Emissions Of Major Pollutants Research Articles

Effect of co-combustion of chicken litter and coal on emissions in a laboratory-scale fluidized bed combustor

Co-combustion of chicken litter (CL) with coal was performed in a laboratory-scale fluidized bed combustor to investigate the effect of CL combustion on pollutant emissions. The emissions of major gaseous pollutants including CO, SO2, H2S and NO and temperature distribution along the combustor were measured during the tests. Effects of CL fraction and secondary air on combustion characteristics were studied. The experimental results show that CL introduction increases CO emissions and reduces the levels of SO2. The ratio of H2S/SO2 increases with increasing fraction of CL. NO emissions either increase or decrease depending on the percentage of CL in the mixed fuels. The temperature in the freeboard region increases with increasing the fraction of CL while the reverse is true for the bed temperature.

Assessment of gaseous, PM and trace element emissions from a 300-MW lignite-fired boiler unit for various fuel qualities

Modeling of effects of fuel quality on the emissions of major pollutants (NO x , SO 2, CO 2 and PM) and eight trace elements (As, Co, Cr, La, Mo, Ni, Sb and U) from a 300-MW boiler unit fired with Thai lignite was the main focus of this study. The NO x and SO 2 emission models were validated with the use of experimental data. Emission rates and specific emissions (per MW h) of the major pollutants and trace elements were quantified by including efficiencies of the flue gas desulphurization system and electrostatic precipitators in the computations. As shown in this work, the contributions of 300-MW boiler units fired with Thai lignite to the “greenhouse” and “acid rain” gas emissions in the region are significant. Additionally, substantial amounts of hazardous As, Cr and Ni are emitted from the boiler units into the atmosphere via fly ash particles.

Co-combustion of municipal solid waste and Thai lignite in a fluidized bed

Co-combustion of high moisture municipal solid waste (MSW) and high sulfur Thai lignite in a laboratory scale bubbling fluidized bed has been investigated. This paper presents the effects of the mass fraction of a model MSW in the fuel mixture, as against 100% lignite, on the combustion characteristics that may be inferred from temperature distributions, carbon combustion efficiency and CO and CO 2 concentrations and on the emissions of major gaseous pollutants, including CO, SO 2, NO and N 2O. The influence of excess air and secondary air on those characteristics are also discussed. The results show that within the 40% MSW fraction tested, co-combustion is characterized by enhanced combustion of volatiles in the freeboard, a lower bed temperature and a combustion efficiency drop of up to 8%. Co-combustion either increases or reduces CO emission depending on the percentage of excess air. Reduction of up to 7–18% of SO 2 is observed at the 40% MSW fraction for the range of excess air and secondary air tested. Both NO and N 2O increase slightly with increasing fraction of MSW. Within the range of experimental conditions tested, the optimum condition for co-combustion in view of combustion efficiency and CO, NO and N 2O emissions is: 20% MSW, 40% excess air and 0.2 secondary to total ratio, although the reduction of SO 2 is slightly smaller than at other conditions.

Environmental inventories for future electricity supply systems for Switzerland

The Swiss Association of Producers and Distributors of Electricity (VSE) identified a number of possible supply mix options to meet the future electricity demand in Switzerland. In this context, PSI, in co–operation with ETHZ, analysed environmental inventories for the selected electricity supply systems. Life Cycle Analysis (LCA) was used to establish the inventories, covering the complete energy chains associated with fossil, nuclear and renewable systems. The assessment was performed on three levels: (1) individually for each system considered; (2) comparison of systems; (3) comparison of supply mix options. In absolute value, the emissions of the major pollutants considered are, in most cases, significantly reduced in comparison with the currently operating systems. Due to the considerable advancements in fossil power plant technologies, the relative importance of other activities increases in the fossil energy systems. Selected results for systems and supply options are given in the present paper.