JPH0257935A - Apparatus for monitoring change in liquid level - Google Patents

Abstract

PURPOSE:To detect leakage of liquid from a tank by monitoring the change in liquid level based on the following signal and value: a detected signal from a liquid-level detecting part corresponding to the elapsed time from a time point when the latest detected signal is outputted from a state detecting part; and a preset value regarding the change in liquid level that is determined in correspondence with the elapsed time. CONSTITUTION:Fuel for a boiler 14 is stored in a tank 12. The fuel is supplied into the tank 12 from a supplying pump 11. The fuel is sucked from the tank 12 with a sucking pump 12 and supplied into the boiler 14. A liquid level detector 1 measures the liquid level of the fuel. A state detector 2 detects the states of starting and stopping of the pumps 11 and 13. A setting device 3 determines the preset values regarding the change in liquid level in correspondence with the elapsed time from a time point when the latest starting or stopping states i.e. the ON/OFF states, of the pumps 11 and 13 are outputted from the detector 2. In a monitoring part 4, the measured signal from the detector 1 is compared with the preset value from the setting device 3. When the measured signal exceeds the preset value, a warning K is issued.

Description

[Detailed description of the invention] [Industrial application field]

The present invention is a liquid level change monitoring device that monitors liquid level changes according to the factors that cause the changes and issues an accurate alarm in accordance with the actual situation, and is particularly suitable for detecting liquid leakage from a tank. Regarding.

[Prior art 1] Conventional liquid level change monitoring devices, for example, in the case of a boiler fuel tank, continuously measure the liquid level or take sampling measurements at predetermined intervals, and set the change value to the upper or lower limit. The equipment was monitored by comparing it with each setting value, and predetermined measures such as issuing an alarm or opening/closing a valve were taken accordingly. [Problems to be Solved by the Invention] - g. The causes of changes in the liquid level are: ■ transient ones that occur during a predetermined time period after pump startup, and ■ steady ones that occur during normal operation of the pump. There are various types, such as (2) abnormalities caused by fuel leakage from the tank or pipes while the pump is stopped. With the conventional techniques as described above, it has not been possible to accurately monitor changes in the liquid level of each of the molds. More specifically, it has not been possible to clearly distinguish fuel leaks from tanks or pipes from other causes, and therefore it has been insufficient to accurately monitor changes in the liquid level in accordance with the actual situation. The object of this invention is to solve the problems of the conventional technology, to monitor changes in liquid level depending on the factors that cause the change, and to issue accurate warnings in accordance with the actual situation.In particular, to detect liquid leakage from a tank. An object of the present invention is to provide a liquid level change monitoring device suitable for detection.

[Means to solve the problem]

In order to solve this problem, the liquid level change monitoring device according to the present invention includes: a liquid level detection section that measures the liquid level; and an actuating section that causes a change in the liquid level, such as starting or stopping a pump. a state detection section that detects a state; a detection signal from the liquid level detection section that corresponds to the elapsed time from the time when the latest detection signal was output from the state detection section; and a detection signal determined according to the elapsed time. and a monitoring unit that monitors a change in the liquid level based on the set value related to the change in the liquid level.

[For use]

The monitoring unit receives a detection signal from the liquid level detection unit corresponding to the elapsed time from the time when the latest detection signal was output from the state detection unit, and a setting related to a change in the liquid level determined corresponding to the elapsed time. Since the liquid level changes are monitored based on the
The operating part, for example, transient liquid level changes that occur during a predetermined period of time after the pump starts, and steady liquid level changes that occur when the operating part is operating normally.
Fluid level changes due to tank leakage that may occur while the operating part is stopped are clearly distinguished from each other.

【Example】

Embodiments of the liquid level change monitoring device according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of this embodiment and its surroundings. In the same figure, the liquid level change monitoring device 10 mainly includes a liquid level detector 1, a status detector 2, a setting device 3, and a monitor. It consists of part 4. In addition,
The object of this monitoring is changes in the liquid level in the tank 12. The tank 12 stores fuel for the boiler 14. This fuel is supplied to the tank 12 by the replenishment pump 11 and the extraction pump 13, or is pumped out from the tank 12 and supplied to the boiler 14, and the liquid level of the fuel in the tank 12 changes accordingly. I will do it. The liquid level detector 1 measures the liquid level of the fuel in the tank 12, and the state detector 2 detects whether each of the replenishment pump 11 and the drawing pump 13 is started or stopped. The setting device 3 receives the latest information from each pump 11.12 from the condition detector 2.
The setting value related to the liquid level change is determined in accordance with the elapsed time from the start or stop state, that is, the time when the ON-OFF state is output. The monitoring unit 4 compares the measurement signal from the liquid level detector 1 with the setting value from the setting device 3, and issues an alarm K when the measurement signal exceeds the setting value. The operation of this liquid level change monitoring device 10 will be explained with reference to FIG. 2. FIG. 2 is a time chart showing the relationship between the liquid level and the start/stop state of the pump. In FIG. 2, Pl is the replenishment pump 11 (see FIG. 1,
(same below) is in 0N-OFF state, P2 is pump 1 for pumping
3(7) ON-OFPli state, L represents the liquid iTl level, and both are shown corresponding to the time T on the common horizontal axis. Regarding the time T, six time periods A, B, C, D, E, and F are sequentially set starting from the time when the pump state P2 is turned ON. Time period A is the so-called initial start-up period until the transient change in the liquid level caused by the start-up of the drawing pump 13 is finished. Continued time period B
is a relatively stable steady pumping period. Time period C is the initial period of stoppage, from when the pump state P2 is turned OFF and pumping stops until the transient change ends, and the following time period is a rest period after pumping out fuel. The time period E is a replenishment period corresponding to the operation of the replenishment pump 11, that is, when the pump state P1 is ON, and is relatively short. During time period F, pump status P1 is O.
This is a rest period after refueling until the pump becomes FF and then the pump state P2 turns ON again. Below, pump 13
When the pump is activated, that is, when the pump state P2 is turned on, each of the above-mentioned time periods is repeated in substantially the same way. Now, next, changes in the liquid level L corresponding to each of the above-mentioned time periods, how to detect this, set values related to level changes, etc. will be explained. The point U1 of the liquid level L corresponds to the starting point of the initial start A, and the point U3 corresponds to the ending point of the time period. In time period A, the liquid level L changes in a valley shape from point U1 through point U2 to point U3, and in this time period A, the change ΔL1 from the level value corresponding to point U1 exceeds the set value a. It can be decided to issue an alarm if Moreover, since the liquid level fluctuates relatively greatly during this time period A, the value a is set relatively large accordingly. In other words, if the value a is small, an unnecessary alarm that does not correspond to the actual situation will be issued. Although the change in the liquid level L in this case is in the shape of a trough, generally it often takes the form of a damped oscillation. Even when the liquid level L changes in the damped vibration type, an alarm is issued if the change ΔL1 exceeds the set value a. Time period B corresponds to a substantially straight line portion of level L from point U3 to point U4. In this time period B, a level change value ΔL2 is detected every sampling period ΔTb, and it is determined that an alarm is issued when this detected value ΔL2 exceeds a set value S. That is, the value corresponds to a steady level drop due to fuel pumping during the time ΔTb. Time period C corresponds to a curved portion of level L from point U4 to point U5 that is gently convex upward. This time period C is a kind of transitional period of level change, so
It is determined that an alarm is issued when the change ΔL4 from the level value corresponding to point U4 exceeds a relatively small set value C. If there is no fuel leak during the time period, point U of level L
The horizontal straight line portion (solid line portion) from 5 to point U6 corresponds. If there is a fuel leak, the level L will become a straight line with a downward trend as shown by the broken line. Therefore, in this time period, the sampling period ΔT
A level change value ΔL5 is detected every d, and it is determined that an alarm is issued when this ΔL5 exceeds a set value d. Moreover, the value d depends on the fuel leakage during the time ΔTd. In time period E, from point U6 of level L to point U7,
8 corresponds to the curved portion that is steeply convex upward. Since this time period E is a refueling period, it is determined that an alarm is issued when the change ΔL6 from the level value corresponding to point U6 exceeds a set value e corresponding to a level increase based on refueling. Time period F is from pump state P1 OFF to pump state P
Since this is the idle period until the turn on of level L, if there is no fuel leakage, there will be a horizontal straight line from point U8 of level L to point Ull. If there is a fuel leak, although not shown here, the level L will become a straight line with a downward trend as in the time period. Therefore, in this time period F, a level change value ΔL8 is detected every sampling period ΔTf, and this ΔL
8 exceeds the set value f, it is decided to issue an alarm. This value f depends on the fuel leakage during the time ΔTf. Note that point Ull corresponds to the next ON pump state P2 and corresponds to the above-mentioned point U1. By the way, each of the above set values a, b, c, d, and e. f must be appropriately selected depending on the density, viscosity, volatility, etc. of the liquid. In other words, the liquid level change monitoring device according to the present invention can adjust the density, viscosity, volatility, etc. by selecting each set value. It can be widely applied to monitoring a variety of different liquids, such as

【Effect of the invention】

As explained above, in this invention, the monitoring section
Based on the detection signal from the liquid level detection unit corresponding to the elapsed time from the time when the latest detection signal was output from the state detection unit, and the set value related to the liquid level change determined corresponding to the elapsed time. This monitors changes in the liquid level in the operating part, such as transient liquid level changes that occur during a predetermined period of time after a pump is started, as well as steady liquid level changes that occur when the operating part is operating normally. The level change can be clearly distinguished from the liquid level change due to liquid leakage in the tank, which may occur while the operating part is stopped. Therefore, the present invention has the following superior effects compared to the conventional technology. (1) Since changes in the liquid level are monitored according to various factors that cause the change, it is possible to issue accurate warnings based on the actual situation and take other necessary measures, especially in case of liquid leakage from the tank. It is suitable for detecting. (2) The operating part, for example, the density and viscosity can be determined by selecting the set value related to the change in liquid level, which is determined in response to the elapsed time from the start or stop of the pump. It can be widely applied to monitoring changes in the liquid level of various liquids with different volatility.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention and its peripheral configuration, and FIG. 2 is a time chart showing the relationship between the liquid level and the start/stop state of the pump. Symbol explanation 1: Liquid level detector, 2: Status detector, 3: Setting device, 4: Monitoring unit, 10: Liquid level change monitoring device, 11: Supply pump,
12: Tank, 13: Extraction pump, 14: Boiler. Ryo 1 figure

Claims (1)

[Claims] 1) A liquid level detection section that measures the liquid level; a state detection section that detects each state of starting or stopping the operating section that causes a change in the liquid level; the latest detection signal is output from this state detection section. Monitoring for monitoring liquid level changes based on a detection signal from the liquid level detection unit corresponding to the elapsed time from the time when the liquid level has changed, and a set value related to the liquid level change determined corresponding to the elapsed time. A liquid level change monitoring device comprising: and;