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Transfer the content of ryn (113866): Characteristics of several typical dry quenching processes and the current status of dry quenching technology in China!   Part 1: A brief introduction to the characteristics of several typical dry quenching processes for coke! I. Characteristics of the dry quenching technology developed by German company ISOA The features of the dry quenching technology designed by the German company TSOA are as follows: (1) The dry quenching furnace is designed to be square in shape ；      (2) No primary dust collector is installed between the dry quenching furnace and the boiler ；      (3) The circulating fan uses variable frequency speed control ；      (4) Grid-type swinging coking discharge is adopted to ensure uniform coking discharge temperature.        The square dry quenching furnace designed by TSOA Company tapers to 25% of its original cross-section between the pre-storage section and the cooling section; the pre-storage section is supported by a steel structure, which is a significant difference from circular dry quenching furnaces. Due to the narrowing between the pre-storage section and the cooling section, the coke in the cooling section takes on a conical shape, creating large amounts of empty space; as a result, the velocity of the circulating gas decreases at this location, and larger coke particles settle within the quenching chamber. According to TSOA, the largest coke particles carried away by the circulating gas from the dry quenching furnace are 0.5–1 mm. This is also an important reason why TSOA’s design for dry quenching of coke eliminates the need for a dust collector between the dry quenching furnace and the boiler.        The lower part of the square-shaped dry quenching furnace is divided into 12 compartments, each equipped with a hydraulically driven swing-type coke discharge mechanism for discharging the cooled coke from each compartment. Thermocouples are installed to monitor the coke temperature; when the temperature in a particular compartment drops to the permissible level for coke discharge, the shutter of the corresponding swing-type discharge mechanism opens. This ensures uniformity in the coke discharge temperature.        TSOA Company installs cooling walls in the upper section of the cooling zone of the dry quenching furnace. In the dry quenching furnace, red coke is cooled not only by the circulating cooling gas, but also 30% of its heat is absorbed by the cold water in the cooling walls; in fact, the cooling walls can be regarded as part of the boiler. The advantage of using cooling walls is that it allows for a reduction in the amount of circulating cooling gas, by about 20%, which in turn reduces the power consumption of the circulation fans and thus lowers operating costs ； The downside is that it increases the amount of maintenance required; if the water inside the cooling wall tubes is not controlled properly, it can leak into the dry quenching furnace, causing significant damage to the dry quenching unit and even leading to accidents. Of course, the dry quenching furnaces designed by TSOA can also be constructed without cooling walls. II. Characteristics of Nippon Steel’s dry quenching technology for coke The characteristics of the dry quenching technology designed by Nippon Steel are as follows: (1) The dry quenching furnace is designed to be circular in shape ；        (2) The loading device is equipped with a hopper ；        (3) Use a rotary seal valve for continuous coking discharge ；        (4) CO in the fully burned cycle gas ；        (5) The circulating fan has no speed control ；        (6) Rotating coke oven is used for coke charging.        The charging device equipped with a material hopper helps to ensure a uniform distribution of red coke within the dry quenching furnace, which in turn facilitates uniform cooling of the coke. It also allows for a reduction in the volume of circulating air, thereby lowering the power consumption of the circulation fans ； The coking discharge device uses a rotary seal valve in place of the previous intermittent type, which can reduce the height of the dry quenching system by about 4 meters, thereby lowering construction costs; it also enables true continuous coking discharge.        The dry quenching process designed by Nippon Steel uses a method to completely burn H2 and CO in the circulating gas, with any excess circulating gas being able to be discharged directly. According to Nippon Steel, the burn loss rate for incompletely burned coke is 6–7 kg/t, while that for completely burned coke is 9.9 kg/t. However, from a theoretical perspective, among the coke that suffers burn loss, 20% has a particle size of 20 mm or more, and 80% has a particle size of less than 20 mm; thus, in reality, most of it is fine coke. Measurements conducted by Nippon Steel on the dry quenching of coke in coke ovens No. 3 and No. 4 at Guangyuan showed that 82.1% of the coke particles with a size of 25 mm or less were subject to burn loss ； When the burned coke accounts for 1% of the total coke loaded, the depth of surface burn on the large pieces of coke is only 22 mm.        Between the inlet of the circulating gas pipeline to the dry quenching furnace and the outlet of the annular flue, there is a bypass that primarily serves to reduce the temperature of the circulating gas entering the boiler, thereby preventing any adverse effects on the boiler due to excessively high temperatures of the circulating gas. However, this bypass is not always open. Nippon Steel believes that the recirculation fan does not require speed control; as long as the time during which coke supply is halted does not exceed the designed duration of the storage section, its rotational speed can remain unchanged. Therefore, for the recirculation fan, only dampers are designed to perform coarse adjustment of the air volume.        Nippon Steel believes that a baffle wall is not necessary for the primary dust collector, which is related to its design for dry quenching of coke based on complete combustion ； Furthermore, Nippon Steel believes that without a baffle wall in the primary dust collector, particles larger than 1 mm can settle due to their own gravity, whereas it is only particles larger than 1 mm that can have an adverse effect on the boiler. For a dust collector without retaining walls, the silo can be much smaller, which reduces construction costs; moreover, maintenance is also easier. However, the vast majority of primary dust collectors for dry quenching of coke designed by Nippon Steel are equipped with baffle walls. III. Technical characteristics of dry quenching for Cokes Ovens No. 7 and No. 8 at Wuhan Iron and Steel Group The quenching process for Cokes Ovens No. 7 and No. 8 at Wuhan Iron and Steel Group utilizes technology from Nippon Steel of Japan, with certain improvements made; it represents a relatively advanced level at present. Its technical characteristics are as follows: (1) The dry quenching furnace is designed to be circular in shape ；       (2) The use of a circular rotating coke oven facilitates uniform coke charging ；       (3) The loading device is equipped with an advanced cross-shaped hopper, which helps to ensure even coke loading and protects the air cap of the dry quenching furnace ；       (4) A continuous coking discharge device equipped with a rotary seal valve facilitates uniform coking discharge ；       (5) The circulating fan uses variable frequency speed control, which facilitates more precise adjustment of the circulating gas flow rate ；       (6) The secondary dust collector uses a multi-tube cyclone dust collector, which helps to improve the dust removal efficiency of the circulating gas ；       (7) A feedwater preheater is designed to further cool the circulating gas entering the dry quenching furnace ；       (8) Completely burn H and CO in the cycle gas.        The circular rotating coke drum makes full use of the drum’s volume, which facilitates a uniform distribution of coke within it. As a result, the weight of the coke drum can be reduced, thereby lowering the power required by the hoist. Additionally, the lifespan of the lining material in the coke drum can also be extended. The loading device equipped with an advanced cross-shaped material hopper facilitates a more even distribution of red coke inside the dry quenching furnace. Both this loading device and the circular rotating coke tank help to reduce the volume of circulating air, thereby lowering the power consumption of the circulation fans.        The continuous coke discharge device equipped with airtight rotary seal valves can **reduce the leakage of circulating gas** ； Depending on the level of material in the pre-storage section of the dry quenching furnace, the amount of coke discharged can be controlled with great precision using a vibrating feeder, thereby allowing the cooled coke to be discharged in a quantitative and continuous manner ； With a variable-frequency speed control circulator fan, the flow rate of the circulating gas can also be adjusted with high precision. A consistently precise coke discharge amount, combined with an accurate circulating gas flow rate, contributes to stabilizing the temperature at the boiler inlet and ensuring stable operation of the dry quenching boiler.        A primary dust collector equipped with a retaining wall can remove coarse coke particles from the circulating gas, ensuring that the concentration of coke particles in the gas entering the boiler remains between 10 and 12 g/m3, with the particle diameter of these coke particles being less than 1 mm; this reduces wear on the heat transfer tubes in the boiler. At the bottom of the dust collector, there are 4 water-cooled sleeves used for cooling and removing coke powder. The circulating gas exiting the boiler passes through an advanced multi-tube cyclone dust collector, which removes most of the fine particulate coke dust; as a result, the mass concentration of coke dust in the circulating gas can be reduced to less than 1 g/m³, thereby eliminating any risk to the circulating fan. Compared to multi-stage cyclone dust collectors, multi-tube cyclone dust collectors offer better dust removal performance, require less space, use less tubing and steel structures, thereby reducing construction costs.        The feedwater preheater consists, from top to bottom, of an upper shell, an upper section, a lower section, and a lower shell, among which the upper section and the lower section are shell-and-tube heat exchangers. The circulating gas, after being pressurized by the circulation fan, enters the feedwater preheater horizontally from the lower shell. It undergoes heat exchange in the lower and upper shell-and-tube heat exchangers, and then is discharged from the upper shell of the feedwater preheater. The feedwater preheater serves two purposes: first, it further reduces the temperature of the circulating gas entering the dry quenching furnace, lowering it from around 180°C at the outlet of the circulation fan to about 130°C, thereby improving the cooling effect on the coke and reducing the flow rate of the circulating gas ； Secondly, the heat from the recycled gas is further utilized to reduce the amount of steam required by the deaerator.        The advantage of using the method that burns off H2 and CO in the cycle gas is that the excess cycle gas can be discharged directly ； Second, it can raise the inlet temperature of the recirculated gas into the boiler, thereby increasing the boiler’s steam output ； Third, it reduces the corrosion of the boiler caused by the circulating gas. Part Two: The current status of dry quenching technology in China!        Since the early 1980s, when Baosteel’s first phase introduced dry quenching technology from Japan, six plants in China have now put such systems into operation. There are also certain differences in the way these systems are used across various plants. The status of dry quenching installations in China is as follows: 1. Baosteel’s dry quenching system – To support its 12×50-hole (6 m) coke ovens, Baosteel built 12 sets of dry quenching units with a capacity of 75 t/h each; these units can process 5.1 million tons of coke per year. The construction was carried out in three phases. The first phase of the 4×75 t/h dry quenching unit was put into operation in May 1985, while the second and third phases were commissioned in June 1991 and December 1997 respectively. The first phase of the dry quenching unit was fully imported from Japan ； The second-phase dry quenching unit was developed based on the experience gained from the first phase, and it was primarily designed and constructed in China. The proportion of domestically produced equipment accounts for 80% of the total weight of the equipment, with some key components being imported from Japan ； In Phase 3, apart from a very small number of key components imported from Japan, the vast majority of equipment has been domestically produced, with a localization rate exceeding 90%. Baosteel uses only dry quenching for coke, without wet quenching as a backup, and adopts a production mode of \"three in operation and one in standby\". 2. Dry quenching of coke at Pudong Gas Plant: To support the quenching process of coke ovens that produce 560,000 tons of coke per year, Pudong Gas Plant introduced a set of dry quenching equipment with a capacity of 2×70 t/h from the Soviet Union in 1984. The State Design Institute for Coking in the Soviet Union was responsible for the core design of this entire dry quenching system; Anshan Coking and Refractory Institute and Shanghai Chemical Research Institute were involved in the supplementary design aspects. Anshan Coking and Refractory Institute took on the overall design and construction responsibility for this dry quenching project. Construction began in December 1991, and the project was completed and put into operation in December 1994. The entire set of dry quenching equipment for coking is imported from Russia, with wet quenching retained as a backup option. 3. Dry quenching of coke at Jigang: To support the quenching process of the coke ovens that produce 1.1 million tons of coke per year, Jigang introduced dry quenching equipment with a capacity of 2×70 t/h from Russia in 1994; this equipment was designed jointly by the Russian State Design Institute for Coking and Jigang’s own design institute. Regarding the equipment, a combination of partial import and cooperative manufacturing was adopted; the project commenced in 1996 and was completed and put into operation in March 1999. After commissioning, it was found that the Russian technology lacked reliability and that it took a long time to reach full production capacity. Like the dry quenching unit at the Pudong Gas Plant, this device does not have a high level of automation, and wet quenching is still used as a backup option. 4. Shougang Dry Quenching of Coke: Shougang’s first-phase dry quenching plant with a capacity of 1×65 t/h was built as part of a green assistance program provided by Japan; the main equipment was supplied by Japan, while the auxiliary equipment was purchased by Shougang itself. The design of the facility was jointly carried out by Nippon Steel and Shougang Design Institute. Construction began in 1999, and it was put into operation in January 2001. Since its commissioning, Shougang’s dry quenching unit has operated reliably, with an ideal level of automated control and excellent environmental protection performance. Shougang also retains wet quenching as a backup. 5. Dry quenching of coke at Wuhan Iron and Steel Group: Wuhan Iron and Steel Group’s No. 7 and No. 8 coke ovens are 2×55-chamber 6 m coke ovens, and the design capacity of their dry quenching system is 1×140 t/h. The core design of this system was developed by Japan, while the adaptation design was carried out by Anshan Coke and Refractory Research Institute. This project is a **absorption and digestion project undertaken by the National Development and Reform Commission; it is currently the dry quenching coke plant with the largest single-unit processing capacity in China. The key equipment for dry quenching of coke was imported from Japan; some of the equipment was designed and supervised by Japanese parties while manufactured by domestic manufacturers. The automatic control system for dry quenching of coke was designed by Wuhan Iron and Steel Group itself. Construction began in October 2002, the facility was completed and put into operation in December 2003, and it reached full capacity by June 2004. The dry quenching of coke in Wuhan Iron and Steel Company’s No. 7 and No. 8 coke ovens still retains wet quenching as a backup option. 6. Dry quenching of coke at MaSteel: MaSteel’s No. 5 and No. 6 coke ovens are 2×50-chamber 6 m coke ovens, equipped with a dry quenching system capable of handling 1×125 t/h of coke. This system was constructed under the overall supervision of Anshan Coke and Refractory Research Institute; some of the key equipment was imported from Japan, Germany, and the United States, while the remaining equipment was manufactured domestically. It is currently the dry quenching system in China that makes use of the most domestically produced components. It came online in April 2004, with a wet quenching method also available as a backup option. With the continuous improvement of environmental protection regulations and the rising awareness of environmental protection among the public, it has become imperative to develop dry quenching technology; all steel mills that construct coke ovens with a diameter of over 4.3 meters must install corresponding dry quenching systems.