JP2018095058A - Floating structure and cargo handling method for unloading on floating structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a floating structure in which an installation space for the upward transporting device to transport upward, which prevents the floating structure itself from increasing in size and is easy to maintenance this upward transporting device, and a cargo handling method for unloading, in the floating structure operating the cargo handling works which transport horizontally the cargo discharged from the lower part of the cargo hold and then lift upward it.SOLUTION: The upward transporting device 32 to lift upward the cargo has the screw 32aa and the casing 32ab housing the screw 32aa, and arranges the bearing portion 32ad of the rotary shaft 32ac to rotate the screw 32aa and the driving mechanism 32ae to drive rotationally the rotary shaft 32ac outside the casing 32ab, and is composed of the screw conveyor 32a configuring the inlet direction A and outlet direction B of the cargo in the casing 32ab in the direction perpendicular to or direction intersecting with the rotary shaft 32ac.SELECTED DRAWING: Figure 1

Description

  The present invention carries or stores cargo such as bulk cargo and flammable gas hydrate and transports the cargo horizontally from the bottom of the cargo hold and then transports it on the upper deck, The present invention relates to a floating structure such as an FPSO (floating type offshore oil / gas production storage and loading facility) that hydrates produced gas, and a method for lifting and unloading the floating structure.

  For cargo ships that carry bulk cargo, combustible gas hydrates, and other cargo, drop the cargo into the bottom of the cargo hold and transport it to the front or rear of the hull with the horizontal lower horizontal transport device provided at the bottom. Then, the cargo is transported on the upper deck by the upward transport device, and further, the cargo is transported to the land-side lifting and handling device, thereby performing the cargo handling (see, for example, Patent Document 1).

  The gas hydrate carrier ship having such a configuration is, for example, a gas hydrate carrier ship 1X having a structure as shown in FIG. 6. The cargo is transported to the upward conveying device 32 on the bow portion 2 side by the partial horizontal conveying device 31, conveyed to the overhang conveying device 34 on the upper deck 4 by the upward conveying device 32, The overhanging conveying device 34 conveys the material to an unloading equipment (not shown).

  On the other hand, in loading / unloading, cargo supplied from an onshore loading / unloading facility (not shown) is distributed from the loading overhanging device 41 to each cargo hold 21 via the upper horizontal transfer device 42 for loading. It is dropped into the cargo hold 21 from the cargo supply port 43 at the upper central portion of the cargo.

  Examples of the upward conveying device 32 include a vertical or diagonally up and down screw conveyor, a belt conveyor, a bucket conveyor, an air transport pipe, and the like, but a vertical belt conveyor (see, for example, Patent Document 2) or a continuous bucket conveyor ( For example, Patent Document 3) has a problem that the space area for installing the apparatus becomes large, and the cargo ship itself is enlarged.

  Therefore, this upward conveying device can be installed in a narrow space area, and in addition, when conveying cargo such as flammable gas hydrate, it is not only possible to take an explosion-proof measure against the generated flammable gas, It is desired that maintenance is possible without performing complicated operations such as gas replacement.

  On the other hand, a screw conveyor device is provided in the riser pipe in order to convey particles as a vertical conveying device in which the space area as the installation place may be relatively narrow, and the screw conveyor device is provided with a central length in the pipe. A ship handling cargo handling device has been proposed in which spiral screw fins arranged in a direction are rotated by a rotary drive motor to convey particles upward (see, for example, Patent Document 4).

  In the case of the screw conveyor device adopted in this ship delivery cargo handling device, frequent maintenance is unnecessary because there is no intermediate bearing, but since the bearings supporting the screws at both ends are contained in the screw casing, There is a problem that the screw casing needs to be opened for maintenance.

  When the combustible gas hydrate is transported by this screw conveyor device, since the combustible gas is filled in the screw casing, it is conceivable to provide a bearing in the screw casing for the purpose of improving the sealing performance. In this case, when maintaining the screw bearings in the screw casing, it is necessary to discharge all the cargo and the gas attached to the cargo from the screw casing and replace it with air. There is a problem that it is very troublesome and time consuming.

JP 2013-136371 A Japanese Patent Laid-Open No. 11-301823 JP 2007-320762 A Japanese Patent Laying-Open No. 2015-48186

  The present invention has been made in view of the above-described situation, and the object thereof is to provide a floating structure that performs a cargo handling operation in which cargo discharged from the lower part of a cargo hold is transported horizontally and then transported upward. The installation space area of the upward conveyance device for conveyance in the direction is small, the increase in size of the floating structure itself can be suppressed, and maintenance of the upward conveyance device is facilitated. It is an object of the present invention to provide a floating structure that can use a low-cost material that may be relatively low in durability and can reduce the cost, and a method for lifting and handling the floating structure.

  In order to achieve the above object, the floating structure of the present invention is a floating structure that performs a cargo handling operation in which the cargo discharged from the lower part of the cargo hold is transported horizontally and then transported upward. An upward conveying device for conveying in the direction is constituted by a screw conveyor, and the screw conveyor is constituted by having a screw and a casing for accommodating the screw, and a bearing portion of a rotating shaft for rotating the screw; A drive mechanism for rotating the rotating shaft is disposed outside the casing, and the cargo inlet direction and outlet direction in the casing are configured to be perpendicular to or intersecting the rotating shaft. And

  According to this structure, since the upward conveyance apparatus is comprised with the screw conveyor which does not take a comparatively space, the installation space area | region of an upward conveyance apparatus becomes small, and the enlargement of floating structure itself can be suppressed. In addition, since this screw conveyor is formed by a screw conveyor in which the bearings and drive mechanism that require maintenance are provided outside the casing, there is no need to disassemble the casing during maintenance, and maintenance is greatly simplified. The

  In the above floating structure, the cargo hold is formed in a cylindrical shape, and an installation space area of the upward conveying device is set between the side wall plate of the cargo hold and the ship side outer plate or two adjacent ones. If it is provided between the side wall plate of the cargo hold and the ship side outer plate, this configuration makes it unnecessary to lengthen the hull in the front-rear direction in order to provide an installation space region for the upward conveying device, and a floating structure The increase in size of the object itself can be suppressed.

  In the floating structure described above, when the screw conveyor is provided with a plurality of the upward conveying devices arranged in the vertical direction, this configuration allows a single long screw conveyor to convey cargo for a high distance. As compared with the above, by transporting cargo with a plurality of relatively short screw conveyors, the strength of each screw can be easily maintained, and each screw conveyor can be configured compactly. In addition, the size of each driving device can be easily accommodated within a range where it can be easily implemented.

  In the above floating structure, when a sealing mechanism having airtightness is provided in a portion where the rotating shaft passes through the casing, even when the gas hydrate generating flammable gas is conveyed by the sealing mechanism, It can be safely transported while maintaining airtightness.

  In the above floating structure, when the drainage mechanism is provided in the vicinity of the portion where the rotating shaft passes through the casing, the drainage mechanism includes water or cargo generated by the decomposition of the gas hydrate. Water can be separated and drained. In addition, when the gas in a casing turns into a combustible gas, it is desirable for this drainage mechanism to have airtight structures, such as a seal | sticker with a water | moisture content, so that the inside gas may not contact external air.

  In the above floating structure, when the floating structure is any one of a bulk cargo ship, a gas hydrate carrier ship, and an offshore gas hydrate production facility, the above effects can be more effectively exhibited.

  The floating structure lifting and unloading method for achieving the above-mentioned object is a floating structure lifting and unloading method that performs the upward loading after the cargo discharged from the lower part of the cargo hold is transported horizontally. And a casing that accommodates the screw, a bearing portion of a rotating shaft that rotates the screw, and a drive mechanism that rotationally drives the rotating shaft are disposed outside the casing, and the casing The cargo is transported in the upward direction by using an upward transport device comprising a screw conveyor in which the cargo inlet direction and the outlet direction are perpendicular to or intersecting the rotation axis. It is. According to this method, the installation space area of the upward conveyance device for the upward conveyance is small, and maintenance of the upward conveyance device is facilitated.

  According to the floating structure and the floating structure handling method of the present invention, in the floating structure that performs the lifting and unloading that transports the cargo horizontally from the lower part of the cargo hold and then transports it upward, The installation space area of the upward transfer device is small, and the maintenance of the upward transfer device is facilitated, so that it is possible to use a low-cost material that may have relatively low durability for the upward transfer device. As a result, the cost can be reduced.

It is a side view which shows typically the structure of the gas hydrate carrier ship (exemplification as one of the floating structure) of embodiment which concerns on this invention. It is a top view which shows typically the structure of the gas hydrate carrier ship of FIG. It is front sectional drawing which shows typically the structure of the gas hydrate carrier ship of FIG. It is a sectional side view which shows typically the structure of an upward conveyance apparatus. It is a figure which shows typically the structure of the screw conveyor which comprises an upper direction conveying apparatus, and its connection. It is a side view which shows typically the structure of the gas hydrate carrier ship of a prior art. It is a figure which shows typically the structure of the screw conveyor and its connection in the upward conveyance apparatus of a structure different from using with the gas hydrate carrier ship of this invention. It is a figure which shows typically the structure of the screw conveyor in the upward conveyance apparatus of another structure further used with the gas hydrate carrier ship of this invention, and its connection.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a floating structure and an unloading method for a floating structure according to an embodiment of the present invention will be described with reference to the drawings. Examples of the floating structure include a bulk carrier, a gas hydrate carrier, an offshore gas hydrate production facility, and the like. Here, a gas hydrate carrier is described as an example of the floating structure.

  However, the present invention is not limited to this gas hydrate carrier, but can be applied to other bulk carriers, offshore gas hydrate production facilities, and the like. If the floating structure is a bulk carrier, gas hydrate carrier ship, etc., it normally sails, but if it is an offshore gas hydrate production facility, go to the offshore installation site. Only when it is sailing by self-navigation or towing. Further, in the case of cargo that generates flammable gas, airtightness and explosion-proof are necessary. However, in the case of cargo that does not particularly generate gas, airtightness and explosion-proof are not required.

  1 to 4, the gas hydrate carrier 1 according to the embodiment of the present invention includes a bow portion 2, a stern portion 3, an upper deck 4, a ship side outer plate 5, and a ship bottom 6 therebetween. A cargo compartment that is surrounded by the hull and has a cargo hold 21 and an engine room 7 that houses a main engine (not shown) and auxiliary equipment at the rear of the cargo compartment, in other words, on the stern side of the hull. ing. In the configuration of FIGS. 1 to 4, an upper structure 8 including a bridge 8 a, a residential area 8 b, a chimney 8 c, and the like is provided above the engine room 7. These residential areas or bridges may be in the bow. A propeller 9 for navigation is disposed on a propeller shaft extending rearward from the engine room 7, and a rudder 10 is disposed behind the propeller shaft 9.

  In addition, a cargo hold 21 is disposed on the ship bottom 6 in the cargo compartment ahead of the engine room 7 in order to load granular or pellet-like gas hydrates in bulk. In the configuration of FIGS. 1 and 2, four cargo holds 21 are arranged in a line in the longitudinal direction of the hull (from the front, the first cargo hold, the second cargo hold, the third cargo hold, and the fourth cargo hold). ) Are provided side by side.

  The shape of the cargo hold 21 is preferably a cylindrical shape that is easy to spread and collect cargo by a swivel conveying device (not shown), but the cylindrical shape has a higher conformity to the hull shape and is advantageous in terms of volumetric efficiency, A polygonal cylindrical shape may be used. In addition, as shown in FIG. 3, the bottom plate 21a of the cargo hold 21 is provided on the ship bottom 6, and is provided with the double bottom 6a. That is, the cargo hold 21 is surrounded by the bottom plate 21a, the side wall plate 21b, and the ceiling plate 21c.

  As shown in FIGS. 1 to 4, the gas hydrate carrier 1 is discharged from the lower part of the cargo hold 21 as a lifting handling device that transports the cargo from the cargo hold 21 to a land handling facility (not shown). The lower horizontal transport device 31 that transports the received cargo horizontally, and the lower horizontal transport device 31 transports the cargo transported between the adjacent cargo holds 21 from the approximate center position of the cargo hold 21 upward. Upward conveying device 32, upper horizontal conveying device 33 that conveys the cargo conveyed above upper deck 4 by upper conveying device 32 in the horizontal direction, and the unloading equipment ( An overhanging conveying device 34 as a horizontal conveying device for landing is provided.

  The lower horizontal transfer device 31 is composed of a horizontal screw conveyor, a belt conveyor, an air transport pipe, and the like, and is disposed in the double bottom 6 a on the lower side of the cargo hold 21. In this embodiment, the first cargo hold 21 in the front row is arranged to convey cargo to the rear side of the hull, and the other second to fourth cargo holds 21 are arranged to convey cargo to the front side of the hull. .

  And as shown in FIG. 5, the upward conveyance apparatus 32 is comprised with the screw conveyor 32a which has screw 32aa and casing 32ab which accommodates this screw 32aa. Further, a bearing portion 32ad of the rotation shaft 32ac that rotates the screw 32aa and a drive mechanism 32ae that rotates the rotation shaft 32ac are disposed outside the casing 32ab. In addition, the cargo entrance direction A and the exit direction B in the casing 32ab are configured to be perpendicular to (or intersect with) the rotation shaft 32ac.

  In the screw conveyor 32a shown in FIG. 5, the screw 32aa rotates together with the rotary shaft 32ac, but may be configured to rotate only by the screw 32aa as shown in FIG. The presence of the rotating shaft 32ac makes it easier to ensure the strength of the screw 32aa, but the absence of the rotating shaft 32ac makes it easier to increase the amount of cargo transported by the screw 32aa.

  According to this configuration, since the upward conveying device 32 is configured by the screw conveyor 32a that does not take up a relatively large space, the installation space area (installation space) of the upward conveying device 32 becomes very small, and the gas hide The enlargement of the rate carrier 1 itself can be suppressed.

  Further, the screw conveyor 32a is formed by the screw conveyor 32a in which the bearing portion 32ad and the drive mechanism 32ae that require maintenance are provided outside the casing 32ab. There is no need to disassemble, and maintenance is significantly easier. In particular, even in the case of cargo that generates combustible gas, it is not necessary to purge the gas in the casing 32ab. In addition, since maintenance can be performed easily, the degree of damage of these parts and mechanisms can be confirmed at all times, so that the screw conveyor 32a can be formed of an inexpensive material with relatively low durability, Cost reduction can be achieved.

  In order to explain the merit of configuring the upward conveying device 32 with a screw conveyor 32a as shown in FIG. 5, the upper conveyor device 32 is configured with screw conveyors 32Xa and 32Ya having different configurations as shown in FIGS. The direction transfer devices 32X and 32Y will be described. The difference between the screw conveyor 32Xa in FIG. 7 and the screw conveyor 32Ya in FIG. 8 is only a difference in whether the screw 32aa rotates with the rotating shaft 32ac or only with the screw 32aa.

  7 and FIG. 8, the upper conveyors 32X and 32Y are configured by connecting screw conveyors 32Xa and 32Ya in series in the vertical direction. In the upper screw conveyors 32Xa and 32Ya, the cargo entrance direction A is rotated. In the same vertical direction as the axial direction of the shaft 32ac, the outlet direction B is a horizontal direction perpendicular to the axial direction of the rotary shaft 32ac. Further, in the lower screw conveyor 32Xa, the cargo entrance direction A and the exit direction B are in the same vertical direction as the axial direction of the rotary shaft 32ac.

  Further, the bearing portions 32ad of the rotary shaft 32ac shown in FIGS. 7 and 8 are provided on the upper and lower sides of the cargo outlet or the lower side of the cargo outlet in the upper screw conveyors 32Xa and 32Ya. The lower screw conveyors 32Xa and 32Ya are provided at the uppermost part and the lowermost part. In the uppermost portion and the lowermost portion, the bearing portion 32ad is disposed in the casing 32ab so that cargo can pass therethrough.

  Therefore, when the maintenance of the bearing portion 32ad of the rotary shaft 32ac of the upper and lower screw conveyors 32Xa and 32Ya shown in FIGS. 7 and 8 is required, the casing 32ab needs to be opened, and the combustible gas and air must be replaced. Therefore, the maintenance work becomes complicated. Furthermore, since it is necessary to transmit the driving force from the driving device 32ae to the rotation shaft 32ac by the transmission shaft 32ah, a power transmission mechanism such as a gear or a belt is required between the rotation shaft 32ac and the transmission shaft 32ah. This also complicates the maintenance work.

  Further, in the gas hydrate carrier 1 according to the embodiment of the present invention, the installation space region of the upward conveying device 32 is set between the side wall plate 21b of the cargo hold 21 and the ship side outer plate 5 or two adjacent cargoes. It is provided between the side wall plate 21 b of the warehouse 21 and the ship side outer plate 5. With this configuration, it is not necessary to lengthen the hull in the front-rear direction in order to provide an installation space area for the upward transfer device 32, and the increase in size of the gas hydrate carrier 1 itself can be suppressed. For example, a ship with a total length of about 285 m can be reduced by about 10 m to 20 m compared to a case where a vertical belt conveyor or a continuous bucket system is employed.

  Moreover, as shown in FIGS. 3-5, when it comprises with the screw conveyor 32a which has arrange | positioned the upper direction conveying apparatus 32 in the up-down direction (three in FIG.3 and FIG.4), by this structure, Compared with the case where a single long screw conveyor 32a conveys cargo over a high distance, by conveying the cargo with a plurality of relatively short screw conveyors 32a, each screw conveyor 32a can be made compact. The strength can be easily maintained, and the size of each driving device 32ae can be easily accommodated within a realizable range. In addition, by connecting a plurality of screw conveyors 32a, the degree of freedom of the transport route is increased. From the bottom to the top, in other words, from the bottom 6 to the upper deck 4, even if there is no installation space, the vertical space portion Can be transported to the upper side of the upper deck 4 by detouring several of them.

  Furthermore, when the sealing mechanism 32af having airtightness is provided in a portion where the rotary shaft 32ac passes through the casing 32ab, the sealing mechanism 32af provides airtightness even when transporting a gas hydrate that generates combustible gas. It can be held and transported safely.

  Further, when the drainage mechanism 32ag is provided in the vicinity of the portion where the rotating shaft 32ac passes through the casing 32ab, the drainage mechanism 32ag separates moisture generated by decomposition of gas hydrate and moisture contained in the cargo. And drain. In addition, when the gas in casing 32ab turns into a combustible gas, it is desirable for this drainage mechanism 32ag to have the airtight structure by a water column etc. so that the gas inside may not contact external air.

  Similarly to the lower horizontal conveyance device 31, the upper horizontal conveyance device 33 is composed of a horizontal screw conveyor, a belt conveyor, an air transportation pipe, and the like, and is disposed on the upper deck 4. In the gas hydrate carrier 1 of this embodiment, the cargo in the first cargo hold 21 and the third cargo hold 21 is transferred to the overhanging transfer device 34 provided at the front of the first cargo hold 21 in the front row. In the left and right rows of the port side upper horizontal transport device 33 and the starboard side upper horizontal transport device 33 that transports the cargo of the second cargo hold 21 and the fourth cargo hold 21 to the same overhanging transport device 34 It is configured.

  The overhang conveying device 34 is a device for unloading cargo to the land side by connecting to an unloading and unloading device (not shown). It is provided so as to be able to project outward from 5. As a result, it is accommodated inside the ship side during navigation, and overhangs outside the ship side during cargo handling, and is connected to the landing handling equipment.

  Further, as a cargo handling facility, a cargo overhanging device 41, a cargo upper horizontal conveying device 42, and a cargo cargo supply port 43 provided at the center of the upper portion of each cargo hold 21 are provided. That is, the cargo overhanging device 41 is configured to receive cargo from the land-side cargo handling device, and the cargo conveyed from the cargo overhanging device 41 is supplied to the cargo cargo supply port 43 at the upper part of the cargo hold 21. An upper horizontal transfer device 42 for loading is provided.

  The upper horizontal transfer device 42 for loading is configured by a horizontal screw conveyor, a belt conveyor, a bucket conveyor, an air transport pipe, and the like. Further, the upper horizontal transfer device 42 for loading is provided on the upper side of the upper deck 4 or on the lower side of the upper deck 4 (in the configuration of FIGS. 1 to 4, on the upper side of the upper deck 4). The configuration provided below the upper deck 4 can easily cover the periphery with an inert gas, but the upper deck 4 tends to be high. On the other hand, in the structure arrange | positioned above the upper deck 4, the airtight structure which covers the upper horizontal conveyance apparatus 42 for loads is required.

  Further, in the case where the upper horizontal transfer device 42 for loading is provided, as shown in FIG. 2, the loading overhanging device 41 is configured to be connectable to the land-side loading and unloading device 41. The cargo can be received and supplied to the upper horizontal transfer device 42 for loading. Accordingly, it is possible to avoid the land-side loading / unloading apparatus being deployed in the hull side rather than the ship side, and the possibility that the land-side loading / unloading apparatus collides with the hull and damages the hull can be eliminated.

  By these devices, the cargo supplied from the land loading / unloading facility is transported in the horizontal direction by the loading overhanging device 41 and the loading upper horizontal conveying device 42 and distributed to the loaded cargo supply port 43 of each cargo hold 21. Then, the distributed cargo is dropped into the cargo holds 21 from the cargo supply port 43 to load the cargo into the cargo holds 21.

  With regard to this cargo handling facility, when cargo that generates flammable gas is loaded, the cargo transportation route at the cargo overhanging device 41, the cargo upper horizontal conveying device 42, and the cargo cargo supply port 43 is externally set. And is filled with an inert gas as necessary.

  Next, a method for lifting and handling a gas hydrate carrier (floating structure) according to an embodiment of the present invention will be described. This lifting / unloading method is a lifting / unloading method for a gas hydrate carrier that performs a lifting / unloading operation in which the cargo discharged from the lower part of the cargo hold 21 is horizontally transported and then transported upward. In this lifting and unloading method, the screw conveyor 32a is constituted by a screw conveyor 32a, and the screw conveyor 32a is constituted by having a screw 32aa and a casing 32ab for accommodating the screw 32aa, and a bearing of a rotating shaft 32ac for rotating the screw 32aa The part 32ad and the drive mechanism 32ae for rotating the rotary shaft 32ac are arranged outside the casing 32ab, and the cargo inlet direction A and the outlet direction B in the casing 32ab are perpendicular to or intersecting the rotary shaft 32ac. This is a method of transporting cargo in the upward direction by using the configured upward transport device 32.

  According to the lifting and unloading method of the gas hydrate carrier 1 and the gas hydrate carrier having the above-described configuration, the gas hydrate that performs the lifting and unloading of the cargo discharged from the lower part of the cargo hold 21 and then transported upward. In the transport ship 1, the installation space area of the upward transfer device 32 for the upward transfer is small, and the maintenance of the upward transfer device 32 is facilitated, whereby the upward transfer device 32 has durability. Costs can be reduced because low-cost materials that may be relatively low can be used.

1, 1X Gas hydrate carrier (floating structure)
4 Upper deck 5 Ship side outer plate 6 Ship bottom 21 Cargo hold 21a Cargo hold bottom plate 21b Cargo hold side wall plate 21c Cargo hold ceiling plate 31 Lower horizontal transfer device 32, 32X, 32Y Upper transfer device 33 Upper horizontal transfer device 34 Overhang Conveying devices 32a, 32Xa, 32Ya Screw conveyor 32aa Screw 32ab Casing 32ac Rotating shaft 32ad Bearing portion 32ae Drive mechanism 32af Sealing mechanism 32ag Drainage mechanism 32ah Transmission shaft 32ai Transmission shaft bearing portion 41 Loading overhang device 42 Loading upper horizontal conveying device 43 Cargo supply port A Cargo entrance direction B Cargo exit direction

Claims (7)

  In the floating structure that performs the unloading work that transports the cargo discharged from the lower part of the cargo hold horizontally and then upwards, the upward transport device that transports the cargo upward is constituted by a screw conveyor, and this The screw conveyor is configured to include a screw and a casing that accommodates the screw, and a bearing portion of a rotating shaft that rotates the screw and a drive mechanism that rotationally drives the rotating shaft are disposed outside the casing. And the floating body structure characterized by having comprised the entrance direction and exit direction of the cargo in the said casing to the direction which is perpendicular | vertical or cross | intersects with respect to the said rotating shaft.   The cargo hold is formed in a cylindrical shape, and an installation space area of the upward conveying device is set between a side wall plate of the cargo hold and a ship side outer plate, or two adjacent side walls of the cargo hold. The floating structure according to claim 1, wherein the floating structure is provided between a ship-side outer plate and the ship-side outer plate.   The floating structure according to claim 1 or 2, comprising a plurality of the upward conveying devices arranged in the vertical direction.   The floating structure according to any one of claims 1 to 3, wherein a sealing mechanism having airtightness is provided in a portion where the rotating shaft passes through the casing.   The floating structure according to any one of claims 1 to 4, wherein a drainage mechanism is provided in the vicinity of a portion where the rotating shaft passes through the casing.   The floating structure according to any one of claims 1 to 5, wherein the floating structure is any one of a bulk carrier, a gas hydrate carrier, and an offshore gas hydrate production facility. .   In a method for lifting and unloading a floating structure that performs a lifting and unloading operation in which a cargo discharged from a lower part of a cargo hold is horizontally transported and then transported upward, a screw and a casing that accommodates the screw, and the screw A rotating shaft bearing for rotating the rotating shaft and a driving mechanism for rotating the rotating shaft are disposed outside the casing, and the cargo inlet direction and outlet direction in the casing are perpendicular to or intersecting the rotating shaft. A method for unloading a floating structure, characterized in that cargo is transported upward using an upward transport device configured by a screw conveyor as a direction.

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