JP3240577B2 - Tank oil leak monitoring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting oil leakage from a large oil storage tank of a floating roof type.

[0002]

2. Description of the Related Art Conventionally, there has been an oil leakage monitoring device of a type for monitoring fluctuations of a stationary oil level in a tank. This apparatus reads the value of the liquid level at the time when the oil supply / reception to the tank is completed, and uses this point as the starting point of the liquid level monitoring. Until the next shipment / shipment is performed, if a liquid level fluctuation exceeding a certain width is detected, it is determined that oil has leaked or leaked, and an alarm is issued.

[0003] In this case, if the tank is of a floating roof type, the floating roof moves when the wind blows. Therefore, the liquid level sensor linked to the floating roof detects that the liquid level does not fluctuate. Had the drawback of doing it.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to realize a highly reliable oil leakage monitoring device for a tank which does not erroneously detect the above-mentioned swinging of a floating roof due to wind pressure.

[0005]

SUMMARY OF THE INVENTION In a floating roof type oil storage tank having an inlet valve and an outlet valve, a liquid level signal from a liquid level sensor for detecting the movement of a floating roof moving in conjunction with a liquid level is provided. A wind speed signal from a wind speed sensor attached near the tank roof and an opening / closing signal of an inlet / outlet valve, and increasing the width of the liquid level fluctuation detection dead zone as the wind speed signal increases, thereby increasing the width of the inlet / outlet valve. When the is closed, it is possible to prevent that the liquid level has fluctuated due to the wind speed from being erroneously reported as oil leakage or leakage.

[0006]

According to the present invention, the inlet valve opens while receiving oil into the tank, and the outlet valve opens while sending oil. Each valve transmits its open / close signal. While the above two valves are closed, the oil leak detection operation is enabled.

[0007] The floating roof of the oil storage tank moves up and down in conjunction with the level of the stored oil. The liquid level sensor detects the oil level by detecting the vertical movement of the floating roof.
A wind speed sensor provided near the tank roof detects the instantaneous wind speed. The oil leak monitoring device selects a dead zone for liquid level fluctuation detection based on the average wind speed calculated from the instantaneous wind speed signal,
When the liquid level signal input from the liquid level sensor exceeds the dead zone, the oil leak is correctly detected, and a notification is made through a CRT or the like.

When the average wind speed signal is transmitted from the wind speed sensor, it is not necessary to perform the above calculation twice.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a configuration diagram of an apparatus showing an embodiment of the present invention. 11
Is a floating roof oil storage tank. Reference numeral 12 denotes a floating roof that moves in conjunction with the liquid level in the tank.

Reference numeral 13 denotes a tank inlet valve which generates a valve opening / closing signal c. Reference numeral 14 denotes a tank outlet valve which generates a valve opening / closing signal d. Reference numeral 15 denotes a liquid level sensor. A temperature signal e is generated together with the liquid level signal a. This temperature signal e is
It is used to calculate the change in the liquid level by converting the change in oil volume at the reference temperature.

Reference numeral 16 denotes a wind speed sensor provided near the tank roof and generates an instantaneous wind speed signal b. Reference numeral 17 denotes an oil leak monitoring device according to the present invention which receives the above signal. It is composed of an electronic computer, a process input / output device and the like. Reference numeral 18 denotes a man-machine device connected to an oil leak monitoring device, which generally uses a CRT or the like. The status of the various signals and the leak warning are displayed.

Next, the operation of the apparatus configured as described above will be described. 2 and 3 are flowcharts showing the processing operation of the oil leak monitoring device of the present invention. In Step 1,
The liquid level signal a, the wind speed signal b, the inlet valve opening / closing signal c, the outlet valve opening / closing signal d, and, if necessary, the temperature signal e are also read into the oil leak monitoring device at regular intervals [t seconds]. e is also used to monitor fluctuations in oil storage.

In step 2, an average wind speed Dbn is calculated from the instantaneous wind speed signal b. The m instantaneous wind speeds Dbnx are read and averaged to obtain the average wind speed Dbn. In step 3, a dead zone Hbn for the average wind speed Dbn is selected from a dead zone table that has been separately stored. Various average wind speed values Db1, Db2, Db3. . . The dead zone values Hb1, Hb2, Hb3. . . Is determined in advance based on experiments and experiences. FIG. 4 shows an example.

In step 4, a dead zone value Hn to be set in the oil leak monitoring device is obtained. Hn = Hd + Hbn Hd is a unique dead zone value determined for each tank. Hbn is the average wind speed Dbn in the dead zone table shown in FIG.
Is the dead zone Hbn value with respect to.

In step 5, it is confirmed that the receipt / shipment of the oil is completed due to the input of the closing signals from all the valves, and that the fluctuation of the liquid level is not based on the receipt / shipment of the oil. The leak monitoring is started from this point. In step 6, after the receipt and shipment of the oil is completed, it is confirmed that the monitoring of the liquid level in the tank is the first time, and the process proceeds to step 7. If the number of times of monitoring is the second or later, the process proceeds to step S8.

In step 7, if the value of the liquid level in the tank which is read first after the oil shipment / shipment is completed is M, the value is set as the monitoring reference liquid level. In step 8, the liquid levels Da1, Da2, Da3. . . Is (M-
Hn) is checked, and if there is a liquid level higher than this value, it is considered that there is no oil leakage, and the flow proceeds to step 9;
Proceed to.

It is checked whether the liquid level is equal to or less than (M + Hn). If there is a liquid level lower than this value, it is determined that there is no oil leakage. The process proceeds to step 10 assuming that the load has occurred. In step 9, the alarm occurrence flag detected at the time of the previous monitoring as the absence of leakage is reset.

In step 10, it is checked whether a leak was detected during the previous monitoring. In step 11, the alarm generation flag is reset once so that the leakage alarm does not continue to be output. In step 12, when an oil leak is detected, a leak alarm is displayed on the above-described CRT or the like.

The change in the oil level and the change in the dead zone at the time of an alarm will be described with reference to FIG. (1) In a non-monitoring state before time To, it indicates that the inlet valve is opened to receive oil, and the liquid level in the tank is rising. The opening / closing of the outlet valve, the wind speed, and the width of the dead zone do not matter in this case. The figure shows the wind speed Dbn zero. (2) In the monitoring state after time To, there is no oil flowing into and out of the tank, and it is confirmed that both of the inlet valve and the outlet valve are receiving a close signal. In a windless state, the liquid level in the tank does not fluctuate, and thus the width of the dead zone does not fluctuate due to Hd unique to the tank.

(3) When the wind speed Dbn is generated, the width of the dead zone with respect to the average wind speed is selected according to the magnitude as shown in FIG. The width of the detection dead zone of the leak monitoring device is increased each time the times T1 and T2 and the average wind speed exceed a certain value. For example, the wind speed Db2 between times T2 and T3
On the other hand, Hb2 is selected as the dead zone from FIG. 4, and the dead zone Hn in which the monitoring device operates is Hd + Hb2. Until the liquid level drops from the reference value M beyond M-Hn, it is not detected that oil has leaked. If the dead zone in which the device operates is kept at Hd, when the fluctuation of the liquid level appears as in a, an alarm is issued assuming that the oil has leaked. (4) If the liquid level still drops even when the wind speed drops, it is considered that there is a leak in the tank and an alarm is issued. This is the case of b in the figure. In this way, false alarms due to wind-induced swaying of the floating roof are prevented.

The width of the dead zone has a tendency peculiar to the influence of the wind direction and the wind speed on each tank, and is represented by Hd.
It is obtained and used in advance based on experience and experiments together with Hbn.

[0022]

According to the present invention, the width of the dead zone for detecting the liquid level of the oil tank is increased when the wind speed is high and the floating roof is largely shaken. This has the effect of reducing false reports.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention.

FIG. 2 is a processing flowchart of a part for obtaining a value of a dead zone.

FIG. 3 is a processing flowchart of a part that performs monitoring and warning.

FIG. 4 shows an example of a dead zone value corresponding to an average wind speed.

FIG. 5 is a diagram illustrating a change in oil level due to a wind speed and a change in a dead zone at the time of an alarm.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Floating roof type oil storage tank 12 Floating roof which moves in conjunction with the liquid level of tank 13 Inlet valve of tank 14 Outlet valve of tank 15 Liquid level sensor 16 Wind speed sensor provided near tank roof 17 Oil leak monitoring device 18 CRT device connected to oil leak monitoring device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-68286 (JP, A) JP-A-64-70395 (JP, A) JP-A-1-1111691 (JP, A) JP-A-55-1985 107675 (JP, A) JP-A-59-119410 (JP, A) JP-A-61-27892 (JP, U) JP-A-4-84999 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B65D 88/00-90/66 G08B 21/00 G05D 9/12 G05B 23/02 302

Claims (1)

(57) [Claims] 1. A liquid level signal from a liquid level sensor for detecting up and down movement of a floating roof which moves in conjunction with a liquid level of oil to detect oil leakage from a floating roof type oil storage tank. The wind speed signal from the wind speed sensor attached near the tank roof and the open / close signal of the inlet / outlet valve of the tank are input, and the liquid level signal input after the oil is loaded / shipped into the tank is set as the reference liquid level.
An oil leakage monitoring device characterized in that the width of a detection dead zone for liquid level fluctuation is increased as the wind speed signal increases, and oil leakage is detected based on the amount of fluctuation from a reference liquid level.