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EP-4445113-B1 - VARIABLE VOLUME AND VARIABLE PRESSURE SAMPLING CONTAINER

EP4445113B1EP 4445113 B1EP4445113 B1EP 4445113B1EP-4445113-B1

Inventors

  • BARERE, PIERRE

Dates

Publication Date
20260513
Application Date
20221201

Claims (15)

  1. A method of capturing a sample of cryogenic liquid in a variable volume and variable pressure sampling container (1), the method comprising: inserting a variable volume and variable pressure sampling container (1) into a thermally insulated vacuum enclosure (210), the container (1) comprising a bellows receptacle (3) comprising an inlet valve (4) and an outlet valve (5), and a pressurised external chamber (2) surrounding the bellows receptacle (3), and connecting the inlet valve (4) of the container (1) to a process pipeline containing cryogenic liquid and the outlet valve (5) of the container (1) to vent or boil-off-gas; maintaining a first pressure (P ec1 ) within the pressurised external chamber (2) during capture of a sample of cryogenic liquid, the first pressure (P ec1 ) being greater than a second pressure (P c ) within the bellows receptacle (3) to maintain the bellows receptacle (3) in a compressed state; opening the inlet valve (4) and the outlet valve (5) of the container (1); cooling the bellows receptacle (3) of the container (1) from a first temperature to a second temperature, wherein the second temperature is a temperature of the cryogenic liquid in the process pipeline, by flowing the cryogenic liquid from the process pipeline into the bellows receptacle (3) through the inlet valve (4) and out of the bellows receptacle (3) through the outlet valve (5); determining that the cryogenic liquid flowing out of the outlet valve (5) is in a liquid phase; and closing the inlet valve (4) and the outlet valve (5) to capture a sample of cryogenic liquid in the bellows receptacle of the container (1).
  2. The method of claim 1, further comprising: gradually breaking the vacuum in the enclosure to gradually increase the temperature of the captured sample and the temperature of the bellows receptacle from the second temperature to an ambient temperature, wherein the ambient temperature is greater than a boiling point temperature of the cryogenic liquid.
  3. The method of claim 2, wherein as the temperature of the bellows receptacle exceeds the boiling point temperature of the cryogenic liquid, the method further comprises: vaporizing the captured sample within the bellows receptacle, such that the captured sample transitions from the liquid phase to a gas phase within the bellows receptacle, causing the bellows receptacle to expand.
  4. The method of claim 3, wherein vaporization of the captured sample within the bellows receptacle (3) increases the pressure within the bellows receptacle (3) from the second pressure (P c ) to a third pressure (P d ) and increases the pressure within the external chamber (2) from the first pressure (P ec1 ) to a fourth pressure (P ec2 ), the method further comprising: counterbalancing the increased pressure (P d ) within the bellows receptacle (3) with the increased pressure (P ec2 ) within the external chamber (2).
  5. The method of claim 3 or claim 4, further comprising: removing the container from the enclosure when the temperature of the captured sample and the temperature of the bellows receptacle has increased to the ambient temperature.
  6. The method of any preceding claim, further comprising: storing the captured sample in the gas phase within the bellows receptacle of the container.
  7. The method of any preceding claim, wherein the inlet valve is connected to the process pipeline though a vacuum insulated take-off probe.
  8. The method of any preceding claim, wherein the vent or boil-off-gas is at or near atmospheric pressure.
  9. The method of any preceding claim, wherein the ambient temperature comprises room temperature.
  10. A variable volume and variable pressure sampling container (1) for capturing a sample of cryogenic liquid, the container (1) comprising: a bellows receptacle (3) comprising an inlet valve (4) and an outlet valve (5), wherein, in use, a sample of cryogenic liquid flows into the bellows receptacle (3) through the inlet valve (4) and is captured in the bellows receptacle (3); and a pressurised external chamber (2) surrounding the bellows receptacle (3), wherein, a pressure within the pressurised external chamber (2) is maintained at a first pressure (P ec1 ), the first pressure (P ec1 ) being greater than a second pressure (P c ) within the bellows receptacle (3) and a process pressure of the cryogenic liquid to maintain the bellows receptacle (3) in a compressed state during capture of the sample of cryogenic liquid in the bellows receptacle (3).
  11. The container of claim 10, further comprising: an inlet connection between the inlet valve (4) and the bellows receptacle (3); and an outlet connection between the outlet valve (5) and the bellows receptacle (3); wherein changing a size of the inlet connection and the outlet connection changes an internal volume of the bellows receptacle (3).
  12. The container of claim 10 or claim 11, wherein the bellows receptacle (3) is configured to capture between 6 - 8 cm 3 of the cryogenic liquid.
  13. The container of any one of claims 10 to 12, wherein the bellows receptacle (3) is configured to expand to an expanded state within the pressurised external chamber (2) when the captured sample of cryogenic liquid vaporises and transitions from liquid phase to gas phase within the bellows receptacle (3), and wherein the second pressure (P c ) within the bellows receptacle (3) increases to a third pressure (P d ) and the first pressure (P ec1 ) within the external chamber (2) increases to a fourth pressure (P ec2 ) when the sample vaporises and wherein the fourth pressure (P ec2 ) within the external chamber (2) counterbalances the third pressure (P d ) within the bellows receptacle (3) as the sample vaporises.
  14. The container of any one of claims 10 to 13, further comprising: a bellows receptacle pressure transmitter configured to measure the pressure within the bellows receptacle (3) and an external chamber pressure transmitter configured to measure the pressure within the external chamber (2).
  15. A thermally insulated vacuum enclosure comprising: the container of any one of claims 10 to 14; a flow indicator for determining a liquid phase of the sample; a viscosity detector for determining a viscosity of the sample; and a vacuum pump configured to create a vacuum within the vacuum enclosure, wherein the container is removable from the enclosure.

Description

The present techniques relate to the field of capturing and storing samples of cryogenic liquids. The present techniques also relate to the field of accumulating and storing grab samples of natural gas. More particularly, the techniques relate to a variable volume and variable pressure sampling container for: capturing samples of cryogenic liquids and storing the samples in the same container; or accumulating grab samples of natural gas and storing the samples in the same container. A known liquefied natural gas (LNG) spot sampling device is disclosed in "GIIGNL HANDBOOK" publication number 6, at paragraph 6.9, dated May 2021. A quantity of LNG from a process line is injected into a chamber, which had previously been cooled down by LNG circulation, to partially fill the chamber with LNG. The chamber is then isolated. The LNG sample is brought to ambient temperature and vaporises, so that the regasified LNG fills the whole volume of the chamber, the chamber being designed to withstand the pressure increase. Gas samples are then withdrawn from the chamber via a pressure reducing valve to fill gas sampling containers. Disadvantages associated with above-described LNG spot sampling device are: the gas sample to be withdrawn via the sampling container requires complex purging and filling procedures to preserve the integrity of the sample; andit is hard to control precisely the quantity of LNG injected into the chamber. A known device for accumulating and storing grab samples of natural gas is disclosed in ISO 8943 2017 entitled: Refrigerated light hydrocarbon fluids - Sampling of liquefied natural gas - Continuous and intermittent methods. Figure 3 of ISO 8943 2017 illustrates a pump or compressor item 10 generating gas sample grabs which are accumulated in a piston cylinder under constant pressure conditions. The constant pressure/floating piston (CP) cylinder is counterbalanced by pressure from pre-charged helium in the opposite chamber. A disadvantage associated with a constant pressure container constituted by a piston cylinder is: the sample expansion in one side of the piston is required to be counterbalanced by a neutral gas in the other side of the piston, however because the moving piston requires seals and grease, it does not have absolute tightness. Further related devices and methods are known from WO 2019/144791 A1 and US 2018/0283994 A1. A sampling method and container according to the present invention are defined by claims 1 and 10. According to a first technique, there is provided variable volume and variable pressure sampling container. The container comprises a bellows receptacle comprising an inlet valve and an outlet valve; and a pressurised external chamber surrounding the bellows receptacle and configured to maintain the bellows receptacle in a compressed state when a pressure within the external chamber is greater than a pressure within the bellows receptacle. The container of the first technique may further comprise an inlet connection between the inlet valve and the bellows receptacle; and an outlet connection between the outlet valve and the bellows receptacle; wherein changing a size of the inlet connection and the outlet connection changes an internal volume of the bellows receptacle. The bellows receptacle of the container of the first technique may be configured to capture a sample of cryogenic liquid in liquid phase when in the compressed state, wherein the sample enters the bellows receptacle through the inlet valve. A temperature of the bellows receptacle of the container of the first technique may be the same as a temperature of the sample of cryogenic liquid when the sample of cryogenic liquid is captured in the bellows receptacle. The bellows receptacle of the container of the first technique may be configured to prevent the sample of cryogenic liquid from leaking out of the bellows receptacle. The bellows receptacle of the container of the first technique may be configured to expand to an expanded state within the pressurised external chamber when the captured sample of cryogenic liquid vaporises and transitions from the liquid phase to a gas phase within the bellows receptacle, and wherein the pressure within the bellows receptacle and the pressure within the external chamber both increase when the sample vaporises. The bellows receptacle of the container of the first technique may be configured to expand to a fully expanded state when all of the sample of cryogenic liquid has vaporised. The external chamber of the container of the first technique may be configured so that the increased pressure within the external chamber counterbalances the increased pressure within the bellows receptacle when the sample vaporises. The bellows receptacle of the container of the first technique may be further configured to store the sample in the gas phase in the expanded state. The bellows receptacle of the container of the first technique may be configured to capture the sample of the cr