JPH04350108A - Method for controlling blast furnace - Google Patents

Abstract

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

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention controls the radial gas flow distribution in the blast furnace by controlling the charge distribution in the blast furnace and confirming the effect by directly measuring the gas flow velocity distribution in the radial direction of the blast furnace. This invention relates to a method for operating the inside of a blast furnace in a stable state by performing this process more quickly and accurately, preventing the generation of an inactive zone.

0002

BACKGROUND OF THE INVENTION Controlling the gas flow velocity distribution in the radial direction of a blast furnace (hereinafter referred to as gas flow distribution) is recognized as important in ensuring efficient and stable operation of the blast furnace. If the gas flow velocity forms a greatly uneven distribution in the radial direction of the blast furnace, an excessive gas flow rate will cause a blow-through phenomenon, and an insufficient gas flow rate will cause a lack of heat, both of which will lead to major operational troubles. Therefore, it is important for blast furnace operation to form a gas flow distribution that is optimal for the conditions in which each blast furnace is placed, without causing the gas flow velocity to locally become too high or too low.

Conventionally, the only means of controlling gas flow distribution has been the radial layer thickness distribution or particle size distribution (hereinafter referred to as charge distribution) of ore and coke charged from the top of the furnace.
The technology to control this has been developed. There are two methods, such as a method using a bell-shaped charging device and controlling it using a movable armor, and a method using a PW charging device to control the position and rotation speed of a rotating chute. Various charging patterns can be set according to the operating conditions of the blast furnace, and it has become possible to control the burden distribution to a state close to the pattern envisioned by the operator.

On the other hand, several methods have been tried to confirm the effect of the charged distribution. The first method is to measure the profile of the charging surface at a certain point in time using a multi-point sounding device, laser profile meter, or ultrasonic profile meter installed at the top of the furnace. The layer thickness distribution (hereinafter referred to as LO/LC distribution) of the ore layer and coke layer immediately before and after charging is estimated from the measured data, but this method involves the following problems.

[0005] First, since the charging surface profile changes over time until the next charging, it is necessary to correct the charging surface profile depending on how many minutes have passed since the data at the time of measurement was charged. occurs. In other words, it is necessary to accurately grasp changes over time, which is likely to cause errors. Furthermore, since the lower charge has a descending speed distribution, it is necessary to make corrections that take into account time-series changes in the descending speed distribution. Furthermore, when an ore layer is charged on top of a coke layer, the coke layer is broken down and tends to accumulate in the center. For this reason, it becomes necessary to correct the layer thickness distribution of the ore layer and the coke layer.

[0006] In order to make these corrections, detailed elucidation of the above-mentioned phenomena must be studied, and accurate quantification is also required, but at present the elucidation has not progressed as expected. The second method to confirm the effect of charge distribution is to estimate the strength of the gas flow by measuring the radial gas temperature distribution with a thermometer installed at the top of the furnace. At the top of a blast furnace, the charging surface slopes like a mortar from the center to the periphery, and this slope causes the gas flow to rapidly change from the periphery to the center. Generally, high temperatures are measured in areas where the gas flow rate is high, but near the top of the furnace the gas flow is affected by this slope, so the measured temperature distribution reflects only the charge distribution. Estimating the distribution is difficult.

A third means of confirming the effect of charge distribution is to estimate it from the data of the radial gas concentration distribution sampled by an upper-shaft sonde installed in the charge at the top of the blast furnace. It's a method. Since the sonde is inside the charge, this method is currently the most reliable and widely used method. In this method, CO and CO2
Gas concentration ratio or gas utilization rate ηCO=CO 2/
The gas flow velocity distribution is estimated using (CO+CO 2) as an index.

This method is based on the phenomenon that where the gas flow rate is high, the temperature is high and the CO/CO 2 concentration ratio is also high. It is true that this method is excellent as an index representing the gas flow distribution macroscopically, but for example, η
In addition to phenomena originating from the burden distribution, CO is also affected by reduction, and information other than the gas flow rate is also superimposed, such as being affected by the temperature in the lower part of the furnace. It is not a strict method of confirmation. Furthermore, the index ηCO itself is a relative concentration ratio of gases, and does not represent the absolute amount of gases. It is an effective indicator only when the quantitative value of gas flow rate is known. Considering the above, the conventional method is insufficient as a method to confirm the effect of manipulating the burden distribution, and therefore it can be said that the above method is incomplete in quantitatively controlling the entire blast furnace by controlling the burden distribution. I don't get it.

[0009]

[Problems to be Solved by the Invention] In order to solve the above-mentioned problems, the present invention aims to accurately determine the effect of charge distribution by quickly detecting the gas flow distribution in the blast furnace. The purpose is to quickly control the gas flow distribution in the blast furnace to a set state through rapid control of the charge distribution, thereby obtaining the optimal gas flow velocity distribution for the operating conditions.

0010

[Means for Solving the Problems] The present invention provides a shaft sonde installed in the blast furnace shaft, in which a gas flow meter and a pressure measurement hole are installed in addition to the usual gas sampling hole and temperature measurement part, so that the gas concentration distribution and temperature can be measured. In addition to distribution measurements, gas flow rate measurements are also performed at the same time. As a result, the distribution of the gas amount in the radial direction is measured taking into account the material balance, and the radial charge distribution is controlled by estimating the ventilation resistance in the radial direction that satisfies the balance. .

[0011] That is, the gist of the present invention is to
A gas flow meter that can measure in the radial direction, a pressure detection end, a gas concentration meter, and a thermometer are attached to the sonde installed at the top of the shaft, and based on the data obtained from these instruments and the detection end, the gas flow velocity in the radial direction can be calculated. Find the distribution,
This blast furnace control method is characterized by comparing a target gas flow velocity distribution set in advance and controlling the charge distribution according to the difference between the two.

0012

[Function] The present invention will be explained in detail below along with its function. First, a measuring device is installed in the blast furnace under the following conditions. That is, in addition to the usual gas sampling hole and temperature measurement part, a gas flow meter and pressure measurement hole are installed in the shaft sonde installed in the shaft part of the blast furnace. This probe may be installed at multiple detection holes in the radial direction for simultaneous measurement, or may be installed only at the tip of the probe and measured while moving. In addition, the upper and lower positions of this probe should be as close to the final value of the gas concentration as possible in order to perform gas sampling at the same time, but if it is too high, the gas flow rate will be affected by the slope of the upper part. 2 to 5 meters below is appropriate. Hot wire type, turbine type, and heat flow velocity measurement types can all be installed as gas flow meters.

FIG. 2 shows an example of the structure of the tip of the detection end of the probe. A through hole 20 through which gas flows is installed at the tip. This through hole has almost no resistance to gas flow, and is provided with reinforcing grids 21 and blades 22 at the top and bottom of the through hole to protect the detection end from the upper load and to prevent dust. It has a structure. In this example, a hot wire type gas flow meter 23 is provided in the center of the through hole to measure the gas flow rate, and at the same time, the gas temperature is measured by a thermocouple 24. The gas concentration is sucked from the side 25 of the through hole, and the pressure is detected at the same time.

Based on the above-mentioned apparatus premise, the gist of the present invention will be explained below with reference to the drawings. FIG. 1 is an explanatory diagram showing an overview of the method of the present invention. 1 is a gas flow rate measurement part, 2 is a pressure measurement hole, 3 is a gas sampling hole, and 4 is a gas thermometer, and these signals are sent to the outside via a data processing device. Sent. 5 is a shaft upper sonde, and 6 is a blast furnace. 7 is a charging device;
8 is an ore layer charged by the charging device, 9 is a charged coke layer, and 10 is an arithmetic device that calculates the current ventilation resistance distribution (Ki distribution) from the measured gas flow rate 1 and pressure 2. , 2, and 4. 11 is a display mechanism for outputting the ventilation resistance distribution and gas flow velocity distribution.

12 is a mass velocity calculation mechanism for each gas composition; 1;
Connected with 2, 3, and 4. 13 indicates a display mechanism for mass velocity according to gas composition. Reference numeral 14 denotes an arithmetic mechanism that calculates the current layer thickness distribution from the ventilation resistance distribution or the mass velocity distribution by gas composition, and can be switched by switches 17 and 18 depending on the purpose. Reference numeral 15 denotes a charge distribution calculation mechanism, which predicts the charge distribution to be set next by taking into account the difference between the current gas flow pattern and the target gas flow pattern; 16.

As described above, this system has the radial ventilation status detection functions 10 and 11, the reduction status detection function 12,
It has 13. Next, the calculation mechanism 10 for estimating the ventilation resistance distribution from the gas flow velocity distribution in the present invention will be explained. First, the local gas mass velocity G (obs) is determined from the measured Ui distribution using Equation 1. Next, the total gas amount TG (obs) is determined using Equation 2. TG (obs) is the gas amount TG (c
A correction is applied to Ui until it matches al). The gas density ρ(gi) is determined from the measured temperature and gas pressure. Next, using Equation 3 from the measured gas flow velocity Ui at each point, the distribution of ventilation resistance Ki distributed by Ui under constant pressure loss is determined.

[Math 1]

[Math 2]

[Math 3]

[Math 4]

[0017] However, Ui; measurement gas flow velocity distribution
(m/s) ρ(gi); Gas density (
kg/cubic meter) G (obs); Measured gas mass velocity (kg/m2・sec) TG (obs); Total gas volume (kg/s
)r ; radial position
(m) ΔP/L ; Pressure loss
(kg/cubic meter) Ki ; Airflow resistance coefficient Lo/Lc
;Layer thickness ratio

Layer thickness ratio Lo/L of ore and coke at the top of the furnace
The relationship between c and Ki is determined in advance by Equation 4, and this Lo/Lc distribution is determined by the arithmetic mechanism 14 that calculates the layer thickness distribution. Next, the charge distribution calculation mechanism 15 predicts the charge distribution to be set next by taking into account the difference between the current gas flow pattern and the target gas flow pattern, and the charge distribution control device 16 controls the prediction. be done.

Next, the return status detection function will be explained. The gas concentration is determined by the gas sampling hole 3.
, H 2 , H 2 O, and N 2 , or even if there are less than 5 components, the 5 components are calculated based on the measurement results. Next, these are combined with the gas flow velocity distribution and calculated as the mass velocity of a single gas by the mass velocity calculation mechanism 12 for each gas composition. For example i
Since the concentration F(COi) of CO gas at a point is detected as a fraction or %, this is converted into a mass velocity using Equation 5.

[Math 5]

[Math 6]

[Math 7]

[0020] where G(COi); CO gas mass velocity
(kg/m2・sec) G(CO 2i); CO 2 gas mass velocity
(kg/m2・sec) T(CO); Total amount of CO gas
(kg/s) F(COi); Concentration of measured CO gas

00
21] F(COi) is simply a gas concentration and is an intensive variable, but G(COi) is an indicator variable that includes information up to the gas amount and can be expressed as the absolute amount of reducing gas, so its relationship with the overall mass balance is It becomes a variable that can be evaluated. Further, the total CO amount T(CO) is calculated as shown in Equation 6. The total amount of CO in the calculation T(COobs) is calculated from the gas component at the top of the furnace, so T(CO) is T(COobs)
Ui is modified until it matches. For example, the CO mass velocity G (COi) and CO 2 mass velocity G (CO 2i) determined in this way represent the reduction ability of the i-th point in the radial direction with respect to CO reduction, which is dramatically greater than the above-mentioned ηCO. The information has been improved.

The calculation for controlling the charge distribution depending on the reduction situation is performed as follows. Lo/Lc from the perspective of reduction
The relationship between G(COi)/G(CO 2i) has already been found from equation 7, and the current
By knowing the information of (CO2i), the layer thickness distribution calculation mechanism 14 can estimate (Lo/L)i. The charge distribution is changed so that the current distribution of G(COi)/G(CO2i) at each point becomes the preset target value, and a new distribution is calculated by the charge distribution calculation mechanism 15 according to Equation 7. built into it.

[0023]

[Examples] Examples of the present invention are shown below. FIG. 3 shows the charge distribution, Lo/Lc distribution, and measured gas flow velocity distribution before correction in an actual blast furnace. This charge distribution is estimated by the charge distribution calculation mechanism 15. This gas flow velocity distribution has a deviation from the target gas flow velocity distribution.

Here, it is desired to obtain a target gas flow velocity distribution by changing the charge distribution. Figure 4 shows the corrected charge distribution, Lo, obtained by the charge distribution calculation mechanism and charge distribution control mechanism in order to obtain the target gas flow velocity distribution.
/Lc distribution and the measured gas flow velocity distribution are shown. This distribution matches the target gas flow velocity distribution. In other words, by directly measuring the gas flow velocity distribution, it has become possible to easily form a distribution close to the target.

[0025]

[Effects of the Invention] According to this method, it is possible to quickly control the charge distribution by directly measuring the gas flow velocity distribution, prevent delays in action, and effectively prevent ventilation abnormalities. The blast furnace can be operated smoothly by reducing this amount. Further, according to such a gas flow velocity distribution control method, there is no need to take excessive actions or trial-and-error actions as in the conventional method, and it becomes possible to quickly realize an appropriate distribution.

[Brief explanation of the drawing]

[Figure 1] A configuration diagram showing the entirety of the present invention

[Fig. 2] A diagram showing the structure of the detection end tip of the probe used in the present invention.

[Figure 3] Diagram showing the charge distribution, Lo/Lc distribution, measured gas flow velocity distribution, and target gas flow velocity distribution before correction

[Figure 4] Diagram showing the corrected charge distribution, Lo/Lc distribution, measured gas flow velocity distribution, and target gas flow velocity distribution

Claims (1)

[Claims] [Claim 1] A sonde installed at the top of the shaft includes a gas flow meter that can measure in the radial direction, a pressure detection end,
Attach a gas concentration meter and a thermometer, determine the gas flow velocity distribution in the radial direction based on the data obtained from these instruments and the detection end, compare it with the preset target gas flow velocity distribution, and adjust the difference between the two. A method for controlling a blast furnace, characterized in that the distribution of the burden is controlled.