JPH0358650B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dry-up detection device for detecting whether the bottom of a cargo oil tank in a tanker is dry after cleaning crude oil.

[Conventional technology]

FIG. 6 is a schematic configuration diagram of a tanker equipped with a conventional dry-up detection device, and FIG. 7 is a configuration diagram of the dry-up detection device. In the figure, 1 is a tanker, 2 is a cargo oil tank of the tanker 1, 3 is a pump room, 4 is an engine room, and 5 is a cargo handling control room. Reference numeral 6 indicates a main stripping pipe installed horizontally on the bottom side of the cargo oil tank 2; reference numeral 7 indicates a stripping branch pipe having a horizontal portion branching from the main stripping pipe 6;
9 is a bell mouth provided at the tip of the stripping branch pipe 7; 9 is a stripping stop valve provided at the proximal end side of the stripping branch pipe 7; 10
is a dry-up detection device installed in the center of the stripping branch pipe 7 between the stripping stop valve 9 and the bell mouth 8.

The dry-up detection device 10 consists of a float chamber 11 and a valve chamber 12. Inside the float chamber 11 is a float 1 that detects the oil level in the cargo oil tank 2.
3 is disposed within the valve chamber 12, and a hydraulic switching valve 14 that is turned on and off by the movement of the float 13 is disposed.

The conventional dry-up detection operation is configured as described above. For example, at the end of unloading or during tank cleaning, the stripping stop valve 9 is opened and the float chamber 11 of the dry-up detection device 10 is opened.
The float 13 inside is floated by oil and is located at the upper part of the float chamber 11, the hydraulic switching valve 14 is turned off, and a pump (not shown) in the pump chamber 3 is driven to perform stripping. At the final stage of stripping, when almost no oil passes through the stripping branch pipe 7, the float 13 in the float chamber 11 lowers, and the oil level drops to near the opening surface of the bell mouth 8. When the float 13 moves downward, the valve chamber 12 drops due to the downward movement of the float 13.
The hydraulic switching valve 14 inside turns on and detects that there is no liquid level, that is, detects whether the bottom of the cargo oil tank is dry or not, and issues a detection signal, and this detection signal is sent to the cargo handling control room 5. In response to this detection signal, the cargo handling control room 5 takes appropriate measures such as closing the stripping stop valve 9.

[Problem that the invention seeks to solve]

In the conventional dry-up detection device as described above, the oil sucked up from the bell mouth 8 is temporarily stored in the float chamber 11, and the float 13 is moved up and down depending on the amount of the stored oil to determine whether there is a liquid level or to complete stripping. It is designed to detect whether the cargo oil is present or not, and does not directly detect the presence or absence of the liquid level. Therefore, if the viscosity of the cargo oil is high,
There is a possibility that the oil accumulated in the bell mouth 8 will harden and the float 13 will not work.
When the liquid level is near , the bell mouth 8 sucks air together with oil due to the fluctuation of the liquid level, and the float 13 lowers, causing the hydraulic switching valve 1
There was a problem in that it was not always possible to accurately detect the completion of stripping due to erroneous operation of 4.

This invention was made to solve these problems, and is a dry-up detection device that can accurately detect the completion of stripping and also automatically control the rotation of the pump in the pump chamber and the opening and closing of the discharge valve. The purpose is to obtain.

[Means for solving problems]

The dry-up detection device according to the present invention is provided with first and second optical fiber sensors for detecting the presence or absence of a liquid level at the front bottom and rear bottom of a cargo oil tank of a tanker where trim is set, respectively, and When the fiber sensor detects that there is no liquid level in the tanker trim state, it reduces the rotation speed of the turbine that drives the pump installed in the stripping main pipe connected to the cargo oil tank, and throttles the discharge valve. The control circuit is configured to control the turbine to stop when the two-optical fiber sensor detects that there is no liquid level.

[Effect]

When the first optical fiber sensor installed at the front bottom of the cargo oil tank detects that there is no liquid level in the tanker trim state, the control circuit receives a detection signal from the optical fiber sensor. The rotational speed of the turbine that drives the pump is reduced and the discharge valve is throttled to ensure that there is no liquid level when the second optical fiber sensor installed at the rear bottom of the cargo oil tank detects the presence or absence of liquid level when the tanker is trimmed. When detected, the control circuit receives the detection signal from the optical fiber sensor and controls the turbine to stop.

〔Example〕

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

In the figure, 1 is a tanker, 2 is a cargo oil tank,
6 is a stripping branch pipe; 7 is a stripping branch pipe connected to the main stripping pipe 6 and whose tip side is disposed inside the cargo oil tank 2; 8 is a bell mouth provided at the tip of the stripping branch pipe 7;
9 is a stripping stop valve provided on the proximal end side of the stripping branch pipe 7; 16 is a pump provided in the stripping main pipe 6; 17 is the pump 1;
18 is a discharge valve provided in the stripping branch pipe 6.

20 is a first optical fiber sensor provided at the front bottom of the cargo oil tank 2 to detect the presence or absence of an oil level; 21 is a first optical fiber sensor provided at the rear bottom of the cargo oil tank 2 to detect the presence or absence of an oil level. A second optical fiber sensor 22 is connected to these optical fiber sensors 2.
This is a control circuit which controls the rotational speed of the turbine 17, the opening/closing of the discharge valve 18, and the opening/closing of the stripping stop valve 9 in response to liquid level detection signals of 0 and 21. 2
3 is a stuttering detection circuit that detects stuttering of tanker 1;
24 is a ship's trim calculation circuit that calculates the optimal trim value for tanker 1 from the tanker's stasis and tank length, and 25 is a trim correction unit that corrects tanker 1 to the optimal trim based on the trim value of the ship's trim calculation circuit. The trim corrected by the trim correction section is sent to the control circuit 22. Specifically, the trim correction by the trim correction unit 25 is performed by pouring and discharging ballast using a ballast pump.

FIG. 2 is a block diagram of a control circuit that controls the rotation speed of the turbine and the opening and closing of the discharge valve. In the figure, 30 is a first input circuit connected to the first optical fiber sensor 20, 31 is a second input circuit connected to the second optical fiber sensor 21, 32
A discharge valve control circuit is connected to the first input circuit 30 and controls the opening and closing of the discharge valve 18 based on the electrical signal. A discharge valve control circuit 33 is connected to the first and second input circuits 30 and 31 and controls the opening and closing of the discharge valve 18 based on the electric signal. Turbine 1 by signal
This is a steam valve control circuit that controls the opening and closing of the steam valve 34 of No. 7. Therefore, the control circuit 22 is connected to the input circuit 30,
31, discharge valve control circuit 32 and steam valve control circuit 3
It will consist of 3.

3 and 4 are diagrams showing the configuration of the optical fiber sensor. Optical fiber sensor 20, 21
Both have the same configuration, with two optical fibers 4
0, 40, a sensor section 41 formed into a spherical shape by arranging two optical fibers 40, 40 and heat-sealing their tips, and a light emitting diode provided at the end of one optical fiber 40. Light emitting element 42
, a phototransistor light-receiving element 43 provided at the end of another optical fiber 40, and a display circuit 44 connected to the light-receiving element 43.

The liquid level detection principle of the optical fiber sensors 20 and 21 is that light emitted from the light emitting element 42 is sent to the sensor section 41 through one optical fiber 40, and some of the light is transmitted through the spherical surface of the sensor section 41. However, the remaining light is reflected, but when air comes into contact with the sensor part 41, the transmittance of light at the spherical part becomes lower than in the case of oil, and the amount of reflection increases. You can tell whether you have come in contact with

Light receiving element 43 of optical fiber sensor 20, 21
is connected to the control circuit 22 in FIG.

When performing stripping with the dry-up detection device configured as described above, it is first necessary to set the optimum trim for causing the tanker 1 to perform stripping. To set this trim, the stuttering detection circuit 23 detects the stuttering of the tanker 1 before entering the stripping state, and the ship's trim calculation circuit 24 calculates the optimal trim value from the detected stuttering value and the length of the tanker, and then corrects the trim. Part 25
This is done by correcting the tanker 1 to the optimum trim based on the trim value calculated by the ship's trim calculation circuit 24. This is because when the optimal stripping is not set, for example when the difference in oil level between the front and rear parts of the cargo oil tank 2 is too small, the stripping oil will not be sucked in sufficiently. .

Next, to explain the case where the tanker 1 is in the optimal trim state and the cargo oil tank 2 is stripped, the stripping stop valve 9 of the stripping branch pipe 7 connected to the cargo oil tank 2 is
The discharge valve 18 is opened, the turbine 17 is rotated, the pump 16 is operated, and oil suction from the bell mouth 8 begins. The liquid level of the oil in the cargo oil tank 2 gradually decreases due to suction from the bell mouth 8, and air first comes into contact with the sensor section 31 of the first optical fiber sensor 20 provided at the front bottom of the cargo oil tank 2. Then, the optical fiber sensor 20 detects that there is no liquid level. Then,
The liquid level detection signal of the optical fiber sensor 20 is sent to the control circuit 22, and the control circuit 22
The steam valve 34 of the turbine 17 driving the turbine 17 is throttled to reduce the rotation speed, and the discharge valve 1 is opened.
Control to narrow down 8. To explain this in detail based on FIG. 2, the first optical fiber sensor 2
A liquid level detection signal of 0 is sent to a first input circuit 30 of the control circuit 22, and from that input circuit 30 is sent to a discharge valve control circuit 32 and a steam valve control circuit 33. The steam valve control circuit 33 controls the steam valve 34 of the turbine 17 to reduce the rotation speed of the turbine 17, and the discharge valve control circuit 32 controls the discharge valve 18 to throttle it. In this state, stripping is continued, and the oil level in the cargo oil tank 2 further decreases, causing the sensor section 31 of the second optical fiber sensor 21 provided at the rear bottom of the cargo oil tank 2 to drop. When exposed to air, the optical fiber sensor 21 detects that there is no liquid level. Then, the liquid level detection signal of the optical fiber sensor 21 is sent to the control circuit 22, and the control circuit 22 controls the rotation of the turbine 17 that drives the pump 16 to stop.
6 is stopped and stripping is completed.

That is, the liquid level detection signal of the second optical fiber sensor 21 is sent to the second input circuit 31 of the control circuit 22, and from the input circuit 31 to the steam valve control circuit 33.
sent to. At this time, the liquid level detection signal of the first optical fiber sensor 20 is also sent to the steam valve control circuit 33 via the input circuit 30, and the liquid level detection signal of the second optical fiber sensor 21 is sent to the steam valve control circuit 33. 33, the steam valve control circuit 33 controls the steam valve 34 of the turbine 17 to be completely throttled, thereby stopping the rotation of the turbine 17. Therefore,
Operation of the pump 16 is stopped and stripping is completed.

〔Effect of the invention〕

As explained above, the present invention has a first system for detecting the presence or absence of a liquid level, which is disposed at the front bottom and rear bottom of a cargo oil tank of a tanker where trim is to be set.
and the second optical fiber sensor, when the first optical fiber sensor at the front bottom of the cargo oil tank detects that there is no liquid level in the tanker trim state, the control circuit receives a liquid level detection signal from the optical fiber sensor. The system reduces the rotational speed of the turbine that drives the pump that sucks oil in the cargo oil tank and throttles the discharge valve, and the second optical fiber sensor at the rear bottom of the cargo oil tank detects that there is no liquid level in the tanker trim state. The control circuit receives the detection signal from the optical fiber sensor again and stops the turbine when the cargo oil tank is tilted by trimming the tanker, and each optical fiber sensor directly detects the liquid level. The stripping state can be accurately detected by approaching and separating the fibers from the fiber optic sensor, and the control circuit automatically controls the rotation speed of the pump and the opening/closing of the discharge valve according to the detection by these optical fiber sensors, making the stripping work easier. This has the effect of being done efficiently, smoothly and reliably.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention, FIG. 2 is a block diagram of a control circuit, and FIG. 3 is an explanatory diagram showing the liquid level detection principle of an optical fiber sensor.
Figure 4 is a configuration diagram showing the sensor part of the optical fiber sensor in oil, Figure 5 is a configuration diagram showing the sensor part of the optical fiber sensor in air, and Figure 6 is a conventional dry-up detection method. FIG. 7 is a schematic diagram of a tanker equipped with the device, and FIG. 7 is a diagram of the dry-up detection device. In the figure, 2 is a cargo oil tank, 6 is a stripping main pipe, 16 is a pump, 17 is a turbine, and 18
is a discharge valve, 20 is a first optical fiber sensor, 21
2 is a second optical fiber sensor, and 22 is a control circuit. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1 first and second optical fiber sensors for detecting the presence or absence of a liquid level provided at the front bottom and rear bottom of the cargo oil tank of the tanker where trim is to be set, respectively; When the optical fiber sensor detects that there is no liquid level in the tanker trim state, it reduces the rotation speed of the turbine that drives the pump installed in the stripping pipe connected to the cargo oil tank and throttles the discharge valve. A dry-up detection device comprising: a control circuit that controls the turbine to be stopped when a second optical fiber sensor at the rear bottom of the cargo oil tank detects that there is no liquid level in the tanker trim state.