JPH02176440A - Monitoring method for pipe - Google Patents

Abstract

PURPOSE:To confirm leakage from a piping system accurately by decreasing the pressure of fluid in a divided pipe which is separated with values lower than the pressure on the upstream side from an upstream-side valve, confirming the presence or absence of the leakage from the upstream-side valve, thereafter filling the divided pipe with the fluid again, closing all valves, and judging the presence or absence of the leakage. CONSTITUTION:When a pump 31 is started and fuel is supplied into a burning furnace 9 from a tank 1, valve from front and rear valves 16 and 17 to begin with upto a shutoff valve 8 in one system are all opened. At this time, oil leakage between the valves 17 and 8 is confirmed as follows. At first, each valve is opened, and a pipe 5 is filled with the oil. Then, the valves 17 and 8 are closed, and a divided section is formed. Thereafter, valves 12 and 27 which are communicated to a low pressure system are opened, and the pressure in the divided section is decreased to a specified value. Then the valves 12 and 27 are closed. When the pressure in the pipe 5 between the valves 17 and 8 is not increased, it is confirmed that there is no leakage in the valve 17. Then, the valve 17 is opened, and the pipe is filled with the oil. All valves are closed again, and the decrease in pressure in the pipe 5 is confirmed. In this way, the presence or absence of the leakage between the valves can be confirmed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for monitoring piping systems in various plants, and in particular to a method for detecting pressure changes within a range closed between valves in a piping system. The present invention relates to a method for monitoring leakage in a system including piping and valves, and a method for monitoring excessive pressure rise in the above range.

[Conventional technology]

In conventional piping systems, many of the valve structures used were manual valves, and there was no proper leakage monitoring device. If the fluid in the pipe is fuel oil such as crude oil or heavy oil, there is a high risk of leakage, so 'liA'/! There is a growing need to develop and use i-detection devices.

In addition, for large boilers, to check for leaks in the fuel system piping and valves, after filling the piping to the burner with oil at startup or when the system begins to use, fully close the valve and hold it for a certain period of time. Some systems employ a method in which it is determined that there is no leakage if the pressure drop width between them is within a certain value.

That is, in FIG. 4, a large number of burners 10 are arranged in a combustion furnace 9 of a boiler, and a pipe that supplies fuel to the burners 10 has a shutoff valve 8 at its inlet and a burner circulation valve 25 at its outlet. The leakage check performed in this fuel pipe is to close the valve 25, then open the valve 8, supply fuel into the pipe, and then close the valve 8. In other words, the fluid fuel is contained at a constant pressure, and the leakage check is performed at a constant pressure. It was determined that there was a leak if the pressure decreased by more than a certain value within a certain period of time. However, in the above leakage check, the leakage check of the shutoff valve 8 itself is not performed, and if there is a leakage in the shutoff valve 8, even if there is a leakage in the piping section on the downstream side or the circulation valve 25, there will be a leakage check in the piping. No pressure drop occurred, resulting in an erroneous determination that there was no leak.

On the other hand, steam traces, heating cables, and the like have been used as heating devices to prevent the fluid in piping from freezing or coagulating. In such a piping system, there are inconveniences such as the pressure rising due to the heating of the area closed off by the valves and exceeding the design pressure of the piping system, so it is necessary to install a pressure relief system and monitor and control the heating upper limit. It was handled by

[Problem to be solved by the invention]

Since the above-mentioned conventional technology captures pressure changes within a range closed off by valves in the piping system, the above-mentioned erroneous judgments may occur, and the influence of temperature on the fluid pressure in the piping is not taken into account. When a fluid is filled in a low-temperature pipe, the pressure drops due to the difference between the fluid temperature and the pipe temperature, making it impossible to accurately distinguish between a leak and a leak. Temperature changes cannot be ignored depending on the type of fluid, and are particularly problematic when the fluid is dangerous. Further, when the fluid is a gas (eg, gas fuel), the change in specific volume is large especially with respect to temperature change, so this measure is necessary.

A first object of the present invention is to perform accurate leakage monitoring within a piping system.

Next, the above-mentioned conventional technology does not take into consideration the fact that a complete shutoff range is created by the valves in the piping system, and there are problems such as heating and pressure rising above the design pressure. For a very short period of time, the proof stress of the piping will be 11% of the design pressure.
In some cases, up to 6% is allowed, but there are problems such as damage to instruments installed in the piping system. Additionally, even if a piping system is equipped with a pressure relief valve, depending on the type of fluid, it may be expensive or dangerous, and there is a desire to minimize the chances of the relief valve being activated. is strong.

A second object of the present invention is to eliminate abnormal pressure increases in the piping system when the valves are shut off.

[Means for Solving the Problems] The problem of the above-mentioned conventional technology is to monitor leakage in a piping path separated by an upstream valve provided in a piping path that causes fluid to flow from an upstream side to a downstream side. In this method, after closing the upstream and downstream valves with the pipe filled with fluid, the difference between the pressure in the divided pipe and the fluid pressure on the upstream side of the upstream valve is determined, and the desired pressure difference is obtained. If the pressure difference has not been reached, open the valves below the above-mentioned upstream valve that communicate with the outside in the pipe, discharge the fluid in the pipe to the outside to reach the desired pressure difference, then close the discharge valve to reduce the desired pressure. If the difference has been reached, measure the pressure inside the divided pipes without discharging the fluid inside the pipes to the outside, and check whether the pressure change within the specified time is within the specified value. Accordingly, the problem is solved by a pipe line monitoring method characterized by determining the presence or absence of leakage from the above-mentioned upstream valve.

[Effect]

Piping systems are constructed so that fluid always flows through them. Therefore, if a certain range is closed off by valves depending on the operating conditions, it can be considered that the system has been divided by at least two valves, and judging from the operating state of the system, one of the It is possible to open one valve. If one valve is opened to a specified opening degree to reduce the pressure within the shutoff range and then fully closed, it can be seen that there is no leakage in the high pressure side valve due to pressure changes within the shutoff range. Therefore, the high-pressure side valve is opened, filled with fluid, and then fully closed again to determine whether there is a leak based on the pressure change.

This is sequentially operated for each valve that separates the system to determine leakage in the entire system. In this case, the effect of fluid temperature changes on pressure is corrected.

On the other hand, in a piping system that is divided into two or more valves, it is possible to open any one of the 11 [1 valves], judging from the operating state of the system, and one valve can be opened to a specified opening degree. As a result, there is no cut-off range, so there is no increase in pressure due to heating.

〔Example〕

FIG. 2 is a piping system diagram showing the first embodiment of the present invention. Fuel is pressurized from the fuel tank 1 by pumps 31 and 32, heated by heaters 41 and 42, and then supplied to burner 10 of combustion furnace 9 through pipe 5. On the other hand, the fuel from the fuel tank 2 is pressurized by the pumps 33 and 34 and merged into the pipe 5. It is supplied to the burner 10 via a supply flow meter 6, a flow rate adjustment valve 7, and a cutoff valve 8. The pressure in the pipe 5 is controlled to be constant by a pressure regulating valve 12 based on the pressure detected by a pressure controller 11. The return flow rate is measured by a return flow meter 13, and by subtracting the measured value of the return flow meter 13 from the supply flow meter 6, the fuel consumption amount of the burner 10 is determined.

Now, if we start the pump 31 and start filling it with oil, each valve will fully open at least one system from the front and rear valves 16 and 17 of the pump 31 to the shutoff valve 8 to supply oil. However, it is necessary to check for leaks between valves 17 and 8. If the valve 17 is fully closed and the pressure change in the pipe 5 is measured, determination can be made by determining the pressure drop within a certain period of time. At the same time as pressure changes, temperature changes are measured to compensate for changes in volume.

A leak check in the area between valves 17 and 8 begins with valves 18, 19, 20, 21, 23, 7 from valves 17 to 8.
．． 24 is opened and the pipe line 5 is filled with fluid. Then valve 17
and 8 to form divided areas. Afterwards,
Valves 12 and 27 leading to the low pressure system are opened and after the pressure in the area has been reduced to a predetermined value, valve 12.27 is closed.

Next, if there is no increase in the pressure in the pipe 5 between the valves 17 and 8, it can be confirmed that there is no leakage in the valve 17. Therefore, the valve 17 is opened, filled with fluid, and completely closed again to check whether the pressure inside the pipe 5 has decreased. If there is no decrease after a certain period of time, it is determined that there is no leakage.

When checking pressure changes, corrections based on fluid temperature are of course performed. Note that the pressure in the pipe between the valves 17 and 8 can also be lowered by opening the valve 8 a little. Here, if the pressure drop is large (and it is determined that there is a leak), for example, by sequentially checking between valves 17 and 19, between valves 19 and 20, between valves 20 and 23, and between valves 23 and 8. , leak points in piping systems can be identified.

FIG. 1 shows a block diagram of the leakage confirmation operation.

Judgment results are displayed based on the combination of conditions. pump 3
After filling the pipe with fluid at a predetermined pressure by 1, the valve 17
and 8 fully closed. At this time, the valves of the circuits branching from this piping system are closed.

Next, the measured value of the fluid temperature in the pipe is multiplied by the volume coefficient, which is the rate at which the volume changes due to temperature, and the actual pressure is corrected to obtain the true pressure in the pipe 5. If the pressure is above the specified pressure value, it is determined that there is no leakage, and if not, a leakage determination display is displayed on the piping between valves 17 and 8, and a display indicating that the leakage location identification circuit is operating is displayed to locate the leakage location. Perform operations to identify. That is,
The same operation as above is carried out between valves 17 and 19.

Regardless of whether there is a leak between valves 17 and 19, a leak check operation is performed between valves 19, 20, 20, 23, and 23 and 8. This means that even if it is confirmed that there is a leak between valves 17 and 19, there is a leak between valves 17 and 8.
The cause is not necessarily due to leakage between valve 19 and valve 19.
This is because it cannot be said that there is no leakage between

Next, a second embodiment of the present invention will be described.

In the piping system shown in Fig. 2, if oil that solidifies easily is used as fuel oil, the steam trace piping 14 should be divided into several sections for all of the above piping and equipment, and the steam trace piping 14 should be divided into several sections. Heat it through. The heating temperature by steam tracing is determined by the set value of the thermotrap 15.

If the pump 32 is currently in use and the pump 31 is stopped and both the front stop valve 16 and the rear stop valve 17 are fully closed, the pressure in the piping will increase due to heating by the steam trace 14. Therefore, it can be seen that it is better to keep the front stop valve 16 fully open. Similarly, various combinations of valves 18 and 19, valves 20 and 21, valves 20, 22 and 23, valves 23 and 8, 24 and 23, valves 20, 22 and 8, etc., can be considered to achieve a complete shut-off state. If necessary, we will notify the operator through an alarm or guide display.

In addition, information indicating the opening/closing status of the valve and the operating status of the pump is transmitted to a control panel with arithmetic functions such as an electronic computer.
Determine and monitor whether any valves in the piping system are closed, and if there are any areas that are closed, check whether the area is safe as determined from the operating status of the entire piping system. Open side valves to demarcate areas within the piping system with relief valves or modify valve operation to provide pressure communication with the operating piping system.

In addition, as one example of this embodiment, the operation does not occur only when the shut-off state occurs, but when the shut-off state continues and the pressure in the shut-off pipe exceeds the set value, the It is also effective to open one valve.

FIG. 3 shows the above embodiment as an abnormality determination block diagram. Guide items are displayed depending on the combination of conditions.

In addition, in the first embodiment described above, if there is a leak from valves 17 to 8 in the system shown in FIG.
It is also possible to narrow the range from 17 to 23, then from valve 17 to 201, and from 17 to 19 to identify the leakage location, which is within the scope of the idea of the present invention.

〔Effect of the invention〕

According to the present invention, it is possible to accurately check for leaks in a piping system, and reliability can be improved. Furthermore, even if the piping is heated to prevent freezing or solidification of the piping system, it is now possible to maintain the pressure in the piping within the design value.

[Brief explanation of the drawing]

FIG. 1 is a block diagram illustrating the leakage monitoring method for piping according to the present invention, FIG. 2 is a fuel oil piping system diagram applicable to the present invention, and FIG. 3 is a second embodiment of the present invention. Block diagram of method for preventing pressure rise in piping for explaining examples, 4th vI
! J is an explanatory diagram of the prior art. 1.2... Fuel oil tank, 5... Piping path, 6...
Supply flow meter, 7...Flow rate adjustment valve, 8...Shutoff valve, 9
... Combustion furnace, lO ... Burner, 11 ... Pressure controller, 12 ... Pressure adjustment valve, 13 ... Return flow rate needle, 16 ... Pump inlet valve, 17 ... Pump outlet valve , 18... Heater population valve, 19... Heater outlet valve,
20...Flowmeter inlet valve, 21...Flowmeter outlet valve, 2
2...Flow rate needle bypass valve, 23...Flow rate adjustment valve large stop valve, 24...Flow 1mm regulating valve stop valve, 25...Burner circulation valve, 27...Tank return valve, 30... ...Oil temperature needle, 31.32.33.34...Pump, 41.42
···Heater. Applicant Babcock Hitachi Co., Ltd. Agent Patent Attorney Takeshi Kawakita Fuel oil tank (A) Fuel oil tank (B) Piping line supply flow meter flow adjustment valve Shut-off valve Combustion furnace burner pressure controller Pressure adjustment valve Return flow meter Pump inlet valve pump outlet valve heater population valve heater outlet valve flow meter inlet valve flow meter outlet valve flow meter bypass valve flow control valve inlet stop valve flow control valve outlet stop valve burner circulation valve tank return valve oil temperature liver pump heater

Claims (3)

[Claims] (1) A method for monitoring leakage in a piping line separated by an upstream valve provided in a piping line that causes fluid to flow from an upstream side to a downstream side, and a downstream side, in which the piping line is filled with fluid. After closing the upstream and downstream valves in this state, calculate the difference between the pressure in the divided pipe and the fluid pressure on the upstream side of the upstream valve, and if the desired pressure difference has not been reached, check whether the pipe is connected to the outside. Open the valves below the above upstream valve and discharge the fluid in the pipeline to the outside to reach the desired pressure difference, then close the discharge valve, and if the desired pressure difference has been reached, the fluid in the pipeline is discharged to the outside. The pressure inside the separated piping is measured without being discharged, and the presence or absence of leakage from the upstream valve is determined based on whether the pressure change within a predetermined time is within a specified value. A characteristic method for monitoring piping. (2) A method for monitoring piping according to claim (1), characterized in that when measuring the pressure and pressure difference, pressure is corrected based on the fluid temperature at the measurement location. (3) A method for monitoring a piping path that has a plurality of valves that open and close the fluid flow path, and a heating device that heats the fluid in the flow path to flow the fluid from the upstream side to the downstream side,
A step of detecting and registering the opening/closing status of the valve, a step of determining whether or not the piping path is closed by the upstream valve and the downstream valve to form a sealed path based on the registration result, and a step of sealing as a result of the above judgment. With respect to the piping path forming the pipe path, the piping path is characterized by comprising the step of opening at least one valve of the valves provided in the piping path to prevent an abnormal pressure increase in the piping path. monitoring method.