JP5534278B1 - Tilt monitoring system and method for liquid storage tank - Google Patents

Abstract

Inclination monitoring of a liquid storage tank capable of estimating and monitoring the inclination of the liquid storage tank using a liquid level gauge that measures the liquid level of the liquid stored in the liquid storage tank Systems and methods can be provided.
A system 200 for monitoring an inclination of a liquid storage tank 100, wherein the height of a liquid level Ls of a liquid Lq stored in the liquid storage tank 100 is different in at least three plan views. The liquid level gauges M [1], M [2], M [3] to be measured in step 1 and the estimated value of the inclination of the liquid level Ls are calculated based on the measured values by the liquid level gauge. And a monitoring device 230 that monitors the inclination of the storage tank 100.
[Selection] Figure 2

Description

  The present invention relates to a technique for monitoring the inclination of a tank for storing a liquid (hereinafter referred to as “liquid storage tank”, sometimes abbreviated as “tank”), and more specifically, stored in the liquid storage tank. The present invention relates to a technique for monitoring the inclination of a liquid storage tank by measuring the height of a liquid level (hereinafter, sometimes referred to as “liquid level”) at at least three different measurement points in plan view.

  When installing a liquid storage tank on a soil structure (hereinafter sometimes referred to as a “base”) that uses the ground or the soil itself as a constituent material, due to the effects of its own weight and load (mainly the weight of the tank and the liquid), There is a case where at least a part of the substrate sinks and the liquid storage tank tilts.

  Such inclination of the liquid storage tank may become apparent with the passage of time, or it may occur in the short term or suddenly due to an earthquake, accident, etc., but it is not basically desirable. Since it is sometimes dangerous, the presence or degree of the inclination is measured, and the result is used for tank monitoring, defect detection, inspection, maintenance, and the like.

  As a method for measuring the inclination of the liquid storage tank, for example, (1) the inclination of the tank itself is measured by installing an inclinometer on a constituent member or an attached part of the liquid storage tank (Patent Document 1), (2 ) Install a settlement meter on the base to measure the deformation of the base (Patent Document 2). Thus, there is a technique of knowing the inclination of the tank installed on the base (hereinafter, this conventional technique is referred to as “conventional technique 1”).

  On the other hand, there is an example in which the liquid level stored in the liquid storage tank is measured by a liquid level gauge, and the result is used for tank monitoring, fault detection, inspection, maintenance, etc. (Patent Document) 1, 3 to 6) (hereinafter, this prior art is referred to as “prior art 2”).

Japanese translation of PCT publication No. 3-503684 Japanese Utility Model Publication No.3-3627 Japanese Utility Model Publication No. 61-75827 JP-A-2005-180240 JP-A-62-159017 JP-A-6-260689

  However, the inclinometer and the subsidometer in the prior art 1 are not liquid level meters, and conversely, the liquid level meter in the prior art 2 is not an inclinometer or subsidometer. In addition, the liquid level gauge in the prior art 2 can measure the height of the liquid level of the liquid stored in the tank in a plurality of different ways in plan view, no matter how it is combined with the inclinometer or the settlement meter in the prior art 1. It is impossible to measure the liquid level at a point.

  The present invention has been made in view of the above circumstances, and estimates and monitors the inclination of the liquid storage tank using a level gauge that measures the liquid level of the liquid stored in the liquid storage tank. It aims at providing the technology to do.

In order to achieve the above object, the liquid storage tank inclination monitoring system according to the first embodiment of the present invention is different in at least the height of the liquid level of the liquid stored in the liquid storage tank in plan view. A liquid level meter to be measured at three measurement points, and a normal vector of the surface of the liquid based on a measurement value by the liquid level meter or a three-dimensional angle formed by the normal vector and a reference vector , a monitoring device for monitoring the inclination of at least the normal vector or said liquid storage tank based on the angle of the three-dimensional, a recording apparatus for storing the data corresponding to the time an angle of at least the normal vector or the three-dimensional , Having a feature.

The liquid storage tank inclination monitoring system according to the second aspect of the present invention is the liquid storage tank inclination monitoring system according to the first aspect, further comprising an output device, wherein the monitoring apparatus comprises the The data read from the recording device is further subjected to signal processing and then sent to the output device .

A liquid storage tank inclination monitoring system according to a third embodiment of the present invention is a system for monitoring the inclination of a plurality of liquid storage tanks, and the liquid liquid stored in each liquid storage tank. A liquid level meter that measures the height of the surface at at least three measurement points that differ in plan view, and a normal vector of the surface of the liquid based on a measurement value by the liquid level meter, or a vector that is a reference to the normal vector A monitoring device that calculates a three-dimensional angle formed by each of them and monitors an inclination of the individual liquid storage tank based on at least the normal vector or the three-dimensional angle ; and at least the normal vector or the three-dimensional a recording apparatus for storing the data corresponding to angle time and has a, the monitoring device is installed in a place which is spaced apart from the respective liquid storage tank, the liquid level meter A receiving apparatus for receiving that measurements by radio, in which particular with the features.

A tilt monitoring method for a liquid storage tank according to a fourth embodiment of the present invention is a method for monitoring the tilt of a liquid storage tank, wherein the height of the liquid level stored in the liquid storage tank is determined. A first step of measuring with a liquid level meter at at least three measurement points different from each other in plan view, and a normal vector of the surface of the liquid based on a measured value by the liquid level meter or a vector serving as a reference with the normal vector A second step of calculating a three-dimensional angle formed by: a third step of monitoring at least the normal vector or an inclination of the liquid storage tank based on the three-dimensional angle ; and at least the normal vector Or a fourth step of recording the three-dimensional angle as data corresponding to time .

A liquid storage tank inclination monitoring method according to a fifth aspect of the present invention is the liquid storage tank inclination monitoring method according to the fourth aspect, wherein the data recorded in the fourth step is read out. And a fifth step of outputting the signal after further signal processing .

A liquid storage tank inclination monitoring method according to a sixth aspect of the present invention is the liquid storage tank inclination monitoring method according to the fourth or fifth aspect, wherein the measured value by the liquid level gauge is wirelessly transmitted. The method further includes a step of transmitting, wherein the second step is a step of calculating the normal vector or the three-dimensional angle based on a wirelessly received measurement value by the liquid level gauge. It is what you have.

According to each of the first and fourth embodiments of the present invention, the normal vector of the surface of the liquid or the normal vector and the reference based on the measured value by the liquid level gauge of the liquid stored in the liquid storage tank The three-dimensional angle formed by the vector is calculated, and the inclination of the liquid storage tank is monitored based on at least the normal vector or the three-dimensional angle, and at least the normal vector or the three-dimensional angle is monitored. Is stored as data corresponding to time, so even if the amount of data to be stored is enormous, such as when data acquisition is long-term or when data acquisition frequency per unit time is high, the storage capacity There is an effect that a large recording apparatus can be dispensed with.

According to the 2nd and 5th form of this invention, the monitoring apparatus (5th process) can be actualized.

  According to the third aspect of the present invention, the inclination of each individual tank is estimated by measuring the liquid level of the liquid stored in each of the plurality of tanks with a plurality of liquid level gauges, Some wireless remote monitoring can be performed, and at that time, it is not necessary to install a dedicated instrument (inclinometer or subsidometer) to measure the inclination of each tank and measure the inclination of the tank.

  According to the sixth aspect of the present invention, it is possible to estimate the inclination of the tank by measuring the level of the liquid stored in the tank with a plurality of liquid level gauges, and to perform remote monitoring partially wirelessly. At that time, it is not necessary to install a dedicated instrument (inclinometer or subsidence meter) to measure the inclination of the tank and measure the inclination of the tank.

  In addition, this invention does not exclude the adoption of a dedicated instrument (an inclinometer or a settlement meter) for measuring the inclination of the tank in any form of the present invention. Even when the inclination of the liquid storage tank is measured by the dedicated device, as long as the inclination monitoring system or the inclination monitoring method of the liquid storage tank according to the present invention is adopted, it is out of the scope of the present invention. Must not.

  Further, in each of the third and sixth aspects of the present invention, signal transmission is performed partially wirelessly, but in other aspects of the present invention, a wired system or a wireless system may be used. Also good.

It is a schematic sectional drawing which shows the tank for liquid storage provided with the inclination monitoring system of this invention. It is a block diagram which shows the inclination monitoring system of this invention. The liquid level Ls of the liquid Lq stored in the liquid storage tank 100 is measured by a total of three liquid level meters M [1], M [2], and M [3] installed at three different measurement points. It is explanatory drawing about a case, (a) is explanatory drawing which looked at the liquid level Ls from diagonal, (b) is explanatory drawing which looked at the liquid level Ls from right above. The liquid level Ls of the liquid Lq stored in the liquid storage tank 100 is converted into a total of four or more liquid level meters M [k] (k = 1, 2, 3, 3) installed at four or more different measurement points. 4,..., N) (n is an integer greater than or equal to zero). It is a block diagram which shows another inclination monitoring system of this invention.

  Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. At that time, the description will be made with reference to the drawings as necessary, but the same portions or corresponding or common portions in the respective drawings are denoted by the same reference numerals, and a part of the description is omitted.

  The embodiments described below are preferred specific examples of the present invention, and various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. As long as there is no description of the effect, it is not restricted to the said embodiment.

  FIG. 1 is a schematic sectional view showing a liquid storage tank equipped with the tilt monitoring system of the present invention.

  In FIG. 1, the liquid storage tank 100 is a double shell tank including an outer shell 110 and an inner shell 120 constructed on a base (not shown), and a first space 130 is formed inside the inner shell 120. A second space 140 is provided between the outer shell 110 and the inner shell 120, and the liquid Lq is accommodated and stored in the first space 130.

  The inner shell 120 has an opening H at the top or top.

  A spacing material 150 is interposed between the outer shell 110 and the inner shell 120. The spacing member 150 has a gap large enough to allow the liquid Lq to move, and does not hinder the movement of the liquid Lq. A typical example of the spacing member 150 is a truss structure bonding material sufficient to ensure strength and distance.

  The top or top of the inner shell 120 is sealed with an upper lid 160. The upper part of the outer shell 110 is inclined to the inner shell 120 side and connected to the upper end of the inner shell 120, thereby sealing between the inner shell 120 and the outer shell 110.

  The first lid portion C is provided on the upper lid portion 160 so as to communicate with the first space 130 when the first lid portion C is opened. The second lid portion E is provided on the upper portion of the outer shell portion 110 so as to communicate with the second space 140 when the second lid portion E is opened.

  In the liquid storage tank 100, when the liquid level Ls reaches the storage upper limit Lm, the liquid Lq exceeding the storage upper limit Lm moves from the first space 130 to the second space 140 through the opening H. It is configured. In other words, in the liquid storage tank 100, a portion of the liquid Lq that has entered the outer shell 110 that exceeds the storage upper limit Lm of the first space 130 is stored in the second space 140. .

  The first liquid discharge path that allows the liquid to move from the first space 130 to the outside of the outer shell 110, and the first liquid that allows the liquid to move from the second space 140 to the outside of the outer shell 110. At least one of the two liquid discharge paths (both with an open / close valve) may be provided. In the example of FIG. 1, a liquid discharge path 170 is attached to the outer shell 110 via an opening / closing valve 171.

  According to the liquid storage tank 100 having such a configuration, the storage of the liquid Lq is performed exclusively in the first space 130, and the amount of the liquid Lq exceeds the storage upper limit Lm of the first space 130 for some reason. In this case, since the excess amount of the liquid Lq can be stored in the second space 140, there is no possibility that the liquid Lq flows out of the outer shell 110. In that sense, the liquid storage tank 100 is suitable for long-term storage (storage for at least one year) of the liquid Lq, and is more preferable when the liquid Lq is a harmful substance or contains a harmful substance.

  The liquid level meter M is an instrument that is installed in the tank 100 and measures the liquid level of the liquid level Ls from the initially set reference position. A typical example of the reference position is a position at the storage upper limit Lm or a position separated from the position by a known predetermined distance.

  When the level gauge M is installed in the tank 100, a measuring pipe, a compartment, a small sub tank, etc. are provided in the tank 100, and the level gauge M is installed therein. You may comprise so that a liquid level meter may not be exposed to the bulk part of the liquid Lq.

  The liquid level meter M may be a commercially available liquid level meter. When there are a plurality of candidates (an optional liquid level meter), one that is more suitable for the use environment may be selected.

  At least three liquid level meters M are prepared. The at least three liquid level gauges M are preferably the same manufacturer and the same model and model, but this need not be the case.

  The following description relates to the case where there are three liquid level meters M, unless otherwise described. Assume that the three liquid level meters M have M [1], M [2] and M [3]. When there are four or more liquid level gauges M (k = 1, 2, 3, 4,..., N) (n is an integer greater than or equal to zero), any (different) three liquid level gauges M can be selected. The following description applies to any three liquid level gauges M.

  Next, the tilt monitoring system 200 will be described below with reference to FIGS. In FIG. 2, the interface for signal input and output is omitted as it naturally exists.

  The inclination monitoring system 200 transmits a liquid level meter M [k] (three liquid level meters M [1], M [2] and M [3] as described above) installed in the tank 100, and transmission. A device 210, a receiving device 220, a monitoring device 230, a recording device 240, an input device 250, and an output device (including a display device) 260 are provided. Typical examples of the output device 260 are a monitor and a printing device.

  The monitoring device 230 is installed with a basic software program for controlling basic operations of the devices constituting the inclination monitoring system 200 and a computer program essential for executing the inclination monitoring of the tank 100. The monitoring device 230 controls the tilt monitoring system 200 by executing the computer program. The signal processing executed in the monitoring device 230 will be described later.

  The liquid level gauges M [1], M [2], and M [3] are all liquid levels S [1] (t), S [of the liquid level Ls from the initially set reference position at time t. 2] (t) and S [3] (t) are measured, a signal corresponding to each measured value is generated, and sent to the transmission device 210.

  The transmission device 210 wirelessly transmits the signal at time t sent from the liquid level gauges M [1], M [2] and M [3] to the reception device 220. Note that the installation location of the transmission device 210 is usually outside the tank 100. The outside of the tank 100 means a place on the outer surface of the outer shell 110 of the tank 100 that is slightly separated from the outer shell 110. If the usage environment permits, the installation location of the transmission device 210 may be inside the outer shell 110.

  The receiving device 220 receives the signal transmitted from the transmitting device 210 and sends the received signal to the monitoring device 230.

  Signal transmission from the transmission device 210 to the reception device 220 is a wireless method, but may be a wired method.

  The signal sent to the monitoring device 230 is also sent to the recording device 240, and is stored as data at time t in a format readable by the recording device 240.

  The monitoring device 230 executes signal processing executed by the installed computer program using the signal sent from the receiving device 220 and the signal read from the recording device 240. The execution result is stored as data in a format that can be read by the recording device 240, and (i) at the same time or (ii) after the recording device 240, or (iii) after the recording device 240 from the monitoring device 231. After being read out and further subjected to necessary signal processing in the monitoring device 230, it is sent to the output device 260.

  The monitoring device 230 generates a specific signal and sends it to the output device 260 when the estimated value of the inclination of the tank 100 exceeds a predetermined value. In response to the specific signal, the output device 260 outputs a warning and displays a warning for the tank.

  A typical example of the input device 250 is a keyboard input unit, which sends necessary data and operation instructions to the monitoring device 230 and sends an operation instruction signal.

  In the inclination monitoring system 200, an inclinometer T is attached to the tank 100, and a signal at time t from the inclinometer T is wirelessly transmitted from the transmission device 210 to the reception device 220, and is transmitted from the reception device 220 to the monitoring device 230. Thus, it may be used for signal processing in the monitoring device 230.

  For example, in the monitoring device 230, information about the inclination of the tank 100 obtained by processing signals sent from the liquid level gauges M [1], M [2] and M [3] can be obtained from the inclinometer T. The signal sent from the liquid level gauges M [1], M [2] and M [3] is corrected by the information about the inclination of the tank 100, or conversely, the information about the inclination of the tank 100 obtained from the inclinometer T. You may process so that it may correct with the information regarding the inclination of the tank 100 obtained by processing.

  Information on the inclination of the tank 100 obtained from the inclinometer T and information on the inclination of the tank 100 obtained by processing signals sent from the liquid level gauges M [1], M [2] and M [3] It can also be estimated by logical operation whether the tank 100 is truly inclined, whether the inner shell 120 in the tank 100 is abnormal, or whether an abnormality has occurred in the liquid level gauge.

  Next, among the signal processing executed by the computer program installed in the monitoring device 230, the one relating to the inclination monitoring system and the inclination monitoring method for the liquid storage tank according to the present invention will be described with reference to FIGS. I will explain.

  In the following description, the liquid level Ls is regarded as a plane (approximate). The liquid level at the beginning (time t = 0) is Ls (0), and the liquid level at time t is Ls (t). Furthermore, as described above, the liquid level meter M [k] installed in the tank 100 is an instrument that measures the liquid level of the liquid level Ls from the set reference position, and therefore, here, the storage upper limit. A position separated by a predetermined distance from Lm is set as the reference position.

  FIG. 3 shows a total of three liquid level gauges M [1], M [2], M [3] installed at three different measurement points for the liquid level Ls of the liquid Lq stored in the liquid storage tank 100. ] (A) is an explanatory diagram when the liquid level Ls is viewed from an oblique direction, and (b) is an explanatory diagram when the liquid level Ls is viewed from directly above.

  In FIG. 3, the liquid levels measured by the three liquid level gauges M [1], M [2], and M [3] for the liquid level Ls (0) are respectively S [1] (0) and S [2 ] (0), S [3] (0), the liquid levels measured by the three liquid level gauges M [1], M [2], M [3] for the liquid level Ls (t) are respectively S Assuming that [1] (t), S [2] (t), and S [3] (t), the liquid level is changed to three liquid level gauges M [1], M by elapse of time t from the beginning. At each position of [2] and M [3], S [1] (t) -S [1] (0), S [2] (t) -S [2] (0), S [3] (t) -S [3] (0). For convenience of explanation, if it is defined in advance that S [1] (0) = 0, S [2] (0) = 0, and S [3] (0) = 0, time t elapses from the beginning. As a result, the liquid level Ls becomes S [1] (t), S [2] (t), S at each position of the three liquid level gauges M [1], M [2], and M [3]. [3] It has changed by (t).

[How to find the slope (1)]
When the coordinates of three different points in the three-dimensional coordinates are known, the plane on which the three points are uniquely determined. Therefore, the liquid level Ls (0) at time t = 0 and the liquid level Ls (t) at time t are also uniquely determined. Therefore, the equation of the plane of the liquid level Ls (t) is changed to a reference plane of three-dimensional coordinates (if the XYZ three-dimensional orthogonal coordinates are arbitrarily defined, the XY plane, YZ plane, XZ By projecting onto the plane, the inclination of the liquid level Ls (t) on the reference plane can be obtained.

  In addition, since the shape of the horizontal cut surface inside the tank 100 (inner shell 120) in the vicinity of the measurement points of the three liquid level gauges M [1], M [2], M [3] and the vicinity thereof is known, By projecting the plane equation of Ls (t) onto the wall surface of the inner shell 120, the inclination of the liquid level Ls (t) at the projection location can also be obtained.

[How to find the slope (2)]
When the coordinates of three different points are known in the three-dimensional coordinates, the normal vector of the plane on which the three points are placed is uniquely determined. Specifically, for example, a vector having S [1] (t) as a start point and S [3] (t) as an end point is A <13> (t), and S [1] (t) is a start point. [2] When B <12> (t) is a vector whose end point is (t), the outer product of A <13> (t) and B <12> (t) (from A <13> (t) Normal vector N <312> (t) or vector n <312> (t) normalized to normal vector N <312> (t) corresponding to B <12> (t) counterclockwise outer product) ). If the liquid surface Ls (t) is represented by this normal vector, the inclination of the liquid surface Ls (t) can be obtained in the same manner as in the above [How to obtain the inclination (part 1)].

  Note that N (0) in FIG. 3 is N <312> (0) (normal vector N <312> (t) at time t = 0). N (0) is a vector starting from S [1] (0) and ending at S [3] (0) as A <13> (0), and starting from S [1] (0) as S [ 2] When B <12> (0) is a vector ending at (0), the outer product of A <13> (0) and B <12> (0) (from A <13> (0) to B It can also be said to be a normal vector corresponding to <12> (0) counterclockwise outer product).

  The angle (three-dimensional) K <312> (t) formed by the two vectors N <312> (0) and N <312> (t) is directly connected to the inclination of the liquid level Ls (t). Instead of 312> (t), K <312> (t) may be monitored.

  The advantage of [Determining the inclination (No. 2)] is that the amount of information of the representative value (normal vector) of the liquid level Ls (t) can be reduced. In general, if data acquisition is performed over a long period of time, and if the frequency per unit time of data acquisition is increased, the amount of data to be stored becomes enormous and handling becomes difficult. In addition, the recording device 240 having a large storage capacity must be employed. However, according to [How to find inclination (part 2)], the manifestation of these problems can be delayed.

  FIG. 4 shows the liquid level Ls of the liquid Lq stored in the liquid storage tank 100 with a total of four or more liquid level gauges M [k] (k = 1, k) installed at four or more different measurement points. 2, 3, 4,..., N) (where n is an integer equal to or greater than zero).

  In FIG. 4, the liquid levels measured by four or more liquid level meters M [k] for the liquid level Ls (0) are respectively S [1] (0), S [2] (0), S [3 ] (0), S [4] (0), ..., S [n] (0), and the liquid level measured by four or more liquid level gauges M [k] for the liquid level Ls (t) , S [1] (t), S [2] (t), S [3] (t), S [4] (t), ..., S [n] (t) When the time t elapses, the liquid level becomes S [1] (t) -S [1] (0), S [2] at each position of four or more liquid level meters M [k]. (t) -S [2] (0), S [3] (t) -S [3] (0), S [4] (t) -S [4] (0),. n] (t) −S [n] (0)). For convenience of description, if it is defined in advance that S [k] (0) = 0 (k = 1, 2, 3, 4,..., N) (n is an integer equal to or greater than zero), the time t from the beginning As time elapses, the liquid level becomes S [1] (t), S [2] (t), S [3] (t) at each position of four or more liquid level gauges M [k]. , S [4] (t),..., S [n] (t).

[How to find the slope (3)]
The basic way of finding this is the same as [How to find the slope (part 1)]. S [1] (t), S [2] (t), S [3] (t), S [4] (t), ..., S [n] (t) Points S [p] (t), S [q] (t), and S [r] (t) are selected. When the coordinates of three different points are known in the three-dimensional coordinates, the plane on which the three points are placed is uniquely determined. Therefore, the liquid level Ls (t) at time t is also uniquely determined. Accordingly, by projecting the plane equation of the liquid level Ls (t) onto the reference plane in three-dimensional coordinates, the inclination of the liquid level Ls (t) on the reference plane can be obtained. Further, by projecting the plane equation of the liquid level Ls (t) onto the wall surface of the inner shell 120, the inclination of the liquid level Ls (t) at the projection location can also be obtained.

[How to find the slope (3a)]
S [1] (t), S [2] (t), S [3] (t), S [4] (t), ..., S [n] (t) Points S [p1] (t), S [p2] (t), and S [p3] (t) are selected, and an expression of a plane on which the three points are placed is obtained. Assuming that the expression of this plane is a (p) · x + b (p) · y + c (p) · z + d (p) = 0 in the XYZ three-dimensional orthogonal coordinates. Select another arbitrary three different points S [q1] (t), S [q2] (t), S [q3] (t), and the equation of the plane on which the three points lie is a (q) · x + b It is assumed that (q) · y + c (q) · z + d (q) = 0. Furthermore, any other three different points S [r1] (t), S [r2] (t), S [r3] (t) are selected, and the expression of the plane on which the three points are placed is a (r) x + b (r) .y + c (r) .z + d (r) = 0. (Hereafter, the setting of the plane formula is repeated as necessary.) Thereafter, the average values of the coefficients a, b, c and intercept d of the variables x, y, z in all plane formulas are taken, and a The formula of the plane set by setting @, b @, c @, d @ is a @ • x + b @ • y + c @ • z + d @ = 0, and this formula expresses the liquid level Ls (t). It is considered. Thereafter, by projecting this equation onto the reference surface of the three-dimensional coordinates, the inclination of the liquid level Ls (t) on the reference surface can be obtained. Further, by projecting this equation onto the wall surface of the inner shell 120, the inclination of the liquid level Ls (t) at the projection location can also be obtained.

[How to find the slope (3b)]
The point sequence S [1] (t), S [2] (t), S [3] (t), S [4] (t),. The method of obtaining the plane equation is well known. The formula of the plane obtained using this method is set as a @ · x + b @ · y + c @ · z + d @ = 0, and this formula is regarded as a formula expressing the liquid level Ls (t). Thereafter, by projecting this equation onto the reference surface of the three-dimensional coordinates, the inclination of the liquid level Ls (t) on the reference surface can be obtained. Further, by projecting this equation onto the wall surface of the inner shell 120, the inclination of the liquid level Ls (t) at the projection location can also be obtained.

[How to find the slope (4)]
The basic way of finding this is the same as [How to find the slope (part 2)]. First, S [1] (t), S [2] (t), S [3] (t), S [4] (t),..., S [n] (t) Three different points S [p] (t), S [q] (t), and S [r] (t) are selected. For example, a vector having S [q] (t) as a start point and S [q] (t) as an end point is A <pq> (t), and S [p] (t) is a start point. ) As the end point vector B <pr> (t), the outer product of A <pq> (t) and B <pr> (t) (from A <pq> (t) to B <pr> (t the normal vector N <qpr> (t) corresponding to the counterclockwise outer product to t) or the vector n <qpr> (t) obtained by normalizing the normal vector N <qpr> (t) it can. If the liquid level Ls (t) is represented by this normal vector, the inclination of the liquid level Ls (t) can be obtained in the same manner as in the above [How to obtain inclination (part 2)].

  Note that N (0) in FIG. 4 is a normal vector of the liquid level Ls (0) at time t = 0. The angle (three-dimensional) K <qpr> (t) formed by the two vectors N (0) and N <qpr> (t) is directly connected to the inclination of the liquid surface Ls (t), so that N <qpr> ( Instead of t), K <qpr> (t) may be monitored. This point is also the same as in the case of [How to find inclination (part 2)].

[How to find the slope (4a)]
After obtaining the plane equation a @ · x + b @ · y + c @ · z + d @ = 0 by [Determining the Inclination (Part 3a)], the normal vector of the plane is obtained, and the liquid level Ls ( If t) is represented, the inclination of the liquid level Ls (t) can be obtained in the same manner as in the above [How to obtain inclination (part 2)].

[How to find the slope (4b)]
After obtaining the equation of the plane as a @ · x + b @ · y + c @ · z + d @ = 0 by [How to find the inclination (3b)], the normal vector of the plane is obtained, and the liquid level Ls is obtained from the normal vector. If (t) is represented, the inclination of the liquid level Ls (t) can be obtained in the same manner as in [How to find the inclination (part 2)].

  The advantages of using normal vectors such as [How to find slope (Part 4)], [How to find slope (Part 4a)] and [How to find slope (Part 4b)] This is the same as the advantage in the case of (How to obtain (Part 2)], and the amount of information of the representative value (normal vector) of the liquid level Ls (t) can be reduced.

  In the above description, the liquid level Ls is regarded as a plane. Therefore, calculating the inclination of the liquid level Ls based on the measurement value obtained by the liquid level gauge does not leave the range of calculation (approximation) of the estimated value of the inclination, regardless of which method is used. However, the point sequence S [1] (t), S [2] (t), S [3] (t), S [4] (t),. If the inclination of the liquid level Ls is calculated by statistically processing more measurement data, as in the method of obtaining an approximate plane equation (see [How to Obtain Inclination (Part 3b)]), Reliable estimation of tank inclination can be realized.

  Next, another tilt monitoring system 201 will be described with reference to FIG. As in the case of FIG. 2, the illustration of the signal input and output interfaces is omitted in FIG. 5.

  5 includes a monitoring device 231 connected to a common bus line BL, a recording device 241 and a receiving device 221, an input device 251 and an output device 261 connected to the monitoring device 231. Liquid storage tanks 100a, 100b,... 100n. The liquid storage tanks 100a, 100b,... 100n are all the same as the liquid storage tank 100 shown in FIG. 2, and have at least three liquid level gauges for measuring the liquid level of the stored liquid. , And 210n for transmitting signals from the liquid level gauge wirelessly.

  The receiving device 221 receives the signal at time t sent from the transmitting devices 210a, 210b,... 210n by a wireless method and sends it to the bus line BL.

  The recording device 241 accumulates the signal sent from the receiving device 221 to the bus line BL as data at time t in a readable format.

  The monitoring device 231 executes signal processing executed by the installed computer program using the signal sent from the receiving device 221 to the bus line BL and the signal read from the recording device 241 via the bus line BL. . Examples of specific contents of the signal processing are as described above.

  The execution result of the signal processing (particularly, the estimated value of the tank inclination) is sent to the bus line BL and stored as data in a format that can be read by the recording device 241, and (i) at the same time or (ii ) After that, it is read from the recording device 241 via the bus line BL by the monitoring device 230, or (iii) After that, it is read from the recording device 241 via the bus line BL by the monitoring device 231, and a necessary signal is output from the monitoring device 231. After further processing, it is sent to the output device 261.

  The monitoring device 231 generates a specific signal when the estimated value of the inclination of the specific tank 100x exceeds a predetermined value among the tanks 100a, 100b,... 100n, and sends the specific signal to the output device 261. In response to the specific signal, the output device 261 outputs a warning and displays a warning for the tank 100x.

  In the inclination monitoring system 201, inclinometers Ta, Tb,... Tn are attached to the tanks 100a, 100b,... 100n, respectively, and the inclinometers Ta, Tb,. Signals are sent wirelessly from the transmitting devices 221a, 221b,... 221n to the common receiving device 221 and sent from the receiving device 221 to the monitoring device 231 via the bus line BL, and are used for signal processing in the monitoring device 231. May be.

  For example, in the monitoring device 231, information on the inclination of an arbitrary tank 100 k obtained by processing a signal sent from the liquid level gauge is obtained from the tank 100 k obtained from the inclinometer Tk attached to the tank 100 k. The information on the inclination of the tank 100k obtained from the inclinometer Tk is corrected by the information on the inclination of the tank 100k obtained by processing the signal sent from the liquid level gauge. It may be processed.

  The tank 100k is truly tilted by a logical operation of the information about the inclination of the tank 100k obtained from the inclinometer Tk and the information about the inclination of the tank 100k obtained by processing the signal sent from the liquid level gauge included in the tank 100k. It can also be estimated whether the inner shell 120 in the tank 100k is abnormal or whether the liquid level gauge is abnormal.

  According to the inclination monitoring system 201 as shown in FIG. 5, it is possible to monitor the individual inclinations of a large number of tanks 100a, 100b,... Therefore, it is possible to flexibly cope with the expansion of the liquid storage tank after the fact.

  In FIG. 3, A <13> (0) and B <12> (0) are both vectors starting from S [1] (0), and A <13> (t) and B < <12> (t) is drawn as a vector starting from S [1] (t). In general, the vector A and the vector B are drawn as vectors starting from a common point S [1]. However, the vector A and the vector B need to be non-parallel vectors, but do not need to start from a common point.

  The same applies to the vector A and the vector B in FIG. In FIG. 4, A <pq> (t) and B <pr> (t) are drawn as vectors starting from a common point S [p] (t), but they are non-parallel vectors. Although it is necessary, there is no need to start from a common point.

  Further, in FIG. 3, the number k of S [k] is assigned so as to increase clockwise, but it is not necessary to attach the number k as such (see FIG. 4).

100, 100a, 100b, ..., 100n: Liquid storage tank 110: Outer shell 120: Inner shell 130: First space 140: Second space 150: Spacing material 160: Upper lid portion 170: Liquid discharge path 171: Opening / closing valve 200, 201: Inclination monitoring system 210, 211: Transmission device 220, 221: Reception device 230, 231: Monitoring device 240, 241: Recording device 250, 251: Input device 260, 261: Output device (display device) including)
Lm: storage upper limit Lq: liquid Ls: liquid level H: opening C: first lid E: second lid M [1], M [2], M [3], ...: liquid level Total M [k] (k = 1, 2, 3,..., N): kth level gauge S [1], S [2], S [3],...: M [1], M [2], liquid level S [k] measured by M [3],..., K [1, 2, 3,..., N]: liquid level S [k] measured by M [k] (t): S [k] at time t (t ≧ 0)
BL: Bus line T, Ta, Tb, ..., Tn: Inclinometer

Claims (6)

A system for monitoring the inclination of a liquid storage tank,
A liquid level gauge that measures the height of the liquid level of the liquid stored in the liquid storage tank at at least three measurement points different in plan view;
A three-dimensional angle formed by a normal vector of the surface of the liquid or the normal vector and a reference vector is calculated based on a measurement value by the liquid level gauge, and at least the normal vector or the three-dimensional angle is calculated. A monitoring device for monitoring the inclination of the liquid storage tank based on:
A recording device for storing at least the normal vector or the three-dimensional angle as data corresponding to time;
An inclination monitoring system for a liquid storage tank, comprising: The apparatus according to claim 1, further comprising an output device, wherein the monitoring device further performs signal processing on the data read from the recording device and then sends the data to the output device . Inclination monitoring system for liquid storage tanks. A system for monitoring the inclination of a plurality of liquid storage tanks,
A liquid level gauge for measuring the height of the liquid level stored in each liquid storage tank at at least three different measurement points in plan view;
A three-dimensional angle formed by a normal vector of the surface of the liquid or the normal vector and a reference vector is calculated based on a measurement value by the liquid level gauge, and at least the normal vector or the three-dimensional angle is calculated. A monitoring device for monitoring the inclination of the individual liquid storage tanks based on
A recording device for storing at least the normal vector or the three-dimensional angle as data corresponding to time;
With
The monitoring device includes a receiving device that is installed at a location separated from the individual liquid storage tanks and wirelessly receives a measurement value by the liquid level gauge,
An inclination monitoring system for a liquid storage tank. A method of monitoring the inclination of a liquid storage tank,
A first step of measuring the liquid level of the liquid stored in the liquid storage tank with a liquid level gauge at at least three measurement points different in plan view;
A second step of calculating a three-dimensional angle formed by a normal vector of the surface of the liquid or the normal vector and a reference vector based on a measurement value by the liquid level meter;
A third step of monitoring an inclination of the liquid storage tank based on at least the normal vector or the three-dimensional angle ;
A fourth step of recording at least the normal vector or the three-dimensional angle as data corresponding to time;
An inclination monitoring method for a liquid storage tank, comprising: 5. The inclination monitoring of the liquid storage tank according to claim 4, further comprising a fifth step of reading out the data recorded in the fourth step, further performing signal processing and then outputting the data. Method. The method further includes a step of wirelessly transmitting the measurement value obtained by the liquid level gauge, and the second step includes the normal vector or the three-dimensional angle based on the wireless measurement value obtained by the liquid level gauge. The method for monitoring the inclination of the liquid storage tank according to claim 4 or 5, wherein

Images