Combustion source emissions compared

The use of plastics as an energy source was demonstrated on a commercial scale at ICl Materials plastics manufacturing site in Dumfries, UK. This paper covers the preparation and use of pre- and post-consumer plastics as supplementary fuels in a circulating fluidised bed boiler specially designed for co-combustion with coal. Full emissions data on the 15% mixtures of individual plastics with coal are given, together with calculations of thermal efficiencies. Measurements by an independent body (British Coal Research Establishment) confirmed that the co-combustion of coal and plastic reduces some emissions compared with coal alone. Thermal efficiencies of around 80% were achieved and this heat was used effectively during the production of plastics. 7 refs. 

The Consolidated Edison test results, as shown in Table VI, indicated complete suitability of SRC-II coal liquids as a high quality boiler fuel. No operational problems were encountered and no deposits were observed. Combustion efficiency was comparable to that for the low-sulfur No. 6 fuel oil, as were the levels of carbon monoxide and hydrocarbon emissions. Modifications to burner equipment required to handle the SRC-II fuel oil are considered to be no more extensive than those required for similar variations in petroleum fuels. Particulate emissions for the SRC-II fuel oil were generally lower than for the No. 6 fuel oil, and were in all cases below the new source performance standards proposed by EPA (0.03 lbs/MM Btu). 

The ultrafine range is usually composed of emissions from local combustion sources or particles generated by atmospheric photochemical activity that leads to homogeneous nucleation. The principal mechanism of decay of the ultrafine range is attachment to particles in the accumulation mode by diffusion. Neglecting the Brownian motion of the coarse particles compared with the fine particles, the fractional rate of decay of particles in the ultrafine range is given by (Chapter 7)... 

A comparative evaluation of various combustion sources indicates that motor-vehicle emissions make a major contribution to the mutagenicity observed in ambient air. 

The acidity of rainfall is associated with carbon, sulphur and nitrogen oxidation, principally from industrial and fossil fuel combustion sources. These anthropogenic emissions may induce a disequilibrium in the atmosphere redox balance, a system more susceptible to these modifications because of its lower dimensions when compared to the hydrosphere and lithosphere (Stum et al., 1987). 

Test a hypothesis about the source of the problem, such as checking emissions from a piece of equipment. Testing for "indicator" compounds associated with particular types of building conditions Peak carbon dioxide CO2) concentrations over 1000 ppm (parts per million) are an indicator of underventilation. Carbon monoxide (CO) over several ppm indicates inappropriate presence of combustion by-products (which may also account for high CO2 readings). Compare any measured concentrations to guidelines or standards. 

Plasmas compare favourably with both the chemical combustion flame and the electrothermal atomiser with respect to the efficiency of the excitation of elements. The higher temperatures obtained in the plasma result in increased sensitivity, and a large number of elements can be efficiently determined. Common plasma sources are essentially He MIP, Ar MIP and Ar ICP. Helium has a much higher ionisation potential than argon (24.5 eV vs. 15.8 eV), and thus is a more efficient ionisation source for many nonmetals, thereby resulting in improved sensitivity. Both ICPs and He MIPs are utilised as emission detectors for GC. Plasma-source mass spectrometry offers selective detection with excellent sensitivity. When coupled to chromatographic techniques such as GC, SFC or HPLC, it provides a method for elemental speciation. Plasma-source detection in GC is dominated by GC-MIP-AES... 

The use of EF values allows us to set limits on possible sources of elements. In Figure 1, EF values for six cities are compared with the ranges for particles from nine coal-fired power plants. For llthophlle elements such as SI, Tl, Th, K, Mg, Fe and many others not shown, E values are close to unity as expected, as these elements have mainly crustal sources, l.e., entrained soil and the aluminosilicate portion of emissions from coal combustion (see Table I). Many other elements are strongly enriched In some or all cities, and, to account for them, we must find sources whose particles have large values for those elements. Some are fairly obvious from the above discussions Pb from motor vehicles, Na from sea salt In coastal cities, and V and, possibly, N1 from oil In cities where residual oil Is used In large amounts (Boston, Portland, Washington). 

Dichloromethane is a widely used industrial and academic laboratory solvent. New natural sources are recognized subsequent to the previous review, although the amounts are small compared to industrial emissions (Table 3.2). These include estimates of biomass combustion (256, 283, 286), oceanic sources (250, 253, 256, 275, 302), wetlands (275), and volcanoes (216, 217). Macroalgae (Desmarestia... 

There was comparatively little information on the release of PCBs as unintentionally produced POPs. PCBs are known to be produced as unintentional combustion by-products of incineration and combustion processes. The current UNEP Toolkit (2003) does not give EFs for PCBs. There was little information on the release of PCBs from known local emission sources. A few measured emission data were available from a number of incinerators, crematoria and power plants to permit local EFs to be derived and the annual release of dioxin-like PCBs to be estimated for these processes. Results indicated that the measured total annual air emission of dioxin-like PCBs was very low (less than 0.1 g TEQ). Compilation of the local dioxin-like PCB emission profile would await further emission data from other potential sources. 

Polychlorinated Biphenyls (PCBs). The PCBs were observed in the stack effluents during the combustion of coal but these compounds were not produced in the combustion process by a de novo synthesis or from precursor compounds. The source of the PCBs was the indoor air used to support the combustion. This indoor air contained 0.11 ug/M3 of PCBs the concentration of PCBs in the stack gas was only 0.02 yg/M3 when coal containing no detectable level of PCBs was burned. For perspective, this emission level should be compared to the average ambient outdoor air level of about 0.006 yg/M3. 

The Maximum Achievable Control Technology (MACT) emission limitations required by the 1990 Clean Air Act Amendments (CAAA) show the ultimate effect of the ratcheting process. After a little more than two decades of ratcheting, MWCs have become a comparatively minor source of combustion-related air pollution. Other artificial and natural sources such as automobiles, trucks, power plants, fireplaces, wood stoves, metal production furnaces, industrial manufacturing processes, volcanoes, forest fires, and backyard trash burning are now the major known sources of combustion-related pollutants. 

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