JPS59221583A - Method of monitoring internal state of vertical type furnace - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for determining the internal state of a vertical furnace near the surface of the inner wall of the furnace by using a differential method to determine the temperature change that appears near the surface of the inner wall of the furnace.

A blast furnace for iron making is a type of vertical furnace, and the raw materials (iron ore, coke, etc.) charged from the top of the blast furnace descend while encountering reducing high temperature gas rising inside the furnace. During this process, the reduction reaction of iron ore progresses in stages. The reduction reaction of iron ore in a blast furnace is influenced synergistically by various factors, and when managing operations, it is necessary to make comprehensive judgments using a large amount of data. However, it is extremely effective to classify and understand the descending status of charged raw materials or the rising status of reducing gas, etc. into several nodes, especially if these conditions are within the proper operating range. For determining whether or not the above range is exceeded, or whether or not the range is frequently exceeded, understanding using the above pattern classification is an extremely important management item to ensure the safe operation of blast furnaces. obtain.

The present invention has been made with attention to such a situation, and it is an object of the present invention to provide a method that can easily monitor physical phenomena inside a vertical furnace, especially near the inner wall surface of the furnace. .

The monitoring method of the present invention that has succeeded in achieving the above object is to measure the temperature near the inner wall surface of a vertical furnace, express the temperature change over time by the difference method, and express the temperature change by the difference method. The gist of this is that the situation inside the furnace is determined based on temperature change information.

A further overview of the operational status of the blast furnace shows that iron ore and coke are charged alternately at regular intervals, and the iron ore is gradually lowered at a rate depending on the operating conditions of the blast furnace. reduction is progressing. In other words, the iron ore layer and the coke layer descend while maintaining a state of alternating layers in the direction of the furnace height, but the reduction reaction that progresses during this period is uneven in the radial direction, and generally On the core side, softening and melting of the iron ore layer progresses at the furnace foot stage, but on the furnace wall side, reduction progresses slowly and the alternating arrangement of iron ore and coke layers occurs almost directly above the raceway in the morning glory section. It is said that it will be maintained until Therefore, on the furnace wall side, the iron ore layer and the coke layer descend in an almost uniform manner from the furnace chamber to the morning glory, and on the other hand, the reducing gas generated in the raceway fuses between the coke particles and the iron ore layer. The gas rises through ventilation and low resistance areas such as between the belt and the cohesive zone, but this rising state of reducing gas or falling state of the charge is stable during blast furnace operation. It's not that I'm doing it.

In other words, if a stagnant layer or deposits are formed inside the furnace wall, if refractory material falls off from the inner surface of the furnace wall, or if the shape of the raceway changes or the core coke fluctuates, ,
This may lead to stagnation of the charge or, conversely, rapid unloading, or abnormalities in the flow of rising gas (a blowout phenomenon) may occur due to changes in the shape of the cohesive zone in the furnace. It may occur. Of course, such abnormalities occur throughout the furnace, but abnormalities on the furnace core side are so to speak a black box and are difficult to discover. However, consideration has been given to embedding various types of sensors to obtain various information on the furnace wall side, and the present inventors have developed a method to obtain various information on the inside of the furnace wall by skillfully utilizing the temperature information inside the furnace wall. The above configuration was arrived at with the intention of determining the situation inside the furnace near the surface area.

The meaning of measuring the temperature near the inner surface of the furnace wall should be interpreted in a broad sense), when measuring the temperature of the wall itself on the inner wall surface and when measuring the temperature inside the furnace adjacent to the wall surface. Of course, these areas also include the case where the temperature inside the wall or inside the furnace is measured.

The temperature measurement means or temperature measuring device may be freely selected by the person implementing the present invention, but the temperature distribution detection sensor invented by the present applicant (Utility Model Application No. 55-1.05140)
, No. 57-81531, Japanese Patent Application No. 56-197559) is recommended. - Fig. 1 is a partial cross-sectional diagram showing an example of a sensor recommended as a temperature sensor used in the present invention, and Fig. 2 shows the main part of the cross section taken along the IT-N line in Fig. 1. Reference numeral 2 in the figure indicates a temperature distribution detection sensor (hereinafter referred to as "temperature sensing mechanism member").

Temperature sensing part 3a+3 configured in this temperature sensing mechanism member 2
Disc-shaped fin 4 corresponding to the position of b+...
a, 4b... have been provided for the first time in a long time to be circumscribed orthogonal to the temperature sensing mechanism member 2, and these disc-shaped fins 4
a r 4 b... is the positioning means 6a+
, 6a216a3+6a4 j6b, +, 6b2r
It is fixed to the protective outer tube 5 via """. Therefore, the temperature measurement response sensitivity is significantly improved by the disc-shaped fins 4a+4b.

Furthermore, the temperature sensing mechanism member 22 disc-shaped fin 4at4b...
...and the respective spaces separated by the protective outer tube 5 are filled with an insulating material 7, which ensures the durability of the temperature sensing mechanism member 2, blocks heat dispersion in the length direction, and improves temperature measurement accuracy. can be increased. These sensors have multiple temperature-sensing parts set in the length direction.For example, if they are buried in the wall thickness direction, the temperature distribution in the thickness direction can be measured, so the inner wall surface is always measured. This sensor has the advantage of being able to obtain temperature information from the vicinity of the furnace (or inside the furnace), making it an ideal sensor for implementing the present invention.

FIG. 3 is a conceptual explanatory diagram showing a state in which the above-mentioned sensor is embedded in the blast furnace wall, and the blast furnace wall 4 is connected to the iron shell 1. It is composed of a stamp 2 and a fireproof wall 3, and a temperature sensor 5 is embedded in the wall thickness direction of the blast furnace wall 4. Reference numeral 6 indicates a temperature-sensitive point on the surface of the inner wall, and in the illustrated example, a type of sensor 5 that protrudes into the charge (iron ore layer 7 and coke layer 8) is used, but the temperature-sensitive point 6 is located on the refractory wall. There is no problem even if it stays within 3. Iron ore layers 7 and coke layers 8 are formed alternately and fall at a rate depending on the operating rate of the blast furnace, while reducing gas is rising, so the temperature sensitive point 6 is affected by the cooling effect of cold solids coming down from above. It is affected by thermal reduction reactions caused by hot gas rising from below, and the temperature can be detected according to the degree of these influences. When we closely observed the changes in the detected temperature over time, we found that, although they appear to be very different, if we sort out these phenomena, we can classify them into the following four cases.

(1) Little temperature change.

(2) The pitch of temperature change approximately corresponds to the charging pitch of iron ore and coke at the top of the furnace.

(3) The temperature is 8. rise sharply.

(4) The temperature drops rapidly.

On the other hand, when we compare the inferred results of the situation inside the reactor with the observation results of (1) to (4) above, we find that (5) whether the descent of the charge has stopped or whether there is a stagnation layer or a layer around the temperature sensing point 6; Temperature changes are not detected when deposits are formed. - (11 (B>) When the charge is descending at a steady speed, the charge from the top of the furnace reaches temperature sensing point 6 almost exactly after a certain period of time, resulting in a temperature corresponding to the charging pitch. A change is detected.-(2) (C) Increase in gas flow along the refractory wall (formation of so-called peripheral flow) occurs, and the temperature rises rapidly due to the heat of the gas.-(3) (To) When the unloading speed of the charge increases, the temperature drops rapidly due to the cooling effect. -(4) As mentioned above, the detection results of (1) to (4) are almost (5)
It turns out that it corresponds to the phenomenon of ~(D),
When we applied this method to an actual operating furnace and performed long-term measurements, we found that the above-mentioned correlation always holds true qualitatively. However, it has been difficult to quantitatively understand these relationships and provide feedback to blast furnace operations. Therefore, we explored other ways to use this temperature information.

As a result, while inputting the above-mentioned temperature information moment by moment, we investigated how it changes in each short period, and thought of grasping it as a temperature difference value. That is, for example, about 30 seconds (preferably, it is an analog quantity, but in the case of large thermal equipment such as a blast furnace, about 30 seconds is sufficient. However, it should not be limited to 30 seconds). Input temperature measurement results every short cycle. On the other hand, the temperature detected by the temperature sensor ~5 changes moment by moment as the charge falls and furthermore due to the high temperature gas rising in the furnace, and is given as a function of time 'I'-f(t). In the function T=f(t), as the value of time t, from to to h, 2h
, 3h , . . . The values of temperature T when given equal intervals of increase are To, T, , T, respectively.
2. It is represented by... And each difference value T,
~TO- (To 7Δt).

T2-T, -Δ, (HiT, /Δt) + T3 T
Find 2 cranes (yo 2 ha 1) +... The present invention was completed by focusing on the use of this difference value as temperature change information. By the way, Figure 4 0), (b), (
Figure 5 (a), (b), (c), and (c) are graphs in which the raw temperature information obtained every 30 seconds by the temperature sensor is expressed directly on the vertical axis. Difference values are obtained by organizing the above-mentioned raw data using the difference method, and the graphs express these difference values on the vertical axis, with the horizontal axis showing the passage of time in both cases. In addition, Figure 4 (a) ~)
The temperature observation results described with the symbols (1) to (4) above correspond to the temperature change states of each category shown in (1) to (4) above. Figure B) to)
Among the phenomena shown in , "gas blowout" refers to a phenomenon in which a large amount of gas in the furnace suddenly passes along the inner peripheral surface of the refractory wall 3.
"Slip" refers to a phenomenon in which a charge such as iron ore is suddenly unloaded along the inner peripheral surface of the fireproof wall 3. "Drop in rO/C" expresses the normal state in which the charges are unloaded at approximately the same frequency as the charging pitch at the top of the furnace. Furthermore, “
"Stagnation layer" refers to any immobile layer including a deposit layer. If you look at Figure 4 (a) to 4), the temperature change curve is generally gentle, so it is possible that the presence or absence of change or the degree of change may be inaccurate; )
), the vertical axis is the difference value, so it is possible to accurately determine whether or not there is a change, or the extent of the change. In addition, FIG. 5(a) to 5) show the difference values displayed on a CRT screen, and by sequentially monitoring the situation inside the furnace, it is possible to immediately feed back to adjustments etc. outside the operating prefecture.

In addition, for the difference values expressed in Figure 5 G) to), the upper and lower limits that are permissible in terms of blast furnace operation are set, and the degree and frequency (number of times per unit time) of exceeding these upper and lower limits are determined.・By checking the total number of times, slowness of recovery, etc.), or by setting upper and lower limits that are not allowed to be exceeded and performing similar checks ( It is also possible to set a limit value for each check item and manage it by comparing it with the limit value), and by issuing a notification according to each content, the operator can immediately understand the existence and extent of abnormalities. As a result, it is possible to quickly take measures such as wind reduction, humidity adjustment, and air temperature adjustment. Figure 6 shows an example of applying this method to blast furnace operation.

Since the present invention is configured as described above, it is possible to quickly and accurately grasp the situation near the inner wall surface of a vertical furnace from the difference value of temperature change information, and to take prompt action in response. became.

In particular, in blast furnaces, it is possible to detect abnormalities related to the unloading of the charge and the rise of gas, which is extremely useful for adjustments outside the prefecture where the furnace is operated.

Figure 1 is a partial cross-sectional diagram of the temperature sensor, Figure 2 is the
The main part of the cross-sectional diagram along the ■-■ line in the figure, Figure 3 is a cross-sectional view of the blast furnace chest, Figure 4 (() to 2) is a graph with raw temperature information on the vertical axis, Figure 5 (A) (-) is a graph in which the vertical axis is the temperature difference value, and FIG. 6 is a flow diagram in which the furnace condition monitoring method using the difference value is applied to blast furnace operation.

4...Blast furnace wall 5...Temperature sensor 6...
・Temperature sensitive point 7...Iron ore layer 8...Coke layer Applicant Kobe Steel, Ltd. Time (hr) Time [hr) 433 1 hour CI+r) Time (br) Time (hr) Time (11r) Time (hr)

Claims (1)

[Claims] A vertical type furnace characterized by measuring the temperature near the inner wall surface of the vertical type furnace, expressing the temperature change over time by a difference method, and determining the situation inside the furnace based on the temperature change information expressed by the difference method. Method for monitoring the condition inside the furnace.