Arrangement method of drainage port of open container ship

Abstract

The invention discloses a method for arranging a drainage port of an open container ship. The method comprises the steps that the drainage port of the open container ship is arranged between a full-load waterline and a final balance waterline; and a valve group with a cut-off and non-return function is arranged at the drainage port. The water immersion amount of the cargo hold can be reduced, and better complete water immersion stability can be obtained; and the difficulty and cost of ship design and construction can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of ships, and in particular to a method for arranging a drainage port of an open container ship. Background Art

[0002] An open top container ship (also known as a "hatchless container ship") is a specially designed container ship with one or more cargo holds without hatch covers. This type of ship has the advantages of high loading and unloading efficiency, flexible loading, and improved ship stability. It has great economic advantages for routes that require frequent port calls for loading and unloading of containers. Open top container ships usually do not have drainage ports, or in order to reduce the amount of water in the hold, drainage ports are set and arranged above the final balanced waterline.

[0003] Since some or all of the cargo holds of open container ships are not equipped with hatch covers for closing the cargo holds, if severe sea conditions occur during navigation, causing a large amount of rainwater and / or waves on the deck to enter the open cargo holds, once the drainage system fails, a large amount of water will accumulate in the cargo holds, which will seriously threaten the safety of the ship. For this reason, the International Maritime Organization (IMO) issued a circular in 1994, which put forward clear requirements for the freeboard height, hull strength, stability and bilge drainage system of open container ships. The circular mentioned that when the ship is fully loaded, it is assumed that the open cargo hold is flooded to the edge of the hatch or the top of the hatch coaming (if the cargo hold is equipped with a drainage port, it is assumed that the flooding reaches the lower edge of its opening), and the complete flooding stability requirements must be met.

[0004] The cargo hold drainage port is an opening located on both sides of the hull above the full load waterline in the cargo hold area, which runs through the inside and outside of the cargo hold / hull and is equipped with a valve group with a stop check function. In any case, the water in the hold can overflow overboard through the valve group, but the seawater outside the hold cannot enter the hold. Therefore, when the drainage port is set, the equilibrium water level in the hold can be effectively reduced.

[0005] When examining the requirements for stability under complete flooding, the higher the equilibrium water level in the hold, the more the draft of the ship increases under flooding, which will lead to a reduction in the ship's reserve buoyancy, which is detrimental to stability. Therefore, in order to reduce the amount of flooding in the hold and obtain better stability under complete flooding, drainage ports are often set up in open cargo holds and arranged above the final equilibrium waterline after the cargo hold is flooded.

[0006] The prior art is divided into two methods: one is not provided with a drainage port, and the other is provided with a drainage port.

[0007] The first method is that when an open container ship is not equipped with drainage ports, the cabin will be flooded to the top of the hatch coaming, the draft will increase significantly, and the ship's reserve buoyancy will be small. Figure 1 As shown, the balance water level 41 in the cargo hold is flush with the top of the hatch coaming, and the final balance waterline 42 is located below the balance water level 41 in the cargo hold.

[0008] The disadvantages of the first method of "not providing drainage ports" are as follows:

[0009] 1. The open cargo hold is flooded to the top of the hatch coaming, the draft increases significantly, the reserve buoyancy of the ship is greatly reduced, and the stability of the ship is poor when fully flooded.

[0010] 2. From the perspective of meeting the necessary complete flooding stability, a larger draft and / or hatch coaming height is required, which will inevitably increase the amount of steel used and the empty ship weight, which will not only increase the construction cost, but also reduce the container volume during operation and reduce profitability.

[0011] The second method is that when an open container ship is equipped with a drainage port, Figure 2 As shown, the equilibrium water level 31 in the cargo hold is at a position "h" meters above the discharge port 30 (h is the head pressure height of the valve group 33 when the valve group is opened, and h is determined according to the product parameters of the valve group), which is obviously lower than the top of the hatch coaming. The draft increases and the reserve buoyancy of the ship is large, and the stability under full flooding is better than the former.

[0012] The disadvantages of the conventional "setting of drainage ports" of the second method are as follows:

[0013] 1. Because the drainage port is arranged above the final equilibrium waterline, the height position is limited, which brings difficulties to the design.

[0014] like Figure 2 and Figure 3 As shown in the figure, due to the increase in draft after flooding, the drainage port can only be arranged on the hatch coaming above the waterline. Since the drainage port needs to ensure that the water in the tank does not accumulate beyond the specified height, it must have a large enough pipe diameter, and the overall size of its combined valve body is large. Its arrangement position will occupy a certain passage space. If the side tank is not wide enough, the side passage width "L" will be less than the legal requirement of 600mm, and other passage solutions need to be found.

[0015] 2. The balance water level in the cabin has not been reduced to the minimum, and there is room for further optimization.

[0016] like Figure 2 As shown in the figure, the installation position of the drainage port 30 is "H" meters higher than the final balance waterline 32 (H is the height between the final balance waterline 32 and the drainage port 30), and the balance water level 31 in the cargo hold is "H+h" meters higher than the final balance waterline 32 (wherein h is the head pressure height of the opening valve group 33, and H is the height between the final balance waterline 32 and the drainage port 30). The larger "H" is, the more water is flooded in the hold, the greater the draft of the ship is, the less the reserve buoyancy is, and it is not good for stability. Summary of the invention

[0017] The technical problem to be solved by the present invention is to overcome the above-mentioned defects in the prior art and to provide a method for arranging the drainage port of an open container ship.

[0018] The present invention solves the above technical problems through the following technical solutions:

[0019] A method for arranging a drainage port of an open container ship, comprising:

[0020] The freeing port of an open container ship is set between the fully loaded waterline and the final balanced waterline;

[0021] A valve group with stop and check function is installed at the discharge port.

[0022] Furthermore, the valve group is composed of a butterfly valve and a butterfly check valve.

[0023] Furthermore, when the drainage port is arranged below the freeboard deck, the valve stem of the butterfly valve is extended above the freeboard deck.

[0024] Furthermore, the drainage port is provided with a drainage pipe, which connects the cargo hold and the outside of the ship.

[0025] Furthermore, the valve group is arranged on the drain pipe.

[0026] Further, the drainage pipes are distributed horizontally.

[0027] The beneficial effects of the present invention are as follows: the method of the present invention can arrange the drainage port below the final balanced waterline without any other special arrangement requirements, and the installation position is flexible; the balanced water level in the cabin can be reduced to the minimum, the flooding amount of the cargo hold is reduced, and better complete flooding stability can be obtained. The method of the present invention can reduce the difficulty and cost of ship design and construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the prior art when no drainage port is provided.

[0029] Figure 2 It is a schematic diagram of setting a drainage port in the prior art.

[0030] Figure 3 The present invention is a schematic diagram of a drainage port when a drainage port is provided in the prior art.

[0031] Figure 4 This is a schematic diagram of the location of the drainage port in a preferred embodiment of the present invention.

[0032] Figure 5 Schematic diagram of the position of the equilibrium water level in the cargo hold of a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0033] A preferred embodiment is given below, and the present invention is described more clearly and completely in conjunction with the accompanying drawings.

[0034] like Figure 4 and Figure 5 As shown, a method for arranging a drainage port of an open container ship comprises:

[0035] The drainage port 10 of the open container ship is arranged between the full load waterline 21 and the final balance waterline 20; and a valve group with a stop check function is arranged at the drainage port 10.

[0036] The valve group consists of a butterfly valve 11 and a butterfly check valve 16.

[0037] For different open container ships, the final equilibrium waterline may be above the freeboard deck or below the freeboard deck.

[0038] When the final equilibrium waterline is above the freeboard deck, the freeing port may be arranged below the freeboard deck or above the freeboard deck.

[0039] When the final equilibrium waterline is below the freeboard deck, the freeing port is arranged below the freeboard deck.

[0040] Therefore, there are two situations for the location of the freeing port: in the first situation, the freeing port is arranged above the freeboard deck; in the second situation, the freeing port is arranged below the freeboard deck.

[0041] For the first case, when the discharge port is arranged above the freeboard deck, the valve stem of the butterfly valve is located above the freeboard deck, and the staff can operate the butterfly valve on the freeboard deck, meeting the requirements of the specification.

[0042] For the second case, when the discharge port 10 is arranged below the freeboard deck 13, the valve stem 12 of the butterfly valve 11 is extended above the freeboard deck 13. The staff can operate the butterfly valve on the freeboard deck, meeting the requirements of the specification.

[0043] The drainage port 10 is provided with a drainage pipe 14, which is connected to the cargo hold 15 and the outside of the ship. The drainage pipe 14 is horizontally distributed. A valve group consisting of a butterfly valve 11 and a butterfly check valve 16 is arranged on the drainage pipe 14.

[0044] The principle of the arrangement method of the present invention is described as follows:

[0045] 1. If the open cargo hold begins to flood, the water level in the cargo hold will gradually increase, causing the ship's draft to increase, but the speed of the water level increase in the cargo hold is faster than the speed of the ship's draft increase. The drainage port will gradually be submerged in water and subjected to the head pressure on both sides. The valve group will remain closed until the head pressure in the cargo hold is higher than the head pressure of the seawater outside the ship and is less than the opening value of the valve group.

[0046] 2. As the water level in the hold continues to increase, when the pressure difference between the inside and outside of the ship reaches its opening value, the valve group opens and the water in the hold can overflow to the outside of the ship, while the water outside the ship will not enter the cargo hold.

[0047] At this time, if Figure 5 As shown, the height of the equilibrium water level 22 in the cargo hold is the height of the final equilibrium waterline 20 plus h, where h is the head pressure height of the open valve group; the height of the equilibrium water level in the cargo hold is no longer related to the specific installation height of the discharge port.

[0048] According to the existing conventional drainage port layout method, such as Figure 2 and Figure 3 As shown, the equilibrium water level 31 in the cargo hold is "H+h" higher than the final equilibrium waterline 32, wherein h is the head pressure height of the open valve group 33; and H is the height between the final equilibrium waterline 32 and the discharge port 30.

[0049] It can be seen that compared with the prior art, the equilibrium water level in the cargo hold of the present invention is "H" meters lower, the amount of water in the hold is less, and the complete flooding stability is better than the existing conventional arrangement method.

[0050] According to the method of the present invention, since the equilibrium water level in the cargo hold is no longer related to the specific position of the drainage port, the drainage port can be flexibly arranged according to needs; the drainage port can be placed after the arrangement requirements of pipelines, cables, personnel passages, etc. in the empty compartment on the side are met, which greatly reduces the difficulty and cost of design and construction.

[0051] The method of the present invention has the following advantages:

[0052] 1. The drainage port can be arranged below the final balanced waterline. There is no other special arrangement requirement and the installation position is flexible.

[0053] 2. The balance water level in the hold can be reduced to the minimum, the amount of water flooding in the cargo hold is reduced, and better complete flooding stability can be obtained.

[0054] 3. Reduce the difficulty and cost of ship design and construction.

[0055] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that this is only for illustration and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A method for arranging a drainage port of an open container ship, characterized in that: It includes: The freeing port of an open container ship is set between the fully loaded waterline and the final balanced waterline; A valve group with stop and check function is installed at the discharge port.

2. The method for arranging the drainage port of an open container ship according to claim 1, characterized in that: The valve group consists of a butterfly valve and a butterfly check valve.

3. The method for arranging the drainage port of an open container ship according to claim 2, characterized in that: When the discharge port is arranged below the freeboard deck, the stem of the butterfly valve is extended above the freeboard deck.

4. The method for arranging the drainage port of an open container ship according to claim 1, characterized in that: The drainage port is provided with a drainage pipe which connects the cargo hold and the outside of the ship.

5. The method for arranging the drainage port of an open container ship according to claim 4, characterized in that: The valve group is arranged on the drain pipe.

6. The method for arranging the drainage port of an open container ship according to claim 4, characterized in that: The drainage pipes are distributed horizontally.

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