CORDIS provides links to public deliverables and publications of HORIZON projects.
Links to deliverables and publications from FP7 projects, as well as links to some specific result types such as dataset and software, are dynamically retrieved from OpenAIRE .
Exploitable results
The primary aim of the EURONITE project was to reduce the size of combustion chamber for reduced heat losses, energy consumption and CO2 production as well as keeping the NOx emissions low through combustion intensification and aerodynamics optimisation. To achieve this, an eight partner consortium from five European Countries was formed, consisting of four academic partners, two industrial partners, one research establishment and a small and medium size enterprise. The approach to the project has been fundamental mathematical modelling and experimental studies, pilot-scale data collection and model validation, and finally extrapolation of the results for industrial applications. The results obtained are very promising in that detailed mathematical models for high temperatures (oxygen-enrichment) and air vitiation conditions have been constructed and laboratory and pilot-scale data related to NOx under oxygen-enrichment and flue gas re-circulation have been compiled. Finally, the design of a prototype FLOX burner has been accomplished which will provide a solid foundation for the design of an industrial energy efficient and low-NOx glass furnace.
The main findings of the EURONITE project are summarized below:
1. For improved turbulence modelling, an extended flamelet model was developed as a new approach for improved CFD predictions of detailed turbulent combustion in glass-melting furnaces. The features of new model include the capabilities to account for the non-equilibrium chemistry effects in turbulent flames (including NOx and soot formation mechanisms) and the effect of re-circulation of flue gases in 3-D furnace domain as well as the radiative and convective heat loss. New detailed chemical kinetic mechanism for oxidation of hydrocarbons up to C4, simultaneously including the prompt and thermal NOx formation mechanisms (in total 59 species, 333 reactions), has been elaborated.
2. The proposed model has been implemented into CFD code FURNACE v.4.0 (TU Delft).
3. Validation of computational results on experimental data obtained from the partners has demonstrated the ability of new flamelet model to predict heat transfer and species of major interest (O2, CO2, CO, OH, soot, etc.) with satisfactory accuracy providing correct qualitative trends. The comparison has also shown that NOx levels were under predicted. However, the simulations correctly indicated the trend of decreasing NOx emission with changing the furnace working regime (from Heye standard burner to WS FLOX? burner).
4. Detailed data archive in a 0.5MW down-fired furnace was completed subsequent to the incorporation of facilities for the re-circulation of the flue gases and injection of the oxygen. In addition, a compact flame was also achieved with the construction of a dual-fuel burner, namely the annular primary fuel and central primary fuel injection facilities (APF and CPF).
5. This was followed by a detailed flame stability analysis (over 70 flames) in order to characterise the effect of operational variation on the combustion and NOx emissions. During the second year of the project, data related to another fuel, coal, were analysed for the compact flame producing burner configuration, the APF burner concept. The results are similar to the natural gas-fired case in that the mode of oxygen mixing is the most important factor the NOx formation and emission point of view. The combustion pattern, as determine from the CO, CO2 and O2, is quite similar in terms of flame shape and its length but NOx formation increases when the oxygen is injected from the central tube as compared with the injection of the same amount from the secondary air. This is due to the fact that slower oxygen and fuel mixing takes place when oxygen is injected with the secondary air. The effect of flue gas re-circulation is, again, expected to be the same, as was observed for the natural gas flames, in order to reduce the peak flame temperatures and consequently the resulting NOx emissions. This effect was further verified using the CPF mode where only 20% increase was observed for two CPF flames (under identical conditions of APF) as compared with the base case flame.
6. From the convective and radiative experimental and modelling in a bench-scale study, using the WS FLOX(beta) burner it was found that the convective share compared to the radiative increases by using FLOX technology, but it is not higher than 5% of the heat transfer so that it can be neglected. It can be concluded that further parametric studies of both geometrical and physical conditions have the potential for improving furnace efficiency and reducing pollutant emissions. The conversion to real glass melting furnaces is recommendable.
7. Large-scale tests were conducted for two conventional burners (Heye standard burner and Heye staged burner) and compared with new burner concepts (WS FLOX burner and GWI staged burner). In addition, an advanced oxy-fuel burner (MG oxy-fuel burner) has been tested and compared with the air-fuel burners. For glass furnaces, the flame length and the location of the maximum heat transfer within the flame have an important influence on glass quality because they influence the flow distribution within the glass melt. In addition, the total heat transfer and the radiation depending on the wavelength have an important influence. The results clearly indicate that with the new burner technology it is possible to reduce the NOx emission drastically so that the 500 mg/m(3) NOx limit could be achieved at glass melting furnaces. With the new burners, it is possible to achieve the same size of flames as compared with conventional burners. With the OH measurement technique, it was possible to locate the zones with high combustion intensity within the reaction zone for the different burners. The results that have been obtained with different heat flux measurement techniques indicate, that the heat flux of the new burners are in the same range like the results for the conventional burner. From these results, one can conclude that the reduced temperature in the reaction zones of the new low NOx burners have no negative influence on heat transfer. This could be explained by the fact that the high temperature region in a reaction zone of a flame has only a small volume compared with the whole flame and the whole furnace volume. On the other hand, these high temperature regions lead to high thermal NOx formation if the temperature is high. Therefore, it is important to avoid these high temperatures in order to achieve low NOx emissions.
8. The developed industrial-scale burner showed very promising results, especially regarding NOx-emissions, while still being of simple design. It is planned to install a prototype in a glass tank to verify the performance under real technical conditions.
9. Finally, it was observed that the combined preheating and oxygen enriched combustion increased the overall fuel savings substantially at relatively low levels of oxygen enrichment, while at high levels of oxygen enrichment, little additional savings can be obtained.
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