What is the drop in direct temperature of a coke oven? How is it utilized?

It refers to the temperature from the moment of direction change until temperature measurement; generally, the temperature measured plus the decrease in temperature gives the actual temperature of this viewing port

In fact, it is the cooling temperature; this decrease value must be added after each measurement of the straight-line temperature.

How do I measure the temperature drop?:

Measurement of cooling temperature (decrease value) 1. The cooling temperature must be measured under conditions of normal operation of the coke oven and a stable heating regime. 2. Select 9 connected combustion chambers with normal heating, and conduct measurements in the temperature-measuring flues on the machine-side and fuel-side respectively. 3. Measurements are taken at the branch unit and on the focal side; they begin 20 seconds after the direction change, and then once per minute until the next direction change (or 2–3 minutes before it). 4. Divide the measurement results into the machine side and the focal side. Using the average temperature value at the same measurement time, the difference between the average temperature per minute after the direction change and the average temperature 20 seconds after the change represents the temperature drop for that minute. Using the direction-change time and the temperature drop as coordinates, smooth curves for the machine side and the focal side are plotted, which constitute the cooling curves. 5. Divide the entire furnace into several sections according to the measurement sequence and speed of the straight-line temperature. Then, the cooling correction value is determined from the cooling curve based on the measurement time in each region. 6. The fire hole cover should only be opened during measurements, and it must be closed immediately after the measurements are completed.

The purpose of adding a decrease value after standard flue measurement is to convert the measured temperature into the temperature at 20 seconds after the conversion

The exact term is cooling temperature. If a 5-2 sequence is used, measure the standard flue of the 6 connected combustion chambers under normal heating conditions. Measurement begins when the direction changes from upward to downward (especially when burning blast furnace gas, it is not easy to observe the direction change), and the data at this point is considered the first set of data. Then measure every 1 minute. (For easier measurement, the flue cover can be placed in reverse; it can be opened and closed by kicking it during measurement, without the furnace temperature being affected by leaving it open for long periods of time.) ； If the temperature of the subsequent measurement is higher than that of the previous one, the latter’s temperature is used as the reference. Then, with time as the horizontal axis and the difference as the vertical axis, a curve is drawn; this curve is compared with the previous one, and the decrease value in the temperature measurement system is adjusted accordingly. The above are my personal opinions. This post was last edited by Jin Yusi on 2009-3-6 12:49.]

Thank you to the two friends above! I’ve learned something from it

In order to convert the measured temperature of a specific heating channel into the highest temperature 20 seconds after the direction change, so as to compare the uniformity of the temperature throughout the furnace and prevent any heating channel temperature from exceeding the limit value, it is necessary to measure the decrease in temperature of that heating channel during the period of direction change, that is, the cooling temperature. When the 9-2, 2-1 sequence is used for coke extraction from the coke oven, 8 to 10 combustion chambers that are operating properly and continuously should be selected; when the 5-2 sequence is used, temperature measurement channels in 6 consecutive combustion chambers should be used to measure the cooling temperature. This is because the carbonization chambers adjacent to these combustion chambers have different coking times, and the average value obtained is representative. Measurements are taken on the branch unit side and the focal side. The measurement method involves taking readings at a rate of once per minute starting from the moment the flame in the post-switch combustion chamber disappears, which is equivalent to 20 seconds after the switch, and continuing until the next switch occurs or 2–3 minutes before the switch. After measurement, the sight glass cover should be closed to avoid affecting the accuracy of the measured temperature. The measurement results are used to calculate an average temperature for each heating channel at the same temperature measurement time on the machine side (or furnace side). The difference between this calculated average temperature per minute and the average temperature 20 seconds after the switch-over represents the amount of cooling temperature drop at that respective time. With the temperature drop and commutation time as the vertical and horizontal axes respectively, curves are plotted for the subunit and the focal side; this curve is known as the cooling curve. From the curve, it is possible to determine the amount of cooling temperature drop required at various times after the straight-line temperature measurement and after the exchange. The cooling temperature must be measured under conditions of normal coke oven operation and a stable heating regime; during measurement, the gas flow rate, flue draft, inlet opening degree, and the timing of coke pushing should not be altered. 　 The cooling temperature is related to factors such as the composition of the gas, the commutation cycle, the temperature in the furnace, the coking time, and the air excess factor. In production, when there are significant changes in the coking time or the heating regime, the cooling temperature should be measured again ； When the coking time is stable, the cooling temperature should be measured again at least once a year.