Objective
Acciai Speciali Terni intended to reduce the energy consumption and the NOx emissions from the annealing furnaces of the cold rolling mill for stainless steel in Terni works. The plant includes two lines in parallel, each consisting of annealing furnace, shot blasting and pickling. The furnace of the A&P line 1 is equipped with central heat recovery, while the furnace of the A&P line 2 was an old plant without recovery. This allows comparison with two basic designs of conventional gas firing equipment.
The natural gas consumption is to be cut down approximately from 68 m³ nat gas/ton steel to 35 m³ nat. gas /ton steel. I.e. from +/- 5 Mio m³ nat.gas/year to +/- 2.5 Mio m³ nat. gas /year, with a corresponding reduction of 5000 ton/year of Co2 released into the environment, together with NOx emissions < 200 mg/Nm³, well below the most restrictive regulations.
The regenerative burner REGEMAT proved to be very satisfactory in the operating conditions of the annealing furnace (up to ca. 1150 °C); this regenerative design has been conceived for high temperature duty and behaves better then auto-recuperative burners (also tested during the initial trials in the framework of the project) that use metallic components as heat exchanger. Energy savings is based on air preheat close to the maximum theoretical value, corresponding to a thermal efficiency of the order of 85%. With respect to the old plant without recovery, fuel consumption is reduced down to < 45% with an equivalent reduction of atmospheric CO2 release. This reduction is in the order of 2.5 Mio m³ per year of natural gas, but will grow in the near future thanks to higher plant productivity. The productivity of the new furnace equipped with the new technology proved to be substantially enhanced, i.e. almost double than the original, well above expected, while still keeping satisfactory quality of the annealed strip. concentration of NOx in the flue gases has been abated by a factor 4, so that taking into account the energy savings, NOx emissions per ton of steel are reduced in a spectacular magnitude (a factor of 8). Together with NOx suppression from downstream pickling equipment, thanks to nitric acid free operation, the new A&P process can now be considered "NOx free". Further important results concern the process control strategy of the new firing equipment and potential improvements of the enhanced product quality. These are now key issues for the new technology as applied to similar A&P lines in the field of heat treatment of stainless steel and, possibly, non ferrous metals. The FLOX principle as well as design of regenerative combustion decentralized to the burner may be extended and adapted to several high temperature processes after suitable R&D action. Successful feasibility of the present project has considerably promoted these optimistic expectations.
In the cold rolling of stainless strips continuous furnaces are used for annealing the strip between rolling passes. The plant proposed for the project is equipped with an obsolete firing system without any heat recovery. The new advanced burners are capable of very high air preheat (up to 90% of the process temperature) which is obtained by means of the known regenerative principle, i.e. of thermal capacities alternatively crossed by combustion air and by flue gases. The new compact gas burners, incorporate a very efficient air regenerator and use advanced ceramic nozzles for high temperature duty; they have been developed by the project partner WS to R&D stage for operation in a new firing mode without visible flame (FLOX), which allows very low NOx emissions, unlike conventional burners where NOx increases very much with increasing air preheat. These new burners require proven industrial price for high temperature gas-fired processes. They had not yet been tested in field conditions and were therefore still pre-competitive at the beginning of the project. The new firing system was to be tested on the annealing furnace, operated on continuous duty, by revamping the existing equipment. The project should prove the feasibility of industrial operation of the new burners and of the related combustion control equipment, by confirming not only the expected reduction of fuel consumption and of NOx emission, but also reliable performance and feasibility test, the new technology will be directly applicable to similar furnaces and to a large variety of industrial high temperature processes in steel works and non-ferrous metallurgy as weel as in other industrial sectors (ceramics, glass melting, process furnaces...)
Fields of science (EuroSciVoc)
CORDIS classifies projects with EuroSciVoc, a multilingual taxonomy of fields of science, through a semi-automatic process based on NLP techniques.
CORDIS classifies projects with EuroSciVoc, a multilingual taxonomy of fields of science, through a semi-automatic process based on NLP techniques.
- engineering and technologyenvironmental engineeringenergy and fuelsfossil energynatural gas
- social scienceseconomics and businesseconomicsproduction economicsproductivity
- engineering and technologymaterials engineeringceramics
- engineering and technologymaterials engineeringmetallurgy
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Call for proposal
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DEM - Demonstration contractsCoordinator
00100 Roma
Italy