JP3151803B2 - How to diagnose tuyere damage - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for diagnosing a tuyere breakage which can early detect breakage of a blowing tuyere of a blast furnace, a shaft furnace, a hot blast stove, etc. and can estimate a diameter of the tuyere.

[0002]

2. Description of the Related Art A tuyere of a blast furnace, a shaft furnace, a hot blast stove, etc., for example, a tuyere of a blast furnace is a hot blast stove of 1100-125.
A blowing port provided for uniformly blowing air heated to a high temperature of 0 ° C. into a blast furnace, and which is usually a high-speed cooling method made of copper is mainly used. In this tuyere cooling method, the tuyere is not greatly damaged by hot metal, and even if it occurs, it is only a pinhole. In addition, in the case of tuyere damage, the frequency of erosion by hot metal decreases, and wear at the tip becomes dominant. Therefore, it is necessary to detect damage at the time of a small hole.

[0003] Conventional methods for detecting blast furnace tuyere damage include:
Monitoring by hydrogen (H ₂ ) gas analysis generated by a so-called aqueous reaction (H ₂ O + C → H ₂ + CO) in which the cooling water reacts with coke when water leaks into the furnace, or the cooling water pressure at the tuyere A method of detecting the CO gas mixed in the cooling water by gas analysis has been adopted, but there is a problem in disturbance and operability, and it is not satisfactory in terms of reproducibility and reliability.

As a countermeasure, a Karman vortex flow meter is provided at one of the supply / drain pipes of the cooling water at the tuyere. A method is compared with one of the integrated values before the one at the time of the integration, issues an alarm if the difference exceeds a certain value, and closes the shutoff valve on the water supply side if the difference becomes larger (particularly Kuniaki 51-600
No. 8), a device for detecting leakage of cooling water by using an output difference of a digital flowmeter which outputs a number of pulses proportional to the flow rate of cooling water installed in a supply / drain pipe of cooling water at the tuyere. Two counting circuits to be respectively connected to the output terminals of the counter, a timing control circuit for synchronously and periodically controlling the operation time and the idle time of the counting circuit, and an arithmetic circuit for calculating an output difference of the counting circuit A comparison circuit that compares the output of the arithmetic circuit with a predetermined allowable value, a storage circuit that continuously stores an output signal of the comparison circuit, and output terminals of the comparison circuit and the storage circuit. A device consisting of two alarms connected to each other (Japanese Patent Laid-Open Publication No. 52-2814), an integrating circuit is connected to each of a feed water flow meter and a drain flow meter in all cooling systems, and the total number of times of integration is measured. The operation time and the pause time are controlled synchronously and periodically by the same timing control circuit, and the output of the integrating circuit connected to the feedwater flow meter and the integrating circuit connected to the wastewater flow meter for each cooling system. A flow difference signal having a magnitude corresponding to the difference with the output is electrically detected. On the one hand, the flow difference signal is input to a storage device and stored for a certain period of time, and on the other hand, is input to a comparison operation device to set the set limit. The value is compared with the set alert value, and only when the magnitude of the flow rate difference signal exceeds the limit value and when the value falls below the alert value and continues to exceed the alert value for a certain period of time or longer, the storage device performs the process up to that point. A method of recording a flow difference signal and / or a flow difference signal generated after that time and operating an alarm (Japanese Patent Application Laid-Open No. 53-122475). The difference is calculated, the flow rate difference data is held for a predetermined time, and when the flow rate difference data exceeds a set value, the held data is recorded at a speed higher than a normal recording speed, so that the blast furnace Method for quickly and accurately grasping the state of damage to tuyere
No. 9-65743) has been proposed.

[0005]

SUMMARY OF THE INVENTION The above Japanese Patent Publication No. Sho 51-60
08, JP-A-52-2814, and JP-A-53-2814.
-122475 and JP-A-59-65743.
The method disclosed in Japanese Patent Publication No. JP-A-2005-27209 is to detect the presence or absence of damage to the tuyere by comparing the flow rate difference between the water supply flow rate and the drainage flow rate or the integrated value at a fixed time and the set value. Be sure to shift the zero point (hereinafter referred to as offset value)
Therefore, if a simple comparison of the flow rate difference or a comparison with the sound integrated value alone is made, it is extremely accurate to determine that the damage is a damage such as a minute leak such as a minute pinhole, apart from a large breach. become worse.

In the above prior art, it is indispensable to solve the problem of the offset value peculiar to the sensor, and it suffices if the automatic calibration function is simply provided.
It is very difficult to match the calibration timing of the two flow meters installed on the water supply and drainage side. In addition, since a normal blast furnace uses 20 to 40 tuyeres, it has a function. Even so, a false alarm or the like may occur, causing a problem in use.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned disadvantages of the prior art and to provide a tuyere damage diagnosis method capable of detecting damage such as minute leaks such as minute pinholes with high accuracy and at an early stage. is there.

[0008]

SUMMARY OF THE INVENTION According to the method for diagnosing tuyere damage according to the present invention, when a difference flow rate between a feed water flow rate and a drain flow rate exceeds a predetermined set value, the feed water pressure is changed to determine the difference between the flow rate and the furnace pressure. Find the correlation with the difference flow rate of cooling water when the pressure difference is changed
And create a regression equation to calculate the differential flow rate at the point where the differential pressure becomes zero.
Line with, in the case of damage to the tuyere estimated damage caliber from the slope of the regression equation to determine whether the breakage or the error of the meter from the value tuyere
It is and TURMERIC. Thus, exceeds the set value the difference flow rate is predetermined by obtaining a correlation between a difference flow rate of the cooling water when varying the water pressure was changed pressure difference between the furnace pressure
Create a regression equation and calculate the differential flow rate at the point where the differential pressure becomes zero.
In addition to determining whether the tuyere is damaged or an instrument error from the value, in the case of tuyere damage, by estimating the damaged bore from the slope of the regression equation, the difference flow rate caused by the offset value,
It is possible to determine whether the flow rate is different due to breakage, and to detect breakage such as minute leaks such as minute pinholes with high accuracy and at an early stage, and to easily grasp the damage situation. it can.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The amount of water leakage (Δ
Q) is determined by the pressure difference between the feed water pressure (Pw) and the furnace pressure (Pi) and the opening area (A), and is expressed by the following equation (1). The difference flow rate between the supply water flow rate and the drainage flow rate is expressed by the following equation (2). ΔQ = αA√ [2g (Pw−Pi) γ] (1) Equation ΔQ = Q ₁ −Q ₂ (2) where α: coefficient, A: opening area (cross-sectional area at break), g: gravity acceleration, Pw: feedwater pressure, P
i: Furnace pressure, γ: Specific gravity of water, ΔQ: Water leakage into the furnace (differential flow), Q ₁ : Feed water flow, Q ₂ : Waste water flow.

Accordingly, the difference (differential flow rate) between the flow meter on the water supply side and the flow meter on the drainage side changes depending on the pressure difference between the water supply pressure and the furnace pressure. If one of the pressures is changed, the differential flow should change. In this case, since the pressure in the furnace cannot be controlled from the viewpoint of ensuring operation stability, the water supply pressure side is changed. However, the pattern at the time of this change can be easily understood to be as shown in FIG. 2, and (Pw-Pi) The regression line in the correlation diagram between ΔQ and ΔQ is shown by the following equation (3). In this case, the differential pressure between the feed water pressure and the furnace pressure is changed to ΔP ₁ and ΔP _{2 based} on the differential pressure ΔP _N at the normal operating point. ΔQ = αA√ [2g (Pw−Pi) γ] + β (3)

In FIG. 2, the curve indicated by black circles (A) is the data when actual breakage occurs, and αA, which is a constant determined by the damage state (cross-sectional area), and the offset value β of the flow meter are constant. Therefore, the differential flow rate ΔQ is √ [2g (Pw−Pi) γ]
Is proportional to On the other hand, the curve (a) marked with a cross indicates that the offset value (β ') is dominant from the beginning and the differential pressure between the furnace pressure and the feedwater pressure is obtained even when the differential flow rate (ΔQ) occurs. Does not substantially change at a constant value even when is changed, that is, when viewed from a regression equation, αA√ [2g (Pw-Pi) γ] ≪β, and it is possible to determine whether the device is damaged or not.

According to the present invention, in accordance with the basic principle as described above, data is collected for each condition of the differential pressure between the furnace pressure and the feedwater pressure, and the data is numerically processed to obtain a regression equation. Pressure differential term {αA} [2g (Pw-Pi)
γ]｝ and the offset value (β). First, from the differential pressure term {αA} [2g (Pw−Pi) γ]},
When A is obtained, the opening diameter (D) of the damaged portion is obtained by the following equation, and it can be determined whether the hole is a minute pinhole or a relatively large damage having a diameter of about 1 to 2 mm. D = √ [(4αA) / π] If α = 1, D = √
[(4 / π) A]

Further, the differential flow rate (ΔQ _N ) at the normal operating point is compared with the differential flow rate (ΔQ ₀ ) when the differential pressure becomes zero from the regression equation, for example, ΔQ ₀ / ΔQ _N ≧ 0.90 If so, it is determined that there is an error due to the occurrence of an offset, and a measure for adjusting the zero point of the flow meter is performed. If ΔQ ₀ / ΔQ _N <0.90, it is considered that the tuyere is damaged and a large amount of water enters the furnace. Adjust the water supply pressure and water volume so that they do not enter.

[0014]

【Example】

Embodiment 1 Hereinafter, details of a tuyere damage diagnosis method according to the present invention will be described with reference to FIG. 1 showing an embodiment. FIG. 1 is a schematic explanatory diagram of a blast furnace tuyere cooling system provided with the tuyere damage diagnosis method of the present invention. In FIG. 1, reference numeral 1 denotes a water supply header to which cooling water supplied from a water supply facility (not shown) is supplied.
In the water supply pipe 3 connecting the water supply header 1 and the tuyere 2, an inlet valve 4, a water supply side electromagnetic flowmeter 5, a flow control valve 6, and a water supply pressure gauge 7 are installed in this order from the water supply header 1 side. The cooling water is supplied to the tuyere 2 via the inlet valve 4 of the water supply pipe 3, the water supply side electromagnetic flow meter 5, the flow control valve 6, and the water supply pressure gauge 7. A drain header 8 discharges cooling water to a drain not shown. In the drain pipe 9 connecting the drain header 8 and the tuyere 2, a flow control valve 10, a drain side electromagnetic flow meter 11, a three-way drain valve 12, and an outlet valve 13 are installed in this order from the tuyere 2 side. The cooling water is discharged to the drain header 8 through the flow control valve 10, the drain side electromagnetic flow meter 11, the drain three-way valve 12, and the outlet valve 13.

Numeral 14 denotes a damage diagnosis control unit, which receives the water supply flow rate and the waste water flow rate measured by the water supply side electromagnetic flow meter 5 and the drainage side electromagnetic flow meter 11 and inputs the water supply pressure measured by the water supply pressure gauge 7. Is entered. The furnace pressure measured by the furnace pressure gauge 15 provided near the tuyere 2 is input to the damage diagnosis control unit 14. 16 is a damage diagnosis control unit 14
Is a keyboard for inputting a set value to the. The damage diagnosis control unit 14 determines the difference between the flow rate of the feed water and the flow rate of the waste water (Δ
Q) is calculated by the above equations (1) and (2), and is compared with a set value input in advance from the keyboard 16 to constantly monitor.

When the difference (ΔQ) between the water supply flow rate and the drainage flow rate exceeds a set value, the damage diagnosis control unit 14 issues an alarm and gradually narrows the inlet valve 4 so that the tuyere water supply pressure Pw decreases. Under a condition (Pw> Pi) higher than the furnace pressure Pi input from the internal pressure gauge 15, the differential pressure (ΔP _N ) between the furnace pressure Pi and the tuyere feedwater pressure Pw during normal operation is, for example,
The flow rate is reduced stepwise to 80%, 60%, and 30%, and the difference flow data between the supply water flow rate and the drainage flow rate is calculated for each step. The difference flow rate data to be calculated in this case is not limited to the three patterns described above, and the number n can be increased under the condition of 0% or more. Further, the throttle operation of the inlet valve 4 may be performed manually or remotely, and the operation may be performed under the conditions by monitoring the difference (Pw−Pi) between the tuyere feed pressure Pw and the furnace pressure Pi. is important. For example, Pw
When the condition of −Pi <0 is satisfied, the gas in the furnace may flow back into the tuyere 2, and the contents such as dust may block the drain side, and the flow of the cooling water may be interrupted, resulting in a severe wreck.

The damage diagnosis control unit 14 plots the differential flow rate (ΔQ) for each of the calculated differential flow rate data, and obtains a regression equation. For example, when there is a pinhole having a furnace pressure of 3.2 kg / cm ² , a tuyere water supply pressure of 7.0 kg / cm ² , and a diameter of about 2 mm (assuming α = 1 and β = 0 at this time) ΔQ = ( π / 4) D ² × {[2g (Pw-Pi) γ] × 3600 = 3.14 × 10 ⁻⁶ ×} [2 × 9.8 (7.0-3.2) × 10 ⁴ × 0. 001] × 3600 = 0.31 m ³ / hr theoretically, and 80% of the pressure difference between the furnace pressure Pi and the tuyere feedwater pressure Pw during the normal operation, 60%
%, 30%, the differential pressure (ΔP) and the differential flow rate (Δ
Q) is as shown in Table 1.

[0018]

[Table 1]

In practice, the indication of the difference flow rate (ΔQ) is reduced as described above, but the data may vary due to some errors.
Finds a regression equation for these data as shown in equation (3).

The damage diagnosis control unit 14 calculates αA of the differential pressure term {α {[2g (ΔP) γ]} of the regression equation obtained above.
, The hole diameter (D) of the damaged portion is obtained, and the offset value β of the meter is obtained. As described above, it is determined whether the tuyere 2 is damaged or the meter is caused by an error.
In this case, for example, for a hole diameter of 2 mm, usually 0.3 mm
1 m ³ / hr as the amount of leakage (flow rate) of, when reducing the differential pressure furnace pressure and tuyeres water pressure during normal operation to 30%, 0.17m ³ /hr[√(0.3 )] About 0.55
It can be sufficiently grasped within the accuracy of the electromagnetic flow meters 5 and 11. The damping time constant (T) is set (10 seconds in this case) in the electromagnetic flowmeters 5 and 11, and a time delay occurs until the numerical value is stabilized. (After 50 seconds in this case)
Collect data from Therefore, the sampling timing is as shown in FIG.

Further, in the present invention, as described above, one of the conditions is to change the pressure difference ΔP between the tuyere feed pressure Pw and the furnace pressure Pi. Uses the pressure measured by the pressure gauge 7 at the feed water inlet as a representative point, and does not directly compare the pressure with the pressure inside the furnace, but instead measures the pressure loss from the installation position of the pressure gauge 7 to the tip of the tuyere 2. Subtract Furthermore, since the tip portion of the tuyere 2 has a high flow velocity, the static pressure is reduced by the hydrodynamic pressure, so that the correction including this is necessary. The correction formula is as follows.

_Assuming that the pressure measured by the pressure gauge 7 is P _w1 ,
The pressure of the tip portion of the tuyere _{2, Pw = P w1 -ΔP w1 -V} N 2 / (2g) γ However, [Delta] P _w1 is water from the pressure gauge 7 installed position of the flow rate thereof to the tip of the tuyere 2 With the side pressure loss, the design flow Q
_Let the pressure loss at _{D be} ΔP _wD . The feed water flow at the time of data collection When Q _N, can be calculated by the following equation. ΔP _w1 = ΔP _wD × (Q _N / Q _D ) ² Also, V _N ² / (2 g) γ is the dynamic water pressure at the tip of the tuyere 2, and V _N is the tip flow rate when the feedwater flow rate is Q _N. Represent. The flow rate at the time of design flow rate Q _D When V _D, can be calculated by the following equation. V _N = V _D × (Q _N / Q _D ) where γ is the specific gravity of the cooling water and 992 k at 40 ° C.
g / m ³ .

By employing the above method, the rate of detecting water leaks due to minute pinholes is remarkably improved, and it is possible to discriminate between an instrument error and a tuyere damage, and the reactor condition is destabilized by early treatment. Can be avoided, and the operation trouble can be greatly reduced. In addition, the present invention is not limited to the blast furnace tuyere, and can be applied to the detection of breakage of the tuyere holder and cooling hardware of the reactor.

[0024]

According to the tuyere diagnostic method of the present invention, when the differential flow rate exceeds a predetermined set value, the differential flow rate of the cooling water when the feed water pressure is changed to change the differential pressure with the furnace pressure is changed. The point where the differential pressure becomes zero is calculated by calculating the correlation with
Whether the tuyere is damaged or an instrument error is determined from the value of the differential flow rate, and in the case of tuyere damage, the diameter of the damaged bore is estimated from the slope of the regression equation. Thus, it is possible to discriminate between an instrument error and a tuyere breakage, thereby avoiding instability of the furnace condition by early treatment and greatly contributing to a reduction in operation trouble.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory diagram of a blast furnace tuyere cooling system provided with a tuyere damage diagnosis method of the present invention.

FIG. 2 is a graph showing a relationship between a differential pressure ΔP between a tuyere tip water pressure and a furnace pressure, which indicates a water leakage amount characteristic when the tuyere is broken, and a differential flow rate ΔQ.

FIG. 3 is an explanatory diagram of data sampling timing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Water supply header 2 Tuyere 3 Water supply pipe 4 Inlet valve 5 Water supply side electromagnetic flowmeter 6, 10 Flow control valve 7 Water supply pressure gauge 8 Drainage header 9 Drainage pipe 11 Drainage side electromagnetic flowmeter 12 Drainage three-way valve 13 Outlet valve 14 Breakage diagnosis Control unit 15 Furnace pressure gauge 16 Keyboard

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F27B 1/28 C21B 7/16 C21B 7/24 F27D 21/00

Claims (1)

(57) [Claims] 1. A method for detecting a difference in output of a flow meter (differential flow rate) installed in each of a water supply pipe and a drain pipe for each cooling system of a tuyere and detecting breakage of the tuyere, wherein the differential flow rate is predetermined. When the pressure exceeds the set value, a regression equation is created by calculating the correlation with the difference flow rate of the cooling water when the pressure difference between the supply water pressure and the furnace pressure is changed . difference
Together to determine or damaged instruments error tuyere from the flow value, damage diagnosis method tuyeres if damage of the tuyere, wherein the TURMERIC line estimation of damage caliber from the slope of the regression equation.