A method for hoisting and assembling a gas combustion unit (GCU) of a large LNG carrier

Abstract

A hoisting assembly method of a gas combustion unit GCU of a large LNG transport ship, a GCU exhaust pipe body is divided into an upper exhaust pipe and a lower exhaust pipe, and the two sections are connected through a sleeve. The two ends of the upper exhaust pipe and the lower exhaust pipe are welded with eye plates, the inside of the upper exhaust pipe is provided with a reinforcing support, and the upper exhaust pipe and the adjacent chimney section are pre-assembled. The lower exhaust pipe and the adjacent section are pre-assembled, after the pre-assembly is completed, a temporary reinforcing structure is welded at the eye plate at the bottom of the upper exhaust pipe and the eye plate at the top of the lower exhaust pipe, and the upper exhaust pipe and the lower exhaust pipe are folded. The lower part of the poop is installed on the deck surface, after the lower part of the poop is installed in place, the upper part of the poop and the lower part of the poop are folded. The present application avoids the limitation of the transportation capacity of the factory vehicles, reduces the transportation difficulty in the factory, the two exhaust pipe sections are pre-assembled with the adjacent sections, the total assembly hoisting frequency is reduced, and the production efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of shipbuilding and design, and specifically relates to a method for hoisting and assembling a gas combustion unit (GCU) for a large LNG carrier. Background Technology

[0002] In the gas combustion chambers (CCHs) used in large LNG carriers, ALFA LAVAL's CCHs are relatively small compared to others in the industry, measuring 9767mm in height and 3657mm in diameter. In contrast, KANGRIM's CCHs are over 14000mm in height and nearly 4000mm in diameter. Currently, the lifting capabilities of large domestic shipyards are generally insufficient for the overall installation. Our shipyard has a 175,000 m³... 3 The GCU installed on large LNG carriers is a product of ALFA LAVAL.

[0003] Due to the enormous size of the GCU, the corresponding EXS (Extended Storage System) also increases in size. The EXS of this ship's GCU has a total height of 16400mm, an outer diameter of 3700mm, a wall thickness of 10mm, and weighs over 15 tons. Therefore, lifting and installation face challenges in terms of lifting capacity and installation precision control. The height from the top of the sterncastle to the baseline of large LNG carriers is generally around 51000mm or even higher. Lifting the EXS after the sterncastle installation will increase the lifting height by 25000mm, which is beyond the capabilities of ordinary shipyards to achieve a lifting height of over 76000mm.

[0004] In addition, the large overall size, high precision requirements, and difficulty in repairing damage to the exhaust pipes and combustion chambers present certain challenges to construction, mainly in the following aspects:

[0005] The exhaust pipe is large in size, with a diameter of up to 3720mm, which exceeds the size range of ordinary ship exhaust pipes. The application of such a large exhaust pipe in China is also a completely new field. The length reaches 16.4m, exceeding the 10-meter transportation limit of large vehicles in shipyards.

[0006] The minimum clearance between the combustion chamber and the exhaust pipe is 21.5mm. To ensure the normal operation of the hoisting work, the theoretical cylindricity requirement of the inner wall of the exhaust pipe is -21mm, and the allowable deformation of the relative radius is 1.1%. Considering the clearance requirements for hoisting, the actual cylindricity must be higher than the above requirements.

[0007] To ensure the installation of the combustion chamber top support, the clearance at the top of the combustion chamber needs to be between 15.5mm and 32.5mm. Therefore, the cylindricity in the combustion chamber top support installation area needs to be between -5.5mm and +11mm.

[0008] In addition, the sensor that monitors the combustion status is located on the exhaust pipe, so there are strict requirements for the relative position of the combustion chamber and the exhaust pipe.

[0009] In summary, we need to consider a reasonable and effective method for hoisting and assembling the combustion device to solve the above problems, while meeting the requirements of construction equipment, reducing on-site construction difficulties, and improving the efficiency and economy of shipbuilding. Summary of the Invention

[0010] To address the aforementioned problems, this invention provides a method for hoisting and assembling the gas combustion unit (GCU) of a large LNG carrier. The aim is to reduce on-site construction difficulty and improve the efficiency and economy of shipbuilding while meeting the requirements of construction equipment. The technical solution adopted is as follows:

[0011] A method for hoisting and assembling a gas combustion unit (GCU) for a large LNG carrier. The main body of the GCU exhaust pipe adopts a two-section design, namely an upper exhaust pipe and a lower exhaust pipe, which are connected by a sleeve. The sleeve is pre-installed at the bottom of the upper exhaust pipe.

[0012] Both ends of the upper and lower exhaust pipes are welded with eye plates, with two eye plates at each end, and the two eye plates are symmetrically arranged. The upper exhaust pipe consists of an upper exhaust section and an adjacent lower exhaust section, and the upper exhaust pipe is equipped with reinforcing supports inside.

[0013] The lower exhaust pipe is designed independently, and a reinforcing support is installed in advance at the connection point at the top of the lower exhaust pipe.

[0014] The lower section of the sterncastle is located below the installation deck and includes the GCU fan and housing. The housing is a hull structure with a ventilation opening on the top. After the lower section of the sterncastle is installed, a hand-operated hoist and a top screw device are pre-installed on the installation deck.

[0015] The specific steps for joining the parts are as follows:

[0016] S1: Under the ship, connect the upper exhaust section with the lower exhaust section to form the upper exhaust pipe.

[0017] S2: After the lower section of the sterncastle is installed in place, the lower exhaust pipe is hoisted onto the ship, installed with the lower section of the sterncastle, and then sealed.

[0018] S3: The upper exhaust pipe is hoisted onto the ship and connected to the lower exhaust pipe through a sleeve. After the connection, temporary reinforcing structures are welded at the eye plate at the bottom of the upper exhaust pipe and at the eye plate at the top of the lower exhaust pipe.

[0019] S4: Transport the GCU combustor from the top of the upper exhaust pipe downwards. The vertical lifting distance is about 10m. During the lifting process, when it is 2 meters away from the bottom deck, use the GCU combustor lifting eye plate and hand chain hoist as traction to assist in the placement of the GCU combustor.

[0020] After the GCU combustor is positioned, its position is adjusted using the deck-mounted screw device to temporarily fix it to the installation deck. The lifting gear is then detached, and the top clearance of the GCU combustor is adjusted using the screw device on the installation deck. Four sets of top supports are then installed on the top of the GCU combustor. The four sets of top supports are evenly spaced along the circumference of the GCU combustor. Each set contains two symmetrically arranged top supports with a gap between them. The center of the two top supports forms a 30° angle with the line connecting the circles of the GCU combustor.

[0021] By arranging four sets of a total of eight top supports along the circumference of the top of the GCU combustion chamber, the displacement caused by the ship's swaying or the deformation caused by the thermal expansion of the combustion chamber is absorbed.

[0022] S5: After all sections are closed, remove the temporary reinforcing structure and the reinforcing supports inside the upper and lower exhaust pipes.

[0023] Furthermore, in the above-mentioned method for hoisting and assembling a gas combustion unit (GCU) for a large LNG carrier, the sleeve length is 200mm.

[0024] Furthermore, in the above-mentioned method for hoisting and assembling a gas combustion unit (GCU) for a large LNG carrier, the upper exhaust pipe is 6.4 meters long and the lower exhaust pipe is 10 meters long.

[0025] Furthermore, in the above-mentioned method for hoisting and assembling a gas combustion unit (GCU) for a large LNG carrier, the eye plate is welded to the reinforcing structure of the insulating frame.

[0026] Furthermore, in the above-mentioned method for hoisting and assembling the gas combustion unit (GCU) of a large LNG carrier, the upper exhaust pipe is equipped with a thickened insulating frame.

[0027] Furthermore, in the above-mentioned method for hoisting and assembling a gas combustion unit (GCU) for a large LNG carrier, the vertical hoisting distance of the combustion chamber is 16.6m.

[0028] The above-mentioned method for hoisting and assembling a gas combustion unit (GCU) for a large LNG carrier takes a further step by using a combustion chamber hoisting eyeplate and a hand-operated hoist as traction to assist in the placement of the combustion chamber at a height of 2 meters from the bottom deck.

[0029] Furthermore, in the above-mentioned method for hoisting and assembling a gas combustion unit (GCU) for a large LNG carrier, before the upper exhaust pipe is pre-assembled with the adjacent chimney in sections, the exhaust pipe support and sensor cable bracket are installed on the upper exhaust pipe.

[0030] The above-mentioned method for hoisting and assembling a gas combustion unit (GCU) for a large LNG carrier further involves installing the exhaust pipe support, pressure detection pipeline, through-chamber components, maintenance manhole cover, and various sensor bases onto the lower exhaust pipe before pre-assembling the lower exhaust pipe with adjacent sections.

[0031] Furthermore, in the above-mentioned method for hoisting and assembling a gas combustion unit (GCU) for a large LNG carrier, the cylindricity of the upper exhaust pipe is -10mm to +10mm, and the cylindricity of the welded joint at the top of the lower exhaust pipe is -5.5mm to +11mm.

[0032] The gas combustion device hoisting and assembly method of the present invention avoids the limitation of the vehicle transportation capacity in the factory through a two-section design, reducing the difficulty of transportation in the factory; at the same time, the two exhaust pipe sections are pre-assembled with adjacent sections, reducing the number of hoisting operations for the whole assembly and improving production efficiency.

[0033] The design of the process eyeplate ensures the integrity of the exhaust pipe body and coating during the later removal of the sealing structure, reducing unnecessary recoating processes and material loss. The modular design of the exhaust pipe allows for overall hoisting, reducing on-site workload during assembly and improving work efficiency.

[0034] Accurate control of the cylindricity and deformation of the upper exhaust pipe ensures that the gap between the combustion chamber and the exhaust pipe is within a controllable range, effectively reducing the construction difficulty during combustion chamber hoisting. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the installation of the upper exhaust pipe and the sectional assembly;

[0036] Figure 2 This is a schematic diagram of the installation of the lower exhaust pipe and the main assembly of the sub-sections;

[0037] Figure 3 This is a detailed drawing of the combustion chamber bottom support installation and top screws;

[0038] Figure 4 yes Figure 3 A schematic diagram of the enlarged structure of the middle circle;

[0039] Figure 5 This is a schematic diagram of the set screw device;

[0040] Figure 6 This is a schematic diagram of the top support structure;

[0041] Among them, 1-upper section exhaust pipe, 2-lower section exhaust pipe, 3-sleeve, 4-eye plate, 5-combustion chamber, 6-fan, 7-box body, 8-top screw, 9-GCU combustion chamber support leg, 10-GCU combustion chamber support leg base plate, 11-welded bracket. Detailed Implementation

[0042] The invention will be further described with reference to the accompanying drawings.

[0043] To meet the company's internal transportation capacity requirements, the 16.4m long exhaust pipe needs to be transported in two sections. According to the assembly sequence, the exhaust pipe needs to be prefabricated as a 6.4m upper section and a 10m lower section. Figure 1 , 2 As shown.

[0044] The upper exhaust pipe is pre-installed with exhaust pipe brackets, sensor cable trays and other system accessories. Multiple cross bracing structures need to be added inside to control the cylindricity within -10mm to +10mm to meet the requirements for hoisting and installation of the combustion chamber. A 200mm long sleeve is connected to the bottom of the upper exhaust pipe by nail welding for connecting the upper and lower exhaust pipes.

[0045] The lower exhaust pipe is pre-installed with exhaust pipe supports, pressure detection pipelines and through-chamber components, maintenance manhole covers and various sensor bases. A cross brace is added at the upper interface of the pipe section to ensure that the cylindricity at the welded joint is within -5.5mm to +11mm, meeting the clearance requirements of the combustion chamber top support. After the lower exhaust pipe is manufactured, a front mark is made on the surface of the lower exhaust pipe according to the position of the sensor base for positioning during pre-assembly.

[0046] The upper exhaust pipe, the adjacent chimney section of the upper exhaust pipe, the lower exhaust pipe, and the adjacent section of the lower exhaust pipe together form the upper section of the stern tower.

[0047] 1. After the lower section of the stern tower is assembled and in place, the lower exhaust pipe is hoisted.

[0048] 2. Remove the internal cross support structure of the lower exhaust pipe, locate the lower exhaust pipe, weld it to the installation deck, and temporarily seal it.

[0049] 3. Use roundness inspection fixtures to confirm that the cylindricity of the exhaust pipe meets the requirements for combustion chamber hoisting.

[0050] 4. Use specialized lifting tools to simultaneously secure the four lifting points arranged in a cross shape on the top of the GCU combustion chamber.

[0051] 5. Hoist the GCU combustor from the top of the exhaust pipe. The vertical hoisting distance is about 10m. During the hoisting process, when the GCU combustor is 2 meters away from the bottom deck, use the GCU combustor hoisting eye plate and the hand chain hoist as traction to assist in the placement of the GCU combustor.

[0052] 6. After the GCU combustion chamber is in place, if Figure 3 , 4As shown, the position is adjusted using the top screw 8 device on the deck surface, and the GCU combustor is temporarily fixed to the mounting deck on top of the housing 7; the lifting gear is detached, and the top clearance of the GCU combustor is adjusted using the top screw device on the mounting deck, and four sets of top supports (such as...) are installed on the top of the GCU combustor. Figure 6 As shown, four sets of top supports are evenly spaced along the circumference of the GCU combustion chamber. Each set contains two symmetrically arranged top supports with a gap between them. The centers of the two top supports form a 30° angle with the line connecting the circles of the GCU combustion chamber. The base plate of the top support is fixedly connected to the top plate of the GCU combustion chamber, and the welded bracket 11 of the top support is welded and fixedly connected to the inner wall of the lower exhaust pipe.

[0053] The bottom of the GCU combustion chamber support leg 9 is equipped with a GCU combustion chamber support leg base plate 10. The GCU combustion chamber support leg base plate is welded to the mounting plate via a welding backing plate. Bolts and set screws are arranged side by side, passing through the GCU combustion chamber support leg base plate and the welding backing plate in sequence. The set screw is located between the two bolts. Figure 5 As shown.

[0054] 7. Disconnect the lifting gear, adjust the combustion chamber top clearance by using the top screws on the installation deck, and install the top support.

[0055] 8. After aligning the upper and lower exhaust pipes, adjust the flange pre-installed on the lower exhaust pipe, cover both exhaust pipe sections, and then weld to complete the installation of the exhaust pipes.

Claims

1. A method for hoisting and assembling a gas combustion unit (GCU) for a large LNG carrier, characterized in that, The main body of the GCU exhaust pipe adopts a two-section design, namely an upper exhaust pipe and a lower exhaust pipe, which are connected by a sleeve. The sleeve is pre-installed at the bottom of the upper exhaust pipe. Both ends of the upper and lower exhaust pipes are welded with eye plates, with two eye plates at each end, and the two eye plates are symmetrically arranged. The upper exhaust pipe consists of an upper exhaust section and an adjacent lower exhaust section, and the upper exhaust pipe is equipped with reinforcing supports inside. The lower exhaust pipe is designed independently, and a reinforced support is installed in advance at the connection point at the top of the lower exhaust pipe; Before the upper section of the flue pipe is pre-assembled with the adjacent chimney in sections, the flue pipe support and sensor cable bracket are installed on the upper section of the flue pipe. Before the lower exhaust pipe is pre-assembled with the adjacent section, the exhaust pipe support, pressure detection pipeline, through-cabin parts, maintenance manhole cover and various sensor bases are installed on the lower exhaust pipe. The cylindricity of the upper exhaust pipe is -10mm to +10mm, and the cylindricity of the welded joint at the top of the lower exhaust pipe is -5.5mm to +11mm. The lower section of the sterncastle is located below the installation deck and includes the GCU fan and housing. The housing is a hull structure, and the top of the housing is a ventilation opening. The ventilation opening is located on the installation deck. After the lower section of the sterncastle is installed in place, a hand-operated hoist and a top screw device are pre-installed on the installation deck surface. The specific steps for joining the parts are as follows: S1: Under the ship, connect the upper exhaust section with the lower exhaust section to form the upper exhaust pipe; S2: After the lower section of the sterncastle is installed in place, the lower section of the exhaust pipe is hoisted onto the ship, installed with the lower section of the exhaust pipe and sealed. S3: The upper exhaust pipe is hoisted onto the ship and connected to the lower exhaust pipe through a sleeve. After the connection, temporary reinforcing structures are welded at the eye plate at the bottom of the upper exhaust pipe and at the eye plate at the top of the lower exhaust pipe. S4: Transport the GCU combustion chamber from the top of the upper exhaust pipe downwards. The vertical lifting distance is about 10m. During the lifting process, when the GCU combustion chamber is 2 meters away from the bottom deck, use the GCU combustion chamber lifting eye plate and the hand chain hoist as traction to assist the GCU combustion chamber in its position. After the GCU combustor is in place, its position is adjusted using the deck-mounted screw device to temporarily fix it to the installation deck. The lifting gear is then detached, and the top clearance of the GCU combustor is adjusted using the screw device on the installation deck. Four sets of top supports are then installed on the top of the GCU combustor. The four sets of top supports are evenly spaced along the circumference of the GCU combustor. Each set contains two symmetrically arranged top supports with a gap between them. The center of the two top supports forms a 30° angle with the line connecting the circles of the GCU combustor. S5: After all sections are closed, remove the temporary reinforcing structure and the reinforcing supports inside the upper and lower exhaust pipes.

2. The method for hoisting and assembling a gas combustion unit (GCU) for a large LNG carrier according to claim 1, characterized in that, The sleeve length is 200mm.

3. The method for hoisting and assembling a gas combustion unit (GCU) for a large LNG carrier according to claim 1, characterized in that, The upper exhaust pipe is 6.4 meters long, and the lower exhaust pipe is 10 meters long.

4. The method for hoisting and assembling a gas combustion unit (GCU) for a large LNG carrier according to claim 1, characterized in that, The eyeplate is welded to the reinforcing structure of the insulating frame.

5. The method for hoisting and assembling a gas combustion unit (GCU) for a large LNG carrier according to claim 1, characterized in that, The upper section of the exhaust pipe uses a thickened insulating frame.

6. The method for hoisting and assembling a gas combustion unit (GCU) for a large LNG carrier according to claim 1, characterized in that, The vertical lifting distance of the combustion chamber is 16.6m.

7. The method for hoisting and assembling a gas combustion unit (GCU) for a large LNG carrier according to claim 1, characterized in that, At a height of 2 meters from the bottom deck, the combustion chamber is lowered into position using a hoist and a hand chain hoist.

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