Glass furnaces · 2026-10-24
Magnesia and magnesia-zirconia in regenerators: fuel and flue gas
Magnesia brick stores heat in periclase and resists erosion, and is the foundation of the regenerator. Magnesia-zirconia, with zircon added, gains thermal-shock resistance and resistance to sulphur dioxide, and suits the crown of a large float-glass furnace that is not fired with petroleum coke.
A regenerator returns the heat of the flue gas to the combustion air. The checker material must first be able to store heat, and then to take gas erosion and a periodic reversal of temperature. Magnesia brick, with periclase as its main crystalline phase, stores heat well and resists erosion, and is therefore the foundational material of the regenerator, graded by magnesia content.
The top checkers have still to face sulphur dioxide and thermal shock. Introducing zircon into a magnesia matrix gives magnesia-zirconia brick: the phase change and expansion contrast of ZrO₂ improve thermal-shock resistance, and raise resistance to SO₂ and to flue-gas erosion. In a large float-glass furnace that is not fired with petroleum coke, this brick belongs at the regenerator crown — where an acidic load is present, but not yet at the severity that vanadium from petroleum coke would impose.
Under petroleum-coke firing, the crown should turn to chrome-corundum. The regenerator is not served by a single “magnesia brick”: magnesia covers the main checkerwork, magnesia-zirconia the crown when the furnace is not fired with petroleum coke, and chrome-corundum the crown when it is. Fuel and position are what separate the three materials.