What is the maximum coking time for a coke oven? ? Why can’t coke ovens be shut down or paused like blast furnaces? ?

Thread Content

The 25th National \"Safety Production Month\" in 2026: Everyone should talk about safety and know how to handle emergencies; identify and address potential risks and hazards. -------------------------------------------------- 1. Extended coking time: For a coke oven, the designed coking time for safe operation represents the actual coking time; any coking time that exceeds this value is considered an extended coking time. For example, if our design calls for achieving full production capacity within 24 hours of coking, then using 30 hours for coking would be considered an extension of the coking time. 2. There is no clear limit on how long the coking time can be extended; this time is determined primarily by calculating whether the gas produced is sufficient for its own heating needs. Of course, for coke ovens with external heating, it is difficult to determine this time period. However, if the time is too long, the graphite on the walls of the carbonization chamber will be burned away, resulting in an increased loss of gas. From a safety perspective, it is advisable that large coke ovens operate at no less than 15% of their designed production capacity, medium-sized coke ovens at no less than 20%, and small coke ovens at no less than 25%. In other words, the maximum coking time is approximately 100 hours for large coke ovens, 80 hours for medium-sized ones, and 50 hours for small ones. 3. As for how long the quality will remain good after that, it cannot be generalized; it depends greatly on the type of coal used, the bonding index Y value of the coal mixture, and the control of furnace temperature. It is necessary to conduct continuous tests based on the specific conditions of one’s own coke ovens. In our case, the ovens at Plant 1 are 5.5 meters in length, and 72 hours is currently the maximum duration for which the quality remains good ； Heat recovery in Plant 2 – it has also been used for over 200 hours. 4. After extending the coking time, the resistance to crushing and thermal strength increase, while wear resistance and reactivity decrease; however, after it is extended for a certain period, all these properties will deteriorate. 5. Regarding the impact on coke ovens, it mainly involves the damage to the entire masonry structure caused by cooling. Over time, the production of raw coal gas decreases; consequently, the pressure in the riser pipes cannot be maintained. This makes it easy for air to be drawn into the coke oven, which then burns away the graphite between the bricks. As a result, leaks occur in the coke oven, and the emission of smoke and flames becomes difficult to control. Second: Why can’t coke ovens be shut down or brought to a standstill like blast furnaces? Neither coke ovens nor blast furnaces can be shut down or taken out of operation at will; such actions are only resorted to as a last resort. Therefore, the question of why coke ovens can’t be shut down like blast furnaces is incorrect. However, if the furnace has to be idled or shut down, the damage caused to the coke oven may be greater than that to the blast furnace. Because: The carbonization chambers of coke ovens are constructed from silica bricks. When the ovens are left unheated, their temperature drops. Silica bricks have numerous phase transition points and ranges; improper temperature control can damage the brickwork, thereby affecting normal production in the future. A blast furnace has a shell on the outside with a refractory lining inside; even if damage occurs due to idling, replacing the lining is much easier than carrying out extensive repairs on a coke oven.