JPH0227625B2 - TATEGATARONIOKERUROHEKIHYOMENGASURYUNOTSUYOSASUITEIHOHO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for estimating gas flow distribution in a furnace during the operation of a vertical furnace, such as a blast furnace, and more specifically, the present invention relates to a method for estimating gas flow distribution on the furnace wall surface from the upper part of the tuyere to the upper part of the furnace chest of the blast furnace. The present invention relates to a method for stably estimating the long-term stability.

The ultimate purpose of a blast furnace is to produce large quantities of high-quality pig iron stably, efficiently, and at low cost. In line with this purpose, under the given raw material/fuel conditions and equipment conditions, various operations such as raw material/fuel charging, melt extraction, air blowing, and top gas control are performed to control the reaction in the reactor. are doing. Although accurately understanding the situation inside the furnace is a major premise for performing these controls, the inside of the blast furnace is a kind of black box, and it is difficult to dynamically understand the situation inside the furnace. It was considered difficult. The present invention relates to a method for estimating and grasping the actual state of gas rising in a furnace, particularly the strength of gas flow on the surface of the furnace wall, with high accuracy, and thereby aims to strengthen raw material/fuel charging and air blow control. It is something.

The hot air blown in from the blast furnace tuyere burns fuel in the raceway, becomes reducing gas, and progresses through the reduction of the iron ore as it travels from the morning glory section through the furnace chest to the furnace mouth, while also undergoing certain changes. Finally, it is discharged from the top of the furnace. In other words, O ₂ in hot air and
The H ₂ O component reacts with coke, heavy oil, etc. to produce CO and H ₂
While passing from the morning glory section to the furnace chest, it changes into CO ₂ and H ₂ O, forming various gas flow distributions in the furnace. This in-furnace gas flow can be roughly divided into the so-called core gas flow, which flows near the center of the blast furnace, and the furnace wall surface gas flow, which flows along the blast furnace inner wall surface (including the vicinity of the surface) (hereinafter referred to as peripheral gas flow). Can be done. Generally, when the central gas flow becomes excessive, there is a margin in terms of ventilation and the heat load on the furnace wall can be reduced, but the gas utilization rate deteriorates and the fuel ratio tends to increase. On the other hand, when the surrounding gas flow becomes excessive, the gas utilization rate increases, but there is a tendency for the ventilation to deteriorate and the heat load on the furnace wall to increase. Therefore, in actual operation, the in-furnace gas flow distribution is controlled in consideration of the balance between the two.

By the way, such control of gas flow distribution is usually achieved by actually measuring the strength of the surrounding gas flow at the furnace mouth using a temperature standard (this is also an actual measurement of the center flow), and then determining its deviation in the circumferential direction and its relationship with the center gas flow. This is done by controlling the charging of coke and ores (direction and distribution amount control) according to the ratio. However, since it is the gas flow distribution from the morning glory section to the middle of the furnace chest that directly affects the reaction in the furnace, it goes without saying that it is preferable to also use actual measurement data of the surrounding gas flow at that position as a control element. Attempts have been made to measure the strength of gas flow around the reactor by installing a detection end in the middle to lower part of the reactor chest, but the thermal load on the detection end was too severe and it was difficult to obtain stable reliable data. It has not yet reached the point where it can be collected.

In addition, the heat load on the furnace wall is a particular problem in furnace condition management, and it is of course necessary to know the wear and tear of the furnace wall and know when to repair it in order to maintain the safety of actual furnace operation. However, at the same time, it is also necessary to actively prevent wear and tear by cooling the furnace walls and injecting milky refractories. In this case, in order to enhance the cooling effect, it is preferable to know not only the temperature fluctuation within the wall but also the surrounding gas flow distribution, and perform cooling control that also takes this situation into consideration. it is,
This is because temperature fluctuations within the wall propagate much later than the surrounding gas flow distribution, so controlling only by relying on the temperature fluctuations within the wall will not necessarily provide sufficient cooling efficiency. Therefore, from this point of view, there is a need to actually measure the strength of the gas flow around the area where the heat load on the furnace wall is relatively severe, that is, from the morning glory section to the furnace chest.

The present invention was made under these circumstances, and it is possible to improve the accuracy of gas control in the furnace by accurately estimating the strength of the surrounding gas flow from the upper part of the tuyere, especially from the morning glory part to the furnace chest, over a long period of time. The object of the present invention is to provide a method for estimating the strength of the surrounding gas flow, which can improve the reactivity in the furnace and also enable more efficient management of the furnace condition such as the heat load on the furnace wall.

However, the method for estimating the strength of the surrounding gas flow according to the present invention is to use a vertical temperature sensor that has three or more temperature sensing parts in the wall thickness direction and detects temperatures at different positions in the wall thickness direction. Embed an appropriate number in the circumferential refractory wall of the furnace,
The current inner surface position of the refractory wall is estimated from the correlation between the temperature fluctuation signal in the furnace wall and the temperature fluctuation signal in the furnace obtained by each temperature sensor, and the inner wall temperature and temperature corresponding to the estimated inner surface position are estimated. The furnace outer wall temperature corresponding to a point on the temperature sensor relatively close to the estimated inner surface position is determined, and the heat flow flowing between the estimated inner surface position and a point on the temperature sensor relatively close is determined for each temperature measurement. The gist of this method is to estimate quantitative changes in the gas flow strength on the furnace wall surface over time based on the changes in the average value over time.

The configuration and effects of the method of the present invention will be described below with reference to the drawings, and each component will be explained in order for ease of understanding. That is, in the method of the present invention, first, (1) a temperature sensor having three or more temperature sensing parts in the wall thickness direction and detecting temperatures at different positions in the wall thickness direction is installed in the circumferential direction of the refractory wall of the blast furnace; Bury an appropriate number of
Obtain temperature information from each temperature sensor. That is, FIG. 1 is a schematic explanatory diagram when the method of the present invention is applied to the middle part of the furnace chest of a blast furnace. A suitable number of them are buried in the circumferential direction of the blast furnace so as to penetrate through C and the stamp layer D and reach or penetrate almost the inner surface of the refractory wall W. In addition, if the sensor has at least 3 or more temperature sensing parts in the wall thickness direction, the model
Sensor B will be described as a preferable example of such a sensor, although its structure is not particularly limited. That is, FIG. 2 shows a partially cutaway perspective view of the sensor B, and FIG. 3 shows a developed cross-sectional view corresponding to FIG. 2. In these figures, reference numeral 1 denotes a jacket sheath tube that serves as a protective member for the entire sensor B. Reference numeral 2a denotes a sheath type thermocouple, and a pair of metal wires 4 and 4' exhibiting a thermoelectric effect are inserted through the thermocouple 2a, and the tips of the metal wires 4 and 4' serve as temperature measuring junctions, that is, temperature sensing parts P ₁ and P ₂ within the sheath. ,...P ₆ (hereinafter referred to as P when speaking representatively) constitutes. These temperature sensing parts P are configured to occupy different positions in the length direction, and in the figure, the positions in the length direction are approximately equal from the inside of the furnace (I side) to the shell side (O side). Change P ₁ , P ₂ ,…
…P ₆ has been established. Furthermore, at the tip of the temperature sensing part P,
A sheathed thermocouple 2b made of the same material as the sheathed thermocouple 2a is connected as a dummy (6 in the figure indicates a connection part). Further, 3 is a fire-resistant insulating material filled in the outer sheath tube 1, which has a thermal conductivity suitable for the fire-resistant wall characteristics in order to suppress the influence of thermal disturbances as much as possible. Therefore, it can be said that the temperature measurement performance of each temperature sensing part P in such a sensor B is sufficiently reliable in terms of accuracy and durability. If the sensor proposed by the present applicant, disclosed in Japanese Utility Model Application No. 57-81531, is used, it can be safely used for a long period of time regardless of wear and tear on the fireproof wall.

(2) Ascertain the current inner surface position of the refractory wall (including deposits), that is, the wall thickness l _w , from the correlation between the temperature fluctuation signal within the furnace wall obtained from each temperature sensing part and the temperature fluctuation signal inside the furnace. There have been several methods in the past, such as embedding temperature sensors in the furnace wall to measure the temperature at different positions in the wall thickness direction, and estimating the inner surface position of the refractory wall based on the temperature information. However, the following method (tentative name: Triggerless Bonus Analysis Method: Tokkosho
No. 57-51444) is a method that can estimate the inner surface position with extremely high accuracy, and it is particularly preferable to use this method in the present invention.

That is, Fig. 4 is an explanatory diagram of the trigger response analysis method, where P ₀ , P ₁ , P ₃ , ... indicate the temperature measurement points of sensor B, and T ₀ , T ₁ , T ₂ , T ₃ , ... indicate each temperature measurement point. Although it shows the temperature detected at the temperature measurement point, in this method, the absolute value of the detected temperature at each temperature measurement point is not used, but the analysis is performed as follows. That is, the fourth
The graph shown at the bottom of the figure shows temperature on the vertical axis and time on the horizontal axis. Curve T ₁ is the temporal change in detected temperature at temperature measurement point P ₁ , and curve T ₂ is the temperature measurement point P 1.
It represents the temporal change in the detected temperature at P ₂ (the same applies hereafter). The illustrated temperature change corresponds to the temperature change (instantaneous rise) at the T ₀ point shown on the outer right side of the vertical axis, and the temperature change at the T ₀ point is detected as a trigger signal.

Therefore, if we set the time when the trigger signal is detected as the zero point on the horizontal axis and track the momentary temperature changes at each temperature measurement point, the time when the detected temperature at each point peaks will be closer to the side of the steel shell C. Appears late.
This delay is called a delay time.

Since the spacing between each temperature measurement point is as designed when the sensor is embedded, l ₂ , l ₃ , l ₄ and l ₅ are known, and l ₁ is also known at the beginning of blast furnace operation. Changes in T ₀ can be detected directly by a sensor, and if you know in advance the time difference between the time when the temperature change occurs and the other detection end detected as a trigger signal, you can do the following: It is possible to perform zero point correction in the analysis described in . Now, the curve [X] in Figure 5 is obtained as a result of the zero point correction as described above, and P ₀ , P ₁ , P ₂ , ... indicate the respective temperature measurement points, and each temperature measurement point is This is obtained by plotting the delay time actually measured at the point. It can be seen that the intersection point P _x of the curve [X] with the horizontal axis is a zero point in this case, and the P ₀ point corresponds to the inner surface position of the fireproof wall.

Now, as the furnace continues to operate, the fireproof walls are worn out.
If the wear has exceeded not only the P ₀ point but also the P ₁ point, curve the horizontal axis position of each point from P ₂ to _{P 5} [X]
The solid line part of the curve [Y] is the delay time plotted in the same manner as in the case of P ₂
Extrapolate from the point to the chain line and find the intersection Py with the horizontal axis
get. This Py point corresponds to the point where the delay time is zero, and it is possible to infer where the innermost surface of the fireproof wall is located. Then, the wear progresses further, and as the wear progresses, the distance between points P ₃ to P ₅ and the innermost surface of the fireproof wall becomes shorter, so the delay time at each point becomes shorter, and the curve [Z] becomes even more It will shift towards the lower right. In this case as well, by extrapolating as shown by the chain line, it is possible to estimate the current zero point (ie, the innermost position).

(3) Find the wall temperature T _w corresponding to the wall inner surface position l _w estimated by (2): In other words, in Fig. 6, the _point (temperature
T _w ) may be obtained by extrapolating an n-dimensional curve using temperature measurement points T ₂ to T ₆ , or temperature measurement information at point P ₁ may be used. Furthermore, depending on the state of the wall inner surface position, the following method may be used. That is, as shown in Fig. 7, the wall temperature T _w ' can be estimated by reading the point on the n-dimensional extrapolated curve corresponding to the wall inner surface position l _w ', but the approximated curve approaches the actual measurement point _P2 . As the approximation rate increases, it is also possible to adopt a T _w ″ value that is slightly closer to the _P2 point, as shown in the figure.

(4) Temperature sensing part position l _s relatively close to the above wall inner surface position l _w
Determine the wall temperature T _s corresponding to: 6th and 7th
In the figure, l _s is, for example, P ₂ or P ₃ ,
The corresponding wall temperature T _s is the actual measurement point on the n-dimensional curve.
Determined as T ₂ or T ₃ . However, the estimated temperature T _{' 2 or} T' ₃ may be obtained by interpolating the n-th order equation for any point P' ₂ or P' ₃ that is distant from P 2 or P ₃ .

(5) Calculate the heat flow Q _ws flowing between the wall temperature T _w and T _s using the following formula: Q _ws = λ/l _w −l _s (T _w − T _s ) ... [However, λ is the sensor Thermal conductivity of B (kcal/
m・hr・℃) When using the T″ _w value as _Tw , use the following formula: Q _ws = λ/l _w −l _s (T′ _w −T _s ) ……′〕 (6 ) Perform the calculation operations (1) to (5) above for all sensors installed in the circumferential direction, and calculate (Q _ws ) ₁ ,
Find (Q _ws ) ₂ ,...

The heat flow obtained in this way (Q _ws ) ₁ , (Q _ws ) ₂ ,
After examining the correspondence between the changes in ... and the actual gas behavior in the reactor, it was found that they qualitatively match as shown below. It was confirmed that this method is an excellent method for estimating ambient gas flow. In other words, in actual measurement of gas behavior in the furnace, an appropriate number of so-called skin flow thermometers were installed in the circumferential direction at the furnace mouth, and the individual value or average value of each skin flow temperature detected by these thermometers was measured. By understanding changes over time,
We are making that estimate. Therefore, the present inventors also captured the average value of heat flow (Q _ws ) ₁ , (Q _ws ) ₂ , ..., that is, 1/n _o 〓 ⁿ⁼¹ (Q _ws ) _o , and calculated the above-mentioned skin flow. We investigated the correspondence with changes in temperature over time.
Figure 8 is a graph showing the change in skin flow temperature over time, and Figure 9 is a graph showing the change in heat flow average value over time, and it can be seen that the behavior of both changes over time is qualitatively consistent. . Therefore, by capturing the changes in the heat flow average value 1/n _o 〓 ⁿ⁼¹ (Q _ws ) _o mentioned above over time, it is possible to accurately estimate the surrounding gas flow from the upper part of the reactor chest to the lower part over a long period of time. I was convinced.

Also, Figure 10 shows the wall inner surface position (l _w ) obtained for each sensor in the calculation step (3) above.
The wall temperature (T _w ) ₁ , (T _w ) ₂ , … corresponding to ₁ , (l _w ) ₂ , …
This is a graph showing the change over time of the average value of 1/n _o 〓 ⁿ⁼¹ (T _w ) _o , but this change over time is also qualitatively similar to the change over time of the skin flow temperature shown in Figure 8. It was confirmed that they matched. However, in this case, the direct movement of heat inside the furnace inside the refractory wall, that is, the change in heat flow, is not taken into account, so there is a problem with accuracy, but depending on the furnace operating conditions, the average value of the inner wall temperature mentioned above may be It is also possible to estimate the surrounding gas flow based on changes over time and use the estimated value for controlling the gas in the reactor.

In the above, control using the average value was described, but since the average value corresponds well to the skin flow temperature, if each measured value in the circumferential direction is captured and controlled individually, it will also help eliminate uneven flow in the circumferential direction. This greatly contributes to improving the accuracy of reactor operation management.

It should be noted that the above implementation is merely a representative example and does not limit the present invention, and it goes without saying that implementation with appropriate modifications within the scope of the above-mentioned spirit is also included in the technical scope of the present invention. stomach. For example, the model, number of types, mounting position, number of temperature sensors, etc. can be changed as appropriate.
Furthermore, in the above explanation, the main focus was on blast furnaces as vertical furnaces, but it goes without saying that this is not limited to this. It can be well applied to high-temperature vertical furnaces.

Since the present invention is configured as described above, it is possible to accurately estimate the strength of the surrounding gas flow from the upper part of the tuyere, especially from the morning glory part to the furnace chest, for a long period of time. In addition to improving reactivity, it has become possible to operate a vertical furnace while managing furnace conditions such as furnace wall heat load more efficiently.

[Brief explanation of drawings]

Fig. 1 is a schematic explanatory diagram when the method of the present invention is applied to the middle part of the chest of a blast furnace, Fig. 2 is a partially cutaway perspective view of a temperature sensor used to carry out the method of the present invention, and Fig. 3 is a diagram corresponding to the developed cross section of Figure 2, Figure 4 is an explanatory diagram showing temperature changes on the inner surface of the refractory wall, Figure 5 is a graph showing the relationship between distance from the inner wall of the refractory and delay time, and Figures 6 and 7. 8 is a graph showing the change in the average skin flow temperature over time. FIG. 9 is a graph showing the change in the average heat flow value over time. FIG. 10 is a graph showing changes over time in the average value of each wall temperature corresponding to the wall inner surface position. B... Temperature sensor, W... Fireproof wall, P ₁ to _{P 6}
...Temperature sensing part.

Claims (1)

[Claims] 1. An appropriate number of temperature sensors having three or more temperature-sensing parts in the wall thickness direction and detecting temperatures at different positions in the wall thickness direction are buried in the circumferential direction in the refractory wall of the vertical furnace,
The current inner surface position of the refractory wall is estimated from the correlation between the temperature fluctuation signal inside the furnace wall obtained by the temperature sensor and the temperature fluctuation signal inside the furnace, and the furnace inner wall temperature corresponding to the estimated inner surface position and the estimated inner wall temperature are estimated. The furnace outer wall temperature corresponding to a point on the temperature sensor relatively close to the inner surface position is determined, and the heat flow flowing between the estimated inner surface position and the relatively nearby point on the temperature sensor is calculated for each temperature sensor. , a method for estimating the strength of a gas flow on the surface of a furnace wall in a vertical furnace, characterized by estimating the change over time of the gas flow on the surface of the furnace wall based on the change over time.