Download or read book A Study of NO subscript X Reduction by Fuel Injection Recirculation Final Report January 1995 June 1996 written by and published by . This book was released on 1996 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flue-gas recirculation (FGR) is a well-known method used to control oxides of nitrogen (NO(subscript x)) in industrial burner applications. Recent small- and large-scale experiments in natural-gas fired boilers have shown that introducing the recirculated flue gases with the fuel results in a much greater reduction in NO(subscript x), per unit mass of gas recirculated, in comparison to introducing the flue gases with the combustion air. That fuel injection recirculation (FIR) is more effective than windbox FGR is quite remarkable. At present, however, there is no definitive understanding of why FIR is more effective than conventional FGR. The objective of the present investigation is to ascertain whether or not chemical and/or molecular transport effects alone can explain the differences in NO(subscript x) reduction observed between FIR and FGR by studying laminar diffusion flames. The purpose of studying laminar flames is to isolate chemical effects from the effects of turbulent mixing and heat transfer, which are inherent in practical boilers. The results of both the numerical simulations and the experiments suggest that, although molecular transport and chemical kinetic phenomena are affected by the location of diluent addition depending on flow conditions, the greater effectiveness of FIR over FGR in practical applications may result from differences in turbulent mixing and heat transfer. Further research is required to understand how differences in diluent-addition location affect NO(subscript x) production in turbulent flames. The present study, however, provides an underlying basis for understanding how flow conditions can affect flame chemistry. 51 figs., 7 tabs.
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Download or read book A Study of NOsub X Reduction by Fuel Injection Recirculation Topical Report January 1995 May 1995 written by and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Study of NO subscript X Reduction by Fuel Injection Recirculation written by and published by . This book was released on 1996 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flue-gas recirculation (FGR) is a well-known method used to control oxides of nitrogen (NO{sub X}) in industrial burner applications. Recent small- and large-scale experiments in natural-gas fired boilers have shown that introducing the recirculated flue gases with the fuel results in a much greater reduction in NO{sub X}, per unit mass of gas recirculated, in comparison to introducing the flue gases with the combustion air. That fuel injection recirculation (FIR) is more effective than windbox FGR is quite remarkable. At present, however, there is no definitive understanding of why FIR is more effective than conventional FGR. The objective of the present investigation is to ascertain whether or not chemical and/or molecular transport effects alone can explain the differences in NO{sub X} reduction observed between FIR and FGR by studying laminar diffusion flames. The purpose of studying laminar flames is to isolate chemical effects from the effects of turbulent mixing and heat transfer, which are inherent in practical boilers. Numerical simulations of H2-air and CH4-air counterflow diffusion flames using full kinetics were performed and NO{sub X} emission indices calculated for various conditions. Studies were conducted in which a N2 diluent was added either on the fuel- or air-side of the flame for conditions of either fixed initial velocities or fixed fuel mass flux. Results from these simulation studies indicate that a major factor in diluent effectiveness is the differential effect on flame zone residence times associated with fuel-side verses air-side dilution. Simulations in which flow velocities were fixed as diluent was added either to the air or fuel stream showed lower NO{sub X} emissions for air-side dilution; however, if instead, fuel mass fluxes were fixed as diluent was added, which results in an increase in the velocity of the streams, fuel-side dilution was more effective. These results were independent of whether H2 or Ch4 was used as the fuel.
Download or read book A Study of NOsub X Reduction by Fuel Injection Recirculation Topical Report June December 1995 written by and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NO subscript X Emission Controls for Heavy duty Vehicles written by National Research Council (U.S.). Motor Vehicle Nitrogen Oxides Standard Committee and published by National Academies. This book was released on 1981 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Computational Modeling and Experimental Studies on NO subscript X Reduction Under Pulverized Coal Combustion Conditions Technical Progress Report Second Quarter April 1 1995 June 30 1995 written by and published by . This book was released on 1995 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presented in this second quarterly report are the computational results of NO reburning with (a) a combination of methane and acetylene (i) with the reaction mechanism listed in the first quarterly report and (ii) with the updated reaction mechanism (Table 1 of this report); and (b) a combination of methane and ammonia. The impact of the updated reaction scheme was not significant on the results of NO reburning with methane/acetylene; however, the reaction scheme needed changes to improve the accuracy of some reactions of crucial intermediates in methane/ammonia reburning. An extensive literature survey was made in order to update the mechanism.
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Download or read book Computational Modeling and Experimental Studies on NO subscript X Reduction Under Pulverized Coal Combustion Conditions Technical Progress Report Sixth Quarter April 1 June 30 1996 written by and published by . This book was released on 1996 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: During this quarter, the experiments for nitric oxide reburning with a combination of methane and acetylene were conducted successfully. With the failure of ozonator lamp in the NOx analyzer shortly thereafter, the experimental study of nitric oxide reburning with a combination of methane and ammonia could not be completed. In the meantime, a coal feeder was designed and a purchase order was sent out for the building of the coal feeder. Presented herein are the experimental results of NO reburning with methane/acetylene. The results are consistent with model predictions.
Download or read book Kinetics and Mechanisms of NO subscript X written by and published by . This book was released on 1995 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: This project is concerned with the mechanism of reduction of both NO and N2O by carbons. It was recognized some years ago that NO formed during fluidized bed coal combustion can be heterogeneously reduced in-situ by the carbonaceous solid intermediates of combustion. This has been recently supplemented by the knowledge that heterogeneous reaction with carbon can also play an important role in reducing emissions of N2, but that the NO-carbon reactions might also contribute to formation of N2. The precise role of carbon in N2 reduction and formation has yet to be established. Interest in the N2 and N2O-char reactions has been significant in connection with both combustor modeling, as well as in design of post-combustion NO(subscript x) control strategies. In our studies, a DuPont thermogravimetric analyzer (TGA) is used for the char reactivity studies. The temperature and mass are recorded as function of time, using a Macintosh computer and software for simultaneous apparatus control and data acquisition. Specific surface areas of char samples were determined by the N2 BET method at 77 K.A standard flow-type adsorption device (Quantasorb) was used for the measurements. Prior to surface area analysis, all samples were outgassed in a flow of nitrogen at 573 K for 3 hours. The carbonaceous solids used were resin char, graphite, coconut char and a Wyodak coal char. As was noted in the last report, carbons derived from different original materials show quite similar behaviors, in terms of the trends, but there are significant differences in actual reaction rates. It was shown that the spread of the reaction rate data from different studies, when expressed on a mass of carbon reactant- or surface area-basis, was almost the same.
Download or read book An Experimental Study of NO subscript X Recycle in the NOXSO Flue Gas Cleanup Process Quarterly Technical Progress Report April 1 June 31 1992 written by and published by . This book was released on 1992 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: NO(subscript x) recycle is one part of the NOXSO process. In this process, 90% of the acid pollutants (NO(subscript x) and SO2) can be removed simultaneously by adsorption on the surface of a sorbent material. The sorbent is subsequently regenerated by heating and contacting the hot sorbent with a reducing gas followed by steam. The NO(subscript x) is removed in the heating process, and the SO2 is removed by the chemical reaction of the reducing gas and steam. The NO(subscript x) stream produced is returned to the combustion process with combustion air, which is called the NO(subscript x) recycle. The NO(subscript x) is reduced in the flame to N2, H2O, and CO2. The tests of NO injection with combustion have demonstrated very promising results. The test data showed quite consistent NO(subscript x) reduction efficiencies, which is similar to the previous test results on the pulverized coal combustor at DOE-PETC. An average of about 70 % NO. destruction efficiency was achieved for the NO injection into the primary air duct independent of injected NO flow rates and exit 02 concentrations. About 58%, 50%, and 46% average destruction efficiencies were obtained for the NO injection into the secondary air duct corresponding to the exit O2concentrations of 2%, 3%, and 4% respectively.
Download or read book Summary of Meetings 14 October 1998 written by and published by . This book was released on 1998 with total page 2 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Study of NO subscript X Recycle in the NOXSO Flue Gas Cleanup Process Quarterly Technical Progress Report October 1 December 31 1992 written by and published by . This book was released on 1992 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: All the tests planed were completed. NO2 injection tests showed higher NO(subscript x) reduction than that of NO injection at similar testing conditions. The NO(subscript x) reduction efficiency for the NO/NO2 mixture injection is higher than that for NO injection and lower than that for NO2 injection separately. The NO(subscript x) reduction efficiency is independent on the amount of injected gas (NO, NO2, or NO/NO2), but affected by the exit O2. The optimum injection location which gives higher NO(subscript x) reduction efficiency is the primary air duct. The NO(subscript x) reduction efficiency increases with the percentage of total NO injected into the primary air duct when injecting NO into both primary air duct and secondary air duct simultaneous.
Download or read book Kinetics and Mechanisms of NO subscript X Char Reduction Quarterly Technical Progress Report May 1 1995 July 31 1995 written by and published by . This book was released on 1995 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: The emission of nitrogen oxides from combustion of coal remains a problem of considerable interest, whether the concern is with acid rain, stratospheric ozone chemistry, or {open_quotes}greenhouse{close_quotes} gases. Whereas earlier the concern was focused mainly on NO (as a primary combustion product) and to a lesser extent NO2 (since it is mainly a secondary product of combustion), in recent years the emissions of N2O have also captured considerable attention, particularly in the context of fluidized bed combustion, in which the problem appears to be most acute. The research community has only recently begun to take solid hold on the N2O problem. This is in part because earlier estimates of the importance of N2O in combustion processes were clouded by artifacts in sampling which have now been resolved. This project is concerned with the mechanism of reduction of both NO and N2O by carbons. It was recognized some years ago that NO formed during fluidized bed coal combustion can be heterogeneously reduced in-situ by the carbonaceous solid intermediates of combustion. This has been recently supplemented by the knowledge that heterogeneous reaction with carbon can also play an important role in reducing emissions of N2O, but that the NO-carbon reactions might also contribute to formation of N2O. The precise role of carbon in N2O reduction and formation has yet to be established, since in one case the authors of a recent study were compelled to comment that {open_quotes}the basic knowledge of N2O formation and reduction still has to be improved{close_quotes}. The same can be said of the NO-carbon system. In this program, carbons studied include graphite, resin char, coconut char, and a Wyodak coal char.
Download or read book Kinetics and Mechanisms of NO subscript X Char Reduction Quarterly Technical Progress Report 1 May 1996 31 July 1996 written by and published by . This book was released on 1997 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: The emission of nitrogen oxides from combustion of coal remains a problem of considerable interest, whether the concern is with acid rain, stratospheric ozone chemistry, or {open_quotes}greenhouse{close_quotes} gases. Whereas earlier the concern was focused mainly on NO (as a primary combustion product) and to a lesser extent NO2, in recent years the emissions of N2O have also captured considerable attention, particularly in the context of fluidized bed combustion, in which the problem appears to be most acute. The research community has only recently begun to take solid hold on the N2O problem. This is in part because earlier estimates of the importance of N2O in combustion processes were clouded by artifacts in sampling which have now been resolved. This project is concerned with the mechanism of reduction of both NO and N2O by carbons.
Download or read book Nitrogen Oxide Abatement by Distributed Fuel Addition Quarterly Report No 2 November 1 1987 January 31 1988 written by and published by . This book was released on 1988 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this project is to develop techniques for nitrogen oxides abatement by distributed fuel addition. The major nitrogen oxide of interest is Nitric Oxide (NO), a precursor to premature forest damage and to acid rain. Recently interest has also been evoked with respect to an additional oxide of nitrogen, namely Nitrous Oxide (N2O). Therefore, abatement measures for NO(subscript x) are being investigated to determine their influence on N2O as well. This report briefly describes the significance of N2O emissions to the environment and the urgent need to develop techniques that can reduce emissions of both NO and N2O. Reburning through distributed fuel addition may be an effective technique for NO(subscript x) (mainly NO) emission control as described in the previous quarterly report. Reburning may also be effective in reducing N2O levels. A technique for N2O measurement by gas chromatography/electron capture detection was developed during this quarter, and is described in this report. This analysis technique will be used in the proposed experimental study to investigate the effectiveness of reburning on N2O control.
Download or read book NO subscript X Reduction in Pressurized Fluidized bed Combustion written by and published by . This book was released on 1992 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Batch combustion experiments were performed in a small bubbling fluidized-bed reactor with the objective of establishing the cause of reduced NO(subscript x) emissions from pressurized fluidized bed combustion (PFBC). All variables except for pressure were kept constant in the experiments: fuel batch size, for example, was the same in experiments performed at three pressure levels (0.2, 1 and 2 MPa). Two different types of experiments were conducted: one using air diluted with nitrogen (4.5% O2) for the purpose of determining the conversion of fuel N to NO(subscript x), and the other with NO-doped diluted air (800 ppM NO, 4.5% O2) for the purpose of determining the reduction of bulk-gas NO(subscript x) by the burning fuel. A large excess of combustion air was used in all experiments so as to keep the bulk-gas composition relatively unchanged by combustion products. Six different fuels were studied: a bituminous coal, coke prepared from the same coal, three specialty cokes (one of which contained 10 wt % N) and graphite (0%N). The straight-air combustion experiments showed that the conversion of fuel-N to NO(subscript x) dropped with increasing pressure (at constant fuel concentration in the bed). The NO-doped combustion experiments showed significantly increased NO(subscript x) reduction with increased pressure. This effect was particularly strong between 0.2 and 1 MPa, and was found to continue between 1 and 2 MPa for some of the fuels but too saturate for others. These results imply that an important phenomenon for low PFBC NO(subscript x) emission is the reaction of NO(subscript x) with reducing N-containing species at the burning fuel surfaces. A simple kinetic model involving parallel paths for the fuel-N is suggested as an interpretation of the results. The NO-doped experiments showed increased N2O formation relative to the straight-air experiments implying that N2O was a byproduct of the NO(subscript x) reduction reaction where N2 was the main product.
