JPH08303699A - Method and apparatus for detecting abnormality in fluid transportation piping system - Google Patents

Abstract

PURPOSE: To enable abnormalities or failures of a flow meter and the accident of leakage of a piping to be discriminated and detected by finding the ratio of the flow rate total value on the outflow side in relation to the flow rate total value to be measured on the inflow side and judging abnormalities of a flow meter when the ratio of the flow rate satisfies the specified relationship. CONSTITUTION: When an abnormality detecting device is applied to a blast furnace gas transport piping system, generation flow meters 11, 12 are attached to inflow pipes p1 , p2 extending to a blast furnace gas transporting pipe line P, and consumption side flow meters 13 to 17 are attached to outflow pipes p3 to p7 . The generation side flow rate total values ΣF1 , ΣF0 obtained from a generation side flow rate calculator 20 and a consumption side flow rate calculator 21 are input, the flow rate ratio Fr is found by a flow rate calculator 22, and abnormalities of the flow meters are judged when the flow rate Fr satisfies the formula Fr>1-ε, or 1-ε>Fr>=1-λ. On the other hand, when the flow rate ratio Fr satisfies the formula Fr<1-λ, leakage caused by damage of the pipe line of a piping system is judged. The letter ε is indicates properties of fluid and the error ratio to be determined from the pipe diameter, and the letter λ indicates the ratio of the leakage amount in relation to the inflow side total flow rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for detecting abnormality in a fluid transportation piping system.

[0002]

2. Description of the Related Art Generally, in a piping system for transporting a fluid such as gas or liquid, a flow meter is attached to each point of a transportation pipe system such as an inflow pipe for receiving the fluid and an outflow pipe for communicating the fluid with the inflow pipe. The flow rate is measured, monitored or controlled. The quality control of these flowmeters is generally confirmed by a precision check such as periodic scale inspections performed by maintenance personnel, but it is complicated due to the wide variety of fluid transportation piping systems, and many flowrates are involved. If a meter is provided, it causes an increase in maintenance load and an increase in maintenance and inspection personnel. Further, when checking the accuracy of the flow meter, the flow rate signal from the flow meter cannot be transmitted, which hinders the operation of the plant or the like.

On the other hand, regarding the method of detecting fluid leakage due to pipe breakage or cracks, the total flow rate ΣF _I on the inflow pipe side and the total flow rate ΣF _O on the outflow pipe side are compared and the inflow side flow rate is compared. Total value ΣF _I is outflow side total flow value ΣF
Method of determining a leakage occurs when it becomes larger than _O have been proposed (e.g., Japanese Utility Model 54-70492, JP 56 - 52700 No., see JP Hei 4-363638).

[0004]

However, the above-described method for detecting fluid leakage based on the flow rate difference between the inflow pipe side and the outflow pipe side has the following problems. (1) Even if a flow rate measurement error within the normal error range occurs, it may be mistakenly determined that fluid leakage has occurred, and it may be necessary to take excessive measures. (2) The error due to the amount of leakage from the pipe and the deviation of the measurement span of the flow meter also changes in proportion to the increase / decrease in the flow rate. thing. (3) It is judged that the probability of occurrence of a pipe leakage accident is generally lower than that of an abnormality or failure of the flowmeter, but regarding the urgency of countermeasures, a pipe leakage accident is more likely to cause an abnormality or failure of the flowmeter. It is considered to be expensive. However, in the conventional method, the error of the flow meter in the normal range is not taken into consideration, and the abnormality or failure of the flow meter and the pipe leakage accident are not distinguished,
An urgent response is always needed. As a result, the maintenance load increases and many maintenance personnel are required.

The present invention has been made in order to solve the above-mentioned problems of the prior art. In consideration of a normal error of a flow meter, such an error and an abnormality or failure of the flow meter are considered. An object of the present invention is to provide a method and an apparatus for detecting an abnormality in a fluid transportation piping system, which can detect a piping leakage accident separately and reduce the maintenance load of the flowmeter, and can surely cope with the piping leakage accident. And

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a flow rate through a flow meter attached to the inflow side and the outflow side of a fluid transportation piping system for inflowing one or more fluids and outflowing one or more fluids. In the method for detecting an abnormality in a fluid transportation piping system in which each of the above is measured, the ratio F _{r of the} total flow rate on the outflow side to the total flow rate measured on the inflow side is obtained, and the flow rate ratio F _r is calculated by the following equation (1) or When the equation (2) is satisfied, it is judged that the flowmeter is abnormal, and when the flow rate ratio _Fr satisfies the following equation (3), it is judged that the leakage is caused by the pipe breakage of the fluid transportation piping system. This is the abnormality detection method.

F _r > 1 + ε ………… (1) 1-ε> F _r ≧ 1-λ ………… (2) F _r <1-λ ………… (3) Here, ε is an error ratio determined by the characteristics of the fluid, the pipe diameter, the type and characteristics of the flow rate detector, etc., and is a constant smaller than 1 which is empirically determined.

Λ: a ratio of a leakage amount to a limit at which emergency measures are not taken even if there is a leak from a pipe, and a constant greater than ε and less than 1 which is empirically determined. The error ratio ε is 0.2 and the leakage amount ratio λ is 0.5.
It is good to do. Further, in the present invention, in a fluid transportation piping system to which one or more fluid inflow pipes and one or more fluid outflow pipes are connected, the flowmeters attached to the inflow pipe and the outflow pipe respectively An abnormality detection device for a fluid transportation piping system for measuring a flow rate, comprising: a flow rate ratio calculating means for obtaining a ratio F _r of a total flow rate value measured in the outflow pipe to a total flow rate value measured in the inflow pipe, Flow rate ratio F obtained by the flow rate ratio calculating means
_{When r} is input and a comparison calculation is performed using a preset error ratio ε and a leakage amount ratio λ, when the flow rate ratio F _r satisfies the following equation (1) or equation (2), the flowmeter is abnormal. An abnormality detecting device for a fluid transportation piping system, comprising: an alarm and comparing / warning means for issuing a pipe breakage leakage alarm when the flow rate ratio F _r satisfies the following expression (3).

F _r > 1 + ε ………… (1) 1-ε> F _r ≧ 1-λ ………… (2) F _r <1-λ ………… (3) Where ε is an error ratio determined by the characteristics of the fluid, the pipe diameter, the type and characteristics of the flow rate detector, etc., and is a constant smaller than 1 which is empirically determined.

Λ: A ratio of the leakage amount of the limit at which emergency measures are not taken even if there is a leak from the pipe to the total flow rate on the inflow side, which is a constant greater than ε and less than 1 which is empirically determined. The error ratio ε is 0.2 and the leakage amount ratio λ is 0.5.
It is good to do.

[0011]

In general, the measurement accuracy of the flowmeter changes depending on the characteristics such as the temperature, pressure and viscosity of the fluid, the pipe diameter, the type of the flowmeter and the measurement span thereof. Since it is easy to measure the temperature and pressure of a fluid, in a fluid transport piping system where the temperature and pressure change depending on the location, measure the temperature and pressure together with the flow rate, and under certain temperature and pressure conditions. The value corrected to the flow rate value of is used.

Even when such temperature / pressure correction is performed, a flow rate measurement error occurs due to other factors. Therefore, the flow rate measurement value in the granular transport piping system is used to detect the fluid flow due to the failure of the flow meter or the damage to the piping. In the case of detecting the leakage as an abnormality, the probability of false detection becomes very high unless the flow measurement error in such a normal range is taken into consideration. In addition, the error due to the amount of leakage from the pipe and the deviation of the detection span of the flow meter also changes in proportion to the increase / decrease in the flow rate. Occurs.

Therefore, in the present invention, the ratio F _r of the total value of the flow rate measurement values on the outflow side to the total value of the flow rate measurement values on the inflow side is obtained and made dimensionless, so that the above-mentioned influence of the increase or decrease of the flow rate can be reduced. It can be lost. Furthermore, the characteristics of the fluid allowed for the flow rate ratio F _r ,
If the error ratio in the normal range determined by the pipe diameter and the type and characteristics of the flow rate detector is ε (however, ε is a constant smaller than 1), the flowmeter will fail or be abnormal (normal errors will not be abnormal) or piping. If there is no leakage due to damage to the
The formula holds.

1-ε ≦ F _r ≦ 1 + ε (4) Next, if a failure or abnormality of the flow meter occurs,
Equation (5) or equation (6) holds. F _r > 1 + ε ………… (5) 1-ε> F _r ………… (6) Here, if the equation (5) holds, the total flow rate on the outflow side is Since it is larger than the total flow rate, there is no leakage due to pipe damage, and it may be determined that the flowmeter is faulty or abnormal.

On the other hand, when the equation (6) is satisfied, the total flow rate on the outflow side is smaller than the total flow rate on the inflow side. Therefore, in addition to the failure or abnormality of the flowmeter, there is leakage due to pipe damage. obtain. Therefore, even if there is a leak due to pipe breakage, it is ignored, and the leak amount is empirically determined by deciding the ratio of the limit leak amount to the total flow rate on the inflow side, which is regarded as an abnormality of the flowmeter and emergency response is not performed. If the ratio is λ (where λ is a constant larger than ε and smaller than 1), the flow rate ratio F _r is
When the formula (7) is satisfied, firstly, it is judged that the flowmeter is faulty or abnormal.

1-ε> F _r ≧ 1-λ (7) Therefore, when the flow rate ratio F _r satisfies the following equation (8),
It may be determined that the leak is due to pipe damage, and emergency measures should be taken. 1-λ> F _r (8) As described above, according to the present invention, when the flowmeter is within the normal error range, when the flowmeter is out of order, or when there is an abnormality, the pipe is damaged. In the case of the latter two,
Since each alarm is sent out, for example, when the flowmeter is within the normal error range, it is possible to omit maintenance of the flowmeter, reduce maintenance load, and reduce the number of maintenance personnel. It is possible to plan. In addition, in the case where a certain amount of leakage has actually occurred due to pipe breakage, and depending on the magnitude of the flow rate ratio F _r , there may be cases where a flow meter abnormality alarm is issued due to a flow meter abnormality range. In this case, There is a high possibility that a leak due to pipe damage will be found if the flowmeter is checked and checked for abnormal points, so there is no practical problem.

Next, industrial water and by-product gas (for example, blast furnace gas, coke oven gas, etc.) in an ordinary steelmaking plant, etc.
When the present invention is applied to the fluid transportation piping system, the error ratio ε is preferably set to about 0.2. This is based on past experience, and an error of 20% or more has been used as a standard for many years as a criterion for requesting maintenance and inspection personnel from plant operators to repair and repair flowmeters. This has not caused any particular problems.

Further, when the present invention is applied to the above-mentioned fluid transportation piping system, it is preferable that the leakage amount ratio λ is about 0.5. This is the normal error ratio ε of the flowmeter as above.
When set to about 0.2, depending on the malfunction or abnormality of the flow meter,
For example, assuming that the flowmeter on the inflow side has no error, the flowmeter on the outflow side suddenly indicates less than half of the actual value, or conversely, assuming that the flowmeter on the outflow side has no error, It is based on the empirical fact that a sudden abnormal phenomenon such as sudden indication of the flowmeter on the inflow side that is more than the actual value does not occur.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an embodiment in which the present invention is applied to a blast furnace gas transportation piping system of an iron manufacturing plant. In this figure, reference numerals 1 and 2 denote blast furnaces that generate blast furnace gas, which are connected by a blast furnace gas transport line P. 3-
7 is a blast furnace gas consumption facility, 3 is a blast furnace gas diffusion tower, 4 is a hot blast stove, 5 is a gas turbine power generation facility, 6 is a billet heating furnace, 7
Are other blast furnace gas consuming facilities, all of which are connected to the blast furnace gas transportation pipeline P. Blast furnace gas diffusion tower 3
A gas diffusion valve 8 is attached to the tip of the.

Reference numeral 9 is a gas holder connected to the blast furnace gas transportation pipeline P for storing blast furnace gas. The blast furnaces 1 and 2 and the blast furnace gas diffusion tower 3 which is a blast furnace gas consuming facility, the hot blast stove 4, and the gas turbine power generation equipment. 5, it serves as a buffer between the billet heating furnace 6 and other blast furnace gas consuming equipment 7, and plays a role of both the blast furnace gas consuming equipment and the blast furnace gas generating equipment depending on the time. That is, the blast furnace gas consumption facility is used while the blast furnace gas storage amount is increasing in the gas holder 9, and the blast furnace gas generation facility is used when the blast furnace gas storage amount is decreasing.

Reference numerals 11 and 12 denote inflow pipes p to the blast furnace gas transport pipe line P.
₁ and p ₂ are flowmeters on the generating side, and 13 to 17 are flowmeters on the consuming side, which are installed on the outflow pipes p _{3 to} p ₇ from the blast furnace gas transport pipeline P. The measured blast furnace gas flows in the direction indicated by the arrow. Reference numeral 18 is a level meter attached to the gas holder 9. Reference numeral 19 denotes a gas holder inlet / outlet flow rate calculating unit, which calculates the flow-in / out pipe p to / from the gas holder 9 from the time change of the level signal of the level meter 18 and the holder cross-sectional area of the gas holder 9.
Calculate the blast furnace gas flow in and out via ₈ .

Reference numeral 20 denotes the flow of the blast furnace gas generation side flow meters 11 and 12.
Quantity measurement value F₁, F₂Enter and generate by the following formula (9)
Side total flow ΣF_IIs a source side flow rate calculator that calculates
It ΣF_I= F₁+ F₂ ……………… (9) 21 is the flow rate measurement value from the blast furnace gas consumption side flowmeters 13 to 17.
F₃~ F₇And gas holder in / out flow rate calculator 18
Input flow rate F₈Enter the total flow rate on the consumption side ΣF _OBelow
This is a consumption-side flow rate calculator that calculates using equation (10).

ΣF _O = F ₃ + F ₄ + F ₅ + F ₆ + F ₇ + F ₈ (10) Note that the inlet / outlet flow rate value F ₈ is at the time of outflow from the blast furnace gas transport pipe P, that is, in the gas holder 9. It is defined as having a "+" (plus) sign when the level rises, and a "-" (minus) sign when the gas holder 9 flows down, that is, when the level of the gas holder 9 falls.

22 is the input of the total flow rate ΣF _I of the generating side and the total flow rate ΣF _O of the generating side from the flow rate calculating unit 20 of the generating side and the flow rate calculating unit of the consuming side 21, and the flow rate ratio F _r is _expressed by the following equation (11). This is a flow rate ratio calculator obtained by F _r = ΣF _O / ΣF _I = (F ₃ + F ₄ + F ₅ + F ₆ + F ₇ + F ₈ ) / (F ₁ + F ₂ ) ……………… (11) 23 is a comparison calculator and a flow ratio calculator 22, a constant setter 24 that sets the error ratio ε, and a constant setter that sets the leakage amount ratio λ
25 are connected to each other, and comparison calculation is performed using the flow rate ratio F _r input from the flow rate ratio calculator 22 and the error ratio ε and the leakage amount ratio λ given from the constant setters 24 and 25.
When the flow rate ratio F _r satisfies (12) or (13), a flow meter failure / abnormality alarm is issued via the alarm device 26, and when the flow rate ratio F _r satisfies (14), the pipe breakage leaks as well. Generate an alarm for the occurrence.

F _r > 1 + ε ………… (12) 1-ε> F _r ≧ 1-λ ………… (13) F _r <1-λ ………… (14) In this embodiment, since it is premised that the temperature and pressure hardly change at the site of the blast furnace gas transportation pipeline P, the temperature and pressure are not corrected for the measured flow rate value.

The inflow / outflow flow rate value F ₈ representing the inflow / outflow amount at the gas holder 9 is a “+” sign when the level of the gas holder 9 rises, and a “−” when the level of the gas holder 9 drops.
Although it is described as having the sign of “+”, if it is defined so as to have the sign of “+” on the outflow side from the blast furnace gas transportation pipeline P, that is, the blast furnace gas consumption side, the following (15) to (17) )
The flow rate ratio F _r can be calculated in the same manner using the equation.

ΣF _I = F ₁ + F ₂ −F ₈ ………… (15) ΣF _O = F ₃ + F ₄ + F ₅ + F ₆ + F ₇ ………… (16) F _r = ΣF _O / ΣF _I = (F ₃ + F ₄ + F ₅ + F ₆ + F ₇ ) / (F ₁ + F ₂ −F ₈ ) ……………… (17) In addition, this inlet / outlet flow rate value F ₈ is used as the blast furnace gas transportation pipeline P When the gas holder level is increased when the gas holder level rises when the gas flows out from the fuel cell, and when the gas holder level is lowered when the gas holder level drops when the gas flows into the blast furnace gas transport pipeline P, ΣF _I = F ₁ + F ₂ + F ₈ ………… (18) ΣF _O = F ₃ + F ₄ + F ₅ + F ₆ + F ₇ ………… (19) F _r = ΣF _O / ΣF _I = (F ₃ + F ₄ + F ₅ + F ₆ + F ₇ ) / (F ₁ + F ₂ + F ₈ ) ……………… (20), or ΣF _I = F ₁ + F ₂ ………… (18a) ΣF _O ＝ _{F 3 + F 4 + F 5} + F 6 + F 7 _{F 8 .................. (19a) F r} = ΣF O / ΣF I = (F 3 + F 4 + F 5 + F 6 + F 7 -F 8) / (F 1 + F 2) .................. (20a ).

Further, in the above-mentioned embodiment, the inlet / outlet flow rate value F ₈ is calculated from the time change of the level detection value by the level meter 18 and the holder cross-sectional area. Instead of this, a bidirectional measurement type flow meter is used. Alternatively, two unidirectional flowmeters may be provided with their directions turned to each other. Also in this case, as in the case of the above-described embodiment, the sign of "+" is given to the flow in one direction, and the sign of "-" is given to the flow in the opposite direction.
If the definition is given with the sign of, the concept is the same as the above, and the expressions (9) to (11), (15) to (17), (18) to (20), and (18
It may be calculated using any one of the formulas a) to (20a).

Targeting a steelmaking plant having the same construction as shown in FIG. 1, the formulas (9) to (11) are added to the formulas of the generator side flow rate calculator 20, the consumer side flow rate calculator 21 and the flow rate ratio calculator 22. )
It is a comparison operation expression using an expression and used in the comparison operation unit 23.
The constants of the equations (12) to (14) were set to ε = 0.2 and λ = 0.5, respectively, and an experiment for detecting an abnormality in the blast furnace gas transport pipeline P was conducted for one year.

During this period, the abnormality (failure) alarm of the flowmeter was transmitted three times in total, and as a result of the maintenance personnel inspecting the flowmeter each time, a failure of the flowmeter occurred in any case. found. Then, after taking action for repairing the trouble, the alarm was no longer issued. Moreover, no leak warning was issued due to pipe damage. Further, as shown in FIG. 2, a bypass pipe p _B is connected around the flow meter 13 attached to the blast furnace gas diffusion tower 3, and front and rear valves V _I ,
V _O and bypass valve V _B are attached, front and rear valves V _I and V _O are closed, bypass valve V _B is opened, gas diffusion valve 8 at the tip is fully opened, and flow meter 13 is bypassed to bypass pipe p _B. Experiments were conducted to maximize gas emissions.
As a result, the flow rate ratio F _r dropped to 0.4. Since the set value of the leakage ratio λ at this time is 0.5, _Fr = 0.4 <1-λ = 0.5 and the condition that satisfies the above equation (14) occurs, and the piping Leakage due to rupture could be detected.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments, and it is understood that various modifications are included within the scope of the gist of the constitution of the present invention. There is no end.

[0032]

As described above, according to the present invention,
When the flowmeter abnormality alarm is issued, maintenance of the flowmeter is detected by distinguishing the abnormality in the fluid transportation piping system from the failure or abnormality of the flowmeter and the case of large leakage due to pipe damage. It is possible to reduce the maintenance load and the number of maintenance and inspection personnel. In addition, leaks due to pipe breakage can be detected in a timely manner, which enables swift response and treatment and contributes to the safety of the equipment.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment in which the present invention is applied to a blast furnace gas transportation piping system of an iron mill.

FIG. 2 is an explanatory diagram of an apparatus used in an experiment of the present invention.

[Explanation of symbols]

1, blast furnace 3 blast furnace gas diffusion tower 4 hot blast stove 5 gas turbine power generation equipment 6 steel slab heating furnace 7 other blast furnace gas consumption equipment 8 gas diffusion valve 9 gas holder 11, 12 generation side flow meter (flow meter) 13 to 17 consumption Side flow meter (flow meter) 18 Level meter 19 Gas holder inlet / outlet flow rate calculator 20 Source side flow rate calculator 21 Consumption side flow rate calculator 22 Flow rate ratio calculator (flow ratio calculator) 23 Comparison calculator (comparison / alarm means) 24 , 25 constant setting device 26 alarms (comparing and warning means) P blast furnace gas pipeline (fluid transport pipe system) p _1, p ₂ inlet tube p ₃ ~p ₇ outflow pipe p ₈ outflow pipe p _B bypass pipe V _I Front valve V _O Rear valve V _B Bypass valve

Claims (4)

[Claims] 1. Fluid transportation in which one or more fluids flow in and one or more fluids flow out, and the flow rate of which is measured via a flow meter attached to the inflow side and the outflow side of a fluid transportation piping system, respectively. in the abnormality detection method of the piping system, to determine the specific F _r of the total flow rate value at the outlet side to the flow rate sum measured at the inlet side, the flow rate ratio F _r is the following
When the formula (1) or the formula (2) is satisfied, it is judged that the flow meter is abnormal, and when the flow rate ratio _Fr satisfies the following formula (3), it is judged that the leakage is caused by the breakage of the fluid transportation piping system. Method for detecting abnormality in fluid transportation piping system. F _r > 1 + ε ………… (1) 1-ε> F _r ≧ 1-λ ………… (2) F _r <1-λ ………… (3) where ε: An error ratio determined by the characteristics of the fluid, the diameter of the pipe, the type and characteristics of the flow rate detector, etc., which is an empirically determined constant smaller than 1. λ: A ratio of the leakage amount at the limit where emergency measures are not taken even if there is a leak from the pipe to the total flow rate value on the inflow side, which is a constant larger than ε which is empirically determined and smaller than 1. 2. The abnormality detection method for a fluid transportation piping system according to claim 1, wherein the error ratio ε is 0.2 and the leakage amount ratio λ is 0.5. 3. An inflow pipe for one or more fluids and 1
Or, in a fluid transportation piping system to which two or more fluid outflow pipes are connected, an abnormality detection device for a fluid transportation piping system, wherein respective flow rates are measured by flowmeters attached to the inflow pipe and the outflow pipe, The flow rate ratio calculating means for obtaining the ratio F _{r of the} total flow rate value measured in the outflow pipe to the total flow rate value measured in the inflow pipe and the flow rate ratio F _r obtained by the flow rate ratio calculating means are input. , A comparison is made using a preset error ratio ε and a leakage amount ratio λ, and the flow rate ratio F _r is as follows (1)
A comparison / warning means is provided, which issues a flowmeter abnormality alarm when the formula (2) is satisfied, and a pipe breakage leak alarm when the flow rate ratio _Fr satisfies the following formula (3). An abnormality detection device for fluid transportation piping system. F _r > 1 + ε ………… (1) 1-ε> F _r ≧ 1-λ ………… (2) F _r <1-λ ………… (3) where ε: An error ratio determined by the characteristics of the fluid, the diameter of the pipe, the type and characteristics of the flow rate detector, etc., which is an empirically determined constant smaller than 1. λ: A ratio of the leakage amount at the limit where emergency measures are not taken even if there is a leak from the pipe to the total flow rate value on the inflow side, which is a constant larger than ε which is empirically determined and smaller than 1. 4. The abnormality detecting device for a fluid transportation piping system according to claim 3, wherein the error ratio ε is 0.2 and the leakage amount ratio λ is 0.5.