News
News from year: 2019
02/08/19
EAF Fume-Treating solutions and Noise Control
During the last 40 years, Danieli has continuously improved its environmental technologies by refining the design of the equipment (considering "real-time" feedback coming from the plants), adopting innovative solutions and choosing premium-quality suppliers for "noble" parts. This has become crucial, as the requests from the customers and from environmental agencies have become more and more challenging.
During the last 40 years, Danieli has continuously improved its environmental technologies by refining the design of the equipment (considering "real-time" feedback coming from the plants), adopting innovative solutions and choosing premium-quality suppliers for "noble" parts. This has become crucial, as the requests from the customers and from environmental agencies have become more and more challenging.
This is confirmed by the fact that, together with dust, the control of other pollutants has become important too: dioxins are one example.
Without any abatement, a scrap-based EAF can emit more than 5 ng I-TEQ/ Nm3. With a quenching tower, dioxin emissions can be reduced to less than 0,5 ng I-TEQ/Nm3, and with the injection in the ducts of special reactants (e.g., activated carbons, lignite, clay minerals, etc.) it can be further decreased to values lower than 0,1 ng I-TEQ/Nm3.
Abatement for NOx, SOx, and CO content at the stack outlet also are investigated.
NOx can be cut down by an SCR but can also be reduced by good EAF practice, like slag door closed or a fast-covered arc.
SOx is linked to the quality of raw materials (scrap, carbon) but can be reduced through duct sorbents injection CO is linked to the efficiency of post combustion, therefore a suitable temperature (>800°C) as well as an appropriate residence time in the post combustion chamber should be ensured.
But the pollutants mentioned so far are not the only ones that can be found in a steel meltshop: noise is a type of pollution, too.
Danieli provides several solutions for noise reduction, like dog houses, elephant houses, fan casing insulation, and silencers in the fan deliveries (before the stack).
This last solution is well known in the market and frequently used, but Danieli has developed an alternative solution also, one that is under patent procedure and that eliminates some of the problems commonly found in standard installation.
The silencers that have been adopted since the 1980s are comprised of multiple parallel baffles made of semirigid, mineral-wool panels wrapped by perforated steel plates. The noise-absorbing effect of these panels is very good, but the main disadvantage is the persistent loss of the mineral wool fibers, due to the continuous vortex generated downstream the fans outlet.
Aiming to solve this fiber dispersion, Danieli has elaborated the solution of omitting the mineral wool panels.
Combining the blades' frequency, surface roughness, different materials and outlet and stack geometry in an appropriate way, it's possible to obtain significant noise reduction without using the common parallel baffles.
This underlines the fact that innovation is critical not only for core equipment of a steel meltshop (EAF, CCM, etc.), but also for the "environmental equipment", especially considering that compliance with environmental standards is becoming a primary topic for steel producers as they aim to achieve sustainable steel production.
This is confirmed by the fact that, together with dust, the control of other pollutants has become important too: dioxins are one example.
Without any abatement, a scrap-based EAF can emit more than 5 ng I-TEQ/ Nm3. With a quenching tower, dioxin emissions can be reduced to less than 0,5 ng I-TEQ/Nm3, and with the injection in the ducts of special reactants (e.g., activated carbons, lignite, clay minerals, etc.) it can be further decreased to values lower than 0,1 ng I-TEQ/Nm3.
Abatement for NOx, SOx, and CO content at the stack outlet also are investigated.
NOx can be cut down by an SCR but can also be reduced by good EAF practice, like slag door closed or a fast-covered arc.
SOx is linked to the quality of raw materials (scrap, carbon) but can be reduced through duct sorbents injection CO is linked to the efficiency of post combustion, therefore a suitable temperature (>800°C) as well as an appropriate residence time in the post combustion chamber should be ensured.
But the pollutants mentioned so far are not the only ones that can be found in a steel meltshop: noise is a type of pollution, too.
Danieli provides several solutions for noise reduction, like dog houses, elephant houses, fan casing insulation, and silencers in the fan deliveries (before the stack).
This last solution is well known in the market and frequently used, but Danieli has developed an alternative solution also, one that is under patent procedure and that eliminates some of the problems commonly found in standard installation.
The silencers that have been adopted since the 1980s are comprised of multiple parallel baffles made of semirigid, mineral-wool panels wrapped by perforated steel plates. The noise-absorbing effect of these panels is very good, but the main disadvantage is the persistent loss of the mineral wool fibers, due to the continuous vortex generated downstream the fans outlet.
Aiming to solve this fiber dispersion, Danieli has elaborated the solution of omitting the mineral wool panels.
Combining the blades' frequency, surface roughness, different materials and outlet and stack geometry in an appropriate way, it's possible to obtain significant noise reduction without using the common parallel baffles.
This underlines the fact that innovation is critical not only for core equipment of a steel meltshop (EAF, CCM, etc.), but also for the "environmental equipment", especially considering that compliance with environmental standards is becoming a primary topic for steel producers as they aim to achieve sustainable steel production.
Autore: DJ