Plastic construction methods and precautions
Refractory plastics can be used in heating furnace walls, furnace roofs and other parts, as well as its easy construction and other characteristics, can be used in some special parts such as castables that are difficult to construct. The plastic construction requires uniform and dense, full combination and continuous construction.
Taking the plastic construction of the furnace roof as an example, the construction method of plastic is briefly described.
During the ramming process, the placement quality of the anchor bricks has a great influence on the service life of the plastic stove top. During construction, the plastic can be rammed to about 20mm beyond the pay-off point (pre-measurement Line on the hanging trabeam), place the corresponding wooden mold bricks and drive into the plastic to form a concave and convex surface, and then insert the anchor bricks to fix it. The gap between the anchoring brick and the hanging trabecular is wedged with wooden wedges before laying plastic for ramming.
The hanging anchor bricks are placed in the correct position, and the bricks are placed vertically. When ramming, first hit the two sides of the anchor brick with a rammer, and then hit the plastic between the two hanging anchor blocks. After repeating this twice, lay the lower layer and continue the construction. After the roof can be plasticized, remove all the wooden wedges after the oven is finished.
Precautions for plastic construction
(1) When the construction is intermittent, the joint should be left at the centerline of the same row of anchoring bricks and the ramming surface should be covered with a plastic sheet. When ramming is continued, the rammed joint surface should be scraped off by 10-20mm, and the surface should be shaved; When the pounding surface dries too quickly, the spray water gets wet.
(2) The plastic can be cured naturally, and the mold should be removed as soon as possible before the oven to dry the masonry naturally. Use a wooden hammer to lightly tap the plastic around the end face of the anchoring brick before trimming the plastic mold to make it bite tightly, and use a unified special tool for trimming.
(3) The formwork at the closing door of each section of the furnace top must be removed 24 hours after the completion of the plastic construction.
(4) The expansion joint is cut out with a special slitting knife, and it is cut every 1500mm with a depth of 60mm.
(5) The refractory materials used for the furnace top in the high and low temperature sections are different. During construction, the boundary line between the high and low temperature sections is drawn on the trabecular, and the material is replaced with this boundary line.
(6) Before the oven, the cracks in the plastic lining can be excavated and repaired when the cracks are larger than 12 mm. The cracks should be dug into wedge-shaped openings that are large inside and outside. When the crack is 3-12mm, it should be filled with refractory fiber.
(7) Construction of furnace top heat insulation castables. The castable construction can be carried out after the plastic construction of the furnace top is completed. Ideally, however, construction should be carried out after the furnace has been running for several days to cool down. Before the construction of the oven, it is necessary to reduce the water consumption to a certain extent, and stir it to dry it, so as to prevent the water from running around the anchor bricks and seeping into the oven.