What does 46.6 seconds of commutation specifically mean?
Thread Content
The switching time for a coke oven is generally 46.6 seconds: gas supply is stopped for 15 seconds, followed by a pause of 0.8 seconds; then waste gas is switched over for 15 seconds with another 0.8-second pause; finally, gas supply is resumed for 15 seconds, for a total of 46.6 seconds. What do the 15 seconds for shutting off the gas, the 15 seconds for exchanging the waste material, and the waiting time refer to? Is turning off and turning on gas still a gradual process, or isn’t it stopped all at once? 、
It’s available in coking technology textbooks; take a good look at them.
No, it’s not there; it’s not even in the manual on modern coking production technology that I bought
The hydraulic cylinder pulls the pull rod, which in turn drives the lever. This process has a certain range of motion; it’s not like Sun Wukong, who can change shape instantly – it takes time. From the moment the lever starts moving until it reaches its intended position, it generally takes 15 seconds, with a pause of 0.8 seconds. Of course, these times can be adjusted appropriately in the program according to actual conditions; they’re not fixed
A hydraulic cylinder is used to drive the gas valve in order to turn the gas on and off; there is a time requirement for the actions of the valve and the hydraulic cylinder, usually 15 seconds. The first pause is for drawing in air to burn off the gas remaining in the gas branch pipes and lower nozzles ； The second pause is for the coke oven to draw in air, filling the vertical flue; once the gas enters, it can burn immediately.
Thank you! There are two more questions: 1. Since there is no gas combustion during the exchange process, will the temperature of the combustion chamber decrease? 2. At the end of the exchange process, once the gas enters, it burns immediately; as a result, the amount of SO2 produced is much higher than normal. Why is this?
OP, have you never seen an actual coke oven in operation? The combustion chamber has ascending and descending air flows. The process of exchange involves a pair of combustion chambers, that is, vertical flues; one has an upward airflow while the other necessarily has a downward airflow. The temperature will definitely change, but due to heat transfer and thermal radiation, the temperature throughout the combustion system remains balanced. Besides, the entire switching process takes just a few dozen seconds, so any drop in temperature is negligible. The exchange is complete. How is it detected that the S02 produced by gas combustion is above the normal level?
Please refer to the attachment; one shows the SO2 concentration in the exhaust gases, and the other shows the NOX concentration in the exhaust gases. It is clear that during the exchange process, SO2 levels decrease immediately, then rise sharply, before returning to normal levels. Meanwhile, NOX decreases immediately and then gradually returns to normal levels. I think the reason why NOX does not rise sharply is due to the decrease in combustion chamber temperature during the exchange process. Otherwise, how can you explain these phenomena?
Sorry, I forgot to attach it earlier; here’s the link for you~~http://bbs.hcbbs.com/thread-1595683-1-1.html
In our online flue gas monitoring system, there has never been a situation where SO2 levels suddenly increased during exchanges; on the contrary, when air is introduced in large quantities as a result of such exchanges, the oxygen content rises while SO2 levels drop.