JPH045125B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for measuring uneven settlement of a tank for storing liquid or the like.

When attempting to store liquids such as crude oil or heavy oil on land, the amount of storage required is extremely large, so a huge tank is required. Some of the largest tanks have a diameter of about 100 meters, a height of about 20 meters, and a capacity of up to 150,000 tons of water. These tanks are often installed near the relevant Shanghai beaches where crude oil is transported by tanker (ship). Furthermore, the ground on these beaches is often soft due to land reclamation and development. If a huge tank is installed on such ground, the ground 1
The load is approximately 20 tons per m ² , which tends to cause ground subsidence. If this sinking is uniform throughout the bottom of a tank with a wide bottom area, there will be no problem, but uneven settling may occur. When this uneven settling occurs, stress is applied to the tank structure, causing deformation and cracking not only at the bottom of the tank but also at the sides and top, which becomes a major cause of leakage of tank contents. If this leakage is large, it will contaminate a very wide area in the area where the tank is installed, and especially if the contents of the tank are flammable or hazardous, it will cause extremely serious social problems and pollution as it can be life-threatening. It can also be a problem. In order to prevent such a situation from occurring, various methods and devices for measuring the uneven settlement of various tanks have been proposed.

Conventionally, one method of measuring this uneven settlement is to
A method has been used to measure the subsidence from a reference point (benchmark) at a predetermined location on the outer periphery of a tank using a leveling device used as a surveying instrument for civil engineering, construction, etc. This measurement requires a lot of effort and time (usually about a day). However, the uneven settlement of the tank is so variable that it is said that it is photographed even during the ebb and flow of the tide. Therefore, measurements at levels that cannot be measured within a short period of time are not suitable for measuring uneven subsidence.

In addition, there are other measurement methods that apply Pascal's principle. An example of this is shown in Figures 1 and 2.
Shown in Figures AC. In FIG. 1, 1 is a liquid storage tank, and on its peripheral wall 2 are water tanks t0, t1.
...tn and te are installed, and each water tank t0, t1
... tn and te are communicated through a communication pipe 3. The water tanks t0, t1...tn, te and the communication pipe 3 descend together with the peripheral wall 2 of the tank 1 as the tank 1 sinks. The water tank t0 is used as a reference tank, and in order to maintain a constant liquid level in this reference tank, a drain port 4 is provided at the top of the water tank t0 as shown in Fig. 2, and water W is always allowed to flow only into the water tank t0. . Figure 2A shows a reference water tank t0 and a water tank tn (1=≦n≦e), and 5 is an expansion/contraction adjustment section that does not affect the vertical movement of the water tanks t0, t1,...tn, te. It is. Second
Figure B shows the state when the water tank tn is submerged relative to the reference water tank t0. At this time, water W is constantly injected into the water tank t0 and overflows from the drain port 4, so the water depth h0 is constant. Therefore, the sinking distance ln of the water tank tn (based on the water tank t0) is determined as ln=hn-h0 (1). Conventionally, as a means of measuring the amount of water depth variation hn in each water tank tl to te, a connecting rod 7 having a core is connected to the upper part of a float 6 as shown in FIG. There is a system in which the differential transformer is configured to enter and exit the differential transformer, and the output signal of this differential transformer is appropriately processed to determine the amount of water depth variation hn. According to this latter conventional method, measurement can be carried out automatically and within a short period of time, but on the other hand, the following problems arise. That is, it is extremely uneconomical to constantly replenish water W due to the effects of changes in the water surface due to tension, compression, expansion, etc. of the communication pipe 3, changes in water volume due to water evaporation, and sinking of the reference water tank t0. As a result, there was a problem in that air may get mixed into the communication pipe 3, especially in the expansion/contraction adjustment part 5, resulting in a pressure difference and the height of the water surface becoming uneven. Furthermore, if automatic measuring means such as the above-mentioned differential transformer is not provided, each water tank t1 to
It was very time-consuming because the water level had to be read.

The present invention has been made in view of the above-mentioned problems, and is a method for measuring uneven settlement of a tank, which can easily and quickly measure uneven settlement of a tank, has high measurement accuracy, and has extremely low maintenance costs. The purpose of this invention is to provide a device for the same.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 3 is a schematic diagram showing the configuration of an embodiment of the uneven settlement measuring device for a tank according to the present invention.

In the figure, 9 is a straight cylindrical (in this example, cylindrical) reference liquid column pipe installed at a reference point to be used as a reference for sinking of the outer peripheral wall of the tank 1, and the upper end is 2
One branch pipe 9a is communicated with the atmosphere through a valve V0 serving as an atmosphere release valve, and the other branch pipe 9b is communicated with the compression chamber of the cylinder 10. T1, T2...Tn, Te
are small liquid tanks in the shape of a straight cylinder (in this example, a right cylinder) installed on the peripheral wall of the tank 1, which is the object to be measured, and the inner diameter thereof is considerably larger than the reference liquid column pipe 9. has been done. These small liquid tanks T1
The bottoms of ~Te can be communicated with a common communication pipe 11 via valves V1 to Ve, respectively, and this communication pipe 11 is also communicated with the lower end of the reference liquid column pipe 9. A piston 12 is slidably fitted into the cylinder 10, and the piston 12 is moved up and down by a servo motor M via a connecting rod 13 connected to the center thereof. . The small liquid tank Te is located near the reference liquid column pipe 9,
That is, it is installed at a location in the tank 1 that can be considered to move up and down integrally with the reference liquid column pipe 9. An inert liquid is stored inside each of the small liquid tanks T1 to Te, the reference liquid column pipe 9, and the communication pipe 11. Liquid level detection means 14 for detecting (measuring) the height of the liquid level of this inert liquid in the reference liquid column tube 9 is provided so as to face the reference liquid column tube 9. This liquid level detection means 14
Although detailed illustrations are omitted, for example, a photoelectric detection device consisting of a large number of light emitting elements and light receiving elements arranged in a line may be arranged along the reference liquid column tube 9, or Possible means include connecting a pressure gauge to the bottom of the reference liquid column tube 9, or providing a scale for measuring the length on the reference liquid column tube 9 itself (or attaching a so-called ruler).

15. Liquid level height adjustment means, for example, when the liquid level detection means 14 detects the height of the liquid level and the detected value (measured value) is higher than the reference value, the servo motor M is moved in one direction. When the detected value is lower than the reference value, the servo motor M is rotated in the other direction, and when the detected value matches the reference value, the servo motor M is stopped.

Next, an embodiment of the method for measuring uneven settlement of a tank according to the present invention will be explained using the embodiment having the above configuration with reference to FIG.

It is assumed that the tank uneven settlement measuring device is installed in the tank 1, which is the object to be measured, as described above.

(1) At the beginning of measurement, all valves V0, V
1, V2...Open Ve. Each small liquid tank T1~
Since Te and the reference liquid column pipe 9 are connected through the communication pipe 11, the liquid levels of the inert liquid are all at the same height.

(2) In the above state, measure (detect) and record the value of the liquid level height or liquid column pressure in the reference liquid column tube 9 (or store the output signal of the liquid level height detection means 14 in the memory). (The same applies hereafter). The measured value here is defined as the reference value m0.

(3) Immediately after completing the above measurement, valve V1~
Close everything on Ve.

(4) At the time of the next measurement after an appropriate amount of time has elapsed, prior to the measurement, the valve Ve of the small liquid tank Te and the valve V0 of the branch pipe 9a placed near the reference point are
is opened, and the height of the liquid level in the reference liquid column tube 9 or information corresponding to this height is measured or recorded. At this time, if the liquid level in the reference liquid column pipe 9 is not the same as the liquid level at the initial stage of measurement, that is, if the measured value m is not the same as the reference value m0, the upper liquid level height adjusting means closes the valve V0. After adjusting the liquid level to be the same as the reference value while moving the piston 12 up and down by rotating the servo motor M at 15, the valve Ve is closed.
In addition, in order to adjust this liquid level, the above-mentioned liquid level height adjusting means 15, servo motor M, and piston 1 are used.
2. It is possible without using the branch pipe 9b or the like. For example, you can adjust the liquid level by draining or replenishing the liquid in the small tank Te, or you can mechanically adjust the liquid level by draining or replenishing the liquid in the small tank Te.
Adjustments may be made by moving Te up and down.

(5) Next, open the valves V1 and V0 of the small liquid tank at the location to be measured, for example, the small liquid tank T1 adjacent to the reference liquid column pipe 9, and raise the liquid level m1 of the reference liquid column pipe 9. Measure.

(6) After closing the valve V0 and adjusting the height of the liquid level in the reference liquid column pipe 9 to be equal to the reference value m0 using the liquid level height adjusting means 15 (or other means), close the valve V1. Close.

(7) Continuing, for the second, third...nth measurement points, perform the above (5) and
According to the main order described in (6), the measured values m2, m3...
…get mn.

The reference value m0 is subtracted from each of the measured values m1 to mn obtained as described above, and the amount of change H1, H2... with respect to the reference value on the reference liquid column pipe 9 is calculated for each measurement location.
Find Hn. The amount of change H1 obtained in this way
From ~Hn, the relative displacement (vertical movement) Ln of each small liquid tank with respect to the reference liquid column pipe 9 (reference location) is determined as follows.

That is, in FIG. 4, the cross-sectional area of the reference liquid column pipe 9 is A0, and the cross-sectional area of the small liquid tank Tn is An (A0<An).
Assuming that the small liquid tank Tn is displaced relative to the reference liquid column pipe 9,
Suppose that the position is lowered by Ln and the position is changed from the position of the broken line to the position of the solid line in the figure. Then, when the valve Vn of the small liquid tank Tn is opened, the liquid level in the reference liquid column pipe 9 drops (changes) by Hn, and the height of the liquid level (depth from the bottom) of the small liquid tank Tn changes from hn to hn. ′.

Between these variables, Hn・A0＝(hn′−hn)・An……(2) Because of the relationship, the relative displacement Ln of the small liquid tank Tn is Ln=Hn+(hn′−hn) ……(3) From equations (2) and (3) above, the relative displacement Ln is Ln=Hn(1+A0/An)...(4) It can be found as

This relative displacement L1...Ln is determined by each measured value m1 to m
The calculation may be performed each time n is measured, but it goes without saying that the calculation may be performed all at once after each measurement is completed.

According to the embodiment and measurement method configured as described above, the liquid level change in the reference liquid column pipe 9 is corrected immediately before measuring the uneven settlement of the tank, so that each of the small liquid tanks T1 to Te and these Evaporation or leakage of liquid stored in the communication pipe 11 etc. that communicates with
Errors caused by expansion, contraction, etc. of the liquid or communication pipe due to temperature changes can be completely eliminated, making it possible to measure uneven settlement with extremely high accuracy.

In addition, each valve V1 to Ve and V0, for example,
If it is configured with a solenoid valve and its opening/closing can be controlled remotely from the reference point, the measurer only needs to be at the reference point and measure (record) the height of the liquid level in the reference liquid column pipe 9. Because of this, the measurement efficiency is improved and all measurements can be completed in a very short time.

Furthermore, since the measurement procedure does not involve complicated means as described above, even those who are not particularly skilled can easily perform the measurement. In particular, the liquid level detection means 1
Input the output signal of 4 to the liquid level height adjustment means 15,
By attaching a control device configured to drive and control the servo motor M until the liquid level height m matches the reference value m0, and controlling the opening and closing of the valves V0, V1...Vn in a predetermined sequence, Fully automatic measurement is also possible. In addition, since the cross-sectional area A0 of the reference liquid column pipe 9 is set to be considerably smaller than the cross-sectional area An of each small liquid tank T1 to Te, the vertical fluctuation amount of each small liquid tank (tank sinking amount) On the other hand, compared to the case where both have the same cross-sectional area, the amount of liquid level change Hn in the reference liquid column pipe 9 appears larger,
The effect of improving the detection accuracy (resolution) of the liquid separation surface height can be obtained.

Note that the present invention is not limited to the embodiments described above and shown in the drawings, and various modifications can be made within the scope of the invention.

For example, when a pressure-type liquid column meter is used as a means for detecting the liquid level height, the density (or specific gravity) of the liquid forming the liquid column is greatly affected by temperature changes, and errors due to temperature changes may be introduced. Sometimes.
Therefore, it is desirable to add the following procedure to the above measurement procedure.

That is, at the stage just before each measurement, e.g.
At the stage after the measured value m is made to match the reference value m0 in the above measurement procedure 4 and the valve Ve is closed, the branch pipe 9a
Valve V0 is opened and measurement is performed with a pressure type liquid column meter, and the sensitivity of the indicator is adjusted so that the indicator of the liquid column meter indicates m.

Although water is generally used as the liquid stored in each of the small liquid tanks T1 to Te and in the reference liquid column pipe 9, it is preferable to use an inert liquid. That is, there is less corrosion, leakage, evaporation, air bubbles, etc. of the communication pipes and small liquid tanks. Incidentally, Fluorinert (USA) has been shown to be highly effective when applied to the present invention.
(registered trademark of Minnesota Mining and Manufacturing Co.) is already available on the market. This liquid is a soft liquid and is completely inert, so it does not attack small liquid tanks or communication pipes, and has a high specific gravity and strong permeability, so it has a strong force to expel air and does not cause bubbles to form in communication pipes. Therefore, no liquid level change (error) occurs due to the inclusion of air bubbles. In addition, since the viscosity is low, the difference in height between each small liquid tank is quickly transmitted, there is little loss in measurement time, and since it is non-flammable, non-toxic, and odorless, there is no danger even if it leaks. Furthermore, its freezing point is much lower than that of water, making it suitable for use even in cold regions.

Further, since the amount of evaporation is small, the amount of replenishment is smaller than that of water, but when used for a long period of time, it is desirable to form a film of a nonvolatile liquid such as silicone on the liquid surface.

As described in detail above, according to the present invention, immediately before measuring the uneven settlement of a tank, the reference liquid column pipe installed at the reference point and the small liquid tank installed at the point that can be considered as the reference point are measured. Immediately before measurement, we connect the communication pipe via a valve, and if the height of the liquid level in the reference liquid column pipe changes from the initial reference value, we correct this. It is possible to completely eliminate errors caused by evaporation of liquid stored in small liquid tanks and communication pipes connecting these, liquid leakage, expansion and contraction of liquid and communication pipes due to temperature changes, etc. , it becomes possible to perform uneven settlement with extremely high precision.

In addition, the valves of each small liquid tank and the atmosphere release valve are configured to be remotely controlled from the reference point, so the measurer can be at the reference point and check the height of the liquid level in the reference liquid column tube. Since it is only necessary to measure or record the above-mentioned liquid level, the efficiency of the measurement work including the work of correcting the liquid level is improved, and all measurements can be completed in a very short time.

Furthermore, since the cross-sectional area of the reference liquid column pipe is set to be considerably smaller (that is, thinner) than the cross-sectional area of each small liquid tank, both of them have the same cross-sectional area in response to the amount of vertical fluctuation of each small liquid tank. Compared to the case where the area is
The amount of liquid level change in the standard liquid column volume appears large,
The detection accuracy of the liquid level height can be improved, and even smaller amounts of sinking in the tank can be detected.
Very effective.

In addition, as in the invention set forth in claim 2, liquid level adjusting means comprising a cylinder, piston, etc., closes an atmosphere opening valve to correct liquid level changes in a reference liquid column pipe prior to measurement. By configuring the system so that the liquid level adjustment means can be controlled in accordance with the output of the liquid level detecting means, it is very economical because there is no need for wasteful discharge of liquid. This has made it possible to automate measurement work.

Furthermore, as in the invention set forth in claim 4, a completely inert, highly permeable, and highly permeable liquid is used as the liquid stored in each small liquid tank and the reference liquid column pipe. By using this, there is no change in liquid level due to the inclusion of air bubbles, and the difference in height between each small liquid tank is quickly transmitted to the reference liquid column pipe, making it non-flammable, non-toxic, and
Since it is odorless, there is no danger even if it leaks, and it will not damage small liquid tanks or communication pipes.

[Brief explanation of drawings]

Fig. 1 is a plan view showing an example of a conventional tank unequal settlement measuring device installed on the tank peripheral wall; Figs. 2 A, B, and C are diagrams for explaining the conventional measurement method; and Fig. 3 The figure is a schematic diagram showing the configuration of an embodiment of the present invention, and FIG. 4 is a schematic diagram for explaining the measurement principle of the present invention. 1...Tank, 9...Reference liquid column pipe, 10...Cylinder, 11...Communication pipe, 12...Piston, M
...Servo motor, 14...Liquid level height detection means,
15...Liquid level height adjustment means, V0, V1, V2...
Vn, Ve...Valve, T1~Tn, Te...Small liquid tank.

Claims (1)

[Claims] 1. A method for measuring uneven settlement of a tank, comprising:
A straight cylindrical small liquid tank with a cross-sectional area An is installed at each of a plurality of locations where the vertical movement of the tank is to be measured, and the location can be considered to be the same installation location as one of the small liquid tanks, and the above-mentioned A straight cylindrical reference liquid column pipe with a cross-sectional area A0 that is considerably smaller than the cross-sectional area of the small liquid tank is installed at a reference point that is used as a reference point for the sinking of the tank, and each of the small liquid tanks and the reference liquid column pipe are made common to each other. The reference liquid column pipe and all of the small liquid tanks are connected to each other through a communication pipe and a valve at each location, and liquid is stored inside these, and at the beginning of the measurement, all of the valves are opened by remote control to connect the reference liquid column pipe and all of the small liquid tanks. After measuring or recording the height of the liquid level in the reference liquid column pipe or information corresponding to the height of the liquid level as a reference value while communicating with the valves, all of the valves are closed. However, at the time of the next measurement after an appropriate period of time has elapsed, prior to the measurement, open the valve of the small liquid tank installed at the point that can be considered as the reference point and check the height of the liquid level in the reference liquid column tube or the liquid level. Measure or record information corresponding to the height of the surface, and if the value has changed from the reference value, correct it with the liquid level height adjustment means so that it becomes the same as the reference value, and then Close the valve of the small liquid tank, then open the valve at the point where the sinking of the tank is to be measured, and change the height of the liquid level in the reference liquid column pipe or the information corresponding to the height of the liquid level to a change value. After adjusting the liquid level to be the same as the reference value again, close the valve of the small liquid tank, and thereafter measure or record the change value at each measurement point using the same procedure, The liquid level difference Hn is determined by the difference between the change value for each measurement point obtained in this way and the reference value.
, and from this liquid level difference Hn, the relative variation amount Ln is determined by the calculation formula Ln={1+(A0/An)}・Hn, thereby measuring the uneven settlement of the tank. unequal settlement measurement method. 2. In a device for measuring uneven settlement of a tank,
a plurality of small liquid tanks each having a straight cylindrical shape and installed at a plurality of locations where the vertical movement of the tank is to be measured; A reference liquid column pipe that is installed at a reference point that can be considered to be the same installation location as one of the small liquid tanks and that is used as a reference point for sinking of the tank, and this reference liquid column pipe and each of the small liquid tanks. a communication pipe that communicates with the small liquid column and the communication pipe, a valve that is provided between the small liquid tank and the communication pipe that communicates and cuts off the two, and a valve that is provided above the reference liquid column pipe that communicates and cuts off the atmosphere. The atmosphere opening valve, the liquid stored inside these reference liquid column pipes, each small liquid tank and the communication pipe, and one of the small liquid tanks and the reference liquid column pipe in the small liquid tank. a liquid level adjusting means for adjusting the height of the liquid level inside the reference liquid column pipe with the atmosphere release valve closed when the valve is opened and communicated through the communication pipe; ,
and liquid level detection means for detecting the height of the liquid level in the reference liquid column pipe, and the valve and the atmosphere release valve are controlled to open and close simultaneously or at different timings at one location by remote control. An apparatus for measuring uneven settlement of a tank, characterized in that it is configured to be able to measure uneven settlement of a tank. 3. The liquid level adjusting means includes a pressurizing device consisting of a cylinder and a piston, a motor that drives the pressurizing device, and a liquid level adjusting device that controls the rotational drive of the motor according to the output of the liquid level detecting device. Measurement of uneven settlement of a tank according to claim 2, characterized in that the compression chamber of the cylinder is configured to communicate with the upper side of the reference liquid column pipe. Device. 4. The liquid is completely inert and has a high specific gravity;
The apparatus for measuring uneven settlement of a tank according to claim 2, characterized in that the fluid is a highly permeable liquid.