Thread Content
A coke oven is a type of thermal furnace with high investment costs and a complex structure, requiring a service life of generally over 30 years. Since the production of coke ovens is influenced by various factors, the service life of the first generation of coke ovens built in China during the 1960s and 1970s was mostly less than 25 years; only a few steel companies’ coke ovens reached a service life of 30 years. Currently, after undergoing major repairs, these coke ovens are in their second generation of operation and have entered the maintenance or aging phase. These coke ovens are generally furnaces with a carbonization chamber height of 4.3 meters; there are over 70 such ovens in total, and their annual coke production amounts to 28 million tons, accounting for more than one-seventh of the country’s total annual coke output. We should strengthen the thermal maintenance of these coke ovens to meet the needs of the development of ironmaking technology in our country. These coke ovens will need to be in service for at least another 10 to 20 years. Attention should be paid to the role of spray repair technology for coke ovens. Since Baosteel introduced 6-meter coke ovens in the 1980s, there are now nearly 60 such ovens in use in China, most of which have been in operation for over 10 years. In addition, there are nearly 70 large and medium-sized coke ovens under construction in our country, with an annual production capacity of over 30 million tons ； 55 coke ovens are planned to be built, with an annual production capacity of approximately 27 million tons. It is particularly urgent to adopt advanced long-life maintenance techniques for coke ovens in order to carry out effective maintenance and repair on these ovens. In terms of the thermal repair and maintenance techniques for coke ovens, many domestic steel companies have, through experimentation, developed methods such as dry spray patching, wet spray patching, flame welding, and semi-dry spray patching. Through technological innovation, these methods have helped to curb the aging of coke ovens and extend their service life. During coal charging and coke extraction in the coke oven, the brickwork of the carbonization chamber is subjected to mechanical forces resulting from coke pushing, stresses caused by periodic and drastic changes in oven temperature, as well as chemical reactions between the silica bricks at high temperatures and external substances. As a result of these normal or abnormal factors, defects such as peeling, cracking, dents, and missing corners occur in certain sections of the brickwork, especially in the front part of the carbonization chamber. This inevitable change begins as soon as coke is produced in the coke oven, and the degree of damage increases as the oven’s operating age grows; proper maintenance can slow down the rate of this damage. Under normal circumstances, when the furnace has been in use for over 10 years, a modified layer forms on the surface of the furnace wall bricks. As the furnace’s operating time increases, the degree of this modification and erosion worsens, leading to severe damage to the brick wall. Damage to the furnace wall usually starts at the furnace tip and then moves toward the center. To ensure stable production and a long service life for coke ovens, it is essential to carry out preventive shot blasting on the oven head section. If the inherent construction quality of the coke oven is the foundation for its long service life, then subsequent thermal maintenance is what ensures that longevity; it helps to maintain the tightness of the masonry in all parts of the oven. The uniqueness of damage to coke oven masonry and the complexity of its repair present new challenges in terms of thermal maintenance techniques for coke production workers in our country. This forces us to continuously develop new technologies and explore the principles behind shot blasting repairs, in order to slow down the aging process of the oven structures and extend their lifespan.