Working environment of pelletizing vertical furnace lining and selection of refractory materials

The working environment of different parts of the pelletizing vertical furnace lining is different, and there are different requirements for the selection of refractory materials, as follows:

1. Combustion chamber

•Working environment: withstand high temperature of 1100-1120℃ and pressure of 10-20kPa, positive pressure operation, high sealing requirements, otherwise it is easy to leak gas and fire and cause burn-through accidents. It is also affected by the horizontal thrust of the arch foot and the gas side pressure of the furnace wall. The shutdown of the vertical furnace causes the masonry to expand and contract repeatedly, which is easy to crack.

•Selection of refractory materials: Generally, clay bricks or high-alumina bricks are used for masonry, 701 mortar is used for important parts such as the arch, and general mud is used for the furnace bottom and other parts. Refractory plastic can also be used for integral tamping.

2. Wind guide wall

•Working environment: It is supported by metal water beams below, often affected by high temperature, scouring and wear of dusty airflow, and also bears the side pressure of the furnace charge. The masonry at the junction of the water beam and the masonry, especially the masonry at the bottom 1m, is most likely to fall off.

• Refractory material selection: generally use high-quality clay bricks, high-alumina bricks or yellow corundum bricks, and corundum silicon carbide composite bricks can also be used, which are wear-resistant, erosion-resistant and have good thermal shock stability.

3. Baking zone

• Working environment: The pellet temperature can reach about 1250℃. In the high-temperature oxidizing atmosphere, various chemical reactions will occur. The CaO decomposed by carbonate will corrode the lining bricks, and the lining bricks will crack under the action of thermal stress. The friction of the downward movement of the pellets and the erosion of the rising air flow will cause the loose surface layer to fall off. When the quality of the green balls is poor, it is easy to damage the lining bricks by nodules.

• Refractory material selection: Refractory materials with strong chemical erosion resistance and dense structure should be selected. High-alumina bricks are mostly used in newly built pelletizing vertical furnaces in China.