Download or read book COMPUTATIONAL MODELING AND EXPERIMENTAL STUDIES ON NOx REDUCTION UNDER PULVERIZED COAL COMBUSTION CONDITIONS written by and published by . This book was released on 1998 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, both computer simulation and experimental studies were conducted to investigate several strategies for NO(subscript x) reduction under pulverized coal combustion conditions with an aim to meet the stringent environmental standards for NO(subscript x) control. Both computer predictions and reburning experiments yielded favorable results in terms of NO(subscript x) control by reburning with a combination of methane and acetylene as well as non-selective catalytic reduction of NO(subscript x) with ammonia following reburning with methane. The greatest reduction was achieved at the reburning stoichiometric ratio of 0.9; the reduction was very significant, as clearly shown in Chapters III and V. Both the experimental and computational results favored mixing gases: methane and acetylene (90% and 10% respectively) and methane and ammonia (98% and 2%) in order to get optimum reduction levels which can not be achieved by individual gases at any amounts. Also, the above gaseous compositions as reburning fuels seemed to have a larger window of stoichiometric ratio (SR2 0.9) as opposed to just methane (SR2=0.9) so as to reduce and keep NO(subscript x) at low ppm levels. From the various computational runs, it has been observed that although there are several pathways that contribute to NO(subscript x) reduction, the key pathway is NO -- HCN --> NH3 --> N2 + H2. With the trends established in this work, it is possible to scale the experimental results to real time industrial applications using computational calculations.
Download or read book Computational Modeling and Experimental Studies on NO x Reduction Under Pulverized Coal Combustion Conditions written by and published by . This book was released on 1997 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: During this quarter efforts were made to conduct reburning experiments with coal. Our efforts met with partial success but there arose persistent problems with the operation of the coal feeder. This entire quarter has been the most challenging time for the research team in terms of solving the problems and carrying out the intended experiments. Discussed below are some of the results as well as challenges. We hope to overcome the problems in due time. At the writing of this report, some parts of the coal feeder are being rebuilt by MK Fabrication.
Download or read book Computational Modeling and Experimental Studies on NOx Reduction Under Pulverized Coal Combustion Conditions Technical Progress Report Fifth Quarter 1 January 1996 31 March 1996 written by and published by . This book was released on 1996 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: During this quarter, the focus was on getting the experimental facility ready for operation. Upon receiving all the pieces of equipment, the research team first spent a great deal of time in calibration of various instruments and then began assembling the pieces for the experimental work. The use of Swage-lock fittings helped in arresting the gas leaks fairly easily. The entire assembly consisted of teflon tube connections (a) from gas cylinders to the flow meters, manifold and buffer vessel, (b) from buffer vessel to the inlet of the reactor enclosed in the middle, by a furnace, (c) from the exhaust end of the reactor to the NOx analyzer via gas dryer and (d) from the analyzer to the vent. Details of the experimental setup are given in the subsequent section. Once the setup was checked for leaks and the leaks were arrested, the facility was operational. Several experiments on NO reburning with methane were undertaken. The flow rates for various gases were calculated for five reburning stoichiometric ratios and the experiments were conducted for three different reaction temperatures. The results are presented later on in this report. These results indicate favorable reduction of NO by reburning with methane, consistent with their computer projections, and hence, present a good base for investigating further on nitric oxide reburning with other fuels as well. Experiments on nitric oxide reburning with (1) a combination of methane and acetylene, and (2) a combination of methane and ammonia, will be considered in the next quarter. The computer simulation results submitted in the Second Quarterly Report indicate further reduction of NO with the addition of acetylene/ammonia to methane as reburn fuel. These results will be verified experimentally in the ensuing quarter.
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 Computational Modeling and Experimental Studies on NO sub X Reduction Under Pulverized Coal Combustion Conditions Progress Report February 1 1995 March 31 1995 written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first quarterly report of this three-year program which began on February 1, 1995. This program involves computer simulation studies to aid in planning and conducting a series of experiments that will extend our knowledge of reburning process. The objective of this work is to find nitric oxide reduction effectiveness for various reburning fuels and identify both homogeneous and heterogeneous reaction mechanisms characterizing NO reduction. To begin with, computer simulation studies have been undertaken. The updated version of CHEMKIN II (1994) package has been acquired from Sandia National Laboratories and put to use for the preliminary runs involving reburning of nitric oxide with methane. This report presents results from these computations.
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 Computational Modeling and Experimental Studies on NOsub X Reduction Under Pulverized Coal Combustion Conditions Third Quarterly Technical Progress Report 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 Computational Modeling and Experimental Studies on NO subscript X Reduction Under Pulverized Coal Combustion Conditions Third Quarterly Technical Progress Report July 1 1995 September 30 1995 written by and published by . This book was released on 1995 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental plan outlining the first year's activity was sent to Dr. Lori Gould, Project Officer/Contracting Officer's Technical Representative on April 24, 1995. An approval was received with some questions on June 15, 1995. However, with some foresight of the director of the in-house combustion group of the PETC, Dr. Ekmann, a tentative hold-off on the purchase of the equipment was requested by the project officer on June 29, 1995. Enclosed with that request were some of Dr. Ekmann's concerns. The research team spent the month of July in study of pertinent literature as well as in the preparation of the responses to Dr. Gould's comments and Dr. Ekmann's concerns. These responses included the choice of the reactor, reactor design, rate of gas heating, detailed test matrix and answers to host of other comments. Upon review of the above information submitted on July 24, 1995 by the Rust research team, the project officer called for a conference call on September 6, 1995 which involved the PI (Dr. Kumpaty), the research consultant (Mr. Subramanian), Dr. Gould and Dr. Ekmann. Dr. Ekmann insisted that further calculations be made on the rate of gas heating without taking radiation into account. Accordingly, calculations pertaining to the rate of gas heating based on convection were performed and submitted to Dr. Ekmann on September 13, 1995. This report contains the information emerged through the dialogue between the Rust College research team and the PETC represented by Dr. Gould and Dr. Ekmann during this quarter.
Download or read book Computational Modeling and Experimental Studies on NOsub X Reduction Under Pulverized Coal Combustion Conditions Progress Report Fevruary 1 1995 March 31 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 NOsub 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 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Computational Modeling and Experimental Studies on NO3 Reduction Under Pulverized Coal Combustion Conditions Progress Report February 1 1995 March 31 1995 written by and published by . This book was released on 1995 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first quarterly report of this three-year program which began on February 1, 1995. This program involves computer simulation studies to aid in planning and conducting a series of experiments that will extend our knowledge of reburning process. The objective of this work is to find nitric oxide reduction effectiveness for various reburning fuels and identify both homogeneous and heterogeneous reaction mechanisms characterizing NO reduction. To begin with, computer simulation studies have been undertaken. The updated version of CHEMKIN II (1994) package has been acquired from Sandia National Laboratories and put to use for the preliminary runs involving reburning of nitric oxide with methane. This report presents results from these computations.
Download or read book Computational Modeling and Experimental Studies on NO x Reduction Under Pulveerized Coal Combustion Conditions Quarterly Technical Progress Report July 1 September 30 1997 written by and published by . This book was released on 1997 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Several experiments were conducted during this quarter to study the NO(subscript x) reduction effectiveness of lignite coal, activated carbon and catalytic sites such as calcium sulfide and calcium carbide. While some of the coals/chemicals could be fed easily, some needed the mixing with silica gel to result in a uniform flow through the feeder. Several trial runs were performed to ensure proper feeding of the material before conducting the actual experiment to record NO(subscript x) reduction. The experimental approach has been the same as presented in the past two quarterly reports with the coal reburning experiments. Partial reduction is achieved through methane addition for SR2=0.95 conditions and then coal or the catalyst is introduced to see if there is further reduction. Presented below are the results of the experiments conducted during this quarter.
Download or read book Modeling and Simulation of SOx and NOx Reduction Processes in Pulverized Coal Furnaces written by and published by Cuvillier Verlag. This book was released on 2003-12-18 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT The current work briefly reviews the formation mechanisms and reduction approaches of the pollutants SOx and NOx in coal combustion and focuses on the simulation of the lower-cost in-furnace measures ƒ{ the dry additive process (DAP) for SOx reduction and the reburning as well as the advanced reburning (hybrid reburning/SNCR) techniques for NOx reduction. In addition, the influence of sulfur compounds on NOx formation is investigated. The major workings include: Simulation of the dry additive desulfurization process (DAP): Different models ƒ{ shrinking core model (SCM), pore model (PM) and grain model (GM) ƒ{ are implemented to describe the gas-particle reaction. Relevant processes such as the sintering of the additive, the self-retention by coal ash, the thermal equilibrium of the sulfation reaction are accounted for and modeled. A comprehensive model for the DAP with calcium based additives is subsequently established and integrated into a combustion CFD (computational fluid dynamics) code AIOLOS, in both Eulerian and Lagrangian schemes. The model is verified with experiments on a test reactor. Mechanism reduction and simulation of reburning/SNCR Processes: A method for reduction of kinetic mechanisms is introduced. A program tool is developed for automatic reduction of detailed reaction mechanisms. Reduced mechanisms for reburning and hybrid reburning/SNCR processes are developed and implemented into the CFD code. CFD-calculations with the reduced mechanisms are performed and compared with experimental measurements to comprehensively evaluate the simulation approach. It is shown that the detailed simulation is capable of modeling the complex reburning and SNCR processes with acceptable computing time and achieves reasonable results in wide parameter ranges. Study of the influence of sulfur compounds on NOx formation: The effect of SO2 on NOx formation is experimentally investigated and analysed with kinetic mechanisms. It is indicated that the presence of SO2 inhabits the NOx formation and reduce the NOx emissions in normal air-rich combustion. Under air-staging conditions, SO2 addition has no obvious influence on the final NOx emissions.
Download or read book REDUCTION OF NOx EMISSION FROM COAL COMBUSTION THROUGH OXYGEN ENRICHMENT written by University of Wyoming Research Corporation. Western Research Institute and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: BOC Process Gas Solutions and Western Research Institute (WRI) conducted a pilot-scale test program to evaluate the impact of oxygen enrichment on the emissions characteristics of pulverized coal. The combustion test facility (CTF) at WRI was used to assess the viability of the technique and determine the quantities of oxygen required for NOx reduction from coal fired boiler. In addition to the experimental work, a series of Computational Fluid Dynamics (CFD) simulations were made of the CTF under comparable conditions. A series of oxygen enrichment test was performed using the CTF. In these tests, oxygen was injected into one of the following streams: (1) the primary air (PA), (2) the secondary air (SA), and (3) the combined primary and secondary air. Emission data were collected from all tests, and compared with the corresponding data from the baseline cases. A key test parameter was the burner stoichiometry ratio. A series of CFD simulation models were devised to mimic the initial experiments in which secondary air was enriched with oxygen. The results from these models were compared against the experimental data. Experimental evidence indicated that oxygen enrichment does appear to be able to reduce NOx levels from coal combustion, especially when operated at low over fire air (OFA) levels. The reductions observed however are significantly smaller than that reported by others (7-8% vs. 25-50%), questioning the economic viability of the technique. This technique may find favor with fuels that are difficult to burn or stabilize at high OFA and produce excessive LOI. While CFD simulation appears to predict NO amounts in the correct order of magnitude and the correct trend with staging, it is sensitive to thermal conditions and an accurate thermal prediction is essential. Furthermore, without development, Fluent's fuel-NO model cannot account for a solution sensitive fuel-N distribution between volatiles and char and thus cannot predict the trends seen in the experiment.
Download or read book MINIMIZATION OF NO EMISSIONS FROM MULTI BURNER COAL FIRED BOILERS written by and published by . This book was released on 2002 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: The focus of this program is to provide insight into the formation and minimization of NO(subscript x) in multi-burner arrays, such as those that would be found in a typical utility boiler. Most detailed studies are performed in single-burner test facilities, and may not capture significant burner-to-burner interactions that could influence NO(subscript x) emissions. Thus, investigations of such interactions were made by performing a combination of single and multiple burner experiments in a pilot-scale coal-fired test facility at the University of Utah, and by the use of computational combustion simulations to evaluate full-scale utility boilers. In addition, fundamental studies on nitrogen release from coal were performed to develop greater understanding of the physical processes that control NO formation in pulverized coal flames--particularly under low NO(subscript x) conditions. A CO/H2/O2/N2 flame was operated under fuel-rich conditions in a flat flame reactor to provide a high temperature, oxygen-free post-flame environment to study secondary reactions of coal volatiles. Effects of temperature, residence time and coal rank on nitrogen evolution and soot formation were examined. Elemental compositions of the char, tar and soot were determined by elemental analysis, gas species distributions were determined using FTIR, and the chemical structure of the tar and soot was analyzed by solid-state 13C NMR spectroscopy. A laminar flow drop tube furnace was used to study char nitrogen conversion to NO. The experimental evidence and simulation results indicated that some of the nitrogen present in the char is converted to nitric oxide after direct attack of oxygen on the particle, while another portion of the nitrogen, present in more labile functionalities, is released as HCN and further reacts in the bulk gas. The reaction of HCN with NO in the bulk gas has a strong influence on the overall conversion of char-nitrogen to nitric oxide; therefore, any model that aims to predict the conversion of char-nitrogen to nitric oxide should allow for the conversion of char-nitrogen to HCN. The extent of the HCN conversion to NO or N2 will depend on the composition of the atmosphere surrounding the particle. A pilot-scale testing campaign was carried out to evaluate the impact of multiburner firing on NO(subscript x) emissions using a three-burner vertical array. In general, the results indicated that multiburner firing yielded higher NO(subscript x) emissions than single burner firing at the same fuel rate and excess air. Mismatched burner operation, due to increases in the firing rate of the middle burner, generally demonstrated an increase in NO(subscript x) over uniform firing. Biased firing, operating the middle burner fuel rich with the upper and lower burners fuel lean, demonstrated an overall reduction in NO(subscript x) emissions; particularly when the middle burner was operated highly fuel rich. Computational modeling indicated that operating the three burner array with the center burner swirl in a direction opposite to the other two resulted in a slight reduction in NO(subscript x).
Download or read book DEVELOPMENT OF A NOVEL RADIATIVELY CONDUCTIVELY STABILIZED BURNER FOR SIGNIFICANT REDUCTION OF NOx EMISSIONS AND FOR ADVANCING THE MODELING AND UNDERSTANDING OF PULVERIZED COAL COMBUSTION AND EMISSIONS written by Noam Lior and published by . This book was released on 2003 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary objective of the proposed study was the study and analysis of, and design recommendations for, a novel radiatively-conductively stabilized combustion (RCSC) process for pulverized coal, which, based on our prior studies with both fluid fuels and pulverized coal, holds a high promise to reduce NO{sub x} production significantly. We have primarily engaged in continuing and improving our process modeling and analysis, obtained a large amount of quantitative information about the effects of the major parameters on NO{sub x} production, conducted an extensive exergy analysis of the process, evaluated the practicalities of employing the Radiatively-Conductively Stabilized Combustor (RCSC) to large power and heat plants, and improved the experimental facility. Prior experimental work has proven the feasibility of the combustor, but slagging during coal combustion was observed and should be dealt with. The primary outcomes and conclusions from the study are: (1) we developed a model and computer program that represents the pulverized coal combustion in the RCSC, (2) the model predicts that NO{sub x} emissions can be reduced by a number of methods, detailed in the report. (3) the exergy analysis points out at least a couple of possible ways to improve the exergetic efficiency in this combustor: increasing the effectiveness of thermal feedback, and adjusting the combustor mixture exit location, (4) because of the low coal flow rates necessitated in this study to obtain complete combustion in the burner, the size of a burner operating under the considered conditions would have to be up to an order of magnitude, larger than comparable commercial burners, but different flow configurations of the RCSC can yield higher feed rates and smaller dimensions, and should be investigated. Related to this contract, eleven papers were published in journals and conference proceedings, and ten invited presentations were given at university and research institutions, as well as at the Gordon Conference on Modern Development in Thermodynamics. The results obtained are very encouraging for the development of the RCSC as a commercial burner for significant reduction of NO{sub x} emissions, and highly warrants further study and development.
