The lining of large furnace is usually made of materials with light weight, high strength and good thermal insulation performance, which greatly reduces the weight of furnace lining. All the refractory castables are packed by the manufacturer and transported to the site. After mixing with water, they can be used.
1Refractory castables for pouring construction should be selected according to local conditions, and the pouring method is different with different structural parts. Choosing reasonable construction method is the key to ensure quality, construction period and reduce cost
1) preparation before construction
the mix proportion test block should be well prepared, and the construction can only be carried out when the test block meets the design requirements;
2) check the corrosion of the steel shell, and remove the rust on the steel shell surface contacted by the castable;
3) check whether the formwork is firmly supported. The surface of the formwork shall be planed and painted with
2,Pouring of refractory castables
1) when the refractory castables are poured in the insulation layer, manual tamping should be used to prevent particle separation and increase the bulk density. When the thickness is greater than 75mm, the required thickness should be achieved in one pouring, otherwise, delamination will occur. Joints shall be clean and continuous.
2) when pouring refractory castables in refractory layer, mechanical tamping should be adopted to achieve solid inside and flat outside. Manual tamping should be uniform and dense, but not polished. Because after calendering, the cement slurry will not only return upward, but also make the surface more compact, so the internal water is not easy to evaporate, and cracks are easy to occur. Therefore, it is necessary to prevent the water from evaporating too quickly. After the construction, it should be covered to keep it moist for maintenance.
3) when pouring refractory castable at furnace bottom, it is enough to compact it with wooden trowel, and there is no need to polish it, otherwise cracks will occur.
4) when pouring refractory castables, no matter it is refractory layer or insulating brick, when the insulating brick masonry has contact surface, measures should be taken to lining plastic film or other materials to prevent water absorption and adverse isolation.
5) when there is a contact surface between the refractory castable and the insulation board (brick), a layer of plastic cloth should be laid to prevent water absorption. For refractory castables with difficult corner, the amount of water pouring castables at the bottom of the furnace can be increased appropriately, but not too much. When using refractory castable with good fluidity, tamping time should not be too long to prevent particle separation and excessive moisture from returning upward, which will cause cracks due to evaporation of moisture.
6) when the thickness of castable is less than 50 mm, the coating method should be used to finish the coating at one time. During the construction, the castable should be filled with the steel wire mesh, and there should be no voids. It is required to be dense and the volume weight should not be increased. When daubing, the castable should be spread out and then smoothed with a wooden trowel to make the surface rough. In order to prevent cracks, the surface of castable should not be polished with iron trowel.
