Is there any fire fall management in coking plants?

Baosteel is using it, but it’s actually Nippon Steel’s fire adjustment method.

It is a result-oriented management method. 1. Determine the installation time through observation of fire fall observation holes. 2. At the same time, combined with the online measurement of the raw gas temperature at the bridge pipe, when it rises sharply and suddenly drops by 50 degrees, it is considered to be the moment when the furnace fire falls. 3. Choose a lottery number for each class to measure the fire temperature.

Our unit does not use fire fall management methods to manage coke oven temperatures. From the information I learned, most coke ovens in China do not have them.

Fire fall management methods like those mentioned on the second floor have been used by Baosteel, and the effect is remarkable. The results show that: Baosteel's coke quality is among the best in the world. It shows that this technology is relatively successful.

The heating control system of our factory has not been established yet. It is said that the roof thermocouple is added to the fire management. I don’t know what the result is.

Fire fall management was introduced by Baosteel from Nippon Steel. I have only seen a brief introduction in some books. Currently, Baosteel should be the only one applying it in China. Editor-in-chief Yu Zhendong and Cai Chengyou, Liaoning Science and Technology Press ISBN: 9787538138658 is a relatively common book. Those who engage in coking should have this book in the factory. The introduction in it is relatively simple...

A brief discussion on the use of fire fall management in tamping coke ovens Miao Jun, Cui Jixing and Chen Weigang (Coal Coking Branch of Xinjiang Bayi Iron and Steel Company Ironmaking Branch of Baosteel Group) [Abstract] The core temperature of the coke cake is an important indicator for judging the maturity of coke. Due to the specific gravity of the coal pile in the tamped coke oven, it is difficult to measure the core temperature of the coke cake. How to judge the maturity of coke more concisely, and then judge whether the coke oven heating system is reasonable or not, has become an urgent problem that needs to be solved in our actual production. This article describes the significance of the application of the method of judging the maturity of coke cakes in tamping coke ovens in fire fall management and the installation and implementation of fire watching devices, hoping to bring some inspiration to everyone. [Keywords] Tamping coke oven coke cake center temperature fire drop 1. Introduction Heating system is an important part of coke oven thermal management. Each coke oven should prepare a heating system for different coking times based on the amount of coal loaded, the moisture content of the coal blend and the appropriate core temperature of the coke cake. The core temperature of the coke cake is an important indicator for judging whether the coke in the full carbonization chamber is mature. Usually, the coke cake reaching 950-1050℃ 30 minutes before coking is regarded as a sign of maturity. The core temperature of the coke cake is measured by inserting three thermocouples of different lengths vertically into the two coal loading ports (dust removal ports) on both sides of the coke in the carbonization chamber after the coal is loaded. According to the different heights of the top, middle and bottom. From the beginning of coal loading, the measurement is performed every hour until 30 minutes before coking. The average temperature of the last six temperatures measured at the upper, middle and lower points on both sides is used as the core temperature of the coke cake. 2. The significance of fire fall management in tamping coke ovens. Due to the process characteristics of tamping coke ovens, the pile specific gravity of coal entering the furnace is around 1.05. For such a specific gravity of the pile, it is conceivable that it is difficult to insert the temperature measuring iron pipe vertically. Due to the difficulty of the operation steps, we mostly use the furnace top space temperature value as a reference to judge the maturity of the coke cake. However, we all know that the temperature of the furnace top space is related to the coal loading height of the carbonization chamber and the flame burning length of the combustion chamber. It cannot truly reflect the maturity of the coke in the carbonization chamber, that is, it cannot accurately judge whether the standard temperature of the coke oven heating is reasonable or not. How to judge the maturity of coke more concisely, and then judge whether the coke oven heating system is reasonable or not, has become an urgent problem that needs to be solved in our actual production. “"Fire fall management" is actually the judgment of the ripeness of the coke cake. “The word "fire" comes from Japan. “"Fire falling" is an objective phenomenon that exists in the coking production process. It is a sign that the coke cake is basically mature. Japan adopts the "standard fire falling time" method for coke oven heating management. This method is different from the traditional method in my country. The traditional coke oven heating management method in my country is the "standard temperature" method. In my country, only Baosteel's coke oven adopts a heating management method based on "target fire time". Baosteel adopts the thermal management process of "fire fall management", which does not rely on "standard temperature". Its thermal management of coke oven heating is based on "target fire fall time". By utilizing certain inherent characteristics of the coal during the carbonization chamber carbonization process, the moment when the fire fall phenomenon occurs can be determined. This moment is called the "fire fall time", and the time elapsed from the time of coal loading to the fire fall time is called the "fire fall time". After the coking time of the coke oven is determined, the "target fire time" for coke oven heating must be determined, which is the basis of coke oven thermal management. The time elapsed from the time when the fire falls to the moment when the coke is pushed is called the "setting time". During the setting time period of the coke cake, the heating system of the coke oven remains unchanged, mainly to further uniformize the heating of each point of the coke cake, and to gradually increase the core temperature of the coke cake to the end temperature of coking. Obviously, the core content of Huoluo management is "accurate judgment of the maturity of coke cakes", which is exactly the judgment method we need. 3. Installation of the fire fall determination hole. The judgment of "fire fall" requires the naked eye to observe the color change of the raw gas exported from the carbonization chamber. This requires reserving a covered fire fall determination hole in a certain part of the export system (such as the riser standpipe). When making a fire determination, a small amount of raw gas escapes when the cover is opened, and the color change of the raw gas is observed with the naked eye under backlight. Usually when fire fall management is adopted, an observation hole for fire fall determination is installed at the riser during construction. There are two ways to install fire fall determination holes for retrofitting fire fall observation.: One way is to make a riser in advance, install a fire fall determination hole at the root, and build lining bricks to completely replace one of the risers in use. Then modify the replaced riser pipe again, and so on. ； Another way is to make the fire fall determination hole in advance, make a hole in the root of the riser pipe in the carbonization chamber at the end of coking and then directly weld the fire fall determination hole. ； Both methods have their own advantages and disadvantages: The fire fall determination holes replaced by the former are neat and standardized, but the construction is more difficult. Although the fire fall determination holes replaced by the latter are not neat, the operation is relatively simple (it is more time-consuming to open the holes). The replacement method we use is the latter: Use oxygen cutting to make a hole at the selected position of the riser pipe, then use a Ø8mm impact drill to drill holes in a radial pattern on the refractory bricks, and finally drill a hole larger than DN50 on the lining bricks, and then weld the fire drop determination hole connecting pipe. Attention should be paid to the installation of fire fall determination holes: ⑴ The opening should be at least 400mm from the root of the riser tube from the top of the furnace. ； ⑵ The diameter of the fire fall determination hole must be below DN80. ； ⑶ The hole cover and hole seat should have a certain joint surface and ensure good sealing. ； ⑷ The fire fall determination hole connecting pipe and the rising pipe are at an angle of 45°, and the length is selected to facilitate the operation of the observer. 4. The judgment of the maturity of coke cake is affected by the balance of heat supply and demand. The "fire falling moment" is a variable point in the retort process. When the heat supply is too large, the fire falling phenomenon will occur earlier; when the heat supply is too small, the fire falling phenomenon will occur later. “The key to the thermal management process of "fire fall management" is to control the moment when "fire fall" occurs during the coking process. Make the deviation between the actual "fire fall time" and the "target fire fall time" within the specified range, so that the coking effect reaches the point where the coke cake is fully mature and the heat consumed is the lowest. The original intention of using fire observation as a tamping coke oven is to judge the maturity of the coke cake. All you need to know is how to judge whether the coke cake is mature or not. 4.1. Characteristics of the fire falling phenomenon When coal is put into the furnace, in the later stages of carbonization, a phenomenon that we define as "fire falling" will occur. When the following characteristics appear, it can be determined that the coke cake in the carbonization chamber is "fired": ⑴ The temperature of each point of the coke cake is relatively consistent, reaching about 900~950℃. ； ⑵ The color of the waste gas changes from yellow to blue-white ； ⑶ The flame after burning of wild gas is transparent straw yellow ； ⑷ Among the components of raw gas, CH4 decreases sharply and H2 increases rapidly. ； ⑸ The calorific value of raw gas is significantly reduced ； ⑹ The temperature of wild gas increased significantly for a certain period of time before the fire fell and then dropped sharply. 4.2. Determination method of fire fall Any one of the six characteristics of the fire fall phenomenon mentioned above can be used to determine fire fall. The most convenient ones to apply are the 2nd, 3rd and 6th features. 4.2.1 Determine the fire fall based on the color of the raw gas. When judging the fire drop, remove the cover to release a small amount of raw gas, and observe the change in color of the raw gas with the naked eye under backlight. Before the fire fell, the color of the wild gas gradually turned from thick yellow to lighter. ； After a fire, the color of wild gas is blue-white. We designated the moment when the color of the wild gas changes from yellow to blue-white as the "fire fall moment." 4.2.2 Determine the fire fall based on the burning flame of the raw gas at night and when the color of the raw gas cannot be seen clearly, you can also ignite the raw gas in the riser and observe the color of the flame when the raw gas is burning through the fire detection hole. The moment when the flame turns to transparent straw yellow is the "fire falling moment". 4.2.3 Determine whether the fire has fallen into the carbonization chamber based on the temperature of the raw gas. Set a thermocouple in a certain part of the raw gas export equipment (such as the riser riser or the center of the bridge pipe) to measure the temperature of the raw gas. The temperature of raw coal gas will change regularly in each coking cycle. Using thermocouples, the moment when the temperature of raw coal gas reaches its highest point can be detected. The raw gas temperature mentioned here refers to the temperature after the raw gas leaves the carbonization chamber and before it is cooled by ammonia water. The phenomenon of a sharp drop in the temperature of wild gas before the fire is mainly due to the sharp decrease in the amount of wild gas, that is, the sharp decrease in the heat transfer medium. 5. Conclusion: Through practice, it is shown that the key content of using "fire fall" management: To determine the time when the fire falls, the "setting time" is guaranteed to be between 1-1.5 hours to determine the maturity status of the coke, so as to determine whether the setting of the coke oven heating standard temperature is reasonable or not. It is effective in tamping coke ovens. In addition, we determine the occurrence of fire fall time through the observation of fire fall judgment holes. We do not change the "standard temperature" method of thermal management to the "target fire fall control" method. Therefore, we only need to select 4-5 riser tubes in sections to install fire fall judgment holes to determine the maturity of the coke cake.

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Huoluo is to confirm whether the coke is mature some time before pushing the coke, and then simmer it for a while on the basis of maturity to ensure the quality of the coke.

This technology can ensure the quality of coke and at the same time reduce the heat consumption of coking.