JPH0868706A - Gas line pressure measuring apparatus for liquefied gas tanker - Google Patents

Abstract

PURPOSE: To measure the gas line pressure accurately even when the hull rocks. CONSTITUTION: A peak hold memory circuit 2 stores the maximum gas line pressure measurement 6 of a measuring pressure oscillator 5. When a circuit 14 makes a decision that the hull is in a rocking state exceeding a set level based on a signal received from a hull rocking sensor 12, a switching circuit 16 is switched by a signal delivered from the rocking decision circuit 14 to deliver the maximum value stored in the peak hold memory circuit 2 to a filter circuit 4 while being reset by a pulse signal generated from a timing circuit 3. This constitution realizes accurate measurement of the gas line pressure of a liquefied gas tanker even under stormy weather. In the drawing, 15 represents a display.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas line pressure measuring device for a liquefied gas carrier, and more particularly to a gas line pressure measuring device for a liquefied gas carrier, which enables accurate measurement of the gas line pressure even when the ship is rocking. .

[0002]

2. Description of the Related Art When transporting a liquefied gas, liquid temperature control of the liquefied gas is an extremely important control item. Since the liquid temperature of the liquefied gas is determined by the saturation temperature according to the gas line pressure, the normal gas line pressure is measured and the liquid temperature of the liquefied gas is managed based on the measured value.

A conventional gas line pressure measuring device for a liquefied gas carrier is shown in FIG. 3, which is transmitted from a measuring pressure transmitter 5 (of the gas line pressure) attached to the gas line. The gas line pressure measurement value 6 is input to the gas line pressure measuring device 1 via the input terminal 5a. Reference numeral 4 in FIG. 3 is a filter circuit built in the gas line pressure measuring device 1,
Reference numeral 15 indicates a display device, and reference numeral 15a indicates an output terminal to which the display device 15 is connected.

[0004]

In the case of a liquefied gas carrier, the liquefied gas tank 9 rolls together with the hull from the horizontal state of FIG. 5 (a) when the hull is shaken due to stormy weather, etc., and is shown in FIG. 5 (b). In the tilted state, the liquefied gas 10 temporarily flows into the gas line 11. Then, when the hull returns to the original horizontal state, the liquefied gas flowing into the gas line 11 as shown in FIG.
To fall. At this time, the gas line pressure temporarily drops. That is, the gas line pressure becomes temporarily lower than the true gas pressure 8, and this is measured by the measurement pressure transmitter 5 and input to the gas line pressure measuring device 1 as the gas line pressure measurement value 6. Become.

By the way, in the conventional gas line pressure measuring device 1 as described above, the filter circuit 4 (first-order lag filter) is provided in order to smooth the signal with noise. Therefore, the above gas line pressure measurement value 6 is processed by the filter circuit 4, and as shown in FIG.
There is a problem that the average value 7 of the gas line pressure measurement values 6 is displayed as a measurement result of the gas line pressure measurement device 1 and a value lower than the true gas pressure 8 is displayed on the display device 15 as a measurement result. is there. It is an object of the present invention to provide a gas line pressure measuring device for a liquefied gas carrier, which solves such problems.

[0006]

In order to achieve the above object, a gas line pressure measuring device in a liquefied gas carrier according to claim 1 is provided with a measuring pressure transmitter for measuring the pressure of the gas line. It has a filter circuit to which the gas line pressure measurement value obtained by the measurement pressure transmitter is input, and a display device to which the output value of the filter circuit is input, and stores the maximum value of the gas line pressure measurement value. Also, a peak hold storage circuit that can always output the stored value, a swing determination circuit that inputs a ship motion signal from the ship motion sensor and outputs an ON signal when the ship motion is above a set value, and the motion measurement circuit Timing circuit for generating a pulse signal when an ON signal from the filter is input, and an input circuit of the filter circuit when an ON signal from the oscillation determination circuit is input And a switching circuit that operates so as to switch to the output circuit of the peak hold storage circuit, and the peak hold storage circuit is configured to be reset by a pulse signal input from the timing circuit. There is.

The gas line pressure measuring device for a liquefied gas carrier according to a second aspect of the present invention is the gas line pressure measuring device for a liquefied gas carrier according to the first aspect, wherein an ON signal is manually applied to the sway determination circuit. The feature is that a manual operation switch for outputting is connected.

[0008]

In the gas line pressure measuring device for a liquefied gas carrier of the present invention described above, when the motion of the hull exceeds a set value, an ON signal is output from the motion determining circuit, and the switching circuit operates in response to this ON signal. Then, the gas line pressure measurement value obtained by the measurement pressure transmitter is input to the filter circuit via the peak hold storage circuit. At the same time, the timing circuit operates to generate a pulse signal, and the stored value of the peak hold storage circuit is reset every time the pulse signal is input to the peak hold storage circuit.

Therefore, the stepped output of the peak hold storage circuit reset for each pulse signal is input to the filter circuit, which is processed by the filter circuit and displayed on the display device. Further, by manually operating the manual operation switch, the gas line pressure can be arbitrarily measured using the peak hold storage circuit.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A gas line pressure measuring device in a liquefied gas carrier as an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is its schematic system diagram and FIG. 2 is its time schedule diagram. 1 and 2, the same reference numerals as those in Figs. 3 to 5 indicate almost the same members or contents.

As shown in FIG. 1, a gas line pressure measuring device 1 of this embodiment has an input terminal 5a and a display device to which a measuring pressure transmitter 5 (of gas line pressure) attached to a gas line is connected. Output terminal connected 15
15a and a filter circuit 4 are provided, and in addition, between the input terminal 5a and the filter circuit 4,
A peak hold storage circuit 2 is provided, and a gas line pressure measurement value 6 as an output signal of the measurement pressure transmitter 5 is output.
Is input to the filter circuit 4 directly through the switching circuit 16 and the peak hold storage circuit 2 or without passing through the peak hold storage circuit 2.

In addition to the above, the gas line pressure measuring device 1 is provided with a sway determination circuit 14, a timing circuit 3 and a manual operation switch 13, and the sway determination circuit 14 outputs the output of the hull sway sensor 12 to the terminal 12a. The output of the fluctuation determination circuit 14 is input to the timing circuit 3 and the switching circuit 16, and the output of the timing circuit 3 is input to the peak hold storage circuit 2. There is.

The timing circuit 3 is the peak hold circuit 2.
A reset pulse for controlling the timing of the peak hold in the above is transmitted, and the output is started upon receiving the "ON" signal from the fluctuation determination circuit 14. The peak hold storage circuit 2 stores the maximum value (peak value) of the gas line pressure measurement value 6 and constantly outputs that value, and
Upon receiving the pulse signal from the timing circuit 3, the stored value is reset.

The sway determination circuit 14 determines whether or not the sway of the ship is above a set value, and "ON" when the sway of the ship is above a measured value.
The signal is output to the timing circuit 3 and the switching circuit 16.
It is also possible to arbitrarily output the "ON" signal from the motion determination circuit 14 to the timing circuit 3 by manually operating the manual operation switch 13 "ON".

In the switching circuit 16, the gas line pressure measurement value 6 obtained by the measurement pressure transmitter 5 is normally input to the filter circuit 4, and the fluctuation determination circuit
When the "ON" signal is input from 14, the input circuit of the filter circuit 4 is switched so that the output of the peak hold storage circuit 2 is input to the filter circuit 4.

In the above-mentioned structure, the hull sways,
When the shaking exceeds the set value, the shaking judgment circuit 14 outputs an "ON" signal 14a (see "Output of shaking judgment circuit" in FIG. 2). At this time, the measurement pressure transmitter 5
The gas line pressure measurement value 6 output from is temporarily lower than the true pressure 8 (curve 8a) and rises and falls as shown by the curve 6a of "output of measurement pressure transmitter" in FIG.
In addition, the motion determination circuit 14 is connected to the motion sensor 12 of FIG.
The hull motion signal as indicated by the curve 12a of "output of hull motion sensor" in FIG.

When the motion determination circuit 14 outputs the signal 14a, the switching circuit 16 operates and the gas line pressure measurement value 6 obtained by the measurement pressure transmitter 5 is passed through the peak hold storage circuit 2. The pulse signal is input to the filter circuit 4, and at the same time, the timing circuit 3 operates to generate the pulse signal 3a, which is input to the peak hold storage circuit 2.

Therefore, the maximum value of the gas line pressure measurement value 6 is input from the peak hold storage circuit 2 to the filter circuit 4 while being reset every pulse signal 3a. Then, the input becomes as shown by the stepped line 2a of "output of the peak hold storage circuit" in FIG. Then, this is processed by the filter circuit 4, and the display value indicated by the curve 8b is displayed on the display device 15. The curve 8b is a curve approximate to (the curve 8a of) the true pressure 8.

Further, by manually turning on the manual operation switch, an "ON" signal can be output from the motion determination circuit 14, whereby the gas line pressure using the peak hold storage circuit 2 can be set at any time. Can be measured.

[0020]

As described in detail above, according to the gas line pressure measuring device in the liquefied gas carrier of the present invention, the following effects and advantages can be obtained. (1) It is possible to measure the gas line pressure of a liquefied gas carrier very accurately even in the case of stormy weather. (2) By operating the manual operation switch, it is possible to measure the gas line pressure more accurately at any time.

[Brief description of drawings]

FIG. 1 is a schematic system diagram of a gas line pressure measuring device in a liquefied gas carrier as one embodiment of the present invention.

FIG. 2 is the same time schedule diagram.

FIG. 3 is a schematic system diagram of a gas line pressure measuring device in a conventional liquefied gas carrier.

FIG. 4 is a measurement result diagram in the same storm.

FIG. 5 (a) is a schematic view showing the inclination of the liquefied gas tank due to the motion of the hull during rough weather, showing the horizontal state of the tank. (b) The figure which shows the rolling state to the same right side. (c) The figure which shows the state returned to the same level.

[Explanation of symbols]

 1 Gas line pressure measuring device 2 Peak hold memory circuit 3 Timing circuit 4 Filter circuit 5 Measuring pressure transmitter 5a Input terminal 6 Gas line pressure measurement value 7 Average value 8 True gas pressure 9 Liquefied gas tank 10 Liquefied gas 11 Gas line 12 Ship motion sensor 13 Manual operation switch 14 Motion determination circuit 15 Display device 15a Output terminal 16 Switching circuit

Claims (2)

[Claims] 1. A device for measuring the pressure of a gas line in a liquefied gas carrier, comprising a measuring pressure transmitter for measuring the pressure of the gas line, and a gas line pressure measurement value obtained by the measuring pressure transmitter. A peak hold memory circuit having a filter circuit to be input and a display device to which an output value of the filter circuit is input, for storing the maximum value of the gas line pressure measurement value and capable of constantly outputting the storage value, A sway determination circuit that outputs the ON signal when the ship sway signal from the ship sway sensor is input and the ship sway is above a set value, and the timing that a pulse signal is generated when the ON signal from the sway measurement circuit is input. Circuit and the output circuit of the peak hold storage circuit when the ON signal from the fluctuation determination circuit is input A gas line pressure in a liquefied gas carrier, wherein the peak hold storage circuit is configured to be reset by a pulse signal input from the timing circuit. Measuring device. 2. The gas line pressure measuring device for a liquefied gas carrier according to claim 1, wherein a manual operation switch for outputting an ON signal by manual operation is connected to the motion determination circuit. , Gas line pressure measuring device in liquefied gas carrier.