JPH08271153A - Method and device for detecting water leakage in heating equipment - Google Patents

Abstract

PURPOSE: To provide a method and an apparatus for detecting water leakage in heating equipment wherein leakage of cooling water, etc., can be detected early even in a very small amount, and they are highly safe and secure. CONSTITUTION: A cooling water leakage detector tor an electric furnace 21 includes electromagnetic flow rate meters 23, 24, calculation means 27, detection means 28, and memory means 30. The electromagnetic flow rate meters 23, 24 detect flow rates of cooling water on outlet and inlet sides. The calculation means 27 calculates a cooling water leakage rate f, the mean value fv of the water leakage rate, and standard deviation σ on the basis of the detection result. The detection means 28 detects based upon these calculation results occurrence of leakage of cool ing water when the cooling water leakage rate f is larger than an instantaneous reference value fa or when the mean value fv of the water leakage rates is larger than a monitor reference value fb and the standard deviation σ is smaller than a standard deviation reference value σ.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating facility including an electric furnace, a metal melting furnace, or a metal melting and refining furnace, an annealing furnace, and a heat treatment furnace, and at least a part of the heating facility is a water pipe for cooling or the like. If there is a water leak in the heating equipment to detect the occurrence of water leaks, prevent accidents such as steam explosions, and ensure safety, and avoid a situation where operation is suspended or inoperable. The present invention relates to a leak detection method and device.

An electric potential furnace will be described below as an example of heating equipment.

[0003]

2. Description of the Related Art In recent years, the production amount of crude steel and the like in arc type electric furnaces has been increasing, and as the scrap steel, which is the main raw material, has increased, the furnace capacity has to be increased in order to improve the melting capacity. In addition, large electric power is being achieved. However, U of the high power factor long arc that is performed in the arc type electric furnace
In HP (ultra high power) operation, the heat load on the furnace wall and furnace ceiling is large, and in a furnace with a refractory structure using a refractory that has been used in the past, the refractory will be severely worn and the life will be shortened. Will be forced to. For this reason,
In place of the refractory structure method, water cooling of the furnace wall and furnace ceiling is carried out in order to obtain a long life.

A typical prior art of the electric furnace 1 is shown in cross section in FIG. A furnace ceiling 5 and a bottomed furnace body 2 that are generally water-cooled
The structure of the furnace wall 3 is such that the cooling water pipe 8 for water cooling is provided concentrically with respect to the direction of the central axis O of the furnace, and the inner surface of the furnace is a flat structure that does not come and go.

During the operation of such an electric furnace 1, the furnace body 2
The slag 16 is scattered from the slag layer 15 floating in the hot metal and the molten metal stored inside toward the inner surfaces of the furnace ceiling 5 and the furnace wall 3.

Water cooled furnace ceiling (hereinafter referred to as "water cooled furnace ceiling"
And a furnace wall that is water-cooled (hereinafter, “water-cooled furnace wall”)
"), Fatigue due to repeated thermal stress from a very high temperature to a low temperature (normal temperature), or physical and local contact of molten metal or scrap occurs. Therefore, mechanical, local, or sudden wear or damage is likely to occur. If water leaks into the furnace due to damage to the water-cooled furnace ceiling or water-cooled furnace wall, the amount of cooling water (cooling capacity) necessary for cooling cannot be secured, which not only shortens the life of the refractory inside the furnace but also causes water vapor. Explosion risk. When a steam explosion occurs, the equipment of the furnace is damaged, the operation is stopped, and the operator of the furnace is seriously injured. Further, when hydrogen enters the molten metal, the quality of iron-based metals may deteriorate due to hydrogen embrittlement. Furthermore, water leakage causes corrosion and heating energy loss.

Therefore, it is necessary to monitor the leakage of the cooling water, and conventionally, as a means thereof, a visual inspection is regularly performed by an operating operator of the electric furnace.

[0008]

However, there is a limit to the range in which the operator can visually inspect for water leakage in the water cooling equipment of a large-scale electric furnace by visual inspection. Especially several tens of meters
It is difficult to visually confirm a small amount of water leakage in the cooling water that flows up to ³ water.

On the other hand, in order to detect the leakage of the cooling water at an early stage by visual inspection, it is possible to shorten the inspection cycle and increase the number of operating operators. However, this goes against the streamlining of operating methods and equipment in recent years. Also,
It is impossible to inspect the inside of the heating furnace during the operation by visual inspection by the operation operator because there is high-temperature molten metal that scatters slag and the like inside the furnace.

An object of the present invention is to provide a highly safe method for detecting water leak in a heating facility, which can detect even a small amount of water leak in the heating facility early and accurately even if the amount is small. It is to provide a device.

[0011]

According to the present invention, electromagnetic flowmeters are installed on the inlet side and outlet side of a water pipe of a heating facility, and the electromagnetic flowmeter controls the inlet side flow rate and outlet side flow rate of water. The flow rate difference is detected every predetermined time, the water leak rate f is calculated based on the flow rate difference, and when the water leak rate f is equal to or more than the instantaneous reference value fa, the occurrence of water leak is detected. This is a characteristic method for detecting water leaks in heating equipment. In the present invention, the water leakage rate f
When calculating, the statistical processing is performed to calculate the average value fv of the water leakage rate and the standard deviation σ of the flow rate difference, and the standard deviation σ
Is within a predetermined range, and when the average value fv of the water leakage rate is equal to or larger than the monitoring reference value fb smaller than the instantaneous reference value fa, the occurrence of water leakage is detected. In addition, the present invention provides an electromagnetic flow meter installed on each of an inlet side and an outlet side of a water pipe of a heating facility, and in response to an output from the electromagnetic flow meter, a flow rate difference of water, a water leakage rate f, and A calculation means for calculating the standard deviation σ of the flow rate difference, a storage means for storing a predetermined reference value relating to the water leakage rate f and the standard deviation σ of the flow rate difference, and the water leakage rate f is equal to or greater than the instantaneous reference value fa. In this case, or if the standard deviation σ of the flow rate difference is within a predetermined range and the average value fv of the water leakage rate is equal to or higher than the monitoring reference value fb, a detection means for detecting the occurrence of water leakage is included. It is a water leak detection device of the heating equipment which is a feature.

[0012]

According to the present invention, the electromagnetic flow meters are installed on the inlet side and the outlet side of the water pipe for cooling, which is provided mainly for cooling the furnace wall and the furnace ceiling of the heating equipment. The electromagnetic flow meter detects the flow rate difference ΔF between the inflow side flow rate F1 and the outflow side flow rate F0 of the water flowing through the water pipe every predetermined time. Since the water entering from the inlet side flows out from the outlet side of the water pipe, the flow rate difference ΔF between the inlet side flow rate F1 and the outlet side flow rate F0 represents the amount of water leakage.

Based on the detected flow rate difference ΔF, the water leakage rate f
Is calculated. The water leakage rate f is represented by the ratio of the flow rate difference ΔF to the inlet side flow rate F1. When the water leakage rate f is equal to or greater than a predetermined instantaneous reference value fa, it is determined that a large water leakage has occurred instantaneously, so that the occurrence of water leakage is detected early. be able to.

Further, according to the present invention, when the water leakage rate f is calculated, statistical processing is performed to calculate the average value fv of the water leakage rate and the standard deviation σ of the flow rate difference. When the standard deviation σ of the flow rate difference is within the predetermined range, it is confirmed that the variation of the water leakage rate f due to noise or the like is small and the accuracy of the flow rate difference is high. Therefore, the standard deviation σ of the flow rate difference is within a predetermined range, and the average value fv of the water leakage rate is smaller than the predetermined instantaneous reference value fa, but the monitoring reference value f
When it becomes b or more, it means that water leakage is occurring at a constant rate. In this way, the occurrence of a small amount of continuous water leakage can be detected early and reliably.

Further, according to the present invention, the water leak detection device for heating equipment includes an electromagnetic flow meter, a calculation means, a storage means and a detection means. The electromagnetic flowmeters are installed on the inlet side and the outlet side of a pipe for cooling water, which is provided mainly for cooling the furnace wall and the furnace ceiling of the heating equipment.

The calculating means is responsive to the output from the electromagnetic flowmeter, a flow rate difference ΔF between an inlet side flow rate F1 and an outlet side flow rate F0 of water flowing through the water pipe, and a flow rate difference ΔF with respect to the inlet side flow rate F1.
The water leak rate f and the standard deviation σ of the flow rate difference are calculated. This calculation is performed multiple times at predetermined time intervals.

The storage means stores predetermined reference values such as the instantaneous reference value fa and the monitoring reference value fb. Instantaneous reference value f
The a and the monitoring reference value fb are set in advance based on the experimental result regarding the water leakage rate f and the standard deviation σ of the flow rate difference.

The detection means detects the occurrence of water leakage.
When the calculated water leak rate f is equal to or greater than the instantaneous reference value fa, or the standard deviation σ of the flow rate difference is within a predetermined range stored in the storage means, and the average value of the water leak rate fv.
Is smaller than the instantaneous reference value fa but becomes equal to or larger than the monitoring reference value fb.

Thus, not only when a large amount of water leaks momentarily, but also when a small amount of water leak occurs at a constant rate, the cooling water can be promptly, easily, reliably and rationally. Water leaks can be detected.

[0020]

FIG. 1 is a block diagram showing the electrical construction of a cooling water leakage detection device for an arc type electric furnace, which is an example of heating equipment, as an embodiment of the present invention. A cooling water pipe 22 is arranged in the electric furnace 21 to cool the furnace wall 1a and the furnace ceiling 1b. The cooling water supplied from the water supply header 25 flows through the inlet side of the cooling water pipe 22 and then flows through the cooling water pipe 22 arranged in the electric furnace 21.
It is guided to the drainage manifold 26 through the outlet side of 2.

The cooling water leak detector is an electromagnetic flow meter 2
3, 24, calculation means 27, detection means 28, and storage means 30
It is comprised including. At least the calculation means 27 and the detection means 28 are realized by the program operation of the computer device. The electromagnetic flow meter 23 is the cooling water pipe 22.
Is installed on the inlet side of and the inlet flow rate F1 of the cooling water is detected. The electromagnetic flow meter 24 is installed on the outlet side of the cooling water pipe 22 and detects the outlet side flow rate F0 of the cooling water. These detections are performed by n (n = 20) at every predetermined time t (t = 10 to 15 seconds).
~ 40) times. The electromagnetic flowmeters 23, 24 convert the flow rates of the cooling water on the inlet side and the cooling water on the outlet side into electrical signals according to Faraday's law of electromagnetic induction, and these electrical signals are input to a computing means 27 realized by a computer or the like. It
The calculation means 27 detects the flow rate difference ΔF and the cooling water leakage rate f based on both the input signal indicating the detection result of the input flow rate F1 and the input signal indicating the detection result of the output flow rate F0. Only the number corresponding to the number of times n is calculated. From the detection result of n times, the average value fv and the standard deviation σ of the cooling water leakage rate are calculated.

On the other hand, the storage means 30 stores predetermined reference values fa, fb, σb regarding the cooling water leakage rate f and the standard deviation σ which are set on the basis of experimental results and the like.
The instantaneous reference value fa is a reference value to be applied when the water leakage rate f is high. The monitoring reference value fb is a reference value to be applied when the water leakage rate is low, and is a value smaller than the instantaneous reference value fa. The standard deviation reference value σb is a reference value for determining whether or not the standard deviation σ is within a predetermined range when the water leakage rate f is low.

The detection means 28 uses these reference values fa, f.
b and σb are read from the storage means 30 and compared with the calculated average value fv of the cooling water leakage rate and the standard deviation σ, respectively. The detecting means 28 detects water leakage based on the compared results. That is, when the cooling water leakage rate f is the instantaneous reference value fa or more, or the average value fv of the water leakage rates is the monitoring reference value fb or more and the standard deviation σ is greater than the standard deviation reference value σb. If it is also small, it is detected that there is a water leak, and an alarm is output by the alarm device 29. Electric furnace 2
When the alarm is output, the operation operator No. 1 stops the power transmission or stops the operation. It is also possible to automatically perform these operations.

Next, the calculation process of the flow rate difference ΔF, the cooling water leakage rate f, the average value fv of the water leakage rate, and the standard deviation σ will be specifically described. The cooling water flow rate difference ΔF is determined by the cooling water pipe 22.
It is expressed by the following first equation using the inlet side flow rate F1 and the outlet side flow rate F0.

ΔF = F1−F0 (m ³ / n) (1) Based on the result of the first expression, the cooling water leakage rate f is expressed by the following second expression.

[0026]

[Equation 1]

The flow rate difference ΔF and the cooling water leakage rate f are n (n = 20 to 40) at every predetermined time t (t = 10 to 15 seconds).
It is calculated by the rate of times. Therefore, the flow rate difference Δ calculated n times
Using F and the cooling water leakage rate f, the standard deviation σ and the average value fv of the water leakage rate are calculated by the following third equation and fourth equation, respectively.
It is represented by a formula.

[0028]

[Equation 2]

ΔF, f, f calculated in this way
v, σ and predetermined reference values fa, fb, σb are compared,
Occurrence of water leakage is detected. If the water leakage rate f is high, the instantaneous reference value fa is applied. That is, when f ≧ fa, it is detected that water leakage has occurred.

Although the water leakage rate f is low, the monitoring reference value fb and the standard deviation reference value σb for the average value fv are applied in case the water leakage occurs at a constant rate. That is, it is detected that water leakage has occurred when fv ≧ fb and σ ≦ σb.

FIG. 2 is a flow chart showing a conceptual flow of calculation used in the cooling water leakage detection method of the present invention. In step n1, the electromagnetic flow meter 23 detects the inlet-side flow rate F1 of the cooling water pipe 22, and in step n2, the electromagnetic flow meter 24 detects the outlet-side flow rate F0 of the cooling water pipe 22. In step n3, the calculation means 27
At, the flow rate difference ΔF is calculated based on the detected inlet side flow rate F1 and outlet side flow rate F0. Further, the cooling water leakage rate f is calculated in step n4 based on the flow rate difference ΔF,
In step n5, the standard deviation σ is calculated. Step n6
Then, the detection means 28 compares the predetermined reference values fa, fb, σb and f, fv, σ stored in the storage means 30 with each other, and detects whether or not there is water leakage from the comparison result. When water leakage is detected, an alarm is output from the alarm device 29 in step n7 to notify that water leakage has occurred.

This situation will be described in a more detailed flowchart. FIG. 3 is a flow chart for explaining the cooling water leakage detection method of the electric furnace of the present invention. In step k1, the parameter N corresponding to the number of times n of detection of the cooling water flow rate is set to 0 as an initial setting. In step k2, the inlet flow rate F1 and the outlet flow rate F0 of the cooling water pipe 22 are detected by the electromagnetic flow meters 23 and 24. In step k3, the calculating means 27 calculates the flow rate difference ΔF based on the inlet side flow rate F1 and the outlet side flow rate F0. In step k4,
Further, the calculating means 27 calculates the cooling water leakage rate f using the flow rate difference ΔF.

In step k5, the detection means 28 compares the instantaneous reference value fa previously stored in the storage means 30 with the cooling water leakage rate f. When the cooling water leakage rate f is equal to or greater than the instantaneous reference value fa, it is determined that a large water leakage has occurred instantaneously, so the process proceeds to step k11, and the first
An alarm will be issued to let you know that a major water leak has occurred. When the cooling water leakage rate f is smaller than the instantaneous reference value fa, it is considered that no large water leakage has occurred instantaneously, so the process proceeds to step k6. In step k6, the parameter N for the number of times the cooling water flow rate is detected is increased by one. At step k7, it is determined whether the parameter N is a predetermined number of times, for example, 30 or more. If it is determined that the number of times is less than the predetermined number of times, the process returns to step k2, and the cooling water inlet flow rate F
1 and the outlet flow rate F0 are detected. If it is determined that the parameter N has exceeded the predetermined number of times, step k
8, the calculating means 27 calculates the average fv and the standard deviation σ of the water leakage rate. In step k9, the monitoring reference value fb and the standard deviation reference value σb stored in the storage means 30 in advance in the detection means 28 are compared with the average value fv and the standard deviation σ of the cooling water leakage rate, respectively. If it is determined that fv ≧ fb and σ ≦ σb are not satisfied, it is determined that a small water leak has not occurred, and therefore the process returns to step k1 and the cooling water flow rate is detected a predetermined number of times again. If it is determined that fv ≧ fb and σ ≦ σb, it is determined that a small water leak is occurring at a certain rate without fail. Therefore, the process proceeds to step k10, and the second alarm is output to detect the small water leak. Tell what's happening. Thus, a series of operations is completed.

Predetermined reference values fa, fb, σb to be compared with the water leakage rate f, the average value fv of the water leakage rate, and the standard deviation σ.
The specific numerical value of is determined from the experimental result of the water leak test in consideration of the noise generated in the factory, the accuracy of the electromagnetic flow meters 23 and 24, and the like. FIG. 4 shows the correlation characteristic between the water leakage rate f and the water leakage amount. From this experimental result, for example, based on the water leak rate that can be detected instantaneously, the instantaneous reference value fa
= 2.4 (%) and the monitoring reference value fb = 1.6 (%). Further, when the monitoring reference value fb is applied, the standard deviation σ is required to be within a predetermined range, for example, σ ≦ σb. This is because the level difference between the noise level generated in the factory due to the difference in the operating conditions of the furnace and the signal level for detecting the flow rate difference of the cooling water pipe 22 is small, so it is erroneously determined that there is a water leak and an alarm is issued. This is because it is necessary to perform statistical processing in order to prevent issuance.

Since it is detected stepwise whether or not there is a water leak depending on the state of the water leak, it is possible to detect the water leak early and reliably.
It is possible to ensure safety. Further, the efficiency of detecting the water leak is higher than that in the case of visually detecting the water leak.

In the present embodiment, the detection of water leak and the alarm are divided into two stages according to the state of water leak, but three stages are taken into consideration in consideration of the ratio between the noise level and the signal level, and further. Can be performed in more steps.

The first alarm and the second alarm in this embodiment may be distinguished by the difference in the alarm sound, or the alarm lamp may be turned on instead of issuing the alarm. In this case, the water leak can be notified step by step by turning on an alarm lamp of a different color depending on the state of the water leak. Further, it is possible to automatically stop the power transmission and the operation.

Although the water leak detection of the heating equipment has been described above centering on the electric furnace, the present invention can be similarly applied to other types of heating equipment. In a facility that uses fuel, the supply of fuel can be cut off when the occurrence of water leakage is detected.

[0039]

As described above, according to the present invention, it is possible to detect a large water leak that occurs instantaneously and accurately with high accuracy, and perform alarm output, heating stop, operation stop, etc. It is possible to extend the life of expensive refractories, prevent accidents caused by water leaks, and enable safe continuous operation. As a result, it is possible to reduce the load of the regular visual inspection work and ensure the safety of the work. Furthermore, the quality and yield of products that use heating equipment are improved, the risk of adversely affecting the previous and subsequent processes is reduced, equipment investment and running costs are reduced, and overall maintenance-free and cost reduction are achieved. You can

Further, according to the present invention, since a small amount of water leakage continuously occurring can be detected early and accurately with certainty, the occurrence of steam explosion can be prevented and the life of the heating equipment can be shortened. Can be extended.

Further, according to the present invention, since the water flow rate is electrically detected by using the electromagnetic flow meter, the water leak can be detected quickly, easily, accurately and surely, and the operation can be performed. It is possible to reduce the work load on the operator and ensure work safety.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration of a cooling water leakage detection device for an electric furnace according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a conceptual flow of calculation used in the water leak detection method by the apparatus of the embodiment of FIG.

3 is a flow chart for explaining a cooling water leakage detection method by the apparatus of the embodiment of FIG.

FIG. 4 is a graph showing a correlation characteristic between a water leakage rate and a water leakage amount based on an experimental result.

FIG. 5 is a cross-sectional view showing a typical configuration of an electric furnace.

[Explanation of symbols]

 1a Furnace wall 1b Furnace ceiling 21 Electric furnace 22 Cooling water piping 23, 24 Electromagnetic flow meter 25 Water supply header 26 Drainage manifold 27 Computing means 28 Detecting means 29 Alarming device 30 Storage means

Claims (3)

[Claims] 1. An electromagnetic flow meter is installed on the inlet side and the outlet side of a water pipe of a heating facility, and the flow rate difference between the inlet side flow rate and the outlet side flow rate of water is set at predetermined intervals by the electromagnetic flow meter. Water leak rate f is calculated based on the flow rate difference, and when the water leak rate f is equal to or greater than the instantaneous reference value fa, water leak occurrence is detected. Detection method. 2. When calculating the water leak rate f, statistical processing is performed to calculate an average value fv of the water leak rate and a standard deviation σ of the flow rate difference, and the standard deviation σ is within a predetermined range. 2. The heating according to claim 1, wherein when the average value fv of the water leakage rate is equal to or more than a monitoring reference value fb smaller than the instantaneous reference value fa, the water leakage occurrence is detected. Water leak detection method for equipment. 3. An electromagnetic flow meter installed on each of an inlet side and an outlet side of a water pipe of a heating facility, and in response to an output from the electromagnetic flow meter, a water flow rate difference, a water leakage rate f, and A calculation means for calculating the standard deviation σ of the flow rate difference, a storage means for storing a predetermined reference value relating to the water leak rate f and the standard deviation σ of the flow rate difference, and the water leak rate f being equal to or greater than the instantaneous reference value fa. In the case, or when the standard deviation σ of the flow rate difference is within a predetermined range and the average value fv of the water leakage rate is equal to or higher than the monitoring reference value fb,
A water leak detection device for heating equipment, comprising: a detection means for detecting the occurrence of water leak.