Download or read book Role of Char During Reburning of Nitrogen Oxides Seventh Quarterly Progress Report April 1 1995 June 30 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 Role of Char During Reburning of Nitrogen Oxides Eighth Quarterly Report July 1 1995 September 30 1995 written by and published by . This book was released on 1995 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt: The investigation of this quarter focuses on the rates of NO reactions with chars in various gaseous environments. The results have revealed significant insights into the NO reduction mechanisms on char surface, particularly when the oxidants, O2 and CO2, are introduced into the feed. Indeed, evidences suggest that the formation of stable oxygen complexes is the major cause of differences in NO reactivity on chars of different origins. The oxidants retard the reactivity of char derived fro the bituminous coal more seriously than they affect the char derived from lignite. Furthermore, additions of these oxidants into the reacting stream produce additional yields of CO and CO2 during NO reaction with lignite char, suggesting gasification of carbon from lignite char. No excess CO and CO2 were observed when the bituminous coal char was used. These yields of CO and CO2 also imply that desorption of stable surface oxygen complex is a rate-limiting step which may be catalyzed by the mineral matters during reactions involving lignite char. Surface area evaluated by CO2 and Dubinin-Radushkevich (D-R) equation is not a normalization factor of char reactivity during reburning. In the absence of oxidants, the bituminous coal char shows drastic increase in activation energy at about 950 °C indicating transition of desorption to adsorption controlled mechanisms. When CO2 is introduced, the transition temperature increases. When oxygen is also added, no such transition is observed up to 1100 °C. Lignite char reactivity increases smoothly over the temperature range 800 to 1100 °C. It is also observed that char reactivity decreases with increasing pyrolysis temperature which may be caused by closure of pores due to graphitization. The rate of NO reduction on the Pittsburgh {number_sign}8 coal char is then in good accord with that of a West Virginia coal char reported by De Soete (1980).

Download or read book Role of Char During Reburning of Nitrogen Oxides Ninth Quarterly Report October 1 1995 December 31 1995 written by and published by . This book was released on 1996 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: During this quarter, we have investigated rates and product compositions of NO reduction on chars in gases. N2 and CO2 internal surface areas of chars, selected from runs of various pyrolysis and reaction conditions have been measured to assist in interpreting the experimental results. Implications of Langmuir- Hinshelwood mechanisms and mass transfer limitations were examined. Oxidants suppress NO reduction on bituminous coal char more than on lignite char. Observations suggest that NO adsorption and desorption of stable surface oxygen complexes are potentially important rate- limiting steps and may be catalyzed by mineral matter during reburning with lignite char. Relative inert nature of lignite char to CO2 presence may have potential value in use of fuel system involving both solid and volatile fuels. Lignite char produced at 950 C and zero holding time has higher reactivity than that produced at 1100 C and 5 min holding time. Bituminous coal chars produced at these two conditions, however, have similar reactivity with NO. Internal surface areas of both type chars vary with pyrolysis conditions and gas composition in the subsequent reaction. When oxidants are introduced in the feed, internal surface areas of these two chars vary in opposite directions.

Download or read book Government Reports Announcements Index written by and published by . This book was released on 1996 with total page 814 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Role of Char During Reburning of Nitrogen Oxides Sixth Quarterly Report January 1 1995 March 31 1995 written by and published by . This book was released on 1995 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book La cerisaie mise en sc ne de Peter Brook et Maurice Benichou written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Research Abstracts written by and published by . This book was released on 1995 with total page 782 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Role of Char During Reburning of Nitrogen Oxides written by and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Role of Char During Reburning of Nnitrogen Oxides Second Quarterly Report 1996 written by and published by . This book was released on 1996 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reburning is an emerging three-stage combustion technology designed for the reduction of NO by introducing a small amount of reburning fuel above the primary flame where the majority of NO is chemically reduced to nitrogen. While coal, in general, has not been considered an effective reburning fuel, research at the University of Mississippi suggested that lignite has a reburning efficiency even higher than that of methane. Furthermore, heterogeneous mechanisms are more important than homogeneous mechanisms for char/NO reaction. The objectives of this research are to investigate: (1) implications of pore structure analysis, (2) parameters governing heterogeneous reactions, and (3) estimation of rates of NO reduction and mass transfer limitations. Experiments have been performed in a flow reactor with a simulated fuel gas at a stoichiometric ratio (SR) 1.1. Reburning fuels in this study include chars derived from Pittsburgh No. 8 bituminous coal and Mississippi lignite. Chars were produced in N2 by suspending a sample basket in a tube furnace. Pore structure analyses include BET-N2, BET-CO2, and DR-CO2 surface pore size distribution, micropore volume, total pore volume, and average pore radius. These studies suggest that neither BET-N2 nor DR- CO2 surface area is a normalization factor of chars of different origin. Reaction with NO leads to closures of pores, which may be contributed by formation of surface complexes.

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Download or read book Role of Char During Reburning of Nitrogen Oxides First Quarterly Report October 1 1993 December 31 1993 written by and published by . This book was released on 1993 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt: Customarily, coal and lignite have not been considered viable reburning fuels for a number of reasons. NO reduction through homogeneous gas phase mechanisms is generally believed more important than the heterogeneous NO reduction on char; and coal devolatilization in the fuel rich environment generates only about 50% of the volatile hydrocarbon radicals than gaseous hydrocarbons under the same fuel-to-oxidant stoichiometry. In addition, the fuel nitrogen could result in additional nitrogen oxide emissions in the burnout stage. What has not been anticipated is the highly active nature of lignite char surface. First, it has been demonstrated in the literature that lignite char can be gasified by nitrogen oxide; second, the minerals in lignite char can catalyze the CO + NO and gasification reaction; and third, lignite char has a highly porous structure which is desirable for gas/solid reactions. The unique NO activity on char surface is expected to benefit the utilities which are involved in coal combustion and have to meet the stringent Clean Air Act Amendments of 1990. This program is aimed at a better understanding of the chemical and physical mechanisms involved in the reburning with chars. Char gasification rates will be measured with and without the presence of CO. Further, the rate of the char catalyzed CO + NO reaction will also be measured. Experiments have been conducted with a flow reactor which simulates the reburning stage. One bituminous coal and two lignites, one from North Dakota and the other from Mississippi, are used in these tasks. A unique component of this program is the use of the fractal concept in the estimations of these gas/solid reaction rates. The proposed program is designed to investigate the relative importance of these two reactions (char gasification and ash catalyzed CO + NO reactions) under reburning conditions.

Download or read book Superior Catalysts for Selective Catalytic Reduction of Nitric Oxide Quarterly Technical Progress Report April 1 1995 June 30 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 Investigation of Mineral Transformations and Ash Deposition During Staged Combustion Quarterly Technical Progress Report April 1 1995 June 30 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 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.

Download or read book The Role of Pore Structure on Char Reactivity Quarterly Progress Report January 1995 March 1995 written by and published by . This book was released on 1995 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to examine the role of pore structure, studies will be conducted on coal chars in the electrodynamic balance. Larger particles will also be examined using a fluidized bed to examine diffusion control reactions, and soots will also be investigated to examine the role of meso- and micro-pores without macro-pore interference. These studies will allow a full range of particle sizes and temperatures to be investigated and eventually modelled.

Download or read book Government Reports Annual Index written by and published by . This book was released on 1995 with total page 1686 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sections 1-2. Keyword Index.--Section 3. Personal author index.--Section 4. Corporate author index.-- Section 5. Contract/grant number index, NTIS order/report number index 1-E.--Section 6. NTIS order/report number index F-Z.

Download or read book Superacid Catalysis of Light Hydrocarbon Conversion DOE PETC Seventh Quarterly Progress Report April 1 1995 July 31 1995 written by and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: