Download or read book Predictions of NOx Emissions in Pulverized Coal Combustion written by Niko Hachenberg and published by . This book was released on 2014 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this research work was to develop a transferable mathematically simple model which gives the possibility to make fast and easy predictions regarding the NOx emission behavior of a broad-spectrum of coals within a certain combustion environment. In this context, this thesis is a further step of a common ongoing investigation focused on predicting NOx emissions from self-sustaining, pulverized coal combustion in dry bottom firing systems. A comprehensive literature research focused on already published NOx prediction approaches from scientific publications based on fundamental quantitative relationships or empirical algorithms and statistical relationships was also carried out in this context. This research concentrated on three specific areas which were found to constitute a major gap in the knowledge of NOx formation in industrial full-scale applications: the fuel properties; the dependence of furnace geometry factors; and the specific operating conditions. The developed model shows a strong statistical significance with a coefficient of determination of 0.9876 and a standard error of 28 mg / m3 STPdry at 6 % O2 based on 142 observations coming from 28 utility boilers. Direct comparisons between model history and observations reported by other researchers have also shown very good conformities. For that background, this thesis form a good basis for identifying individual factors which contributes to system related NOx emissions in order to investigate how variations in the process parameters affect the emission level. Perhaps, as contribution to the understanding of NOx formation during coal combustion what is still an imperfectly understood phenomenon, or as basis for possible process optimization which might find application on pulverized coal-fired boilers to make the world a little bit more green.
Download or read book Framework for a Robust Predictor of NOx Emissions from Pulverised Coal Combustion III Existing and Proposed NOx Prediction Methods for PF Plant written by R.D.C. Smith and published by . This book was released on 1997 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Framework for a Robust Predictor of NOx Emissions from Pulverised Coal Combustion written by R. D. C. Smith and published by . This book was released on 1997 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 23 European Symposium on Computer Aided Process Engineering written by Achim Wechsung and published by Elsevier Inc. Chapters. This book was released on 2013-06-10 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: A dynamic model of a coal fired boiler is proposed to predict the formation of NOx during plant operation. Since evaluation of the model at hand should only take few minutes, computationally expensive CFD simulations are not feasible. Instead, it is proposed to represent the boiler as a network of ideal reactors. Gas phase reactions are modeled using a detailed kinetic mechanism; additional consideration is necessary for the heterogeneous reactions on char particles. In the reported preliminary case studies, radiative heat transfer is not considered.
Download or read book Fundamentals of the Physical Chemistry of Pulverized Coal Combustion written by L. Lahaye and published by Springer Science & Business Media. This book was released on 1987-08-31 with total page 526 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of coal for the production of energy is certainly not a new area of research. Many research works were carried out to improve the efficiency of industrial and domestic facilities. In the sixties, however, because of the availability and low cost of petroleum, coal consumption decreased and the research effort in this area was minimum. Meanwhile, the situation has totally changed. Considering the reserves of oil and the instability ofregions where they are located, it is becoming absolutely necessary to develop other sources of energy.The major alternative to oil appears to be coal, at least for the near future. Indeed, the reserves known today represent several centuries of energy consumption.!t is therefore becoming urgent to develop efficient and non polluting technologies to produce energy from coal. The main possibilities are : · liquefaction · gasification · directed combustion. Research and development efforts on liquefaction have been considerably reduced because of high cost of technologies involved and poor prospects for the next two decades. Research works on gasification are progressing; it is a promising approach. However, direct combustion either in pulverized coal furnaces or in fluidized beds is the more promising way of expanding rapidly the utilization of coal. These techniques are already used in some facilities but many environmental problems remain, slowing down their development.
Download or read book Emissions Reduction written by A. Tomita and published by Elsevier. This book was released on 2001-12-18 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past decade the topic of emissions reduction and control has remained an important area of research due to the enforcement of various Government policies in an attempt to minimize the impact on the environment. One area in which a great deal of research has been conducted to address this policy is NOx/SOx suppression. However, despite the progress that has been made over this time period, further research into the most effective method of reducing NOx/SOx emissions is still urgently required. In developed countries, a more stringent requirement in the level of emissions (such as is NOx/SOx component of less than 10ppm) will be enforced in the near future. Developing countries will also need a new technology that is effective and that is suited to each countries needs. Additional research and development efforts are thus necessary to meet such requirements. This compendium contains a collection of key papers themed around NOx/SOx emissions from combustion of hydrocarbon resources and the attempts to secure an efficient and effective method for reducing these emissions. These key papers are taken from the journals Fuel, Fuel Processing Technology and Progress in Energy and Combustion Science.
Download or read book Modeling the Nox Emissions in a Low Nox Burner While Fired with Pulverized Coal and Dairy Biomass Blends written by Hari Krishna Uggini and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: New regulations like the Clean Air Interstate Rule (CAIR) will pose greater challenges for Coal fired power plants with regards to pollution reduction. These new regulations plan to impose stricter limits on NOx reduction. The current regulations by themselves already require cleanup technology; newer regulations will require development of new and economical technologies. Using a blend of traditional fuels and biomass is a promising technology to reduce NOX emissions. Experiments conducted previously at the Coal and Biomass energy lab at Texas A & M reported that dairy biomass can be an effective Reburn fuel with NOX reduction of up to 95 percent; however little work has been done to model such a process with Feedlot Biomass as a blend with the main burner fuel. The present work concerns with development of a zero dimensional for a low NOX burner (LNB) model in order to predict NOx emissions while firing a blend of Coal and dairy biomass. Two models were developed. Model I assumes that the main burner fuel is completely oxidized to CO, CO2,H20 and fuel bound nitrogen is released as HCN, NH3, N2; these partially burnt product mixes with tertiary air, undergoes chemical reactions specified by kinetics and burns to complete combustion. Model II assumes that the main burner solid fuel along with primary and secondary air mixes gradually with recirculated gases, burn partially and the products from the main burner include partially burnt solid particles and fuel bound nitrogen partially converted to N2, HCN and NH3. These products mix gradually with tertiary air, undergo further oxidation-reduction reactions in order to complete the combustion. The results are based on model I. Results from the model were compared with experimental findings to validate it. Results from the model recommend the following conditions for optimal reduction of NOx: Equivalence Ratio should be above 0.95; mixing time should be below 100ms. Based on Model I, results indicate that increasing percentage of dairy biomass in the blend increases the NOx formation due to the assumption that fuel N compounds (HCN, NH3) do not undergo oxidation in the main burner zone. Thus it is suggested that model II must be adopted in the future work.
Download or read book Feasibility and NOx Reduction Potential of Flameless Oxidation in Pulverised Coal Combustion written by Dragisa Ristic and published by Cuvillier Verlag. This book was released on 2012-10-30 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the 1990, the flameless oxidation technology has been successfully proven as low-NOx combustion technology for gaseous hydrocarbon fuels, and the recent application of this technology to solid fuels such as pulverised coal has also become an area of interest. The objective of this thesis is to evaluate the feasibility and the potential of the flameless oxidation technology in the pulverised coal combustion. Firstly, the experimental studies on pulverised coal flameless oxidation process are conducted at a bench-scale test facility (5 to 10 kWth). In the next step, a suitable burner design in a pilot scale of approximately 300 kWth is developed, built up and experimentally studied. Detailed exhaust gas and inflame measurements of the temperature and, main species are carried out in order to address the specific aspects of pulverised coal flameless oxidation. Furthermore, to indicate the relevant NOx reduction mechanisms in the pulverised coal flameless oxidation process. In contrast to the conventional pulverised coal combustion, which has luminous and aerodynamically stabilised flames, the flameless oxidation combustion process has been achieved without a clearly visible flame. In the pulverised coal flameless oxidation mode, intensive internal recirculation is enhanced by a high injection velocity of the combustion air, and thus dilutes the combustion zone and heats up the coal particles in the primary pyrolysis zone. Once the coal particles are rapidly heated up, the processes of pyrolysis and volatile matter release are facilitated. Consequently, local reducing zone is formed, devolatilisation is enhanced, ignition delay is suppressed, combustion stability is improved and NOx emissions are reduced remarkably. A high internal recirculation of the oxygen-lean hot combustion products into the primary pyrolysis zone promotes an early devolatilisation and a decrease in ignition delay, which are two important factors for NOx reduction processes. Hence, a valuable potential of pulverised coal flameless oxidation is in the improved homogeneous gas phase kinetics and an enhanced homogeneous NO reburning mechanism. Besides NO reduction in the homogeneous gas phase, it is indicated that the NO reduction on the char surface in the heterogeneous and homogeneous gas phases is important as well, i.e. char NO reduction reaction and catalytic reduction of NO by CO on the char surface, in the pulverised coal flameless oxidation. As an overall conclusion, the PC FLOXTM (Pulverised Coal Flameless Oxidation) burner technology generally is evaluated as a perspective technology to provide low cost low NOx burners for utility boilers. Moreover, the PC FLOXTM burner technology offers the possibility of a lower cost alternative to the current approach of utilising SCR to enable power plants to meet current and future specific requirements on NOx emissions. However, despite all the advantages of this technology, it has been recognised that there are considerable technical challenges to the implementation of PC FLOXTM burners in utility boilers. High pressure loss in the main combustion air supply, boiler and burner design, arrangement of burners, start-up and shutdown procedures, etc. all require significant further work in order to bring the PC FLOXTM burner technology closer to the utility scale boilers.
Download or read book NOx Modelling and Prediction written by Ruksana Moreea-Taha and published by . This book was released on 2000 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamentals of the Physical Chemistry of Pulverized Coal Combustion written by L Lahaye and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 505 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of coal for the production of energy is certainly not a new area of research. Many research works were carried out to improve the efficiency of industrial and domestic facilities. In the sixties, however, because of the availability and low cost of petroleum, coal consumption decreased and the research effort in this area was minimum. Meanwhile, the situation has totally changed. Considering the reserves of oil and the instability ofregions where they are located, it is becoming absolutely necessary to develop other sources of energy.The major alternative to oil appears to be coal, at least for the near future. Indeed, the reserves known today represent several centuries of energy consumption.!t is therefore becoming urgent to develop efficient and non polluting technologies to produce energy from coal. The main possibilities are : · liquefaction · gasification · directed combustion. Research and development efforts on liquefaction have been considerably reduced because of high cost of technologies involved and poor prospects for the next two decades. Research works on gasification are progressing; it is a promising approach. However, direct combustion either in pulverized coal furnaces or in fluidized beds is the more promising way of expanding rapidly the utilization of coal. These techniques are already used in some facilities but many environmental problems remain, slowing down their development.
Download or read book ASME 70 WA APC 3 written by C. R. McCann and published by . This book was released on 1970 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Enhanced Combustion Low NOx Pulverized Coal Burner written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: For more than two decades, Alstom Power Inc. (Alstom) has developed a range of low cost, infurnace technologies for NOx emissions control for the domestic U.S. pulverized coal fired boiler market. This includes Alstom's internally developed TFS 2000{trademark} firing system, and various enhancements to it developed in concert with the U.S. Department of Energy. As of the date of this report, more than 270 units representing approximately 80,000 MWe of domestic coal fired capacity have been retrofit with Alstom low NOx technology. Best of class emissions range from 0.18 lb/MMBtu for bituminous coal to 0.10 lb/MMBtu for subbituminous coal, with typical levels at 0.24 lb/MMBtu and 0.13 lb/MMBtu, respectively. Despite these gains, NOx emissions limits in the U.S. continue to ratchet down for new and existing boiler equipment. On March 10, 2005, the Environmental Protection Agency (EPA) announced the Clean Air Interstate Rule (CAIR). CAIR requires 25 Eastern states to reduce NOx emissions from the power generation sector by 1.7 million tons in 2009 and 2.0 million tons by 2015. Low cost solutions to meet such regulations, and in particular those that can avoid the need for a costly selective catalytic reduction system (SCR), provide a strong incentive to continue to improve low NOx firing system technology to meet current and anticipated NOx control regulations. The overall objective of the work is to develop an enhanced combustion, low NOx pulverized coal burner, which, when integrated with Alstom's state-of-the-art, globally air staged low NOx firing systems will provide a means to achieve: Less than 0.15 lb/MMBtu NOx emissions when firing a high volatile Eastern or Western bituminous coal, Less than 0.10 lb/MMBtu NOx emissions when firing a subbituminous coal, NOx reduction costs at least 25% lower than the costs of an SCR, Validation of the NOx control technology developed through large (15 MWt) pilot scale demonstration, and Documentation required for economic evaluation and commercial application. During the project performance period, Alstom performed computational fluid dynamics (CFD) modeling and large pilot scale combustion testing in its Industrial Scale Burner Facility (ISBF) at its U.S. Power Plant Laboratories facility in Windsor, Connecticut in support of these objectives. The NOx reduction approach was to optimize near-field combustion to ensure that minimum NOx emissions are achieved with minimal impact on unburned carbon in ash, slagging and fouling, corrosion, and flame stability/turn-down. Several iterations of CFD and combustion testing on a Midwest coal led to an optimized design, which was extensively combustion tested on a range of coals. The data from these tests were then used to validate system costs and benefits versus SCR. Three coals were evaluated during the bench-scale and large pilot-scale testing tasks. The three coals ranged from a very reactive subbituminous coal to a moderately reactive Western bituminous coal to a much less reactive Midwest bituminous coal. Bench-scale testing was comprised of standard ASTM properties evaluation, plus more detailed characterization of fuel properties through drop tube furnace testing and thermogravimetric analysis. Bench-scale characterization of the three test coals showed that both NOx emissions and combustion performance are a strong function of coal properties. The more reactive coals evolved more of their fuel bound nitrogen in the substoichiometric main burner zone than less reactive coal, resulting in the potential for lower NOx emissions. From a combustion point of view, the more reactive coals also showed lower carbon in ash and CO values than the less reactive coal at any given main burner zone stoichiometry. According to bench-scale results, the subbituminous coal was found to be the most amenable to both low NOx, and acceptably low combustibles in the flue gas, in an air staged low NOx system. The Midwest bituminous coal, by contrast, was predicted to be the most challenging of the three coals, with the Western bituminous coal predicted to behave in-between the subbituminous coal and the Midwest bituminous coal. CFD modeling was used to gain insight into the mechanisms governing nozzle tip performance with respect to NOx emissions. The CFD simulations were run as steady state, turbulent, non-reacting flow with heat transfer and focused on predicting the near field mixing and particle dispersion rates. CFD results were used to refine the proposed tip concepts before they were built, as well as to help identify and evaluate possible improvements to the tips for subsequent test weeks.
Download or read book Combustion of Pulverised Coal in a Mixture of Oxygen and Recycled Flue Gas written by Dobrin Toporov and published by Elsevier. This book was released on 2014-05-30 with total page 199 pages. Available in PDF, EPUB and Kindle. Book excerpt: Combustion of Pulverised Coal in a Mixture of Oxygen and Recycled Flue Gas focuses on a niche technology, combustion of coal in an oxygen rich environment, which is one approach to obtaining 'clean coal,' by making it easier to capture carbon that is released in the combustion process. Toporov's book breaks ground on covering the key fundamentals of oxycoal technologies, which have not yet been covered in this depth. Combustion of Pulverised Coal in a Mixture of Oxygen and Recycled Flue Gas summarizes the main results from a pioneering work on experimental and numerical investigations of oxyfuel technologies. It provides the theoretical background of the process, the problems to be faced, and the technical solutions that were achieved during these investigations. - Summarizes results from investigations of oxyfuel technologies performed at Aachen University, Germany - Provides theoretical background, as well as the primary problems of these technologies and how they can be solved
Download or read book Combustion Optimization Based on Computational Intelligence written by Hao Zhou and published by Springer. This book was released on 2018-02-02 with total page 291 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the latest findings on the subject of combustion optimization based on computational intelligence. It covers a broad range of topics, including the modeling of coal combustion characteristics based on artificial neural networks and support vector machines. It also describes the optimization of combustion parameters using genetic algorithms or ant colony algorithms, an online coal optimization system, etc. Accordingly, the book offers a unique guide for researchers in the areas of combustion optimization, NOx emission control, energy and power engineering, and chemical engineering.
Download or read book Single and Two phase Reacting Flow Predictions modeling of Nonequilibrium Effects Turbulent Particle Dispersion and Nitrogen Oxide Formation in Pulverized Coal Combustion written by Dong Soon Jang and published by . This book was released on 1987 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract.
