Removal of Iron Oxide With Superconducting Magnet High Gradient Magnetic Separation From Feed-Water in Thermal Plant

By the accident of Fukushima Daiichi Nuclear Plant, all the nuclear plants have stopped in Japan. As a result, the operation rate of thermal power plants has been increased. It caused growth in CO₂ emission, which requires some kind of countermeasure. We focused on the iron oxide scales deposited on the piping system and boiler which declines the heat exchange efficiency of thermal power plants. In this study we attempt to remove the iron scales from the piping system and the boiler to maintain the power generation efficiency. In the current thermal plant treated by All Volatile Treatment (AVT) the iron elutes to the feed water in the low-temperature part which changes into iron ion or the paramagnetic fine iron oxide particles. On the other hand at the high-temperature part the main component of the scales is large ferromagnetic particles of magnetite. Therefore the magnetic separation at the high-temperature part is the more effective to remove the scale than that at the low-temperature part. For the reason, the existing method using the electromagnetic filter placed in the low-temperature part is not effective to remove the scales. We studied the high gradient magnetic separation (HGMS) at high-temperature part to remove a large amount of the scale. In this study, we assumed to install the HGMS system using the superconducting magnet at the inlet of the boiler.