共查询到20条相似文献,搜索用时 31 毫秒
1.
J. O.L. Wendt C.V. Sternling 《Journal of the Air & Waste Management Association (1995)》2013,63(11):1055-1058
The effect of ammonia in the fuel on NOx emissions was investigated through laboratory experiments and field burner tests. It was found that the degree of conversion of pm-monia to NOx was a strong function of excess air, ammonia content in the fuel, and of the degree of mixing in the flame. In premixed laboratory flames concentrations of NOx above the peak equilibrium amounts were produced. In furnace diffusion flames the conversion to NOx was much less. At substoichiometric air-fuel ratios all the ammonia appears to pyrolize, forming N2, and only very little NOx. Several methods for burning ammonia to produce low NOx emissions were investigated. 相似文献
2.
Daniel Bienstock Robert L. Amsler Edgar R. Bauer Jr. 《Journal of the Air & Waste Management Association (1995)》2013,63(8):442-445
Nitrogen oxides are a potential atmospheric pollutant. Their formation and decomposition were studied in an experimental pulverized-coal-fired furnace. The concentration of nitrogen oxides (NOx) was a maximum in the combustion zone and decreased as the combustion gas cooled. At a coal burning rate of 2 Ib/hr and 22% excess air, reduction of nitrogen oxides was obtained by selective secondary-air distribution. With 105% cf the stoichiometric air fed to the coal-combustion zone and 17% additional air fed just beyond the flame front, 62% reduction of NOx occurred with good combustion efficiency. Lowering the quantity of excess air lowered the NOx concentration, but at the expense of combustion efficiency. When 22% excess air was fed to the primary combustion zone, NOx concentration in the effluent was 550 ppm and carbon in the fly ash 2.0%. With 5% excess air, the NOx concentration fell to 210 ppm and carbon in the fly ash rose to 13.8%. With stoichiometric combustion the NOx was 105 ppm a reduction of 81 %, and the carbon was 42.3%. Recirculation of combustion gas was not an effective means of lowering NOx formation. 相似文献
3.
Qian Zhou Shi-Chune Yao Armistead Russell John Boyle 《Journal of the Air & Waste Management Association (1995)》2013,63(9):1193-1197
A novel technique has been developed for flue gas NOX reduction through the injection of plasma-treated ammonia and its decomposition products. Numerical investigation of the chemical kinetics shows nearly complete NO removal when ammonia radicals are injected into the flue gas. The feasibility of this new technique was experimentally explored on a small-scale laboratory combustor at Carnegie Mellon University and concurrently on a larger-scale combustor at the DOE Pittsburgh Energy Technology Center. Preliminary experimental results have shown that ammonia plasma-injection is more effective than simple ammonia-injection at low flue gas temperatures. NOX reduction of 85 to 90 percent was achieved at a low plasma power input. This technique is expected to provide additional opportunities for inexpensive and effective NOX reduction in stationary sources. 相似文献
4.
Brian K. Gullett Paul W. Groff M. Linda Lin James M. Chen 《Journal of the Air & Waste Management Association (1995)》2013,63(10):1188-1194
Pilot-scale tests were conducted to develop a combined nitrogen oxide (NOx) reduction technology using both selective catalytic reduction (SCR) and selective noncatalytic reduction (SNCR). A commercially available vanadium- and titanium-based composite honeycomb catalyst and enhanced urea (NH2CONH2) were used with a natural-gas-fired furnace at a NOx concentration of 110 ppm. Changes in SNCR chemical injection temperature and stoichiometry led to varying levels of post-furnace ammonia (NH3), which acts as the reductant feed to the downstream SCR catalyst. The urea-based chemical could routinely achieve SNCR plus SCR total NOx reductions of 85 percent with less than 3 ppm NH3 slip at reductant/NOx stoichiometries ranging from about 1.5 to 2.5 and SCR space velocities of 18,000 to 32,000 h?1. This pilot-scale research has shown that SNCR and SCR can be integrated to achieve high NOx removal. SNCR provides high temperature reduction of NOx followed by further removal of NOx and minimization of NH3 slip by a significantly downsized (high-space velocity) SCR. 相似文献
5.
Donald M. Keagy William W. Stalker Charles E. Zimmer Richard C. Dickerson 《Journal of the Air & Waste Management Association (1995)》2013,63(6):270-280
A diffusion flame burner was operated to determine the effect of several parameters on the quantity of NOx and unburned hydrocarbons produced. The statistical analysis indicated the unburned hydrocarbon emissions to be dependent upon the rate of heat release in the system, the amount of excess combustion air, the fuel molecular structure, and the interaction between the fuel structure and the amount of excess air. Analysis of the NOx emissions, after an adjustment to a common temperature to eliminate the temperature effect, showed them to be dependent upon the fuel molecular structure and the amount of excess air. The NOx emissions reached a maximum at the conditions which yielded minimum unburned hydrocarbon emissions. Multiple regressions were made which yielded predicting equations for both the unburned hydrocarbon and the NOx for the apparatus used. 相似文献
6.
《Atmospheric environment (Oxford, England : 1994)》1999,33(10):1587-1598
We evaluated the effect of a 20% reduction in the rate constant of the reaction of the hydroxyl radical with nitrogen dioxide to produce nitric acid (OH+NO2→HNO3) on model predictions of ozone mixing ratios ([O3]) and the effectiveness of reductions in emissions of volatile organic compounds (VOC) and nitrogen oxides (NOx) for reducing [O3]. By comparing a model simulation with the new rate constant to a base case scenario, we found that the [O3] increase was between 2 and 6% for typical rural conditions and between 6 and 16% for typical urban conditions. The increases in [O3] were less than proportional to the reduction in the OH+NO2 rate constant because of negative feedbacks in the photochemical mechanism. Next, we used two different approaches to evaluate how the new OH+NO2 rate constant changed the effectiveness of reductions in emissions of VOC and NOx: first, we evaluated the effect on [O3] sensitivity to small changes in emissions of VOC (d[O3]/dEVOC) and NOx (d[O3]/dENOx); and secondly, we used the empirical kinetic modeling approach to evaluate the effect on the level of emissions reduction necessary to reduce [O3] to a specified level. Both methods showed that reducing the OH+NO2 rate constant caused control strategies for VOC to become less effective relative to NOx control strategies. We found, however, that d[O3]/dEVOC and d[O3]/dENOx did not quantitatively predict the magnitude of the change in the control strategy because the [O3] response was nonlinear with respect to the size of the emissions reduction. We conclude that model sensitivity analyses calculated using small emissions changes do not accurately characterize the effect of uncertainty in model inputs (in this case, the OH+NO2 rate constant) on O3 attainment strategies. Instead, the effects of changes in model inputs should be studied using large changes in precursor emissions to approximate realistic attainment scenarios. 相似文献
7.
Nolan F. Mangelson Laura Lewis Jyothi M. Joseph Wenxuan Cui James Machir Delbert J. Eatough 《Journal of the Air & Waste Management Association (1995)》2013,63(2):167-175
Abstract Air pollutants were collected in Logan, Cache County, UT, in February 1993 during two periods of atmospheric inversion accompanied by fog. The following atmospheric species were determined: (1) gaseous SO2, NO2 (semi-quantitatively),HNO3, NH3, and HF; (2) fine particulate SO4 =, NO3 -, NH4 +, F–, H+, C, Si, S, K, Ca, Ti, Mn, Fe, Ni, Cu, Zn, Pb, Se, Br, and Sr, and; (3) fine particulate mass, which was calculated. The major components of fine particulate matter were carbonaceous material, ammonium nitrate, and ammonium sulfate, while the soil component was small. Calculated, fine particulate mass averaged 80 μg/m3 and reached concentrations as high as 120 μg/m3. SO2/Sox and NO2/NOy mole ratios generally varied between 0.2 and 0.1 during inversions. These ratios also showed moderate but consistent diurnal patterns. The emission inventory for Cache County indicates sources of SO2 and NOx but not significant amounts of primary sulfate and nitrate. The observations reported here indicate there is significant conversion of SO2 and NOx in the presence of excess oxidants to sulfuric and nitric acid that are neutralized by excess ammonia. 相似文献
8.
Pedro A. Sanhueza Gregory D. Reed Wayne T. Davis Terry L. Miller 《Journal of the Air & Waste Management Association (1995)》2013,63(12):1448-1459
Abstract A computer model called the Ozone Risk Assessment Model (ORAM) was developed to evaluate the health effects caused by ground-level ozone (O3) exposure. ORAM was coupled with the U.S. Environmental Protection Agency’s (EPA) Third-Generation Community Multiscale Air Quality model (Models-3/CMAQ), the state-of-the-art air quality model that predicts O3 concentration and allows the examination of various scenarios in which emission rates of O3 precursors (basically, oxides of nitrogen [NOx] and volatile organic compounds) are varied. The principal analyses in ORAM are exposure model performance evaluation, health-effects calculations (expected number of respiratory hospital admissions), economic valuation, and sensitivity and uncertainty analysis through a Monte Carlo simulation. As a demonstration of the system, ORAM was applied to the eastern Tennessee region, and the entire O3 season was simulated for a base case (typical emissions) and three different emission scenarios. The results indicated that a synergism occurs when reductions in NOx emissions from mobile and point sources were applied simultaneously. A 12.9% reduction in asthma hospital admissions is expected when both mobile and point source NOx emissions are reduced (50 and 70%, respectively) versus a 5.8% reduction caused by mobile source and a 3.5% reduction caused by point sources when these emission sources are reduced individually. 相似文献
9.
Ravi K. Srivastava Robert E. Hall Sikander Khan Kevin Culligan Bruce W. Lani 《Journal of the Air & Waste Management Association (1995)》2013,63(9):1367-1388
Abstract Recent regulations have required reductions in emissions of nitrogen oxides (NOx) from electric utility boilers. To comply with these regulatory requirements, it is increasingly important to implement state-of-the-art NOx control technologies on coal-fired utility boilers. This paper reviews NOx control options for these boilers. It discusses the established commercial primary and secondary control technologies and examines what is being done to use them more effectively. Furthermore, the paper discusses recent developments in NOx controls. The popular primary control technologies in use in the United States are low-NOx burners and overfire air. Data reflect that average NOx reductions for specific primary controls have ranged from 35% to 63% from 1995 emissions levels. The secondary NOx control technologies applied on U.S. coal-fired utility boilers include reburning, selective noncatalytic reduction (SNCR), and selective catalytic reduction (SCR). Thirty-six U.S. coal-fired utility boilers have installed SNCR, and reported NOx reductions achieved at these applications ranged from 15% to 66%. Recently, SCR has been installed at >150 U.S. coal-fired utility boilers. Data on the performance of 20 SCR systems operating in the United States with low-NOx emissions reflect that in 2003, these units achieved NOx emission rates between 0.04 and 0.07 lb/106 Btu. 相似文献
10.
Carl Richardson Tom Machalek Scott Miller Chuck Dene Ramsay Chang 《Journal of the Air & Waste Management Association (1995)》2013,63(8):941-947
Abstract The speciation of Hg in coal-fired flue gas can be important in determining the ultimate Hg emissions as well as potential control options for the utility. The effects of NOx control processes, such as selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR), on Hg speciation are not well understood but may impact emissions of Hg. EPRI has investigated the reactions of Hg in flue gas at conditions expected for some NOx control processes. This paper describes the methodology used to investigate these reactions in actual flue gas at several power plants. Results have indicated that some commercial SCR catalysts are capable of oxidizing elemental Hg in flue gas obtained from the inlets of SCR or air heater units. Results are affected by various flue gas and operating parameters. The effect of flue gas composition, including the presence of NH3, has been evaluated. The influence of NH3 on fly ash Hg reactions also is being investigated. 相似文献
11.
Mindong Bai Zhitao Zhang Hong Leng Xiyao Bai Chengwu Yi 《Journal of the Air & Waste Management Association (1995)》2013,63(7):854-860
ABSTRACT This paper presents a technique for the complete, simultaneous decomposition of CO2, SO2, and NOx, as well as the simultaneous removal of fly ash by ultra-high voltage pulse activation. Ultra-high voltage narrow pulse is used to make the gases in the reactor become active molecules, which are then dissociated into nonpoisonous gas molecules and solid particles under the control of a directional reaction model. By using a sufficient charge and a strong electric field, the fly ash can be removed. It becomes the carrier of C and S, and its efficiency is 99.5%. Owing to the action of catalyst B (using Ni as the mother's body), the activation energy of CO2, SO2, and NOx gases is reduced in great magnitude, and their removal efficiency can reach 75~90% at normal pressure and 180 °C. 相似文献
12.
Maria Jędrusik Arkadiusz Świerczok Mieczysław Adam Gostomczyk Mariola Kobylańska-Pawlisz 《Journal of the Air & Waste Management Association (1995)》2020,70(6):629-640
ABSTRACT
This article presents the results of an industrial-scale study (on 400 MWe lignite fired unit) of simultaneous NOx, SO2, and HgT removal in FGD absorber with oxidant injection (NaClO2) into flue gas. It was confirmed that the injection of sodium chlorite upstream the FGD (Flue Gas Desulfurization) absorber oxidize NO to NO2, Hg0 to Hg2+, and enhancing NOx and HgT removal efficiency from exhaust gas in FGD absorber. Mercury removal efficiency grows with the rise of degree of oxidation NO to NO2 and was limited by the phenomenon of re-emission. For NOx removal the most critical parameters is slurry pH and temperature. There was no negative effect on sulfur dioxide removal efficiency caused by oxidant injection in tested FGD absorber. Based on the data provided, NOx and HgT emissions can be reduced by adjusting the FGD absorber operating parameters combined with oxidant injection. 相似文献
13.
Ma Lefan Tong Zhiquan Zhang Junfeng 《Journal of the Air & Waste Management Association (1995)》2013,63(12):1543-1549
Abstract A novel process for removal of nitrogen oxides (NOx) from flue gases with iron filings reduction following complex absorption in iron-ethylenediaminetetraacetic acid aqueous solution is proposed. The reaction mechanism involved in the process is discussed briefly. The parameters influencing the process, including the concentration of ferrous chelates, initial pH, amount of iron filings, temperature, flow rate of the flue gas, and inlet nitric oxide concentration and oxygen content of the flue gas, are researched in detail. The optimal NOx removal conditions are established. The regeneration and circular utilization of the absorption solution also is studied. 相似文献
14.
《Atmospheric environment(England)》1984,18(12):2585-2593
NO, NO2 and total reactive nitrogen, NOy, were measured using chemiluminescence throughout the troposphere. Flights were made from Frankfurt (West Germany) to Abu Dhabi (United Arab Emirates), and from Frankfurt to Sao Paulo (Brazil). NOx (NO + NO2) concentrations were determined with a FeSO4 converter and noy, with a 425°C Mo converter. NOx levels over the Northern Hemisphere at 9 km altitude were about 200 ppt. On one flight over central Europe the aircraft encountered a thunderstorm system over an area 600km wide. NOy, was markedly elevated in the area of these thunderstorms due, we believe, to the rapid transport of polluted boundary layer air into the upper troposphere. The long lifetime of these trace gases in the upper troposphere allows them to be transported to the remote atmosphere where photolysis and radical reactions could produce significant quantities of ozone. The NOy concentration of 3.5 (+0.7−0.9) ppb was significantly higher than the concentration of about 190 ppt measured on a separate flight. These and NOx data indicate that tropospheric reactive nitrogen species vary widely in concentration, and a ‘representative’ distribution may not exist. 相似文献
15.
Charles L. Blanchard Shelley J. Tanenbaum 《Journal of the Air & Waste Management Association (1995)》2013,63(7):816-828
Abstract Ambient air quality data were analyzed to empirically evaluate the effects of reductions of volatile organic compounds (VOCs) and oxides of nitrogen (NOx) emissions on weekday and weekend levels of ozone (O3; 1991–1998) and particulate NO3 - (1980–1999) in southern California. Despite significantly lower O3 precursor levels on weekends, 20 of 28 South Coast Air Basin (SoCAB) sites (28 of all 78 southern California sites) showed statistically significant higher mean O3 levels on Sundays than on weekdays (p < 0.01); 49 of the remaining 50 sites showed no significant differences between mean weekday and Sunday peak O3 levels. We also observed no statistically significant differences between mean weekday and weekend concentrations of particulate NO3 - or nitric acid (HNO3, the precursor of particulate NO3 -). Averaged over sites, the mean Sunday NOx and nonmethane hydrocarbon concentrations were 25–41% and 16–30% lower, respectively, than on weekdays. Site-to-site differences between weekend and weekday mean peak hourly O3 levels were related to whether O3 formation was limited by the availability of NOx. A thermodynamic equilibrium model predicts that particulate NO3 - levels would decrease in response to a reduction of HNO3, and that particulate ammonium NO3 - formation was not limited by the availability of ammonia. The similarity of mean weekday and weekend levels of NO3 - therefore did not result from limitations on the formation of particulate NO3 - from its precursor, HNO3. 相似文献
16.
ABM S. Khan Nigel N. Clark Gregory J. Thompson W. Scott Wayne Mridul Gautam Donald W. Lyon 《Journal of the Air & Waste Management Association (1995)》2013,63(10):1404-1419
Abstract Heavy-duty diesel vehicle idling consumes fuel and reduces atmospheric quality, but its restriction cannot simply be proscribed, because cab heat or air-conditioning provides essential driver comfort. A comprehensive tailpipe emissions database to describe idling impacts is not yet available. This paper presents a substantial data set that incorporates results from the West Virginia University transient engine test cell, the E-55/59 Study and the Gasoline/Diesel PM Split Study. It covered 75 heavy-duty diesel engines and trucks, which were divided into two groups: vehicles with mechanical fuel injection (MFI) and vehicles with electronic fuel injection (EFI). Idle emissions of CO, hydrocarbon (HC), oxides of nitrogen (NOx), particulate matter (PM), and carbon dioxide (CO2) have been reported. Idle CO2 emissions allowed the projection of fuel consumption during idling. Test-to-test variations were observed for repeat idle tests on the same vehicle because of measurement variation, accessory loads, and ambient conditions. Vehicles fitted with EFI, on average, emitted [~20 g/hr of CO, 6 g/hr of HC, 86 g/hr of NOx, 1 g/hr of PM, and 4636 g/hr of CO2 during idle. MFI equipped vehicles emitted ~35 g/hr of CO, 23 g/hr of HC, 48 g/hr of NOx, 4 g/hr of PM, and 4484 g/hr of CO2, on average, during idle. Vehicles with EFI emitted less idleCO, HC, and PM, which could be attributed to the efficient combustion and superior fuel atomization in EFI systems. Idle NOx, however, increased with EFI, which corresponds with the advancing of timing to improve idle combustion. Fuel injection management did not have any effect on CO2 and, hence, fuel consumption. Use of air conditioning without increasing engine speed increased idle CO2, NOx, PM, HC, and fuel consumption by 25% on average. When the engine speed was elevated from 600 to 1100 revolutions per minute, CO2 and NOx emissions and fuel consumption increased by >150%, whereas PM and HC emissions increased by ~100% and 70%, respectively. Six Detroit Diesel Corp. (DDC) Series 60 engines in engine test cell were found to emit less CO, NOx, and PM emissions and consumed fuel at only 75%of the level found in the chassis dynamometer data. This is because fan and compressor loads were absent in the engine test cell. 相似文献
17.
Walter A. Baxter 《Journal of the Air & Waste Management Association (1995)》2013,63(12):817-820
Motivated by heightened recent interest, Koppers Co. has been experimenting with ammonia conditioning of power boiler flue gases for the purpose of improving the precipitability of the emitted fly ash. Chemical reactions resulting from ammonia injection are postulated. Measurements on three pulverized coal and two cyclone fired boilers, all of which emit acidic ash, are described. In all five cases, considerable but varying, increase in precipitator power input and collection efficiency resulted when gaseous ammonia in the amount of 1 5 ppm was injected between the economizer and air preheater. The conditioned fly ash showed decreased acidity and inconsistent change in electrical resistivity. Unless air heater temperatures were unusually high (>400°F), tendency of the air heater to plug was an additional, but unwanted, result. At one station with high air heater outlet temperature ammonia injection has been adopted as a permanent solution to community pressure for reduction of stack discharge. Ammonia injection downstream of the air heater produced no effect. Future plans are presented to continue the program beyond results described here. 相似文献
18.
《Atmospheric environment(England)》1986,20(4):665-680
A coupled one-dimensional radiative-convective and photochemical diffusion model (RCP model), which takes into account the interaction of ozone photochemistry on climate, is used to investigate the possible effects of smoke and NOx generated by a large-scale nuclear war, on vertical temperature and ozone structure and surface climate. From the results of initial experiments with fixed O3 it is found that for the nuclear smoke injection scenario adopted in this study (similar to the base line case of Turco etal., 1983), the average sunlight intensities would be reduced drastically (up to 97%), leading to a large cooling near the surface (up to 38 K) and intense heating (up to 110 K) in the upper troposphere and lower stratosphere. Variation of surface albedo, water vapour and clouds with time following the smoke injection would further enhance the surface cooling and prolong the temperature perturbation.Further experimental results with O3 photochemistry interaction indicate that for the smoke and NOx nuclear injection scenario considered in this study, the total O3 column would decrease up to 50%, with a half recovery time of about 2 y. However more than half the total O3 column reduction is caused by the heating of the stratosphere by smoke injection. The effect of stratospheric O3 reductions on surface climate is not significant (less than 2.5 K. additional cooling). However the vertical temperature profile is altered in such a way that it would lead to a large increase in the thermal stability of the troposphere, while decreasing it in the stratosphere more than in the case of fixed O3. Also discussed are the solar u.v.-B flux changes at the surface which result from the presence of smoke in the atmosphere initially and from stratospheric O3 depletions as the smoke particles are removed from the atmosphere in time. 相似文献
19.
Jochen Stutz Kam Weng Wong Laura Lawrence Luke Ziemba James H. Flynn Bernhard Rappenglück Barry Lefer 《Atmospheric environment (Oxford, England : 1994)》2010,44(33):4099-4106
Radical chemistry in the nocturnal urban boundary layer is dominated by the nitrate radical, NO3, which oxidizes hydrocarbons and, through the aerosol uptake of N2O5, indirectly influences the nitrogen budget. The impact of NO3 chemistry on polluted atmospheres and urban air quality is, however, not well understood, due to a lack of observations and the strong impact of vertical stability of the boundary layer, which makes nocturnal chemistry highly altitude dependent.Here we present long-path DOAS observations of the vertical distribution of the key nocturnal species O3, NO2, and NO3 during the TRAMP experiment in Summer 2006 in Houston, TX. Our observations confirm the altitude dependence of nocturnal chemistry, which is reflected in the concentration profiles of all trace gases at night. In contrast to other study locations, NO3 chemistry in Houston is dominated by industrial emissions of alkenes, in particular of isoprene, isobutene, and sporadically 1,3-butadiene, which are responsible for more than 70% of the nocturnal NO3 loss. The nocturnally averaged loss of NOx in the lowest 300 m of the Houston atmosphere is ~0.9 ppb h?1, with little day-to-day variability. A comparison with the daytime NOx loss shows that NO3 chemistry is responsible for 16–50% of the NOx loss in a 24-h period in the lowest 300 m of the atmosphere. The importance of the NO3 + isoprene/1,3-butadiene reactions implies the efficient formation of organic nitrates and secondary organic aerosol at night in Houston. 相似文献
20.
《Atmospheric environment(England)》1981,15(5):743-747
Precursor concentration distributions have been reported for Sydney (Post, 1979a) and the implications of these data for ozone control (namely NMHC emission reduction) have been presented elsewhere (Post, 1979a, b). In this analysis, a number of relationships between non-methane hydrocarbon (NMHC) concentration, nitrogen oxides (NOx concentration, NMHC/NOx ratio and the ozone formation potential parameter (NOx × (NMHC) are constructed from the field data. These relationships show that:
- 1.(i) NMHC emissions into the Sydney airshed are less uniformly distributed than NOx emissions and generate air parcels with higher than “typical” NMHC/NOx, ratio.
- 2.(ii) Air parcels with higher than “typical” NMHC/NOx ratio are generally those with the worst (highest) ozone formation potential.