JPH04272992A - Method for predicting expansion pressure in process of coke production - Google Patents

Abstract

PURPOSE:To predict an expansion pressure in a process of carbonization of coal with a very simple means. CONSTITUTION:A peak of gas pressure in a coal layer which is in a softened and molten state is detected by carbonizing a sample of coal in a small test furnace, providing a probe for measuring the gas pressure which is made of a stainless tube and has a inner diameter of 1mm and an outer diameter of 2mm in a given position (which is centered in the longitudinal direction and the widthwise direction and spaced 125mm from the bottom of the furnace) accompanied with a detection terminal of a temperature-measuring means and confirming by temperature that the coal positioned at a probe is in a softened and molten state. An expansion pressure of coal in a process of coke production can be predicted from the relationship between the peak value and the expansion pressure measured in a test furnace with a movable wall.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for predicting expansion pressure during the carbonization process of coal.

0002

2. Description of the Related Art During the process of producing coke from coal in the carbonization chamber of a coke oven, the coal expands and exerts pressure (expansion pressure) on the walls of the coke oven. This high expansion pressure can damage the walls of coke ovens (for example, in the U.S.
Steel Fairfield Steel Works No. 2 coke oven (J.F. McDermott et al.
, Iron & Steel Maker, 13
(1986), 51)) Management of expansion pressure is an important issue in furnace management.

[0003] In recent years, no attention has been paid to inflation pressure in Japan. However, in the future, the proportion of coal with a high degree of coalification (low volatile content), which is said to have a high expansion pressure, will tend to increase, and the expansion pressure will need to be controlled below the limit value based on the strength of the coke oven body. There is a need.

When coal is carbonized in a carbonization chamber, as the carbonization progresses and the coal turns into coke, the softened and molten coal layer moves from both the left and right furnace walls to the center of the carbonization chamber, but normally the expansion pressure is known to exhibit the maximum value, that is, the maximum expansion pressure, when the softened and molten coal seams meet in the center of the coking chamber. In actual operation, this maximum expansion pressure poses a problem in terms of damage to the furnace body, so it is necessary to manage the maximum expansion pressure to a limit value.

Since the expansion pressure cannot be measured in an actual coke oven, it is usually determined by Koppers and Jenkner (H. Kopp).
ers and A. Jenkner,Fuel,
10 (1931), 232, H. Koppers a
ndA. Jenkner, Fuel, 10 (193
1), 273) was developed using a movable wall furnace (a special test carbonization furnace with a movable wall on one side), and the maximum expansion pressure measured in the movable wall furnace was 10 to 15 kPa, which was the temperature of the coke oven furnace body. This is considered to be the permissible limit value based on strength.

[0006] However, this test furnace is very expensive;
Moreover, the amount of coal sample is large (approximately 400 kg), and it is not a simple measuring method. Furthermore, the reproducibility of measurement results is poor;
The problem is that it is not possible to respond quickly when changing the blend of coking coal or the operating conditions of the coke oven.

[0007] It is also known that the cause of expansion pressure is the gas pressure within the coal seam, which is in a softened and molten state.
ppers and Jenkner found that in a movable wall furnace, there is a correlation between the maximum expansion pressure when softened and molten coal seams meet in the center of the coking chamber and the peak gas pressure in the coal seams that are in the softened and molten state at the same time. It is shown that. However, as far as measuring the gas pressure peak value in a coal seam in a softened and molten state using a movable wall furnace, there are many problems similar to when measuring expansion pressure using a movable wall furnace.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of predicting the expansion pressure during the carbonization process of coal using extremely simple means.

[0009]

[Means for Solving the Problems] The present invention is characterized in that a coal sample is carbonized in a small test furnace, and a probe with a tube diameter small enough to ignore the influence of heat conduction is used as a side heating means. With the detection end attached, place the probe terminal so that it faces the center of the furnace length and furnace width direction and near the bottom of the furnace, and confirm that the coal sample in the area where the probe terminal is located is in a softened and molten state due to the side temperature. , the expansion pressure of coal was predicted by detecting the gas pressure peak in a coal sample layer in a softened and molten state, and from the correlation between this peak value and the expansion pressure measured in a wall-type test furnace. It is characterized by a method for predicting coal expansion pressure during the coke manufacturing process.

The present invention will be explained in detail below. The cause of expansion pressure is the gas pressure in the coal seam that is in a softened and molten state, and the maximum expansion pressure when the softened and molten coal seams meet in the center of the coking chamber is the same as the coal that is in a softened and molten state at the same time. It is known that there is a correlation between the gas pressure peak values within the layer. Therefore, the inventors focused on the gas pressure peak when the softened and molten coal seams meet in the center of the carbonization chamber, and as a result of repeated research on a means to easily predict the expansion pressure during the carbonization process of coal, we found that By clarifying the process of carbonization in the test furnace, we discovered that it is possible to detect gas pressure peaks in a coal seam in a softened and molten state using a small carbonization test furnace. We also found that there is a good correlation between the gas pressure peak of the coal in the softened and molten state measured in this small carbonization test furnace and the maximum expansion pressure measured in the movable wall furnace. The present invention was completed based on this knowledge.

[0011] A small carbonization test furnace (for example, as shown in Example 1, the furnace length is 669 mm, the furnace height is 410 mm, and the furnace width is 425 mm).
When coal is carbonized at 1 mm), the influence of heat transfer from the top and bottom of the furnace cannot be ignored. Therefore, coking progresses considerably not only from the direction of the furnace wall, but also from the direction of the furnace top and bottom, and from the direction of the furnace lid. The inventors discovered that in this small carbonization test furnace, a bag-shaped softened molten layer is formed during the coking process, and the gas pressure inside the uncarbonized coal seam inside the softened molten layer increases. Therefore, in order to detect a gas pressure peak in a coal seam that is in a softened and molten state, it is necessary to confirm by temperature that the coal at the probe position is in a softened and molten state. Furthermore, when the coke sample was dismantled after carbonization, it was found that the area where the softened and molten coal seams met in the center of the coking chamber was small, and the location of the coalescence was quite close to the bottom of the furnace. Therefore, care must be taken in choosing the location of the probe. In addition, we found that the large diameter probes conventionally used to measure gas pressure in movable-wall furnaces have a non-negligible effect on heat conduction in small carbonization test furnaces, and have an impact on the carbonization process. Therefore, it is necessary to use a probe that is sufficiently thin so that the influence of thermal conduction can be ignored. Furthermore, the gas pressure peak in the coal seam in the softened and molten state measured in this small carbonization test furnace and the movable wall furnace (for example, as shown in Example 2, the furnace length is 600 mm and the furnace height is 600 mm)
It was found that there is a good correlation between the maximum expansion pressure measured at a furnace width of 400 mm).

Based on this knowledge, the inventors invented the following specific means. In the present invention, a small carbonization test furnace (furnace length 669 mm, furnace height 410 mm, furnace width 425
A small amount of coal sample (approximately 100 kg) is carbonized using a coal seam (mm), and the gas pressure within the coal seam in a softened and molten state is measured. The gas pressure measurement probe uses a stainless steel tube with an inner diameter of 1 mm and an outer diameter of 2 mm, and a thermocouple (K-type sheath thermocouple; diameter of 1 m).
m; sheath material SUS304; non-grounding type) is tied. This probe is installed at a predetermined position (center in the furnace length/furnace width direction, 125 mm from the furnace bottom) when charging coal. In order to prevent the probe from shifting, it is fixed with cardboard, a hole is made in the surface of the charging can that corresponds to the furnace lid, and the probe is led out of the furnace through the hole and connected to a gas pressure measuring device. In this way, changes in gas pressure and temperature over time are measured.

[0013]Even if the specifications of the furnace and the heating conditions are different, the specifications of the thermocouple-associated probe may be the same. However, regarding the location of the probe, it is necessary to disassemble the coke sample after carbonization and find the location where the softened and melted coal seams meet in the center of the coking chamber, and then install the probe at that location.

The gas pressure increases before the temperature of the coal at the probe position reaches the softening and melting temperature, and this is the gas pressure within the uncarbonized coal seam surrounded by the softening and melting coal seam. Therefore, in order to determine the gas pressure peak when the softened and molten coal seams meet in the center of the coking chamber, it is necessary to read the peak immediately before the gas pressure returns to zero. When the gas pressure returns to 0, it means that the coal at the probe position has gone through a softened and molten state and then solidified again. Furthermore, at this point, it is necessary to confirm by temperature that the coal at the probe position is in a softened and molten state. In this way, the gas pressure peak value within the coal seam in a softened and molten state is measured.

In addition, for several types of coal, we measured the gas pressure peak in the coal seam in a softened and molten state in a small carbonization test furnace, and also measured the same carbonization conditions (pulverized particle size, charging density, moisture, etc.) using a movable wall furnace. The expansion pressure is measured at the furnace temperature) and the correlation between the gas pressure peak value and the expansion pressure is clarified in the form of a diagram, table, or correlation equation.

By using this correlation (diagram, table or correlation formula), the gas pressure peak value in a coal seam in a softened and molten state measured in a small carbonization test furnace can be calculated without measuring the expansion pressure in a movable wall furnace. From this, the expansion pressure of coal can be predicted.

However, it is known that the pulverized particle size and charging density of coal have a great influence on the expansion pressure, and the higher the charging density and the larger the pulverized particle size, the higher the expansion pressure. It is also known that the expansion pressure varies depending on the furnace temperature. Therefore, if the pulverized grain size, charging density, and furnace temperature of coal are different, the influence of these on the expansion pressure should be investigated and the expansion pressure should be corrected, or the coal should be brought to a softened and molten state in a small carbonization test furnace under each condition. What is necessary is to measure the gas pressure peak in a certain coal seam and also measure the expansion pressure in a movable wall furnace to clarify the correlation between the gas pressure peak value and the expansion pressure.

[0018]

[Example] Example 1 Here, we will introduce a small carbonization test furnace (inner dimensions of charging can: furnace length: 669 mm, furnace height: 410 mm) owned by each Heisha steelworks.
A carbonization test was conducted using a furnace with a width of 425 mm. Normally, this test furnace is used to carbonize incoming coal and examine the coke properties.

The gas pressure of coal shown in Table 1 was measured using the method of the present invention (described in the section on means for solving the problems). The pulverized particle size of the coal at this time is 85% of 3 mm or less, the charging density is 0.86 t/m3 on a dry coal basis, and the moisture content is 3%.

FIG. 1 shows the changes in gas pressure and temperature of coal A (second time) over time. According to this figure, it can be seen that the gas pressure increases before the temperature of the coal at the probe position reaches the softening and melting temperature, and when the temperature of the coal at the probe position exceeds the softening and melting temperature, the gas pressure becomes zero. From this figure, the peak value just before the gas pressure returns to 0 is 106 kPa, and the temperature of the coal at the probe position is 435°C at this point, so the gas pressure peak value in the coal seam, which is in a softened and molten state, is 106 kPa.
It can be seen that it is.

Table 2 shows the results of measuring the gas pressure within the coal seam in a softened and molten state for each coal. From this table, it can be seen that the gas pressure can be measured with good reproducibility.

[0022]

[Table 1]

[0023]

[Table 2]

Example 2 Small carbonization test furnace (inner dimensions of charging can: furnace length 669 mm furnace height 4
10mm furnace width 425mm) and movable wall furnace (furnace length 600mm)
Using a furnace height of 600 mm and furnace width of 400 mm, the gas pressure peak and expansion pressure in the coal seam in a softened and molten state were measured by the method of the present invention (described in the section of means for solving the problems). The pulverized particle size of the coal at this time is 3 mm or less, 85%,
Charging density is 0.86t/m3 based on dry coal, moisture content is 3%
It is.

FIG. 2 shows the relationship between gas pressure peak and expansion pressure in a coal seam in a softened and molten state. This figure shows that there is a good correlation between the two. From this figure,
The expansion pressure of coal can be predicted from the peak gas pressure in the softened and molten coal seam measured in a small carbonization test furnace.

[0026]

[Effects of the Invention] According to the present invention, gas pressure can be easily and reproducibly measured using a small amount of coal sample, and expansion pressure can be predicted.

[0027] This makes it possible to predict the expansion pressure of the coal blend when changing the blend of raw material coal or the operating conditions of the coke oven, preventing damage to the oven wall due to the expansion pressure, and ultimately reducing the lifespan of the coke oven. It also leads to extension, and the economic effect is large.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing changes over time in gas pressure (second time) and temperature when A coal was carbonized in a small carbonization test furnace.

FIG. 2 is a diagram showing the relationship between the gas pressure peak value in a coal seam in a softened and molten state measured in a small carbonization test furnace and the expansion pressure measured in a movable wall furnace.

Claims (1)

[Claims] Claim 1: A coal sample is carbonized in a small test furnace, and a probe with a tube diameter small enough to ignore the effect of heat conduction is attached to the detection end of the side heating means and placed at the center of the furnace length and furnace width direction. Confirm that the coal sample at the part where the probe terminal is located is in a softened and molten state due to the side temperature, and the gas pressure in the coal sample layer that is in a softened and molten state is Prediction of coal expansion pressure in a coke manufacturing process, characterized by detecting a peak and predicting the expansion pressure of coal from the correlation between this peak value and the expansion pressure measured in a movable wall test furnace. Method.