An adaptive fender method suitable for LNG side-by-side transportation

Abstract

An adaptive fendering method for LNG side-by-side transport is applied to fixed offshore LNG processing platforms such as FSRUs or FLNG. When LNG ships of different sizes side-by-side with a floating LNG receiving and processing platform, the distance between the floating LNG receiving and processing platform and the LNG ship is continuously measured by the stern / bow fixed fenders. This distance is used as a benchmark to derive the theoretical distance between the floating LNG receiving and processing platform and the LNG ship at the stern / bow movable fenders. The movable fenders measure the actual distance between the floating LNG receiving and processing platform and the LNG ship. The movable fenders automatically adjust their position until the actual distance equals the theoretical distance. This allows the fender system to automatically adapt to the parallel mid-hull range of the LNG ship, ensuring that all fender devices are always within the parallel mid-hull of the two ships. This avoids the situation where traditional fender devices cannot adjust their position and are located outside the parallel mid-hull of the LNG ship, resulting in fender failure. This makes the fenders more stable in absorbing the energy of the LNG ship side-by-side transport, and makes LNG side-by-side transport safer.

Description

Technical Field

[0001] The present invention belongs to the field of construction and design of LNG storage tanks for shipping, and in particular relates to an adaptive fender method suitable for LNG side-by-side transportation. Background Art

[0002] Currently, floating LNG receiving and processing platforms (FSRU, FLNG, etc.) are favored by more and more countries and regions due to their advantages such as short construction period, low investment and good environmental protection.

[0003] When transferring LNG between the floating LNG receiving and processing platform and the LNG ship, the side-by-side external transmission method is adopted, that is, one side of the LNG ship is moored on one side of the floating LNG receiving and processing platform, and the two are connected by cables and equipped with fenders to avoid direct collision between the two.

[0004] The fender device is installed on the floating LNG receiving and processing platform. A fender is set at each end of the parallel mid-body, and a fender is set before and after the manifold. [1] .

[0005] [1] China Classification Society, Guidelines for Ship-to-Ship Transfer. [S], CCS.2019.

[0006] Currently, all fenders are fixedly installed. The positions of the fenders on both sides of the parallel mid-hull are determined based on the parallel mid-hull range of the floating LNG receiving and processing platform.

[0007] However, LNG carriers vary in size and specifications, leading to significant variations in the length of their parallel mid-hulls. When the parallel mid-hull of an LNG carrier is shorter than that of a floating LNG receiving and processing platform, the fenders at both ends of the platform's parallel mid-hull cannot contact the hull plating of the LNG carrier, resulting in partial or complete dangling. This in turn renders the fenders in that area ineffective in avoiding collisions, increasing the risk of LNG being transported alongside. Summary of the Invention

[0008] To solve the above problems, the present invention proposes an adaptive fender method suitable for LNG side-by-side transportation, the technical solution adopted is:

[0009] The invention discloses an adaptive fender method suitable for LNG side-by-side transportation. A movable fender is fixed at both ends of the bow and stern of the parallel mid-body deck of a floating LNG receiving and processing platform, and a fixed fender is fixed at both ends of the manifold area of ​​the floating LNG receiving and processing platform.

[0010] The movable fender includes a track, an automatic cable winch and a fender body. The track is fixed on the deck. The track includes a track support frame and a rack. Limiting members are set at both ends of the track support frame, and the rack is located in the middle of the track support frame. The track is slidably connected to the automatic cable winch, which includes a winch frame. A gear is fixed at the bottom center of the winch frame. The gear is engaged with the rack teeth. Drums are fixed at both ends of the winch frame. The two drums are coaxially connected. The automatic cable winch is equipped with a gear box. The gear The gear box is connected to the two drum shafts, the gear box is controlled by the first motor, a cable is wound on the drum, and both ends of the fender body are fixedly connected to the cable. The angle between the cable and the axis of the fender body is β, 45°≤β≤60°; an acoustic rangefinder is also provided at the end of the fender body of the movable fender. The fender body is located at the bow of the fender parallel to the mid-body deck, and the acoustic rangefinder is fixed at one end near the bow. The fender body is located at the stern of the fender parallel to the mid-body deck, and the acoustic rangefinder is fixed at one end near the stern.

[0011] The fixed fender consists of a fender body and a cable holder, the cable holder is fixed on the deck, two ends of the fender body are connected with cables, the other end of the cable is connected to the cable holder (511), and the angle between the cable and the axis of the fender body is 45°≤β≤60°.

[0012] The theoretical distance from the mobile fender sonic rangefinder located at the stern to the outer plate of the LNG ship should be Lal:

[0013]

[0014] The theoretical distance from the mobile fender sonic rangefinder located at the bow to the outer plate of the LNG ship is to be Lfl:

[0015]

[0016] The mobile fender sonic rangefinder at the stern measures the actual distance Las to the LNG carrier. When Las>Lal, the cable winch at the stern moves toward the middle of the ship, driving the mobile fender at the stern to move toward the middle of the ship until Las=Lal, at which point the cable winch at the stern stops moving. The value of Las is measured in real time and continuously compared with Lal.

[0017] The mobile fender sonic rangefinder at the bow measures the actual distance Lfs to the LNG carrier. When Lfs>Lfl, the cable winch at the bow moves toward the midship, driving the mobile fender at the bow to move toward the midship until Lfs=Lfl, at which point the cable winch at the bow stops moving. The value of Lfs is measured in real time and continuously compared with Lfl.

[0018] The above-mentioned adaptive fender method suitable for LNG side-by-side transportation further comprises the gear being driven by a second motor.

[0019] The above-mentioned adaptive fender method suitable for LNG side-by-side transportation, further, the fender body is an inflatable fender.

[0020] The above-mentioned adaptive fender method suitable for LNG side-by-side transportation further comprises eye plates fixed at both ends of the fender body, and cables are connected to the eye plates.

[0021] The above-mentioned adaptive fender method suitable for LNG side-by-side transportation, further, the winch frame is a steel winch frame.

[0022] The above-mentioned adaptive fender method suitable for LNG side-by-side transportation further comprises the following steps: a fairlead hole is provided at the front end of the drum, and the cable passes through the fairlead hole and is connected to the end of the fender body.

[0023] The above-mentioned adaptive fender method suitable for LNG side-by-side transportation further has a reel speed Vj ≥ 10 m / min.

[0024] The above-mentioned adaptive fender method suitable for LNG side-by-side transportation further comprises the following steps: the track support frame is a steel support frame, a plurality of support legs are fixed to the lower surface of the track support frame, and the bottoms of the support legs are welded to the deck.

[0025] The above-mentioned adaptive fender method suitable for LNG side-by-side transportation, further, has the length of the track support frame being 1.5 to 2 times the length of the automatic cable winch.

[0026] The above-mentioned adaptive fender method suitable for LNG side-by-side transportation further has the following advantages: the height of the track support frame is not less than 1m and not more than 1.4m.

[0027] The above-mentioned adaptive fender method suitable for LNG side-by-side transportation further comprises a plurality of rollers being provided on the bottom of the winch. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic structural diagram of the present invention;

[0029] Figure 2 It is a schematic diagram of the structure of an automatic cable winch;

[0030] Figure 3 It is a schematic diagram of the movable fender structure;

[0031] Figure 4 It is a schematic diagram of the track structure;

[0032] Figure 5 LNG ship docking diagram;

[0033] Figure 6 It is a control logic diagram of the present invention;

[0034] Among them: 11- movable fender, 41- fixed fender, 114- cable, 21- automatic cable winch, 211- winch frame, 212- drum, 216- gearbox, 31- track, 312- rack, 313- limiter, 511- cable anchor, A- floating LNG receiving and processing platform, Ac- LNG ship, B- flat side line of floating LNG receiving and processing platform (parallel to the mid-body range line), Bc- LNG ship width, C- floating LNG receiving and processing platform header area, Cc- LNG ship header area, Dc- LNG ship berthing draft, Df- inflatable fender diameter, Ds- full load draft, Db- ballast draft, E- inflatable fender absorption energy, Ha-LNG ship effective height, Hb-floating LNG receiving and processing platform effective height, Hg-track support frame height, Lc-rack length, Lf-inflatable fender length, Lg-track support frame length, Lj-center distance between stern drum and bow drum, Lag-distance to stern fixed fender sonic rangefinder, Lfg-distance to bow fixed fender sonic rangefinder, Laf-distance from stern movable fender sonic rangefinder to stern fixed fender sonic rangefinder, Lff-distance from stern fixed fender sonic rangefinder to bow fixed fender sonic rangefinder, Lfa-distance from bow fixed fender sonic rangefinder to bow movable fender sonic rangefinder, Lal - theoretical distance from the stern mobile fender sonic rangefinder to the outer plate of the LNG ship, Lfl - theoretical distance from the bow mobile fender sonic rangefinder to the outer plate of the LNG ship, Las - actual distance from the stern mobile fender sonic rangefinder to the LNG ship, Lfs - actual distance from the bow mobile fender sonic rangefinder to the LNG ship, Ma - original position of the stern mobile fender, Mf - original position of the bow mobile fender, α - maximum roll angle of the LNG ship, β - angle between the cable and the axis of the inflatable fender. DETAILED DESCRIPTION

[0035] The present invention will be further described with reference to the accompanying drawings.

[0036] like Figure 1 、 2As shown in Figures 3 and 4, an adaptive fender method suitable for LNG side-by-side transportation is installed on a floating LNG receiving and processing platform or FSRU or FLNG. Two movable fenders are located at both ends of the parallel mid-body of the floating LNG receiving and processing platform, and two fixed fenders are located at both ends of the manifold area of ​​the floating LNG receiving and processing platform. The movable fender consists of a track and an automatic cable winch. The track is fixed on the deck. The track includes a track support frame and a rack. Limiting parts are set at both ends of the track support frame. When the cable winch at the stern or bow touches the limiting parts, the traveling mechanism automatically stops, thereby preventing the cable winch at the stern or bow from derailing. The rack is located in the middle of the track support frame. The track is slidably connected to an automatic cable winch. This automatic cable winch consists of a winch frame with a gear fixed to the center of its base, meshing with the rack. Drums are coaxially connected at each end of the winch frame and equipped with a gearbox connected to the two drum shafts. The gearbox is controlled by a first motor. Cables are wound around the drums, which are fixed to the ends of the fender body at an angle of 45° ≤ β ≤ 60° to the main axis. The first motor drives the gearbox, rotating the drums to retract and extend the fender body. An acoustic rangefinder is also installed at the end of the fender body, located near the bow or stern.

[0037] The fixed fender consists of a fender body and a cable holder. The cable holder is fixed on the deck. Cables are connected to both ends of the fender body, and the other end of the cable is connected to the cable holder. The angle between the cable and the axis of the fender body is 45°≤β≤60°.

[0038] like Figure 5 、 6 As shown in the figure, when the floating LNG receiving and processing platform needs to carry out LNG transfer operations, the LNG carrier gradually approaches the floating LNG receiving and processing platform in an arbitrary posture. During this approach, the acoustic rangefinders on the fixed stern fender and the fixed bow fender begin operating. Because the LNG carrier cannot always maintain a parallel attitude with the floating LNG receiving and processing platform while berthing, the measured distance at the fixed stern fender acoustic rangefinder is Lag, and the distance at the fixed bow fender acoustic rangefinder is Lfg. These two distances are only the same when the floating LNG receiving and processing platform and the LNG carrier are parallel; in most other cases, they are different. At the same time, the distance from the movable stern fender acoustic rangefinder to the fixed stern fender acoustic rangefinder is Laf, the distance from the fixed stern fender acoustic rangefinder to the fixed bow fender acoustic rangefinder is Lff, and the distance from the fixed bow fender acoustic rangefinder to the movable bow fender acoustic rangefinder is Lfa.

[0039] The inflatable fender length Lf is selected based on the inflatable fender diameter Df in accordance with ISO 17357:2002. The center distance between the stern and bow mandrels, Lj, is Lf + 2 × Hb × tan45°. The track support frame length Lg is between 1.5 and 2 times the center distance between the stern and bow mandrels, Lj, i.e., 1.5Lj ≤ Lg ≤ 2Lj. The track support frame height Hg is not less than 1m and not more than 1.4m, i.e., 1m ≤ Hg ≤ 1.4m, to facilitate maintenance.

[0040] The rack is mounted on a track support frame. The rack length, Lc, must be no less than twice the length of the inflatable fender, Lf, and need not be greater than three times Lf, i.e., 2Lf ≤ Lc ≤ 3Lf. The rack length corresponds to the stroke of the stern / bow cable winches. A value of 2Lf ≤ Lc ensures sufficient travel range for the stern / bow mobile fenders to accommodate a wide range of LNG carrier types, especially smaller ones. A value of Lc ≤ 3Lf prevents the travel of the stern / bow mobile fenders from exceeding an unrealistic length.

[0041] The acoustic rangefinder measures the horizontal distance from the movable fender to the LNG carrier. The measured horizontal distance data is transmitted to the automatic cable winch, which processes the data.

[0042] The theoretical distance from the mobile fender sonic rangefinder located at the stern to the outer plate of the LNG ship should be Lal:

[0043]

[0044] The theoretical distance from the mobile fender sonic rangefinder located at the bow to the outer plate of the LNG ship is to be Lfl:

[0045]

[0046] At this point, the sonic rangefinder on the mobile fender at the stern measures the actual distance to the LNG carrier, Las. If Las > Lal, the mobile fender at the stern is not within the parallel center hull of the LNG carrier. If Las = Lal, the mobile fender at the stern is within the parallel center hull of the LNG carrier. Because the hull is constantly in motion in the ocean, the values ​​of Las and Lal must be continuously compared. When the result stabilizes, and Las > Lal, the cable winch at the stern moves toward the center of the ship, driving the mobile fender toward the center while continuing to measure Las and compare it with Lal. The cable winch at the stern stops moving until the result stabilizes at Las = Lal. At this point, the mobile fender at the stern is within the parallel center hull of the floating LNG receiving and processing platform and the LNG carrier, fully functioning as a fender.

[0047] The acoustic rangefinder on the bow mobile fender measures the actual distance to the LNG carrier, Lfs. If Lfs > Lfl, the bow mobile fender is not within the parallel center hull of the LNG carrier. If Lfs = Lfl, the bow mobile fender is within the parallel center hull of the LNG carrier. Because the ship is constantly in motion at sea, the values ​​of Lfs and Lfl must be continuously compared. When the result stabilizes (Lfs > Lfl), the bow cable winch moves toward the center of the ship, moving the bow mobile fender toward the center of the ship while continuing to measure Lfs and compare it with Lfl. The bow cable winch stops moving until the result stabilizes at Lfs = Lfl. At this point, the bow mobile fender is within the parallel center hull of the floating LNG receiving and processing platform and the LNG carrier, fully functioning as a fender.

[0048] After the movement is completed, the movable fenders located at the bow and stern remain stationary until the LNG siding transfer operation is completed. After the LNG ship leaves the floating LNG receiving and processing platform, the cable winch located at the stern moves toward the stern, driving the movable fender located at the stern to move toward the stern to the initial position Ma; the cable winch located at the bow moves toward the bow, driving the movable fender located at the bow to move toward the bow to the initial position Mf.

[0049] Thus, the working process of the adaptive fender method suitable for LNG side-by-side transportation in the process of an LNG side-by-side transportation operation of the present invention is completed.

Claims

1. An adaptive fender method suitable for LNG side-by-side transportation, characterized in that: A movable fender (11) is fixed at each end of the bow and stern of the parallel mid-body deck of the floating LNG receiving and processing platform, and a fixed fender (41) is fixed at each end of the manifold area of ​​the floating LNG receiving and processing platform; The movable fender comprises a track (31), an automatic cable winch (21) and a fender body (111). The track is fixed on the deck, and the track comprises a track support frame (311) and a rack (312). Limiting members (313) are provided at both ends of the track support frame, and the rack is located in the middle of the track support frame. The track is slidably connected to the automatic cable winch, and the automatic cable winch comprises a winch frame (211). A gear (217) is fixed at the bottom center of the winch frame, and the gear is meshed with the rack teeth. A drum (212) is fixed at both ends of the winch frame, and the two drums are coaxially connected. The automatic cable winch is connected to the winch frame. The winch is equipped with a gear box (216), which is connected to two drum shafts and is controlled by a first motor. A cable (114) is wound around the drum, and both ends of the fender body are fixedly connected to the cable. The angle between the cable and the axis of the fender body (111) is β, 45°≤β≤60°. The end of the fender body of the movable fender is also provided with an acoustic rangefinder (112). The fender body is located parallel to the bow of the mid-body deck, and the acoustic rangefinder is fixed to one end near the bow. The fender body is located parallel to the stern of the mid-body deck, and the acoustic rangefinder is fixed to one end near the stern. The fixed fender consists of a fender body and a cable holder, the cable holder is fixed on the deck, two ends of the fender body are connected with cables, the other end of the cable is connected to the cable holder (511), and the angle between the cable and the axis of the fender body is 45°≤β≤60°; The theoretical distance from the mobile fender sonic rangefinder located at the stern to the outer plate of the LNG ship should be Lal: The theoretical distance from the mobile fender sonic rangefinder located at the bow to the outer plate of the LNG ship is to be Lfl: The mobile fender sonic rangefinder at the stern measures the actual distance Las to the LNG carrier. When Las>Lal, the cable winch at the stern moves toward the midship, driving the mobile fender at the stern to move toward the midship until Las=Lal, at which point the cable winch at the stern stops moving. The value of Las is measured in real time and continuously compared with Lal. The mobile fender sonic rangefinder at the bow measures the actual distance Lfs to the LNG carrier. When Lfs>Lfl, the cable winch at the bow moves toward the midship, driving the mobile fender at the bow to move toward the midship until Lfs=Lfl, at which point the cable winch at the bow stops moving. The value of Lfs is measured in real time and continuously compared with Lfl.

2. The adaptive fender method for LNG side-by-side transportation according to claim 1, characterized in that: The gear is driven by a second motor.

3. The adaptive fender method for LNG side-by-side transportation according to claim 1, characterized in that: The main body of the fender is an inflatable fender.

4. The adaptive fender method for LNG side-by-side transportation according to claim 1, characterized in that: Eye plates (113) are fixed at both ends of the fender body, and cables are connected to the eye plates.

5. The adaptive fender method for LNG side-by-side transportation according to claim 1, characterized in that: The winch frame is made of steel.

6. The adaptive fender method for LNG side-by-side transportation according to claim 1, characterized in that: A cable guide hole is provided at the front end of the drum, and the cable passes through the cable guide hole and is connected to the end of the fender body.

7. The adaptive fender method for LNG side-by-side transportation according to claim 1, characterized in that: Roll speed Vj≥10m / min.

8. The adaptive fender method for LNG side-by-side transportation according to claim 1, characterized in that: The track support frame is a steel support frame, and a plurality of support legs are fixed on the lower surface of the track support frame, and the bottom of the support legs is welded to the deck.

9. The adaptive fender method for LNG side-by-side transportation according to claim 1, characterized in that: The length of the track support frame is 1.5 to 2 times the length of the automatic cable winch, and the height of the track support frame is not less than 1m and not more than 1.4m.

10. The adaptive fender method for LNG side-by-side transportation according to claim 1, characterized in that: A plurality of rollers (218) are also provided on the bottom of the winch.

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