WO2007144458A2 - Method and arrangement for monitoring and detecting leaks from a container - Google Patents

Method and arrangement for monitoring and detecting leaks from a container Download PDF

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Publication number
WO2007144458A2
WO2007144458A2 PCT/FI2007/050276 FI2007050276W WO2007144458A2 WO 2007144458 A2 WO2007144458 A2 WO 2007144458A2 FI 2007050276 W FI2007050276 W FI 2007050276W WO 2007144458 A2 WO2007144458 A2 WO 2007144458A2
Authority
WO
WIPO (PCT)
Prior art keywords
gas
intermediate space
protective wall
container
fluid
Prior art date
Application number
PCT/FI2007/050276
Other languages
French (fr)
Other versions
WO2007144458A3 (en
Inventor
Ari SIPILÄ
Original Assignee
Aker Mtw Werft Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Aker Mtw Werft Gmbh filed Critical Aker Mtw Werft Gmbh
Publication of WO2007144458A2 publication Critical patent/WO2007144458A2/en
Publication of WO2007144458A3 publication Critical patent/WO2007144458A3/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C13/00—Details of vessels or of the filling or discharging of vessels
    • F17C13/12—Arrangements or mounting of devices for preventing or minimising the effect of explosion ; Other safety measures
    • F17C13/126—Arrangements or mounting of devices for preventing or minimising the effect of explosion ; Other safety measures for large storage containers for liquefied gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C13/00—Details of vessels or of the filling or discharging of vessels
    • F17C13/02—Special adaptations of indicating, measuring, or monitoring equipment
    • F17C13/025—Special adaptations of indicating, measuring, or monitoring equipment having the pressure as the parameter
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C3/00—Vessels not under pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17D—PIPE-LINE SYSTEMS; PIPE-LINES
    • F17D5/00—Protection or supervision of installations
    • F17D5/02—Preventing, monitoring, or locating loss
    • F17D5/04—Preventing, monitoring, or locating loss by means of a signalling fluid enclosed in a double wall
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M3/00—Investigating fluid-tightness of structures
    • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
    • G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
    • G01M3/16—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using electric detection means
    • G01M3/18—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using electric detection means for pipes, cables or tubes; for pipe joints or seals; for valves; for welds; for containers, e.g. radiators
    • G01M3/186—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using electric detection means for pipes, cables or tubes; for pipe joints or seals; for valves; for welds; for containers, e.g. radiators for containers, e.g. radiators
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M3/00—Investigating fluid-tightness of structures
    • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
    • G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
    • G01M3/20—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material
    • G01M3/22—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material for pipes, cables or tubes; for pipe joints or seals; for valves; for welds; for containers, e.g. radiators
    • G01M3/226—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material for pipes, cables or tubes; for pipe joints or seals; for valves; for welds; for containers, e.g. radiators for containers, e.g. radiators
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M3/00—Investigating fluid-tightness of structures
    • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
    • G01M3/26—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors
    • G01M3/32—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for containers, e.g. radiators
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M3/00—Investigating fluid-tightness of structures
    • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
    • G01M3/26—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors
    • G01M3/32—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for containers, e.g. radiators
    • G01M3/3236—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for containers, e.g. radiators by monitoring the interior space of the containers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M3/00—Investigating fluid-tightness of structures
    • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
    • G01M3/26—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors
    • G01M3/32—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for containers, e.g. radiators
    • G01M3/3236—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for containers, e.g. radiators by monitoring the interior space of the containers
    • G01M3/3272—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for containers, e.g. radiators by monitoring the interior space of the containers for verifying the internal pressure of closed containers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2201/00—Vessel construction, in particular geometry, arrangement or size
    • F17C2201/05—Size
    • F17C2201/052—Size large (>1000 m3)
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2203/00—Vessel construction, in particular walls or details thereof
    • F17C2203/01—Reinforcing or suspension means
    • F17C2203/011—Reinforcing means
    • F17C2203/012—Reinforcing means on or in the wall, e.g. ribs
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2203/00—Vessel construction, in particular walls or details thereof
    • F17C2203/03—Thermal insulations
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2203/00—Vessel construction, in particular walls or details thereof
    • F17C2203/06—Materials for walls or layers thereof; Properties or structures of walls or their materials
    • F17C2203/0602—Wall structures; Special features thereof
    • F17C2203/0612—Wall structures
    • F17C2203/0626—Multiple walls
    • F17C2203/0629—Two walls
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2205/00—Vessel construction, in particular mounting arrangements, attachments or identifications means
    • F17C2205/03—Fluid connections, filters, valves, closure means or other attachments
    • F17C2205/0302—Fittings, valves, filters, or components in connection with the gas storage device
    • F17C2205/0323—Valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2205/00—Vessel construction, in particular mounting arrangements, attachments or identifications means
    • F17C2205/03—Fluid connections, filters, valves, closure means or other attachments
    • F17C2205/0302—Fittings, valves, filters, or components in connection with the gas storage device
    • F17C2205/0338—Pressure regulators
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2221/00—Handled fluid, in particular type of fluid
    • F17C2221/03—Mixtures
    • F17C2221/032—Hydrocarbons
    • F17C2221/033—Methane, e.g. natural gas, CNG, LNG, GNL, GNC, PLNG
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2223/00—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel
    • F17C2223/01—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel characterised by the phase
    • F17C2223/0146—Two-phase
    • F17C2223/0153—Liquefied gas, e.g. LPG, GPL
    • F17C2223/0161—Liquefied gas, e.g. LPG, GPL cryogenic, e.g. LNG, GNL, PLNG
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2223/00—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel
    • F17C2223/03—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel characterised by the pressure level
    • F17C2223/033—Small pressure, e.g. for liquefied gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2250/00—Accessories; Control means; Indicating, measuring or monitoring of parameters
    • F17C2250/03—Control means
    • F17C2250/032—Control means using computers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2250/00—Accessories; Control means; Indicating, measuring or monitoring of parameters
    • F17C2250/04—Indicating or measuring of parameters as input values
    • F17C2250/0404—Parameters indicated or measured
    • F17C2250/043—Pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2250/00—Accessories; Control means; Indicating, measuring or monitoring of parameters
    • F17C2250/04—Indicating or measuring of parameters as input values
    • F17C2250/0404—Parameters indicated or measured
    • F17C2250/0447—Composition; Humidity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2250/00—Accessories; Control means; Indicating, measuring or monitoring of parameters
    • F17C2250/04—Indicating or measuring of parameters as input values
    • F17C2250/0404—Parameters indicated or measured
    • F17C2250/0447—Composition; Humidity
    • F17C2250/0452—Concentration of a product
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2260/00—Purposes of gas storage and gas handling
    • F17C2260/03—Dealing with losses
    • F17C2260/035—Dealing with losses of fluid
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2260/00—Purposes of gas storage and gas handling
    • F17C2260/03—Dealing with losses
    • F17C2260/035—Dealing with losses of fluid
    • F17C2260/036—Avoiding leaks
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2270/00—Applications
    • F17C2270/01—Applications for fluid transport or storage
    • F17C2270/0102—Applications for fluid transport or storage on or in the water
    • F17C2270/0105—Ships
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2270/00—Applications
    • F17C2270/01—Applications for fluid transport or storage
    • F17C2270/0134—Applications for fluid transport or storage placed above the ground

Definitions

  • the invention relates to a method of monitoring and detecting leaks of fluid or gas of a container according to the preamble of claim 1 .
  • the invention relates also to the arrangement for applying the method according to the preamble of claim 5.
  • LNG liquefied natural gas
  • membrane tanks supported to the hull structure or self-supported spherical or prismatic tanks are usually used.
  • Aluminium and/or its alloys are with advantage used due to their strength and weight properties. Due to the very low temperatures of cryogenic liquefied gases, such as typically ethylene (LEG) - 103 5 C or natural gas (LNG) -163 5 C, the demands are high as regards the strength and quality of the container. High demands apply as well for safety aspects and detection of possible leaks, since the mediums in the containers can be inflammable, explosive or toxic. For detection of leaks it is known to make use of some suitable inert gas.
  • the container structure of the kind described above constitutes a uniform strength structure with two tight container surfaces, i.e. the primary and the secondary barriers, in case of fatigue fractures in the outer container surface there are no leaks of fluid or gas through the inner container surface. Notwithstanding, the fracture may compromise the overall strength of the container. Therefore it is of importance to monitor the condition and possible leaks in both the container walls independently.
  • the invention aims to provide an improved method and arrangement for continuously monitoring and detecting leaks of fluid or gas of a self-supporting container including two separate barriers and constituting a uniform strength structure suitable for storing and transporting of fluid in the form of at least liquefied natural gas or the like cryogenic gas in order to thereby solve the above described problems and defects in the prior art.
  • a further aim is to provide for cost effective solution and easy way of locating the leaks and defective positions in the walls.
  • the method includes a first mode including the steps of supplying inert gas into the intermediate space and then feeding said in- ert gas into a detection means for detection of hydrocarbons possibly leaked through the first protective wall, and a second mode including the steps of increasing the pressure in the intermediate space at most to the level of the pressure prevailing inside of the first protective wall and then monitoring the level of pressure in the intermediate space.
  • a first mode including the steps of supplying inert gas into the intermediate space and then feeding said in- ert gas into a detection means for detection of hydrocarbons possibly leaked through the first protective wall
  • a second mode including the steps of increasing the pressure in the intermediate space at most to the level of the pressure prevailing inside of the first protective wall and then monitoring the level of pressure in the intermediate space.
  • the intermediate space is with advantage divided by means of the intermediate members into sections gas-tightly isolated from each other. Then the method may be applied to these separate sections independently making it easier to detect the exact location of a possible leak.
  • a number of separate sections may be provided with individual inlet and outlet pipe means whereby said pipe means of separate sections can be alternatingly connected to gas supplying means and detection means provided in common.
  • the number of separate devices can with advantage be reduced.
  • the reference numeral 1 indicates a container including a first wall 2 and a second wall 3 fixed together by means of a number of intermediate ribs 5 dividing the intermediate space between the walls 2 and 3 to independent sections 6, 7 and 8 gas-tightly isolated from each other.
  • the walls 2 and 3 form a first and a second barrier of the container enclosing a space 4 filled with LNG or the like cryogenic gas.
  • the container is provided with a main feeding pipe 9 for supplying inert gas, preferably nitrogen, independently through branch pipes 9a, 9b and 9c into each of the sections 6-8.
  • the sections are additionally provided with outlet pipes 10a, 10b and 10c respec- tively which are led in a first mode of the invention to a gas analyser 1 1 for detecting of any hydrocarbons which are a clear indication of a leak in the first protective wall 2.
  • the gas analyser 1 1 may be either separately connected to each of the sections or alternatingly connected to either one of them by utilising the valves 15.
  • separate analysers 1 1 may be used for each section or a group of sections
  • the main feeding pipe 9 is provided with a branch pipe 9' including a compressor 14 for temporarily increasing the pressure of the inert gas in the sections 6-8.
  • the increased pressure must not exceed the pressure prevailing inside the container in the space 4 so that a possible leak in any one of the sections 6-8 will result in a decrease of pressure in the pipes 10a, 10b or 10c which is detected by the pressure gauges 16.
  • the pipes are closed by means of valves 17 to prevent the increased pressure to act on the analyser 1 1 .
  • the space 4 is provided with a pressure gauge 16 for comparison.
  • the invention can be applied to practically any container design including a first and a second barrier and constituting a self-supporting uniform strength structure.
  • the solution is feasible likewise for stationery land applications or maritime applications.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Examining Or Testing Airtightness (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)

Abstract

The invention relates to a method and arrangement for monitoring and detecting leaks of fluid or gas of a container (1) filled with fluid in the form of liquefied natural gas or the like cryogenic gas including hydrocarbons, said container comprising at least a first (2) and a second (3) protective wall being spaced apart and fixed to each other by means of intermediate members (5) leaving a gas tight intermediate space between the walls (2,3), the fluid being inside of the first protective wall (2). The method includes a first mode including the steps of supplying inert gas into the intermediate space (6,7,8) and then feeding said inert gas into a 10 detection means (11) for detection of hydrocarbons possibly leaked through the first protective wall (2), and a second mode including the steps of increasing the pressure in the intermediate space (6,7,8) at most to the level of the pressure prevailing inside of the first protective wall (2) and then monitoring the level of pressure in the intermediate space. Further according to the invention these two modes are utilised in turns.

Description

METHOD AND ARRANGEMENT FOR MONITORING AND DETECTING LEAKS FROM A CONTAINER
Technical field
The invention relates to a method of monitoring and detecting leaks of fluid or gas of a container according to the preamble of claim 1 . The invention relates also to the arrangement for applying the method according to the preamble of claim 5.
Background art
In principle structures of different kinds can be utilised for storing and transporting fluids, specifically liquefied natural gas (LNG). Especially for transportation in ships either membrane tanks supported to the hull structure or self-supported spherical or prismatic tanks are usually used. Aluminium and/or its alloys are with advantage used due to their strength and weight properties. Due to the very low temperatures of cryogenic liquefied gases, such as typically ethylene (LEG) - 1035C or natural gas (LNG) -1635C, the demands are high as regards the strength and quality of the container. High demands apply as well for safety aspects and detection of possible leaks, since the mediums in the containers can be inflammable, explosive or toxic. For detection of leaks it is known to make use of some suitable inert gas.
As regards maritime applications regulations are given by IMO (International Maritime Organisation). In accordance with the regulations the storage facilities for LNG or the like substances should have i.a. a primary and a secondary barrier. When self-supporting containers are concerned a suitable container structure in this respect is disclosed in the document US 3246789. This known construction includes the required two separate barriers and additionally provides for a uniform strength structure suitable both for land and maritime applications. This document teaches the use of inert gas in the cells or cavities formed between the inner and outer walls of the container for testing it for gas-tightness. In addition these cells serve to admit gas into the hollow walls during cooling-off of the cargo to com- pensate for lowering of the gas pressure inside the container. There is no suggestion, however, for continuous monitoring of leaks during the actual storing phases.
Since the container structure of the kind described above constitutes a uniform strength structure with two tight container surfaces, i.e. the primary and the secondary barriers, in case of fatigue fractures in the outer container surface there are no leaks of fluid or gas through the inner container surface. Notwithstanding, the fracture may compromise the overall strength of the container. Therefore it is of importance to monitor the condition and possible leaks in both the container walls independently.
On the basis of the above the invention aims to provide an improved method and arrangement for continuously monitoring and detecting leaks of fluid or gas of a self-supporting container including two separate barriers and constituting a uniform strength structure suitable for storing and transporting of fluid in the form of at least liquefied natural gas or the like cryogenic gas in order to thereby solve the above described problems and defects in the prior art. A further aim is to provide for cost effective solution and easy way of locating the leaks and defective positions in the walls.
The aims of the invention are met substantially as is disclosed in claims 1 and 5 and in the other claims.
Disclosure of the invention
In accordance with the invention the method includes a first mode including the steps of supplying inert gas into the intermediate space and then feeding said in- ert gas into a detection means for detection of hydrocarbons possibly leaked through the first protective wall, and a second mode including the steps of increasing the pressure in the intermediate space at most to the level of the pressure prevailing inside of the first protective wall and then monitoring the level of pressure in the intermediate space. These two modes are then utilised in turns. Hereby it is possible to monitor and detect possible faults and leaks in both the walls and additionally find out whether the question is about the first or the second protective wall or barrier. Basically the same inlet and outlet appliances for the inert gas can be utilised for both modes of the method. The method is available for land as well as maritime applications and it is independent of the actual form of the container, i.e. whether prismatic or spherical or some combination thereof.
In practice the intermediate space is with advantage divided by means of the intermediate members into sections gas-tightly isolated from each other. Then the method may be applied to these separate sections independently making it easier to detect the exact location of a possible leak. For this purpose a number of separate sections may be provided with individual inlet and outlet pipe means whereby said pipe means of separate sections can be alternatingly connected to gas supplying means and detection means provided in common. Hereby the number of separate devices can with advantage be reduced.
In practice it is of advantage to use nitrogen as the inert gas, since it is easily available and serves well for the purpose.
Brief Description of Drawings
In the following the invention will be illustrated and described as a way of exam- pie only with reference to the only accompanying schematic drawing, in which a part of a container with the monitoring and detection arrangements related thereto are depicted.
Best mode for carrying out the invention
In the drawing the reference numeral 1 indicates a container including a first wall 2 and a second wall 3 fixed together by means of a number of intermediate ribs 5 dividing the intermediate space between the walls 2 and 3 to independent sections 6, 7 and 8 gas-tightly isolated from each other. Although for practical reasons only a part of the wall structure and the sections has been shown, in prac- tice the whole container can be similarly constructed and forms a self-supporting structure.
The walls 2 and 3 form a first and a second barrier of the container enclosing a space 4 filled with LNG or the like cryogenic gas. In order to monitor continuously the gas-tightness of the container and to locate possible fractures or the like faults resulting in leaks in either one of the protective walls 2 or 3 the container is provided with a main feeding pipe 9 for supplying inert gas, preferably nitrogen, independently through branch pipes 9a, 9b and 9c into each of the sections 6-8. The sections are additionally provided with outlet pipes 10a, 10b and 10c respec- tively which are led in a first mode of the invention to a gas analyser 1 1 for detecting of any hydrocarbons which are a clear indication of a leak in the first protective wall 2. Depending on the arrangement in each case the gas analyser 1 1 may be either separately connected to each of the sections or alternatingly connected to either one of them by utilising the valves 15. Naturally, also separate analysers 1 1 may be used for each section or a group of sections
Independent on whether or not there is a leak in the first protective wall 2 it is of importance to monitor also possible leaks in the second protective wall 3, since the container constituting a uniform strength structure possible fractures or other faults in the second wall 3 may affect also the overall strength of the container. Therefore a second mode is available. For this purpose the main feeding pipe 9 is provided with a branch pipe 9' including a compressor 14 for temporarily increasing the pressure of the inert gas in the sections 6-8. The increased pressure must not exceed the pressure prevailing inside the container in the space 4 so that a possible leak in any one of the sections 6-8 will result in a decrease of pressure in the pipes 10a, 10b or 10c which is detected by the pressure gauges 16. For this purpose the pipes are closed by means of valves 17 to prevent the increased pressure to act on the analyser 1 1 . In addition the space 4 is provided with a pressure gauge 16 for comparison.
After a suitable period of time the whole arrangement will be changed again to correspond to the first mode of monitoring and detecting. In this case the branch pipe 9' through the compressor 14 is cut off with valves 18 and the extra pressure in the sections 6-8 is relieved by temporarily opening the valves 12. Then the valves 12 are closed again and the valves 17 are opened to reconnect the sections 6-8 with the analyser 1 1 .
By utilising in turns the two different modes described above it is possible to monitor and detect possible leaks in either one of the protective walls 2 or 3 inde- pendently. The invention can be applied to practically any container design including a first and a second barrier and constituting a self-supporting uniform strength structure. The solution is feasible likewise for stationery land applications or maritime applications.
The invention is not limited to the embodiment described above but can be im- plemented in many other different embodiments within the scope of the inventive idea defined in the attached claims.

Claims

Claims
1 . A method of monitoring and detecting leaks of fluid or gas of a container (1 ) filled with fluid in the form of liquefied natural gas or the like cryogenic gas including hydrocarbons, said container comprising at least a first (2) and a second (3) protective wall being spaced apart and fixed to each other by means of intermediate members (5) leaving a gas tight intermediate space between the walls (2,3), the fluid being inside of the first protective wall (2), characterised in that the method includes a first mode including the steps of supplying inert gas into the intermediate space and then feeding said inert gas into a detection means (1 1 ) for detection of hydrocarbons possibly leaked through the first protective wall (2), and a second mode including the steps of increasing the pressure in the intermediate space (6,7,8) at most to the level of the pressure prevailing inside of the first protective wall (2) and then monitoring the level of pressure in the intermediate space, and in that these two modes are utilised in turns.
2. A method according to claim 1 , characterised in that the intermediate space is divided by means of the intermediate members (5) into sections (6,7,8) gas-tightly isolated from each other and in that the method is applied to these separate sections (6,7,8) independently.
3. A method according to claim 2, characterised in that a number of separate sections (6,7,8) are provided with individual inlet (9a,9b,9c) and outlet
(10a,10b,10c) pipe means and in that said pipe means of separate sections are alternatingly connected to gas supplying means (9) and detection means (1 1 ) provided in common.
4. A method according to any one of the preceding claims, characterised in that nitrogen is utilised as the inert gas.
5. An arrangement for monitoring and detecting leaks of fluid or gas of a container (1 ) filled with fluid in the form of liquefied natural gas or the like cryogenic gas including hydrocarbons, said container comprising at least a first (2) and a second (3) protective wall being spaced apart and fixed to each other by means of intermediate members (5) leaving a gas tight intermediate space between the walls (2,3), the fluid being inside of the first protective wall (2), characterised in that it includes means (9) for supplying inert gas into the intermediate space and detection means (1 1 ) for detection of hydrocarbons, said inert gas in the intermediate space being arranged to be fed into said detection means (1 1 ) for detecting hydrocarbons possibly leaked through the first protective wall, and that it further includes means (14) for temporarily increasing the pressure in the intermediate space at most to the level of the pressure prevailing inside of the first protective wall (2) and means for monitoring (16) the level of pressure in the intermediate space for detecting possible leaks through said second protective wall (3), and in that the gas supplying means (9) and the detection means (1 1 ) and on the other hand the gas pressure increasing means (14, 9' and 9) are utilised in turns.
6. An arrangement according to claim 5, characterised in that the intermediate space is divided by means of the intermediate members (5) into sections (6,7,8) gas-tightly isolated from each other and in that a number of separate sections (6,7,8) are arranged to be monitored independently.
7. An arrangement according to claim 6, characterised in that a number of separate sections (6,7,8) are provided with individual inlet (9a,9b,9c) and outlet (10a,10b,10c) pipe means and in that said pipe means of separate sections are alternatingly arranged to be connected to gas supplying means (9) and detection means (1 1 ) provided in common.
8. An arrangement according to any one of the preceding claims 5 -7, characterised in that gas analyser (1 1 ) of the type catalytic combustion is utilised as detection means (1 1 ).
9. An arrangement according to any one of the preceding claims 5 -7, characterised in that the inert gas is nitrogen.
PCT/FI2007/050276 2006-06-16 2007-05-15 Method and arrangement for monitoring and detecting leaks from a container WO2007144458A2 (en)

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WO2010139914A1 (en) 2009-06-05 2010-12-09 Gaztransport Et Technigaz Multi-membrane reservoir sealing test
FR2952715A1 (en) * 2009-11-13 2011-05-20 Gaztransp Et Technigaz Method for locating leakages of tank e.g. liquefied natural gas or methane tank, involves generating depression in space with respect to interior of tank, applying liquid film on front face of membrane, and detecting cold points of membrane
WO2011121415A1 (en) * 2010-03-29 2011-10-06 Kajtar Mate High-precision leak detection in underground storage tanks
EP2853875A1 (en) * 2013-09-30 2015-04-01 Werkzeugbau Siegfried Hofmann GmbH Device for the early detection of the formation of fissures in media-conveying workpieces

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FR2042934A5 (en) * 1969-04-04 1971-02-12 Mac Mullen John Associat
FR2221687A1 (en) * 1973-03-17 1974-10-11 Mitsubishi Heavy Ind Ltd
FR2234513A1 (en) * 1973-06-21 1975-01-17 Mitsubishi Heavy Ind Ltd
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010139914A1 (en) 2009-06-05 2010-12-09 Gaztransport Et Technigaz Multi-membrane reservoir sealing test
FR2952715A1 (en) * 2009-11-13 2011-05-20 Gaztransp Et Technigaz Method for locating leakages of tank e.g. liquefied natural gas or methane tank, involves generating depression in space with respect to interior of tank, applying liquid film on front face of membrane, and detecting cold points of membrane
WO2011121415A1 (en) * 2010-03-29 2011-10-06 Kajtar Mate High-precision leak detection in underground storage tanks
EP2853875A1 (en) * 2013-09-30 2015-04-01 Werkzeugbau Siegfried Hofmann GmbH Device for the early detection of the formation of fissures in media-conveying workpieces
US9568393B2 (en) 2013-09-30 2017-02-14 Werkzeugbau Siegfried Hofmann Gmbh Method and device for the early detection of crack formations in media-carrying workpieces

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FI20065411L (en) 2007-12-17
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