Manufacturing method of LNG shipping C-shaped double-body storage tank

Abstract

The invention discloses a manufacturing method of a C-shaped double-body storage tank for LNG (Liquefied Natural Gas) shipping, which is characterized in that the C-shaped double-body storage tank is firstly divided into two single tanks and a bulkhead, each single tank is sequentially divided into a tank body part and an end socket part, the tank body part comprises a plurality of annular shell rings, and a track and a roller structure are arranged on a platform; the roller structure moves on the track to drive the to-be-welded annular shell ring to be aligned, the roller structure is used for driving the annular shell ring to rotate around the axis of the annular shell ring, assembly welding of the tank body part is carried out, and the welding time can be greatly shortened. Besides, the end socket part is prepared by taking the annular shell ring as a jig frame, so that a roller structure is conveniently used for subsequently driving the annular shell ring to rotate so as to enable the end socket part to rotate, the welding and fixing of the end socket part and the tank body part are quickly completed, and meanwhile, the design of assembling and welding the hemispherical end socket is carried out by taking the annular shell ring adjacent to the hemispherical end socket as the jig frame; the problems that welding shrinkage is difficult to control due to the fact that the number of end socket plates is large, and butt joint of a hemispherical end socket and a tank body is affected can be solved.

Description

Technical Field

[0001] The present invention relates to the field of ship technology, and in particular to a method for manufacturing a C-type double-body storage tank for LNG shipping. Background Art

[0002] Natural gas is a more efficient and clean energy source, accounting for more than 25% of the world's primary energy structure, and may surpass oil to become the world's largest main energy source by 2040. The application of ultra-low temperature liquefaction technology can turn natural gas into liquid, greatly reducing its volume, which is very conducive to long-distance maritime transportation. At present, most of the global LNG (liquefied natural gas) transportation methods are carried out by sea by LNG tankers, accounting for more than 80% of the transportation methods.

[0003] In order to improve transportation efficiency, promote the matching degree between LNG storage tanks and ship cargo holds, and ensure the maximum utilization of cargo capacity, large LNG transport ships generally use C-type double-hull tanks. The C-type double-hull tank is quite different from the C-type single-hull tank in terms of structural layout and construction technology. In addition to fully considering factors such as strength, sloshing load, wave load, acceleration, etc., the feasibility, convenience and construction quality of the construction technology of the tank structure are extremely important.

[0004] In the prior art, the patent with publication number CN 110356512 B discloses a liquefied natural gas shipboard catamaran storage tank and its manufacturing method. After the shell plate assembly and welding are completed, the two first cylinder sections are welded to form an ∞-shaped structure, and then the bulkhead plate is inserted between the first cylinder sections on both sides and welded and fixed. Then, the two left heads are hoisted on both sides of the bulkhead plate and stacked on the first cylinder section for welding and fixing, so as to assemble to form the tank body section I; the two second cylinder sections are welded to form an ∞-shaped structure, and then the bulkhead plate is inserted between the second cylinder sections on both sides and welded and fixed. Then, the two third cylinder sections are hoisted on the bulkhead plate respectively. The two fourth cylinder sections are respectively installed on both sides of the bulkhead plate and stacked on the third cylinder section for welding and fixing, so as to assemble the tank body section II; the two fifth cylinder sections are welded to form an ∞-shaped structure, and then the bulkhead plate is inserted between the fifth cylinder sections on both sides and welded and fixed, and then the two right heads are hoisted on both sides of the bulkhead plate and stacked on the fifth cylinder section for welding and fixing, so as to assemble the tank body section III; finally, the tank body section I, tank body section II and tank body section III are welded and fixed in sequence to form a double-body storage tank. The above manufacturing method is manufactured by reasonable segmentation and petalization, and can be manufactured in a limited space using existing tools and equipment. However, the above method is to divide the two storage tanks as a whole, first weld to form an ∞-shaped structure and then weld them in sequence. Due to the huge volume of the storage tank, when the double-body storage tank is manufactured by the above method, the position of the cylinder section to be welded is fixed, and workers need to move up and down to weld the parts to be welded in the storage tank. The welding process is relatively complicated, the utilization rate of automated equipment is low, and the welding takes a long time.

[0005] In view of this, it is necessary to design a manufacturing method of a C-type double-body storage tank for LNG shipping to solve the above problems. Summary of the invention

[0006] The purpose of the present invention is to provide a method for manufacturing a C-type double-body storage tank for LNG shipping, which first completes the manufacture of a single C-type storage tank and then closes the whole tank, thereby solving the problems that the C-type double-body storage tank is inconvenient to weld, the utilization rate of automated equipment is low, and the manufacturing is time-consuming.

[0007] To achieve the above-mentioned object of the invention, the present invention provides a method for manufacturing a C-type double-body storage tank for LNG shipping, comprising the following steps: S1. A track and a roller structure that can move along the track are set on the platform for tank assembly, and the cylinder section plate and the head plate are pressed according to the design size; S2, assembling and welding a plurality of cylinder segment plates into an annular cylinder segment; using the annular cylinder segment as a tire frame, installing a plurality of head plates on the annular cylinder segment to form a head portion; S3, coaxially placing the two annular cylinder segments on two roller structures respectively, moving the roller structures along the track until the two annular cylinder segments are circumferentially aligned, and then performing preliminary fixing processing on the two annular cylinder segments; then using the roller structure to drive the two annular cylinder segments to rotate synchronously around their axis, and performing circumferential welding on the two annular cylinder segments; S4, according to the processing operation of step S3, assembling and welding a plurality of annular cylinder segments to form a cylindrical tank body of the storage tank; at the same time, placing the annular cylinder segment portion of the head portion on the roller structure, and according to the processing operation of step S3, respectively installing the two head portions at both ends of the tank body to form a first single tank; S5, assembling a second monomer tank according to steps S2 to S4; S6. Openings are cut on the two single tanks respectively, and after the bulkhead is installed at the opening on one of the single tanks, the openings of the two single tanks are aligned and welded to obtain a C-type double-body storage tank.

[0008] As a further improvement of the present invention, in step S1, the head plate includes an equatorial plate, a temperate plate and a polar plate.

[0009] As a further improvement of the present invention, in step S1, the track includes a transverse track and a longitudinal track, and the roller structure is arranged on the track through a slider, so that the roller structure can move along the transverse track or the longitudinal track.

[0010] As a further improvement of the present invention, in step S1, the cylinder segment plate includes a first arc plate made of low-temperature resistant alloy steel and a second arc plate made of ordinary carbon steel for installation at a corresponding opening position.

[0011] As a further improvement of the present invention, in step S3, the welding process is to perform spot welding, root welding and submerged arc welding on the two annular cylinder segments in sequence.

[0012] As a further improvement of the present invention, no base welding is performed between the second arc plates of the two annular cylinder segments.

[0013] As a further improvement of the present invention, in step S3, the preliminary fixing process is to use a plurality of fasteners to fix the two annular cylinder segments.

[0014] As a further improvement of the present invention, in step S6, the specific operation of aligning the openings of the two monomer tanks is: keeping the monomer tank without the bulkhead plate installed stationary, and moving the monomer tank with the bulkhead plate installed until the openings of the two monomer tanks are aligned.

[0015] The beneficial effects of the present invention are: 1. The present invention adopts the process of first building a single tank and then assembling the whole tank, which solves the problem that the non-cylindrical C-type double-body storage tank cannot rotate circumferentially and is not convenient for using automated welding equipment. The roller structure drives the annular cylinder segment to rotate so as to weld each annular cylinder segment and the annular cylinder segment and the head portion in sequence along the axial direction of the single tank, which can greatly reduce the manufacturing time and save costs.

[0016] 2. The present invention uses adjacent annular cylinder segments as a frame for construction during the assembly and welding process of the tank head, which can solve the problem that the welding shrinkage of the head plates is difficult to control due to the large number, thus affecting the connection between the head and the tank body. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall structure of a C-type double-body storage tank prepared according to the manufacturing method of a C-type double-body storage tank for LNG shipping of the present invention.

[0018] Figure 2 This is a schematic diagram of the assembly of the annular cylinder segment.

[0019] Figure 3 This is a schematic diagram of the assembly of the head.

[0020] Figure 4 This is a schematic diagram of the assembly of the tank body.

[0021] Figure 5 This is a schematic diagram of the structure of a single tank obtained by segmented welding.

[0022] Figure 6 This is a schematic diagram of the cutting of a single tank.

[0023] Figure 7 It is a schematic diagram of the structure of a single tank equipped with a bulkhead.

[0024] Figure 8 This is a schematic diagram of the docking of two single tanks.

[0025] Reference numerals 10. Tank body; 11. Annular cylinder section; 111. First arc plate; 112. Second arc plate; 20. End plate; 21. Equatorial plate; 22. Temperate plate; 23. Polar plate; 31. Opening; 32. Bulkhead plate; 41. Longitudinal track; 42. Transverse track; 50. Roller structure. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the scheme of the present invention are shown in the drawings, while other details that are not closely related to the present invention are omitted.

[0028] In addition, it should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0029] like Figure 1 , Figure 2 and Figure 7 As shown, the present invention divides the C-type double-body storage tank according to the convenience of construction process and the convenience of assembly quality. The C-type double-body storage tank is first divided into two single tanks and a bulkhead plate 32, and the single single tank is further divided into a cylindrical tank body portion 10 and a head portion 20, wherein the tank body portion 10 is divided into a plurality of annular cylinder segments 11 according to the manufacturing process, and a single annular cylinder segment 11 is further divided into 3-5 cylinder segment plates.

[0030] like Figure 2-Figure 8 As shown, a method for manufacturing a C-type double-body storage tank for LNG shipping is provided, comprising the following steps: S1. A track and a roller structure 50 that can move along the track are arranged on a platform for assembling a storage tank, and the cylinder section plate and the head plate are pressed according to the designed dimensions; S2, assembling and welding a plurality of cylinder segment plates into an annular cylinder segment 11; using the annular cylinder segment 11 as a tire frame, installing a plurality of head plates on the annular cylinder segment 11 to form a head portion; S3, using a hoisting device to coaxially place the two annular cylinder segments 11 on two roller structures 50 respectively, and move the roller structure 50 along the track until the two annular cylinder segments 11 are circumferentially aligned, and then perform a preliminary fixing process on the two annular cylinder segments 11; then drive the roller structure 50 to rotate the annular cylinder segments 11 around their axis, and perform circumferential welding on the two annular cylinder segments 11; S4, according to the processing operation of step S3, assembling and welding a plurality of annular cylinder segments 11 to form a cylindrical tank body 10 of the storage tank; at the same time, the annular cylinder segment 11 of the end portion 20 is placed on the roller structure 50, and according to the processing operation of step S3, two end portions 20 are respectively installed at both ends of the tank body 10 to form a first single tank; S5, assembling a second monomer tank according to steps S2 to S4; S6. Mark the installation position of the bulkhead plate 32 on the single tank according to the design size, cut openings 31 for installing the bulkhead plate 32 on the two single tanks respectively, install the bulkhead plate 32 at the opening 31 on one of the single tanks, align the openings 31 of the two single tanks and weld them to obtain a C-type double-body storage tank.

[0031] Specifically, in step S1, the head plate includes an equatorial plate 21, a temperate plate 22 and a polar plate 23 ( Figure 3 ).

[0032] For example, Figure 2 As shown, the annular cylinder segment 11 is divided into 5 cylinder segment plates, and the cylinder segment plates include a first arc plate 111 made of low-temperature resistant alloy steel and a second arc plate 112 made of ordinary carbon steel. Since the construction material of the C-type double-body storage tank is generally low-temperature resistant alloy steel, the cost is relatively expensive. In the subsequent manufacturing process, the position on the storage tank for installing the bulkhead plate 32 needs to be cut off. Therefore, when the annular cylinder segment 11 is assembled in the early stage, the second arc plate 112 made of relatively cheap materials can be used to make the part that needs to be cut off later according to the design size, so that when the single tank is assembled in the early stage, the second arc plate 112 is used to fill the part that needs to be cut off later, so that four first arc plates 111 and one second arc plate 112 form the annular cylinder segment 11, that is, the side wall of the annular cylinder segment 11 can be placed on the roller structure 50, so that the annular cylinder segment 11 can be rotated under the action of the roller structure 50 to facilitate the circumferential automatic welding of the two cylinder segments, thereby improving the construction efficiency and manufacturing accuracy of the C-type double-body tank, ensuring the construction quality and reducing the construction cost. In addition, the second arc plate 112 subsequently cut off can be recycled to further save construction costs.

[0033] Specifically, in step S1, the track includes a transverse track 42 and a longitudinal track 41, and the transverse track 42 and the longitudinal track 41 each include two guide rails arranged at intervals, wherein the longitudinal track 41 is arranged along the axial direction of the single tank ( Figure 8 ); The roller structure 50 is arranged on the track through a slider, so that the roller structure 50 can move along the transverse track 42 or the longitudinal track 41. Exemplarily, a groove is arranged at the bottom of the slider, and when the slider moves along the longitudinal track 41 to the intersection of the longitudinal track 41 and the transverse track 42, the slider is adjusted from being clamped on the longitudinal track 41 to being clamped on the transverse track 42 by adjusting the slider orientation, that is, the slider can be moved along the transverse track 42. Exemplarily, when adjusting the slider orientation, the tank body can be supported by a bracket, that is, the slider orientation can be adjusted so that the slider can move along the transverse track 42, and then in the subsequent docking process of the two single tanks, the relative positions of the single tanks can be adjusted.

[0034] Taking the longitudinal track 41 as an example, the roller structure 50 includes a frame body perpendicular to the longitudinal track 41 , rollers symmetrically arranged at two ends of the frame body, and a driving member for driving the rollers to rotate.

[0035] Specifically, in step S2, the specific operation of assembling and welding a plurality of cylinder segment plates into an annular cylinder segment 11 is as follows: an assembly frame is set up based on the diameter of the tank body 10, four first arc plates 111 and second arc plates 112 are assembled in sequence to form an annular cylinder segment 11, and the connection between two adjacent arc plates is welded.

[0036] Specifically, Figure 3 As shown, in step S2, the manufacturing process of the head portion 20 is specifically as follows: the annular cylinder segment 11 is placed vertically so that the axial direction of the annular cylinder segment 11 is parallel to the vertical direction, and a plurality of equatorial plates 21, a plurality of temperate plates 22, and a plurality of polar plates 23 are sequentially assembled and welded circumferentially using the annular cylinder segment 11 as a tire frame, so as to sequentially form the equator, the temperate zone, and the polar zone along the vertical upward direction, so that the equator, the temperate zone, and the polar zone together form a hemispherical head, and then the welding of the hemispherical head and the annular cylinder segment 11 adjacent to the hemispherical head is completed to form the head portion 20. By welding the hemispherical head to the annular cylinder section 11, it is convenient to use the roller structure 50 to drive the annular cylinder section 11 to rotate, that is, to rotate the head section 20, so as to quickly complete the welding and fixation of the head section 20 and the tank body 10. At the same time, by assembling and welding the hemispherical head with the annular cylinder section 11 adjacent to the hemispherical head as a tire frame, it can solve the problem that the welding shrinkage of the head plates is difficult to control due to the large number, thereby affecting the connection between the hemispherical head and the tank body.

[0037] Specifically, in step S3, the preliminary fixing process is to use a number of fasteners to fix the edges of the two cylinder segments, so that the two roller structures 50 can be driven to rotate synchronously to drive the two annular cylinder segments 11 to rotate synchronously for circumferential welding. The two annular cylinder segments 11 can be fixed as a whole through the preliminary fixing process, thereby improving the stability of the annular cylinder segments 11 during rotation.

[0038] Specifically, in step S3, the welding process is to perform spot welding and backing welding on the annular seams of the two annular cylinder segments 11 in sequence, and after the backing welding is completed, the circumferential welding of the two annular cylinder segments 11 is completed by using automatic submerged arc welding. Among them, the backing welding process is not performed between the second arc plates 112 of the two annular cylinder segments 11, so as to facilitate the subsequent dismantling process.

[0039] For example, Figure 4 and Figure 5As shown, the body 10 of the single tank of the present invention is composed of six annular barrel sections 11, which are divided into the first barrel section, the second barrel section, the third barrel section, the fourth barrel section, the fifth barrel section and the sixth barrel section in the horizontal direction. When the body 10 is assembled and welded, the first barrel section and the second barrel section are coaxially placed on two roller structures 50 located on the longitudinal track 41, respectively, and the roller structures 50 are moved along the longitudinal track until the two barrel sections are aligned and initially fixed, and then the two barrel sections are synchronously driven to rotate by the two roller structures 50 to weld the first barrel section and the second barrel section. After the welding is completed, the first barrel section and the second barrel section that have been welded are supported by a bracket, and then the first barrel section and the second barrel section are welded. One of the roller structures 50 is moved out along the longitudinal track 41, and the position of the other roller structure 50 is adjusted to be located in the middle of the whole composed of the first cylinder segment and the second cylinder segment. After the third cylinder segment is hoisted onto the moved out roller structure 50, the moved out roller structure 50 is moved along the longitudinal track 41 to drive the third cylinder segment to align with the side of the second cylinder segment away from the first cylinder segment and initially fix it. At the same time, the bracket is removed, and the two roller structures 50 are used to synchronously drive the cylinder segments to rotate to weld the second cylinder segment to the third cylinder segment; the subsequent cylinder segments are welded in sequence according to the above-mentioned welding process of the second cylinder segment and the third cylinder segment to complete the assembly of the tank body 10.

[0040] Then, the can body 10 is supported by a bracket, and the position of the roller structure 50 is moved so that the can body 10 is placed on one roller structure 50, and the annular cylinder segment 11 of the head portion 20 is placed on another roller structure 50. After the annular cylinder segment 11 of the head portion 20 is aligned with the first cylinder segment and initially fixed, the head portion 20 and the can body 10 are welded by synchronously driving the two roller structures 50 to rotate; the other head portion 20 is placed on the roller structure 50 located on the longitudinal track 41, and the roller structure 50 is moved until the other head portion 20 is aligned with the sixth cylinder segment and initially fixed, and then the three roller structures 50 are synchronously driven to rotate to weld the other head portion 20 to the can body 10, thereby completing the assembly of the single tank.

[0041] For example, after the assembly of the single tanks is completed, the two single tanks can be moved along the longitudinal track 41 to the intersection of the longitudinal track 41 and the transverse track 42 and the two single tanks can be horizontally aligned. The installation position of the bulkhead plate 32 is measured and located using an electronic theodolite with the central axis of the single tank as a reference and marked. A handheld plasma is used to cut along the marked line so that openings 31 are formed on opposite sides of the two single tanks. The bulkhead plate 32 is installed at the opening 31 of one of the single tanks ( Figure 6 , Figure 7 ); Keep the single tank without the bulkhead plate 32 still, and move the single tank with the bulkhead plate 32 along the transverse track 42 until the openings 31 of the two single tanks are aligned ( Figure 8) are welded to obtain a C-type double-body storage tank. By assembling two single tanks with the help of rails, the tank body without the bulkhead plate 32 is kept stationary, and the tank body with the bulkhead plate 32 is moved for assembly, which solves the problem of poor assembly accuracy between tank bodies and also avoids the problem of deformation of the tank body caused by the movement of the tank body without the bulkhead plate 32.

[0042] Specifically, when the single tank is assembled and welded, the slider is located on the longitudinal track 41. The single tank with the bulkhead 32 installed can be supported by a bracket, and the position of the slider can be adjusted so that the slider is adjusted from being clamped on the longitudinal track 41 to being clamped on the transverse track 42, that is, the slider can be moved along the transverse track 42 to dock the two single tanks.

[0043] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for manufacturing a C-type double-body storage tank for LNG shipping, characterized in that: The following steps are involved: S1. A track and a roller structure that can move along the track are set on the platform for tank assembly, and the cylinder section plate and the head plate are pressed according to the design size; S2, assembling and welding a plurality of cylinder segment plates into an annular cylinder segment; using the annular cylinder segment as a tire frame, installing a plurality of head plates on the annular cylinder segment to form a head portion; S3, coaxially placing the two annular cylinder segments on two roller structures respectively, moving the roller structures along the track until the two annular cylinder segments are circumferentially aligned, and then performing preliminary fixing processing on the two annular cylinder segments; then using the roller structure to drive the two annular cylinder segments to rotate synchronously around their axis, and performing circumferential welding on the two annular cylinder segments; S4, according to the processing operation of step S3, assembling and welding a plurality of annular cylinder segments to form a cylindrical tank body; at the same time, placing the annular cylinder segment portion of the head portion on the roller structure, and according to the processing operation of step S3, respectively installing the two head portions at both ends of the tank body to form a first single tank; S5, assembling a second monomer tank according to steps S2 to S4; S6. Openings are cut on the two single tanks respectively, and after the bulkhead is installed at the opening on one of the single tanks, the openings of the two single tanks are aligned and welded to obtain a C-type double-body storage tank.

2. The method for manufacturing a C-type double-body storage tank for LNG shipping according to claim 1, characterized in that: In step S1, the head plate includes an equatorial plate, a temperate plate and a polar plate.

3. The method for manufacturing a C-type double-body storage tank for LNG shipping according to claim 1, characterized in that: In step S1, the track includes a transverse track and a longitudinal track, and the roller structure is arranged on the track through a slider, so that the roller structure can move along the transverse track or the longitudinal track.

4. The method for manufacturing a C-type double-body storage tank for LNG shipping according to claim 1, characterized in that: In step S1, the cylinder segment plate includes a first arc plate made of low temperature resistant alloy steel and a second arc plate made of ordinary carbon steel and used for installation at the corresponding opening position.

5. The method for manufacturing a C-type double-body storage tank for LNG shipping according to claim 4, characterized in that: In step S3, the welding process is to perform spot welding, root welding and submerged arc welding on the two annular cylinder segments in sequence.

6. The method for manufacturing a C-type double-body storage tank for LNG shipping according to claim 4, characterized in that: No base welding is performed between the second arc plates of the two annular cylinder segments.

7. The method for manufacturing a C-type double-body storage tank for LNG shipping according to claim 1, characterized in that: In step S3, the preliminary fixing process is to use a plurality of fasteners to fix the two annular cylinder segments.

8. The method for manufacturing a C-type double-body storage tank for LNG shipping according to claim 1, characterized in that: In step S6, the specific operation of aligning the openings of the two monomer tanks is: keep the monomer tank without the bulkhead plate installed still, and move the monomer tank with the bulkhead plate installed until the openings of the two monomer tanks are aligned.

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