JP4713095B2 - Offshore offloading system - Google Patents

Description

The present invention relates to an offshore offloading system for transporting solid cargo such as pellet solids of natural gas hydrate produced by a natural gas hydrate offshore production facility to a transport ship on the ocean.

  As natural gas resources, it has recently been known that small-scale gas fields are concentrated in Southeast Asia and Oceania. Most of these gas fields are offshore gas fields.

  With regard to the transportation of natural gas, in the conventional technology, the natural gas is liquefied, transferred from an offshore production facility (FSPO: Floating Production Storage Offloading system) to a transport ship called a shuttle, and moved to a port by a transport ship. A method of landing is considered.

  When transporting these liquid cargoes such as LNG, the transport ship is moored to the offshore production facility and offloading the cargo. It employs piping and flexible hoses that also serve as an absorption mechanism. In the case of this pantograph type, the pantograph mechanism is simplified by adopting a swivel as a link connection point.

  As one of these devices, an offloading connection device for forming a pipeline between an offshore production facility and a transport ship has been proposed (see, for example, Patent Document 1).

  However, in this relatively small offshore gas field, an offshore production facility is arranged on the sea surface directly above the gas field, and the natural gas and water are extracted directly from the offshore natural gas at a predetermined pressure and temperature condition. Safety, stability, and transport efficiency can be improved by using a hydrate (NGH: Natural Gas Hydrate), which is a stable sorbet-like hydrate as a solid, and handling the pellet as a solid.

  The method of generating and transporting natural gas hydrates offshore by directly hydrating and shipping natural gas offshore, compared to the method of transporting natural gas to land and generating natural gas hydrates on land. Therefore, it is expected that transportation costs can be reduced by about 20%. In this marine transportation of natural gas hydrate, it is important to transport the natural gas hydrate cargo manufactured by the offshore production facility to the transport ship safely and surely and efficiently under the planned operating conditions. In the offloading of natural gas hydrate pellets, since the transported goods are solid cargo, pipes and hoses using a liquid cargo transport swivel cannot be used. Necessary.

  As a natural gas hydrate transfer device, a loading device and a cargo handling method for transporting in a slurry state have been proposed (for example, see Patent Documents 2 and 3). In addition, a cargo handling method and a transportation method in which the material is transported in a pellet form without being made into a slurry have been proposed (see, for example, Patent Document 4). On the other hand, many unloader apparatuses are proposed as a cargo handling apparatus for landing a bulk load such as coal from a transport ship (for example, refer to Patent Document 5).

  However, in these transportation methods, it is assumed that cargo handling will be carried out on the quay or pier in the port, and from the offshore production equipment due to sea conditions such as waves, winds and tides, the same as this offshore production equipment. It is not supposed to be transported offshore, that is, transported to a moving transport ship. Therefore, these off-loading devices have a problem that the offshore production facilities and the relative movements of the offshore production equipment as the transfer source and the transport ship as the transfer destination are significantly larger than those at the landing and cannot be used. is there.

  For example, when a 300m long transport ship is moored to a 300m long offshore production facility (FPSO), assuming a significant wave height of 4m, a period of 8s, a wind speed of 10m / s, a wind speed of 30deg, and a tidal current of 1kt According to the calculation, the relative displacement between the stern of the offshore production facility and the transport ship is a maximum of 0.96 m in the X direction, 2.84 m in the Y direction, and 14.34 m in the Z direction.

A device capable of absorbing such a large relative displacement is not a device of the prior art and needs to be newly developed.
JP 2003-146400 A JP 2003-285792 A JP 2003-171678 A JP 2002-220353 A JP 11-49374 A

The present invention has been made to solve the above-described problems, and the object thereof is to produce a solid material such as natural gas hydrate pellets by sea conditions between a plurality of offshore floating bodies such as offshore production facilities and transport ships. An object of the present invention is to provide an offshore offloading system capable of transferring while absorbing relative displacement between offshore floating bodies.

The offshore offloading system of the present invention for achieving the above object is an offloading system for transferring solids from a first offshore floating body to a second offshore floating body,
A vertical conveyor that receives the solid matter from the first offshore floating body side, a horizontal conveyor that receives the solid matter raised by the vertical conveyor at the receiving portion and transfers it to the tip portion, and is disposed near the tip portion of the horizontal conveyor And a shooter that guides the second offshore floating body to the second offshore floating body while dropping the solid material transferred by the horizontal conveyor, the relative displacement between the first offshore floating body and the second offshore floating body. The offshore offloading device disposed on the first offshore floating body and the second connecting portion that is detachably connected to the first connecting portion on the lower end side of the shooter, and is formed of a bellows structure that absorbs elasticity. Receiving vertical disposed on the second offshore floating body so that the solid matter is received by the second connecting portion and transferred to a discharge port located higher than the second connecting portion. And a receiving horizontal conveyor disposed on the upper deck of the second offshore floating body so as to receive the solid matter from the discharge port of the receiving vertical conveyor and transport it to each hold. The

The expansion and contraction of the accordion structure of the shooter can absorb the relative movement and relative displacement between the floating bodies on both oceans caused by sea conditions, especially large relative movement and relative displacement in the vertical direction. A relatively simple mechanism such as a horizontal conveyor and a shooter can efficiently transfer solids from the first offshore floating body to the second offshore floating body while absorbing the relative displacement caused by the shaking of the offshore floating bodies.
In addition, the first connection portion on the lower end side of the shooter or the second connection portion that is detachably connected to the first connection portion is allowed to rotate about a direction perpendicular to the axial direction of the shooter. Rotational displacement with respect to the rotational axis perpendicular to the axial direction of the shooter caused by shaking between the offshore floating bodies by providing at least one of a rotational joint or a swivel joint that allows rotation with the axial direction of the shooter as the rotational axis And torsion of the shooter can be easily absorbed.

  And this offshore offloading apparatus, when the solid is a pellet-like solid of natural gas hydrate, the first offshore floating body is an offshore production facility, and the second offshore floating body is a transport ship, In particular, a great effect can be achieved.

  Further, in the above-described offshore offloading apparatus, the offshore offloading apparatus is provided so as to be swingable in the yaw direction of the first offshore floating body. According to this configuration, the entire offloading device installed on the first offshore floating body is swung in the yaw direction of the first offshore floating body, that is, automatically or manually swung within a small angle range, and offloading is performed. Since the apparatus can be made to face the second offshore floating body substantially, that is, the relative orientation of the second offshore floating body seen from the first offshore floating body can be made substantially constant, The long period portion of the relative displacement in the horizontal rotation direction (yaw) can be absorbed by this turning. Accordingly, since the amount of absorption by the shooter can be reduced to an amount that can deal with the relative displacement portion corresponding to the wave period, the amount of absorption by the shooter with respect to the relative displacement in the horizontal rotation direction can be greatly reduced. .

  Moreover, this offshore offloading device comprising this vertical conveyor, horizontal conveyor and shooter is disposed on the first offshore floating body side which is the transfer source, and the first connecting portion provided at the lower end of this shooter is the transfer destination. By providing the second connecting portion disposed on the second offshore floating body side so as to be connectable and detachable, the offshore offloading device and the second offshore floating body can be easily connected and disconnected.

In the offshore offloading system , the shooter is configured by connecting a plurality of bellows portions with intermediate joints and pin-connecting the intermediate joints to intersections of pantographs. This configuration prevents the shooter from causing large deformation of the bellows locally even though the force acting on the bellows, especially the vertical load, differs greatly between the upper and lower blocks due to the weight of the shooter. The amount of deformation of the bellows can be made substantially the same.

  Alternatively, the shooter is connected to a plurality of bellows portions with an intermediate joint, an extension wire is provided to prevent the bellows from extending between the intermediate joints, and a tension wire is attached to the lowermost end. Is configured to always apply a predetermined tension. This stretch stop wire can prevent only the upper bellows from being stretched extremely, and the tension wire can increase the effect of following the shooter's lower end connection to the relative displacement during use of the shooter. .

  As a mechanism for applying a predetermined tension to the tension wire, a tension compensator, an auto tension winch, or a mechanism equivalent to these can be used.

According to the offshore offloading system for natural gas hydrate of the present invention, by providing a stretchable shooter having a bellows structure, the relative movement and relative displacement between the first and second offshore floating bodies can be reduced. Therefore, even on the ocean, solids can be easily transferred from the first offshore floating body to the second offshore floating body.

  Further, by providing the offshore offloading device so as to be swingable in the yaw direction of the first offshore floating body, it is possible to easily absorb the azimuth change amount of the second offshore floating body as viewed from the first offshore floating body.

  Further, the offloading device and the second offshore floating body can be easily separated by connecting and disconnecting at the lower end connecting portion of the shooter and the connecting portion on the second offshore floating body side.

Therefore, even when the offshore floating body is swaying under predetermined marine weather conditions, it can be off-loaded while absorbing the relative displacement caused by the swaying of the offshore floating body, so that the offshore that enables the transfer of solids between the offshore floating bodies is possible. An offloading system can be provided.

Embodiments of an offshore offloading system according to the present invention will be described below with reference to the drawings. As shown in FIGS. 1 to 4, the offshore offloading apparatus 1 of this offshore offloading system is solid from the offshore production facility 20 that is the first offshore floating body to the transport ship 30 that is the second offshore floating body. It is an apparatus for transferring natural gas hydrate pellets (hereinafter referred to as NGH pellets).

  The offshore offloading apparatus 1 includes a transport unit including a transport device that transports NGH pellets and a structure unit that supports these transport devices.

  The offshore offloading apparatus 1 has a conveying device that receives NGH pellets from the offshore production facility 20 side, vertically conveys the vertical conveyor 11, and receives the NGH pellets fried on the vertical conveyor 11 at the receiving portion 12 a. The horizontal conveyor (dispensing conveyor) 12 transported to the section 12b and the inlet 12 are arranged in the vicinity of the front end 12b of the horizontal conveyor 12, and the NGH pellets transported by the horizontal conveyor 12 are dropped while the transport ship 30 side And a shooter 13 that leads to The shooter 13 is formed of a bellows structure having sufficient elasticity to absorb relative displacement between the offshore production facility 20 and the transport ship 30.

  The offshore offloading device 1 has a structure having a truss structure that is mounted on the stern deck of the offshore production facility 20 and a truss structure that is placed on the stern base 14 and extends rearward from the stern. And a support portion 15. The support portion 15 is formed by a column portion 15a, a horizontal overhang portion 15b, and a counterweight portion 15c. The support unit 15 is placed on the swivel base 14 in the yaw direction of the offshore production facility 20 (Yaw direction: horizontal rotation direction when stationary), that is, within a predetermined range around the rotation axis C (for example, ± 4 deg from the rear). It is configured to swing or turn.

  And the vertical conveyor 11 is arrange | positioned in the inside of the support | pillar part 15a of the turntable 14 and the support part 15, and the horizontal conveyor 12 is arrange | positioned at the horizontal overhang | projection part 15b of the support part 15, respectively. The horizontal conveyor 12 is disposed substantially horizontally such that the receiving portion 12a is positioned below the discharge portion 11b of the vertical conveyor 11 and the leading end portion 12b is positioned near the leading end portion of the horizontal overhanging portion 15b. And the shooter 13 is hung and provided near the front-end | tip part of this horizontal overhang | projection part 15b, ie, the lower side of the front-end | tip part 12b of the horizontal conveyor 12. FIG.

  The vertical conveyor 11 is formed of a well-known conveyor such as a conveyor having a flange and a cleat used for coal conveyance, wood chip conveyance, waste plastic conveyance, and the like. This conveyor is formed with corrugated flanges over the entire length on both sides in the width direction of the main transport belt, and cleats that divide the spaces between the corrugated flanges at equal intervals in the transport direction. Furthermore, the flanged belt is covered with a flat belt (cover belt) in order to prevent the NGH pellets from spilling out of the flanged belt in the vertical portion. This flat belt is moved in synchronism with the flanged belt. The horizontal conveyor 12 is formed of a trough type belt conveyor. In addition, in order to prevent natural gas from leaking out, these surroundings are configured in an airtight structure, and measures for keeping warm and maintaining heat for maintaining temperature are taken.

  The shooter 13 is a device that guides the NGH pellets transported by the horizontal conveyor 12 to the receiving vertical conveyor 31 that is a transport device on the transport ship 30 side while dropping from above, and adopts a bellows 13c on the transport path. Between the upper end and the lower end, the three degrees of freedom in the vertical direction, the left and right direction, and the front and rear direction are mainly absorbed, and the twist that is the rotational displacement in the axial direction of the fourth degree of freedom is also absorbed. This displacement absorbing function can absorb the relative displacement caused by the shaking of the offshore floating bodies 20 and 30, particularly a large vertical displacement. Moreover, airtightness can be easily maintained by forming the bellows 13c. 1 is connected to the transport ship 30 side.

  Further, in order to easily absorb the twist of the shooter 13, as shown in FIGS. 5 to 8, the mounting portion 13a of the shooter 13 which is a portion attached to the tip of the horizontal overhanging portion 15b at the upper end, and the transport ship at the lower end. A rotary joint such as two universal joints 41, 42, 43, 44, for example, is provided in each of the first connecting portions 13b that are connected to the 30 side. Thereby, the rotation with the direction perpendicular to the axial direction of the shooter 13 as the rotation axis is absorbed. Further, swivel joints 45 and 46 that allow rotation with the axial direction of the shooter 13 as the rotation axis are also provided. Thereby, the twist of the shooter 13 is absorbed.

  In addition, a plurality of bellows 13c portions (six in FIG. 5 and FIG. 6) are provided so that the large deformation of the bellows 13c does not occur locally in the shooter 13 with respect to a large relative displacement due to the fluctuation of the floating bodies 20 and 30 on the ocean. 7 and FIG. 8), and the bellows 13c of each block is connected by an intermediate joint 13e. The bellows 13c is normally formed in a circular cross section, but may have other cross sectional shapes. In addition, regarding the bellows 13c, measures for preventing heat dissipation such as a double structure and measures for preventing static electricity are taken as necessary.

  Further, the force acting on the bellows 13c, particularly the vertical load, is greatly different between the upper and lower blocks due to the dead weight of the shooter 13, so the pantograph shooter 13A using the pantograph mechanism as shown in FIGS. 7 and a wire shooter 13B using a wire suspension mechanism as shown in FIG.

  In the case of the pantograph shooter 13A, as shown in FIGS. 5 and 6, two sets of pantographs 13d are attached to the outer periphery of the bellows 13c so as to sandwich the bellows 13c, and the intermediate joint 13e between the blocks is attached. The intersection is attached to the attachment pin portion 13f. By the pantograph mechanism that absorbs the displacement in the vertical direction, the deformation amount of each bellows portion 13c becomes the same regardless of the expansion and contraction of the shooter 13A. A lifting wire 13i is provided to store the shooter 13A.

  Further, in the case of the wire type shooter 13B, as shown in FIGS. 7 and 8, in order to prevent only the upper bellows 13c from being extended, an extension wire 13g is provided on the bellows 13c of each block. . Furthermore, in order to increase the effect of following the relative displacement during use of the shooter 13, tension wires 13h are provided at four locations around the lowermost end of the bellows 13c, and a mechanism equivalent to a tension compensator, an auto tension winch, etc. (not shown) ) Is always applied to the tension wire 13h.

  In this wire type, since the attachment pin portion 13f for assembling the pantograph 13d is not required for the intermediate joint 13e, the thickness of the intermediate joint 13e can be reduced, so that the weight can be reduced and the length of the bellows 13c can be increased accordingly. Can be increased.

  In the wire shooter 13B, as shown in FIG. 7, when the shooter 13B is contracted, the bellows 13c of each block is contracted and the stretch preventing wire 13g is loosened, but as shown in FIG. In the state where the shooter 13B is fully extended, the extension amount of the bellows 13c of each block is limited while the extension wire 13g is fully extended. And in the state where the shooter 13B is not fully extended, that is, the state between FIG. 7 and FIG. 8, the bellows 13c of the upper block is in a state where the amount of extension is restricted by the extension stopper wire 13g. The block bellows 13c is not stretched.

  And in this offloading device 1, between the 1st connection part 13b of the shooter 13 attached to the transport ship 30 side, and the turntable 14, the X direction (the bow direction at the time of the offshore production equipment at rest), the Y direction Each movement and displacement in the (horizontal direction when the offshore production facility is stationary) and Z direction (vertical direction when stationary is stationary, that is, the vertical direction) are absorbed by the stretchability of the shooter 13.

  Further, the horizontal displacement and horizontal rotational displacement between the offshore production facility 20 and the transport ship 30 are absorbed by the stretchability of the shooter 13 and the rotary joint such as the first connection portion 13b of the shooter 13. In addition, the transport ship seen from the offshore production facility 20 which is a relative rotational displacement which is a transient displacement of the motion between both floating bodies due to the long-period motion based on the long-period drift force in the horizontal rotational displacement. The azimuth change of 30 is absorbed by the swinging or turning of the offloading device 1 in the yaw direction.

  And the offshore production equipment 20 which is the 1st offshore floating body is formed with the box-type barge hull form which cut up the bow tail, for example, in order to take up the volume of the NGH cargo hold 21 as shown in FIG.3 and FIG.4. Based on the remaining capacity at the time of damage, a double bottom and double ship side structure will be adopted. In addition, the ballast combined tank for receiving generated water is arrange | positioned at this double structure part.

  A bow machine room 23, a cargo hold 21, and a stern machine room 24 are provided below the upper deck of the offshore production facility 20, and a living facility 25, an NGH generation plant 26, and a carry-out device serving as a transport device are provided on the upper deck. The side horizontal conveyor 22 is provided so as to extend in the captain direction from the cargo hold 21 as a storage facility toward the stern part.

  In addition, the mooring method of this offshore production facility 20 takes into account the sea conditions and the volumetric efficiency of the cargo hold, and as shown in FIGS. 3 and 4, the exterior is attached to the bow and the yoke is moored to the turret. Then, the living facility 25 is disposed at the bow portion that is on the windward side, and the offloading device 1 is disposed at the stern portion.

  Further, the transport ship 30 is constructed for transporting NGH pellets, and as shown in FIGS. 3 and 4, a hold 33 is disposed in the direction of the ship for the NGH pellets, and a receiving vertical conveyor 31 is disposed at the bow. Furthermore, a receiving horizontal conveyor 32 is arranged on the upper deck. The receiving horizontal conveyor 32 is arranged so as to extend from the discharge port 31 b of the receiving vertical conveyor 31 in the ship length direction and reach each hold 33.

Next, the transfer of NGH pellets by this offshore offloading system will be described. When the transport ship 30 is moored to the offshore production facility 20 by a mooring line, the shooter 13 of the offshore offloading device 1 is lowered from the retracted position to the transport ship 30, and the first connecting portion 13 b at the lower end of the shooter 13 is Is connected to the second connecting portion 31a of the receiving-side vertical conveyor 31 on the transport ship 30 side.

  When this connection is completed, the cooled natural gas is sent into the NGH pellet conveyance path of the offshore offloading apparatus 1 to precool the portion through which the NGH pellets pass. After this pre-cooling is completed, the conveyance of NGH pellets is started.

  The NGH pellets generated in the NGH generation plant 26 of the offshore production facility 20 and stored in the cargo hold 21 which is a storage facility are placed on the carry-out horizontal conveyor 22, and the NGH pellets are transferred to the cargo hold 21 by the carry-out horizontal conveyor 22. From the off-loading apparatus 1 to the receiving portion 11a provided on the lower side of the vertical conveyor 11.

  The NGH pellets transported to the receiving part 11a of the vertical conveyor 11 are raised by the vertical conveyor 11 inside the swivel base 14 and the column part 15a, and from the discharge part 11b provided above the vertical conveyor 11 to the horizontal conveyor 12. To the receiving unit 12a. In the horizontal conveyor 12, the NGH pellets are conveyed from the receiving portion 12a to the tip portion 12b and dropped onto the shooter 13 at the tip portion 12b. That is, the NGH pellets are dropped from the upper part of the offloading apparatus 1 on the offshore production facility 20 through the shooter 13 to the transporting apparatus 31 on the transport ship 30 side.

  The shooter 13 absorbs the NGH pellets while absorbing the movement displacement and twisting of the first connecting portion 13b on the lower side of the shooter 13 caused by the shaking of the offshore production facility 20 and the transport ship 30 due to waves, winds and tides. 2 It leads to the connection part 31a.

  The NGH pellets guided to the second connecting portion 31a are transferred to the receiving side horizontal conveyor 32 by the receiving side vertical conveyor 31 on the transport ship 30 side, and are conveyed to each hold 33. The receiving-side horizontal conveyor 32 is provided with a moving scraper 32a. The moving scraper 32a is moved to the storage target hold 33 to drop NGH pellets into the hold 33. Thereby, the NGH pellets are transferred from the cargo hold 21 of the offshore production facility 20 to the hold 33 of the transport ship 30.

  During this offloading, according to the change in direction of the transport ship 30 as viewed from the offshore production facility 20, the support 15 of the offloading device 1 is swung manually or automatically in the yaw direction on the turntable 14, Absorbs average horizontal azimuth fluctuations caused by long-period motion based on long-period drifting force, and in the X, Y, and Z directions between the offshore production facility 20 and the transport ship 30 corresponding to the wave period. Relative motion and relative displacement are absorbed by the stretchability of the shooter 13. Further, the horizontal rotational displacement is absorbed by the elasticity of the shooter 13 and the rotary joint such as the first connection portion 13b of the shooter 13.

  When each cargo hold 33 is full and cargo handling is completed, the clamp mechanism is released at the first connection portion 13b at the lower end of the shooter 13 and is disconnected from the second connection portion 31a. The lower end of the shooter 13 is covered, and after being separated from the transport ship 30, the hoisting wire is wound up by a winch or the like, and the shooter 13 is retracted and lifted to the storage position to store the shooter 13. Wait until the next transport ship 30 arrives.

  On the other hand, on the transport ship 30 side, after removing the first connection part 13b of the shooter 13, the second connection part 31a of the receiving side vertical conveyor 31 is covered, and the mooring of the transport ship 30 to the offshore production facility 20 is further performed. To leave the offshore production facility 20. And the cargo handling in this offshore production facility 20 is complete | finished, and it sails toward the port aimed at.

  Next, a calculation example of the magnitude of the displacement in the offloading apparatus 1 and the main dimensions of the offloading apparatus 1 corresponding thereto will be shown. In addition, since the magnitude | size of this displacement, a main dimension, etc. change with the offshore production equipment 20, the transport ship 30, the assumed sea state conditions at the time of offshore offloading, etc., the example of calculation shown below is only an example.

  In this calculation, an analysis program based on the high-dimensional boundary element method (copyright registration number P No. 7704-1) is used for wave response analysis of the offshore production facility 20 and the transport ship 30, and the viscous damping against rolling motion is used. In order to consider the force, a 10% linear damping coefficient was used for both the offshore production facility 20 and the transport ship 30, respectively, and a vibration response analysis was performed.

  Based on the result of the shaking response analysis, the shaking response between the first connecting portion 13b at the lower end of the shooter 13 on the offshore production facility 20 and the second connecting portion 31a on the transport ship 30 side in a state where the length of the shooter 13 is fixed. The relative fluctuation analysis of both was performed in consideration of the phase difference of the incident wave. The influence of hydrodynamic mutual interference between the offshore production facility 20 and the transport ship 30 is not taken into consideration.

The size of the offshore production facility (FPSO) 20 is 300m in length, 60m in width, 33m in depth, 16m in draft, 218,000m ³ in cargo volume, and the size of transport ship 30 is 300m in length, 46m in width, deep. The length was 24.5 m, the draft was 14.5 m, and the cargo volume was 174,000 m ³ .

  As for sea conditions, a wave with a significant wave height of 4 m, a period of 8 s, a wind speed of 10 m / s, a wind with a wind direction of 30 deg, a steady flow with a flow rate of 1 kt and a direction of 90 deg. When the transport ship 30 was moored by mooring lines, the following calculated values were obtained.

  The offshore production facility 20 and the transport ship 30 generate a long-period motion based on the long-period drift force in addition to the motion in the wave cycle, and the maximum value of the motion including the long-cycle motion is a surge. 15.8 m, Sway 2 m, and Yaw 7.8 deg. The relative displacement between the offshore floating bodies 20 and 30 is 0.96 m in the X direction, 2.84 m in the Y direction, 14.34 m in the Z direction, and the draft difference between full load and light load is 3.5 m. In this case, it was 17.84 m.

  Therefore, to avoid contact between the offshore production facility 20 and the transport ship 30, a minimum distance of 16 m is required in the horizontal direction. In consideration of safety, the mooring line is 2 to 3 times the maximum displacement. That is, about 32 to 48 m is required. In addition, in order to prevent contact with the offshore production facility 20, it is necessary to always keep the transport ship 30 in a slow speed reverse state. The relative horizontal displacement between the offloading device 1 and the transport ship 30 was 3 m.

  Further, the maximum expansion / contraction amount of the shooter 13 when the encounter angle α with the wave of the offshore production facility 20 is changed to 0 deg, 30 deg and the encounter angle β with the wave of the transport ship 30 is changed to 0 deg, ± 30 deg, ± 60 deg. Is 14.5 m with respect to the wave amplitude of 2 m when α = 30 deg and β = 30 deg.

  Based on these analysis results, when trial design is performed, the offloading apparatus 1 has a height of the vertical conveyor 11 of about 50 m and a length of the horizontal conveyor 12 to prevent contact between the offshore production facility 20 and the transport ship 30. The height of the shooter 13 was about 65 m, the shortest was about 18 m, the longest was about 37 m, and the stroke was about 19 m.

It is a side view showing composition of an offshore offloading system of natural gas hydrate of an embodiment of the invention. It is a top view which shows the structure of the offshore offloading system of FIG. It is a side view which shows the relationship between an offshore offloading system , an offshore production facility, and a transport ship. FIG. 4 is a plan view of FIG. 3. It is a side view which shows the state at the time of the shortening of a pantograph type shooter. It is a side view which shows the state at the time of the expansion | extension of a pantograph type shooter. It is a side view which shows the state at the time of shortening of a wire type shooter. It is a side view which shows the state at the time of the expansion | extension of a wire type shooter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Offloading apparatus 11 Vertical conveyor 11a Receiving part 12 Horizontal conveyor 12a Receiving part 12b Tip part 13 Shooter 13A Pantograph type shooter 13B Wire type shooter 13a Upper end connection part 13b First connection part (lower end connection part)
13c bellows
13d Pantograph 13e Intermediate joint 13f Mounting pin part 13g Stretch wire 13h Tension wire 14 Swivel table 20 Offshore production equipment 21 NGH cargo hold 22 Unloading side horizontal conveyor 30 Transport ship
31 Receiving side vertical conveyor 31a Second connecting part 32 Receiving side horizontal conveyor 33 Funakura 41, 42, 43, 44 Rotary joint 45, 46 Swivel joint

Claims (4)

An offloading system for transferring solids from a first offshore floating body to a second offshore floating body,
A vertical conveyor that receives the solid matter from the first offshore floating body side, a horizontal conveyor that receives the solid matter raised by the vertical conveyor at the receiving portion and transfers it to the tip portion, and is disposed near the tip portion of the horizontal conveyor A shooter that guides the second offshore floating body to the second offshore floating body while dropping the solid material transferred by the horizontal conveyor, and the relative displacement between the first offshore floating body and the second offshore floating body is reduced. An offshore offloading device that is formed in a bellows structure with absorbable elasticity and disposed on the first offshore floating body;
A second connecting portion that is detachably connected to the first connecting portion on the lower end side of the shooter, and receives the solid matter at the second connecting portion and is located at a position higher than the second connecting portion. A receiving vertical conveyor disposed on the second offshore float to be transferred to the outlet;
A receiving horizontal conveyor disposed on the upper deck of the second offshore floating body so as to receive the solid matter from the discharge port of the receiving vertical conveyor and transport it to each hold. Offshore offloading system featuring . The offshore off according to claim 1, wherein the solid is a pellet-like solid of natural gas hydrate, the first offshore floating body is an offshore production facility, and the second offshore floating body is a transport ship. Loading system . 3. The offshore offloading system according to claim 1 or 2, wherein the shooter has a plurality of bellows portions connected by intermediate joints, and the intermediate joints are pin-connected to intersections of pantographs . The shooter is connected to a plurality of bellows portions with an intermediate joint, an extension wire is provided for preventing the bellows between the intermediate joints, and a tension wire is attached to the lowermost end. The offshore offloading system according to claim 1 or 2, wherein a predetermined tension is applied .

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