A high-efficiency oil boom suitable for oil spill containment in ice-breaking areas

Abstract

This invention discloses a high-efficiency oil boom suitable for oil spill containment in areas with ice floes. The boom is equipped with foam float bags filled with foam particles to generate buoyancy. This foam float bag provides continuous buoyancy even when the float bags are scratched by ice floes, ensuring the boom's continued operation. Two counterweight chains are installed on the boom, located above and below the ice-proof net and oil-proof sheet, respectively. These chains tighten the ice-proof net and provide sufficient tensile force to allow the net to unfold and tighten in seawater containing ice floes, effectively protecting the oil-proof sheet from scratches and completely sealing off the oil spill area. This effectively solves the problem of oil spill containment in areas with ice floes and improves the emergency response capability for such spills.

Description

Technical Field

[0001] This patent belongs to the fields of marine environmental pollution and environmental protection equipment, and in particular relates to a high-efficiency oil containment boom suitable for oil spill containment in ice-breaking areas. Background Technology

[0002] The destruction of the marine ecological environment can lead to environmental pollution and damage in coastal areas, and may also threaten human health and life. Marine oil spills can have a devastating impact on the marine ecological environment, causing many plants and animals to be on the verge of extinction. In addition, industries such as fisheries and tourism cannot function without the health of the marine ecological environment. Marine oil spills damage the ecological environment, causing not only immediate losses, but also long-term negative impacts on the local economy.

[0003] In the national strategy, it is necessary to utilize and develop the Arctic shipping route. In the process of developing the Arctic shipping route, more consideration needs to be given to the harmonious coordination with the marine environment. Correspondingly, it is necessary to have the ability to deal with accidental oil spills in the Arctic shipping route in a timely manner.

[0004] The environment along the Arctic shipping route is completely different from that in my country's territorial waters. my country's territorial waters are ice-free, and its related technologies and equipment have gradually improved, giving it a certain capacity for oil spill emergency response. However, these technologies cannot be applied to ice-covered conditions such as the Arctic shipping route. Oil booms are a crucial technology for preventing oil spills from spreading, but traditional oil booms cannot be used in areas with broken ice, presenting numerous problems. First, a large amount of ice floes in the ice-covered area float up and down within a few meters below the sea surface, and their specific positions are not stable. When traditional oil booms are deployed directly, the counterweight of the booms is too low, and the booms are very likely to fall onto the ice floes and be supported by them, preventing them from reaching an upright working state, resulting in oil leaks in the enclosed area. The ice floes move randomly in the seawater, and they are very likely to puncture the air bladders or oil-proof cloth of the oil booms. Punctures to the air bladders cause a significant loss of buoyancy to the booms, which may cause them to sink directly to the bottom. Punctures to the oil-proof cloth will also cause oil leaks in the enclosed area, affecting the final disposal effect. In addition, the oil spill can be absorbed on the sea ice, or it can exist in ice cracks and on the ice bottom. The oil spill can spread through sea ice cracks or the bottom, bypassing the existing oil booms.

[0005] For the reasons mentioned above, the inventors conducted in-depth research on existing oil booms in order to design a high-efficiency oil boom suitable for controlling oil spills in ice-breaking areas, which can solve the above problems. Summary of the Invention

[0006] To overcome the aforementioned problems, the inventors conducted in-depth research and designed a highly efficient oil boom suitable for oil spill containment in ice-covered areas. This oil boom is equipped with foam float bags, which generate buoyancy by filling with foam particles. This foam float bag can continuously provide buoyancy even if it is scratched by ice fragments, ensuring the oil boom continues to operate. The oil boom also features two counterweight chains, located above and below the ice-proof net and oil-proof sheet, respectively. These chains tighten the ice-proof net and provide sufficient tensile force, allowing the net to unfold and tighten in seawater containing ice fragments, effectively protecting the oil-proof sheet and preventing it from being scratched by the ice. The oil-proof sheet then completely seals off the oil spill area. This effectively solves the problem of oil spill containment in ice-covered areas and improves the emergency response capability for oil spills in such areas, thus completing this invention.

[0007] Specifically, the purpose of this invention is to provide a high-efficiency oil boom suitable for oil spill containment in ice-breaking areas. This high-efficiency oil boom includes a connecting end A 1 on one side and a connecting end B 2 on the other side.

[0008] Between connection A1 and connection B2, from top to bottom, there are foam float bags 3, upper counterweight chains 4, oil-proof cloth 5, anti-icing nets 9 and lower counterweight chains 6.

[0009] The foam float bag 3 can be filled with foam particles;

[0010] The oil-proof cloth 5 and the anti-icing net 9 are arranged in parallel.

[0011] In the vertical direction, the size of the oil-proof cloth 5 is larger than the size of the anti-icing net 9;

[0012] Both the upper counterweight chain 4 and the lower counterweight chain 6 are metal chains. By tightening the anti-icing net 9 through the upper counterweight chain 4 and the lower counterweight chain 6, the anti-icing net 9 can be unfolded, tightened and kept upright when laying high-efficiency oil booms in the ice-breaking area.

[0013] The foam float bag 3 is connected to a foam filling pipe 7. When laying the high-efficiency oil boom, foam particles are filled into the foam float bag 3 through the foam filling pipe 7.

[0014] Both the connecting end A 1 and the connecting end B 2 are straight rods.

[0015] A through slot 11 is provided along the length of the connection end A 1.

[0016] A lateral protrusion 21 is provided along the length direction of the connection end B2.

[0017] The protruding ridge 21 can be inserted into the notch 11 from the top, thereby quickly fixing the connection end A 1 and the connection end B 2 together.

[0018] A bolt hole A12 is provided on end A1.

[0019] A bolt hole B22 is provided on end B2 of the connection.

[0020] When connecting end A1 and end B2 are fixed together, the connection is reinforced and locked by bolts passing through bolt holes A12 and B22.

[0021] The upper counterweight chain 4 is covered and fixed with an upper layer 41, and the lower counterweight chain 6 is covered and fixed with a lower layer 61; both the upper layer 41 and the lower layer 61 include a sealed cloth sleeve.

[0022] An upper connecting skirt 81 is provided above the upper covering layer 41, and the foam float bag 3 is fixed to the upper covering layer 41 by the upper connecting skirt 81;

[0023] A middle connecting skirt 82 is provided below the upper cladding layer 41, and the upper cladding layer 41 is fixed to the oil-proof cloth 5 and the anti-icing net 9 through the middle connecting skirt 82;

[0024] A lower connecting skirt 83 is provided above the lower cladding layer 61, through which the oil-proof cloth 5 and the anti-icing net 9 are fixed to the lower cladding layer 61.

[0025] The cloth cover, upper connecting skirt 81, middle connecting skirt 82 and lower connecting skirt 83 are all made of the same material as the oil-proof cloth 5.

[0026] The anti-icing net 9 is located on the inner side of the oil-proof cloth 5, which is the side facing the inside of the area enclosed by the oil boom. The anti-icing net 9 separates the oil-proof cloth 5 from the broken ice in the area enclosed by the oil boom.

[0027] The ice-proof net 9 is a rope net that can deform appropriately when impacted by broken ice and can return to its initial taut state under the action of the lower counterweight chain 6.

[0028] The size of the foam particles filled into the foam float bag 3 through the foam filling pipe 7 is adjustable, and the size of the foam particles can be adjusted according to the size distribution of ice fragments in the ice crushing zone.

[0029] Among them, there are two types of spherical foams that are filled into the foam float bag 3 through the foam filling pipe 7: one is basic buoyancy foam, which is relatively small in size, and the other is partition foam, which is relatively large in size.

[0030] The beneficial effects of this invention include:

[0031] (1) The high-efficiency oil boom provided by the present invention for oil spill containment in crushed ice areas can effectively solve the problems of difficult deployment of oil booms in crushed ice areas, impact damage and oil spill spreading with ice, effectively solve the problem of oil spill containment in crushed ice areas, and improve the emergency response capability for oil spills in crushed ice areas.

[0032] (2) The high-efficiency oil boom for oil spill containment in ice-breaking areas provided by the present invention improves the service life of the oil boom by filling the float bag with foam. Even when the float bag is scratched and leaked by ice, it can still provide stable buoyancy, so that the oil boom can continue to work.

[0033] (3) According to the present invention, the high-efficiency oil containment boom suitable for oil spill control in ice-breaking areas is provided with two counterweight chains, which can provide sufficient downward gravity for the oil containment boom. In the case of ice-breaking obstruction, the oil containment boom can also be stretched and tightened downward to promote the full unfolding of the oil-proof cloth. It can also tighten the ice-breaking net and the oil-proof cloth in the horizontal direction to ensure the containment effect of oil spill in ice-breaking areas.

[0034] (4) The high-efficiency oil boom provided by the present invention for oil spill containment in ice-breaking areas is provided with two connecting ends that cooperate with each other, which enables multiple oil booms to be quickly connected and assembled to each other, thereby improving the deployment efficiency of the oil booms. Attached Figure Description

[0035] Figure 1 This invention provides a schematic diagram of the overall structure of a high-efficiency oil boom suitable for oil spill containment in ice-breaking areas, according to a preferred embodiment of this application.

[0036] Figure 2 Show Figure 1 A cross-sectional schematic diagram at point 1-1, which is a side view of an efficient oil containment system suitable for oil spill control in ice-breaking areas;

[0037] Figure 3 Show Figure 1 A cross-sectional view at point 2-2, i.e., the cross-sectional view connecting end A;

[0038] Figure 4 Show Figure 1 The cross-sectional diagram at point 3-3 is the cross-sectional diagram connecting end B.

[0039] Explanation of icon numbers:

[0040] 1-Connect to Terminal A

[0041] 11-Gap

[0042] 12- Bolt Hole A

[0043] 2-Connect to B end

[0044] 21-convex ridge

[0045] 22- Bolt Hole B

[0046] 3-Foam float bag

[0047] 4- Upper counterweight chain

[0048] 41-Upper Cladding

[0049] 5-Oilproof cloth

[0050] 6-Lower counterweight chain

[0051] 61-Lower Cladding

[0052] 7-Foam-filled pipes

[0053] 81-Upper connecting skirt

[0054] 82-Middle connecting skirt

[0055] 83-Lower connecting skirt

[0056] 9-Anti-icing netting Detailed Implementation

[0057] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present invention will become clearer and more apparent.

[0058] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0059] According to the present invention, a high-efficiency oil boom suitable for oil spill containment in ice-breaking areas is provided, such as... Figure 1 and Figure 2 As shown, the high-efficiency oil boom includes a connecting end A 1 on one side and a connecting end B 2 on the other side.

[0060] Between connection A1 and connection B2, from top to bottom, there are foam float bags 3, upper counterweight chains 4, oil-proof cloth 5, anti-icing nets 9 and lower counterweight chains 6.

[0061] The foam float bag 3 can be filled with foam particles, which can be of any shape. In this application, they are preferably spherical to improve filling efficiency.

[0062] The oil-proof cloth 5 and the anti-icing net 9 are arranged in parallel; that is, the top ends of the two are fixed together and the bottom ends are also fixed together. In the vertical direction, the size of the oil-proof cloth 5 is larger than the size of the anti-icing net 9, so that when the anti-icing net 9 is stretched, there is a certain space between the oil-proof cloth and the anti-icing net 9, and the oil-proof cloth 5 will not be damaged when the anti-icing net 9 is deformed due to the impact of ice fragments.

[0063] The upper counterweight chain 4 and the lower counterweight chain 6 are both metal chains, such as stainless steel chains. By tightening the anti-icing net 9 through the upper counterweight chain 4 and the lower counterweight chain 6, the anti-icing net 9 can be unfolded and tightened and kept in a vertical state when laying high-efficiency oil booms in the ice-breaking area, thereby driving the oil-proof cloth 5 into a vertical working state.

[0064] In this application, the upper counterweight chain 4 and the lower counterweight chain 6 are set to provide sufficient gravity, enabling the ice-proof net 9 to overcome the obstruction of ice fragments, allowing seawater to enter and maintain an upright state. Simultaneously, the upper and lower counterweight chains tighten the oil-proof cloth horizontally, ensuring that both the oil-proof cloth and the ice-proof net are in an open state. The inventors' research revealed that when counterweight chains are set at both ends of the ice-proof net, it is easiest for the net to enter a vertically open state. Adding counterweight chains to the middle or other parts of the ice-proof net does not further improve its deployment efficiency. Furthermore, the inventors found that on a one-meter-long oil boom, a counterweight chain weighing 23 kg is sufficient to ensure smooth deployment of the ice-proof net even with ice fragments, while also minimizing the weight and volume of the oil boom. With a fixed counterweight chain weight, the diameter of the foam float bags on the oil boom is appropriately matched to ensure sufficient buoyancy, keeping the top of the oil boom floating on the sea surface.

[0065] In addition, the upper counterweight chain of this application is located at a height close to the foam float bag 3. When ice fragments approach the oil boom, they will generally collide with the upper counterweight chain first, and then may further collide with the anti-icing net and the oil-proof cloth. However, after being buffered by the upper counterweight chain, even if they collide with the anti-icing net and the oil-proof cloth, it is difficult to cause damage to them. That is, the upper counterweight chain of this application also has the function of buffering the impact of ice fragments and protecting the anti-icing net and the oil-proof cloth.

[0066] Preferably, the two ends of the counterweight chain extend from the connecting end to further reinforce the two adjacent oil booms, and the extended counterweight chain can also be used to tighten the oil-proof cloth and the anti-icing net to ensure the oil-blocking effect.

[0067] In a preferred embodiment, such as Figure 1 As shown, a foam filling pipe 7 is connected to the foam float bag 3. When laying the high-efficiency oil boom, foam particles are filled into the foam float bag 3 through the foam filling pipe 7.

[0068] In this application, at least one foam filling pipe 7 is provided on each foam float bag 3. The length of an oil boom is preferably set to 10 meters, and 2-4 foam float bags are provided on each oil boom accordingly.

[0069] Preferably, the size of the foam particles filled into the foam float bag 3 through the foam filling pipe 7 is adjustable, allowing the size of the foam particles to be adjusted according to the size distribution of ice fragments in the ice-crushing zone. When the ice fragments in the ice-crushing zone are too large, the size of the foam particles needs to be increased accordingly so that the foam particles inside the foam float bag 3 are less likely to overflow if damaged.

[0070] Preferably, two types of foam particles are filled into the foam float bag 3 through the foam filling pipe 7: one is basic buoyancy foam, which is relatively small in size, and the other is partition foam, which is relatively large in size. Both types of foam particles are set to be spherical. The diameter of the basic buoyancy foam is 1-5 cm, and the diameter of the partition foam is 5-10 cm. That is, the diameters of the basic buoyancy foam and the partition foam are adjusted and selected within the above-mentioned size range according to the size of the ice block. A larger number of basic buoyancy foam particles are set, which mainly provide buoyancy. A smaller number of partition foam particles are set, which are mainly used to separate the basic buoyancy foam in the foam float bag. This ensures that even if the foam float bag is damaged and the gap is large in extreme cases, only a portion of the basic buoyancy foam will overflow, and the oil boom can still maintain its working state.

[0071] Because the foam filling pipe 7 is relatively long, with one end located on the ship and the other end connected to the oil boom, spherical foam needs to be filled in real time during the deployment of the oil boom. The larger the diameter of the spherical foam, the more difficult it is to fill and the lower the filling efficiency. Based on this, the method of filling the basic buoyancy foam and the partition foam alternately in this application can maximize the balance between filling efficiency and the working stability of the oil boom. Preferably, the inventors have found that setting the ratio of basic buoyancy foam to partition foam to 20:1, filling 200 basic buoyancy foams, then filling 10 partition foams, then filling another 200 basic buoyancy foams, and so on until the foam float bag is full, results in foam float bags with the best practicality. The filling efficiency of the spherical foam can meet the deployment speed requirements of the oil boom and also ensure that the obtained oil boom has the expected stability. That is, even when the foam float bag is cut with a large gap and some basic buoyancy foam overflows, it can still continue to work and will not sink.

[0072] Through experimentation, the inventors have discovered that the foam float bags on the oil booms used in this application, filled with 3cm diameter base buoyancy foam and 8cm diameter partition foam in a 20:1 ratio, maintain an effectiveness rate of over 99% after one day of operation in a Class I sea state area with floating ice. Similarly, after one day of operation in a Class IV sea state area with floating ice, the effectiveness rate remains above 95%. "Effective" refers to the foam float bags' ability to maintain the oil boom at its working height, effectively isolating the oil. "Effectiveness" refers to the proportion of effective oil booms among the deployed units. The stronger the waves, the greater the impact of ice fragments on the oil booms; however, the oil booms described in this application still maintain good performance even in Class IV sea states.

[0073] During the test, spherical foam with a diameter of 1 cm was filled into the same foam float bag. After working for one day in a sea state of ice-covered area (Sea State I), the oil boom with such foam float bag had an effectiveness rate of 96%. After working for one day in a sea state of ice-covered area (Sea State IV), the oil boom with such foam float bag had an effectiveness rate of 90%.

[0074] In a preferred embodiment, such as Figure 3 and Figure 4 As shown, both connection end A 1 and connection end B 2 are straight rods.

[0075] A through slot 11 is provided along the length of the connection end A 1.

[0076] A lateral protrusion 21 is provided along the length direction of the connection end B2.

[0077] The protruding ridge 21 can be inserted into the notch 11 from the top, thereby quickly fixing the connection end A 1 and the connection end B 2 together.

[0078] Preferably, to improve connection strength, bolt holes A12 are provided on connection end A1 and B22 are provided on connection end B2. When connection end A1 and connection end B2 are fixed together, they are reinforced and locked by bolts passing through bolt holes A12 and B22. These two mating connection ends enable the rapid connection and assembly of multiple oil booms, improving the deployment efficiency of the oil booms.

[0079] In a preferred embodiment, an upper covering layer 41 is fixedly wrapped around the outside of the upper counterweight chain 4, and a lower covering layer 61 is fixedly wrapped around the outside of the lower counterweight chain 6; preferably, both the upper covering layer 41 and the lower covering layer 61 include a sealed cloth sleeve.

[0080] An upper connecting skirt 81 is provided above the upper covering layer 41, and the foam float bag 3 is fixed to the upper covering layer 41 by the upper connecting skirt 81;

[0081] A middle connecting skirt 82 is provided below the upper cladding layer 41, and the upper cladding layer 41 is fixed to the oil-proof cloth 5 and the anti-icing net 9 through the middle connecting skirt 82;

[0082] A lower connecting skirt 83 is provided above the lower cladding layer 61, through which the oil-proof cloth 5 and the anti-icing net 9 are fixed to the lower cladding layer 61.

[0083] Preferably, the cloth cover, upper connecting skirt 81, middle connecting skirt 82 and lower connecting skirt 83 are all made of the same material as the oilproof cloth 5, and can all play the role of oil-proof cloth in blocking oil, thereby ensuring that there is no leakage in the vertical direction and preventing oil spillage.

[0084] In a preferred embodiment, the anti-icing net 9 is disposed on the inner side of the oil-proof cloth 5, the inner side being the side facing the interior of the area enclosed by the oil boom, and the anti-icing net 9 separates the oil-proof cloth 5 from the broken ice in the area enclosed by the oil boom.

[0085] The ice-proof net 9 is a rope net with sufficiently high connection strength, capable of appropriate deformation when impacted by ice fragments, and able to return to its initial taut state under the action of the lower counterweight chain 6. The inventors have discovered that when the ice-proof net 9 is woven from 7mm diameter polyethylene rope with a rhomboid mesh shape and an area of ​​20 square centimeters, the oil boom has the longest service life, continuously providing containment until the oil spill in the area is completely cleaned up; the containment effect is optimal, with minimal damage to the oil-proof cloth and almost no oil leakage. In other words, ice fragments will not damage the oil-proof cloth, nor will they place excessive burden on the oil boom, preventing its complete destruction.

[0086] Through experiments, the inventors have found that after one day of operation in a sea state of ice-covered Class I area, the oil boom equipped with the anti-icing net described in this application maintains an oil tarpaulin integrity rate of over 99%, and after one day of operation in a sea state of ice-covered Class IV area, the oil boom equipped with the anti-icing net described in this application maintains an oil tarpaulin integrity rate of over 95%. The integrity of the oil tarpaulin refers to the absence of holes in the oil tarpaulin that allow oil to pass through. The effectiveness rate refers to the proportion of intact oil tarpaulins among the multiple deployed oil tarpaulins.

[0087] During the test, an ice-proof net with a diamond-shaped mesh and an area of ​​50 square centimeters was also installed on the oil boom. After working for one day in a sea state of ice-covered area, the integrity rate of the oil boom was 95%. After working for one day in a sea state of ice-covered area, the integrity rate of the oil boom was 85%.

[0088] The present invention has been described above with reference to preferred embodiments; however, these embodiments are merely exemplary and illustrative. Various substitutions and modifications can be made to the present invention based on these embodiments, all of which fall within the scope of protection of the present invention.

Claims

1. A high-efficiency oil boom suitable for oil spill containment in ice-breaking areas, characterized in that, The high-efficiency oil boom includes a connection end A (1) on one side and a connection end B (2) on the other side. Between the connection end A (1) and the connection end B (2), from top to bottom, there are foam float bags (3), upper counterweight chains (4), oil-proof cloth (5), anti-icing net (9) and lower counterweight chains (6). The foam float bag (3) is filled with foam particles; The oil-proof cloth (5) and the anti-icing net (9) are arranged in parallel; In the vertical direction, the size of the oil-proof cloth (5) is larger than the size of the anti-icing net (9); The anti-icing net (9) is set on the inner side of the oil-proof cloth (5), the inner side being the side facing the inside of the area enclosed by the oil boom. The anti-icing net (9) separates the oil-proof cloth (5) from the broken ice in the area enclosed by the oil boom. The ice-proof net (9) is a rope net that can deform appropriately when impacted by broken ice and can return to its initial taut state under the action of the lower counterweight chain (6); The upper counterweight chain (4) and the lower counterweight chain (6) are both metal chains. The anti-icing net (9) is tightened by the upper counterweight chain (4) and the lower counterweight chain (6) so that when laying high-efficiency oil booms in the ice-breaking area, the anti-icing net (9) can be unfolded, tightened and kept upright; the upper counterweight chain (4) is located at a height close to the foam float bag (3). A foam filling pipe (7) is connected to the foam float bag (3). When laying the high-efficiency oil boom, foam particles are filled into the foam float bag (3) through the foam filling pipe (7). The size of the foam particles filled into the foam float bag (3) through the foam filling pipe (7) is adjustable, and the size of the foam particles is adjusted accordingly according to the size distribution of the ice in the ice crushing area. There are two types of spherical foams that are filled into the foam float bag (3) through the foam filling pipe (7). One type is basic buoyancy foam and the other type is partition foam. Both types of foam particles are spherical. The diameter of the basic buoyancy foam is 1-5 cm and the diameter of the partition foam is 5-10 cm. Both the connecting end A (1) and the connecting end B (2) are straight rods. A through slot (11) is provided along the length of the connection end A (1). A convex ridge (21) protruding to the side is provided along the length direction of the connection end B (2). The protruding ridge (21) can be inserted into the slot (11) from the top, thereby quickly fixing the connection end A (1) and the connection end B (2).

2. The high-efficiency oil boom suitable for oil spill containment in ice-breaking areas according to claim 1, characterized in that, A bolt hole A (12) is provided on the connection end A (1). A bolt hole B (22) is provided on the connection end B (2). When the connection end A (1) and the connection end B (2) are fixedly connected, the connection end A (1) and the connection end B (2) are reinforced and locked by bolts passing through bolt holes A (12) and B (22).

3. The high-efficiency oil containment boom suitable for oil spill control in ice-breaking areas according to claim 1, characterized in that, An upper cover (41) is fixed to the outside of the upper counterweight chain (4), and a lower cover (61) is fixed to the outside of the lower counterweight chain (6); both the upper cover (41) and the lower cover (61) include a sealed cloth sleeve. An upper connecting skirt (81) is provided above the upper cladding (41) to fix the foam float bag (3) to the upper cladding (41); A middle connecting skirt (82) is provided below the upper cladding layer (41), and the upper cladding layer (41) is fixed to the oil-proof cloth (5) and the anti-icing net (9) by the middle connecting skirt (82); A lower connecting skirt (83) is provided above the lower cladding layer (61) to fix the oilproof cloth (5), the anti-icing net (9) and the lower cladding layer (61).

4. The high-efficiency oil containment boom suitable for oil spill control in ice-breaking areas according to claim 3, characterized in that, The cover, upper connecting skirt (81), middle connecting skirt (82) and lower connecting skirt (83) are all made of the same material as the oil-proof cloth (5).

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