What does thermal engineering involve in coke oven construction?
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What does thermal engineering involve in coke oven construction?
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Hot-state engineering of coke ovens: Hot-state engineering refers to those tasks that must be carried out only after the expansion of the oven body has essentially come to an end during the baking phase (with a few exceptions). Most of it needs to be completed before construction starts, while a small portion can be done after it begins. Thermal engineering projects have tight schedules and large volumes of work, which have a significant impact on the quality and service life of coke ovens. When carrying out hot-state engineering, no tasks must be omitted, and no formalities must be performed superficially; it is necessary to proceed with care and ensure both quality and quantity. I. Hot-state Project Projects Table 1: List of Hot-state Projects Serial Number Project Execution Time (Chamber Temperature) Remarks 1 Sealing of cracks on the furnace top Sealed with asbestos rope 2 Demolition of temporary shed 200–250°C; can be delayed during the rainy season 3 Application of waterproof layer on the top surface of the protective plate Before demolishing the shed 4 Adjustment of the switchgear 500°C 5 Sealing of the socket joint of the small flue After 600°C, remove the temporary asbestos rope, reinsert it, and fill the gaps 6 Filling of expansion joints on the front side of the inclined duct and finishing of mortar joints 600°C; expansion joints filled with asbestos rope dipped in mortar 7 Filling of 30mm expansion joints 600°C; filled with loose asbestos rope dipped in mortar 8 Finishing of mortar joints in the walls of the heat storage chamber 750°C; before applying the insulation layer to the walls 9 Sealing of connections between the switchgear and the flue pipes with asbestos rope 500°C; after adjusting the switchgear 10 Grouting of brick gas flues (for upward-type coke ovens) 600°C 11 Sealing of the socket joint of the bridge pipe 650°C 12 Connection of the air intake pipes and tar boxes 650°C 13 Lubrication of points in the gas and exhaust systems 600°C 14 Connection of ladders to the gas collection panel 650°C 15 Cutting off the set screws of the protective plate 650°C; before constructing the small furnace head 16 Connection of ammonia branch pipes (around the rising pipe) 650°C 17 Connection of steam pipes, industrial water pipes, and compressed air pipes (around the rising pipe) 650°C 18 Trial operation of the switching system 550°C 19 Installation and adjustment of the tracks for the coal loading vehicle 650°C; tracks fixed at 700°C 20 Installation and adjustment of the wiring racks and wires for the coal loading vehicle 650°C 21 Fixing of safety railings on the furnace top 650°C 22 Connecting the tracks of the coal loading vehicle to the end platform 700°C 23 Connecting the tracks of the coke pushing vehicle to the end platform 700°C; pouring concrete at the remaining sections 24 Tightening of flanges on small gas branch pipes (vertical pipes) 750°C 25 Fixing bolts between the gas collection bracket and the furnace column 750°C 26 Lowering and positioning of crossbars 750°C; monitoring and adjusting spring load 27 Removal of furnace drying equipment after switching to normal heating 28 Removal of temporary testing platforms 800°C 29 Grouting of gaps around the furnace shoulder and filling of the grinding plates Before grouting the protective plate 30 Tightening of bolts connecting the protective plate to the furnace frame 800°C; tightening evenly 31 Filling of gaps at the bottom of the protective plate Before grouting the protective plate 32 Packing of gaps at the upper joints of the protective plate with asbestos rope Before grouting the protective plate 33 Grouting of the protective plate 750°C; grouting in segments 34 Cleaning of the blade cover on the furnace frame 800°C 35 Reconstructing and grouting the small furnace head 850°C; carried out after grouting the protective plate and finishing the gaps on the front side of the furnace top 36 Grouting and filling of cracks on the furnace top before filling the insulation material in the strip grooves 850°C; cleaning first 37 Finishing of the furnace top surface 900°C 38 Filling of insulation material in strip grooves and laying bricks 850°C; done in segments, while monitoring and adjusting spring load 39 Fixing of drainage pipes on the control panel 800°C 40 Installation of baffles for the small furnace head 900°C; after reconstructing the small furnace head 41 Adjustment of the blade edges of the furnace door before coal loading 42 Trial operation of the furnace door repair station 800°C 43 Adjustment and fixation of tracks for the coke pushing vehicle 750°C 44 Adjustment of wiring racks and safety railings for each vehicle 850°C; carried out in conjunction with trial operations of each vehicle 45 Calibration of the coal tower scale 800°C 46 Load-testing of the switching gear and switching transmission system 700°C 47 Insulation of the switchgear After switching to normal heating or after operation starts 48 Handling of remaining sections on the front side of the furnace end wall After switching to normal heating or after operation starts 49 Reconstruction of the masonry surface on the furnace end wall After switching to normal heating 50 Laying foundation bricks before removing the fire bed
II. Grouting of the Protective Plate (Furnace Frame) and Sealing of Gaps Around the Furnace Shoulder The quality of grouting of the protective plate (furnace frame) has a significant impact on the lifespan of the coke oven. During operation, the connection between the protective plate (furnace frame) and the furnace body is mainly sealed using mud. In coke ovens equipped with small protective plates, if the quality of the grouting is poor, it can lead to damage to the furnace columns and frames, thereby shortening the lifespan of the coke oven and preventing it from operating at full capacity. The following tasks must be completed before grouting: (1) The elevation of the grinding plate has been verified to be satisfactory. (2) All the connecting bolts between the furnace frame and the protective plate have been adjusted. (3) Sealing of the gaps at the upper joint of the protective plate and between the lower part of the protective plate and the masonry protrusion is complete. (4) All gaps at the furnace shoulder should be properly sealed. (5) Remove the temporarily built small burner or waterproof layer at the top of the combustion chamber. To prevent a sharp drop in the temperature of the burner masonry and avoid mortar leakage, it is generally poured in 2 to 3 stages, with an interval of 1.5 to 2 hours between each pouring. During grouting, the fire viewing cover of the adjacent combustion chamber burner should be opened to check whether slurry is leaking into the vertical flue; if it does leak in, grouting must be stopped immediately, and work can resume only after the slurry has solidified. The mud composition used for grouting is: 1000 kg of low-temperature silica cement plus 16 kg of water glass (with a Na2O content of 10%–14%), with a density ranging from 1.7 to 1.8 g/cm3. When using waste fireclay from furnace construction, impurities must be screened out. The material used to fill the gap between the sealing guard plate and the furnace shoulder consists of 60% low-temperature silica mortar, 40% concentrate powder, along with 12%–16% water glass. III. Filling in the longitudinal and transverse strips: For insulation using transverse strips and filling, first clean the grooves for these strips by using a vacuum cleaner or compressed air, and fill any cracks in those grooves with thin mud. Remove the wooden blocks that serve as supports, then insulate the area using thermal insulation bricks before covering it with bricks. Since the insertion of insulating material into the cross-brace grooves causes the temperature of the cross-braces to rise sharply, leading to their expansion and a significant decrease in the spring load, which in turn puts strain on the compression springs, the filling is generally carried out in 3 stages: first, the side facing the coke oven (the outside of the coal car tracks) is filled, with the material being installed along the longitudinal direction of the coke oven; next, the grooves between the coal car tracks are filled; finally, the grooves on the machine side are filled. Bricks can be laid on top of the tie trench while filling it. In the later stages of furnace heating, the pressure in the carbonization chamber is very high, causing many cracks to appear in the furnace roof. To prevent the tie rods from being damaged, the grooves for these tie rods at the coal loading holes and rising pipe holes are not filled yet; they will be filled after the coke oven is loaded with coal.
II. Grouting of the Protective Plate (Furnace Frame) and Sealing of Gaps Around the Furnace Shoulder The quality of grouting of the protective plate (furnace frame) has a significant impact on the lifespan of the coke oven. During operation, the connection between the protective plate (furnace frame) and the furnace body is mainly sealed using mud. In coke ovens equipped with small protective plates, if the quality of the grouting is poor, it can lead to damage to the furnace columns and frames, thereby shortening the lifespan of the coke oven and preventing it from operating at full capacity. The following tasks must be completed before grouting: (1) The elevation of the grinding plate has been verified to be satisfactory. (2) All the connecting bolts between the furnace frame and the protective plate have been adjusted. (3) Sealing of the gaps at the upper joint of the protective plate and between the lower part of the protective plate and the masonry protrusion is complete. (4) All gaps at the furnace shoulder should be properly sealed. (5) Remove the temporarily built small burner or waterproof layer at the top of the combustion chamber. To prevent a sharp drop in the temperature of the burner masonry and avoid mortar leakage, it is generally poured in 2 to 3 stages, with an interval of 1.5 to 2 hours between each pouring. During grouting, the fire viewing cover of the adjacent combustion chamber burner should be opened to check whether slurry is leaking into the vertical flue; if it does leak in, grouting must be stopped immediately, and work can resume only after the slurry has solidified. The mud composition used for grouting is: 1000 kg of low-temperature silica cement plus 16 kg of water glass (with a Na2O content of 10%–14%), with a density ranging from 1.7 to 1.8 g/cm3. When using waste fireclay from furnace construction, impurities must be screened out. The material used to fill the gap between the sealing guard plate and the furnace shoulder consists of 60% low-temperature silica mortar, 40% concentrate powder, along with 12%–16% water glass. III. Filling in the longitudinal and transverse strips: For insulation using transverse strips and filling, first clean the grooves for these strips by using a vacuum cleaner or compressed air, and fill any cracks in those grooves with thin mud. Remove the wooden blocks that serve as supports, then insulate the area using thermal insulation bricks before covering it with bricks. Since the insertion of insulating material into the cross-brace grooves causes the temperature of the cross-braces to rise sharply, leading to their expansion and a significant decrease in the spring load, which in turn puts strain on the compression springs, the filling is generally carried out in 3 stages: first, the side facing the coke oven (the outside of the coal car tracks) is filled, with the material being installed along the longitudinal direction of the coke oven; next, the grooves between the coal car tracks are filled; finally, the grooves on the machine side are filled. Bricks can be laid on top of the tie trench while filling it. In the later stages of furnace heating, the pressure in the carbonization chamber is very high, causing many cracks to appear in the furnace roof. To prevent the tie rods from being damaged, the grooves for these tie rods at the coal loading holes and rising pipe holes are not filled yet; they will be filled after the coke oven is loaded with coal.