Selection of Material and Shape of Grid Bricks for Glass Kiln Regenerators

Grid bricks are an important component of heat storage and transfer in a heat storage chamber, requiring them to be resistant to high temperatures, corrosion, more heat storage, fast heat transfer, and good resistance to rapid cooling and heating.

The measurement of the heat storage effect of a heat storage chamber is usually determined by the size of the heating area of the grid, which is the surface area of the grid that can carry out heat exchange. The larger the heat storage area, the more heat is accumulated and the more heat is released, which can fully increase the preheating temperature of air and gas, and is more beneficial for fuel combustion.

Different alkaline grid bricks are used according to the different temperatures and fly ash content of the top, top, middle, and bottom parts of the heat storage chamber.

The top (above 1400 ℃) is prone to forming a liquid phase with the bricks due to high temperature and a large amount of flying materials, which can easily adhere to flying materials and cause stress on the bricks. Therefore, The top is made of zirconium bricks with excellent creep resistance at high temperatures or 98% high-purity magnesium bricks (due to the reaction between MgO in the high-purity magnesium bricks and the ultrafine powder SiO2 that fly into the regenerative chamber, low-temperature eutectic substances are generated. Therefore, zirconium bricks are mostly used for the top lattice of 1 # and 3 # that are easy to enter the fly material, and 98% high-purity magnesium bricks are mostly used for the end regenerative chamber lattice that is not affected by the fly material).

The upper part (10001400 ℃) has less settling of fly ash, and high-purity magnesium bricks can be used.

The fly ash in the middle (8001000 ℃) is already scarce, but it is a sulfate condensation area that easily causes magnesium bricks to react with the fly ash to form magnesium silicate (MgSiO3). At the same time, the SO2 and SO3 formed during the mirabilite reaction process and fuel combustion process in the batch are also prone to react with magnesium oxide:

MgO+SO2 → MgSO3 MgO+SO3 → MgSO4

The generated magnesium sulfate or Magnesium sulfite repeatedly solidifies and liquefies, and the volume expansion causes the structural damage of the magnesium brick, so the direct bonded magnesia chrome brick (DMC-12) with good thermal stability and low porosity is selected for this part (magnesia chrome brick is not allowed to be used in areas with high environmental requirements, and periclase+magnesia olivine brick is often used).

The temperature at the bottom (below 800 ℃) alternates between cold and hot, with significant load and less erosion by alkaline materials. Therefore, materials with good thermal stability and load-bearing strength are required, usually using low porosity clay bricks (DN-12, DN-13, or DN-15) or silica bricks. If the performance of various alkaline bricks is not taken into account and used in general, it will affect other grids when one part of the grid is damaged, thereby reducing the overall lifespan of the grid. Most alkaline Fire brick, including magnesia chrome bricks, are easily damaged in the atmosphere containing cracked hydrocarbons (reducing atmosphere). Therefore, alkaline bricks can only be used in air storage chambers and cannot be used in gas storage chambers.

For the regenerator lattice that is vulnerable to the erosion of flying materials, the common lattice brick configuration from bottom to top is as follows: low porosity bonded brick or sillimanite brick → direct bonded magnesia chrome brick or magnesia zirconia brick or magnesia olivine brick containing 12% chromium → 96% high-purity fused magnesia brick → 98% high-purity fused magnesia brick → 24 layers of magnesia zirconia brick (VZ) or sintered zirconia corundum brick; In order to save investment, the last 12 pairs of regenerative chamber grids with less erosion of fly ash can be directly stacked with 98% high-purity fused magnesium bricks at the top instead of using magnesium zirconium bricks or sintered zirconia corundum bricks.