Burners for Reheating Furnaces
Burners are perceived as the quality factor of the reheating furnaces, therefore Italimpianti develops internally and produces the burners for its furnaces.
Burners portfolio includes 12 different burners types from 0,15 to 7,5 MW.
The R&D departments is focusing on the development of new burners for achieving the best product quality while reducing NOx emissions and reducing fuel consumption.
Tenova designs and supplies its own in-house advanced burner technology as a component of most reheating furnace projects.
Its burners integrate the expertise of its engineering team and advanced research tools in the combustion field. References about this technology are clear: thousands of burners made in Tenova were sold by the '60s to today.
Installation of high-performance furnaces has led to the development of the Flexytech® burner product line. As the best available technology on the combustion systems market, the new generation of Tenova FlexyTech® flameless burners offers dramatic reductions in NOx emissions. Flameless technology is also applied to regenerative burners, to deliver top performances for both NOx emissions reduction and energy savings.
Tenova Italimpianti has taken a giant leap forward in industrial burner operating and environmental performance with the FlexyTech® TRGX flameless regenerative burners. The new burners' strong point is associated with the environmental benefits of Flameless technology which guarantees drastic NOx emission reductions, with the high energy efficiency of fume heat recovery regenerative burner technology. The burner is the technological heart of the industrial furnace and must carry out the production process, meeting the goals that used to be antagonists: high heating or treatment quality, reduce energy consumption and low NOx emissions.
Regenerative flameless burners are now the answer that exceeds compromising solutions. It is a technology developed by Tenova that sets a new absolute standard in terms of operating and environmental performance. Indeed, energy efficiency and reduced emissions are converging goals that guide new investment choices. TRGX regenerative flameless burners are the most recent evolution in the research program launched in the last decade by Tenova Italimpianti. A key intermediate step was the development of TSX flameless burners able to drastically reduce NOx emissions under 35-40 ppm compared to traditional burners' 120-150 ppm.
Flameless combustion, obtained with a diluted mix of air and natural gas inside the furnace, guarantees higher combustion uniformity than the "linear flame" process thus highly reducing the formation of NOx even at high temperatures, over 1300° C, reached in heating furnaces. A result fully confirmed since the first industrial application of Flameless technology, in 2003 with a 125t/h Walking Beam Furnace at Rocky Mountain Steel (USA), that still maintains an average NOx emission level under 40 ppm. If the possibility of preheating process air to high temperature is added to flameless combustion, the furnace's energy efficiency significantly increases.
This is what occurs with TRGX regenerative flameless burners that recover an important part of output hot fume energy content through a ceramic regenerator made up, according to the case, of a honeycomb or alumina packed balls structure. The regenerative effect occurs in two steps. Hot fumes are forced to flow through the ceramic regenerator which, due to the high specific surface, accumulates almost all fume heat. When heat accumulation reaches the correct level, the flow is reversed and cold combustion air cross the hot beehive to then enter the furnace at a temperature over 1000° C.
Air preheating significantly increases the furnace's heat efficiency which can reach up to 80% compared to the 60% of a furnace with traditional burners and centralised recovery system. With the same fuel supply, furnace productivity can increase up to 20% and this means that, with the same required performance, the size of the furnace can be reduced with advantages in terms of initial investment but, more importantly, in operating costs. Specific energy consumption per product tonne is reduced by about 10% and, considering the high volumes of gas used, savings become extremely interesting.
So much so that the higher investment cost, due to the need to use twice the amount of burners required for the same furnace size, is amortised in just a short period of time. Operating data collected from regenerative furnaces produced in recent years amply confirm the test data and open the road to new energy efficiency and emission reduction improvements.
The Tenova Italimpianti R&D road map is increasingly more focused on improving the combustion process to expand the possibility of maintaining the same performances using fuels tied to the ironworks process in alternative to natural gas, even including BFG characterised by high heat power, ten times lower than natural gas. Today, a reliable and fully safe regenerative technology that only uses BFG is not yet available. As a further step forward and pushing the effects of diluted combustion to the extreme, the Tenova Italimpianti R&D team is now addressing the "One Digit Emission" challenge, with the goal of dropping average NOx emissions under the 10 ppm limit.
The analysis of laboratory test correlations and the definition of increasingly more powerful mathematical models has, in fact, further improved know-how on physical and chemical phenomena tied to combustion and we will soon be able to create a new generation of flameless burners with performance considered unattainable until now.