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Coal-fired Power Plants (coal-fired + power_plant)
Selected AbstractsAtmospheric and hydrological transport modelling of SOx emissions in a unique verification contextAICHE JOURNAL, Issue 3 2010B. C. McLellan Abstract In this work, we developed a conceptual model incorporating atmospheric transport and hydrological removal of sulfur compounds from a single isolated source. A process engineering approach with conceptual tanks, reactors, pipes, and valves is used for environmental transport modeling. The work includes verification of the model using current data and historical soil sulfur data from a study 23 yrs earlier, collected from sites in a forest and within 20 km from an isolated coal-fired power plant. This verification opportunity is unique in that the power plant is the single major pollutant source within the airshed. In the conceptual process engineering model, environmental relationships with local soil conditions and climate are modeled. The model is validated for three sampling sites, and a sensitivity analysis shows that rainfall has the greatest variance among several other parameters, including sulfur emissions, dry deposition rate, runoff factor, permeability factor, and airshed dimensions. The model is shown to be suitable for a location-specific sustainability metrics application, but it has limitations that further research could improve on including the incorporation of more complexity with the modeling of ground and surface water flows, atmospheric and soil reactions, and vegetation effects. © 2009 American Institute of Chemical Engineers, AIChE J, 2010 [source] The synergetic effect of plasma and catalyst on simultaneous removal of SO2 and NOxASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2010Jun Han Abstract For the requirements of nitric oxide(NOx) and sulfur dioxide(SO2) removal in coal-fired power plant, a new nonthermal plasma system combined with catalyst was developed. Moreover, the effect of parameters such as temperature, atmosphere, residence time and additives (NH3 and methanol) on NOx (NO and NO2) and SO2 conversion rate was also experimentally evaluated. The results indicated that the new system could greatly promote the NOx conversion rate. As for SO2, the new system only had a slight influence. High temperature suppressed the NO oxidization and slightly promoted the SO2 oxidation. The long residence time was beneficial to the NOx and SO2 oxidization. In the absence of water, the additive of NH3 can improve NO, NOx and SO2 oxidization rate due to the reactions between NH3 and NOx or SO2. Contrary to NH3, methanol had a negative effect on NOx and SO2 oxidization. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Leaching characteristics of heavy metals in fly ash from a Chinese coal-fired power plantASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2010Xun Gong Abstract China is the largest coal ash producer in the world. Hydraulic ash transport systems are used in most coal-fired power plants, which lead to serious water pollution due to leaching of trace elements. The investigation on the leaching behavior of trace contaminants from coal ash is critical to environmental risk assessments. Batch leaching tests have been performed on the fly ash collected from each field of the electrostatic precipitator (ESP) of a coal-fired power plant to study the leaching characteristics of Cd, Cr, Pb and V. Leaching solutions included HCl solution of initial pH = 4 and NaOH solution of pH = 10. The liquid/solid (L/S) ratio was about 4:1 in all leaching tests. Fourteen leaching time intervals were selected, ranging from 15 min to 7 days. The results show that under studied experimental conditions, Cr has a relatively higher leachability in the acid-leaching solution, while Pb has a higher leachability in the alkaline solution. With the increase of leaching time, the leachability of Cr in each ash sample increases obviously. Within the same time interval, Cr in the ash sample from the last field of ESP has the highest leachability. The concentration of Cd in FA3 is the highest, but the leachability of Cd for FA3 is not the highest among the three ash samples. The concentration of V in FA1 is the highest; no increased trend with leaching time has been found in the experiment. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Magnetic Multi-Functional Nano Composites for Environmental ApplicationsADVANCED FUNCTIONAL MATERIALS, Issue 8 2009Jie Dong Abstract A novel concept is proposed to synthesize a new class of composites featuring magnetic, molecular sieve and metallic nanoparticle properties. These multi-functional materials have potential applications as recyclable catalysts, disinfectants and sorbents. The magnetic property enables effective separation of the spent composites from complex multiphase systems for regeneration and recycle, safe disposal of the waste and/or recovery of loaded valuable species. The zeolite molecular sieve provides a matrix which supports a remarkably new, simple, efficient and economical method to make stable, supported silver nanoparticles by silver ion exchange and controlled thermal reduction. The silver nanoparticles generated in this way have excellent properties such as high reactivity and good thermal stability without aggregation, which act as nano reactors for desired functionality in a wide range of applications. Magnetic component (Fe3O4), molecular sieve matrix (zeolite) and silver nanoparticles generated by ion exchange followed by controlled reduction, together form this unique novel composite with designed functions. It represents a practically operational, economical, sustainable and environmentally friendly new advanced functional material. This paper focuses on the novel synthesis and characterization of the composite, with an example of applications as sorbents for the removal of vapor-phase mercury from the flue gas of coal-fired power plants. [source] The perspectives of energy production from coal-fired power plants in an enlarged EUINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 9 2004P. Grammelis Abstract The aim of this paper is to present the current status of the coal-fired power sector in an enlarged EU (EU-15 plus EU member candidate states) in relation with the main topics of the European Strategy for the energy production and supply. It is estimated that 731 thermoelectric units, larger than 100 MWe, are operating nowadays, and their total installed capacity equals to 200.7 GWe. Coal contribution to the total electricity generation with reference to other fuel sources, is by far more intensive in the non-EU part (EU member candidate states), compared to the EU member states. It is expected that even after the enlargement, the European Union will strongly being related to coal. Enlargement will bring additional factors into play in order to meet the requirements of rising consumption, growing demand for conventional fuels and increasing dependence on imports. Besides the technology, boiler size, efficiency, age and environmental performance will determine the necessities of the coal-fired power sector in each country. Depending on the case, lifetime extension measures in operating coal-fired power plants or clean coal technologies can play an important role towards the energy sector restructuring. Low efficiency values in the non-EU coal-fired units and heavily aged power plants in EU countries will certainly affect decisions in favour of upgrading or reconstruction. The overall increase of efficiency, the reduction of harmful emissions from generating processes and the co-combustion of coal with biomass and wastes for generating purposes indicate that coal can be cleaner and more efficient. Additionally, plenty of rehabilitation projects based on CCT applications, have already been carried out or are under progress in the EU energy sector. The proclamations of the countries' energy policies in the coming decades, includes integrated renovation concepts of the coal-fired power sector. Further to the natural gas penetration in the electricity generation and CO2 sequestration and underground storage, the implementation of CCT projects will strongly contribute to the reduction of CO2 emissions in the European Union, according to the targets set in the Kyoto protocol. In consequence, clean coal technologies can open up new markets not only in the EU member candidate states, but also in other parts of the world. Copyright © 2004 John Wiley & Sons, Ltd. [source] Comprehensive process design study for layered-NOX -control in a tangentially coal fired boilerAICHE JOURNAL, Issue 3 2010Wei Zhou Abstract As emissions regulations for coal-fired power plants become stricter worldwide, layering combustion modification and post-combustion NOX control technologies can be an attractive option for efficient and cost-effective NOX control in comparison to selective catalytic reduction (SCR) technology. The layered control technology approach designed in this article consists of separate overfire air (SOFA), reburn, and selective noncatalytic reduction (SNCR). The combined system can achieve up to 75% NOX reduction. The work presented in this article successfully applied this technology to NRG Somerset Unit 6, a 120-MW tangential coal-fired utility boiler, to reduce NOX emissions to 0.11 lb/MMBtu (130 mg/Nm3), well under the US EPA SIP Call target of 0.15 lb/MMBtu. The article reviews an integrated design study for the layered system at Somerset and evaluates the performance of different layered-NOX -control scenarios including standalone SNCR (baseline), separated overfire air (SOFA) with SNCR, and gas reburn with SNCR. Isothermal physical flow modeling and computational fluid dynamics simulation (CFD) were applied to understand the boiler flow patterns, the combustible distributions and the impact of combustion modifications on boiler operation and SNCR performance. The modeling results were compared with field data for model validation and verification. The study demonstrates that a comprehensive process design using advanced engineering tools is beneficial to the success of a layered low NOX system. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Optimization of energy usage for fleet-wide power generating system under carbon mitigation optionsAICHE JOURNAL, Issue 12 2009A. Elkamel Abstract This article presents a fleet-wide model for energy planning that can be used to determine the optimal structure necessary to meet a given CO2 reduction target while maintaining or enhancing power to the grid. The model incorporates power generation as well as CO2 emissions from a fleet of generating stations (hydroelectric, fossil fuel, nuclear, and wind). The model is formulated as a mixed integer program and is used to optimize an existing fleet as well as recommend new additional generating stations, carbon capture and storage, and retrofit actions to meet a CO2 reduction target and electricity demand at a minimum overall cost. The model was applied to the energy supply system operated by Ontario power generation (OPG) for the province of Ontario, Canada. In 2002, OPG operated 79 electricity generating stations; 5 are fueled with coal (with a total of 23 boilers), 1 by natural gas (4 boilers), 3 nuclear, 69 hydroelectric and 1 wind turbine generating a total of 115.8 TWh. No CO2 capture process existed at any OPG power plant; about 36.7 million tonnes of CO2 was emitted in 2002, mainly from fossil fuel power plants. Four electricity demand scenarios were considered over a span of 10 years and for each case the size of new power generation capacity with and without capture was obtained. Six supplemental electricity generating technologies have been allowed for: subcritical pulverized coal-fired (PC), PC with carbon capture (PC+CCS), integrated gasification combined cycle (IGCC), IGCC with carbon capture (IGCC+CCS), natural gas combined cycle (NGCC), and NGCC with carbon capture (NGCC+CCS). The optimization results showed that fuel balancing alone can contribute to the reduction of CO2 emissions by only 3% and a slight, 1.6%, reduction in the cost of electricity compared to a calculated base case. It was found that a 20% CO2 reduction at current electricity demand could be achieved by implementing fuel balancing and switching 8 out of 23 coal-fired boilers to natural gas. However, as demand increases, more coal-fired boilers needed to be switched to natural gas as well as the building of new NGCC and NGCC+CCS for replacing the aging coal-fired power plants. To achieve a 40% CO2 reduction at 1.0% demand growth rate, four new plants (2 NGCC, 2 NGCC+CCS) as well as carbon capture processes needed to be built. If greater than 60% CO2 reductions are required, NGCC, NGCC+CCS, and IGCC+CCS power plants needed to be put online in addition to carbon capture processes on coal-fired power plants. The volatility of natural gas prices was found to have a significant impact on the optimal CO2 mitigation strategy and on the cost of electricity generation. Increasing the natural gas prices resulted in early aggressive CO2 mitigation strategies especially at higher growth rate demands. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Alternative stripper configurations for CO2 capture by aqueous aminesAICHE JOURNAL, Issue 12 2007Babatunde A. Oyenekan Abstract Aqueous absorption/stripping is a promising technology for the capture of CO2 from existing or new coal-fired power plants. Four new stripper configurations (matrix, internal exchange, flashing feed, and multipressure with split feed) have been evaluated with seven model solvents that approximate the thermodynamic and rate properties of 7m (30 wt %) monoethanolamine (MEA), potassium carbonate promoted by piperazine (PZ), promoted MEA, methyldiethanolamine (MDEA) promoted by PZ, and hindered amines. The results show that solvents with high heats of absorption (MEA, MEA/PZ) favor operation at normal pressure. The relative performance of the alternative configurations is matrix > internal exchange > multipressure with split feed > flashing feed. MEA/PZ and MDEA/PZ are attractive alternatives to 7m MEA. The best solvent and process configuration, matrix with MDEA/PZ, offers 22 and 15% energy savings over the baseline and improved baseline, respectively, with stripping and compression to 10 MPa. The energy requirement for stripping and compression to 10 MPa is about 20% of the power output from a 500 MW power plant with 90% CO2 removal. © 2007 American Institute of Chemical Engineers AIChE J, 2007 [source] Mental retardation and prenatal methylmercury toxicityAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 3 2006Leonardo Trasande MD Abstract Background Methylmercury (MeHg) is a developmental neurotoxicant; exposure results principally from consumption of seafood contaminated by mercury (Hg). In this analysis, the burden of mental retardation (MR) associated with methylmercury exposure in the 2000 U.S. birth cohort is estimated, and the portion of this burden attributable to mercury (Hg) emissions from coal-fired power plants is identified. Methods The aggregate loss in cognition associated with MeHg exposure in the 2000 U.S. birth cohort was estimated using two previously published dose-response models that relate increases in cord blood Hg concentrations with decrements in IQ. MeHg exposure was assumed not to be correlated with native cognitive ability. Previously published estimates were used to estimate economic costs of MR caused by MeHg. Results Downward shifts in IQ resulting from prenatal exposure to MeHg of anthropogenic origin are associated with 1,566 excess cases of MR annually (range: 376,14,293). This represents 3.2% of MR cases in the US (range: 0.8%,29.2%). The MR costs associated with decreases in IQ in these children amount to $2.0 billion/year (range: $0.5,17.9 billion). Hg from American power plants accounts for 231 of the excess MR cases/year (range: 28,2,109), or 0.5% (range: 0.06%,4.3%) of all MR. These cases cost $289 million (range: $35 million,2.6 billion). Conclusions Toxic injury to the fetal brain caused by Hg emitted from coal-fired power plants exacts a significant human and economic toll on American children. Am. J. Ind. Med. 49:153,158, 2006. © 2006 Wiley-Liss, Inc. [source] Mercury and halides emissions from 200 MW pulverized coal combustion boilerASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2010Hui Wu Abstract Mercury emission from coal-fired power plants is the major industrial source of mercury pollution in China. For a better understanding about the coal combustion Hg emission in China, a field measurement was conducted on a 200 MW pulverized coal fired boiler. Halides being proved to be mercury transformation participators, the U.S. EPA (Environmental Protection Agency) recommended Ontario Hydro method (OHM) and EPA Method 26A were adopted to determine the speciation of Hg and halides in postcombustion flue gases, respectively. Results indicated that, as the flue gas cooling down, the percentage of oxidized mercury in total gas phase mercury (Hg2+(g)/HgT(G)) increased from 41% to about 74% across the electrostatic precipitator (ESP) outlet. Oxidized mercury (Hg2+(g)) was more apt to be absorbed onto the fly ash. The main halides measured in flue gas were HF and HCl, while the concentrations of Cl2 and HBr were extremely low and no Br2 was detected in flue gas. Analysis indicated that acid flue gas components, such as HCl, HF, SO2 and NO, showed a certain extent of promotion on Hg oxidation. The measured mercury emission factor (EMF) in this test was 5.63 g/1012J (13.1 lb/1012Btu). Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Hazardous air pollutants emission from coal and oil-fired power plantsASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2010Deepak Pudasainee Abstract Hazardous air pollutants (HAPs) emission characteristics from coal (anthracite, bituminous) and oil-fired power plants were studied in order to control pollutants by formulating US maximum achievable control technology (MACT)-like regulation in Korea. Sampling and analysis were carried out according to either Korean standard test method or US EPA method. Relatively lower levels of NOx and SOx were emitted from plants burning bituminous than the anthracite coal. Less dust was emitted from oil-fired power plants. Mercury, lead, and chromium were dominant in coal-fired power plants, following which, nickel and chromium were emitted from oil-fired power plants. The major volatile organic compounds (VOCs) emitted from coal-fired plants were 1,2-dichloroethane, benzene, carbon tetrachloride, chloroform, trichloro-ethylene. The emission of mercury and other heavy metals in flue gas was attributed to fuel types, operating conditions, residence time in the control devices and air pollution control devices configuration. After emission tests in the field and on analysis of the continuous emission monitoring data collected from facilities under operation and consideration of other various factors, management guidelines will be suggested with special reference to US MACT-like regulation. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Leaching characteristics of heavy metals in fly ash from a Chinese coal-fired power plantASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2010Xun Gong Abstract China is the largest coal ash producer in the world. Hydraulic ash transport systems are used in most coal-fired power plants, which lead to serious water pollution due to leaching of trace elements. The investigation on the leaching behavior of trace contaminants from coal ash is critical to environmental risk assessments. Batch leaching tests have been performed on the fly ash collected from each field of the electrostatic precipitator (ESP) of a coal-fired power plant to study the leaching characteristics of Cd, Cr, Pb and V. Leaching solutions included HCl solution of initial pH = 4 and NaOH solution of pH = 10. The liquid/solid (L/S) ratio was about 4:1 in all leaching tests. Fourteen leaching time intervals were selected, ranging from 15 min to 7 days. The results show that under studied experimental conditions, Cr has a relatively higher leachability in the acid-leaching solution, while Pb has a higher leachability in the alkaline solution. With the increase of leaching time, the leachability of Cr in each ash sample increases obviously. Within the same time interval, Cr in the ash sample from the last field of ESP has the highest leachability. The concentration of Cd in FA3 is the highest, but the leachability of Cd for FA3 is not the highest among the three ash samples. The concentration of V in FA1 is the highest; no increased trend with leaching time has been found in the experiment. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] | ||||||||||