On the one hand, the brick gap and slag erosion:
Brick joints between refractory bricks, not only for the operating state of high temperature molten slag infiltration and erosion provides a channel, but also this slag erosion itself also prompted the brick joints continue to increase. Both of these effects result in a large surface of slag in contact with the sides of the refractory bricks and cause the bricks to be overstressed on the sides during each cycle of heat-induced contraction and expansion. The slag in the brick joints has an erosive effect on the bricks not only along the radial direction, but also along the circumferential direction. Especially in the presence of circumferential cracks in the flanks, the circumferential erosion is faster, causing block spalling on the surface. Therefore circumferential cracks have a greater impact and influence on the life than radial cracks.
On the other hand, it is the relative displacement between bricks:
Due to the various layers of bricks in the gasifier heating or cooling process, the temperature rise and fall rate is different, as well as in the occurrence of thermal displacement process by the constraints and resistance is different, will make the brick to brick relative displacement.
This relative displacement will produce friction shear force on the displacement surface of the brick and brick and has a localized tearing effect, resulting in surface cracks. These surface cracks expand at each subsequent displacement, and the surface spalls due to the erosive spread of molten slag and reducing media in the cracks, and the brick displacement process itself accelerates the erosion of slag in the cracks.
Reducing or eliminating block spalling will substantially increase the life of refractory bricks. When the surface depth of more than 1.5mm, and has a certain area of block form crater, that is, the refractory brick damage to block spalling is considered to be the main; and less than 1.5mm, we believe that the erosion caused by ablation is the main cause of the erosion.
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