Ultralow-temperature fluid leakage safety disposal system for offshore steel structure

Abstract

The invention discloses an ultralow-temperature fluid leakage safety disposal system for an offshore steel structure, the ultralow-temperature fluid leakage safety disposal system for the offshore steel structure comprises a wharf central manifold area and a wharf side unloading area, the wharf side unloading area is provided with a low-temperature cofferdam, and the wharf central manifold area is provided with a low-temperature collecting tray; the low-temperature cofferdam and the low-temperature collecting tray are connected with a discharge branch pipe through a low-temperature hose, the discharge branch pipe is connected to a discharge manifold, and leaked liquefied natural gas is discharged to the sea along the discharge manifold; and temperature sensors are arranged on the low-temperature cofferdam and the low-temperature collecting tray, are connected with an automatic sea discharging valve arranged on the discharging manifold, and control opening or closing of the automatic sea discharging valve. According to the safety disposal system for ultralow-temperature fluid leakage of the offshore steel structure, leaked liquefied natural gas is collected in time and discharged to a safety position far away from a platform, and the situation that the steel structure, equipment and pipelines of an offshore wharf are damaged by the low-temperature liquefied natural gas is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of marine oil and gas development, and in particular relates to a safe disposal system for ultra-low temperature fluid leakage of an offshore steel structure. Background Art

[0002] The boiling point of liquefied natural gas under the conditions of terminal transportation is generally below -160℃. Once a leak occurs, the ultra-low temperature liquefied natural gas liquid and supercooled steam in the leaked treatment will cause low temperature damage to people in the nearby area. At the same time, the low temperature causes the cold contraction and toughness reduction of the metal, destroying the stress of the metal. The evaporated natural gas from the liquefied natural gas leak will also cause fire and explosion, as well as the risk of suffocation. Therefore, liquefied natural gas leaks need to be collected and disposed of in a timely manner.

[0003] For emergency disposal of LNG leakage on land, a concrete ground collection area, concrete cofferdam and collection ditch are generally set up. LNG is diverted to the accident collection pool through the collection ditch, and the LNG in the accident collection pool is covered with fire water and foam. The collection ditch and the accident collection pool are located away from the LNG storage and processing equipment to avoid affecting personnel and plant areas.

[0004] Offshore LNG terminals cannot adopt similar practices. First, because offshore terminals are all made of steel structures, and their metal materials are sensitive to low temperatures, LNG will cause deformation, displacement, and brittle fracture of structures, equipment, and pipelines, affecting the safety of the entire terminal. Secondly, offshore terminals are densely populated, and fire, explosion, and low-temperature suffocation have serious consequences for personnel. Thirdly, offshore terminals are compactly arranged and have small spaces, so it is impossible to set up accident collection pools far away from the terminals, high-multiple foam coverings, and other safety measures. At the same time, the space and weight compactness of equipment and pipeline dimensions are required to be high.

[0005] Therefore, there is an urgent need to design a safe disposal system for ultra-low temperature fluid leakage of offshore steel structures to solve the problem of collecting and discharging the leaked liquefied natural gas mentioned above. Summary of the invention

[0006] In order to solve the technical problem that the offshore docks mentioned in the background technology are all steel structures, and their metal materials are sensitive to low temperatures, and liquefied natural gas will cause deformation, displacement and brittle fracture of structures, equipment and pipelines, affecting the safety of the entire dock, a ultra-low temperature fluid leakage safety disposal system for offshore steel structures is provided to solve the problem of collecting and discharging leaked liquefied natural gas.

[0007] To achieve the above-mentioned purpose, the specific technical scheme of the ultra-low temperature fluid leakage safety disposal system of the offshore steel structure of the present invention is as follows: A safe disposal system for ultra-low temperature fluid leakage of offshore steel structures, comprising a central manifold area of ​​a dock and a dock side unloading area, the dock side unloading area is provided with a low temperature cofferdam, and the central manifold area of ​​the dock is provided with a low temperature collecting tray; the low temperature cofferdam and the low temperature collecting tray are both connected to a discharge branch pipe through a low temperature hose, the discharge branch pipe is connected to the discharge manifold, and the leaked liquefied natural gas is discharged into the sea along the discharge manifold; the low temperature cofferdam and the low temperature collecting tray are both provided with temperature sensors, the temperature sensors are connected to an automatic sea discharge valve provided on the discharge manifold, and the temperature sensors control the opening or closing of the automatic sea discharge valve.

[0008] Furthermore, a first wharf side unloading area and a second wharf side unloading area are respectively provided on both sides of the wharf central manifold area, and a first low-temperature cofferdam and a second low-temperature cofferdam are respectively provided in the first wharf side unloading area and the second wharf side unloading area.

[0009] Furthermore, cryogenic hoses are connected to the bottom of the cryogenic collecting plate, the first cryogenic cofferdam and the second cryogenic cofferdam, and the cryogenic hoses are welded to the discharge branch pipe.

[0010] Furthermore, one end of the discharge branch pipe away from the low-temperature hose is connected to the discharge manifold, and an automatic sea discharge valve is provided on the side of the discharge manifold away from the discharge branch pipe.

[0011] Furthermore, three temperature probes are provided in the low-temperature collection tray, the first low-temperature cofferdam and the second low-temperature cofferdam, and the three temperature probes are respectively connected to three temperature sensors so that the temperature sensors control the opening or closing of the automatic sea discharge valve.

[0012] Furthermore, when at least two of the three temperature sensors receive two low temperature alarm signals, the automatic sea discharge valve is controlled to open.

[0013] Furthermore, a welded pipe cap is welded on one end of the discharge manifold away from the automatic sea discharge valve.

[0014] Furthermore, a 5-degree slope is provided on the discharge manifold from the welded pipe cap side to the automatic sea discharge valve side to allow the natural gas to be discharged smoothly.

[0015] Further, the number of discharge branch pipes below the first low-temperature cofferdam and the second low-temperature cofferdam is greater than the number of discharge branch pipes below the low-temperature collecting plate.

[0016] Furthermore, the height of the cryogenic collecting tray, the first cryogenic cofferdam and the second cryogenic cofferdam is such that their capacity is at least 110% of the leakage of the largest system partition.

[0017] The ultra-low temperature fluid leakage safety disposal system of the offshore steel structure of the present invention has the following advantages: By setting up low-temperature cofferdams and low-temperature collection trays in the central manifold area of ​​the wharf and the unloading area on the wharf side, the leaked liquefied natural gas can be collected, and the automatic sea discharge valve set on the discharge manifold is controlled by a temperature sensor to discharge the liquefied natural gas into the sea. This application collects and discharges the leaked liquefied natural gas to a safe location away from the platform in a timely manner, avoiding the destructive effects of low-temperature liquefied natural gas on the steel structure, equipment and pipelines of the offshore wharf, avoiding injuries to personnel and reducing the risk of fire and explosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The schematic diagram of the ultra-low temperature fluid leakage safety disposal system for offshore steel structures of the present invention is shown.

[0019] Description of the markings in the figure: 1. Central manifold area at the wharf; 2. Unloading area at the first wharf side; 3. Unloading area at the second wharf side; 4. Low-temperature collection tray; 5. First low-temperature cofferdam; 6. Second low-temperature cofferdam; 7. Low-temperature hose; 8. Discharge branch pipe; 9. Welded pipe cap; 10. Discharge manifold; 11. Temperature sensor; 12. Automatic sea discharge valve; 13. Sea discharge port. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0021] Those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present invention and form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.

[0022] Please refer to the attached Figure 1 The invention describes a safe disposal system for ultra-low temperature fluid leakage of an offshore steel structure.

[0023] like Figure 1As shown, the ultra-low temperature fluid leakage safety disposal system of the offshore steel structure in the present invention includes a central manifold area 1 of the wharf and a dock side unloading area, the dock side unloading area is provided with a low temperature cofferdam, and the central manifold area 1 of the wharf is provided with a low temperature collecting tray 4; the low temperature cofferdam and the low temperature collecting tray 4 are both connected to the discharge branch pipe 8 through a low temperature hose 7, the discharge branch pipe 8 is connected to the discharge manifold 10, and the leaked liquefied natural gas is discharged into the sea along the discharge manifold 10; the low temperature cofferdam and the low temperature collecting tray 4 are both provided with a temperature sensor 11, the temperature sensor 11 is connected to the automatic sea discharge valve 12 provided on the discharge manifold 10, and the temperature sensor 11 controls the opening or closing of the automatic sea discharge valve 12.

[0024] By respectively setting up a low-temperature cofferdam and a low-temperature collecting plate 4 in the central manifold area 1 of the wharf and the unloading area on the wharf side, the leaked liquefied natural gas is collected, and the automatic sea discharge valve 12 set on the discharge manifold 10 is controlled by the temperature sensor 11 to discharge the liquefied natural gas into the sea. The present application collects and discharges the leaked liquefied natural gas to a safe location away from the platform in a timely manner, avoiding the destructive effects of low-temperature liquefied natural gas on the steel structure, equipment and pipelines of the offshore wharf, avoiding injuries to personnel and reducing the risk of fire and explosion.

[0025] Further, if Figure 1 As shown, a first wharf side unloading area 2 and a second wharf side unloading area 3 are respectively provided on both sides of the wharf central manifold area 1, and a first low-temperature cofferdam 5 and a second low-temperature cofferdam 6 are respectively provided at the first wharf side unloading area 2 and the second wharf side unloading area 3; a low-temperature hose 7 is connected to the bottom of the low-temperature collecting plate 4, the first low-temperature cofferdam 5 and the second low-temperature cofferdam 6, and the low-temperature hose 7 is welded to the discharge branch pipe 8; the end of the discharge branch pipe 8 away from the low-temperature hose 7 is connected to the discharge manifold 10, and an automatic sea discharge valve 12 is provided on the side of the discharge manifold 10 away from the discharge branch pipe 8.

[0026] In this embodiment, preferably, the two sides of the wharf central manifold area 1 are the first wharf side unloading area 2 and the second wharf side unloading area 3. The wharf central manifold area 1, the first wharf side unloading area 2 and the second wharf side unloading area 3 all have the risk of liquefied natural gas leakage. The wharf central manifold area 1, the first wharf side unloading area 2 and the second wharf side unloading area 3 collect the leaked liquefied natural gas through the low-temperature collection plate 4, the first low-temperature cofferdam 5 and the second low-temperature cofferdam 6 respectively.

[0027] Preferably, the cryogenic collecting tray 4, the first cryogenic cofferdam 5 and the second cryogenic cofferdam 6 can withstand the cold shock within the required time of cryogenic leakage protection, and are heat-insulated from the connected dock structure. A plurality of cryogenic hoses 7 are welded underneath the cryogenic collecting tray 4, the first cryogenic cofferdam 5 and the second cryogenic cofferdam 6. The other ends of the plurality of cryogenic hoses 7 are welded to a plurality of discharge branch pipes 8. The end of the discharge branch pipe 8 away from the cryogenic hose 7 is welded to the discharge manifold 10. The end of the discharge manifold 10 away from the discharge branch pipe 8 is provided with an automatic sea discharge valve 12. By opening the automatic sea discharge valve 12, the leaked liquefied natural gas can be discharged into the sea.

[0028] Further, if Figure 1 As shown, three temperature probes are provided in the low-temperature collecting plate 4, the first low-temperature cofferdam 5 and the second low-temperature cofferdam 6, and the three temperature probes are respectively connected to three temperature sensors 11, so that the temperature sensors 11 control the automatic sea discharge valve 12 to be opened or closed; when at least two of the three temperature sensors 11 receive two low-temperature alarm signals, the automatic sea discharge valve 12 is controlled to be opened; and a welding pipe cap 9 is welded on the end of the discharge manifold 10 away from the automatic sea discharge valve 12.

[0029] In the present embodiment, preferably, three temperature probes are arranged at intervals in the low-temperature collection plate 4, the first low-temperature cofferdam 5 and the second low-temperature cofferdam 6. The three temperature probes are respectively connected to three temperature sensors 11. The temperature changes are identified by the temperature sensors 11, thereby realizing the control of opening or closing of the automatic sea discharge valve 12.

[0030] Moreover, only when at least two of the three temperature sensors 11 receive two low-temperature alarm signals, the automatic sea discharge valve 12 will be opened to realize the sea discharge function; one end of the discharge manifold 10 is used to discharge the leaked liquefied natural gas into the sea, and the other end is welded with a welding pipe cap 9 to achieve the sealing of the discharge manifold 10.

[0031] Further, if Figure 1 As shown, the discharge manifold 10 is provided with a slope of 5 degrees from the side of the welded pipe cap 9 to the side of the automatic sea discharge valve 12 to allow the natural gas to be discharged smoothly; the number of discharge branches 8 below the first cryogenic cofferdam 5 and the second cryogenic cofferdam 6 is greater than the number of discharge branches below the cryogenic collecting tray 4; the enclosure height of the cryogenic collecting tray 4, the first cryogenic cofferdam 5 and the second cryogenic cofferdam 6 meets the requirement that their capacity is at least 110% of the leakage of the maximum system separation part.

[0032] In the present embodiment, preferably, the discharge manifold 10 forms a slope of 5 degrees from one side of the welded pipe cap 9 to the side of the automatic sea discharge valve 12 to avoid accumulation of liquefied natural gas and to discharge it smoothly; according to the actual leakage amount of the liquefied natural gas, a discharge branch pipe 8 of corresponding displacement is matchedly arranged under the cryogenic collecting tray 4, the first cryogenic cofferdam 5 and the second cryogenic cofferdam 6 to discharge the leaked liquefied natural gas smoothly; the enclosure height of the cryogenic collecting tray 4, the first cryogenic cofferdam 5 and the second cryogenic cofferdam 6 satisfies that its capacity is at least 110% of the leakage amount of the maximum system separation part to prevent the liquefied natural gas from leaking along the side walls of the cryogenic collecting tray 4, the first cryogenic cofferdam 5 and the second cryogenic cofferdam 6.

[0033] Preferably, ASPEN HYSYS is used to simulate the potential two-phase flow in the discharge pipe, and the discharge flow rate is calculated according to the LNG leakage amount and duration requirements to obtain the economic pipe diameter of the discharge pipeline and manifold; PHAST is used to simulate the formation range of the liquid pool after the LNG is discharged into the sea and the diffusion of the combustible gas after gasification, so as to determine the location of the safe discharge point.

[0034] The working steps of the ultra-low temperature fluid leakage safety disposal system of the offshore steel structure in this application are as follows: First, the liquefied natural gas leaked from the central manifold area 1 of the terminal is collected by the cryogenic collecting plate 4, and the liquefied natural gas leaked from the first terminal side unloading area 2 and the second terminal side unloading area 3 are collected by the first cryogenic cofferdam 5 and the second cryogenic cofferdam 6; Next, the cryogenic collecting plate 4, the first cryogenic cofferdam 5 and the second cryogenic cofferdam 6 are connected to the discharge manifold 10 through the cryogenic hose 7 and the discharge branch pipe 8, and the leaked liquefied natural gas is discharged into the sea through the discharge port 13 of the discharge manifold 10; Finally, the low-temperature collection plate 4, the first low-temperature cofferdam 5 and the second low-temperature cofferdam 6 are respectively provided with three temperature sensors 11. When two of the three temperature sensors 11 detect a low-temperature alarm signal, the corresponding automatic sea discharge valve 12 will open, thereby realizing the discharge of liquefied natural gas into the sea.

[0035] The ultra-low temperature fluid leakage safety disposal system based on offshore steel structures collects the leaked liquefied natural gas by respectively setting a low temperature collection plate 4, a first low temperature cofferdam 5 and a second low temperature cofferdam 6 in the central manifold area 1 of the wharf, the first wharf side unloading area 2 and the second wharf side unloading area 3, and controls the automatic sea discharge valve 12 set on the discharge manifold 10 through the temperature sensor 11 to discharge the liquefied natural gas into the sea. The present application collects and discharges the leaked liquefied natural gas to a safe location away from the platform in a timely manner, avoiding the destructive effects of low temperature liquefied natural gas on the steel structure, equipment and pipelines of the offshore wharf, avoiding injuries to personnel and reducing the risk of fire and explosion.

[0036] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A safe disposal system for ultra-low temperature fluid leakage of offshore steel structures, characterized in that: It includes the central manifold area of ​​the wharf and the unloading area on the wharf side. The unloading area on the wharf side is equipped with a low-temperature cofferdam, and the central manifold area of ​​the wharf is equipped with a low-temperature collection tray; The cryogenic cofferdam and cryogenic collecting tray are connected to the discharge branch pipe through a cryogenic hose. The discharge branch pipe is connected to the discharge manifold, and the leaked liquefied natural gas is discharged into the sea along the discharge manifold. Temperature sensors are provided on the low-temperature cofferdam and the low-temperature collecting plate. The temperature sensors are connected to the automatic sea discharge valve provided on the discharge manifold. The temperature sensors control the opening or closing of the automatic sea discharge valve.

2. The ultra-low temperature fluid leakage safety disposal system for offshore steel structures according to claim 1 is characterized in that: The first wharf side unloading area and the second wharf side unloading area are respectively arranged on both sides of the central manifold area of ​​the wharf. The first wharf side unloading area and the second wharf side unloading area are respectively provided with the first low-temperature cofferdam and the second low-temperature cofferdam.

3. The ultra-low temperature fluid leakage safety disposal system for offshore steel structures according to claim 2 is characterized in that: Cryogenic hoses are connected to the bottom of the cryogenic collecting plate, the first cryogenic cofferdam and the second cryogenic cofferdam, and the cryogenic hoses are welded to the discharge branch pipe.

4. The ultra-low temperature fluid leakage safety disposal system for offshore steel structures according to claim 3 is characterized in that: One end of the discharge branch pipe away from the low-temperature hose is connected to the discharge manifold, and an automatic sea discharge valve is arranged on the side of the discharge manifold away from the discharge branch pipe.

5. The ultra-low temperature fluid leakage safety disposal system for offshore steel structures according to claim 3 is characterized in that: Three temperature probes are arranged in the low-temperature collecting tray, the first low-temperature cofferdam and the second low-temperature cofferdam. The three temperature probes are respectively connected to three temperature sensors so that the temperature sensors control the opening or closing of the automatic sea discharge valve.

6. The ultra-low temperature fluid leakage safety disposal system for offshore steel structures according to claim 5, characterized in that: When at least two of the three temperature sensors receive two low temperature alarm signals, the automatic sea discharge valve is controlled to open.

7. The ultra-low temperature fluid leakage safety disposal system for offshore steel structures according to claim 4, characterized in that: A welded pipe cap is welded on the end of the discharge manifold away from the automatic sea discharge valve.

8. The ultra-low temperature fluid leakage safety disposal system for offshore steel structures according to claim 7, characterized in that: The discharge manifold is set with a 5-degree slope from the welded pipe cap to the automatic sea valve to allow the natural gas to be discharged smoothly.

9. The ultra-low temperature fluid leakage safety disposal system for offshore steel structures according to claim 3, characterized in that: The number of discharge branch pipes below the first low-temperature cofferdam and the second low-temperature cofferdam is greater than the number of discharge branch pipes below the low-temperature collecting plate.

10. The ultra-low temperature fluid leakage safety disposal system for offshore steel structures according to claim 9, characterized in that: The height of the cryogenic collecting tray, the first cryogenic cofferdam and the second cryogenic cofferdam is such that their capacity is at least 110% of the leakage of the largest system partition.

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