VLOC ship modified methanol fuel cabin and modification method

Abstract

The invention relates to the technical field of VLOC ship modified methanol fuel cabins, and provides a VLOC ship modified methanol fuel cabin and a modification method, which can be matched with the opening sequence and size of a deck, adopt a special treatment method with a deck sheet body for the structure of the methanol fuel cabin, and assemble and reinforce the cabin top deck from the opening sequence of the cabin top deck of the methanol fuel cabin. The problem of integral turning and falling of the inner segment of the deck small-opening integral hoisting cabin and the unmanned cabin segment is solved, the purpose of refitting the VLOC ship methanol fuel cabin at the mooring wharf segment without occupying a dry dock is achieved, the construction portability is improved, the construction environment is improved, and the refitting cost is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of VLOC ship modification of methanol fuel tanks, and in particular to a VLOC ship modification of methanol fuel tanks and a modification method. Background Art

[0002] Very Large Ore Carrier (VLOC) is a type of large ship that transports ore. Its ore carrying capacity often exceeds 200,000 tons. It is one of the large cargo ships that carry ore in international trade. At present, governments of various countries have issued carbon emission reduction decrees, and the International Maritime Organization (IMO) has set carbon emission reduction targets. Carbon emission reduction has been put on the agenda of the international community and is imminent. The fuels used by existing VLOC ships are all traditional carbon (C)-based fuels, which produce a large amount of carbon dioxide (CO2) gas after combustion, and cannot meet the carbon emission reduction requirements and cannot achieve the carbon emission reduction targets set by the International Maritime Organization (IMO). Methanol is in a liquid state at normal temperature and pressure. After combustion, only water (H2O) vapor and carbon dioxide (CO2) gas are produced, and its storage and transportation conditions are ample. Methanol is a new type of carbon-based compound fuel, which is a low-flashpoint flammable and explosive liquid. Traditional ship fuel tanks are not suitable for storing low-flashpoint flammable and explosive methanol fuels, and require special design and modification. Summary of the invention

[0003] One of the purposes of the present invention is to propose a hybrid heave compensation system, which can cooperate with the order and size of deck openings, adopt a special treatment method with deck sheets for the methanol fuel tank structure, assemble in sequence from the openings of the top deck of the methanol fuel tank, and reinforce the top deck while assembling, so as to solve the problem of overall lifting of the sections in the cabin with small deck openings and the overall turning over and placing of the sections in the unmanned cabin, so as to achieve the purpose of modifying the methanol fuel tank of a VLOC ship in sections at the mooring wharf without occupying the dry dock, increase the construction portability, improve the construction environment, and save the modification cost.

[0004] The technical solution of the present invention is as follows:

[0005] A method for converting a methanol fuel tank of a VLOC ship comprises the following steps:

[0006] S100: Make the first cut on the top deck layer of the methanol fuel tank, hoist into the tank bottom along the first cut, and weld with the surrounding structure;

[0007] S200: After the tank bottom is welded back in place, the middle longitudinal bulkhead is hoisted in and welded to the surrounding structure. The deck of the middle longitudinal bulkhead is also spot welded to the top deck layer of the methanol fuel tank at the same time, and then the top deck layer of the methanol fuel tank is repaired;

[0008] S300: Make a second cut on the top deck layer of the methanol fuel tank, hoist the front bulkhead of the methanol tank along the second cut, first assemble the left front bulkhead and the right front bulkhead sections, then hoist the middle front bulkhead of the adjustment section, weld the three sections to the surrounding structure after positioning, and spot weld to the top deck layer of the methanol fuel tank at the same time, and then repair the top deck layer of the methanol fuel tank;

[0009] S400: Make a third cut on the top deck of the methanol fuel tank, hoist into the liquid tank along the third cut and weld with the surrounding structure, and spot weld with the top deck of the methanol fuel tank at the same time, and then fill back the top deck of the methanol fuel tank;

[0010] S500: Make the fourth cut on the top deck layer of the methanol fuel tank, hoist the deck layer along the fourth cut and weld it with the surrounding structure, and make the fourth cut along the joint seam between the port and starboard sides of the deck;

[0011] S600: All structures have been welded and non-destructive tested, the deck house has been hoisted to the top of the methanol fuel tank and the welding has been completed, and the modification of the entire methanol fuel tank has been completed.

[0012] Furthermore, step S100 includes:

[0013] S110: Longitudinal and transverse reinforcement structures are provided around the first cutout, and the width B of the first cutout is consistent with the width of the deck on the mid-longitudinal bulkhead;

[0014] The longitudinal reinforcement structure is installed on the side longitudinal beams on both sides of the first incision, and the two ends extend to the front bulkhead of the engine room and the rear bulkhead of the connected cargo hold respectively. The transverse reinforcement structure is installed between the rear front bulkhead of the methanol tank, the rear bulkhead of the connected cargo hold and the two sets of longitudinal reinforcement structures, and connected to each other to form a rectangular reinforcement frame;

[0015] S120: Then cut along the joint seams of the deck side longitudinal girder, the methanol tank aft bulkhead and the connected cargo hold aft bulkhead.

[0016] Furthermore, the width D of the second incision in step S300 is the same as the deck width of the front bulkhead of the methanol tank, and is cut along the joint seam of the front bulkhead of the methanol tank between the crossbeam and the connected cargo hold rear bulkhead.

[0017] Furthermore, the width A of the third incision in step S400 is the same as the width of the deck on the liquid tank, the height C of the third incision is the same as the height of the inner longitudinal wall of the upper belt of the liquid tank, the third incision is provided with a chamfer R, and is cut along the closing seam of the left liquid tank and the right liquid tank.

[0018] Further, step S200 includes the following steps:

[0019] S210: Draw the bottom line of the methanol fuel tank at the bow, use paint to make a clear mark at the center of the bottom line, and spot weld a baffle with a 75° inclination at the edge of the bottom line;

[0020] S220: Make a clear mark at the center of the bilge with a flat iron, and weld a lifting lug on the front cross section of the bilge. Use the first crane to hang on the lifting lug on the front cross section of the bilge to lift the bilge. Align the rear cross section of the bilge with the longitudinal direction of the first cut and lift it into the bilge.

[0021] S230: The bilge is turned 90° in the cabin, and the second crane is hung on the rear cross-section lifting lug of the bilge to lift it upwards, and then turned over longitudinally;

[0022] S240: The first crane and the second crane are lowered simultaneously until they are close to the height of the baffle. After confirming that the flat iron of the bilge coincides with the paint mark on the center line of the landing line, the bilge continues to be lowered, guided by the inclined surface of the bulkhead, the inclined surface of the port longitudinal bulkhead, the inclined surface of the starboard longitudinal bulkhead and the baffle, until the bilge is in place.

[0023] Furthermore, step S500 includes:

[0024] S510: Draw the fourth cut opening line on the top deck layer of the methanol fuel tank;

[0025] S520: The fourth cut is drawn from the stern to the deck joint of the methanol tank aft bulkhead, and the bow is drawn from the deck joint of the second cut;

[0026] S530: The fourth cut is made from the midship to the first cut deck plating seam, from the side to the third cut deck plating seam and to the inner shell deck plating seam, along the marking position;

[0027] S540: First make the fourth cut on the left chord, and then hoist the left deck along the fourth cut on the left chord and weld it to the surrounding structure;

[0028] Then make the fourth cut on the starboard side, lift in the right deck along the fourth cut on the right chord and weld it to the surrounding structure to complete the deck layer replacement.

[0029] Another purpose of this embodiment is to provide a VLOC ship modified methanol fuel tank, including a left tank, a right tank, a bilge, a middle longitudinal bulkhead, a front bulkhead of a methanol tank, a left liquid tank, a right liquid tank, a deck layer, a deckhouse and an empty tank, wherein the middle longitudinal bulkhead is located between the left tank and the right tank. The empty tanks have two and are respectively arranged on the side opposite to the left tank and the right tank, the bilge bottom is connected to the two empty tanks at the same time, the middle longitudinal bulkhead divides the methanol fuel tank into two independent liquid tanks on the left and right, the deckhouse is an independent cabin for protecting methanol auxiliary equipment and supply equipment, the front bulkhead of the methanol tank is divided into three sections: the left front bulkhead, the right front bulkhead and the middle front bulkhead, the deck layer is divided into two sections: the left deck and the right deck, and manholes are provided on the two inner walls opposite to the left tank and the right tank.

[0030] Furthermore, an inner bottom plate is provided at the bottom of the cabin bottom, two empty cabins are connected to the two sides of the inner bottom plate, and both the left cabin and the right cabin have inner longitudinal walls.

[0031] Furthermore, the deckhouse is divided into a number of independent compartments by vertical bulkheads;

[0032] The independent compartment includes an auxiliary equipment room, a fuel preparation room, a discharge tank and a methanol daily cabinet. The discharge tank is located on the side of the fuel preparation room close to the methanol daily cabinet. The methanol daily cabinet is protected by an isolation cabin, and the isolation cabin is connected to the fuel preparation room through an opening.

[0033] The working principle and beneficial effects of the present invention are:

[0034] A method for refitting methanol fuel tanks at existing VLOC ship mooring docks and hoisting sections in the cabin as a whole is provided. According to the order and size of deck openings, a special treatment method with deck sheets is adopted for the methanol fuel tank structure, and the openings of the top deck of the methanol fuel tank are assembled in sequence, and the top deck is reinforced while being assembled, which solves the problem of hoisting the sections in the cabin as a whole with small deck openings and turning over and placing the unmanned cabin sections as a whole, and achieves the purpose of refitting VLOC ship methanol fuel tanks in sections at the mooring dock without occupying the dry dock, which increases the portability of construction, improves the construction environment, saves the cost of modification, and provides technical support for the modification of methanol fuel tanks for existing VLOC ships. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0036] Figure 1 This is the section division diagram of the methanol fuel tank;

[0037] Figure 2 is the cross-sectional view AA;

[0038] Figure 3 This is a schematic diagram of the front bulkhead of the methanol tank;

[0039] Figure 4 This is the deck opening diagram;

[0040] Figure 5 Assembly diagram for the bilge, showing the bilge hanging man;

[0041] Figure 6 This is a diagram of the bilge assembly, showing the bilge turning over after turning;

[0042] Figure 7 This is a diagram of the bilge assembly, showing the bilge's position after turning over;

[0043] Figure 8 This is the bilge assembly drawing, showing the bilge position check;

[0044] Fig. 9 It is the assembly flow chart;

[0045] Fig.10This is a diagram of the openings in the bulkhead of the connected cargo hold, which are arranged symmetrically on the port and starboard sides.

[0046] In the figure: 11, deck layer; 12, deck house; 13, reinforcement structure; 14, first cut; 15, second cut; 16, third cut; 17, fourth cut; 2, bilge; 3, middle longitudinal bulkhead; 4, front bulkhead of methanol tank; 41, left front bulkhead; 42, right front bulkhead; 43, middle front bulkhead; 45, rear bulkhead of methanol tank; 46, front cross section of bilge; 47, rear cross section of bilge; 48, front bulkhead of engine room; 5, methanol fuel tank; 61, left liquid tank; 62, right liquid tank; 63. Horizontal girder; 64. Straight ladder; 65. Outer plate; 66. Port longitudinal bulkhead; 67. Starboard longitudinal bulkhead; 71. Port hold; 72. Right hold; 73. Port empty hold; 74. Right empty hold; 75. Inner longitudinal wall; 76. Inner bottom plate; 81. Auxiliary equipment room; 82. Fuel preparation room; 83. Drainage tank; 84. Isolation tank; 85. Methanol daily cabinet; 91. Rear bulkhead of connected cargo hold; 92. First crane; 93. Second crane; 95. Process hole; 96. Baffle; 97. Inclined ladder. DETAILED DESCRIPTION

[0047] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0048] Embodiment 1

[0049] like Figure 1-10 As shown, a modification method for a VLOC ship to modify a methanol fuel tank 5 is provided. According to the order and size of the deck openings, the methanol fuel tank 5 structure is processed by a special method with a deck sheet. The methanol fuel tank 5 structure is assembled sequentially from the methanol fuel tank 5 (divided into a left methanol tank and a right methanol tank by a middle longitudinal bulkhead 3) through the top deck openings by a crane. The existing VLOC ship is modified at the mooring wharf, and the purpose of reinforcing the top deck openings while assembling is achieved. The method is suitable for all platforms, ships and marine structures, and is completed through the following steps.

[0050] Specifically, the steps include:

[0051] S100: Use the dock crane to sequentially open the top deck of the methanol fuel tank 5 to assemble the methanol fuel tank 5 structure, draw the opening line of the first incision 14 on the top deck layer 11 of the methanol fuel tank 5, draw the line from the stern of the first incision 14 to the deck joint of the methanol tank rear bulkhead 45, draw the line from the bow to the deck joint of the connected cargo hold bulkhead, and draw lines to the port and starboard sides respectively with the middle longitudinal girder of the deck as the baseline.

[0052] A first incision 14 is made on the top deck layer 11 of the methanol fuel tank 5, and the tank is hoisted into the tank bottom 2 along the first incision 14 and welded to the surrounding structure;

[0053] Step S100 includes:

[0054] S110: longitudinal reinforcement structures 13 and transverse reinforcement structures 13 are arranged around the first cutout 14, and the width B of the first cutout 14 is consistent with the width of the deck on the middle longitudinal bulkhead 3; the width B of the first cutout 14 = 6100 mm is consistent with the width of the deck on the middle longitudinal bulkhead 3, and the left and right marking lines are 150 mm away from the left and right side longitudinal beams of the deck.

[0055] The longitudinal reinforcement structure 13 is installed on the side longitudinal beams on both sides of the first cutout 14, and the two ends extend to the front bulkhead 48 of the engine room and the connected rear bulkhead 91 of the cargo hold respectively. The transverse reinforcement structure 13 is installed between the rear bulkhead 45 of the methanol tank, the connected rear bulkhead 91 of the cargo hold and the two sets of longitudinal reinforcement structures 13, and connected to each other to form a rectangular reinforcement frame;

[0056] The longitudinal reinforcement structure 13 and the transverse reinforcement structure 13 are made of T300x20 / 900x20 high-strength steel T-profiles. The transverse T-profile is installed between the rear bulkhead 45 of the methanol tank, the connected cargo hold rear bulkhead 91 and the two longitudinal T-profiles, and are interconnected to form a rectangular reinforcement frame.

[0057] S120: Then, a first incision 14 is made along the marked position, specifically, along the joint seam between the deck side longitudinal girder and the methanol tank rear bulkhead 45 and the connected cargo tank rear bulkhead 91.

[0058] S210: Draw the bottom line of the tank 2 at the bow of the methanol fuel tank 5, use paint to make a clear mark at the center of the bottom line, and spot weld a baffle 96 with a 75° inclination at the edge of the bottom line;

[0059] S220: Make a clear mark at the center of the bilge 2 with a flat iron, and weld a lifting lug on the front cross section 46 of the bilge. Use the first crane 92 to hang on the lifting lug on the front cross section 46 of the bilge to lift the bilge 2. Align the rear cross section 47 of the bilge with the longitudinal direction of the first cutout 14 and lift it into the bilge.

[0060] S230: the bilge 2 is turned 90 degrees in the cabin, and the second crane 93 is used to hang on the lifting lug of the rear cross section 47 of the bilge and lift it upward, and then turn it over longitudinally;

[0061] S240: The first crane 92 and the second crane 93 are lowered simultaneously until they are close to the height of the baffle 96. After confirming that the flat iron of the bilge 2 coincides with the paint mark on the center line of the drop line, the bilge 2 is continued to be lowered, guided by the inclined surface of the rear bulkhead 45 of the methanol tank, the inclined surface of the port longitudinal bulkhead 66, the inclined surface of the starboard longitudinal bulkhead 67 and the baffle 96, until the bilge 2 is in place. Figure 5-8 Bilge 2 assembly diagram shown.

[0062] S200: hoisting the bilge 2 from the first incision 14 to weld it with the surrounding structure. After the bilge 2 is welded back in place, hoisting the middle longitudinal bulkhead 3 to weld it with the surrounding structure. The deck of the middle longitudinal bulkhead 3 is also spot welded with the top deck layer 11 of the methanol fuel tank 5 at the same time. Then, the top deck layer 11 of the methanol fuel tank 5 is repaired.

[0063] S300: Make a second incision 15 on the top deck layer 11 of the methanol fuel tank 5. Specifically, draw an opening line of the second incision 15 on the top deck layer 11 of the methanol fuel tank 5. The left and right marking lines of the second incision 15 are at a distance from the inner shell deck joint, and the bow marking line is at a distance from the deck joint of the connected cargo hold rear bulkhead 91. The width of the second incision 15 D=2200mm coincides with the deck width of the methanol tank front bulkhead 4. The second incision 15 is made between the crossbeam and the connected cargo hold rear bulkhead 91, along the closing seam of the methanol tank front bulkhead 4, i.e., the marking position.

[0064] Then, the front bulkhead 4 of the methanol tank is hoisted in along the second incision 15, and the two sections of the left front bulkhead 41 and the right front bulkhead 42 are assembled first, and then the middle front bulkhead 43 of the adjustment section is hoisted in. After the three sections are positioned, they are welded to the surrounding structure and spot welded to the top deck layer 11 of the methanol fuel tank 5 at the same time, and then the top deck layer 11 of the methanol fuel tank 5 is repaired.

[0065] S400: Draw the opening line of the third cut 16 on the top deck layer 11 of the methanol fuel tank 5. The stern line of the third cut 16 is 500mm away from the rear bulkhead of the liquid tank, and the bow line is drawn to the joint of the deck of the connected cargo hold bulkhead. The width of the third cut 16 is A=5500mm, which is consistent with the width of the deck on the liquid tank, and the height is C=13000mm, which is consistent with the height of the inner longitudinal wall 75 on the liquid tank. The third cut 16 is chamfered, and the chamfer R=1000mm.

[0066] A third incision 16 is made along the marked position on the top deck layer 11 of the methanol fuel tank 5, and the liquid tank is hoisted in along the third incision 16 for welding with the surrounding structure, and spot welding is also performed with the top deck layer 11 of the methanol fuel tank 5 at the same time, and then the top deck layer 11 of the methanol fuel tank 5 is repaired;

[0067] First, open the third incision 16 on the left chord, and hoist the left liquid tank 61 along the third incision 16 on the left chord to weld it with the surrounding structure; then open the third incision 16 on the starboard side, and hoist the right liquid tank 62 along the third incision 16 on the right chord to weld it with the surrounding structure to complete the liquid tank hoisting.

[0068] The width A of the third incision 16 in step S400 is the same as the width of the deck on the liquid tank, the height C of the third incision 16 is the same as the height of the inner longitudinal wall 75 of the liquid tank, the third incision 16 is provided with a chamfer R, and is cut along the joint seam of the left liquid tank 61 and the right liquid tank 62, and is symmetrically distributed on the left and right sides.

[0069] S500: a fourth incision 17 is made on the top deck layer 11 of the methanol fuel tank 5, the deck layer 11 is hoisted in along the fourth incision 17 and welded to the surrounding structure, and the fourth incision 17 is cut along the joint seam between the port side and the starboard side of the deck;

[0070] Step S500 includes:

[0071] S510: Draw an opening line of the fourth incision 17 on the top deck layer 11 of the methanol fuel tank 5;

[0072] S520: The fourth cut 17 is drawn from the stern to the deck joint 45 of the methanol tank aft bulkhead, and the bow is drawn to the deck joint 15 of the second cut;

[0073] S530: The fourth cut 17 is made from the midship to the first cut 14 deck plating seam, from the side to the third cut 16 deck plating seam and to the inner shell deck plating seam, and the fourth cut 17 is made along the marking position;

[0074] S540: First, open the fourth cut 17 of the left chord, and hoist the left deck along the fourth cut 17 of the left chord to weld it with the surrounding structure;

[0075] Then, the fourth incision 17 is opened on the starboard side, and the right deck is hoisted in along the fourth incision 17 on the right chord to be welded with the surrounding structure, so that the replacement of the deck layer 11 is completed.

[0076] S600: All structures have been welded and non-destructive tested, the deck house 12 has been hoisted to the top of the methanol fuel tank 5 and the welding has been completed, and the modification of the entire methanol fuel tank 5 has been completed.

[0077] Embodiment 2

[0078] A methanol fuel tank 5 converted into a VLOC ship mainly comprises a left tank 71, a right tank 72, a bilge 2, a middle longitudinal bulkhead 3, a methanol tank front bulkhead 4, a left liquid tank 61, a right liquid tank 62, a deck layer 11, a deck house 12 and an empty tank.

[0079] The methanol fuel tank 5 is between the front bulkhead 48 of the engine room and the rear bulkhead 91 of the connected cargo hold. The front bulkhead 4 of the methanol tank is close to the rear bulkhead 91 of the connected cargo hold. A temporary stairway is arranged in the connected cargo hold, and two process holes 95 are opened on the left and right sides of the rear bulkhead 91 of the connected cargo hold. The size of the process hole 95 is bxhxr=1000mmx1800mmx150mm. The edge is u=50mm away from the bulkhead supporting material and v=200mm away from the deck. The upper and lower edges of the process hole 95 are u=50mm away and reinforced with frame materials of the same size as the bulkhead. The process hole 95 is connected with the methanol fuel tank 5 to facilitate the passage of personnel during the modification. Ventilation, lighting, engineering electricity and gas, etc. are arranged on the side of the methanol tank. Figure 5-8 and Fig.10 The opening diagram of the connected cargo hold bulkhead is shown in the figure.

[0080] like Figure 1and Figure 2 As shown, the middle longitudinal bulkhead 3 is located between the left tank 71 and the right tank 72, dividing the methanol fuel tank 5 into two independent liquid tanks on the left and right. The middle longitudinal bulkhead 3 is a longitudinal structure with a deck width of B=6100mm, which is connected to the rear bulkhead 45 of the methanol tank backwards and to the front bulkhead 4 of the methanol tank forwards, connected to the front bulkhead 48 of the engine room through the rear bulkhead 45 of the methanol tank, and connected to the rear bulkhead 91 of the connected cargo hold through the front bulkhead 4 of the methanol tank.

[0081] There are two empty tanks, which are respectively arranged on the side opposite to the left tank 71 and the right tank 72. The bottom 2 is connected to the two empty tanks at the same time. The middle longitudinal bulkhead 3 divides the methanol fuel tank 5 into two independent liquid tanks on the left and right. The deck house 12 is an independent cabin for protecting methanol auxiliary equipment and supply equipment. The front bulkhead 4 of the methanol tank is divided into three sections: the left front bulkhead 41, the right front bulkhead 42 and the middle front bulkhead 43. The deck layer 11 is divided into two sections: the left deck and the right deck. Manholes are provided on the two inner walls opposite to the left tank 71 and the right tank 72.

[0082] like Figures 1 to 3 As shown, the front bulkhead 4 of the methanol tank is a transverse structure with a deck width of D=2200mm, connected to the port longitudinal bulkhead 66 of the methanol fuel tank 5 to the left, and connected to the starboard longitudinal bulkhead 67 of the methanol fuel tank 5 to the right. The front bulkhead 4 of the methanol tank is divided into three sections: the left front bulkhead 41, the right front bulkhead 42 and the middle front bulkhead 43, and the middle front bulkhead 43 is set as an adjustment section.

[0083] like Figure 1 and Figure 2 As shown, the liquid tank is a structure with a deck width of A = 5500mm, a deck chamfer of R = 1000mm and an inner longitudinal wall 75 height of C = 13000mm, and is installed in the side tank of the methanol fuel tank, which is connected to the methanol fuel tank 5. The liquid tank is divided into two sections, the left liquid tank 61 and the right liquid tank 62.

[0084] The above parameters are all actual ship operation data, which are determined according to the deck structure layout, bottom segment size and lifting requirements of different ship types (especially B and D). This embodiment is only for optimization and example.

[0085] like Figure 1 As shown in the segmentation diagram of the methanol fuel tank 5, the tank bottom 2 is installed on the inner bottom plate 76 at the bottom, and two empty tanks are connected on both sides of the inner bottom plate 76. The left tank 71 and the right tank 72 both have inner longitudinal walls, and a manhole is opened in the empty tank on the back of the inner longitudinal wall, so that the empty tank of the methanol fuel tank 5 is surrounded by protection, which is convenient for arranging methanol gas-liquid detectors to detect leakage of the methanol fuel tank 5.

[0086] The deck house 12 is divided into a number of independent compartments by vertical bulkheads;

[0087] The independent compartment includes an auxiliary equipment room 81, a fuel preparation room 82, a discharge tank 83 and a methanol daily cabinet 85 (or a methanol daily cabinet). The discharge tank 83 is located on the side of the fuel preparation room 82 close to the methanol daily cabinet 85. The methanol daily cabinet 85 is protected by an isolation cabin 84, and the isolation cabin 84 is connected to the fuel preparation room 82 through an opening.

[0088] The present invention provides a deck opening sequence and size, and adopts a deck sheet processing method for the methanol fuel tank 5 structure, closes the deck sheets in sections, closes the sections while opening holes, and reinforces the deck openings, and then opens the next section opening, and completes the section closing in a cycle. Conventional closing is to open holes once, hoist the whole at one time or hoist the sheets in multiple times, which is significantly different from and improved on conventional closing. Specifically, the methanol fuel tank 5 is assembled in sequence from the opening sequence of the top deck, and the top deck is reinforced while being assembled, so as to achieve the purpose of modifying the methanol fuel tank 5 of the VLOC ship in sections at the mooring wharf without occupying the dry dock. Compared with the prior art of VLOC ship entering dry dock for transformation, the deck of the methanol fuel tank 5 is directly cut off at one time, which occupies a long dry dock period, has great limitations on the selection of dry dock conditions, and has the characteristics of high transformation cost, and has absolute advantages.

[0089] Moreover, the existing technology is to directly cut off the deck of the methanol fuel tank 5 at one time, and the bottom 2 of the tank is divided into two parts, which are hoisted and placed in place with the assistance of personnel. The present invention also realizes the segmented transformation of the methanol fuel tank 5 at the existing VLOC ship wharf, and solves the problem of hoisting the cabin segments with a small deck opening as a whole and turning over and placing the unmanned cabin segments as a whole.

[0090] In addition, the prior art directly opens a process hole 95 and overlaps the temporary ladder in the methanol fuel tank 5. After the methanol fuel tank 5 is modified, the temporary ladder is removed and the process hole 95 is blocked, which cannot achieve the integrity of the coating of the methanol fuel tank 5. The present invention opens a process hole 95 in the bulkhead of the connected cargo tank, which ensures the safety of personnel and the integrity of the coating of the methanol fuel tank 5 and improves the construction environment.

[0091] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for converting a methanol fuel tank (5) of a VLOC ship, characterized in that: The steps include: S100: a first incision (14) is made on the top deck layer (11) of the methanol fuel tank (5), the incision is hoisted into the tank bottom (2) along the first incision (14), and the incision is welded to the surrounding structure; S200: After the tank bottom (2) is welded back into place, the middle longitudinal bulkhead (3) is hoisted in and welded to the surrounding structure. The deck of the middle longitudinal bulkhead (3) is also spot welded to the top deck layer (11) of the methanol fuel tank (5) at the same time. Then, the top deck layer (11) of the methanol fuel tank (5) is repaired. S300: a second incision (15) is made on the top deck layer (11) of the methanol fuel tank (5), and the front bulkhead (4) of the methanol tank is hoisted in along the second incision (15). The left front bulkhead (41) and the right front bulkhead (42) are first assembled, and then the middle front bulkhead (43) of the adjustment segment is hoisted in. After the three segments are positioned, they are welded to the surrounding structure and spot welded to the top deck layer (11) of the methanol fuel tank (5) at the same time, and then the top deck layer (11) of the methanol fuel tank (5) is repaired; S400: a third incision (16) is made on the top deck layer (11) of the methanol fuel tank (5), and the liquid tank is hoisted in along the third incision (16) and welded to the surrounding structure, and spot welded to the top deck layer (11) of the methanol fuel tank (5) at the same time, and then the top deck layer (11) of the methanol fuel tank (5) is repaired; S500: a fourth incision (17) is made on the top deck layer (11) of the methanol fuel tank (5), and the deck layer (11) is hoisted in along the fourth incision (17) and welded to the surrounding structure; S600: All structures are welded and non-destructively tested, the deck house (12) is hoisted to the top of the methanol fuel tank (5) and the welding is completed, and the modification of the entire methanol fuel tank (5) is completed.

2. A method for converting a VLOC ship into a methanol fuel tank (5) according to claim 1, characterized in that: Step S100 includes: S110: a longitudinal reinforcement structure (13) and a transverse reinforcement structure (13) are arranged around the first cutout (14), and a width B of the first cutout (14) is consistent with a width of a deck on the middle longitudinal bulkhead (3); The longitudinal reinforcement structure (13) is installed on the side longitudinal beams on both sides of the first cutout (14), and the two ends extend to the front bulkhead (48) of the engine room and the rear bulkhead (91) of the connected cargo hold respectively; the transverse reinforcement structure (13) is installed between the rear front bulkhead (45) of the methanol tank, the rear bulkhead (91) of the connected cargo hold and the two sets of longitudinal reinforcement structures (13), and they are connected to each other to form a rectangular reinforcement frame; S120: Then cut along the joint seams of the deck side longitudinal girder, the methanol tank rear bulkhead (45), and the connected cargo tank rear bulkhead (91).

3. The method for converting a VLOC ship into a methanol fuel tank (5) according to claim 1, characterized in that: Step S200 includes the following steps: S210: A bottom line (2) is drawn at the bow of the methanol fuel tank (5), the center line of the bottom line is clearly marked with paint, and a baffle (96) with an inclination angle of а=75° is spot welded at the edge of the bottom line; S220: A flat iron is used to make a clear mark at the center of the bilge (2), and a lifting lug is welded on the front cross section (46) of the bilge. The bilge (2) is lifted up by using a first crane (92) to hang on the lifting lug of the front cross section (46) of the bilge. The rear cross section (47) of the bilge is aligned with the longitudinal direction of the first cutout (14) and is lifted into the bilge. S230: The cabin bottom (2) is turned 90 degrees in the cabin, and the second crane (93) is hung on the lifting lug of the rear cross section (47) of the cabin bottom and lifted upward, and then turned over longitudinally; S240: The first crane (92) and the second crane (93) are simultaneously lowered to approach the height of the baffle (96). After confirming that the flat iron of the bilge (2) coincides with the paint mark on the center line of the landing line, the bilge (2) is continued to be lowered, and guided downward by the inclined surface of the bulkhead (45), the inclined surface of the port longitudinal bulkhead (66), the inclined surface of the starboard longitudinal bulkhead (67) and the baffle (96), until the bilge (2) is in place.

4. A method for converting a VLOC ship into a methanol fuel tank (5) according to claim 2, characterized in that: The width D of the second incision (15) in step S300 is the same as the deck width of the front bulkhead (4) of the methanol tank, and is cut along the joint seam of the front bulkhead (4) of the methanol tank between the crossbeam and the connected cargo hold rear bulkhead (91).

5. The method for converting a VLOC ship into a methanol fuel tank (5) according to claim 1, characterized in that: The width A of the third incision (16) in step S400 is the same as the width of the deck on the liquid tank, the height C of the third incision (16) is the same as the height of the inner longitudinal wall (75) of the upper belt of the liquid tank, and the third incision (16) is provided with a chamfer R and is cut along the joint seam of the left liquid tank (61) and the right liquid tank (62).

6. A method for converting a VLOC ship into a methanol fuel tank (5) according to claim 1, characterized in that: Step S500 includes: S510: Draw an opening line of the fourth incision (17) on the top deck layer (11) of the methanol fuel tank (5); S520: The fourth cut (17) is marked from the stern to the deck joint of the methanol tank aft bulkhead (45), and the bow is marked from the deck joint of the second cut (15); S530: The fourth cut (17) is from the midship to the first cut (14) deck plate seam, from the side to the third cut (16) deck plate seam and to the inner shell deck plate seam, and the fourth cut (17) is made along the marked position; S540: First, make the fourth cut (17) on the left chord, and then hoist the left deck along the fourth cut (17) on the left chord and weld it to the surrounding structure; Then, the fourth incision (17) is opened on the starboard side, and the right deck is hoisted in along the fourth incision (17) on the right chord to be welded with the surrounding structure, thereby completing the replacement of the deck layer (11).

7. A VLOC ship modified methanol fuel tank (5) according to any one of claims 1 to 6, characterized in that: The invention comprises a left tank (71), a right tank (72), a bilge (2), a middle longitudinal bulkhead (3), a front bulkhead (4) of a methanol tank, a left liquid tank (61), a right liquid tank (62), a deck layer (11), a deck house (12) and an empty tank. The middle longitudinal bulkhead (3) is located between the left tank (71) and the right tank (72), and divides the methanol fuel tank (5) into two left and right independent liquid tanks. The empty tank has two, which are respectively arranged on the opposite sides of the left tank (71) and the right tank (72). The bottom (2) is connected to two empty tanks at the same time. The middle longitudinal bulkhead (3) divides the methanol fuel tank (5) into two independent liquid tanks on the left and right. The deck house (12) is an independent cabin for protecting methanol auxiliary equipment and supply equipment. The front bulkhead (4) of the methanol tank is divided into three sections, namely, the left front bulkhead (41), the right front bulkhead (42) and the middle front bulkhead (43). The deck layer (11) is divided into two sections, namely, the left deck and the right deck. Manholes are provided on the two inner walls opposite to each other of the left cabin (71) and the right cabin (72).

8. A VLOC ship modified methanol fuel tank (5) according to the method of claim 7, characterized in that: The bottom of the cabin bottom (2) is provided with an inner bottom plate (76), and two empty cabins are respectively connected on both sides of the inner bottom plate (76), and the left cabin (71) and the right cabin (72) both have inner longitudinal walls.

9. A VLOC ship modified methanol fuel tank (5) according to the method of claim 7, characterized in that: The deckhouse (12) is divided into a plurality of independent compartments by vertical bulkheads; The independent cabin comprises an auxiliary equipment room (81), a fuel preparation room (82), a discharge cabin (83) and a methanol daily cabinet (85). The discharge cabin (83) is located on the side of the fuel preparation room (82) close to the methanol daily cabinet (85). The methanol daily cabinet (85) is protected by an isolation cabin (84), and the isolation cabin (84) is connected to the fuel preparation room (82) through an opening.

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