finding of non-attainment of National Ambient Air Quality Standards (NAAQS) for fine particulate matter and ozone formation. CAIR requires reductions in SOj and NOj emissions from coal-fired power plants the emissions limits spelled out in the CAIR plan affect electric utilities in 28 eastern states and the District of Columbia. Emissions reductions are to be achieved through a market-based cap-and-trade system similar to other air pollution programs EPA has put into practice over the last few decades. 

Particulate emissions data for 21 studies of coal-fired power plants were compiled for use in receptor models. Enrichment factors were calculated (relative to Al) with respect to the earth s crust (EFcrust) and to the input coal (EFcoai). Enrichment factors for input coals relative to crustal material were also calculated. Enrichment factors for some elements that are most useful as tracers of coal emissions (e.g., As, Se) vary by more than ten-fold. The variability can be reduced by considering only the types of plants used in a given area, e.g., plants with electrostatic precipitators (ESPs) burning bituminous coal. For many elements (e.g., S, Se, As, V), EFcrust values are higher for plants with scrubbers than for plants with ESPs. For most lithophiles, EFcrust values are similar for the coarse (>2.5 ym) and fine (<2.5 ym) particle fractions. 

Using both a hybrid receptor model, developed by Lewis and Stevens ( 2) and modified by Gordon and Olmez (3), and a simple model of emission from the Ohio River Valley, we compare the results of the College Park (CP) samples as well as those of another continuous set of samples taken from July 3-29, 1983 at Wallops Island, VA (WI), to predicted results. Single-source differential equations (2) are used to describe the time-varying concentrations of SO2, SO and a particulate element characteristic of coal-fired power plant emissions (chosen here as Se). An additional equation (3) can be added to describe the concentration variation of B(0H)3 The following rate constants apply to the concentrations of the four species in question ... 

Source Apportionment Assume that for a rural site the measured PM 0 concentration is 32jig m-3 containing 2.58 pgm-3 Si and 3.84pgm 3Fe. The two major sources contributing to the location s particulate concentration are a coal-fired power plant and soil-related dust. Analysis of the emissions of these sources indicates that the soil contains 200 mg(Si) g (20% of the total emissions) and 32 mg(Fe) g 1 (3.2% of the total emissions), while the particles emitted by the power plant contain IOmg(Si)g (1%) and 150mg(Fe)g (15%). Neglecting Si and Ft contributions from other sources... 

The characteristics of several QCM instruments for aerosol measurement have been reviewed (ll). Particles are collected by impaction, electrostatic precipitation or both. The mass sensitivity is reported to be affected by the location of deposited particles on the crystal, the size of the particles, and the type of coating. In addition, the sensitivity changes as the crystal becomes loaded. Despite some limitations, most of the studies Indicated that QCMs can be successfully used for aerosol measurement with good correlation coefficient with the reference filtration method. Applications included measurement of aerosol in ambient air, particulate emission from automobiles and diesel engines, smoke plume from a coal-fired power plant, solid fueled rocket plvune, and particulate matter in the effluents in combustion sources. 

A major industrial source of particulate matter in the environment is coal-fired combustion for electricity generation. Source performance standards in the US restrict total particulate emissions from new coal-fired power plants to 6.4 ng... 

Sulfur and nitrogen oxides are not the only output from coal combustion that may leave a detectible environmental impact. Particulate matter (fly ash) is also released during coal combustion and can be detected near coal-fired power plants (Flanders, 1999 Godbeer and Swain, 1995 Kapicka et al, 1999). The focus of the present study was to test whether these particulate emissions have produced a detectible impact on the geochemical landscape downwind from power plants. It is already known that atmospheric inputs can be detected in lake and reservoir sediments (Locke and Bertine, 1986 Norton, 1986), and we sought to further test whether atmospheric coal fly ash inputs could be identified and quantified. 

Emissions from coal-fired power plants have decreased substantially in the last decades due to improved understanding of pollutant formation mechanisms and combustion science. NOx is routinely reduced by 50-70% in major power stations, well over 99% of the particulate matter is... 

This chapter reviews existing and emerging applications for membrane technology in stationary power generation. For example, filters are used to clean intake air for combustion and remove particulate emissions from coal-fired power plants [1], while monbrane technologies are used for the purification of NG [2] and the conditioning of boiler feedwater for use in steam turbines [3]. The discussion is divided into three sections ... 

The sulfur gas produced by burning coal can be partially removed with scrubbers or filters. In conventional coal plants, the most common form of sulfur dioxide control is through the use of scrubbers. To remove the SO2, the exhaust from a coal-fired power plant is passed through a mixture of lime or limestone and water, which absorbs the SO2 before the exhaust gas is released through the smokestack. Scrubbers can reduce sulfur emissions by up to 90%, but smaller particulates are less likely to be absorbed by the limestone and can pass out the smokestack into the atmosphere. In addition, scrubbers require more energy to operate, thus increasing the amount of coal that must be burned to power their operation. 

Bhanarkar, A.D., Gavane, A.G., Tajne, D.S., Tamhane, S.M., and Nema, P. 2008. Composition and size distribution of particulates emissions from a coal-fired power plant in India. Fuel, 87 2095-2101. 

Emissions of SO, (NO and NO2), hydrocarbons (HCs), CO, and particulate matter from stationary and mobile combustion systems are serious hazards to human and animal health, and cause add rain and smog, which leads to damage of property, agriculture, and forests. Mobile sources account for a large fraction of these emissions, especially of NO, and CO. Stationary sources like coal-fired power plants are also major contributors, and account in most countries for most of the SO2 and about half of the NO, emissions (Table 5.4.1). 

Air emissions testing data from five facilities were evaluated for this report. The results are summarized here, by pollutant. The most extensive testing was performed by WP L, who tested criteria pollutants, heavy metals, dioxins and furans, and other organic compounds. Table 6-2 summarizes test data for all criteria pollutants at WP L.18 Ohio Edison tested particulate, S02, NOx, and lead emissions results from this whole tire test are provided in Table 6-3.12 Illinois Power tested PM, metals, and S02 their emissions data are summarized in Table 6-4.4 In 1979, United Power Association performed two TDF tests at their Minnesota facility, and conducted air emissions tests during the first test burn for particulate, NOx, SOz, sulfuric acid, and chloride.17 These emission results are summarized in Table 6-5.17 Northern States Power tested TDF in their wood-fired utility boiler in 1982, without much success.9 Their emissions data are summarized in Table 6-6.9 Comparisons of the data from these plants are provided in the pollutant specific discussions that follow the Northern States Power data are not included with graphical summaries of the other four facilities, because its boiler is wood fired, while the other four co-fire the TDF with coal. 

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