【Q&A on the Production Operations of Haichuan Coke Ovens】9. What are the reasons for holes forming in the carbonization chamber, and how can these holes in the furnace wall be repaired?

Thread Content

The 25th National \"Safety Production Month\" in 2026: Everyone talks about safety, everyone knows how to handle emergencies; identifying and addressing risks and hazards. -------------------------------------------------- 9. What are the reasons for holes forming in the carbonization chamber, and how can these holes in the furnace walls be repaired? Answer: The walls of the carbonization chamber, especially those in the area of the furnace head, are gradually damaged over time due to mechanical and thermal stresses during the production process. In newly built coke ovens, cracks and slight erosion begin to appear at the head of the carbonization chamber a few years after they come online. Under the combined effect of the following factors, the cracks and erosion further expand until holes form in the furnace wall. (1) Ammonia solution splashing into the bridge tube, leaks in the vapor rising tube, or rainwater infiltration cause the furnace wall to become wet. (2) The maximum stress generated during coke pushing further expands the cracks at the furnace front. (3) Secondary burning often occurs, causing damage to the burner area. (4) After erosion of the furnace wall, wet repair methods are used, which causes the furnace wall bricks to become undercooled and crack; after the material deposition period, the repair material bonds to the furnace wall bricks and then falls off, resulting in new damage. (5) The use of the removal method to eliminate graphite results in the furnace wall lining being removed along with the graphite, causing the furnace wall to gradually thin out. (6) Operational errors with the pusher rod can cause damage to the furnace wall; for example, a deformed pusher rod, or a graphite scraper installed at the end of the pusher rod that is not adjusted properly and thus damages the furnace wall. When bricks fall off or holes appear on the walls of the carbonization chamber, since the area damaged is small (about the size of 1–2 bricks), the repair time is short; the filling method or welding method can be used. Otherwise, the patching method should be employed. Laying method: After coke pushing, once the temperatures in the combustion chambers on both sides of the empty furnace drop to around 600°C, one furnace door and one coal loading port cover are opened. The operator, wearing aluminum-plated clothing and heat-resistant gear, quickly enters the furnace to measure the dimensions of the cavity. Bricks that have been preheated are then cut to fit those dimensions; after applying mortar to them, they are placed inside the furnace to fill the cavity. Next, seal the joints, close the furnace door, then raise the temperature and start operation. After the coke in the preheating carbonization chamber is pushed out, the operator stands at the furnace door or outside the coal loading port and uses a trowel to remove graphite and debris from inside the cavity. Bricks that have been preheated are then shaped according to the dimensions and shape of the cavity. These bricks, with mortar applied to them, are held by supports and transported to the side of the cavity using a lift or steel frame, after which they are pushed into the cavity using a long-handled trowel. Next, use a sprayer to seal the brick joints, remove the brick debris and ash that have fallen to the bottom of the furnace, take down the steel frame or ladder, and then load coal after preheating for 20 minutes. Since this method can be carried out without the need to lower the furnace temperature, it causes less damage to the furnace walls. However, as it involves remote operation outside the furnace, it is difficult to ensure the quality of repairs, and the operation itself is complicated. Caves can also be repaired using the adiabatic box method: first, the furnace temperature is reduced to 500–600°C, and an air-cooled adiabatic box is inserted into the evacuated carbonized chamber. The box frame is made of angle steel and round steel, and is fully covered on the outside with 25mm aluminum-silicon fiber board. Thermal repair technicians enter the box, remove the movable panels from the area to be repaired, and carry out the repairs through the opening. Welding repair method: Before welding repair, use a long-handled support to push the pre-processed and preheated bricks into the hole, and then follow the welding repair procedure to weld the joints between the new and old bricks.