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Speth K.,TU Munich | Murer M.,Martin GmbH fur Umwelt und Energietechnik | Spliethoff H.,TU Munich | Spliethoff H.,Bavarian Center for Applied Energy Research
Energy and Fuels | Year: 2016

The formation of the nitrogen species HCN, NH3 (N-intermediates), and NO out of fuel-bound nitrogen has a major influence on NO chemistry. Experiments have been carried out on an entrained flow reactor with pulverized wood as fuel. Staged combustion establishes a fuel-rich primary zone, where both N-intermediates and NO exist. The introduction of NRP as the ratio of the N-intermediates to NO offers a parameter that describes the nitrogen distribution in the primary zone, whereas TFN describes the overall amount of nitrogen. Air staging is an effective method for NOx reduction; the main controlling parameter is the primary air ratio, which defines both NRP and TFN. In fuel-rich conditions, NRP exceeds 1; with increased oxygen availability and temperature, the N-intermediates are depleted and NO is formed (NRP < 1). Thus, the NRP can be increased by adding NH3. Conventional SNCR is strongly temperature-dependent; hence, with increased temperatures, the best operation point shifts to lower air ratios. A combination of air staging and ammonia injection directly in the primary zone furthers NOx reduction, as long as it is realized in almost stoichiometric conditions. Since the reduction efficiency increases at high temperatures, the technology is called selective high temperature reduction. © 2016 American Chemical Society. Source

Bourtsalas A.,Imperial College London | Bourtsalas A.,Columbia University | Vandeperre L.,Imperial College London | Grimes S.,Imperial College London | And 3 more authors.
Waste Management and Research | Year: 2015

The fine dust of incinerator bottom ash generated from dry discharge systems can be transformed into an inert material suitable for the production of hard, dense ceramics. Processing involves the addition of glass, ball milling and calcining to remove volatile components from the incinerator bottom ash. This transforms the major crystalline phases present in fine incinerator bottom ash dust from quartz (SiO2), calcite (CaCO3), gehlenite (Ca2Al2SiO7) and hematite (Fe2O3), to the pyroxene group minerals diopside (CaMgSi2O6), clinoenstatite (MgSi2O6), wollastonite (CaSiO3) together with some albite (NaAlSi3O8) and andradite (Ca3Fe2Si3O12). Processed powders show minimal leaching and can be pressed and sintered to form dense (>2.5 g cm-3), hard ceramics that exhibit low firing shrinkage (<7%) and zero water absorption. The research demonstrates the potential to beneficially up-cycle the fine incinerator bottom ash dust from dry discharge technology into a raw material suitable for the production of ceramic tiles that have potential for use in a range of industrial applications. © The Author(s) 2015. Source

Koralewska R.,Martin GmbH fur Umwelt und Energietechnik
19th Annual North American Waste-to-Energy Conference, NAWTEC19 | Year: 2011

During combustion, most of the waste's nitrogen content is transferred to the flue gases as nitrogen oxide, NO x. The EU Waste Incineration Directive defines a maximum emission limit value for NOx of 200 mg/Nm 3 as a daily average value referred to 11% O 2. Based on National Emission Ceilings (NEC) defined by the Gothenburg Protocol, it can be expected that the limit values for NO x in the EU will become even more stringent. In some European countries (e.g. The Netherlands, Austria, Switzerland) a lower emission limit has already been introduced. Selective Catalytic Reduction (SCR) technologies are used in many cases to achieve the above-mentioned NO x limits. However, there are drawbacks to SCR systems such as high investment cost. Operation cost is also quite high due to the energy consumption necessary for the reheating of the flue gas as well as the increased pressure loss. Innovative technologies are therefore required to make it possible to reconcile both requirements: reduced emissions and increased energy efficiency. Selective Non-Catalytic Reduction (SNCR) systems are based on the selective reaction of ammonia or urea injected into the upper furnace. In many cases SNCR technologies are limited by the ammonia slip which increases in case of more stringent NO x requirements. According to the relevant BREF document, an ammonia slip limit of 10 mg/Nm 3 is generally required at the stack. In order to achieve reduced NO x values, it is necessary to implement measures to reduce ammonia slip, by means of either a wet scrubber or a High-dust catalytic converter. EfW plants in Mainz (Germany) and Brescia (Italy) are examples of operational plants combining SNCR with such a catalytic converter type. In addition R&D activities are carried out on the development of simplified reaction mechanisms to be implemented in Computational Fluid Dynamics (CFD) codes. With these tools it will be possible to describe the interaction between turbulent mixing, radiation and chemical reaction rates. Another option to achieve low NO x values (below 100 mg/Nm 3) is the reduction of NO x by so-called primary measures, e.g. the Very Low NO x process (VLN), which has been developed by MARTIN jointly with its cooperation partners. The VLN process is based on a grate-based combustion system. The "VLN gas" is drawn off at the rear end of the grate and is reintroduced into the upper furnace in the vicinity of the SNCR injection positions. NO x will be reduced significantly, ensuring low NO x emission values at the stack as required, at low values for ammonia slip. The new EfW plant in Honolulu (USA) will be equipped with the VLN process. In Coburg (Germany), the VLN process will be retrofitted in an existing installation. This paper documents the potential and the limitations of different measures for NO x reduction as well as examples of recent innovative EfW plants in Europe using MARTIN technologies successfully. © 2011 by ASME. Source

Koralewska R.,Martin GmbH fur Umwelt und Energietechnik
18th Annual North American Waste-to-Energy Conference, NAWTEC18 | Year: 2010

Thermal treatment of waste using grate-based systems has gained world-wide acceptance as the preferred method for sustainable treatment of waste. It is therefore necessary to develop innovative processes with safe process engineering technology that guarantee the treatment of waste in accordance with ecological and economic constraints in addition to complying with legal requirements. This paper documents successful use of industrial-scale R&D using MARTIN technology in providing solutions for optimizing grate-based Energy-from-Waste technologies in terms of protection of climate and resources, reduction of environmental impacts as well as political, regulatory and market aspects. © 2010 by ASME. Source

Koralewska R.,Martin GmbH fur Umwelt und Energietechnik
20th Annual North American Waste-to-Energy Conference, NAWTEC 2012 | Year: 2012

Energy-from-Waste plants using grate-based systems have gained world-wide acceptance as the preferred method for the sustainable treatment of waste. Key factors are not only the reduction of waste volume and mass and the destruction or separation of pollutants but also the efficient production and use of energy (electricity, district heating/ cooling, process steam), compliant disposal and the recovery of resources from combustion residues (e.g. metals, rare earths). International requirements relating to energy efficiency and materials recovery by means of thermo-recycling in Energy-from-Waste plants call for the continuing development and optimization of existing technologies and concepts. The technologies and processes for the recovery of reusable materials from dry-discharged bottom ash and from filter ash point to the key role that Energy-from-Waste plants are able to play in the efficient conservation of resources. It is primarily thermal treatment with dry discharge and subsequent processing of the bottom ash fractions that enables Energy-from-Waste plants to justify their status as universal recyclers. In addition to recovery of the energy inherent in the waste, the treatment of drydischarged bottom ash is an important contribution to compliance with raw material and climate policies and to the promotion of closing the material cycle in general. Furthermore, dry bottom ash discharge represents a further step towards waste-free operation and "after-care-free" landfills. This paper documents the potential of Energy-from-Waste plants for the recovery of resources and provides examples of recent developments and large-scale implementations of innovative recovery technologies in Europe. Copyright © 2012 by ASME. Source

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