JPH0612130A - Drainage system for ballast water in oil tank - Google Patents

Abstract

PURPOSE:To exert an anticorrosion effect by automatically discharging only the ballast water in an oil tank from a drain nozzle and controlling the level of the ballast water, etc., within the oil tank to a specified range. CONSTITUTION:This drainage system is composed of facilities for drainage composed of galvanic anodes 31 and 32 mounted on the inside face of an oil tank 1, protective current measuring device 4, 4' mounted on the cores 31a, 32a of the anodes 31, 32, a current detector 6, a galvanic anode for anticorrosion 5, a relay circuit 7, a drain nozzle 2, a drain nozzle piping arrangement 2', driving control parts 9, 9', a drain pump 10, a valve 11 and switches 8, 8', etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drainage device for ballast water or the like stored in an oil tank installed on land, in the ocean or underground, or in a slop oil tank of a tanker.

[0002]

2. Description of the Related Art Originally, a small amount of water was mixed in crude oil, and ballast water was also present in the slop oil tank of the tanker. To be done. When the water or ballast water contained in this crude oil is secondarily transported to the refinery together with the crude oil, salt may be precipitated during the refining process in the oil refiner, which may block valves and heat exchangers. Therefore, it is important to drain the water sufficiently in the oil tank. For this reason, a drain pipe for draining water is installed near the bottom plate in the oil tank, and the oil is collected at the bottom of the oil tank by opening and closing the valve installed in this drain pipe and operating and stopping the drain pump. Drains ballast water that is present. However, if drainage is not performed after the boundary between crude oil and ballast water, etc. is reliably detected, the ballast water, etc. may be insufficiently drained, or even crude oil may be discharged together with ballast water, etc. There is also. As a device for detecting the boundary surface between this crude oil and ballast water, there is a portable oil / water field measuring instrument, etc., and a metal having a potential different from that of the metal constituting the oil tank in the electrolyte, for example, an electrode made of a magnesium alloy, is used. Connect the lead wire and measure, connect the end of this lead wire to the negative terminal of the DC ammeter, and also connect the positive terminal of the DC ammeter to the oil tank with the lead wire. It is taken down, the reading value of the DC ammeter is read, and it is judged whether the electrode is in crude oil or ballast water by this reading value, and the depth at that time is measured by the measure. Further, in order to prevent the bottom portion of the oil tank from being corroded by ballast water or the like, a cathodic protection device made of a metal body having galvanic anode characteristics may be attached to the bottom plate of the oil tank. In this case, if the ballast water or the like is almost completely discharged, the galvanic anode body will be covered with crude oil having a high resistivity, and the anticorrosion current generated from the galvanic anode body will be limited and the anticorrosion effect will not be exhibited. There was a problem.

[0003]

Even if the boundary between crude oil and ballast water is detected by the above-mentioned portable oil / water level measuring instrument, etc., the operation of drainage facilities such as valves and pumps can be performed based on this boundary value. Without control, it was inevitable that crude oil would be mixed into the discharged ballast water. Further, as a means for solving the problem that the galvanic anode body attached to the bottom plate of the crude oil tank is covered with crude oil having a high resistivity, the anticorrosion current generated from the galvanic anode body is limited, and the anticorrosion effect cannot be exhibited. As disclosed in Japanese Utility Model Publication No. 3-51335, there is also a method of pouring the electrolyte solution to the lower side of the storage solution inlet / outlet nozzle provided on the side surface of the oil tank so that the galvanic anode body is completely immersed. However, this method has a drawback in that when a large amount of ballast water or the like is added to the electrolytic solution, the anticorrosion range is increased, and the anticorrosion current is insufficient to obtain a sufficient anticorrosion effect.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks of the conventional method, in which a galvanic anode is attached at a predetermined position on the inner surface of an oil tank to form an inner surface of the oil tank. A means for detecting the anticorrosion current flowing through the inner surface of the oil tank and the galvanic anode is provided at the connection with the galvanic anode, and the residual water in the oil tank is automatically discharged from the drain nozzle based on the current value detected by the means. The residual water level is maintained at a predetermined level.

[0005]

[Function] The anticorrosion current flowing through the inner surface of the oil tank and the galvanic anode is detected by the anticorrosion current measuring device provided at the connecting portion between the galvanic anode mounted on the inner surface of the oil tank and the oil tank, and the detected value is detected. Based on this, the drainage facilities are controlled.
That is, when the level of the ballast water separated from the crude oil rises above the installation point of the galvanic anode, the drainage facility is operated by detecting that the anticorrosion current flows by the anticorrosion current measuring instrument, and the level of the ballast water decreases with the above. When the galvanic anode becomes covered with crude oil, it detects that the anticorrosion current stops flowing and stops the operation of the drainage facility.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of a ballast water drainage device in an oil tank showing an embodiment of the present invention, in which a galvanic anode for current measurement is attached to one location on the inner surface of the oil tank. In FIG. 1, a drain nozzle 2 is attached to a lower part of a side surface of an oil tank 1 so as to penetrate through a side surface of the oil tank 1, and zinc, aluminum, magnesium, or these is provided on an inner surface of the oil tank 1 slightly above the drain nozzle 2. The galvanic anode 31 for electric current measurement made of the above alloy is attached. This galvanic anode for current measurement 3
The core metal 31a of No. 1 is provided with the anticorrosion current measuring device 4 composed of a shunt or a hall element for measuring the anticorrosion current, and the anticorrosion current flowing through the core metal 31a of the galvanic anode 31 for current measurement is the anticorrosion current. The current is detected by the current measuring device 4 and input to the current detector 6. The circuit is configured so that the relay circuit 7 is activated when the anticorrosion current input to the current detector 6 matches a preset value. Switches 8 and 8'operated by the relay circuit 7 are incorporated in the circuit between the drive control units 9 and 9'of the drain pump 10 and the valve 11 and the power source 12 'which are installed in the drain nozzle pipe 2'. ing.

FIG. 2 shows another embodiment of the present invention, in which galvanic anodes 31 and 32 for current measurement are attached to upper and lower two positions on the inner surface of the oil tank 1, and further, the oil tank 1
FIG. 3 is a schematic view showing the configuration of a ballast water drainage device in an oil tank in which an anticorrosion galvanic anode 5 is attached to the inner surface of the bottom plate 1 a of FIG. A current measuring galvanic anode 32 having the same material and shape as that of the current measuring galvanic anode 31 is attached to the inner surface of the oil tank 1 at a predetermined position above the current measuring galvanic anode 31. Further, a corrosive current measuring shunt or a corrosive current measuring device 4'consisting of a Hall element is attached to the core metal 32a of the galvanic anode 32 for current measurement, and is attached to the inner surface of the bottom plate 1a of the oil tank 1. Is an anticorrosion galvanic anode 5 at a position lower than the galvanic anode 31 for current measurement.
Is installed. The anticorrosion current flowing through the core metal 31a of the galvanic anode 31 for measuring current and the galvanic anode 32 for measuring current.
The anticorrosion current flowing through the core metal 32a of the
The circuit is configured so that the relay circuit 7 is activated when the anticorrosion current input to the current detector 6 matches the preset value. . The components other than the components described above are the same as those in FIG.

Next, the operation of the ballast water drainage device in the oil tank according to the present invention will be briefly described. In FIG. 1, when seawater is filled in the oil tank 1, a potential difference occurs between the galvanic anode 31 for current measurement and the inner surface of the oil tank 1, and a certain anticorrosion between the galvanic anode 31 for current measurement and the oil tank 1 is performed. An electric current flows. Further, when crude oil containing a small amount of seawater mixed therein is filled in the oil tank 1, the water contact resistivity around the amperometric anode 31 for current measurement becomes high, and the galvanic anode 31 for current measurement and the oil tank 1 are separated from each other. Almost no anti-corrosion current flows through. Therefore, when the anticorrosion current flowing through the core metal 31a of the galvanic anode 31 for current measurement exceeds a value preset in the current detector 6, the switches 8 and 8'are turned on and the anticorrosion current is detected by the current detector 6. When it is less than the set value of, switch 8
And 8'set the current of the current detector 6 so as to be turned off. If the crude oil containing the seawater injected into the oil tank 1 is left to stand, the seawater and the crude oil are separated, and the crude oil accumulates on the top and the seawater accumulates on the bottom. Therefore, when the galvanic anode 31 for current measurement is in a state of being covered with seawater, the switches 8 and 8'are turned on, and the drain pump 1 is activated by the operation of the drive control units 9 and 9 '.
0 operates, the valve 11 is opened, the seawater in the oil tank 1 is discharged from the outlet of the drain nozzle pipe 2 ', and the seawater level in the oil tank 1 is lowered. When the galvanic anode 31 for current measurement comes to be covered with crude oil due to the decrease in seawater level, the switches 8 and 8 ′ are turned off, the drain pump 10 is stopped, and the valve 11 is closed so that the drainage water from the oil tank 1 is discharged. Stop.

In FIG. 2, when seawater is filled in the oil tank 1, a potential difference occurs between the galvanic anodes 31 and 32 for current measurement and the inner surface of the petroleum tank 1, and the galvanic anodes 31 and 32 for current measurement and the petroleum tank 1 are connected. A certain anticorrosion current flows between the two. Further, when crude oil containing a small amount of seawater mixed therein is filled in the oil tank 1, the water contact resistivity around the current measuring galvanic anodes 31 and 32 becomes high, and the current measuring galvanic anodes 31 and 32 and the oil tanks. Almost no anticorrosion current flows between 1 and. Therefore, when the anticorrosion current flowing through the cored bar 32a of the galvanic anode 32 for current measurement exceeds a value preset in the current detector 6, the switches 8 and 8'are turned on, and the galvanic anode 31 for current measurement is turned on. The anticorrosion current flowing through the core metal 31a is the current detector 6
Switch 8 and 8'when the value becomes less than the value preset in
The current of the current detector 6 is set so that is turned off. When crude oil containing seawater is poured into the oil tank 1 and left to stand still, the seawater and the crude oil are separated, the crude oil accumulates at the top and the seawater accumulates at the bottom. When this seawater rises to the galvanic anode 32 for current measurement, the switches 8 and 8'are turned on, and the drive control unit 9 and
Along with the operation of 9 ', the drain pump 10 is operated, the valve 11 is opened, the seawater in the oil tank 1 is discharged from the outlet of the drain nozzle pipe 2', and the seawater level in the oil tank 1 is lowered. When the galvanic anode 31 for current measurement comes to be covered with crude oil as the seawater level decreases, the switches 8 and 8 '
Is turned off, the drain pump 10 is stopped, the valve 11 is closed, and the drainage from the oil tank 1 is stopped.

As is clear from the above description, in the embodiment shown in FIG. 1, when the seawater level rises above the installation point of the galvanic anode 31 for current measurement, drainage is started and the galvanic anode 31 for current measurement is started. When the temperature drops below the installation point, the drainage will be stopped. In the embodiment shown in FIG. 2, drainage is started when the seawater level rises above the installation point of the current measurement galvanic anode 32, and the seawater level drops below the installation point of the current measurement galvanic anode 31. Then the drainage is stopped.

[0011]

As described above, in the ballast water drainage device for an oil tank according to the present invention, a galvanic anode is attached at a predetermined position on the inner surface of the oil tank to prevent corrosion that flows between the inner surface of the oil tank and the galvanic anode. An anticorrosion current measuring device that detects the current is installed at the connection between the inner surface of the oil tank and the galvanic anode, and the operation of the drainage facility is controlled by the detected current value, and only the residual water is discharged without discharging the oil in the oil tank. Is automatically discharged from the drain nozzle. In addition, since the level of ballast water etc. in the oil tank can be controlled within a certain range, the problem that the anticorrosion current is insufficient and the sufficient anticorrosion effect cannot be obtained due to the increase of the anticorrosion range accompanying the increase of ballast water etc. is solved. Therefore, the anticorrosion galvanic anode is covered with crude oil or the like having a high resistivity, and the anticorrosion current generated from the galvanic anode is limited, so that there is no problem that the anticorrosion effect cannot be exhibited.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a ballast water drainage device in an oil tank showing an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a configuration of a ballast water drainage device in an oil tank showing another embodiment of the present invention.

[Explanation of symbols]

 1 Oil tank 1a Oil tank bottom plate 2 Drain nozzle 2'Drain nozzle pipe 31, 32 Current measuring galvanic anode 32a, 32b Current measuring galvanic anode core metal 4, 4'Corrosion protection current measuring instrument 5 Corrosion protection galvanic anode 6 Current Detector 7 Relay circuit 8,8 'Switch 9,9' Drive controller 10 Drain pump 11 Valve 12, 12 'Power supply

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C23F 13/00 8414-4K

Claims (1)

[Claims] 1. A means for attaching a galvanic anode to a predetermined position on the inner surface of an oil tank and detecting means for detecting an anticorrosion current flowing through the inner surface of the oil tank and the galvanic anode is provided at a connecting portion between the inner surface of the oil tank and the galvanic anode. Provided, the operation of the drainage equipment incidental to the oil tank is controlled by comparing the current value detected by the means with a reference value preset in the current detector, and the residual water in the oil tank is automatically discharged from the drain nozzle. A drainage device for ballast water in an oil tank, wherein the level of the residual water is controlled to a predetermined level by draining.