Semi-dry spray repair method?

Semi-dry spraying repair technology for coke ovens: Wet spraying repair requires adding 40%-50% water, while modern spraying repair materials allow for the use of only about 12% water. Since the spray material used in spray patching has a low moisture content, it is referred to as semi-dry spray patching technology. The working temperature of this type of spray repair material can reach 1400°C, and due to their different particle sizes, they can be used to repair damage ranging from minor flaws to situations where entire bricks have fallen off. China has introduced and adapted the semi-dry spray repair technology from Germany. The semi-dry spray repair machine is equipped with a continuous adjustment device, allowing the operator to precisely control the amount of material fed, and it can handle a variety of coke oven damages, ranging from the smallest to the most severe. The equipment is equipped with inlet hoses for compressed air and mixed water. The manual mixing device at the feed end of the spray gun is the most critical component; the needle valve on it is used to adjust the proportion of water required for repair. The water content depends, on the one hand, on the amount of water needed by the raw materials, and on the other hand, on the thermal radiation from the carbonization chamber toward the spray gun. Select the appropriate nozzle length according to the location of the surface to be repaired, and tighten it onto the mixer. The material is humidified in a mixer and transported via a nozzle to the damaged area. Generally, the nozzle is adjusted to an appropriate angle, and ladders and supports are needed during operation to hold up the long and heavy spray gun. There are also scrapers of various lengths, used to level the areas that need repair, along with vacuum hammers for cleaning damaged surfaces. The repair steps are as follows. ①Before spraying, check and confirm that equipment such as semi-dry spraying machines and tools are in good condition and complete, and that water, electricity, and power air meet the requirements for operation. ②Before repairing the damage, it is necessary to thoroughly clean the affected area; a considerable amount of impurities can often be found there, including old repair materials, molten bricks, slag, graphite, tar, and some loose tiles. ③Use a pneumatic hammer to clean the graphite, mortar, and other substances from the surface to be repaired. The air pressure used for cleaning is 0.4 MPa; cleaning is carried out until the working surface is clean, in order to avoid damaging the masonry. To prevent the air hammer from being damaged by prolonged heating, it should be placed in an oil tank for cooling every 4-5 minutes. ④After cleaning is complete, remove the cleaning device and proceed with shot blasting. Before spraying, connect the spray gun, water supply, electricity, and power air, and pour the spraying material into the hopper of the spraying machine. The spray patching machine and gun are operated by dedicated personnel, who start the machine by first turning on the gas, then feeding in the material for spraying, and finally turning on the water. The spray gun operator slowly adjusts the control valve in front of the mixer, so that the slurry applied to the surface being repaired is fine and uniform, does not fall off, and does not dry out. ⑤During spray patching, keep the nozzle about 100–300 mm away from the wall surface, at an angle of approximately 45°–90° to it. Move the nozzle tip from bottom to top, and apply the patch in layers depending on the degree of damage in that area; do not try to complete the patching at a single point at once. ⑥The mud sprayed onto the wall surface should be leveled and compacted with a shovel at the appropriate time, depending on its degree of dryness, so that the sprayed repair surface does not rise above the adjacent wall surface. ⑦For the spray patching on the repair surface, in addition to smoothing it out at the end, it may also need to be sanded flat if necessary. ⑧After repair, the carbonization chamber must be heated to the operating temperature, and it should be burned empty for at least 2 hours before coal is loaded, to ensure the necessary sintering time and effectiveness of the repair material. ⑨After the spray coating is completed, first stop feeding the material for spraying, then purge the material pipe thoroughly before turning off the power air supply; after that, rinse the spray gun clean and then turn off the water supply. Before placing it in the furnace, the mud on the bottom of the carbonization chamber and on the grinding plate must be cleaned thoroughly. The maintenance methods for the semi-dry spray patching machine are as follows. After each application of repair material, the remaining material in the feed pipe should be promptly cleared away using air, and the spray gun should be rinsed with water to prevent blockages in the pipes. After each application, the remaining material in the hopper and wheel assembly must be removed, as well as any debris from the filter. The air hammer should not be used for cleaning for extended periods of time; it should be placed in an oil bucket every 4–5 minutes to cool down. If it is not used for a long time, the repair applicator should be operated once a month or so to check for any abnormalities. The wheel assembly must be replaced when its thickness is less than 1/3 of its original thickness. Equipment such as the repair applicator and spray gun should be stored in a dry place. Therefore, the working principle of the semi-dry spray repair technique is that the dry spray repair material is humidified in a dry sprayer using compressed air and a mixer, and then transported through nozzles. The spray repair material, containing 10%-12% moisture after mixing, is applied to the damaged area, where it is compacted and smoothed with a trowel to achieve the purpose of repair. Since the dry spray material used in spraying contains about 10%-12% moisture, it eliminates the damage to the furnace wall caused by wet spraying; it requires fewer equipment, results in shorter maintenance times, and has a longer service life, making it particularly suitable for the maintenance of the furnace nozzle area in carbonization chambers. (3) Flame welding repair technique: The working principle of this technique is that propane gas, which serves as the heat source for the flame, and oxygen, which acts as an oxidizing agent, are fed into the welding gun via a controller. From there, they are ejected through the nozzle of the welding gun, forming a nearly cylindrical flame with a diameter of about 150 mm and a length of about 600 mm in front of the nozzle (the flame temperature ranges between 2200 and 2500°C). The powdered repair material is carried by oxygen as a carrier; it is heated to a molten state by the propane-oxygen flame generated at the nozzle of the welding gun, and then blown onto the damaged brick surface whose surface layer has been preheated to a semi-molten state, where it bonds to that surface. It is then compacted and smoothed using a welding gun applicator, thereby repairing the damaged area. Its features include: it does not lower the furnace temperature during repair, does not damage the surface structure of the masonry joints, provides strong adhesion, and the repair layer has excellent wear resistance, thus ensuring durability. Its main equipment is as follows. ①Control box: The function of the control box (see Figure 5-15) is to supply air and water to the equipment, to regulate and control the flow rate and pressure to meet the requirements of the equipment, and at the same time to adjust the flow rate of the spray material. ②The welding gun is used to generate a flame at its tip from oxygen and propane, which are supplied at a certain pressure and flow rate by the control box; this flame then melts the powder that is fed into it, allowing it to be sprayed onto the wall surface that needs repair. There are generally two types of gun tips: circular and square. The length of the gun barrel can be adjusted according to the area to be welded; for 1–2 burners, a length of 2.5 m can be used, while for 3–4 burners, a length of 3.5–4 m is appropriate, as shown in Figures 5–6. ③ Vibration screener: Its function is to assist in operating the welding gun by smoothing out the molten powder that is sprayed onto the furnace wall by the gun. Its length and width are manufactured in the same way as those of the welding torch, and it adopts a hydraulic vibration water-cooling design (see Figure 5-7). ④The air hammer is used to remove the graphite and brick debris from the damaged wall surface prior to welding, thereby improving the quality of the repair; see Figure 5-8. ⑤Oxygen source, propane gas source, water source. For coke oven flame welding equipment, a relatively large amount of oxygen is required; taking an equipment with a processing capacity of 50 Kg/h as an example, the maximum oxygen consumption is 75 m3/h. A flame welding and repair device with a processing capacity of 50 Kg/h requires propane gas at a flow rate of 20 m3/h. Therefore, during operation of the device, it is common to use four 50 Kg liquefied gas cylinders in a group, connected in parallel, so as to make full use of the propane contained in the cylinders. Since flame welding equipment operates in high-temperature environments, the absence of cooling measures will inevitably lead to damage to components such as the seals inside the equipment. Therefore, such equipment must be equipped with a water source that meets the operational requirements; generally, a water storage tank with a capacity of 10 m3 along with a water pump are sufficient to provide cooling through water circulation. Flame repair technology was first introduced from Japan; due to the high temperature of the flame at the outlet of its welding gun, it is suitable for use in areas outside the furnace head for flame repair tasks. The semi-dry spraying repair technology was introduced from Germany and is appropriate for applying repairs to areas such as the furnace head that contain iron components. The semi-dry method eliminates the damage to the furnace walls caused by wet spraying methods, and allows for rapid repair of the furnace head area. Therefore, a complementary use of the two techniques yields better results; employing flame welding and semi-dry spraying techniques for the maintenance of coke ovens will undoubtedly have a positive impact on their longevity.

When can I see the drawings?

Hehe, it’s unlikely that I can make it myself; it’s better to buy a ready-made one. Who can give you the construction drawings? ? ? I originally bought it from the German company Littburg; now it’s produced in China, but I’ve forgotten which specific manufacturer it is. .

Who has pictures of such equipment now?

Hehe, it turns out to be spray painting; I thought it was semi-dry desulfurization~~ My apologies~~