Structure and features of German 7.63m coke ovens
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Structure and features of the coke oven: a) The 7.63m coke oven features dual flue channels, staged air supply for heating, and exhaust gas recycling; coke oven gas is injected from below, while low-calorific-value mixed gas and air are introduced from the sides. It is a super-large coke oven with regenerative chambers and single-sided flues. This coke oven features an advanced and robust structure, strong functionality, uniform heating, high thermal efficiency, as well as energy-saving and environmental protection properties. b) In the segmented regenerative chamber, each vertical flue corresponds to one segment of the regenerative chamber, forming one heating unit. When heating with coke oven gas, the gas is regulated in the basement using nozzles equipped with orifice plates; orifice plate regulation is convenient and accurate ； The air is regulated by the metal control plate at the top of the small flue. When heating with low-calorific-value mixed gas, both the gas and air are regulated by metal adjustment plates at the top of the small flue, so as to ensure a reasonable and uniform distribution of the heating gas and air along the length of the regenerative chamber. c) The main walls of the regenerator chamber have a tight structure for both the primary walls and partition walls; they are constructed using special-shaped bricks laid in a staggered pattern, which ensures that there is no leakage between different sections of the masonry. The lower parts of the main walls and single walls are constructed with semi-silica bricks, while the upper parts are built with silica bricks; a sliding joint is provided between the semi-silica brick masonry and the silica brick masonry. d) The small flue in the regenerator uses a single-sided flue. e) Segmented heating complicates the chute structure, resulting in a variety of brick shapes. However, the absence of expansion joints in the tunnel of the inclined shaft ensures its tightness, preventing high-temperature accidents in the upper part of the inclined shaft area. f) The combustion chamber consists of 36 dual flues, totaling 18 pairs. Air is supplied in 3 stages to achieve staged combustion ； Circulation holes are also provided at the lower part between each pair of flue partition walls to draw in the exhaust gases from the descending flues into the combustible gases in the ascending flues; these two methods are used to lengthen the flame and achieve uniform heating in all directions. When heated with a low-calorific-value mixed gas of blast furnace gas and coke oven gas, air is injected through the outlets at the bottom of the combustion chamber via inclined channels, as well as through the outlet partitions in the vertical flues located at 1/3 and 2/3 of the distance from the bottom of the combustion chamber; this air combines with the low-calorific-value mixed gas ejected from another outlet in the inclined channel at the bottom of the combustion chamber to achieve three-point combustion heating ； When the coke oven is heated solely with coke oven gas, the mixed gas channel also carries air, just like the air channel; the air is injected through outlets located at the bottom of the combustion chamber, at 1/3 and 2/3 of the distance from the bottom of the chamber, via the vertical flue partition outlets. Coke oven gas is ejected from the gas nozzles at the bottom of the combustion chamber, enabling three-point combustion for heating. Thanks to three-stage combustion heating and exhaust gas recirculation, the furnace achieves uniform heating from top to bottom, and the nitrogen oxide content in the exhaust gases is low, allowing it to meet advanced environmental standards. g) The furnace top is equipped with 4 coal loading ports and 1 water-sealed rising pipe.
Special features of technical management for large coke ovens 1 Analysis of the advantages of large coke ovens 1) High labor productivity: The four major machines used in large coke ovens are equipped with an automatic positioning interlock system, and the PLCs are powered by UPS for precise positioning. The operation modes of these machines in 7.63m coke ovens allow for fully automatic, semi-automatic, interlocked, and manual operation. Each carbonization chamber has a self-regulation function for pressure, resulting in high labor productivity. In large coke ovens, as the height and width of the carbonization chamber increase, the coke production also increases. For top-charging coke ovens of 4.3m, 6m, 7m, and 7.63m in length, the coke output per carbonization chamber varies. The amount of coke produced per chamber in a 7m top-charging oven is 2.05–2.37 times that of a 4.3m top-charging oven, and 1.28–1.49 times that of a 6m oven ； The amount of coke pushed out per hole in a 7.63m coke oven is 2.04 times that of a 6m top-loaded coke oven, and 1.38–1.59 times that of a 7m coke oven. The amount of coke produced per hole in a 6.25m rammed coke oven is 1.20 times that of a 5.5m rammed coke oven. 2) With a high level of environmental protection, large coke ovens require fewer furnace turnovers per unit of production, resulting in less intermittent pollution from coal loading and coke pushing. Taking a coking plant with an annual coke production of 2 million tons as an example: for coke ovens with heights of 7.63m, 7m, 6m, and 4.3m, the number of times coke is pushed out per day is 113, 172, 255, and 357 respectively. The fewer times the coke is taken out of the oven, the less there is in terms of intermittent pollutant emissions associated with coal loading and coke pushing. Environmental protection measures for leakage points such as furnace doors, rise pipes, and coal loading ports are well implemented; there are few leakage points, resulting in reduced intermittent pollution. Taking a coke oven with an annual production capacity of 1.1 million tons as an example, those with a carbonization chamber height of 7 meters have 23.6% fewer leakage points compared to ovens with a 6-meter height; the length of the sealing surfaces is reduced by 8.5%, and the number of times each leakage point needs to be opened per day is decreased by 31%. This **reduces the emission of harmful gases and improves the operating conditions in coke production. The JNX3‑70 type coke oven adopts measures such as increasing the exhaust gas circulation rate, installing high and low nozzles for coke oven gas, and providing air in stages, to reduce NOX generation; the NOX concentration in the flue gas is less than 500 mg/m3. 2 Differences in the structure of large-scale coke ovens: China has become a global leader in coke-making technology, and currently possesses almost all types of top-loading coke ovens available in the world. For top-mounted coke ovens, the average width of the carbonization chamber in 4.3m coke ovens is 0.407m, while that in 6m coke ovens is 0.45m, representing an increase of 10.57% in width ； The average width of the carbonization chamber in 7m coke ovens is 0.50m, representing an increase of 22.85% in width ； For the 7.63m coke ovens, the average width of the carbonization chamber is 0.60m, representing an increase of 47.42% in width. In other words, compared to the 4.3m coke oven, the width of the carbonization chamber in the 7.63m coke oven is nearly doubled, its height has increased by 39.76%, and its effective volume is 3.53 times that of the 4.3m model. A modern large-scale coke oven is a thermical furnace with a complex structure. There are significant differences in the structural design between 7.63m coke ovens and 6m coke ovens; the main difference lies in the fact that in 7.63m coke ovens, the lean gas and air are introduced from the sides, while the regenerator is divided into sections and there are smoke channels on one side only ； When heating with low-calorific-value mixed gas, both the gas and air are regulated using metal injection plates at the top of the small flue ； Unilateral small flue ； Air is supplied in 3 stages for staged combustion, and the coke pushing operation in the coke oven follows a 2-1 sequence. Increasing the coal loading in large coke ovens does not simply mean raising the furnace temperature; since the shrinkage rate of coke is related to the coking time and coking rate, these factors also change, which requires the use of more of the scarce primary coking coal. The Anshan Thermal Energy Research Institute of China Iron and Steel Group and Wuhan Iron and Steel Group conducted studies on the impact of the charging chamber width on the coal, coke, and coke pushing process used in furnace charging. Previous coal blending theories are no longer applicable; as the charging chamber width changes, the coal blending composition must be adjusted accordingly. 3 The complexity of large-scale coke ovens: As coke ovens become larger, the stress conditions on their brick structures become more complex. The process of pushing coals through the oven generates mechanical vibrations on the oven walls, as well as thermal stresses within the oven structure. This imposes higher demands on the material quality of the three key components used to protect the oven, their resistance to thermal changes, as well as the effectiveness of the protection they provide and the rationality of its distribution. The coke oven door is the most important sealing device in the carbonization chamber of a coke oven, and its sealing performance directly affects the continuous emission of dust from the coke oven. As coke ovens become larger, the deformation of the oven doors themselves increases significantly, and the pressure of the gas inside the oven rises, **increasing the difficulty of sealing the oven doors. The material and structure of coke oven doors must be optimized, especially for 7.63m and 7m top-mounted coke ovens as well as 6.25m rammed coke ovens; the strength, stiffness, and degree of deformation of key components such as the door brick grooves, web members, and edge sections must exhibit the optimal structural characteristics in high-temperature environments. The production process of large-scale coke ovens is highly intensive, and the operation requires precision and reliability; therefore, sophisticated automation systems as well as high-quality hardware equipment are necessary.
The 7.63-meter large-volume ramming coke oven is the most advanced type of coke oven in the world, and its design and construction have previously been dominated by foreign countries. China Pingmei Shenma Group pioneered the development of a complete set of technologies and equipment for 7.63-meter-large-volume ramming coke ovens, and it took only 15 months to build and put them into operation at Shoushan Chemical Company, which is at least 3 months shorter than the construction time for coke ovens of the same type. A 110 kV substation is constructed alongside the large-capacity coke ovens; the transmission lines total 16.4 kilometers in length, with 68 tower bases in total. This project affects 4 towns and 18 rural villages, making coordination a significant challenge. Shoushan Chemical Company was built and put into operation in just 165 days, creating a miracle by being the fastest in the construction of projects of its kind.