JPH04173909A - Method for preventing blowby in blast furnace operation - Google Patents

Abstract

PURPOSE:To improve detective reliability to possibility of blowby development and to improve stability of blast furnace operation by comparing variation of surface level and dropping velocity of charged material in the blast furnace, variance and variable gradient, etc., of furnace gas temps. with the reference values. CONSTITUTION:In the blast furnace during operation, the surface level of charged material in the blast furnace is measured with a sounding device S. Further, the furnace gas temps. in plural riser Zj, are measured with furnace top thermometer Tzj. These measured values are inputted to a computer CMR through an input/output interface SPC. Then, it is detected whether the surface level of charged material at plural points in circumferential direction of the furnace and dropping velocity at each position are the reference values or more. Further, the variance of furnace gas temp. within the prescribed time and temp. variation gradient thereof, are detected. Successively, when the above level difference shows the reference value or more, and at least one of the dropping velocities shows the reference value or more and at least one of the variation gradients of the above furnace gas temps. shows the reference value or lower and at least one of the furnace gas temps. shows the reference value or more and at least one of the furnace gas temps. shows temp. drop larger than or equal to the reference value, the blasting rate into the blast furnace is reduced to prevent the blowby.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to blast furnace operations, and in particular to the prevention of blast furnace blowouts.

[Conventional technology]

During blast furnace operation, when the pressure loss inside the furnace increases locally and becomes balanced with the charge load, the charge locally stands still, so-called shelf suspension, and above the shelf suspension, the charge drops. , and as the contents of the furnace below the shelf hanger fall, a space is created under the shelf hanger. When this cavity becomes large to a certain extent, the charge outside the shelf suspension slips into the cavity, causing the local shelf suspension to collapse.

If the shelf hangs large and collapses rapidly, the pressure drop in the furnace decreases locally due to the relatively fast local movement of a large amount of charge, and the gas in the furnace blows upward. At this time, the charge is blown up to the top of the furnace. This type of blow-up is called blow-by, and it disturbs the temperature distribution in the furnace and the charge distribution, preventing normal heat exchange, which disturbs the temperature of the hot metal, and in severe cases can cause cooling. It may come.

Moreover, since the temperature at the top of the furnace rises extremely, this poses a major problem in terms of maintenance of the blast furnace equipment.

Japanese Patent Publication No. 1-20203 discloses that the static pressure on the inner surface of the furnace wall at multiple positions in the height direction of the blast furnace is measured, and from these static pressures, the pressure loss from each measurement position to the top of the furnace is determined. , find the charge load from each measurement position to the top of the furnace, and set the air blowing conditions in the furnace in accordance with the ratio of pressure loss and charge load found! Techniques have been presented to prevent the above-mentioned shelf suspension (and the resulting slippage and blow-through).

[Problem to be solved by the invention]

However, the load of the blast furnace contents depends on the properties of the sintered ore (particle size,
TFe, reduction powdering properties 9 strength, etc.), coke properties (particle size, reduction powdering properties 9 strength, etc.), and furnace conditions (blast furnace wall wear: changes in internal volume, changes in frictional resistance). The accuracy of calculating (estimating) the charge load at each point in the furnace is low, and therefore the accuracy of estimating the possibility of shelving, etc. occurring is low. As a result, in order to increase the reliability of suppressing shelf hanging, etc., the amount of air blown must be excessively suppressed, which disturbs the stability of operation.

Relaxing the restriction on air flow increases the possibility of shelf hanging, etc. Therefore, an even more reliable technique for preventing stairwells is desired.

An object of the present invention is to increase the reliability of detecting the possibility of occurrence of blow-through, thereby increasing the stability of blast furnace operation.

[Means to solve the problem]

In the first invention of the present application, the difference (ΔH) in the upper surface level (Li) at multiple points in the circumferential direction of the blast furnace contents is set to a reference value (ΔH).
Is) or above is detected and the upper surface level (L
l) The descent speed (dLj) at each position is the reference value (d
Ls) or above; detect the amount of change (dTej) in each predetermined time interval Te+5 (10 sec) of the furnace top gas temperature (Tei) of a plurality of riser pipes zH at the top of the blast furnace furnace and the predetermined time interval Tetl (60 sec). ) temperature gradient (Tai
) is detected.

The difference in the upper surface level (ΔH) is equal to or higher than the reference value (ΔHs) (DΔH; ]), and at least one of the lowering speeds (dLj) of the upper surface level (Lj) is equal to the reference value (dLs).
) or more (DdL=1), at least one layer of the change gradient (Tii) of the furnace top gas temperature (Tei) of the plurality of riser tubes is equal to or higher than the reference value Vp (Tai+max≧Vp), and at least one other layer is the reference value Value V+a or less (Tiimin≦Vn)
and at least one layer of the furnace top gas temperature is at a reference value (dTe
) or more (DRd=I &
DdT=1), reduce the amount of air blown into the blast furnace (2nd b).
27-29 in the figure).

In the second invention of the present application, the amount of change (dTei) in each predetermined time interval Tets (10 sec) of the furnace top gas temperature (Tei) of the plurality of riser pipes zz at the top of the blast furnace and the predetermined interval Te ) is detected, and the temperature gradient (Tai) at the top of the blast furnace shaft is detected, and the temperature gradient (Tai) at
0.5 below the minimum charge surface level during normal operation
Detect each of the furnace gas temperatures (Tsi) at a plurality of points in the blast furnace circumferential direction within the charge of 200 m to 1lII below:
) at least one layer is equal to or higher than the standard value Vp (T month maw≧Vp
) and at least one other layer is below the reference value Vm (Tajm
in≦Vn), and at least one layer has a temperature drop of more than the reference value (dTe) DRd=1 & DdT=1), at any one of multiple points in the circumferential direction of the blast furnace immediately below the surface of the charge at the top of the blast furnace shaft. The temperature change in the furnace gas temperature (Tsi) within a predetermined time is the reference value (control upper limit value of the furnace gas temperature in the past normal operating state at the measurement position) (ΔTsl
~ΔTsz) at least one layer of the plurality of points (Ts
max) is equal to or higher than the reference value (Tss) (DT=1), the amount of air blown into the blast furnace is reduced (see 49 in Figure 3b).
-28-29).

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

[Effect]

Before the occurrence of blow-through, an abnormality occurs in the descending state such as hanging on a shelf, and a local cavity is created in the charged material.

In such a state, the difference in the descending speed of the charge increases in the circumferential direction of the blast furnace, and the height difference in the top surface level LJ of the charge increases.

By the way, when a cavity of considerable size occurs in the charge, the top gas temperature distribution in the circumferential direction of the blast furnace is disturbed, and the top gas temperature at a certain position in the circumferential direction of the blast furnace tends to decrease while that at other positions. The furnace top gas temperature tends to rise, and a circumferential furnace top gas temperature deviation occurs.

However, when reaching the blow-through, contrary to the above, the furnace top gas temperature, which is relatively high, decreases significantly.

That is, when the charge begins to collapse into the cavity, the flow of furnace gas flowing through the cavity decreases and flows out from the charge surface near that area and into the furnace top riser above that area. The temperature of the gas in the furnace begins to decrease from a relatively high state, and the flow of gas in the furnace flowing through other locations increases, flowing out from the surface of the charge in that area and rising to the top of the furnace above the surface. The temperature of the gas flowing into the furnace starts to rise from a relatively low state and rises rapidly when it reaches the atrium.

The first invention focuses on such a phenomenon, and the upper surface level (L) of the contents in the blast furnace between multiple points in the circumferential direction.
) is greater than or equal to the reference value (Δ)Is), and whether the descending speed (dLi) at each position of the surface level (11) is greater than or equal to the reference value (dLs). Furthermore, the amount of change (d
Tei) and temperature change gradient are detected, and the upper surface level (Li
) difference (ΔH) is equal to or higher than the standard value (80 s) and the respective lowering speeds (
dLi) is above the reference value (dLs), and at least one layer of the temperature change gradient of the furnace top gas temperature (Tej) of the plurality of risers is above the reference value Vp (Taimix
≧VP), and at least one other layer is below the reference value Vn (
Taimin≦Vn), and at least one layer is equal to the reference value (d
When the temperature decreases by more than Te) (DRd=I
&DdT=1), reduce the amount of air blown into the blast furnace (second
27-29 in Figure b). In other words, the difference in height between the level tonnage on the top surface of the charge is large and the rate of descent of the top level tonnage on the top surface of the charge is high. When the furnace top gas temperature at a certain position gradually increases or decreases, and the furnace top gas temperature at a certain position shows a temperature decrease fluctuation greater than a reference value, the air flow rate is reduced.

According to this first invention, the prediction reliability of the atrium is high, and the stability of the operation is improved.

The second invention also focuses on the above-mentioned phenomenon, and detects the amount of change (dTei) and temperature change gradient of the top gas temperature (Tej) of a plurality of riser pipes at the top of the blast furnace, and detects the temperature change gradient at the top of the blast furnace shaft. The furnace gas temperature (Tsj) at multiple points in the circumferential direction of the blast furnace directly below the top surface ST of the charge is detected, and the amount of temperature change at each position is detected from the detected value, and the At least one layer of the furnace top gas temperature (Tej) is equal to or higher than the standard value 12 (dT@ax≧vp), and at least one other layer is equal to or lower than the standard value v11 (dTmin
≧Vn), and at least one layer decreases by more than the reference value (dTe) DRd=I & DdT=1), and in addition, the furnace gas temperature (T
sj) within a predetermined time is the reference value (ΔTs
1-ΔTs2), at least one layer of the plurality of points (
Tsmaz) has exceeded the standard value (Tss) (DT=
1) Reduce the amount of air blown into the blast furnace (49-28-29 in Figure 2b). In other words, the furnace top gas temperature at a certain position in the circumferential direction of the blast furnace suddenly decreases, the furnace top gas temperature at other positions gradually increases or decreases, and the furnace top gas temperature at a certain position exceeds the reference value. In addition, the amount of air blown is reduced when the skin flow gas temperature changes over time.

According to this second invention, the atrium is predicted by a combination of abnormality detection of the amount of change over time in the circumferential direction of the furnace top gas temperature and the skin flow gas temperature, so its reliability is high;
Operational 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.

[Embodiment of the first invention] FIG. 1 shows an outline of an apparatus for implementing the present invention.

In this embodiment, four thermometers Tki are used to detect the furnace gas temperature Te just below the charge surface ST in the upper part of the shaft.
Skin flow thermometers (skin flow thermometers) are installed at equal intervals in the circumferential direction of the blast furnace. processing circuit) is given to the SPC. A sounding device S is installed above the shaft, which detects the surface level (height) Lj of the upper surface of the charge at four points equally spaced in the circumferential direction, and inputs surface level signals. to the output interface SPC. There are four riser pipes Zj at the top of the blast furnace, and these are also equipped with gas thermometers Tzz, which measure the top gas temperature Tej rising through the riser pipes Zj and send a signal indicating the top gas temperature. is given to the input/output interface SPC.

Each ascending pipe ZJ is numbered 1 to 4, and each rising pipe Z
J of the furnace top gas temperature Tej that increases j is the riser pipe No
, a number (j=1 to 4), that is, the furnace top gas temperature 1Tej of the riser pipe ZJ is N. , indicates the furnace top gas temperature of the riser pipe of J, skin flow gas temperature Tsj measurement position (circumferential direction" = 1 to 4), charge top surface level LJ measurement position (circumferential direction") =1 to 4) (circumferential position j) is on each vertical plane including the vertical axis of the blast furnace and the central axis of each riser pipe ZJ.

That is, assuming that the gas in the furnace rises completely symmetrically with respect to the blast furnace axis, Tsj is the skin flow gas temperature rising in the charge just below the surface of the charge toward riser pipe No. The surface level of the charge surface closest to No,j, Tej is the temperature of the top gas flowing in the riser pipe No,j.

The sounding device S measures the surface level of the charge at four points in the circumferential direction, inputs the measured data to the input/output interface SPC, and latches the measured data therein at a cycle of 10 seconds.

The skin flow thermometer TkJ and the furnace top thermometer Tzz that measures the gas temperature in the riser pipe ZJ each input temperature detection data to the input/output interface SPC and output the data there.
sec period, latches at 5 sec period.

The input/output interface SPC edits and holds all the latest measurement data given into l sets of data frames at loset intervals, and the computer CM
When R requests data, it transfers the set of data frames to computer CMR.

The computer CMR requests measurement data from the input/output interface SPC at the loset period, receives one set of data frames, extracts the required data from it, and performs a prediction process to describe the atrium. It determines the possibility of occurrence, creates ventilation control data corresponding to the determination result, and outputs the ventilation control data to the input/output interface SPC together with a transfer instruction signal when requesting measurement data. The input/output interface SPC sends air blow control data from the computer CMR to the air blower BRA.

FIGS. 2a and 2b show the contents of the prediction process in the open space of the computer CMR.

First, referring to Figure 2a, when starting this process, the computer CMR first starts a 10 second timer and waits for IO seconds to elapse (steps 1 and 2; hereinafter, the word step is omitted in parentheses and only numbers are used). ). 1
When 0 seconds elapse, restart the 10 second timer 3).
Read the measurement data from the input/output interface SPC (4).

Next, the computer CMR reads the surface level data LJ from the latest measurement data read (5), extracts the maximum value Lmax and minimum value Lmin from the surface level data LI (6.7), and extracts the maximum value Lmax. Calculate the deviation ΔH between the minimum value Lmin and the minimum value Lmin (8).
, 5m) or more (9), and if so, write "1" to the judgment data register DΔH (10
), otherwise the judgment data register DΔH is cleared (11).

The computer CMR then displays the latest surface level measurements L
Surface level measurement value 1 and 10 seconds ago (previous input value)
With reference to, the surface level fall amount d during the past 10 seconds
Calculate L1 (13). Then, check whether the descent amount dLJ is greater than or equal to the reference value dLs (1,0 m) (1,0 m).
4) If so, write "rl" in the judgment data register DdL.
(15), and if not, clear the judgment data register DdL (16).

Reference is now made to Figure 2b. Computer CMR then
Read the furnace top gas temperature Te of the riser pipe Z from the measurement data at 10-sec intervals (17) and write it to the row register MTRj along with the read data up to six times before this time (+8).
.

On the other hand, based on the measurement data of the furnace top gas temperature Tei read this time and the measurement data read last time, the amount of decrease dTe j of each furnace top gas temperature during 10 sec is calculated.

Then, it is checked whether the temperature drop fluctuation amount dTe i calculated this time is greater than or equal to the reference value dTe (20° C.) (whether there is an abnormal fluctuation) (19). If there is an abnormal decrease fluctuation, "1" is written in the determination register DdT (20), and if there is no abnormality, the determination register DdT is cleared (21).

Next, the computer CMR calculates the temperature change gradient (dTi) at each position in the circumferential direction of the blast furnace using a regression formula from the data in the row register MTR (furnace gas temperature Tej input every 10 seconds during 60 seconds). 22a)
, the highest value dTjmax and the lowest value dTi among these calculated values
Extract min (22, 23) and find the highest value dTjmax
Check whether the minimum value dTimin is equal to or greater than the reference value vp (7℃/min) and check whether the minimum value dTimin is less than or equal to the reference value Vn (3℃/min) (24°25). (When the furnace top gas temperature increases rapidly in one riser pipe and the furnace top gas temperature gradually increases or decreases in the other riser pipe), write rlJ to the determination register DRd (2
6), if at least one is missing, the judgment register DR
(27) Computer CMR then clears determination registers DΔH and DdL.

The contents of DdT and DRd are checked (28), and if the contents are all "!", it is determined that there is a possibility of a blowout. In other words, the difference in the circumferential direction of the charge surface level is greater than or equal to the reference value, the surface level variation is greater than or equal to the reference value at a certain position in the circumferential direction, the decreasing variation in the furnace top gas temperature of a certain riser is greater than or equal to the reference value, and If the temperature of the top gas in one of the riser pipes increases and the temperature of the other gas decreases at the same time, it is determined that there is a possibility of blow-through.

When determining that there is a possibility of an atrium blowout, the computer CMR generates air volume reduction instruction data to prevent an atrium and sends this to the blower BRA via the input/output interface SPc (29), and displays the information on the CRT display DI3. , the current measurement data, judgment data, air volume data of the blower device, and atrium will be updated to indicate caution (3)
0).

In addition, when the atrium is predicted as described above, the atrium is the limit index F, (a BY-TP) X S X 10 RIM: Effective internal volume of the blast furnace.

QC: ORE/C0KE (-).

Pc: C0KB bulk density (+/m3).

ρo2ORE bulk density (1/m3).

Bv: Air flow rate (lh3/min).

TP: Furnace top pressure (Kg/cm2).

S: For the average cross-sectional area inside the furnace (I112), give a value for preventing the blowout, calculate the air volume BY by back calculation, and subtract the value to further increase safety from the calculated air volume BY. Air blowing amount data showing the air blowing device B
Give to RA (29).

If it is determined that the atrium does not require action, a signal to maintain the current state is given to the blower BRA (31), and the display on the CRT display DI3 is changed to display the current measurement data, judgment data, airflow amount data of the blower, and the atrium. It is displayed that there is no such thing (32).

[Embodiment of the second 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.

Reference is first made to FIG. 3a. The computer CMR first reads out the latest furnace top gas temperature Tej from the measurement data at 10 sec intervals (1 to 4), and writes it into the row register MTRj together with the read data up to six times before this time (18). - On the other hand, based on the measurement data of the furnace top gas temperature Tei read this time and the measurement data read last time, the amount of decrease dTe i of each furnace top gas temperature during 10 seconds is calculated. Then, the temperature drop fluctuation amount dTe i calculated this time is the reference value dTe(2
0°C) or higher (checks the potency with abnormal fluctuation (19). If there is abnormal lowering fluctuation, judgment register DdT
Write “1” to (20) and determine that there is no register DdT.
Clear (21). Computer CMR then reads the data in row register MTRj (for 60 seconds, l
From the furnace top gas temperature Te1) input every 0 sec, the temperature change gradient (
22a), extract the maximum value dTmax and minimum value dTmin from the calculated values (22, 23
), check whether the highest value dTioax is greater than or equal to the reference value vp (7°C/min), and check whether the lowest value dTmin is less than or equal to the reference value Vn (3°C/min) (24
, 25), when both are present (the top gas temperature increases in one riser pipe zl and the furnace top gas temperature decreases in the other riser pipe 2), rlJ is written in the determination register DRd ( 26), if one is missing, the judgment register DRd
Clear (27).

Next, the computer CMR reads out the skin flow gas temperature data Tsi every 10 seconds based on the skin flow gas temperature inputted at intervals of 2 seconds (41).

Reference is now made to Figure 3b. The computer CMR extracts the highest value Tsmax and lowest value Tsrnjn from each of the five measured data for each of the read temperature data Tsj, j=1 to 4 (42, 43), and calculates the temperature difference (amount of temperature change) between them. ΔT
Calculate s 1=Ts jmax-Ts 1m1n4
4), the temperature difference ΔTsi is the reference value ΔTs, (10°C) - Δ
Check whether it is within the range of TS2 (20°C) (is there a fluctuation in the skin flow gas temperature) and whether the maximum value Tsiωax is greater than or equal to the reference value Tss (300°C)45.46). If there is, “1” is written in the judgment register DT.
is written (47), and the determination register DT is cleared (48).

The computer CMR then registers the decision registers DdT, D
The contents of Rd and DT are checked (49), and if they are all "1", it is determined that there is a possibility of a blowout. That is, the decreasing fluctuation of the furnace top gas temperature of a certain riser pipe Z is above the reference value, the temperature change gradient of the furnace top gas temperature of one riser pipe ZH is above the reference value, and the change in the furnace top gas temperature of the other riser pipe ZH is If the temperature change gradient is below the reference value, the amount of change in the skin flow gas temperature Ts is 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 a blowout.

When determining that there is a possibility of an atrium, the computer CMR generates air volume reduction instruction data to prevent an atrium and sends this to the blower BRA via the input/output interface SPC (29), and displays the display on the CRT display Dis. , the current measurement data, judgment data, air volume data of the blower device, and atrium will be updated to indicate caution (3)
0).

If no blow-through is predicted, a signal to maintain the current status at that time is given to the blower BRA (31), and the display on the CRT display 015 is changed to indicate the current measurement data, judgment data, airflow amount data of the blower, and that there is no blow-through. is displayed (32).

〔Effect of the invention〕

According to the first invention, the blowhole is predicted by adding the detection of circumferential changes in the top gas temperature to the detection of changes in the surface level of the charge, resulting in high reliability and improved operational stability. do.

According to the second invention, since the atrium predicts by adding the circumferential variation detection of the skin flow gas temperature to the circumferential variation detection of the furnace top gas temperature, the reliability is high and the operation is improved. Improved stability.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an outline of an apparatus for carrying out the invention of the present application. Figures 2a and 2b show the first example of the first embodiment of the present application.
3 is a flowchart showing the processing operation of the computer CMR shown in the figure. FIGS. 3a and 3b are flowcharts showing the processing operations of the computer CMR in the second embodiment of the present application. Figure 3b■

Claims (2)

[Claims] (1) Detect whether the difference between the upper surface levels at multiple points in the circumferential direction of the blast furnace contents is greater than or equal to a reference value, and also detect whether the rate of descent at each position of the upper surface level is greater than or equal to the reference value. , detects the amount of change and temperature change gradient in the top gas temperature of multiple riser pipes at the top of the blast furnace within a predetermined time, and detects whether the difference in the top surface level at multiple points in the furnace circumferential direction is above the reference value and the top surface level, respectively. At least one of the descending speeds of the plurality of riser tubes is equal to or higher than the reference value, at least one of the top gas temperature change gradients of the plurality of riser pipes is equal to or higher than the reference value, and at least one of the others is equal to or lower than the reference value, and A blow-through prevention method in blast furnace operation that reduces the amount of air blown into the blast furnace when at least one of the furnace top gas temperatures shows a temperature drop above a standard value. (2) Detect the amount of change and temperature change gradient of the top gas temperature in multiple riser pipes at the top of the blast furnace furnace at multiple points in the circumferential direction of the blast furnace directly below the surface of the charge at the top of the blast furnace shaft. Detecting each of the internal gas temperatures, at least one of the furnace top gas temperature change gradients of the plurality of riser pipes is above the reference value, at least one of the others is below the reference value, and at least one of the furnace top gas temperature change gradients of the plurality of riser pipes is One of the gas temperatures shows a temperature drop above the standard value, and the temperature change within a predetermined period of time in the furnace gas temperature at any of multiple points in the circumferential direction of the blast furnace directly below the surface of the charge at the top of the blast furnace shaft is the standard. A method for preventing blow-through in blast furnace operation, which reduces the amount of air blown into the blast furnace when at least one of the plurality of points is equal to or higher than a reference value within a value range.