Source Profiles of Particulate Matter Emissions from a Pilot-Scale Boiler Burning North American Coal Blends

Abstract

Recent awareness of suspected adverse health effects from ambient particulate matter (PM) emission has prompted publication of new standards for fine PM with aerodynamic diameter less than 2.5 µm (PM 2.5 ). However, scientific data on fine PM emissions from various point sources and their characteristics are very limited. Source apportionment methods are applied to identify contributions of individual regional sources to tropospheric particulate concentrations. The existing industrial database developed using traditional source measurement techniques provides total emission rates only, with no details on chemical nature or size characteristics of particulates. This database is inadequate, in current form, to address source-receptor relationships.A source dilution system was developed for sampling and characterization of total PM, PM 2.5 , and PM 10 (i.e., PM with aerodynamic diameter less than 10 µm) from residual oil and coal combustion. This new system has automatic control capabilities for key parameters, such as relative humidity (RH), temperature, and sample dilution. During optimization of the prototype equipment, three North American coal blends were burned using a 0.7-megawatt thermal (MW t ) pulverized coal-fired, pilot-scale boiler. Characteristic emission profiles, including PM 2.5 and total PM soluble acids, and elemental and carbon concentrations for three coal blends are presented.Preliminary results indicate that volatile trace elements such as Pb, Zn, Ti, and Se are preferentially enriched in PM 2.5 . PM 2.5 is also more concentrated in soluble sulfates relative to total PM. Coal fly ash collected at the outlet of the electrostatic precipitator (ESP) contains about 85-90% PM 10 and 30-50% PM 2.5 . Particles contain the highest elemental concentrations of Si and Al while Ca, Fe, Na, Ba, and K also exist as major elements. Approximately 4-12% of the materials exists as soluble sulfates in fly ash generated by coal blends containing 0.2-0.8% sulfur by mass. Source profile data for an eastern U.S. coal show good agreement with those reported from a similar study done in the United States. Based on the inadequacies identified in the initial sampling equipment, a new, plume-simulating fine PM measurement system with modular components for field use is being developed for determining coal combustion PM source profiles from utility boiler stacks. INTRODUCTIONA considerable increase in scientific and regulatory discussions and research activities has been noted since new fine particulate standards were published in North America.

The Steubenville Comprehensive Air Monitoring Program (SCAMP): Concentrations and Solubilities of PM2.5 Trace Elements and Their Implications for Source Apportionment and Health Research

“…This apparent physical incongruity may be the result of a sampling bias, because samples for water-soluble and acid-digestible analyses were collected using separate samplers. It could also be attributable to an analytical error (e.g., 75 As and 80 Se are prone to interferences by species such as 40 Ar 35 Cl ϩ and 40 Ar 2 ϩ , respectively) 32 or digestion error (e.g., volatile losses of AsCl 3 and SeOCl 2 can occur after digestion in hot HCl). 51 These potential errors are guarded against by use of the DRC and a capped digestion procedure with a post-digestion cooling period, however, and are not supported by the performance data presented in Table 1.…”

“…All of these elements, as well as Al, As, Ca, K, Fe, Mn, V, and Zn, which also appear in the source 7 profile (Figure 5g), are expected in PM emissions from coal-fired plants. 72,75 The largest contributor to the mass associated with source 7 was SO 4 2Ϫ , likely reflecting some primary sulfate emissions, as well as some secondary SO 4 2Ϫ formed by the atmospheric conversion of SO 2 during transport from the stack to the receptor site. As expected for coal-fired power plant emissions, 68,75 carbon species (i.e., EC ϩ OM) accounted for very little (ϳ8%) of the mass associated with source 7.…”

“…ICP-MS has been used by several recent PM 2.5 studies, 27,28 because it exhibits better sensitivity than conventional energy dispersive XRF for determining certain elements that are present in part-perbillion to part-per-trillion amounts. However, the capabilities of conventional low-resolution ICP-MS are limited by polyatomic and isobaric interferences that impede the determination of isotopes such as 39 K, 40 Ca, 51 V, 52 Cr, 56 Fe, 75 As, and 80 Se. SCAMP is among the first PM 2.5 studies to use ICP-MS equipped with a DRC to minimize these interferences.…”

Measurements of OC and EC in Coarse Particulate Matter in the Southeastern United States

“…When a particle was detected, size measurements were made by tracing the dimensions of the particle with the electron beam followed by the acquisition of an EDS and a digital image. The maximum and minimum particle diameters acquired during particle size measurement were used to estimate the volume of each particle assuming an oblate ellipsoid, according to the following equation 22,23 :…”

Development of Fine Particulate Emission Factors and Speciation Profiles for Oil and Gas-Fired Combustion Systems

“…Researchers at DRI applied this sampler to coal-fired boil-ers, a refinery fluid catalytic cracking unit and to various smaller area sources such as fireplaces and cooking stoves (Chow et al, 2004;. Lee et al (2000) and Lee (2001) (Dayton and Bursey, 2001) and Diesel engine exhaust (Miller et al, 1998). O'Connor (2003) and O'Connor andGenest (2003a, 2003b) applied a similar sampler (Figure 2-8) to pulp and paper industry sources, including sampling in saturated flue gases from several sources equipped with wet flue gas desulfurization scrubbers.…”