JP5038179B2 - Ship bottom reference target - Google Patents

Description

  The present invention relates to a radio wave level meter that can measure the liquid level of a liquid cargo more accurately in order to determine the appropriate time to start a stripping operation when unloading the liquid cargo loaded on a ship. It relates to a ship bottom reference target.

  Liquid cargo carriers such as tankers are equipped with a plurality of different types of pumps for switching according to the liquid level of the liquid cargo for use in unloading the liquid cargo. A spiral pump, a submerged pump, a screw pump, or the like is used from the start of unloading (for example, when fully loaded) to a predetermined liquid level. These pumps will not be able to perform sufficient discharge (discharge toward the storage tank on the land side) when the liquid level drops, so at the stage where the liquid cargo has been unloaded to some extent The work is carried out while balancing the flow rate and the suction force of the pump while narrowing the valve on the discharge side and decreasing the rotation speed of the pump. When the liquid level is further lowered, unloading using these main pumps becomes difficult, so switching to unloading work using a stripping pump such as a reciprocating pump or a vacuum pump. The unloading operation using the stripping pump is generally called “stripping operation (dripping operation)”.

  All loaded liquid cargo must be unloaded at the transport destination. If the above stripping operation is not performed effectively, the amount of liquid cargo left is increased. After the unloading operation, it is necessary to clean up to load the next liquid cargo. Therefore, if the amount of the remaining liquid cargo increases, the amount of liquid cargo discharged to the sea by the cleaning increases. The International Convention on the Prevention of Marine Pollution strictly regulates the discharge of oil and toxic liquid substances from ships, and in order to prevent the discharge of cargo into the sea by tank cleaning as described above, the residue of the cargo is removed by stripping work. Is required to be minimized. As described above, the stripping operation is very important for completely unloading the load requested by the shipper and for complying with the regulations of the Convention.

  In order to perform stripping work effectively, the start time is very important. As described above, since the start time of the stripping operation is determined by the remaining amount of the liquid cargo, it is necessary to more accurately measure the liquid level during the unloading operation.

  There are various types of liquid level gauges that measure the liquid level of liquid cargo loaded in storage tanks. Here, a radio wave type level gauge that measures the liquid level by radio waves will be described as an example. FIG. 9 shows an example in which a conventionally known radio wave level gauge is installed in a storage tank. In FIG. 9, the radio wave level gauge 100 is installed on the deck of the storage tank 20 formed by the vertical bulkhead, the horizontal bulkhead, and the bottom of the ship, and emits radio waves 50 toward the liquid cargo 30. The liquid level is measured by detecting the radio wave reflected and returned by the liquid surface 40.

  In FIG. 9, the radio wave 50 emitted from the radio wave level gauge 100 and the radio wave 51 reflected from the liquid level 40 and the bottom of the storage tank 20 and returning to the radio wave level gauge 100 are shown by straight lines. ing. Further, the liquid level 40 and the bottom surface of the storage tank are also shown as straight lines and are expressed as planes. However, the actual radio wave does not propagate or reflect linearly as shown in the figure, and is not a mirror-like plane that can also linearly show the liquid level 40 and the bottom surface of the storage tank 20. .

  In general, the radio wave emitted from the radio wave level gauge 100 has a radio wave propagating radially within a range of several degrees in the downward direction (approximately 10 degrees), compared to radio waves propagating outside the range. Designed to be strong. Even in actual radio wave level gauges, the liquid level is measured by detecting the reflection of radio waves with strong energy. Therefore, the “high-energy radio wave” propagates substantially linearly toward the liquid level and the bottom of the storage tank, the reflecting surface is in a mirror-like state, and the reflected radio wave is also emitted almost linearly. Even if the liquid level measurement model is described using a propagation model that returns to the radio wave level gauge 100 that is the source, there is no particular doubt.

  That is, when the radio wave propagated in another direction, for example, the radio wave reflected by the wall surface of the storage tank 20 or the liquid level 40 is changed by the fine wave, the radio wave type liquid level is repeatedly reflected in an unexpected direction. Returning to the total 100, such radio waves can be filtered and removed by the signal processing circuit. Therefore, the influence on the measurement of the liquid level is small, without showing those radio waves, only the radio waves directly acting on the measurement are represented linearly, and the liquid level and the bottom surface are represented by a plane like a mirror, The measurement of the liquid level using the radio wave type liquid level gauge 100 will be described.

  As shown in FIG. 9, the storage tank 20 is provided with an ullage stand 36, and an ullage reference point 35 is set as a measurement reference. The maximum reference ullage 31, which is the distance from the ullage reference point 35 to the bottom of the storage tank, is measured in advance at the shipyard when the ship is newly constructed.

  The position (level 33) of the liquid level 40 is measured in advance by calculating the measured ullage 32 from the distance until the radio wave 50 emitted from the radio wave level gauge 100 is reflected back by the liquid level 40 and the antenna offset 34. This can be obtained by subtracting the measured ullage 32 from the maximum reference ullage 31 that has been set. By preparing a conversion table for converting the load amount of the liquid cargo 33 based on the level 33 in advance, the current load amount of the liquid cargo 33 using the radio wave level gauge 100 can be known.

  FIG. 10 shows a functional block diagram of the radio wave type level gauge 100. In FIG. 10, the radio wave level gauge 100 includes an antenna unit 101, a radio unit 102, a power source unit 103, a control unit 104, and a terminal unit 105. The antenna unit 101 emits a measurement radio wave toward the liquid cargo, and receives the radio wave reflected back by the liquid surface 40. The radio unit 102 is a vibrator for a radio wave to be transmitted. The radio unit 102 oscillates based on a signal from the radio control unit 104a, transmits the radio wave from the antenna 101, and receives a radio wave reflected by an object and returned. Compared with the transmitted radio wave, processing for sending the result to the radio control unit 104a is performed. The power supply unit 103 supplies power necessary for the radio wave level gauge 100 to perform a predetermined operation. The control unit 104 includes a wireless control unit 104a, a signal processing unit 104b, and a communication unit 104c. The radio control unit 104a instructs the radio unit 102 to vibrate and receive / transmit radio waves based on the radio wave transmission method and frequency plan. The signal processing unit 104b is a CPU, which processes a signal sent from the wireless control unit 104a and performs an operation for converting a frequency or time difference between a transmitted radio wave and a received radio wave into a distance. The load amount of the liquid cargo 30 is calculated using the distance to the liquid level based on the calculation result of the signal processing unit 104b and the conversion data stored in advance in a storage unit (not shown). The calculation result is output to the terminal unit 105 via the communication unit 104. The terminal unit 105 is a connection terminal for connecting to various devices such as a display device and a device that controls the pump, and connects the various devices and the radio wave level gauge 100 via the connection terminal. It is configured.

  Returning to FIG. The radio wave emitted from the radio wave level gauge 100 is not totally reflected by the liquid level 40, but part of the radio wave is transmitted through the liquid level and propagates in the liquid cargo 30, and the bottom and side portions of the storage tank 20 Reflect by. In particular, when the radio wave 51 reflected by the bottom part returns to the liquid level direction and becomes stronger than the radio wave 50 reflected by the liquid level 40, the signal processing unit 104b determines that the liquid level is present and transmits incorrect information. When the load of liquid cargo 30 is large and the liquid level is high, the radio wave 51 transmitted through the liquid level 40 is attenuated and the energy returning to the liquid level is reduced, so the radio wave 51 is not strong enough to cause a measurement error. When the liquid level 40 is lowered (when the loading amount of the liquid cargo 30 is reduced), the radio wave 51 is less attenuated, and thus returns through the liquid level with higher energy. More priority will be given.

  In order to prevent the spectrum of the radio wave 51 reflected from the bottom of the storage tank as described above from being larger than that of the radio wave for measurement and causing a measurement error, the bottom installed at a predetermined height from the bottom of the storage tank. A reflector is known (see Patent Document 1).

JP 2006-515068 A

  The bottom reflector has a first reflection coefficient when the liquid level of the cargo liquid is higher than the installation position of the bottom reflector, and has a second reflection coefficient when the liquid level is low. The first reflection coefficient is substantially smaller than the second reflection coefficient. By using this, an accurate liquid level can be detected even when the liquid level of the cargo liquid is low.

  However, even if the above bottom reflector is used, it is not possible to accurately calculate the remaining amount of liquid cargo for timely switching to stripping work during unloading work. In general, a liquid cargo ship is provided with a plurality of storage tanks, and in each of the storage tanks, the liquid level is measured using the liquid level gauge as described above. However, the bottom of the storage tank may change depending on the weight of the liquid cargo in the storage tank, the draft condition, or the loading conditions of other storage tanks in the surrounding area due to the sequential change of the liquid level, especially during unloading operations. Sequentially deform. Therefore, since the main dimension of the storage tank 20 changes, the remaining amount of liquid cargo cannot be accurately calculated.

  The deformation | transformation of the storage tank 20 at the time of this unloading operation | work is demonstrated using FIG. FIG. 11A shows a state in which the liquid cargo 30 is loaded on the hull 1 having a plurality of storage tanks 20. The hull 1 has a bow direction on the right side and a stern direction on the left side. The storage tank 20 provided in the hull 1 is formed by dividing the inside of the hull by a vertical partition wall and a horizontal partition wall. When all the storage tanks 20 are full of liquid cargo 30, the ship or upper deck is designed to be substantially parallel to the sea surface 3 (draft). The bottom of the ship has a single (single bottom) or double (double bottom) structure, but in any case, the following description is the same.

  As shown in FIG. 11 (b), the unloading operation at the transportation destination is performed in the tank that is initially unloaded, because the loading amount of the liquid cargo 30 decreases while the draft is still deep. The downward pressure at is lowered, the pressure of seawater applied from the outside becomes larger, and the ship bottom 2 is deformed upward (dented).

  Further, the unloading work proceeds and the tank unloaded in the latter stage of the work has a shallow draft, and the bottom 2 approaches the sea surface 3. Approaches the sea surface 3 and the bottom 2 of the part on which the liquid cargo 30 is loaded is deformed downward (convex) by the pressure of the liquid cargo 30. As already explained, it is very important to accurately grasp the liquid level position of the liquid cargo 30 during the unloading operation. However, as described above, when the ship bottom 2 is deformed, the maximum reference ullage that the radio wave level gauge 100 becomes a reference for calculating the liquid level position changes, so the remaining load capacity of the liquid cargo 30 is accurately determined. It was difficult to grasp.

  In order to correct the measurement result of the radio wave level gauge in consideration of the deformation of the ship bottom 2 as described above, a reference is required in relation to the ship bottom. Therefore, even if the bottom reflector described in Patent Document 1 is used as the “reference point”, the radio wave 51 is not reflected in the liquid cargo 30, so that the function as the reference point is not exhibited. Even if the position goes down and comes out in the air and reflects the radio wave 51, at that time, the time for switching to the stripping work is already missed. Therefore, even in the liquid cargo 30, a reference that can reflect the radio wave 51 to measure its position and transmit a certain amount of radio wave 51 to cause reflection from the bottom. The structure which becomes is required.

  Therefore, the present invention has been made in view of the above problems, and the bottom of the storage tank is deformed in order to properly grasp the switching timing of the pump used when unloading from the liquid storage tank provided in the hull. It is an object of the present invention to provide a ship bottom reference target that can accurately measure the liquid level even in such a case.

The present invention relates to a ship bottom reference that reflects radio waves emitted from a radio wave level gauge installed at the top of the liquid tank toward the bottom of the liquid tank in order to measure the liquid level in the liquid tank installed at the ship bottom. a target, keeping the radio wave reflecting portion for reflecting the radio waves to the electric-wave liquid level gauge, and a radio wave transmission unit to the electric wave transmitted toward the bottom, a predetermined height from the bottom fixed a fixing portion for, have a outer shape of the ship bottom portion reference target is a conical, the radio wave reflecting portion is an inner conical surface of the conical, the radio wave transmitting portion of the inner conical surface one The main feature is that the apex portion of the conical shape is installed toward the bottom portion .

Further, the ship bottom reference target of the present invention is a cone shape, the radio wave reflection portion is a conical inner cone surface, the radio wave transmission portion is a gap formed in a part of the cone surface, The apex part is installed toward the bottom part. The ship bottom portion reference target may be a conical, may be a polygonal cone shape, the inner angle of the vertices in these pyramidal may be a right angle.

  In the present invention, the ship bottom reference target may be a spherical crown. In this case, the radio wave reflecting portion is an inner curved surface of the spherical crown, and the radio wave transmitting portion is one of the curved surfaces of the spherical crown. The outer curved surface part of the curvature center part is installed toward the said bottom part, It is the space | gap part formed in the part, It is characterized by the above-mentioned.

  In the present invention, the ship bottom reference target may be a paraboloid, and in this case, the radio wave reflection portion is an inner surface of the paraboloid shape, and the radio wave transmission portion is one of the paraboloid shapes. It is the space | gap part formed in the part, and the vertex part is installed toward the said bottom part, It is characterized by the above-mentioned.

In the present invention, the radio wave transmission unit included in the vessel bottom part reference target may be a multi-point perforation to be formed on the cone surface and a curved surface or the like in the shape of the.

  According to the present invention, even if the storage tank bottom portion is deformed by the unloading operation, the positional relationship between the reference point and the bottom portion does not change, so an accurate liquid level measurement result can be obtained, and the stripping operation can be performed. By grasping the transition time more appropriately, it is possible to reduce the amount of residual liquid discharged by subsequent tank cleaning.

  Hereinafter, embodiments of a ship bottom reference target according to the present invention will be described with reference to the drawings. In the following explanation, the radio wave emitted from the radio wave level gauge is represented by a straight line, and the liquid level and the bottom surface of the storage tank are represented by a plane. However, as described above, the actual radio wave does not propagate linearly. Also, the liquid level and the bottom are not flat. However, even if the radio wave is expressed in a straight line, the function and effect of the ship bottom reference target according to the present invention are not impaired, and therefore, the radio wave, the liquid level, and the bottom surface are all expressed in a straight line.

  FIG. 1 is a cross-sectional view showing an example in which the ship bottom reference target 10 is installed in the storage tank 20. As shown in FIG. 1, the ship bottom reference target 10 is a structure that is installed at a predetermined height on the bottom of the storage tank 20, and is disposed so as to be positioned directly below the radio wave level gauge 100. The radio wave 50 emitted from the radio wave level gauge 100 is reflected by the liquid level 40 and returns to the radio wave level gauge 100. The liquid level is measured by receiving this radio wave 50, and the load amount of the liquid cargo 30 is calculated. A part of the radio wave passes through the liquid surface 40 and propagates in the liquid cargo 30. Radio waves propagating in the liquid cargo 30 are denoted by reference numerals 51 and 52.

  At the time of completion of the ship equipped with the storage tank 20, the ship bottom reference target 10 measures the distance from the reference point installed on the deck to the tank bottom of the storage tank 20 and sets the maximum reference ullage. The storage tank 20 is installed at a predetermined height (for example, 1 meter) from the bottom of the tank, and the ullage as a reference for the ship bottom reference target 10 is measured. The radio wave 51 passes through the radio wave transmission part provided on the ship bottom reference target 10, is reflected on the tank bottom surface of the storage tank 20, and returns to the liquid surface direction. The radio wave 52 is reflected by the reference ullage by the radio wave reflection part of the ship bottom reference target 10 and returns to the liquid surface direction. As described above, the ship bottom reference target 10 includes a radio wave reflection unit that reflects radio waves toward the radio wave level gauge and a radio wave transmission unit that transmits radio waves toward the tank bottom surface. The radio wave reflector is fixed at a predetermined height from the tank bottom surface of the storage tank 20, and a part of the radio wave is transmitted to obtain radio waves reflected from the tank bottom surface. Even if it is deformed, a reference surface with respect to the liquid surface can be obtained.

Next, an example of the shape of the ship bottom reference target 10 will be described with reference to FIG. The ship bottom portion reference target 10 described here has a conical appearance and is cut along a line parallel to the opening portion to form a void at the apex portion. The air gap 51 allows the radio wave 51 to pass therethrough and prevents the liquid cargo 30 and the cleaning liquid used for cleaning the inside of the storage tank 20 from accumulating, and thus is formed only by cutting the apex portion. It not, for example, can also be formed by providing a hole in a part of the cone surface.

2, vessel bottom portion reference target 10 is a bottom portion of the opening portion circular conical facing the liquid surface direction, is intended to be fixed towards the top side to the bottom side of the storage tank 20. FIG. 2A is a side view of the ship bottom reference target 10. Ship bottom portion reference target 10 as shown in FIG. 2 (a) is formed by a cone surface, the radio wave reflecting portion 11 which reflects the wave 52 (FIG. 1), radio wave consisting of the air gap provided on the top side of the cone surface The radio wave transmission unit 12 transmits the radio wave 51 and the fixing unit 13 fixes the radio wave reflection unit 11 with a predetermined height from the bottom surface of the storage tank. FIG. 2B is a top view of the ship bottom reference target 10. Although the radio wave transmission unit 12 is represented by a circle, the radio wave reflection unit 11 can reflect the radio wave 52 at a predetermined altitude, and the radio wave transmission unit 12 transmits the radio wave 51 and is reflected by the bottom surface of the storage tank. The shape is not limited to this as long as it can return to the liquid level. Since the radio wave transmitting portion 12 is formed, the “top portion” is a virtual vertex.

FIG. 3 is a transparent sectional view of the ship bottom reference target 10. The center position of the ship bottom reference target 10 is indicated by a two-dot chain line. Telecommunications 52 against the cone surface of the radio wave reflecting portion 11 (point A), is reflected by the radio wave liquid level gauge 100 direction from the cone surface of the opposite side (point B). The apex angle of the cone forming the ship bottom reference target 10 is 90 degrees. A vertical line through this vertex O, when the intersection of the propagation path of the radio wave 52 traveling from A to B and C, a point A radio 52 collide, the relationship between the point B of the cone surface of the opposite side by the vertex O Symmetric and AB length corresponds to twice CO (AB = 2 (CO)). That is, regardless of the presence / absence of the radio wave transmitting portion 12, the radio wave 52 propagates a distance equivalent to that reflected by the vertex O and is reflected toward the radio wave level gauge 100.

  Therefore, even if the bottom surface of the storage tank 20 is deformed by setting the length from the bottom surface of the storage tank to the top O to the level of the bottom portion reference target 10 (bottom reference 14), the bottom portion reference target 10 Since the positional relationship between the storage tank 20 and the bottom surface of the storage tank 20 does not change, the radio wave 52 reflected from the ship bottom reference target 10 and the radio wave transmitted through the radio wave transmission part 12 of the ship bottom reference target 10 and reflected by the storage tank bottom surface. 51, or by detecting the radio wave 51 reflected by the bottom surface of the storage tank 20 through the periphery of the ship bottom reference target and measuring each position, the liquid level can be measured more accurately.

  As described above, by using the ship bottom reference target 10, when the liquid cargo 30 is unloaded, it is possible to accurately grasp the remaining load remaining amount of the liquid cargo 30 and determine the appropriate time to start the stripping operation. It becomes like this. Of the radio waves transmitted through the liquid surface 40 and propagating through the liquid cargo 30, the radio wave 52 reflected and returned from the ship bottom reference target has a slightly lower energy than the radio wave reflected from the bottom surface of the storage tank. In addition, it is desirable to configure the ship bottom reference target 10 and maintain the absolute recognition of the bottom of the storage tank 20.

  The ship bottom reference target 10 described above is not limited to a conical shape, but may be of other shapes. Hereinafter, another embodiment of the ship bottom reference target 10 will be described with reference to FIGS. 4 to 8. In the following description, illustration of the fixing portion is omitted. FIG. 4 is an example of a ship bottom reference target having a flat appearance. The ship bottom reference target 10a is a circular plate having a predetermined thickness, the center of which is an air gap, the circumferential part forms a radio wave reflection part 11a, and the air gap part forms a radio wave transmission part 12a. . The radio wave 52 reflected by the radio wave reflection unit 11a is reflected toward the incident direction.

5, appearance is an example of a vessel bottom portion reference target is a polygonal cone shape. FIGS. 5 (a) are external shapes triangular pyramid, inner cone surface a radio wave reflecting portion 11b, the gap portion formed on the top side forms a radio wave transmission section 12b. FIG. 5 (b), the external shape is a polygonal conical, inner cone surface a radio wave reflecting portion 11c, the gap portion formed on the top side forms a radio wave transmission unit 12c.

  6A and 6B are examples of a ship bottom reference target having a spherical crown appearance, in which FIG. 6A is a perspective view, and FIG. 6B is a diagram showing a state where it is installed at the bottom of the storage tank 20. is there. In the ship bottom reference target 10d, the radio wave reflecting portion 11d is an inner curved surface having a spherical crown shape, and the radio wave transmitting portion 12d is a gap formed in the central portion of the curvature of the spherical crown shape. As shown in FIG. 6 (b), the radio wave 52 hitting the radio wave reflecting part 11d of the ship bottom reference target 10d installed at the bottom of a storage tank (not shown) is reflected in the incident direction. The position of the ship bottom reference target 10 can be measured by the radio wave 52.

  7 is an example of a ship bottom reference target having a parabolic appearance. FIG. 7 (a) is a perspective view, and FIG. 7 (b) is a view showing a state where the tank is installed at the bottom of a storage tank. is there. The ship bottom reference target 10e is a void formed by the radio wave reflecting portion 11e on the inner side of a paraboloid and the radio wave transmitting portion 12d formed on the top side of the paraboloid. As shown in FIG. 7B, the radio wave 52 hitting the radio wave reflecting part 11e of the ship bottom reference target 10e installed at the bottom of the storage tank (not shown) is reflected in the incident direction. The position of the ship bottom reference target 10e can be measured by this reflected wave.

  FIG. 8 is an example of a ship bottom reference target whose appearance is a pseudo partial paraboloid, FIG. 8 (a) is a perspective view, and FIG. 8 (b) shows a state where it is installed at the bottom of a storage tank. FIG. The ship bottom reference target 10f is a pseudo partial paraboloid shape in which the outer shape is a pseudo paraboloid by denting a circular flat plate having a gap in the center portion from the periphery into a knuckle shape. The radio wave reflecting portion 11f is a step-like inner side surface, and the radio wave transmitting portion 12f is a gap formed in the central portion. As shown in FIG. 8 (b), the radio wave 52 hitting the radio wave reflecting part 11f of the ship bottom reference target 10f installed at the bottom of the storage tank (not shown) is reflected in the incident direction. The position of the reference target 10d can be measured.

  The ship bottom reference target described above is an example in which a flat plate is processed into various shapes, but is not limited thereto, and the above shape may be formed using punching metal or expanded metal. . In addition, the design can be freely changed without departing from the technical scope described in the claims.

  In addition, the radio wave transmitting portion of the ship bottom reference target according to the present invention can be formed by cutting out a part of the side surface forming each shape, and using a material having a perforated portion as described above. Thus, the perforated part can be used as a radio wave transmitting part.

  The ship bottom reference target according to the present invention may be a flat plate having a predetermined size (area). Such a flat ship bottom reference target is formed by providing a perforated part in a part of the plane to form a radio wave transmission part, and by forming a radio wave reflection part by other parts, Similar effects can be achieved.

  Further, the flat-shaped ship bottom reference target does not have a perforated portion in a part of the plane, and the radio wave 52 reflected from the ship bottom reference target is reflected from the tank bottom and returns as described above. As long as the energy is smaller than that of the radio wave 51, it may be formed with a size satisfying this condition, and the other shapes described above are also obtained by a flat-plate-shaped ship bottom reference target formed with a size satisfying the predetermined condition. The same effect as the ship bottom reference target having

It is sectional drawing which shows the example which installed the ship-bottom part reference target which concerns on this invention in the storage tank. (A) which shows the example whose external shape of the said ship bottom part reference | standard target is a cone is a side view, (b) is a top view. It is a permeation | transmission sectional view which shows the installation aspect of the said ship bottom part reference | standard target. (A) which shows the example whose external shape of the said ship bottom part reference | standard target is a circular flat plate is a perspective view, (b) is a side view. The outer shape of the ship bottom portion reference target is an example having a polygonal pyramidal (a) is a triangular pyramid-shaped perspective view, a perspective view of a hexagonal pyramidal (b). (A) which shows the example whose external shape of the said ship bottom part reference | standard target is a spherical crown shape is a perspective view, (b) is sectional drawing. (A) which shows the example whose external shape of the said ship bottom part reference | standard target is a paraboloid is a perspective view, (b) is sectional drawing. (A) which shows the example whose external shape of the said ship bottom part reference target is a pseudo partial paraboloid, (b) is a perspective view, (b) is sectional drawing. It is sectional drawing which shows the prior art example which installed the radio wave type level gauge in the storage tank. It is a functional block diagram of the conventional radio wave type liquid level gauge. It is an image sectional view of a ship showing change at the time of unloading work and deformation of a tank part bottom.

Explanation of symbols

10 Ship bottom reference target 11 Radio wave reflection part 12 Radio wave transmission part 13 Fixed part

Claims (9)

To measure the liquid level in the liquid tank installed in the ship's bottom, a vessel bottom portion reference target which reflects a radio wave from the radio wave liquid level gauge installed in a liquid tank top is propelled toward the bottom of the liquid tank ,
The radio wave and radio wave reflecting portion for reflecting toward the electric-wave liquid level gauge,
A radio wave transmission unit to the electric wave transmitted toward the bottom,
Have a, a fixing portion for fixing with a predetermined height from the bottom,
The outer shape of the ship bottom reference target is a cone,
The radio wave reflection part is a conical inner conical surface,
The radio wave transmitting part is a gap formed in a part of the inner cone surface,
The apex of the cone is installed toward the bottom,
A ship bottom reference target. The void portion is formed in the apex of the conical, ship bottom portion reference target of claim 1 wherein. The pyramidal is conical, the vessel bottom portion reference target of claim 1 Symbol placement. The pyramidal is polygonal conical, ship bottom portion reference target of claim 1 Symbol placement. The ship bottom reference target according to any one of claims 1 to 4 , wherein an inner angle of the apex of the cone is a right angle. In order to measure the liquid level in the liquid tank installed at the bottom of the ship, it is a ship bottom reference target that reflects radio waves emitted from the radio wave level gauge installed at the top of the liquid tank toward the bottom of the liquid tank. ,
A radio wave reflector that reflects the radio wave toward the radio wave level gauge;
A radio wave transmitting portion that transmits the radio waves toward the bottom;
A fixing portion for fixing the bottom with a predetermined height from the bottom,
The outer shape of the ship bottom reference target is a spherical crown,
The radio wave reflection portion is an inner curved surface of the spherical crown shape,
The radio wave transmission part is a gap formed in a part of the inner curved surface of the spherical crown,
A ship bottom reference target , wherein an outer curved surface portion of the center of curvature of the spherical crown is installed toward the bottom. The void portion is formed in a center of curvature of the ball crown-shaped, vessel bottom portion reference target of claim 6 wherein. In order to measure the liquid level in the liquid tank installed at the bottom of the ship, it is a ship bottom reference target that reflects radio waves emitted from the radio wave level gauge installed at the top of the liquid tank toward the bottom of the liquid tank. ,
A radio wave reflector that reflects the radio wave toward the radio wave level gauge;
A radio wave transmitting portion that transmits the radio waves toward the bottom;
A fixing portion for fixing the bottom with a predetermined height from the bottom,
The outer shape of the ship bottom reference target is a parabolic shape,
The radio wave reflecting portion is an inner surface of the parabolic shape,
The radio wave transmitting portion is a gap formed in a part of the parabolic shape,
The ship bottom reference target , wherein the top of the paraboloid is installed toward the bottom. The void portion is formed in the apex of the parabolic shape, vessel bottom portion reference target according to claim 8.

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