Home About us Contact
|
Home About us Contact | ||
|
|
||
Flue Gases (flue + gase)
Selected AbstractsPilot scale SO2 control by dry sodium bicarbonate injection and an electrostatic precipitatorENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 3 2007Michael J. Pilat Abstract A 500 actual cubic feet gas per minute (acfm) pilot-scale SO2 control study was undertaken to investigate flue gas desulfurization (FGD) by dry sodium sorbents in 400°F (204.5°C) flue gases emitted from a coal fired boiler with flue gas concentrations between 350 and 2500 ppm SO2. Powdered sodium alkaline reagents were injected into the hot flue gas downstream of the air preheater and the spent reagents were collected using an electrostatic precipitator. Three different sorbents were used: processed sodium bicarbonate of two particle sizes; solution mined sodium bicarbonate, and processed sodium sesquicarbonate. SO2 concentrations were measured upstream of the reagent injection, 25-ft (7.62 m) downstream of the injection point, and downstream of the electrostatic precipitator. SO2 collection efficiencies ranged from 40 to 80% using sodium bicarbonate stoichiometric ratios from 0.5 to 3.0. Much of the in-duct SO2 removal occurred during the first second of reagent reaction time, indicating that the sulfur dioxide,sodium reaction rates may be faster than have been measured for fixed bed measurements reported in the literature. © 2007 American Institute of Chemical Engineers Environ Prog, 2007 [source] Measurements 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] Bioprocesses for the removal of nitrogen oxides from polluted airJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2005Yaomin Jin Abstract Nitrogen oxides (NOx) of environmental concern are nitrogen monoxide (NO) and nitrogen dioxide (NO2). They are hazardous air pollutants that lead to the formation of acid rain and tropospheric ozone. Both pollutants are usually present simultaneously and are, therefore, called NOx. Another compound is N2O which is found in the stratosphere where it plays a role in the greenhouse effect. Concern for environmental and health issues coupled with stringent NOx emission standards generates a need for the development of efficient low-cost NOx abatement technologies. Under such circumstances, it becomes mandatory for each NOx-emitting industry or facility to opt for proper NOx control measures. Several techniques are available to control NOx emissions: selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR), adsorption, scrubbing, and biological methods. Each process offers specific advantages and limitations. Since bioprocesses present many advantages over conventional technologies for flue gas cleaning, a lot of interest has recently been shown for these processes. This article reviews the major characteristics of conventional non-biological technologies and recent advances in the biological removal of NOx from flue gases based on the catalytic activity of either eucaryotes or procaryotes, ie nitrification, denitrification, the use of microalgae, and a combined physicochemical and biological process (BioDeNOx). Relatively uncomplicated design and simple operation and maintenance requirements make biological removal a good option for the control of NOx emissions in stationary sources. Copyright © 2005 Society of Chemical Industry [source] Molecular simulation of separation of CO2 from flue gases in CU-BTC metal-organic frameworkAICHE JOURNAL, Issue 11 2007Qingyuan Yang Abstract In this work, a computational study was performed on the adsorption separation of CO2 from flue gases (mixtures of CO2/N2/O2) in Cu-BTC metal-organic framework (MOF) to investigate the applicability of MOFs to this important industrial system. The computational results showed that Cu-BTC is a promising material for separation of CO2 from flue gases, and the macroscopic separation behaviors of the MOF were elucidated at a molecular level to give insight into the underlying mechanisms. The present work not only provided useful information for understanding the separation characteristics of MOFs, but also showed their potential applications in chemical industry. © 2007 American Institute of Chemical Engineers AIChE J, 2007 [source] A novel continuous reactor for catalytic reduction of NOx,fixed bed simulationsTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2008Terris T. Yang Abstract A novel dual-zone fluidized bed reactor was proposed for the continuous adsorption and reduction of NOx from combustion flue gases. The adsorption and reaction behaviour of such a reactor has been simulated in a fixed bed reactor using Fe/ZSM-5 catalyst and propylene reductant with model flue gases. Fe/ZSM-5 exhibited acceptable activity at T,=,350°C and GHSV,=,5000 h,1 when O2 concentration was controlled at levels lower than 1% with a HC to NO molar ratio of about 2:1. XPS and BET surface area measurement revealed the nature of the deactivation of the catalyst. Those performance data demonstrated the feasibility of a continuous dual-zone fluidized bed reactor for catalytic reduction of NOx under lean operating conditions. Un nouveau réacteur à lit fluidisé à double zone est proposé pour l'adsorption et la réduction en continu de NOx à partir de gaz de carneau de combustion. Le comportement d'adsorption et de réaction d'un tel réacteur a été simulé dans un réacteur à lit fixe utilisant un catalyseur Fe/ZSM-5 et un agent réducteur avec des gaz de carneau modèle. Le Fe/ZSM-5 montre une activité acceptable à T,=,350°C et GHSV,=,5000 h,1 lorsque la concentration d'O2 est contrôlée à des niveaux inférieurs à 1% avec un rapport molaire HC,NO d'environ 2:1. La mesure de surface par XPS et BET a permis de caractériser la désactivation du catalyseur. Ces données de performance illustre la faisabilité du réacteur à lit fluidisé à double zone Fe/ZSM-5 pour la réduction catalytique de NOx dans des conditions opératoires pauvres. [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] The Oxidation Kinetics of Mercury in Hg/O/H/Cl SystemASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3-4 2005Y. Qiao The potential for regulation of mercury emission from coal-fired boilers is a concern for the electric utility industry. Field data show a wide variation in the fraction of mercury that is emitted as a vapor versus that retained in the solid products. The reason for this variation is not well understood. Near the end of the flue gas path, mercury exists as a combination of elemental vapor and HgCl2 vapor. The data show that HCl2 is more likely to be removed form the flue gas. The need to describe accurately mercury reaction products and their concentration-time correlation prompted investigation of mercury chemical kinetic mechanisms and their application to real combustion systems. This paper uses chemical equilibrium analysis to study the speciation of mercury in flue gases during coal combustion and gasification. The paper presents a simple kinetic model of mercury oxidation in the Hg/O/H/Cl system. The results porn the model calculation are in reasonable agreement with the Mamani-Paco and Heleble [1] experimental data [source] | |||||||||||||