Coal as a Reburn Fuel for NOx Reduction

Experiments were conducted on a 200 kW downward-fired, pilot-scale furnace where residence times and temperatures are comparable to practical units. Nine bituminous coals were used as reburning fuels to investigate various aspects of the reburning process, including key process parameters (operating stoichiometries, reburn fuel fraction, primary zone NO concentration, reburn zone residence time, temperature and mixing effects) and to assess the effectiveness of pulverised coal, including microfine, as reburn fuel. The results obtained showed that the extent of NO reduction was dependent on optimising the different process variables, and the maximum reduction achieved by doing so was 75%. The most influential variables were those coupled to the reburn zone, with the reburn zone stoichiometry being the dominant impact variable. For the range of reburn zone stoichiometries studied (0.85 - 1.03) no optimum value was obtained, however, higher reductions were generally achieved under fuel rich operations. The direct effect of varying primary zone stoichiometry on reburn performance was of minor significance, however, secondary effects such as variation in the reburn zone stoichiometry can be significant. The NO reduction process was mostly completed in the reburn zone where the optimum reburn zone residence time was around 450 ms, and only marginal gains were achieved beyond this point. The NO reduction efficiency increased with increasing primary NO concentration up to around 600 - 700 ppmv, after which the trend levels off, however, at low primary NO (<200 ppmv) it was difficult to obtain a positive NO reduction efficiency. The amount of reburn fuel or Rff required to generate the hydrocarbon radicals necessary for effective NO control was not conclusively quantified, however, from the results obtained the optimum amount of reburn fuel was in the region of 20-25% of the primary fuel input. Lower inlet gas temperature in the reburn zone generally enhanced NO reduction, however, this effect diminished under sufficiently fuel rich conditions. Furthermore, the effect of temperature in the reburn zone was dependent on residence time, with high temperature (1773 K) and long residence time (>500 ms) achieving higher reduction. Improved mixing conditions in the reburn zone enhanced reburning effectiveness, however, in fuel lean operations poorer mixing was found to improve NO reduction through local fuel rich pockets. Finer particle size distribution of the reburning coal gave rise to better NO reduction and higher burnout efficiency. The carbon burnout efficiency was around 85% - 95%, and higher gas temperature improved carbon burnout efficiency, however, under fuel rich conditions (SR2=0.85) burnout efficiency was hampered by the low oxygen concentration. Finally, the results of the multi-variate analysis undertaken to determine the importance of some of the above operational parameters on NO reduction as well as the influence of reburn coal properties such as fuel nitrogen content and volatile matter, confirmed the importance of SR2 as the dominant variable in coal reburning. The proximate volatile matter content was the most influential characteristic of the reburn fuel affecting reburn performance, while fuel nitrogen content was not as influential a parameter for the range of operating conditions and coals studied

Best Available Techniques (BAT) Reference Document for Large Combustion Plants. Industrial Emissions Directive 2010/75/EU (Integrated Pollution Prevention and Control)

The BAT Reference Document (BREF) for Large Combustion Plants is part of a series of documents presenting the results of an exchange of information between the EU Member States, the industries concerned, non-governmental organisations promoting environmental protection, and the Commission, to draw up, review, and -where necessary- update BAT reference documents as required by Article 13(1) of Directive 2010/75/EU on Industrial Emissions. This document is published by the European Commission pursuant to Article 13(6) of the Directive. This BREF for Large Combustion Plants concerns the following activities specified in Annex I to Directive 2010/75/EU: - 1.1: Combustion of fuels in installations with a total rated thermal input of 50 MW or more, only when this activity takes place in combustion plants with a total rated thermal input of 50 MW or more. - 1.4: Gasification of coal or other fuels in installations with a total rated thermal input of 20 MW or more, only when this activity is directly associated to a combustion plant. - 5.2: Disposal or recovery of waste in waste co-incineration plants for non-hazardous waste with a capacity exceeding 3 tonnes per hour or for hazardous waste with a capacity exceeding 10 tonnes per day, only when this activity takes place in combustion plants covered under 1.1 above. In particular, this document covers upstream and downstream activities directly associated with the aforementioned activities including the emission prevention and control techniques applied. The fuels considered in this document are any solid, liquid and/or gaseous combustible material including: - solid fuels (e.g. coal, lignite, peat); - biomass (as defined in Article 3(31) of Directive 2010/75/EU); - liquid fuels (e.g. heavy fuel oil and gas oil); - gaseous fuels (e.g. natural gas, hydrogen-containing gas and syngas); - industry-specific fuels (e.g. by-products from the chemical and iron and steel industries); - waste except mixed municipal waste as defined in Article 3(39) and except other waste listed in Article 42(2)(a)(ii) and (iii) of Directive 2010/75/EU. Important issues for the implementation of Directive 2010/75/EU in the Large Combustion Plants sector are the emissions to air of nitrogen oxides, sulphur dioxide, hydrogen chloride and fluoride, organic compounds, dust, and metals including mercury; emissions to water resulting especially from the use of wet abatement techniques for the removal of sulphur dioxide from the flue gases; resource efficiency and especially energy efficiency. This BREF contains 12 Chapters. Chapters 1 and 2 provide general information on the Large Combustion Plants industrial sector and on the industrial processes used within this sector. Chapter 3 provides data and general information concerning the environmental performance of installations within the sector in terms of water consumption, the generation of waste and general techniques used within this sector. It also describes in more detail the general techniques to prevent or, where this is not practicable, to reduce the environmental impact of installations in this sector that were considered in determining the BAT. Chapters 4 to 9 provide the following information given below on specific combustion processes (gasification, combustion of solid fuel, combustion of liquid fuel, combustion of gaseous fuel, multi-fuel combustion and waste co-incineration). Chapter 10 presents the BAT conclusions as defined in Article 3(12) of the Directive. Chapter 11 presents information on 'emerging techniques' as defined in Article 3(14) of the Directive. Concluding remarks and recommendations for future work are presented in Chapter 12.JRC.B.5-Circular Economy and Industrial Leadershi

The development of coal-based technologies for Department of Defense facilities. Volume 1, Technical report. Semiannual technical progress report, September 28, 1994--March 27, 1995

This program is being conducted as a cooperative agreement between the Consortium for Coal Water Mixture Technology and the U.S. Department of Energy. Activities this reporting period are summarized by phase. Phase I is nearly completed. During this reporting period, coal beneficiation/preparation studies, engineering designs and economics for retrofitting the Crane, Indiana boiler to fire coal-based fuels, and a 1,000-hour demonstration of dry, micronized coal were completed. In addition, a demonstration-scale micronized-coal water mixture (MCWM) preparation circuit was constructed and a 1,000-hour demonstration firing MCWM began. Work in Phase II focused on emissions reductions, coal beneficiation/preparation studies, and economic analyses of coal use. Emissions reductions investigations involved literature surveys of NO{sub x}, SO{sub 2}, trace metals, volatile organic compounds, and fine particulate matter capture. In addition, vendors and engineering firms were contacted to identify the appropriate emissions technologies for the installation of commercial NO{sub x} and SO{sub 2} removal systems on the demonstration boiler. Information from the literature surveys and engineering firms will be used to identify, design, and install a control system(s). Work continued on the refinement and optimization of coal grinding and MCWM preparation procedures, and on the development of advanced processes for beneficiating high ash, high sulfur coals. Work also continued on determining the basic cost estimation of boiler retrofits, and evaluating environmental, regulatory, and regional economic impacts. In addition, the feasibility of technology adoption, and the public`s perception of the benefits and costs of coal usage was studied. A coal market analysis was completed. Work in Phase III focused on coal preparation studies, emissions reductions and economic analyses of coal use

Kinetics and decomposition mechanisms of selected Nitrogen-containing species

This thesis calculates the rate of hydrogen abstraction reactions and the mechanisms of nitrogen oxides (NOx and N2O) reduction, especially those relevant to the oxidation and pyrolysis of nitrogen-rich fuels such as biomass. The dissertation firstly focuses on the interaction of hydrocarbons with the amidogen radical (NH2) and nitrogen dioxide (NO2), before analysing in detail the decomposition of ammonium nitrate (AN) both in gas and liquid media. In addition to this, the moderation of nitrous oxide (N2O) and nitrogen oxides (NOx) via their reaction with a biomass surrogate of catechol was also studied. The underlying aims of the study were to report the mechanisms and kinetic factors controlling the interaction of NH2 and NO2 radicals with a wide array of hydrocarbons, then to map out the prominent reaction pathways prevailing in the decomposition of ammonium nitrate (AN) and conversion of N2O into N2 via dissociative adsorption onto a catechol moiety. Accurate quantum-mechanical calculations probed the hydrogen abstraction reactions from small aliphatic and aromatic hydrocarbons by NH2 and NO2 radicals. Reaction and activation energies for all plausible hydrogen abstraction channels were executed with the accurate chemistry model of CBS-QB3. Reaction rate parameters were obtained based on conventional transition-state theory, accounting for a plausible contribution from tunnelling effects and treating internal rotations as hindered rotors. We established that a linear correlation existed between the strength of the C-H bonds (i.e., primary, secondary, vinylic, and benzylic) and the activation energies for H abstraction channels operated by NH2 and NO2 radicals. Moreover, the meta-hybrid Density Functional Theory (DFT) of M05-2X/6-311+G(d,p) levels elucidated viable systematic conversion routes of N2O into N2 via interaction with a catechol molecule. Two theoretical methodologies were applied to study thermal decomposition of AN in gas and liquid phases. A continuum solvation model density-polarisable continuum model (SMD-PCM) expounds the catalysing effect of water on AN thermal cracking. The solvation model systematically predicts lower activation energies when contrasted with analogous gas phase values. An important part of the thesis investigates the potential of biomass constituents for the so-called selective non-catalytic reduction of NOx into nitrogen molecules. The laboratory-scale rig offers a continuous supply of carrier and reaction gases which run through a tubular reactor coupled with FTIR spectroscopy, micro-GC and a chemiluminescence NOx analyser. The consumption of the biomass surrogate (catechol) is analysed using a triple quadruple mass spectrometer (QQQ-MS) at temperatures starting from 400 °C. Fine-tuning of experimental conditions encompasses residence time and inlet reactant mixing ratios. Above 800 °C, we report more than 80 % NOx reduction efficiency. In summary, our findings throughout the thesis present previously unreported data and new insights pertinent to the combustion chemistry of several selected N-species

Portfolio evaluation of advanced coal technology : research, development, and demonstration

Thesis (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2005.Includes bibliographical references (p. 82-84).This paper evaluates the advanced coal technology research, development and demonstration programs at the U.S. Department of Energy since the 1970s. The evaluation is conducted from a portfolio point of view and derives implications for future program design and implementation. The evaluation framework consists of four categories of criteria that assess the portfolio from strategy, diversity, partnership, and project merit points of view. The analysis of the successes and the failures of the past programs in technical, financial and managerial respects shows that these programs are reasonably successful in (1) remarkably advancing coal technologies to enable the U.S. to use coal as its major energy resource in the electricity sector when facing more stringent environmental regulation or possibly even in a greenhouse gas constrained world; (2)accumulating effective program management experience, especially involving industry in technology development from the beginning of the process to facilitate future deployment. Among these successes, a number of important features incorporated in the CCTDP are especially worth noting. These features are: (1) The program goal was well defined, which was accelerating commercialization of ACTs;(cont.) (2) All projects have been fully funded up front, which saved worries about project funding prospect and enabled performers to concentrate on project implementation; (3) The well-defined program goal and funding commitment from federal government has encouraged industrial participation. As a result, industry has shared more than 50% of the programs cost with new money; (4) The DOE share of project cost growth was capped at 25%, which has incentivized industry to be more cautious about project risk; (5) Industry was authorized to design, build, operate and own facilities, which made full use of industry expertise and resources; and (6)In general, the program created a degree of competition for a range of technologies, which has helped hedge the program risk. Notwithstanding the achievements, some problems exist in these programs, of which the major ones are: (1) imbalanced RD&D structure caused by gaps in high efficiency combustion, application of modeling and simulation in ACT R&D, under-investment in basic research and applied R&D, insufficient university and national laboratory participation in R&D programs, and weak international collaboration, especially that with China;(cont.) (2) deficiency in program management such as some political influence on project selection and operation, inefficient termination of unpromising projects, and design of inefficient programs such as the CCPI and over risky demonstration programs such as FutureGen. FutureGen, in a number of important respects such as goal defining, funding mechanism and technology option, presents a contrast to the CCTDP, the organization features of which have produced a number of successes. This elevates risk of failure of the program. Going forward, the DOE should (1) strive for more balanced program structure by enhancing R&D program and further diversifying technology options, with special attention on high efficiency combustion R&D and application of modeling and simulation; (2) draw in the successful experience of the CCTDP for efficient program design and management, especially in reconsidering program organization of FutureGen; (3) improve the processes of demonstration project selection and termination of unpromising projects in terms of minimizing political pressure on them; and (4) enhance university and national laboratory participation in R&D programs and Sino-U.S. collaboration on ACTs through joint RD&D on IGCC, USC, and pollution control devices. The collaboration may seek breakthrough with Chinese coal industry as a start.by Ayaka Naga-Jones.S.M

Selected Papers from SDEWES 2017: The 12th Conference on Sustainable Development of Energy, Water and Environment Systems

EU energy policy is more and more promoting a resilient, efficient and sustainable energy system. Several agreements have been signed in the last few months that set ambitious goals in terms of energy efficiency and emission reductions and to reduce the energy consumption in buildings. These actions are expected to fulfill the goals negotiated at the Paris Agreement in 2015. The successful development of this ambitious energy policy needs to be supported by scientific knowledge: a huge effort must be made in order to develop more efficient energy conversion technologies based both on renewables and fossil fuels. Similarly, researchers are also expected to work on the integration of conventional and novel systems, also taking into account the needs for the management of the novel energy systems in terms of energy storage and devices management. Therefore, a multi-disciplinary approach is required in order to achieve these goals. To ensure that the scientists belonging to the different disciplines are aware of the scientific progress in the other research areas, specific Conferences are periodically organized. One of the most popular conferences in this area is the Sustainable Development of Energy, Water and Environment Systems (SDEWES) Series Conference. The 12th Sustainable Development of Energy, Water and Environment Systems Conference was recently held in Dubrovnik, Croatia. The present Special Issue of Energies, specifically dedicated to the 12th SDEWES Conference, is focused on five main fields: energy policy and energy efficiency in smart energy systems, polygeneration and district heating, advanced combustion techniques and fuels, biomass and building efficiency

Advanced power assessment for Czech lignite. Task 3.6, Volume 1

The US has invested heavily in research, development, and demonstration of efficient and environmentally acceptable technologies for the use of coal. The US has the opportunity to use its leadership position to market a range of advanced coal-based technologies internationally. For example, coal mining output in the Czech Republic has been decreasing. This decrease in demand can be attributed mainly to the changing structure of the Czech economy and to environmental constraints. The continued production of energy from indigenous brown coals is a major concern for the Czech Republic. The strong desire to continue to use this resource is a challenge. The Energy and Environmental Research Center undertook two major efforts recently. One effort involved an assessment of opportunities for commercialization of US coal technologies in the Czech Republic. This report is the result of that effort. The technology assessment focused on the utilization of Czech brown coals. These coals are high in ash and sulfur, and the information presented in this report focuses on the utilization of these brown coals in an economically and environmentally friendly manner. Sections 3--5 present options for utilizing the as-mined coal, while Sections 6 and 7 present options for upgrading and generating alternative uses for the lignite. Contents include Czech Republic national energy perspectives; powering; emissions control; advanced power generation systems; assessment of lignite-upgrading technologies; and alternative markets for lignite