Explanation of thermal balance control for high current intensity and current density in 400kA electrolyzers

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A 400kA electrolyzer – with such a high current intensity and high current density, thermal balance is undoubtedly the biggest problem. Thermal balance control boils down to two points: 1. Reducing heat input. Reduce the pole pitch to lower the slot voltage. 2 Increase heat expenses. There are many things that can be done to dissipate excess heat. To this end, the following optimizations have been made in design and production: 1. Optimize the busbar configuration – while ensuring the stability of the electrolyzer, reduce the pole pitch as much as possible in order to decrease heat generation. Currently, the graphitization tank is at 4.18 V, and the 30% graphitic tank is at 4.15 V. 2 Technologies such as a combination of ventilation for the electrolysis plant and overall thermal balance of the electrolyzers, integral welding of the cradle frame to the cell shell, welding of heat dissipation fins on the outside of the cell shell, welding of the cradle frame to the cell shell for the smaller surfaces of the electrolyzers, and placing both the cell shell and the lining entirely below the operating surface were employed to ensure the thermal stability of large-scale electrolyzers and improve the working environment ； The furnace side wall is over 10 cm thick, with the shell temperature at 280–300 degrees. 3 Use a properly blended covering material to reduce its height. 4 The steel claws and rods increase the cross-sectional area, reducing resistance and heat generation while increasing heat dissipation. 5 Graphitized cathodes and highly graphitic cathodes are used to reduce the pressure drop at the furnace bottom, decrease heat generation, and increase heat dissipation. 6 The use of segmented flue ducts improves gas collection efficiency and increases heat dissipation. From production experience: The voltage in 400kA electrolyzers using graphitized cathodes is on the high side; the pole spacing is about 3 mm higher than that in semi-graphitic electrolyzers. The thickness of the furnace walls is 10–12 cm, and the temperature of the cell shell is 280 degrees. There is still potential to increase the current intensity further – it should be possible to raise it by 10,000–20,000 amps, reaching an intensity of 410–420 kA. An electrolyzer with a 30% graphite cathode and a current capacity of 400 kA features an electrode spacing of 4.5 cm, furnace walls about 10 cm thick, and a tank shell temperature of 300 degrees. By reducing external voltage drops – such as those caused by steel clamps, ferrophosphorus elements, or connections at the column busbars – it is possible to increase the current intensity further. However, this requires high standards from the production operators, who must carry out their tasks with precision and control.