An efficient combustion device leading also to very low NOx emission levels

1. “The flameless oxidation mode” : An efficient combustion device leading also to very low NOx emission levels Franck DELACROIX ADEME(French Agency for energy and environment management) BAT co-ordinator EGTEI (Expert Group on Techno Economical Issues) agency leader SOx, NOx and N2O emissions of industrial processes Franck DELACROIX - ADEME

2. NOx emission reduction : Primary techniques Energy efficiency and NOx emission reduction • Optimal choice of the burner and its operating conditions • Staged combustion • Air staging • Gas staging (reburning) • Recirculation of combustion products • Internal • External • Etc... Franck DELACROIX - ADEME

3. Energy efficiency : example of regenerative burners Franck DELACROIX - ADEME

4. Energy efficiency and NOx emission reduction Possible indicative influence of air preheat on NOx emissions Franck DELACROIX - ADEME

5. Energy efficiency and NOx emission reduction • First generation of regenerative burners with very high NOx emission levels • Studies have been realized mainly in Japan, Germany and USA, • Several manufacturers have commercialised new types of burners, • Industrial demonstrations have been mainly validated in Asia, • European references at quite small scale. Principle of these new burners : the „flameless combustion mode“ Franck DELACROIX - ADEME

6. Air Process heat Combustion products III I II Gas THE FLAMELESS OXIDATION MODE : principle 1/2 • oxidising air and fuel gas injected separately with high injection speeds, • recirculations of the combustion products to the burner • high temperature of the recirculated combustion products (> 1000°C) used to initiate and maintain this mode of “combustion”. Franck DELACROIX - ADEME

7. THE FLAMELESS OXIDATION MODE : principle 2/2  combustion distributed throughout the volume of the combustion chamber, • relative homogeneity (temperature and composition) in the combustion chamber, • the flame can then no longer be seen, Explaining why experts of this field speak about :THE FLAMELESS OXIDATION OR COMBUSTION MODE Franck DELACROIX - ADEME

8. How to characterize the FLAMELESS OXIDATION MODE and explain the low NOx emission level ? Franck DELACROIX - ADEME

9. The INTERNOx project • Three years project started in October 2000 • Partners : Gaz de France, Arcelor/IRSID, Stein-Heurtey and supported by ADEME • Containing the following phases : • - Technological survey, • - Study of the heating equipments, • - Design of pre-dimensioning tools dedicated to slab furnaces, • Study at semi-industrial scale, • Validation of the simulation tools, • Preparation of a demonstration project at industrial scale. Franck DELACROIX - ADEME

10. Main goals of the study • Energy savings • Improvement of energy efficiency • Optimisation of processes • Pollution reduction • CO2 • NOx • Noise • Product quality • Process reliability Franck DELACROIX - ADEME

11. Burner characterization • WS GmbH (Germany) • North American Manufacturing Co (US) • NFK (Japan) • Etc Franck DELACROIX - ADEME

12. NOx : Influence of the main operating parameters Franck DELACROIX - ADEME

13. Main conclusions of the burner tests • Very Low NOx burners commercially available : NO <300 mg/m3(n) and η > 75% whatever the operating conditions, • Strong influence of the air-fuel ratio on NOx emissions, • Influence of the furnace temperature on NOx and combustion efficiency • Low effect of thermal input on NOx • Strong influence of the percentage of exhaust gases through the burner on the combustion efficiency • Design tools necessary to implement this new combustion technique (product quality, efficiency, …) Franck DELACROIX - ADEME

14. Other studies of the heating equipmentDetailed measurements in the flame • Reference operating conditions • thermal input = 200 kW, • preheated air = 1000 °C • furnace temperature = 1300 °C • air / fuel ratio = 1,1 • Parameters followed • temperature • species • velocity • heat transfers Franck DELACROIX - ADEME

15. Study of the heating equipmentDetailed measurement in the flame – main results Fields of CO concentration and mean temperatures Fields of the mean temperatures Chemiluminescence emission of the OH* radical Franck DELACROIX - ADEME

16. Simulation of the flameless combustion mode Pre-dimensionning of slab reheating furnaces Existing software has been adapted by the Polytechnic Faculty of Mons and IRSID to simulate the installation of burners working in the flameless combustion mode into any area of a furnace. Considering the stationary regime, this tool showed that : - a decrease in fuel consumption by 8,5% can be expected installing this new type of burner in the preheating zone of an existing furnace instead of conventional burners, - the design of a new furnace only fitted with this kind of burner could increase the productivity by 17% and decrease the fuel consumption by 14% . Franck DELACROIX - ADEME

17. Simulation of the heating equipment and representation simplification • CFD approach has been chosen • The methodology employed is: • to pre-select the sub-models used to represent the industrial burners • to validate them with the detailed in-flame measurements ■ Simplification : accuracy/calculation-time compromise, in relation to the detailed model, • Conclusions implemented to simulate the test furnace at semi-industrial scale in the dynamic regime Franck DELACROIX - ADEME

18. Test at semi-industrial scale and validation of the tools • Objectives: • to validate the modeling tools developed in parallel • to assess the performance of the flameless-oxidation burners in conditions close to an industrial furnace • to acquire a technical expertise to scale up this technology in the industry Franck DELACROIX - ADEME

19. Test at semi-industrial scale and validation of the tools • The combustion efficiency is over 85% in the reference operating conditions • The pulsed regulation mode is very good for the burners control (in terms of heating quality and NOx emissions) • The burners enable to achieve a very good thermal homogeneity • These tests represent a very useful database for the validation and the specification of the simulation tools limits Franck DELACROIX - ADEME

20. Soaking zone Heating zone Billets exit Billets entrance Preparation of a demonstration project at industrial scale Existing slab reheating furnace Objectives : production capacity increase, while improving efficiency and reducing NOx emissions. CFD assessments showed that the installation of two pairs of 3MW burners upstream the heating zone gives the most interesting results Franck DELACROIX - ADEME

21. Preparation of a demonstration project at industrial scale Example of simulation for the reheating furnace Mean temperature fields Franck DELACROIX - ADEME

22. Conclusions & perspectives 1/2 • Regenerative burners used in the flameless combustion mode are high-performance systems allowing to significantly increase the productivity as well as reduce the CO2 emissions, • Measurements have also shown that low NOx emissions can be achieved ( below 300 mg/m3(n) at 3% of O2), whatever the operating conditions, • Several manufacturers are now offering this type of burner, • Industrial demonstrations in Europe, in various sectors especially metallurgy, should appear in the coming months, • The design tools developed in the framework of the INTERNOx project , but also a better understanding of the combustion phenomena enable guarantees to be given regarding the performances and heating quality of the products, • It is very likely that this new combustion mode will also be used, in the short or medium term, in other industrial sectors such as ceramics, glass-making, petrochemicals, gas turbines or industrial boilers. Franck DELACROIX - ADEME

23. Conclusions & perspectives 2/2 • In the medium term, it will be thus a concern less during the BAT determination process, as it will no more be necessary to make a trade-off between energy efficiency, productivity and NOx emission reduction... Franck DELACROIX - ADEME

24. Thank you for your attention Franck DELACROIX - ADEME