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Utility Boiler (utility + boiler)
Selected AbstractsMeasurements and numerical simulations for optimization of the combustion process in a utility boilerINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2004A. Vikhansky Abstract A three-dimensional computational fluid dynamics code was used to analyse the performance of 550MW pulverized coal combustion opposite a wall-fired boiler (of IEC) at different operation modes. The main objective of this study was to prove that connecting plant measurements with three-dimensional furnace modelling is a cost-effective method for design, optimization and problem solving in power plant operation. Heat flux results from calculations were compared with measurements in the boiler and showed good agreement. Consequently, the code was used to study hydrodynamic aspects of air,flue gases mixing in the upper part of the boiler. It was demonstrated that effective mixing between flue gases and overfire air is of essential importance for CO reburning. From our complementary experimental-numerical effort, IEC considers a possibility to improve the boiler performance by replacing the existing OFA nozzles by those with higher penetration depth of the air jets, with the aim to ensure proper mixing to achieve better CO reburning. 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] NOx emissions of an opposed wall-fired pulverized coal utility boilerASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2010Xiaotao Gao Abstract The present paper was addressed to the effects of operational variables and coal properties on NOx emission level of a 600-MW opposed wall-fired pulverized coal utility boiler. The in situ experiments were performed to study the effects of operational variables on boiler performance by changing individual variables while the other variables were held nearly constant on the basis of the nominal load operation. It was found that the oxygen level was a significant parameter to affect the NOx emission. The impacts of coal properties on NOx emission indicated that NOx emission level decreased with the increase of the ratio of the nitrogen content to low heating value because the volatile matter content in coal significantly influenced the in-flame NOx formation. Coal volatile content was the dominant parameter to affect fuel NOx formation through affecting the reducing condition in the inner near-burner zone when the low NOx burners were applied in the boiler. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Influence of oil-atomized air on flow and combustion characteristics in a 300 MWe down-fired boilerASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2010Zhengqi Li Abstract A method of admitting oil-atomized air into a furnace to adjust coal combustion in a down-fired boiler is described. Experiments with a small-scale furnace simulating a down-fired, pulverized-coal, 300-MWe utility boiler were carried out at a single-phase test facility to investigate the influence of oil-atomized air on the aerodynamic field in the furnace. With the acceleration of oil by secondary air, the primary air/fuel can reach a more distant position with respect to the burner nozzle and the volume of the recirculation zone shrinks. Industrial experiments were also performed in a 300-MWe full-scale boiler. The gas temperature distribution along the primary air/fuel flow in the furnace and the gas components in the near-wall region were measured with the dampers of the oil-atomized air box open and closed. When open, the oil-atomized air does not impede the ignition of the primary air/fuel and can carry the primary air/fuel to a position much deeper in the furnace, resulting in a lowered carbon content in the fly ash. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] An advanced model to assess fouling and slagging in coal fired boilersINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 14 2002Minghou Xu Abstract The assessment of the influence of fouling and slagging on the heat transfer in utility boilers has obtained significant interest both during boiler design and operation. This paper presents a strategy to investigate this influence by introducing heat resistance to represent fouling and slagging on furnace walls. The evaluation of this strategy was performed using the plant heat flux reading data together with a 3-D computational fluid dynamics code. The model considers the influence of the operating conditions to the incident heat fluxes and these are used to assess the heat transfer resistance from the measured absorbed heat fluxes. Copyright © 2002 John Wiley & Sons, Ltd. [source] Partitioning behavior of mercury during coal combustion: the influence of low-NOx burners and operation load of boilerASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2009Guang-Qian Luo Abstract Two 200 MW, pulverized bituminous coal-fired electric utility boilers each equipped with a five-field cold-side electrostatic precipitator (ESP) as the only air pollution control device (APCD) were investigated on mercury distribution and speciation under various conditions. With the same fuel consumption, both facilities are the same but with different burners, low-NOx type and conventional type. Sampling points of gaseous mercury and chlorine species were at the inlet and outlet of the ESP. The mercury concentrations in various solids, including parent coal, bottom slag, economizer bottom ash and fly ash in different hoppers of ESP, were sampled and analyzed. The Ontario Hydro Method was employed to detect mercury in flue gas, and HCl and Cl2 were detected by the EPA method 26. A series of tests were conducted on the boiler with low-NOx burners under various loads (70, 85 and 100% of full load) and on the other boiler with conventional burners under full load. Results showed that small amount of mercury remained in the solid combustion products and most of mercury was released into the atmosphere. The majority of the released mercury was in oxidized form. Burner types and load variation had effects on Cl species concentration in flue gas. Furthermore, particle diameter and carbon content and specific surface area of fly ash affected speciation and distribution of mercury and mercury removal efficiency of ESP. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] | ||||||||||