JPS5950196B2 - How to determine whether a coke oven has caught fire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for determining with high accuracy the completion or omission of coal carbonization in a coke oven.

In the coal carbonization process in a coke oven, coal is normally charged sequentially into more than 100 kilns of the same shape and properties per furnace group, and after a certain period of standing time, the coal is removed from the kilns in the order of the charged kilns. Do the following.

Each kiln is equipped with more than 30 independent combustion furnaces (flues) on both sides, and is constantly heated with fuel supplied using blast furnace gas and coke oven gas while changing the gas flow path approximately every 30 minutes.

In this case, kilns are normally unloaded sequentially at fixed time intervals, so if a certain kiln is unloaded earlier than the scheduled time, the supplied fuel will be wasted, and if the unloaded kiln is unloaded later than the scheduled time, the loading time will be shortened. Too high a temperature leads to deterioration in coke quality.

For this reason, efforts have been made to maintain a constant fire-off time in the operation of coke ovens.

The most commonly used method for determining the fire path is to open the top cover 2 of the riser 1 shown in FIG. 1 and measure the color tone and amount of gas generated in the furnace.

In this case, a skilled person called Himi is required, and the work is difficult in a coke oven with more than 100 carbonization chambers, including opening at night or in the rain, and it is also difficult to open the riser pipe top cover. This has the disadvantage of causing air pollution.

In order to deal with this problem, some proposals have been made to determine whether the gas is missing from the temperature of the gas generated in the riser.

For example, as in Japanese Patent Publication No. 46-6497, when the flame passage temperature is Y, the maximum temperature of the generated gas is Yl, and the maximum temperature of the generated gas is A method has been proposed in which the missing temperature is calculated in advance when the maximum temperature is detected, and the temperature of the generated gas is successively measured thereafter, and the time when the temperature matches the pre-calculated missing temperature is used as a fire path.

However, when this method is applied, in reality, depending on the furnace conditions, the temperature of the generated gas may drop suddenly or gradually after the maximum temperature due to the temperature distribution in the coal, so it is not possible to judge whether the gas is missing or not. It is easy to cause errors.

Figure 2 shows the relationship between the maximum temperature of the generated gas and the missing temperature determined by experiment, and the regression equation for this figure is the above-mentioned equation
Corresponds to α1X1+β1.

Normally, the temperature of the generated gas during carbonization shows a pattern over time as shown in Figure 3, but when it drops from the maximum temperature A to the missing temperature B,
Considering the temperature gradient, which takes about 1 to 2 minutes for the temperature to drop by ℃,
The variation in the dropout temperature of ±20° C. in FIG. 2 corresponds to the variation in the fire-off time of ±20 to ±40 minutes, and the determination accuracy is not good.

Also, as in JP-A-49-103902, when the generated gas temperature is ¥2 and the elapsed time is X2, ¥2 - α2X2
+β2 (α2.β2 is a constant) is used to calculate the generated gas temperature at the target fire-down time, and the time when the difference between the calculated temperature and the actual generated gas temperature is less than the allowable value is determined to be a fire path. However, according to experiments conducted by the present inventors using this method, the correlation coefficient between the temperature of the generated gas at the time of failure and the fire-off time was as low as about 0.59, and the determination accuracy was insufficient.

Therefore, these known path determination methods have a limited accuracy.

Further, when controlling the fire fall time to a constant value using these path determination methods, the dead time of the path process is as long as 8 to 10 hours, making it difficult to perform effective control.

The present invention has been made to solve these problems, and is a method for predicting the fire path at an early stage without requiring fire sighting or opening the riser top cover, and further accurately determining the fire path at the end of carbonization. The purpose is to provide

The present invention will be explained in detail below based on the drawings.

FIG. 1 shows a schematic diagram of a coke oven. Reference numeral 1 denotes a riser pipe, which has a top cover 2 on top thereof, and guides gas generated in a carbonization chamber 3 to a collecting pipe 4.

5 is a thermometer for detecting the temperature of the generated gas rising inside the riser pipe 1.

When the temperature of the generated gas from the coal charging to the fire passage in a furnace is measured over time with a thermometer, a pattern as shown in Figure 3 is shown.

The present inventors have discovered that there is a relationship as shown in Figure 4 between the time from coal charging until the temperature of the generated gas reaches its maximum temperature and the fire-off time, and that the time when the temperature of the generated gas reaches its maximum point is We found that the fire path could be predicted with considerable accuracy.

That is, assuming that the elapsed time from coal charging until the temperature of the generated gas reaches its maximum point is xl, the fire path time can be predicted about 3 hours in advance by the relational expression of the predicted fire-fall time.

After the temperature of the generated gas reaches the maximum point in this manner, the temperature of the generated gas monotonically decreases as shown in FIG. 3 above.

This is due to the decrease in the amount of gas generated, which is a phenomenon at the end of carbonization.
This is because the amount of heat dissipated into the atmosphere through the furnace wall is greater than the amount of heat taken out of the furnace by the generated gas, and the temperature of the generated gas gradually decreases.

At this stage, if carbonization proceeds uniformly in all parts of the kiln, the rate of decrease in the amount of generated gas will be large, the gradient of decrease in the temperature of the generated gas will become large, and the end of carbonization (flame path) will occur at an early stage from the time when the maximum temperature is reached. appear.

On the other hand, if carbonization proceeds unevenly in various parts of the kiln, the rate of decrease in the amount of generated gas will be small, the gradient of decline in the temperature of the generated gas will be gradual, and the end of carbonization (flame path) will appear later after the maximum temperature is reached.

The temperature drop gradient after the maximum temperature is reached, and the difference between the actual fire-fall time Th and the predicted fire-fall time Th, that is, the prediction error Th-T
The inventors investigated the relationship between h based on actual data and found the relationship as shown in FIG.

As is clear from the relationship diagram in FIG. 5, when the temperature drop gradient is large, the actual course is faster than predicted, and when the temperature drop gradient is small, the actual course is slower than predicted.

Therefore, in order to increase the accuracy of estimating the fire fall time, the first step is to
It can be seen that the predicted firedown time can be modified by the falling temperature gradient.

If we pay attention to the relationship diagram in FIG. 5 again, even if the temperature drop gradient is the same, there are variations in the prediction errors.

When the present inventors analyzed actual data using various statistical methods including multiple regression analysis, it was found that the main causes of this variation were fluctuations in the amount of coal charged and fluctuations in the moisture content in the coal.

In other words, it was found that when the amount of coal charged and the moisture content in the coal were high, the fire path slowed down, and when it was low, the fire path became fast.

However, the degree of influence of moisture in the coal is smaller than the degree of influence of the amount of charged coal.

From these facts, it can be seen that in order to further improve the estimation accuracy of the burnout time, in addition to modifying the predicted burnout time based on the falling temperature gradient, it is necessary to make corrections based on the amount of coal charged and the moisture content in the coal. .

Based on the above, the present invention aims to improve the accuracy of estimating the fire-off time by comparing the elapsed time from the time of coal charging when the temperature of the generated gas reaches its maximum and the temperature gradient of the generated gas at the end of carbonization. By using a determination formula using the amount of coal input and the moisture content in the coal, the time of the course can be determined with high accuracy.

Specifically, for each coke oven, using a large amount of past performance data in advance, the final judgment fire-off time is set as ♀, and the elapsed time from the time of coal charging when the generated gas temperature reaches the highest. X
l, the falling temperature gradient of the generated gas is x2, the moisture content of the charged coal is x3
, the amount of charged coal is set as X4, and each constant a1. a2. a3. a4. Find b1.

Then, a formula for calculating the final judgment fire-off time using each of the determined constants is created for each coke oven, and in actual operation, the temperature of the generated gas during coal carbonization is successively measured and the point at which the maximum temperature is reached is determined. and at the time of detecting the maximum temperature, the above (1
), calculate the predicted flameout time, take necessary measures for reactor operation, continue to measure the generated gas temperature after that point, and when the temperature drop gradient becomes almost constant, change each variable of X1 to X4 as described above. By substituting and calculating the equation (2), it is possible to determine the fire fall time with high accuracy.

The maximum temperature of the generated gas usually appears about 3 hours before the failure, so according to the present invention, it is possible to predict this about 3 hours before the actual fire path, and it is possible to predict this temperature several tens of hours before the maximum temperature is reached.
Since the temperature drop gradient becomes almost constant within minutes, it is possible to estimate the time of the fire route with higher accuracy than about two hours before the actual time of the fire route.

The relationship between the estimated fire fall time according to the present invention and the actual fire fall time measured by the fire watch is shown in FIG. It can be seen that the error is reduced by half compared to the conventional method.

As a result, various effects can be brought about, such as shortening the placement time, saving fuel supply, and stabilizing the quality of coke.

As described above, the present invention predicts the fire path time based on the elapsed time when the maximum temperature of the gas generated during coal carbonization appears, and then predicts the fire drop based on the temperature drop gradient, the charged coal moisture content, and the charged coal amount. By correcting the time, the course time can be determined with high accuracy.

Therefore, there is no need for an experienced fire watcher and no need to open the top cover of the riser, so there is no air pollution.

Moreover, it is possible to judge the flame path time with higher accuracy than the conventional method, and it also enables effective fire-off time control by early control of fire-off time, improves productivity by shortening overall carbonization time, improves work efficiency, and improves coke quality. It brings about great effects such as stability.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a coke oven, Figure 2 is a diagram showing the relationship between the maximum temperature of generated gas and passage temperature, Figure 3 is a diagram showing the temporal pattern of generated gas temperature during coal carbonization, and Figure 4 Figure 5 is a diagram showing the relationship between the elapsed time to the maximum temperature of the generated gas and the measured fire-fall time, and Figure 5 is a diagram showing the relationship between the decreasing temperature gradient and prediction error.
FIG. 6 is a diagram showing the relationship between estimated fire fall time and measured fire fall time according to the present invention. In Figure 1, 1: riser pipe, 2: riser pipe top cover, 3: carbonization chamber, 4: collecting pipe, 5: thermometer, 6: combustion chamber,
7: heat storage chamber, 8: flue, 9: raw material charging port.

Claims (1)

[Claims] 1. Measure the temperature of the gas generated during carbonization in a coke oven, and use the relational expression (1) below to predict the passage time from the elapsed time from the time of coal charging when the temperature of the generated gas reaches its maximum. A method for determining a path in a coke oven, further comprising determining the path time using the following relational expression (2) based on the subsequent decreasing temperature gradient, the moisture content of the charged coal, and the amount of the charged coal.