Refractory materials for heating furnaces are increasingly tending to be castables. Heating furnaces are divided into three categories: push-type, walking-beam and ring-type. Walking-beam furnaces are further divided into walking-bottom type, walking-beam type and composite walking-beam type.
The furnace wall of the walking-beam heating furnace adopts a composite structure. The furnace chamber is castable as a whole, the outer side is insulated with a composite insulation layer, the upper part of the furnace body is castable with clay, and the insulation layer is made of lightweight clay bricks. The upper part of the furnace body is castable with low cement. From the working surface to the outside, the furnace top is low cement castable (castable 230mm), aluminum silicate needle blanket (30mm), and anchor bricks are used at the expansion joint of the castable. The total thickness of the furnace roof is 330mm.
The furnace bottom uses magnesium bricks, clay bricks, and lightweight clay bricks, with a thickness of 534mm. The root of the fixed beam column and the opening where the walking beam column passes through the furnace bottom are divided into three layers, using lightweight clay castables and low cement castables. The upper part of the supporting beam and column pipe in the furnace is made of aluminum silicate fiber felt (20mm). A layer of waterproof ordinary plastic cloth is used for the outer cover, and then low cement castable is rammed. The lower part of the column pipe is also made of low cement castable.
The structure of the stepping bottom beam and the stepping beam is similar, but the difference is that the furnace bottom structure is different. A layer of phosphoric acid refractory prefabricated parts or phosphate castables are used to fix the bottom 300mm, and the movable bottom is made of lightweight high-aluminum bricks or lightweight clay bricks. The working surface uses phosphate steel fiber high-aluminum prefabricated parts.
The lining of the annular heating furnace is composed of 230mm thick low-cement castable and refractory fiber felt. The furnace bottom is composed of silicon carbide castable and clay bricks, lightweight clay bricks, and calcium silicon board.
In addition, plastics also have the characteristics of high temperature and thermal shock resistance, and are gradually used in heating furnaces. Especially in maintenance, the use is more obvious.
The composite structure of castables and insulation materials for the heating furnace lining is much better than that of refractory bricks. The integral casting has no brick joints, good integrity and strong airtightness. In addition, the anchor bricks connect the lining, which is more stable. Therefore, the use of castables is more extensive in heating furnaces.
