JP2724364B2 - Blast furnace operation method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of operating a blast furnace, and more particularly, to a method of operating a blast furnace, in which, when an abnormal condition occurs in the furnace condition during operation, the amount of air blown is reduced in response to the abnormal condition. The present invention relates to a method for operating a blast furnace, which smoothly and automatically performs a return action for restoring the operating conditions to the original operating conditions when an action such as an increase in the coke ratio is performed.

2. Description of the Related Art Conventionally, as one method of controlling blast furnace heat by a computer, a so-called Go
A blast furnace management system called -Stop system has been proposed and implemented. This system detects abnormalities in the blast furnace,
In terms of presenting the actions necessary for the recovery, a certain effect can be achieved. However, when the accuracy of furnace heat prediction is low and abnormal situations continue, necessary actions cannot be presented continuously, and the range of use is narrow.

For this reason, artificial intelligence has recently been used to incorporate the know-how of blast furnace operators into this system and to improve the accuracy of predicting the furnace heat required for furnace operation. As disclosed in JP-A-62-270708 and JP-A-62-270712, furnace heat control and furnace condition detection systems using a computer have been proposed. The system disclosed in the former publication determines the furnace heat level based on human judgment rules such as hot metal temperature, tuyere and slag observation, and at the same time, estimates the furnace heat transition based on information from various sensors, and determines the furnace heat level and furnace temperature. The action of furnace heat control is issued based on the heat transition. The system disclosed in the latter publication is similar, but is characterized in that a diagnosis such as slippage or blow-through can be made.

However, these systems all detect an abnormal situation at the present time and aim to avoid the abnormal situation, but when necessary processing is taken to avoid the abnormal situation, the state is restored to the original normal operation. Despite the necessity, no blast furnace operation method including this has been proposed so far.

That is, it is necessary to immediately treat and avoid abnormal situations in the blast furnace operation, and if left untreated, a long-term inconsistency in the furnace conditions such as furnace cooling will occur. Also, avoidance from an abnormal situation can be determined to some extent based on various data and experiences at the time of abnormal furnace conditions in the past, and based on these past data and experiences, conventionally, skilled blast furnace operators have recently It is performed by computer processing using artificial intelligence. On the other hand, if an abnormal situation avoidance process is performed, a return operation to return to a normal state is required. The return operation is originally performed gradually after the furnace condition is stabilized, and has a margin in time as compared with the operation at the time of abnormality which requires immediate treatment. For this reason, the return operation was not much respected as compared with the operation for abnormal avoidance. However, if the recovery is delayed, the situation of low tapping will be continued compared to the normal time, and the economic loss will be enormous, leaving a major problem.

Problems to be Solved by the Invention The present invention aims to solve these problems, and specifically, in a conventional blast furnace operation management system, after taking operation conditions corresponding to abnormalities in the furnace, It is an object of the present invention to solve the problem that it is impossible to cope with a return operation for restoring the original operating conditions after waiting for stability, and that research and development for solving such a problem have not been performed.

Means for Solving the Problems and Their Actions That is, the method of the present invention performs a return operation to return the operating conditions to the original operating conditions when operating conditions corresponding to an abnormal situation in the furnace during blast furnace operation. In doing so, set the coke ratio-change pitch based on the furnace heat state at each unloading level, the stability of the furnace condition, and the elapsed time from the most recent unloading return action at the coke ratio at which the coke ratio is restored to the original operating conditions. Then, it is characterized in that whether or not the return action for each pitch is possible is determined based on the furnace heat state and the stability of the furnace condition, and then the return action is performed to restore the original operating conditions.

Further, according to the method of the present invention, when operating conditions corresponding to abnormalities in the furnace are taken during the operation of the blast furnace, the operating conditions are restored to the original operating conditions upon returning the operating conditions to the original operating conditions. Furnace heat state at each change level of air flow to be
Based on the stability of the furnace condition, the latest wind pressure change, and the tapping balance, the air volume change pitch is set, and the feasibility of the return action is determined for each pitch based on the furnace heat state and the stability of the furnace condition, and then the return action is performed. To restore the original operating conditions.

Further, during the blast furnace operation, when operating conditions corresponding to abnormalities in the furnace are taken during the operation of the blast furnace, when returning the operating conditions to the original operating conditions, in performing the return operation, each of the coke ratios While setting the coke ratio change pitch to restore the original operating conditions based on the furnace heat state at the unloading level, the stability of the furnace condition, and the elapsed time since the last unloading action, Furnace heat state,
Based on the stability of the furnace condition, the latest wind pressure change, and the tapping balance, the air volume change pitch to restore the original operating conditions is set, and the shaft pressure, furnace gas composition, hot metal temperature, and heat balance at the bottom of the furnace are set. In addition, the heat of the furnace and the stability of the furnace condition are determined, and the change of the unloading level and the wind increasing condition are independently selected from the set ranges, and the blast furnace operation is restored.

Therefore, the configuration as these means and the operation thereof will be described in more detail as follows.

First, the present inventors investigated and studied the conditions for properly determining the return action of the system when an action was taken for an abnormal situation in the blast furnace operation, and obtained the conditions as follows. Met.

(1) In response to an abnormal situation in the furnace, for example, when an action such as reducing the load of the coke ratio or reducing the wind is taken, it is determined whether or not it is possible to increase the load or increase the wind as a subsequent return action. (2) The action of returning the coke ratio (CR) and the air volume (BV) is determined by the target value according to the unloading amount (coke ratio) and the amount of wind reduction. (3) taking into account the furnace heat state, the unloading state, the stability of the situation, the tapping balance, the most recent return action and the elapsed time since that time, ) Each return action should be controlled independently of the return of the coke ratio and the return of the air volume, for example, so as not to be complicated.
The coke ratio and the air volume were returned because the typical actions taken in the event of an abnormal blast furnace were reduced load,
This is because these two actions have the greatest effect on the inside of the blast furnace. Therefore, in the present invention, actions other than these actions, for example, blast temperature,
The change of the ventilation humidity etc. is considered as a secondary matter.

Therefore, the return of the coke ratio and the return of the air volume are individually and independently determined and performed as a return action so as to satisfy the conditions (1), (2) and (3) as follows. .

That is, when returning the coke ratio, the furnace heat state, the stability of the furnace condition, and the time elapsed since the most recent increase in the coke ratio depend on how much the load has been reduced (increased coke ratio). The coke ratio return width is determined in consideration of the elapsed time from the most recent coke ratio reduction. If the return of the coke ratio is delayed, a separate return action is determined.

On the other hand, when returning the air flow, the furnace heat state, the stability of the furnace condition, the degree of the latest wind pressure increase, The amount of wind increase in the return operation is determined in consideration of the elimination of the wind reduction factors such as the pig balance, and the return operation is performed in accordance with the amount of increase in wind.

Further, when performing the return operation in this manner, it is necessary to perform the operation after confirming the stability of the operation. Therefore, it is preferable to perform each return operation after a certain period of time.

Next, the first method of the present invention configured as described above is described.
This will be described with reference to the drawings.

First, FIG. 1 is a flow sheet when a blast furnace is operated by the method of the present invention, where Y indicates “Yes” and N indicates “No”. As shown in FIG. 1, the furnace condition was stabilized by reducing the load (increase the coke ratio) or reducing the wind as an appropriate action for the abnormal furnace condition. After the reactor condition stabilization, whether or not the return operation is possible is determined based on the input operation data and determination conditions.When it is determined that the return operation is possible, based on the determination result, each of the previous abnormal situations is determined. In response to the action, an instruction is given to return the unloading level (return the coke ratio) or return the air volume. Whether the return operation is possible or not is determined based on the determination of the furnace heat state and the stability of the furnace condition, as shown in FIG.
If the answer is Yes, that is, if Yes, the return operation is determined, including the items shown in the diamond-shaped frames for each of the action items of the air volume and the coke ratio, and the return amount to be taken in the return operation is set. When the result is NO, that is, when the result is NO, the current operation is continued, and the determination as to whether or not the operation is possible is repeated. In addition, the return amount to be taken in the return operation is divided as described below, and the above determinations are sequentially repeated for the respective return amounts according to the flow shown in FIG. 1 to gradually restore the normal operation. .

So, about the return operation performed as described above,
The following is a more detailed description, sequentially and more specifically, from the return of the reduced load (coke ratio) level.

First, the unloading amount as the return amount is divided into a plurality of parts, and the return action is set for each of the reduced amounts, that is, a determination condition of “Yes” or “No” is set. This determination condition is the first
As shown in the figure, the blast furnace condition used to determine whether or not a return operation is possible is shown.For example, in addition to items such as the furnace heat state and the stability of the furnace condition, the most recent Consider the elapsed time from the loading action to the time of determination. In other words, when a return action is taken for each of the reduced quantities of the load, a determination is made as to whether or not the next return action is possible after waiting for a situation in which the effect of the latest action on the reactor condition has stabilized. In this case, an action instruction amount corresponding to each of the divided unloading amounts is set, and the operation is gradually restored in accordance with the instruction amount. Is preferably set within a range not exceeding. Also, as an item indicating the blast furnace condition, the furnace heat state is typically a tapping temperature, and the stability of the furnace condition is typically represented by a wind pressure fluctuation, CO / CO ₂ fluctuation and slip frequency. Based on these, for example, ranks 1, 2, 3,
As shown in 4 and 5, the items are ranked and associated with the unloading level.

In Table 1, A>B> C (kg / tp)
, And Y ₁ ... Y ₄ are set within a range that does not exceed the unloading level of A, B, C..., And are indicated by (−kg / tp), and X _1.
X ₄ is a time each decompression action in consideration of the influence time which gives the furnace status (e.g. 6 hours, as 10 hours).

Also, as shown in Table 1, the furnace heat can be usually evaluated by (hot metal temperature-target temperature) at the time of determination, and the furnace heat can be predicted by using the change in the heat balance at the bottom of the furnace. It can also be used.

Further, the hot metal temperature used for the determination of the furnace heat and the furnace heat prediction based on the heat balance can be obtained as follows.

Regarding the hot metal temperature, (1) at the start of tapping (1-1) The hot metal temperature representing the current tapping of the previous tapping is defined as the representative hotplate temperature of the current tapping.

(1-2) If the last or second-last hot metal tapping is started after the current tapping is started, then the current representative hot metal temperature at the time of tapping is compared with the previous or previous or previous representative hot metal temperature, and the higher one is the current hot metal temperature. The representative hot metal temperature is used.

(2) At the time of measuring hot metal temperature (2-1) First tapping (whether or not the tapping port has been used in the past fixed time (for example, 24 hours)) is determined.

(I) If it is the first tapping, the representative hot metal temperature is kept as it is.

(II) If it is not the first tapping, perform the following processing.

(2-2) It is determined whether a certain time (for example, 90 minutes) has passed since the start of tapping.

(I) The measured value over a certain time is defined as a representative hot metal temperature.

(II) Only when the measured value within a certain time is equal to or higher than the representative hot metal temperature at that time, the measured value is regarded as the representative hot metal temperature.

(3) Judgment (3-1) When tapping laps (tapping from two tap holes), the higher of the representative hot metal temperatures of each tapping is set as the hot metal temperature for evaluation.

(3-2) When tap hole deviation (when two or more tap holes are used) (3-2-1) [Representative hot metal temperature-previous representative hot metal temperature]> Constant value (15 ° C) (3-2-3) [furnace heat index (current)-furnace heat index (previous)] <constant value (15 ° C) If the above three conditions are satisfied, it is determined that there is a deviation, and only when there is a deviation, it is used for evaluation. Hot metal temperature = 0.5 x (present representative temperature + previous representative temperature) (3-3) Others Hot metal temperature for evaluation = representative hot metal temperature at that time By using the data defining hot metal temperature as described above, the conventional However, it is possible to convert the hot metal temperature measurement result including various disturbances into an evaluation hot metal temperature for judging the state of the furnace heat of the blast furnace. (Constant period) processing can be performed.

About furnace heat prediction Furnace heat prediction is obtained from changes in the heat balance at the bottom of the furnace, and is performed as follows.

(1) Furnace heat prediction (ΔTQ rank) (1-1) The definition of TQ (jo) is shown as follows.

TQ: Heat balance at the bottom of furnace based on 900 ° C.

TQ = Q1 + Q2-(Q3 + Q4 + Q5) (10 ³ kcal / tp) Q1: Sensible heat of blast (at 900 ° C) Q2: Heat of combustion of coke at the tuyere tip (based on CO) Q3: Heat of decomposition of blast moisture Q4: Sorurosu reaction Q5: staves heat extraction (furnace bottom) Q1 = BV '× (BT -900) × 0.335 ( specific heat ^{Kcal / Nm 3 -air) × 10} -3 + BV' × Moist × 10 -3 × (BT-900) × 22.4 / 18 × 0.449 (Specific heat of H ₂ O (g) × 10 ^-3 Q2 = BV ′ × (0.21 + EO ₂ (O ₂ enrichment rate)) × 12 / 11.2 + BV ′ × Moist × 10 ^-3 × 12 / 18) × 2450 (combustion heat of Kcal / kg-C) × 10 ^-3 Q3 = BV '× Moist × 10 ^-3 × 3185 (heat of decomposition Kcal / kg H ₂ O) × 10 ^-3 Q4 = Csol × 3230 (Sorurosu reaction heat Kcal / kg-c) Q5 = ΔQ ( stave heat removal ^{10 3 Kcal / H) × 10} 3/60 / Pig ( Zozuku speed t / Min) heat extraction rate of the C ₁ + furnace bottom.

BV '; Unit air intensity (N m ³ / t-p (including EO ₂ ) BT; Air temperature (° C) Moist; Air humidity (g / N m ³ ) Csol: Sollos C (kg / t-p) ( 2) The definition of ΔTQ (jo) is shown as follows.

However, jo, jo-a ...: furnace heat judgment timing By dividing the magnitude of ΔTQ obtained in this way, it is used as an index for judging furnace heat. Preferably, the accuracy can be further improved by further dividing ΔTQ according to the variation and performing furnace heat prediction.
This variation is performed by obtaining RΔTQ.

(3) The definition of RΔTQ (jo) is shown as follows.

In addition, the stability of the reactor condition is determined by the wind pressure fluctuation CO / CO ₂
The magnitude is evaluated for each item such as fluctuation, slip frequency, etc., and the stability is detected from the combination to rank the items. This is performed as follows.

For example, (I) Wind pressure fluctuation large, medium, small (II) CO / CO ₂ fluctuation large, medium, small (III) Slip frequency Classified as large, medium, small, and based on the combination of large, medium, and small The degree of stability is determined in advance by ranking.

In addition, the elapsed time of the most recently taken action is to consider whether or not the changed part of the coke ratio changed by the most recently taken action remains in the furnace. Sometimes return operation starts. That is, in the case of coke, as long as the coke remains in the furnace, the effect of the charged coke is reflected in the furnace. Therefore, it is not possible to classify only the judgment based on the furnace heat and the furnace condition based on the latest unloading action taken, and the elapsed time is returned to the operation criterion.

 Next, the return of the air volume will be specifically described.

In this case as well, similar to the above-described return of the unloading level (coke ratio), the level of wind reduction is divided into a plurality of levels, and the condition for determining whether or not the return action is possible is set for each section. The furnace heat state and the stability of the furnace condition are determined in the same manner as when the unloading level is returned, and the possibility of return is determined based on the latest wind pressure increase and Pig balance, and the return is performed for each of the above categories of reduced wind. The air volume is determined stepwise, for example, as shown in Table 2.

In the case of a change in the air flow rate, the effect is reflected in the furnace condition in a short time, so the latest wind pressure rise and Pig balance
Judgment can be made based on the most recent situation of 30 minutes to 1 hour. Note that the action amount (wind increase amount) is set for each wind reduction level, and the restoration operation is smoothly implemented by providing a restriction on the wind increase pitch. In addition, the start of the recovery from the abnormality is performed including the influence of the wind reduction in the latest situation on the furnace, and is performed after an elapsed time of 30 minutes to 1 hour as in the case of the wind pressure rise and the Pig balance.

Example Due to an abnormal increase in wind pressure during operation,
Nm ³ / min to up to 6000Nm ³ / minute was 1000Nm ³ / minute, down wind.

Then, in order to increase the amount of the reduced wind 1000 Nm ³ / min and return the blowing condition to the original state, the reduced wind bell 1000 Nm ³ / min.
The fraction was divided into 100 Nm ³ / min, and the wind was increased by the method of the present invention, and a return operation was performed as shown in FIG.

In other words, FIG. 1 is a graph showing the change over time in the amount of air blown when the operation of returning the amount of air blow is performed according to the method of the present invention. The operations are divided into (a), (b), and (c).
And each section of (d).

(A) Section: In this section, 1000Nm ³
/Min./min./min. That is, after the continuation of the wind reduction operation for 5 minutes, it is determined whether or not the return operation is possible.
That is, since it was determined to be “Yes”, the return operation was started as follows.

(B) Section: Return operation was started from this section, and determination was first made at an air volume level R (= current air volume / target air volume) <0.9.

The return operation was performed under the condition that the furnace condition stability rank was 3 or less, the furnace heat level was 3, the latest wind pressure rise was <0.015, and the tapping balance was ≧ -300 t. In this case, the unit of wind increase is
100Nm ³ / minute, 15-minute intervals, increasing wind pitch was 300Nm ^3/60 minutes.

(C) Section: a section with an airflow level R <0.95, and since this section was reached, judgment was made at a level of R <0.95.

The furnace condition stability was rank 2 or less, the furnace heat level was 4, the latest wind pressure rise was <0.010, and the tapping balance was returned under the return condition of ≧ -300t. In this case, the wind increase unit is 100N
m ³ / min, 15 minutes, increasing wind pitch was 200 Nm ^3/60 min.

(D) Section: This section was determined at an air volume level R ≧ 0.95.

The furnace condition stability was ranked 1 or lower, the furnace heat level was 5, the latest wind pressure rise was <0.010, and the tapping balance was ≧ -300 t. In this case, the unit of wind increase is
100 nm ³ / min, 25 minute intervals, the pitch was 200 Nm ^3/60 min.

<Effects of the Invention> As described in detail above, the method of the present invention, when operating conditions corresponding to the abnormal situation that occurs during the operation of the blast furnace,
This is a method of performing a return operation to restore the operating conditions to the original state, in which the unloading level of the coke ratio is determined by the furnace heat at each level, the stability of the furnace condition, and the elapsed time from the last unloading action. On the other hand, the wind reduction level is set based on the furnace heat at each level, the stability of the furnace condition, the latest wind pressure rise, and the tapping balance. Recovery operation is performed after judging the furnace heat and the stability of the furnace condition.

Accordingly, the method of the present invention accurately determines the return action such as the wind reduction in the blast furnace operation, the air volume after the unloading, the coke ratio, and the like, so that the operation management system of the blast furnace can be applied to the return action. Was.

[Brief description of the drawings]

FIG. 1 is a flow sheet of an operation management system used in carrying out the method of the present invention, and FIG. 2 is a graph showing the relationship between time and air flow according to an example of the embodiment of the method of the present invention.

Claims (3)

(57) [Claims] When operating conditions corresponding to an abnormal situation in the furnace are taken during operation of the blast furnace, the operating conditions are restored to the original operating conditions, and the original operating conditions are restored. The coke ratio-change pitch is set based on the furnace heat state at each unloading level of the coke ratio, the stability of the furnace condition, and the elapsed time from the most recent unloading return action, and the furnace determines whether the return action can be performed for each pitch. A method for operating a blast furnace, characterized in that a return action is performed to restore the original operating conditions after a judgment is made based on the thermal state and the stability of the furnace condition. 2. When operating conditions corresponding to an abnormality in the furnace are taken during the operation of the blast furnace, when the operating conditions are returned to the original operating conditions, a return operation to restore the original operating conditions is performed. Based on the furnace heat state at each change level of the air flow, the stability of the furnace condition, the latest wind pressure change and the tapping balance, a pitch for changing the air volume is set. A method for operating a blast furnace, comprising: performing a return action after a determination based on stability to restore the original operating conditions. 3. During the operation of the blast furnace, when operating conditions corresponding to abnormalities in the furnace are taken, when the operating conditions are returned to the original operating conditions, when the return operation is performed, each reduction in the coke ratio is performed. While setting the coke ratio change pitch to restore the original operating conditions based on the furnace heat state at the level, the stability of the furnace condition, and the elapsed time from the last unloading action,
Based on the furnace heat state at each change level of the blown air volume, the stability of the furnace condition, the latest wind pressure change and the tapping balance, set the air volume change pitch to restore the original operating conditions, shaft pressure, furnace gas composition, Judging the furnace heat and the stability of the furnace condition based on the hot metal temperature and the heat balance in the lower part of the furnace, restoring the blast furnace operation by independently selecting the unloading level change and the wind increase condition within the set range A method of operating a blast furnace, which comprises operating the furnace.