In order to comply with the requirements of new smelters built in warm countries or the upgrade of existing facilities, Fives' GTCs can feature a range of gas cooling solutions in addition to natural convection.
When temperatures reach 170 to 200°C at pot outlets (depending on pots amperage and ambient temperature), gases must be cooled down to secure the equipment (gaskets, gates, filtering fabrics) and to maintain a high HF adsorption efficiency by alumina.
Up to now, in every modern GTC, Fives includes air dilution technologies, which consist in mixing hot gases with a controlled volume of ambient air using modulating dampers to obtain the required gas cooling. However, if needed, Fives can also offer three other technologies to reach higher cooling levels. Any of these technologies can be coupled together to reach an optimal temperature reduction.
In partnership with Hydro and NTNU (Norwegian University of Science and Technology), Fives has developed and implemented very efficient heat exchangers with low fouling. In Fives’ heat exchanger, fumes circulate perpendicularly to the tube axle while cooling liquid circulates inside finned tubes.
A sustainable solution with high heat recovery potentials, which offers:
- High gas temperature drop (up to 50°C) without increasing the flowrate
- High compactedness solutions
- Low fouling
In a water injection system, water spraying is performed inside large-diameter ducts upstream of the GTC. In order to reach a good evaporation performance, water is sprayed in low-diameter droplets (< 100µm), using compressed air.
Fives has developed the expertise to integrate this gas cooling technology and the know-how to ensure that atomized water droplets do not come in contact with the inside walls of the ductwork, which would lead to corrosion or scaling.
A easy solution for existing plants, which includes:
- A significant temperature decrease
- An integrated anti-corrosion design
The temperature decrease is provided by hairpin-shaped ducts which artificially increase the distance covered by gases in ducts, enabling longer exchanges between ambient air and gases. This technique leads to an additional 5-10°C temperature drop.
A cost effective solution for new installations, which features:
- A natural increase convection between ambient air and gases
- An easy implementation
- A moderate temperature drop