Method for expanding capacity of A-type cabin in liquefied gas ship

Abstract

According to the method for expanding the capacity of the A-type cabin in the liquefied gas ship, the A-type cabin is fixed in the ship body, top side cabins are arranged on the two broadsides of the top of the A-type cabin, a deck above the A-type cabin is a three-section type deck, the three-section type deck sequentially comprises a straight section, a large inclined section and a small inclined section from the central axis of the A-type cabin to the broadsides, and the small inclined section serves as a top cabin plate of the top side cabins at the same time. Included angles are formed between the large inclined section and the base line of the ship body and between the small inclined section and the base line, the included angle formed between the small inclined section and the base line is smaller than 5 degrees, and the included angle R2 formed between the large inclined section and the small inclined section is 130 degrees lt; r21t; the included angle R3 formed by the top side cabin inclined plate and the broadside is 45 degrees lt; r < 3lt >; 75 degrees, R < 3 > gt; and R < 2 > is 90 degrees. A deck beam is arranged on the lower surface of the three-section type deck, and the two ends of the deck beam extend to the top side cabin. The multi-section type deck is adopted, cargo loading with larger cabin capacity can be achieved in a channel with limited ship length, ship width and depth, higher economic benefits are achieved, and maximum loading of an existing liquefied gas ship is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of ship gas drag reduction, and in particular relates to a method for expanding the capacity of an A-type tank inside a liquefied gas ship. Background Art

[0002] Green ammonia is considered to be one of the most promising alternative fuels for achieving zero-carbon shipping goals. As a zero-carbon energy source, ammonia fuel can meet more stringent greenhouse gas emission requirements and enable ships to meet the ultimate emission reduction target in 2050. It is estimated that by 2035, the trade volume of clean ammonia will reach 76 million tons, four times the trade volume in 2020. By 2050, the annual trade volume of clean ammonia will exceed 120 million tons. As the demand for clean ammonia is expected to expand, the demand for long-distance liquefied gas transport ships with a stable supply will also continue to increase. At present, liquefied gas ships in the shipping market can also serve as liquefied gas carriers, but only 30% of the world's liquefied gas fleet can transport liquefied gas. Due to restrictions on waterways and ports, only 50 ultra-large liquefied gas carriers have this capability, and the capacity is insufficient.

[0003] For VLGC / VLAC (very large liquefied petroleum gas / liquefied gas carrier), the route with the largest trade volume is the route from the United States to China. Due to the restrictions of the US waterways and ports, the length of the mainstream VLGC / VLAC is limited to within 230m, the width is limited to within 36.6m, and the draft is limited to within 12.2m, resulting in limited depth. For example, the announcement number is: CN108290622B, and the invention name is: Chinese patent for liquefied gas carrier. The hull deck of the existing liquefied gas carrier is a one-stage inclined deck, which is mainly to prevent water accumulation on the deck. The distance between the top of the cargo hold and the centerline of the main deck cannot be less than 1650mm; the bottom is a double-layer structure, and the distance from the outer wall of the A-type tank is H, H≥{2M / 15 or 2m smaller}, M is the half width of the ship, B=2M, B is the full width of the ship, that is, the width of the ship. Therefore, the overall loading weight of the VLGC / VLAC ship type is severely limited. Most VLGC / VLACs use A-type tanks. Given the limited size, how to expand the capacity of the A-tank and increase the loading capacity is a key issue to be solved in this application. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a method for expanding the capacity of the A-type tank inside a liquefied gas ship, aiming to achieve a larger capacity without increasing the length, width and depth of the ship, so that the existing liquefied gas ship type can achieve the purpose of maximum loading. The A-type tank is a diamond-shaped tank, and the tank type can be designed according to the hull line. The A-type tank itself serves as its main shield, and the cargo hold bulkhead hull structure serves as its secondary shield. It is connected to the hull through a special support (pier), so the layout of the hull structure must be considered when considering the size and shape of the liquid tank.

[0005] The technical solution adopted by the present invention is as follows: A method for expanding the hold capacity of Type A holds inside a liquefied gas carrier. A Type A hold is fixed inside the hull. The outer surface shape of the Type A hold is consistent with the inner shape of the hull. Margin tanks are arranged on both sides of the top of the Type A hold. The deck above the Type A hold adopts a three-section deck. From the central axis of the Type A hold to the side, the three-section deck is in sequence a straight section, a large inclination section, and a small inclination section. The small inclination section also serves as the top deck of the margin tank. The straight section is connected to the large inclination section and the small inclination section in sequence to form a complete and continuous three-section deck.

[0006] Both the large inclination section and the small inclination section form an angle with the hull baseline. The angle formed by the small inclination section and the baseline is less than 5 degrees. The large inclination section and the small inclination section form an angle R2, where 130° < R2 < 160°. The angle formed by the inclined plate of the margin tank and the side is R3; 45° < R3 < 75°, R3 > R2 - 90°. The distance between the bulkhead plate of the Type A hold and its nearest hull structure is A, and A > 800 mm.

[0007] Deck beams are arranged on the lower surface of the three-section deck, and both ends of the deck beams extend to the margin tank.

[0008] First, obtain the boundary values F, H, L1, L2, L3, L4, L5, and L6 of the Type A hold.

[0009] Among them, F is the minimum distance between the bulkhead of the Type A hold and the outer hull plate.

[0010] When Vc ≤ 1000 m 3 , F = 0.8 m.

[0011] When 1000 < Vc < 5000 m 3 , F = 0.75 + Vc × 0.2 / 4000 m.

[0012] When 5000 ≤ Vc < 30000 m 3 , F = 0.8 + Vc / 25000 m.

[0013] When Vc ≥ 30000 m 3 , F = 2 m.

[0014] H is the minimum distance between the bottom of the Type A hold and the outer bottom plate of the ship. H is B / 15 or 2 m, taking the minimum value, where B is the ship width.

[0015] L1 is the distance between the bottom of the Type A hold and the inner bottom of the ship, and the value of L1 is 750 mm to 850 mm.

[0016] L2 is the distance between the lower inclined plate of the Type A hold and the lower inclined side of the ship bottom, and the value of L2 is 750 mm to 850 mm.

[0017] L3 is the distance between the upper inclined plate of type A tank and the lower inclined plate of hull, and the L3 value is 750mm~850mm.

[0018] L4 is the distance between the top of the A-type tank and the straight section deck. The value of L4 is C1 / 10 or 1650 mm, whichever is greater; where C1 is the length of the straight section.

[0019] L5 is the height of the inner deck beam of the hull.

[0020] L6 is the vertical distance between the lower inflection point of the upper inclined plate and the intersection of the large inclined section and the small inclined section. L6 is greater than 650 mm.

[0021] The maximum outline of the A-type tank is obtained through the boundary values ​​of the A-type tank, and then the maximum tank capacity of the A-type tank per unit length is obtained. For ports with unrestricted draft, the ship can adopt the design of keeping the molded depth unchanged and increasing the capacity of the A-type tank; for ports with restricted draft, the ship can adopt the design of reducing the ship's molded depth ΔT and increasing the capacity of the A-type tank.

[0022] A: The additional loading weight per unit length in the cabin M A =ΔV×ρ 液 .

[0023] ΔV=sin(R-R3)×cos(R-R3)×N 2 +sin(R)×cos(R)×D1 2 +2×D1×K.

[0024] ΔT=ΔV×ρ 液 / (m×ρ 钢 ).

[0025] Where m is the hull structure area per unit length, ρ 液 is the density of the liquid in the cargo hold, ρ 钢 is the density of steel.

[0026] N is the width of the top inclined plate of the expanded A-type cabin before expansion.

[0027] K is half of the width of the front cabin top plate of the expanded A-type cabin.

[0028] D1 is the height difference between the middle of the expanded A-type cabin before and after expansion when the deck beam is turned inward.

[0029] The maximum loading capacity of type A tank is Vmax=L×B×Td, where L is the length of the ship, B is the width of the ship, T is the depth, and Td is the designed draft. Ship loading capacity = ship structure weight + type A tank loading capacity. When the ship loading capacity is constant, the increase in type A tank capacity requires the reduction of ship structure weight, which is achieved by reducing the ship depth ΔT.

[0030] The above method for expanding the capacity of the A-type tank inside the liquefied gas carrier, further, the straight section length is C1, the straight length at the large inclined section is C2, the straight length at the small inclined section is C3, C2 <C1,C3+C2≈C1。

[0031] The above method for expanding the capacity of the A-type tank inside a liquefied gas carrier, further, the overall width of the three-section deck is 2M, 0.4M≤C1≤0.5M.

[0032] The above method for expanding the capacity of the A-type tank inside the liquefied gas carrier, further, the large inclined section and the straight section form an angle R1, 130° <R1<160°。

[0033] The above method for expanding the capacity of the A-type tank inside a liquefied gas carrier further comprises: the outer surface of the A-type tank is wrapped with an insulating layer, the thickness of the insulating layer is J, and the value range of J is 110mm~130mm.

[0034] The above method for expanding the capacity of the A-type tank inside a liquefied gas carrier further comprises: a top side tank rib is provided in the top side tank, and a plurality of reinforcing ribs are provided on the top side tank rib.

[0035] The above method for expanding the capacity of the A-type tank inside a liquefied gas carrier further comprises: a supporting structure and an anti-roll structure being arranged between the A-type tank and the hull; an anti-roll structure being arranged at the center of the bottom and the top of the A-type tank respectively.

[0036] The above method for expanding the capacity of the A-type tank inside a liquefied gas carrier further comprises providing a gas dome on the top of the A-type tank.

[0037] By changing the hull deck of a liquefied gas ship from a single-stage type to a multi-stage downwardly inclined deck, a larger cargo capacity can be loaded in a waterway where the ship length, ship width and molded depth are limited, which has higher economic benefits, can achieve the maximum loading of existing liquefied gas ship types, improve the loading rate of liquefied petroleum gas / liquefied gas, simplify the construction process, and reduce the empty ship weight. The present invention has huge market prospects and considerable economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic diagram of the structure of a liquefied gas ship according to the present invention; Figure 2 This is a schematic diagram of the maximum outline of the A-type cabin; 1- three-section deck, 2- supporting ribs, 3- supporting structure, 4- top side tank ribs, 5- deck beams, 7- anti-roll structure, 6- A-type tank, 8- side, 9- top side tank sloping plate, 10- air dome. DETAILED DESCRIPTION

[0039] The present invention will be further described in conjunction with the accompanying drawings.

[0040] A method for expanding the internal capacity of type A tank 6 of a liquefied gas carrier. Taking a liquefied gas carrier as an example, the ship length is within 230m, the ship width is 36.6m, and the molded depth is 23.6m. Figure 1 As shown, an A-type tank 6 is arranged inside the liquefied gas hull, and the outer surface shape of the A-type tank 6 is consistent with the inner shape of the hull. The deck above the A-type tank 6 adopts a three-section deck 1, and the three-section deck 1 is symmetrically arranged with the central axis of the A-type tank 6 as the center. The A-type tank 6 is wrapped with an insulating layer on the outside and fixed to the bottom of the ship through a plurality of bottom support structures arranged in a longitudinal column and spaced apart from each other. An anti-roll structure is provided at the center of the bottom and top of the A-type tank 6, and an air dome 10 is also required to be provided on the top of the A-type tank 6.

[0041] The three-section deck 1 is composed of a straight section, a large inclined section, and a small inclined section from the central axis of the A-type tank 6 to the side 8. The small inclined section also serves as the top deck of the top side tank. The straight section is connected with the large inclined section and the small inclined section in sequence to form a complete and continuous three-section deck 1. The length of the straight section is C1, C1=9530mm, the straight length of the large angle inclined section is C2, C2=2990mm, and the straight length of the small angle inclined section is C3, C3=5780mm.

[0042] The large inclined section and the small inclined section both form an angle with the hull baseline, the angle formed by the small inclined section and the baseline is less than 5 degrees, the large inclined section and the straight section form an angle R1=138°, the large inclined section and the small inclined section form an angle R2=141°, and the angle formed by the topside tank sloping plate 9 and the side 8 is R3=54°. Ribs are provided in the topside tank, and a number of reinforcing ribs are provided on the structure of the topside tank rib 4. No large openings are provided, but lightening holes are still provided, and a number of reinforcing ribs are provided on the ribs. A deck beam 5 is provided on the lower surface of the deck, and a supporting rib 2 is provided on the inner surface of the hull side 8. The ends of the deck beam 5 and the supporting rib 2 both stop at the ends of the topside tank sloping plate 9.

[0043] Ship loading capacity = ship structure weight + A-type tank loading capacity.

[0044] In ports where draft is not restricted, the ship can keep the moulded depth unchanged and increase the capacity of type A tank 6, at which time the ship's design draft will increase.

[0045] The present invention does not increase the depth of the model, and the capacity of each meter of A-type cabin is 624m 2 , the deck is raised and the capacity of type A cabin 6 is expanded.

[0046] like Figure 2 As shown in the figure, in ports with no draft restrictions, the ship can keep the molded depth unchanged and increase the capacity of type A tank 6, then the ship's design draft will increase. This is equivalent to replacing the tank capacity with the structural weight, increasing the ship's cargo capacity.

[0047] At this time, the load weight per unit length in cabin A can be increased by M A =ΔV×ρ 液 , ρ 液 is the density of the liquid in the cargo hold.

[0048] Since the ship's loading capacity is fixed, the increased weight of cabin A needs to be achieved by reducing the structural weight. Therefore, the draft can be appropriately reduced, and the reduced draft height is ΔT.

[0049] Before and after the A cabin renovation, the increased cabin capacity ΔV per meter of A cabin 6 is: ΔV=sin(R-R3)×cos(R-R3)×N 2 +sin(R)×cos(R)×D1 2 +2×D1×K=50m 3 .

[0050] N is the width of the front cabin top inclined plate of the expanded A-type cabin 6, N=8490mm.

[0051] K is half of the width of the front cabin top plate of the expanded A-type cabin 6, K=8740mm.

[0052] D1 is the height difference between the middle of the expanded A-type cabin 6 before and after expansion when the deck beam 5 is turned inward, D1=2000mm.

[0053] ΔT=ΔV×ρ 液 / (m×ρ 钢 ).

[0054] Where m is the hull structure area per unit length, ρ 钢 is the density of steel, usually 7.85t / m 3 .

[0055] Assume that the cargo is liquid ammonia with a density of 0.618 t / m 3 ,m=6.5m 2 .

[0056] ΔT=50×0.618 / (7.85×6.5)=0.6m.

[0057] Therefore, the ship can reduce the depth by 0.6m, and then change the structural weight by reducing the depth while ensuring that the ship's loading capacity remains unchanged, thereby increasing the capacity of type A tank 6.

[0058] The present invention provides a design scheme for expanding the capacity of type A tank 6 of a multi-section deck liquefied gas transport ship. By changing the hull deck of the liquefied gas ship from a single section to a multi-section inclined downward deck, a larger cargo capacity can be loaded in a waterway with limited length, width and depth, which has higher economic benefits, can achieve the maximum loading of existing liquefied gas ship types, improve the loading rate of liquefied gas, simplify the construction process, and reduce the empty ship weight. The present invention has huge market prospects and considerable economic benefits.

Claims

1. A method for expanding the capacity of a type A tank inside a liquefied gas carrier, characterized in that: An A-type cabin (6) is fixed inside the hull. The shape of the outer surface of the A-type cabin (6) is consistent with the shape inside the hull. Side tanks are provided on both sides (8) at the top of the A-type cabin (6). The deck above the A-type cabin (6) adopts a three-section deck (1). The three-section deck (1) is, from the central axis of the A-type cabin (6) to the side (8), a straight section, a large inclination section, and a small inclination section in sequence. The small inclination section also serves as the top deck of the side tank. The straight section is connected to the large inclination section and the small inclination section in sequence to form a complete and continuous three-section deck (1); Both the large inclination section and the small inclination section form an angle with the hull baseline. The angle formed by the small inclination section and the baseline is less than 5 degrees. The large inclination section and the small inclination section form an angle R2, where 130° < R2 < 160°. The angle R3 formed by the inclined plate (9) of the side tank and the side (8) is such that 45° < R3 < 75° and R3 > R2 - 90°. The distance between the bulkhead plate of the A-type cabin (6) and its nearest hull structure is A, and A > 800 mm; Deck beams (5) are provided on the lower surface of the three-section deck (1), and both ends of the deck beams (5) extend to the side tank; First, obtain the boundary values F, H, L1, L2, L3, L4, L5, L6 of the A-type cabin (6): Among them, F is the minimum distance between the bulkhead of the A-type cabin (6) and the outer hull plate; When Vc≤1000m 3 , F=0.8m; When 1000 <Vc<5000m 3 , F=0.75+Vc×0.2 / 4000 m; When 5000≤Vc<30000m 3 , F=0.8+Vc / 25000 m; When Vc≥30000m 3 , F = 2 m; H is the minimum distance between the bottom of the A-type cabin (6) and the outer bottom plate of the ship. H is the minimum of B / 15 or 2 m, where B is the ship width; L1 is the distance from the bottom of the A-type cabin (6) to the inner bottom, and the value of L1 is 750 mm to 850 mm; L2 is the distance from the lower inclined plate of the A-type cabin (6) to the lower inclined edge of the ship bottom, and the value of L2 is 750 mm to 850 mm; L3 is the distance from the upper inclined plate of the A-type cabin (6) to the lower inclined plate of the hull, and the value of L3 is 750 mm to 850 mm; L4 is the distance from the top of the A-type cabin (6) to the straight section deck. The value of L4 is the maximum of C1 / 10 or 1650 mm. Among them, C1 is the length of the straight section; L5 is the height of the inner deck beam in the ship; L6 is the vertical distance from the lower folding point of the upper inclined plate to the intersection point of the large inclination section and the small inclination section, and L6 is greater than 650 mm; Through the boundary values of the A-type cabin (6), obtain the maximum contour of the A-type cabin (6), and then obtain the maximum cabin volume per unit length of the A-type cabin (6). For ports where the draft is not restricted, the ship can adopt a design of keeping the depth constant and increasing the cabin volume of the A-type cabin (6); for ports where the draft is restricted, the ship can adopt a design of reducing the ship depth ∆T and increasing the cabin volume of the A-type cabin (6); A: The additional loading weight per unit length in the cabin M A =∆V×ρ 液 ; ΔV=sin(R-R3)×cos(R-R3)×N 2 +sin(R)×cos(R)×D1 2 +2×D1×K=50m 3 ; ΔT=ΔV×ρ 液 / ( m×ρ 钢 ); Where m is the hull structure area per unit length, ρ 液 is the density of the liquid in the cargo hold, ρ 钢 is the density of steel; N is the width of the top inclined plate of the A-type cabin (6) before capacity expansion; K is half of the width of the top deck of the A-type cabin (6) before capacity expansion; D1 is the height difference in the middle of the A-type cabin (6) before and after capacity expansion when the deck beam (5) is turned inward.

2. A method for expanding the capacity of type A tanks inside a liquefied gas carrier according to claim 1, characterized in that: The straight length at the large inclination section is C2, and the straight length at the small inclination section is C3. C2 < C1, and C3 + C2 ≈ C1.

3. A method for expanding the capacity of type A tanks inside a liquefied gas carrier according to claim 1, characterized in that: The overall width of the three-section deck (1) is 2M, and 0.4M ≤ C1 ≤ 0.5M.

4. A method for expanding the capacity of type A tanks inside a liquefied gas carrier according to claim 1, characterized in that: The large inclination section and the straight section form an angle R1, where 130° < R1 < 160°.

5. A method for expanding the capacity of type A tanks inside a liquefied gas carrier according to claim 1, characterized in that: The outer surface of the A-type cabin (6) is wrapped with an insulating layer, the thickness of the insulating layer is J, and the value range of J is 110mm~130mm.

6. A method for expanding the capacity of type A tanks inside a liquefied gas carrier according to claim 1, characterized in that: A top side tank rib (4) is arranged in the top side tank.

7. A method for expanding the capacity of type A tanks inside a liquefied gas carrier according to claim 1, characterized in that: A supporting structure (3) and an anti-roll structure (7) are arranged between the A-type cabin (6) and the hull, and an anti-roll structure (7) is arranged at the center of the bottom and top of the A-type cabin (6).

8. A method for expanding the capacity of type A tanks inside a liquefied gas carrier according to claim 1, characterized in that: An air dome (10) is provided on the top of the A-type cabin (6).

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