JPH0711018B2 - Blow-through prevention method in blast furnace operation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to blast furnace operation, and more particularly to prevention of blow-through in a blast furnace.

[Conventional technology]

When the pressure loss in the furnace locally increases during blast furnace operation and this becomes in a state of being balanced with the load of the charge, local stoppage of the charge, so-called hanging, occurs, and the load drops on the upper side of the hanging. Stops and creates space under the hanging as the furnace interior contents fall below the hanging. When this cavity becomes large to some extent, the charge on the outside of the hanging system slips into the cavity, which causes the local hanging process to collapse.
If the shelving is large and the collapse occurs suddenly, a large amount of the charged material moves locally and relatively quickly, causing the pressure loss inside the furnace to decrease locally and blowing up the gas inside the furnace upward. , At this time, the charge is blown up to the top of the furnace. This type of blow-up is called so-called blow-through, which disturbs the temperature distribution in the furnace and the distribution of the charged materials so that normal heat exchange reduction cannot be performed, disturbs the hot metal temperature, and in severe cases leads to cooling. Sometimes. Moreover, the temperature at the top of the furnace rises extremely, which poses a serious problem in maintaining the blast furnace equipment.

Japanese Examined Patent Publication No. 1-20203 discloses a static pressure on the inner surface of the furnace wall at a plurality of positions in the height direction of the blast furnace, and from these static pressures, a pressure loss from each measurement position to the top of the furnace is obtained. , The charge load from each measurement position to the furnace term is calculated, and the blowing air condition in the furnace is adjusted according to the ratio of the calculated pressure loss and the load of the furnace, and the above hanging (and the resulting Slip and blow-through) are proposed.

[Problems to be Solved by the Invention]

However, the load on the interior of the blast furnace depends on the properties of the sinter (grain size, T
Fe, reduction pulverization property, strength, etc., coke properties (grain size, reduction pulverization property, strength, etc.) and furnace conditions (blast furnace furnace wall wear: change in internal volume, change in friction resistance), The accuracy of the calculation (estimation) of the charge load at each point in the furnace is low, and therefore the accuracy of estimation of the possibility of rack hangings is low. As a result, in order to increase the reliability of restraint such as hanging from a shelf, the amount of air blow is excessively restrained and the stability of operation is disturbed. Loosening the control of the air flow increases the possibility of hanging on a shelf. Therefore, a more reliable blow-through prevention technique is desired.

It is an object of the present invention to increase the reliability of detection of the possibility of occurrence of blow-through and further improve the stability of blast furnace operation.

[Means for solving the problem]

In the first invention of the present application, the difference (ΔH) between the upper surface levels (Lj) of the blast furnace interior charges at a plurality of points in the furnace circumferential direction is the reference value (ΔH).
s) or higher and detect upper surface level (Lj)
It is detected whether the descent rate (dLj) at each position is equal to or higher than the reference value (dLs); each predetermined time interval Tets (10se) of the top gas temperature (Tej) of the plurality of riser tubes Zj at the top of the blast furnace.
The change amount (dTej) in c) and the temperature gradient (Taj) at a predetermined time interval Tetl (60 sec) are detected;
H) is a reference value (ΔHs) or more (DΔH = 1) and at least one of the descent rates (dLj) of the surface level (Lj) is a reference value (dLs) or more (DdL = 1), and the above-mentioned plurality of increases Fluctuation gradient (Taj) of the gas temperature (Tej) at the top of the pipe At least one of them is above the reference value Vp (Tajmax ≧ Vp) and at least one is below the reference value Vm (Tajmin ≦ Vn) and the above-mentioned furnace top When at least one of the gas temperatures shows a temperature drop change above the reference value (dTe) (DRd = 1 & DdT = 1), the amount of air blown into the blast furnace is reduced (27-29 in Fig. 2b).

In the second invention of the present application, a plurality of risers at the top of the blast furnace
Zet top gas temperature (Tej) at each predetermined time interval Tet
Change amount (dTej) of s (10 sec) and predetermined interval Tetl (60se
The temperature gradient (Taj) in c) is detected; the blast furnace circle in the charge just below the charge surface level above the blast furnace shaft (0.5m-1m below the minimum charge upper surface level during normal operation). Detecting each of the in-furnace gas temperatures (Tsj) at multiple points in the circumferential direction;
Top gas temperature (Tej) change gradient (Tj) of the plurality of risers Zj
at least one of aj) is above the reference value Vp (Tajmax ≥ Vp) and at least one is below the reference value Vm (Tajmin ≤ Vn), and at least one is below the reference value (dTe) (DRd
= 1 & DdT = 1), the temperature change in the furnace gas temperature (Tsj) at any of several positions in the circumferential direction of the blast furnace just below the surface of the charge on the upper part of the blast furnace shaft is the reference value (the past at the measurement position) Control upper limit of furnace gas temperature under normal operating conditions) (ΔTs _{1 to} ΔTs ₂ ) within the range of at least one of the multiple points (Tsmax) is greater than or equal to the reference value (Tss) (DT = 1) In addition, the amount of air blown into the blast furnace is reduced (Fig. 3b, 49-28-
29).

The symbols in parentheses indicate the symbols attached to the corresponding items of the embodiments of the present invention described below.

[Action]

Prior to the occurrence of the blow-through, abnormalities are caused in the descending state such as hanging from a shelf, and a local cavity is generated in the charging material. In such a state, the difference in the descending speed of the charging material in the circumferential direction of the blast furnace becomes large, and the height difference of the upper surface level Lj of the charging material becomes large.

By the way, if a cavity with a large size is generated in the charging material, the temperature distribution of the furnace top gas in the circumferential direction of the blast furnace is disturbed, and the temperature of the furnace top gas at a certain position in the circumferential direction of the blast furnace tends to decrease. The furnace top gas temperature tends to rise, and a circumferential furnace top gas temperature deviation occurs. However, when the blow-through occurs, contrary to the above, the furnace top gas temperature in a state where the furnace top gas temperature is relatively high drops significantly. That is, when the charge begins to collapse into the cavity, the gas flow in the furnace flowing through the cavity decreases and flows out from the surface of the charge in the vicinity of that part and flows into the furnace top rising pipe above that part. The temperature inside the furnace begins to drop from a relatively high temperature, and the furnace gas flow flowing at other positions increases and flows out from the surface of the charging material at that part, and the furnace top rises above that surface. The temperature of the gas flowing into the pipe rises from a relatively low state and rises sharply when it blows through.

In the 1st invention, paying attention to such a phenomenon, the upper surface level (Lj) of the blast furnace interior insert between the plural positions in the circumferential direction of the furnace
The difference (ΔH) is greater than or equal to the reference value (ΔHs),
Also, it is detected whether the descent rate (dLj) at each position of the surface level (lj) is higher than the reference value (dLs), and the gas temperature (Tej) at the top of the riser pipes at the top of the blast furnace is detected.
The change amount (dTej) within each predetermined time and the temperature change gradient are detected, and the difference (ΔH) in the upper surface level (Lj) is equal to or greater than the reference value (ΔHs) and the upper surface level (l
At least one of the descent rates (dLj) of j) is at least the reference value (dLs), and at least one of the temperature gradients of the top gas temperature (Tej) of the riser pipes is at the reference value Vp. Above (Tajmax ≥ Vp), and at least one other is the reference value Vn
Below (Tajmin ≦ Vn), and at least one of them is the reference value (dT
e) When the temperature drop change above is shown (DRd = 1 & DdT =
In 1), the amount of air blown into the blast furnace is reduced (27-2 in Fig. 2b).
9). That is, there is a large difference in height of the charge upper surface level Lj, and the rate of decrease of the charge upper surface Lj level is high.In addition, the furnace top gas temperature at a certain position in the blast furnace circumferential direction suddenly rises and other When the furnace top gas temperature at a position gradually rises or falls and the furnace top gas temperature at a certain position shows a temperature decrease fluctuation of a reference value or more, the air flow rate is reduced.

According to the first aspect of the present invention, the reliability of blowout prediction is high and the stability of operation is improved.

Also in the second invention, paying attention to the above-mentioned phenomenon, the change amount (dTej) and the temperature change gradient of each of the furnace top gas temperatures (Tej) of the plurality of riser tubes at the blast furnace top are detected, and It detects each of the in-furnace gas temperatures (Tsj) at multiple points in the blast furnace circumferential direction immediately below the upper surface ST of the charge, and also detects the temperature change amount at each position from the detected values, At least one of the furnace top gas temperature (Tej) is the standard value V
p or more (dTmax ≥ Vp), and at least one other is the reference value
Vn or less (dTmin ≥ Vn), and at least one of them is the reference value (dT
e) More than a decrease (DRd = 1 & DdT = 1), and in addition, the furnace gas temperature (Ts
The temperature change of j) within a predetermined time is the reference value (ΔTs ₁ ~ Δ
Within the range of Ts ₂ ), when at least one of the plurality of points (Tsmax) exceeds the reference value (Tss) (DT = 1), the amount of air blown into the blast furnace is reduced (Fig. 2b). 49-28-29). That is, the temperature of the top gas at a certain position in the circumferential direction of the blast furnace sharply decreases, the temperature of the top gas at another position gradually increases or decreases, and the temperature of the top gas at a position is equal to or higher than the reference value. In addition, the air flow rate is reduced when the skin flow gas temperature fluctuates with time.

According to the second aspect of the present invention, since the blow-through prediction is performed by the combination of the abnormal change detection of the temporal change amount of the furnace top gas temperature and the skin flow gas temperature in the circumferential direction, the reliability thereof is high,
Operation stability is improved.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[First Embodiment of the Invention] FIG. 1 shows an outline of an apparatus for carrying out the present invention. In this embodiment, four thermometers Tkj (skin flow thermometers) for detecting the in-furnace gas temperature Tej just below the charging surface ST at the upper stage of the shaft are installed at equal intervals in the circumferential direction of the blast furnace. , A temperature detection signal indicating the furnace gas temperature Tsj just below the upper surface level Lj of the charge is given to the input / output interface (input / output signal processing circuit) SPC. A sounding device S is installed above the shaft part, and this detects the surface level (height) Lj of the upper surface of the charge at four points that are set at equal intervals in the circumferential direction, and inputs the surface level signal. Give to the output interface SPC. At the top of the blast furnace, there are four rising pipes Zj, which are also equipped with gas thermometers Tzj. These are rising pipes Zj.
The temperature Tej of the furnace top gas that rises is measured, and a signal indicating the temperature of the furnace top gas is given to the input / output interface SPC.

Numbers 1 to 4 are assigned to the respective riser pipes Zj, and j of the furnace top gas temperature Tej that rises each riser pipe Zj is the riser pipe number number (j = 1 to 1).
4), that is, the furnace top gas temperature Tej of the rising pipe Zj indicates the furnace top gas temperature of the rising pipe of No. j, the skin flow gas temperature Tsj measurement position (circumferential direction j = 1 to 4), and each of the charging upper surface level Lj measurement positions (circumferential direction j = 1 to 4) (circumferential position j)
Is on each vertical plane that includes the vertical axis of the blast furnace and the central axis of each riser Zj.

That is, if the furnace gas rises symmetrically with respect to the blast furnace axis, Tsj is the skin flow gas temperature that rises toward the riser No. j in the charge immediately below the charge surface, Lj.
Is the surface level of the charging surface closest to the riser No.j, and Tej is the temperature of the top gas flowing in the riser No.j.

The sounding device S measures the surface level on the charged material at four points in the circumferential direction and inputs it to the input / output interface SPC, and latches the measured data there at a cycle of 10 seconds. The skin flow thermometer Tkj and the furnace top thermometer Tzj for measuring the gas temperature in the rising pipe Zj respectively input the temperature detection data to the input / output interface SPC and latch it there at a cycle of 2 seconds and 5 seconds.

The input / output interface SPC edits and holds all the latest data of the given measurement data in a set of 10-second data frames, and when the computer CMR requests data, the set of data frames is stored. Transfer to computer CMR.

The computer CMR requests the measurement data from the input / output interface SPC at a cycle of 10 seconds, receives a set of data frames, extracts the required data from the data frames, and executes the blowout prediction process described later to generate blowouts. Judge the possibility, create the blow control data corresponding to the judgment result,
When requesting measurement data, the blow control data is output to the input / output interface SPC together with the transfer instruction signal. The input / output interface SPC sends the air blow control data from the computer CMR to the air blower BRA.

2a and 2b show the contents of the blow-through prediction process of the computer CMR.

First, referring to FIG. 2a, when starting this process, the computer CMR first starts a 10-second timer and waits for 10 seconds. (Steps 1 and 2; in parentheses, the word step is omitted and only numbers are shown). When 10 seconds have passed, the 10-second timer is restarted (3) and the measurement data is read from the input / output interface SPC (4).

Next, the computer CMR reads the surface level data Lj from the latest read measurement data (5) and extracts the maximum value Lmax and the minimum value Lmin from the surface level data Lj (6,
7) Calculate the deviation ΔH between the maximum value Lmax and the minimum value Lmin (8), check if the deviation ΔH is the reference value ΔHs (0.5m) or more (9), and judge that it is the determination data register DΔH "1" is written in (10), otherwise, the judgment data register DΔH is cleared (11).

Computer CMR then updates the latest surface level readings Lj and 1
The surface level drop dLj for the past 10 seconds is calculated by referring to the surface level measurement value 0 seconds before (the previous input value) (13). Then, it is checked whether the amount dLj of drop is equal to or greater than the reference value dLs (1.0 m) (14), and if so, write "1" to the judgment data register DdL (15), and if not, the judgment data register Clear DdL (16).

Reference is now made to FIG. 2b. Next, the computer CMR reads the furnace top gas temperature Tej of the rising pipe Zj from the measurement data at intervals of 10 seconds (17), and writes it in the row register MTRj together with the read data six times before this time (18). On the other hand, based on the previously read measurement data of the furnace top gas temperature Tej that was read this time, the decrease fluctuation amount dTej of each furnace top gas temperature during 10 seconds
To calculate. Then, the calculated temperature drop fluctuation amount is calculated as dT
It is checked whether ej is equal to or higher than the reference value dTe (20 ° C) (whether there is an abnormal change) (19). If there is an abnormal change, "1" is written to the judgment register DdT (20), and if not, the judgment register DdT is cleared (21).

The computer CMR then performs the data (6
The temperature change gradient (dTj) at each position in the circumferential direction of the blast furnace was calculated from the furnace gas temperature (Tej) input every 10 seconds during 0 seconds by the regression equation (22a), and the highest value among the calculated values
dTjmaxt The lowest value dTjmin is extracted (22,23), and the highest value dTjm
Check if ax is greater than or equal to the reference value Vp (7 ° C / min) and if the lowest value dTjmin is less than or equal to the reference value Vn (3 ° C / min) (24,25). At this time (the furnace top gas temperature rises sharply in one riser pipe and the furnace top gas temperature rises or falls gently in the other riser pipe), "1" is written to the judgment register DRd (26), When at least one does not exist, the judgment register DRd is cleared (2
7).

Next, the computer CMR checks the contents of the judgment registers DΔH, DdL, DdT and DRd (28) and judges that there is a possibility of blow-through if the contents are all "1".
That is, the difference in the circumferential direction of the charge surface level is equal to or greater than the reference value, the surface level variation is equal to or greater than the reference value at a certain position in the circumferential direction, the decrease variation in the furnace top gas temperature of a certain riser is equal to or greater than the reference value, and , If the temperature of one furnace top gas in the riser rises and the temperature of the other gas falls simultaneously, it is determined that there is a possibility of blow-through.

If the computer CMR determines that there is a possibility of a void,
Generates air volume reduction instruction data for blow-through prevention and gives this to the blower BRA via the input / output interface SPC (2
9) In addition, the display on the CRT display DIS is updated to show the current measurement data, judgment data, air flow rate data of the air blower and cautions for blown air (30).

When predicting the blow-through as described above, the blow-through limit index F, RIV: Effective internal volume of blast furnace, OC: ORE / COKE (-), ρc: COKE bulk density (t / m ³ ), ρo: ORE bulk density (t / m ³ ), BV: Air flow rate (Nm ³ / min) ), TP: Furnace top pressure (kg / cm ² ), S: Furnace average cross-sectional area (m ² ) with blow-through prevention values, and calculate the air flow rate BV by back-calculation. From the calculated air flow rate BV Further, the value for increasing the safety is subtracted, and the air flow rate data indicating the residual value is given to the air blower BRA (29).

When it is not judged that the blow-through should be taken, a signal for maintaining the current state is given to the blower device BRA (31), and the CRT display DIS
The current measurement data, the judgment data, the air flow rate data of the air blower, and the absence of blow-through are displayed on the display (32).

[Second Embodiment of the Invention] The processing operation of the computer CMR of this embodiment is shown in FIGS. 3a and 3c. In this embodiment, the computer CMR performs the following processing every 10 seconds.

First, refer to FIG. 3a. The computer CMR first reads the latest furnace top gas temperature Tej from the measurement data at intervals of 10 seconds (1 to 4), and writes it in the row register MTRj together with the read data up to 6 times before this time (18). On the other hand, the decrease fluctuation amount dTej of each furnace top gas temperature during 10 seconds is calculated from the measurement data of the furnace top gas temperature Tej read this time and the measurement data read last time. And whether the calculated temperature drop variation dTej is more than the reference value dTe (20 ℃) (whether there is an abnormal variation)
Check (19). Write "1" to the judgment register DdT if there is an abnormal decrease fluctuation (20), and if there is not, judge the register D
Clear dT (21). The computer CMR then calculates the temperature change gradient (dTj) at each position in the circumferential direction of the blast furnace from the regression equation from the data in the row register MTRj (furnace gas temperature Tej input every 10 seconds during 60 seconds). (22a),
The maximum value dTmax and the minimum value dTmin among these calculated values are extracted (22,23), and it is checked whether the maximum value dTjmax is higher than the reference value Vp (7 ° C / min) and the lowest value dTmin is the reference value. Vn (3
(24 ° C / min) or less (24,25), and when both are present (one riser pipe Zj raises the top gas temperature and another riser Zj changes the top gas temperature To decrease), "1" is written in the judgment register DRd (26), and when there is no one, the judgment register DRd is cleared (27).

Next, the computer CMR displays the skin flow gas temperature input at 2 second intervals every 10 seconds.
Read Tsj (41).

Reference is now made to FIG. 3b. The computer CMR extracts the maximum value Tsmax and the minimum value Tsmin from each of the five measured data of the read temperature data Tsj, j = 1 to 4 (42,43), and their temperature difference (temperature change amount). ΔTsj = Tsjmax-Tsjmin is calculated (44), and the temperature difference ΔTsj is the reference value ΔTs ₁ (10 ° C) to ΔTs ₂
Within the range of (20 ℃) (whether the skin flow gas temperature fluctuates), and the maximum value Tsjmax is the reference value Tss (300
It is checked whether the temperature is higher than (° C) or not (45, 46), and if so, "1" is written in the judgment register DT (47), and if not, the judgment register DT is cleared (48).

The computer CMR then determines the decision registers DdT, DRd and DT.
Check the contents of (49), and if all of them are "1", it is judged that there is a possibility of a void. That is, the decrease fluctuation of the furnace top gas temperature of a certain rising pipe Zj is not less than the reference value, the temperature change gradient of one furnace top gas temperature of the rising pipe Zj is not less than the reference value, and the temperature of the other furnace top gas temperature is The change gradient is below the reference value and the skin flow gas temperature
Change amount of Tsj If abnormal at any position in the circumferential direction and the skin flow gas temperature Tsj at a certain position is abnormally high at the same time, it is determined that there is a possibility of blow-through.

If the computer CMR determines that there is a possibility of a void,
Generates air volume reduction instruction data for blow-through prevention and gives this to the blower BRA via the input / output interface SPC (2
9) In addition, the display on the CRT display DIS is updated to show the current measurement data, judgment data, air flow rate data of the air blower, and cautions for blown air. (30).

When the blow-through is not predicted, the current status maintenance signal at that time is given to the blower device BRA (31), and the CRT display DIS
The current measurement data, the judgment data, the air flow rate data of the air blower, and the absence of blow-through are displayed (32).

〔The invention's effect〕

According to the first aspect of the present invention, since the blow-through prediction is performed by adding the detection of the variation of the furnace top gas temperature in the circumferential direction in addition to the detection of the fluctuation of the charge surface level, the reliability is high and the operation stability is improved. .

According to the second aspect of the present invention, since the blow-through prediction is performed by adding the circumferential variation of the furnace top gas temperature to the circumferential variation of the skin flow gas temperature, the reliability is high and the operation is stable. The property is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an outline of an apparatus for carrying out the invention of the present application. 2a and 2b are flowcharts showing the processing operation of the computer CMR shown in FIG. 1 according to the first embodiment of the present application. 3a and 3b are flowcharts showing the processing operation of the computer CMR according to the second embodiment of the present application.

Claims (2)

[Claims] 1. A method for detecting whether or not a difference between upper surface levels at a plurality of points in a furnace circumferential direction of an blast furnace interior charge is higher than a reference value and detecting whether the descending speed of each position of the upper surface level is a reference value or more. Detecting the amount of change and temperature change gradient of the furnace top gas temperature of multiple risers at the top of the blast furnace within a predetermined time, the upper surface level difference at multiple points in the furnace circumferential direction is above the reference value and the upper surface At least one of the descending speeds of each level is equal to or higher than the reference value, at least one of the furnace top gas temperature change gradients of the plurality of riser pipes is equal to or higher than the reference value, and at least one other is equal to or lower than the reference value, and , At least when one of the furnace top gas temperatures shows a temperature drop above the reference value, reduce the amount of air blown into the blast furnace,
Blow-through prevention method in blast furnace operation. 2. A plurality of points in the circumferential direction of the blast furnace just below the surface of the charge above the shaft of the blast furnace are detected by detecting the amount of change and the temperature change gradient of the furnace top gas temperature of a plurality of rising pipes at the top of the blast furnace. Detecting each of the furnace gas temperature, at least one of the furnace top gas temperature change gradient of the plurality of risers is a reference value or more, other at least one is below the reference value,
In addition, at least one of the furnace top gas temperatures shows a temperature drop above the reference value, and the gas temperature in the furnace at any of the multiple points in the circumferential direction of the blast furnace immediately below the surface of the charge at the upper part of the blast furnace is within the predetermined time. When the temperature change in is within the reference value range and at least one of the plurality of points is the reference value or more, the amount of air blown into the blast furnace is reduced. , Blow through prevention method in blast furnace operation.