The construction of refractory plastic is rammed with a tamping machine or a pneumatic pick. The construction of refractory ramming materials is similar to it.
1.Construction preparation
According to the design requirements, the furnace steel structure, reference line and holes and other parts shall be fully inspected and accepted, and construction can only be carried out after they are qualified. The construction department shall clean up the debris in and around the furnace, and transport the air compressor, construction machinery and scaffolding to the site. The air compressor is connected to the power supply and the test operation is normal. The following table shows the models and main technical indicators of the tamping machine and pneumatic pick. It can be directly used for ramming material construction. When ramming plastic, the hammer head needs to be equipped with a rubber pad. The construction tools also include trimming knives, seam cutters, air permeable chisels, wire brushes, pressing films with the same shape as anchor bricks, and wooden wedges for fixing anchor bricks.
Refractory plastic blanks should be stored in a cool warehouse. Before construction, their plasticity should be checked. Construction can only be carried out if they meet the requirements. A simple judgment method is to squeeze the plastic with your hands. If it is easy to knead into a ball without falling apart, it can be used.
When the furnace wall is not high, its insulation layer can be built at one time, otherwise it should be built in sections and layers; the construction of the furnace roof insulation layer can be done while tamping the furnace roof plastic lining, or the furnace roof plastic lining can be tamped and the insulation layer can be laid in a centralized manner or poured with insulation castables. The general principle is that when laying or pouring the furnace roof insulation layer, it is absolutely not allowed to bury the metal connectors of the hanging bricks in it, that is, to expose the parts to the air to dissipate heat and increase its life.
When constructing refractory plastic, the furnace wall does not need to support the formwork. If there are holes, the membrane needs to be supported, and some parts also need to support the formwork; the furnace roof needs to be supported with formwork; the size of these formworks should be accurate, the formwork should have strength and rigidity, and the support should be firm and not deformed; the scaffolding is generally supported while ramming and construction, and should be firm.
During the construction process, all types of work should cooperate closely. When the ambient temperature is below 10℃, cold protection measures should be taken. After the construction starts, it needs to be carried out continuously and uninterruptedly. If it must be interrupted, plastic cloth should be used to cover the knotted surface to prevent dehydration. If the shutdown time is long and the knotted surface is dry and hard, remove the dry and hard layer and brush it with a wire brush before continuing the construction.
During the construction process, according to the designed expansion joint position, the caulking material should be placed well, and the surrounding area should be carefully compacted.
2.Ramming Construction
When the refractory plastic furnace wall is reached, first lay the blanks tightly and flat, and only one layer of blanks is allowed. The working surface side should be protected from intact blanks, and the inner side is allowed to protect corner-dropped, damaged blanks or trimmed broken materials; secondly, use a tamping machine or pneumatic pick to ram, and the hammer head moves along the length of the furnace wall, and the hammer head surface should overlap about 1/4. Ram the entire blank surface 2~3 times, and then the next layer of blanks can be staggered, and then continue to ram, and so on; thirdly, when encountering anchor bricks, ram the furnace wall plastic to the upper surface of the anchor brick, dig out part of the material at the location where the brick is installed, place the pressure film, and drive it into the plastic. When the size of the anchor brick is reached, take out the pressure film and install the anchor brick. This will make the anchor bricks and refractory plastics fit tightly together to prevent fire from spreading, and also prevent the furnace wall from tilting inward or collapsing; Fourth, when there are holes, when the distance from the ramming surface of the furnace wall to the lower surface of the burner is about 100mm, firmly install the fetal membrane, lay the blanks layer by layer, and ram them layer by layer. When constructing each layer, first ram the blanks around the fetal membrane, then ram the blanks laid horizontally, and finally seal them.
The ramming construction of refractory plastic is generally carried out by a tamping machine, whose impact energy and impact frequency are slightly smaller, because it contains more water than the refractory ramming material, so it can also be rammed densely. It should be pointed out that the key to ramming construction is that the ramming direction must be parallel to the working surface of the kiln lining. In other words, the upright furnace wall must be rammed in the vertical direction, and the working surface of the furnace roof is in a horizontal state, so it must be rammed in the horizontal direction. This can reduce the stratification of the lining and increase the density of the lining. When ramming the refractory plastic furnace roof, first support the template with a width of about 600mm, which is a hanging template. At the same time, support the scaffolding, stack the materials, and the operator stands. First, lay a layer of refractory plastic blanks vertically, and then ram densely, and so on; secondly, when encountering hanging bricks, the treatment method is the same as the furnace wall anchor bricks. After the hanging bricks are installed, they are locked with wooden wedges between the hanging beams and the hanging bricks before snow accumulation construction; finally, remove the excess part of the upper surface of the furnace roof lining according to the designed thickness. Then you can set up the formwork again, step by step. When this section is completed, the first section of the formwork can be removed and used again.
Treatment of lining working surface
The treatment of the lining working surface refers to the technology or method of treating the working surface of the lining during the engineering or manufacturing process.
The treatment of the working surface of the refractory plastic lining mainly includes surface finishing, stripping, piercing exhaust holes and cutting expansion joints. This work is best carried out simultaneously with the ramming construction process. If the surface becomes dry, it can be moistened with water spray before processing. When ramming the refractory plastic furnace wall, the template is generally not supported, so the lining is written later than the design size, and the trimming knife must be used to cut off the excess part, which makes the surface trimmed. The cut plastic, if it is not dry, can be used on the inside of the working layer. The surface of the furnace top and holes is relatively smooth after demolding, so a wire brush is used to strip the hair to expose the internal pores to facilitate the removal of moisture.
The surface of the refractory plastic lining is pierced with a breathable needle, i.e. a steel chisel of f4mm, perpendicular to the working surface to pierce the exhaust hole. The depth of the hole is about 1/3 of the thickness of the lining, and the center distance of the hole is 150~250mm. Another function of the hole is to buffer the rapid expansion of the lining and prevent cracks or peeling.
The horizontal expansion joint of the refractory plastic furnace wall is cut with a slitting knife. When pulling out the knife, it should be done slowly to prevent damage to the surface of the lining. After the entire lining is processed, if the furnace cannot be dried in time, the working surface should be covered with plastic film to prevent dehydration and hardening, blocking the pores, and affecting the removal of moisture during the furnace drying.
Construction of refractory ramming materials
The construction of refractory ramming materials is generally done by ramming with a pneumatic pick, and its wind pressure cannot be lower than 0.49Mpa. The surface area of the hammer head is 50mm×(50~80)mm×80mm. Therefore, its impact energy and impact frequency are relatively large.
During ramming, the thickness of each material is 20~60mm. The pneumatic pick should be rammed vertically to the material surface, and it should be moved continuously in one direction quickly, and the hammer head surface should overlap about 1/3. The hammer head surface should overlap between each row and between rows to prevent leakage and knotting. After each layer of material is rammed 3~5 times and a dense whole is formed, the ramming surface is stripped, and the next layer of material can be laid for ramming, and so on. The role of stripping is to make the upper and lower layers tightly combined to prevent stratification.
Ramming construction should be carried out continuously. If there is an interruption, the ramming surface should be covered with plastic film to prevent dehydration. When re-constructing, it must be stripped or chiseled into a step shape before construction.