JPS5929511B2 - Storage liquid management device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid storage management device for a liquid storage tank such as an oil storage tank buried underground in a gas station or the like.

Oil storage tanks at gas stations are usually equipped with fuel gauges that measure and display the amount of stored liquid.

Since this type of oil storage tank is usually buried underground, it is necessary to monitor oil leakage and intrusion of groundwater due to perforation of the tank wall surface due to corrosion or the like. The oil level in an oil storage tank fluctuates when oil leaks or underground water intrudes, but oil level fluctuations also occur due to oil volume changes due to oil injection and pumping, and changes in oil temperature. Therefore, the oil storage management device must be able to accurately identify changes in oil level caused by these different causes. By the way, there are various types of fuel gauges,
There is a method that detects the depth of the stored liquid (height of the liquid level) as the pressure of the stored liquid.

If the oil storage tank has a shape in which the cross-sectional area does not change with height (depth), for example a cubic or vertically cylindrical type, a pressure detection type fuel gauge will detect the amount of stored liquid depending on changes in liquid temperature. Even if the volume expands, the density decreases and no change in pressure occurs, so it can be distinguished from changes in pressure (liquid level) due to leakage, etc.

However, in an oil storage tank whose cross-sectional area changes with height, when the volume changes due to changes in the temperature of the storage liquid, the pressure also changes. Therefore, in order to distinguish this case from changes due to leakage, etc., it is necessary to detect the temperature change in the stored liquid and correct the output of the pressure sensor. A circuit for performing calculations is required. However, in the case of a horizontal cylindrical liquid storage tank, the area of the horizontal plane parallel to the axis changes depending on the height of the horizontal plane, so strictly speaking, the amount of liquid stored is determined by the storage depth (height of the liquid level). However, in a certain height (depth) range, it can be considered to change linearly in practice. Now, Figure 1a,
The oil storage amount V1 of the horizontal cylindrical oil storage tank (tank 1) shown in b is given by the following equation, where the oil storage radius a, the oil storage depth hh, the tank length c, and x=a-re1.

Next, as shown in Figure 1c, consider a rectangular parallelepiped oil storage tank (tank 2) whose maximum depth is 2k smaller than the maximum depth 2a of tank 1, and assume that its oil storage volume is V2 and the maximum oil storage volume is 2max. ,2
= Vl, 2max = V, max (maximum oil storage amount in tank 1).

The liquid level height H of both tanks when the storage volumes of tanks 1 and 2 are equal,
The difference k between and H2 is k=h1-H2-k, and a=500
W! I,c=3000rft7! When L,k=100mm, V1=V2 is 1001 between 1001 and 23001
If you calculate the value of k for each case, the result will be as shown in the following table.As shown in the table above, a horizontal cylindrical liquid storage tank (tank 1) with a capacity of 23001 is installed, and its storage volume V1 is from 6001 to 1700.
In the range of 2, the change in the liquid level height is almost the same as the change in the liquid level height in the same range of 6001 to 17002 of the storage volume V2 of the rectangular parallelepiped tank (tank 2).

This is shown more clearly in the graph of FIG.

In Figure 2, the horizontal axis represents the amount of stored liquid (l), and the vertical axis represents H,,h.
2, but the graph of V is ・600 to 1700 (1)
It becomes a straight line like the graph of V2, that is, tank 1
Similarly to tank 2, it can be practically considered that within the range of the above-mentioned storage amount, the storage amount changes linearly with the height of the liquid level (liquid storage depth). The present invention has been proposed based on the above facts, and in a horizontal cylindrical liquid storage tank, within the above-mentioned linear variation range, liquid is pumped out from the liquid storage tank and transferred to the liquid storage tank. This system is designed to notify changes in the liquid level due to reasons other than liquid injection as abnormal changes due to liquid leakage or intrusion. Pressure detection detects the amount of liquid stored in the liquid storage tank as pressure and generates a corresponding signal. an alarm that performs an alarm operation in response to a change in the output of the pressure detector; and a detection means that generates a signal by detecting the injection of liquid into the liquid storage tank or the pumping out of the liquid storage tank. , a setting means for setting a predetermined range of the amount of liquid stored in the liquid storage tank to an intermediate portion of the liquid storage tank excluding both upper and lower end portions, and a signal from the pressure detector and a setting range of the setting means; comparing means for comparing the signals and generating a signal when said signal is outside the latter range; and inhibiting input of the signal from said pressure detector to said alarm in response to the signal from said sensing means or said comparing means. It is characterized by consisting of means.

The illustrated embodiment will be described below. In FIG. 3, 1 is an underground oil storage tank, and O is oil.

Reference numeral 2 denotes a fuel metering machine, in which a fuel pump 4 and other fuel supply mechanisms are installed.

The operation of the oil supply pump 4 forces oil from the pumping pipe 3 to the flow meter 5 via the oil supply path 6? Then, oil is supplied from the flow meter 5 to the equipment to be lubricated from the oil supply nozzle 9 via the oil supply hose 8.

A display 7 receives the output from the flowmeter 5 and displays the amount of oil supplied.

10 is a storage case for the refueling nozzle 9, and 11 is a nozzle detection switch, which generates a nozzle signal S1 when the nozzle 9 is removed from the case 10.

Reference numeral 12 indicates a ventilation pipe, and reference numeral 13 indicates an oil supply pipe, through which oil is supplied to the oil storage tank 1 from a tank truck (not shown) or the like.

14 is a coupling, and 15 is a lubrication signal S2 when the lubrication hose from the tank truck is connected to the coupling 14 during lubrication.
This is a coupling detection switch that generates

Signals Sl and S2 from the nozzle detection switch 11} and the coupling detection switch 15 are sent to the control unit CB in the office 16 via lead wires Ll and L2.

Reference numeral 17 denotes an air purge type pressure detector, and the creed S3 appearing on the detection section 18 is sent to the control section CB via a lead wire L3.

23 is an oil storage amount indicator O. The air purge type pressure detector 17 is supplied from a compressed air source (not shown) via a valve 19 as is well known. Compressed air is released from the lower end of the supply pipe 20 inserted into the oil 0 in the tank 1, enters the outer pipe 21 concentric with the supply pipe 20, and expels the oil in the outer pipe 21.

The pressure required to completely expel the oil in this pipe has a magnitude corresponding to the oil level height (oil storage depth) of oil 0 in the oil storage tank 1. This pressure is sent to the pressure detection section 18 and converted into a corresponding electrical signal S3. When the oil level height (oil storage amount) changes due to oil being put in and taken out of the tank, the pressure inside the outer tube 21 also changes, and the signal S3 also changes. FIG. 4 is a block diagram showing the configuration of the control section, and the output (signal S3) is given to the signal processing circuit 22.

This circuit 22 takes into consideration the specific gravity of the oil, calculates and converts the signal S3 into an oil storage amount, and provides an oil storage amount signal S4 to the oil storage amount display 23. The signal S3 is sent to the alarm 2 via the switch circuit 24.
5 is also given.

The annunciator 25 notifies the user with light or sound when there is a change in the signal S3. The signal S3 also changes when oil is pumped out from the oil storage tank 1 or when oil is added to the oil storage tank, but in this case, it is inconvenient for the alarm 25 to operate, so it is generated when the nozzle is removed from the case. Nozzle detection switch 1
1 or the signal S2 from the coupling detection switch 15 which is generated when the oil supply hose of the tank truck is connected to the coupling 14 of the oil supply pipe 13, the switch circuit 24 is opened and the signal from the pressure detection part 18 is detected. S3
is prevented from being input to the alarm 25. Signal S3 is also applied to comparison circuit 26.

The linear change range setting circuit 27 sets the range of the signal S3 from the pressure detection section 18 corresponding to the linear change range shown in the graph of FIG. The comparison circuit 26 compares the set range with the signal S3, and when the latter signal deviates from the former range, the comparison circuit 26 provides an output to the switch circuit 24 to open this circuit 24 and turn off the signal S3. Block input to 25. In other words, as long as the signal S3 is within the above-mentioned direct variation range, the signal S3 is applied to the annunciator 25 and the signal S3 is changed according to the variation of the signal S3 (excluding the case of variation due to oil filling or pumping).
The alarm 25 is operated, but if the signal S3 is outside the linear variation range, the alarm 25 is not operated.

According to this configuration, in the above example, if the oil storage amount is less than 6,000 ml or more than 17,000 ml, it will not be possible to detect oil leaks or intrusion of ground water, etc., but normally in this type of oil storage tank, the oil storage amount is within the above range. In most cases, there is no problem in practical use.

Although the embodiments have been described above, it goes without saying that the present invention is not limited thereto. For example, the output of the signal processing circuit 22 may be applied to the comparison circuit 26 instead of the signal S3. The specific configuration of the alarm 25 does not matter. The pressure detector 17 is not limited to the air purge type, and a liquid pressure detector may be provided at the bottom of the liquid storage tank, for example. As described above, according to the present invention, in a device that manages the amount of stored liquid by detecting pressure changes in the liquid stored in a horizontal cylindrical liquid storage tank, the amount of stored liquid can be kept within a certain range.
With a simple circuit configuration, there is no need to use complex calculations to correct changes in the amount of stored liquid due to changes in the temperature of the stored liquid, and the amount of stored liquid can be reduced due to leakage of liquid from the storage tank, intrusion of groundwater, etc. Changes can be known practically and accurately.

[Brief explanation of the drawing]

Figure 1a is a sectional view perpendicular to the axis of the horizontal cylindrical liquid storage tank;
Figure b is a vertical cross-sectional view including the axis of the same tank, Figure 1 c is a cross-sectional view similar to Figure 1 a of a horizontal rectangular parallelepiped liquid storage tank, and Figure 2 is a storage tank of two tanks shown in Figure 1. Graph showing the relationship between depth and liquid storage volume,
FIG. 3 is a schematic configuration diagram of an oil supply system incorporating an embodiment of the present invention, and FIG. 4 is a block diagram of an embodiment of the present invention. 1...Oil storage tank, 2...Refueling meter, 1
1...Nozzle detection switch, 15...
Coupling detection switch, 16...office, C
B...Control unit, 17...Air purge type pressure detector, 18...Pressure detection unit, 20...
... Compressed air supply pipe, 21 ... Outer pipe, 22.
... Signal processing circuit, 23 ... Oil storage amount indicator, 24 ... Switch circuit, 25 ...
Alarm device, 26... Comparison circuit, 27...
Linear change range setting circuit.

Claims (1)

[Claims] 1. A pressure detector that detects the amount of liquid stored in a horizontal cylindrical liquid storage tank as pressure and generates a corresponding signal, and an alarm that operates to notify in response to a change in the output of this pressure detector. a detection means for detecting injection into or pumping out of the liquid from the liquid storage tank and generating a signal; a setting means for setting at an intermediate portion excluding both end portions; a comparison means for comparing a signal from the pressure detector with a setting range of the setting means and generating a signal when the former signal is outside the latter range; A storage liquid management device comprising: means for blocking a signal from the pressure detector from being input to the alarm in response to a signal from the pressure detector or the comparison means.