Liquefied gas storage and vaporization process
The vaporization line with a strainer and oriented downstream end effectively addresses incomplete vaporization in cryogenic tanks by enhancing heat exchange, ensuring complete gas vaporization and efficient gas usage.
Patent Information
- Application Number
- FR2021014092
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2021-12-21
- Publication Date
- 2025-12-26
- Estimated Expiration
- 2041-12-21
AI Technical Summary
Existing methods for vaporizing liquefied gases in tanks, particularly in cryogenic installations with high-performance thermal insulation, often fail to completely vaporize the gas, leaving residual liquid at the lowest point due to inefficient heat distribution, especially when the tank lacks a liquid drain line.
A vaporization line with a downstream end positioned near the tank's bottom and oriented towards it, combined with a strainer to divide the gas flow into multiple jets, ensures thorough vaporization by injecting heated gas at a temperature higher than the liquefaction temperature, optimizing heat exchange and ensuring complete vaporization.
This method ensures complete vaporization of liquefied gases within a reasonable timeframe without residual liquid, optimizing gas usage and maintaining safety in hazardous environments.
Smart Images
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Abstract
Description
Title of the invention: Liquefied gas reservoir and vaporization process
[0001] The invention relates to a liquefied gas reservoir and a vaporization method in such a reservoir.
[0002] The invention relates more particularly to a liquefied gas tank, in particular hydrogen, comprising a sealed casing delimiting a storage volume for liquefied gas between a lower bottom and an upper end, a thermal insulation system arranged around the casing and a set of fluid transfer pipe(s) opening into the casing.
[0003] For maintenance reasons, for example, it may be necessary to empty liquefied gas tanks by vaporization. This is particularly important in the case of toxic or otherwise hazardous gases, for which it is essential to be absolutely certain that there is no trace of liquid left in the installation before opening any pipes for maintenance.
[0004] Completely vaporizing a liquefied gas in a tank within a reasonable timeframe, that is, without waiting for the liquid to vaporize using thermal inlets, can be relatively complex, particularly in the case of a cryogenic installation with high-performance thermal insulation. This is all the more problematic when the tank does not have a liquid drain line at the bottom.
[0005] There are solutions that involve introducing hot gas into the tank to gradually vaporize the liquid. For example, a closed loop of hot gas is used for heat exchange within the tank: the gas heats up outside the cryogenic section and then gradually heats the fluid in the system.
[0006] Similarly, a sweep with a hot gas can be carried out in the pipes (gas at ambient temperature or heated to several tens of degrees for example).
[0007] These known technical solutions do not allow for the complete vaporization of the liquefied gas. It is common for a puddle to remain at the lowest point.
[0008] One object of the present invention is to overcome all or part of the disadvantages of the prior art noted above.
[0009] To this end, the reservoir according to the invention, which otherwise conforms to the generic definition given in the preamble above, is essentially characterized in that the transfer line assembly comprises a vaporization line having an upstream end intended to be connected to a source of heating gas and a downstream end opening into the lower part of the envelope near the bottom of the envelope and oriented towards the bottom.
[0010] Furthermore, embodiments of the invention may include one or more of the following features: - the downstream end of the vaporization line opens at a distance from the bottom of the casing greater than zero millimeters and less than three times the diameter of the vaporization line, - The downstream end of the vaporization pipe is fitted with a strainer that subdivides the gas flow into several distinct jets. - the vaporization pipe passes through the casing via the bottom of the casing from bottom to top and is bent within the casing towards the bottom, - the tank includes a heating element for the gas flow transported by the vaporization line,
[0011] The invention also relates to a method of vaporizing liquefied gas contained in a tank according to any one of the above or below characteristics, comprising a step of injecting a heating gas into the shell via the vaporization line, the heating gas having a temperature higher than the liquefaction temperature of the liquefied gas.
[0012] According to other possible features: - the injection step is maintained until complete vaporization of the liquefied gas contained in the envelope, and / or until the temperature at the bottom of the envelope is higher than the liquefaction temperature of the liquefied gas, - the liquefied gas is one of: hydrogen, CO, any toxic or flammable gas and in that the vaporization gas comprises at least one of: nitrogen, a gas identical to that to be vaporized, dry air.
[0013] The invention may also relate to any alternative device or method comprising any combination of the above or below features within the scope of the claims.
[0014] Other features and advantages will become apparent from the following description, made with reference to the figures in which:
[0015] [Fig-1] represents a schematic and partial vertical cross-sectional view, illustrating a example of the structure and operation of a tank and method according to the invention.
[0016] The liquefied gas tank 1, in particular hydrogen or CO, illustrated includes a sealed enclosure 2 delimiting a storage volume for liquefied gas.
[0017] The reservoir 1 can, for example, be cylindrical or spherical or of any other shape comprising a lower bottom and an upper end.
[0018] The tank 1 includes a thermal insulation system 3 arranged around the envelope 2. For example, a double-walled structure 2, 4 with thermal insulation 3 between the two walls 2, 4.
[0019] The tank 1 includes a set of fluid transfer pipe(s) opening into the shell 2 and in particular a vaporization pipe 7 comprising an upstream end intended to be connected to a heating gas source and a downstream end opening into the lower part of the shell 2 near the bottom of the shell 2 and oriented towards the bottom.
[0020] Preferably, the downstream end of the vaporization line 7 opens at a distance from the bottom of the envelope 2 greater than zero millimeters and preferably between 0.1mm and three times the diameter of the vaporization line 7 entering the envelope and for example between 0.2mm and two times the diameter of this line 7. Typically this maximum distance of the outlet of the vaporization line 7 from the bottom is between 0.1mm and 10mm, for example between 0.2mm and 6mm.
[0021] The vaporization gas can thus be projected onto the bottom of the envelope 2 during its injection.
[0022] The vaporization gas preferably has a temperature higher than that of the vaporization temperature of the liquefied gas to be vaporized.
[0023] As illustrated, the downstream end of the vaporization line 7 can be fitted with a strainer 5 that subdivides the gas flow into several distinct jets. This allows the incoming flow in the jacket 2 to be divided into a maximum number of gas bubbles, thereby increasing the exchange surface area between the liquid and the gas. This reduces the amount of vaporization gas required to vaporize the volume of liquid.
[0024] The vaporization line 7 can also coincide with the liquid withdrawal line in normal operation.
[0025] As shown schematically, it is possible to heat the vaporization gas at the inlet in envelope 2 (or further upstream see at the source level) to reduce the amount of vaporization gas needed to vaporize the volume of liquefied gas.
[0026] This structure and operation can ensure that there is no more liquid at the end of the operation.
[0027] This operation can for example be stopped when the temperature of the bottom of the tank (for example measured) is higher than the liquefaction temperature of the gas to be vaporized (pressure-dependent temperature).
[0028] This allows a reservoir to be completely vaporized with a relatively faster vaporization time.
[0029] The solution also makes it possible to optimize the amount of vaporization gas used.
[0030] This is particularly advantageous in an installation which requires rapid vaporization, especially if the tank does not have a liquid outlet at the bottom.
[0031] The invention applies to any type of liquefied gas, for example cryogenic and in particular, hydrogen. Other liquefied gases may be considered (CO, ...).
[0032] The vaporization gas can be any suitable component or mixture, including: nitrogen, gas identical to that to be vaporized, dry air (if the gas to be vaporized is not flammable).
Claims
Demands
1. A method for vaporizing liquefied gas contained in a liquefied gas tank, in particular hydrogen, comprising a sealed casing (2) delimiting a storage volume for liquefied gas between a lower end and an upper end, a thermal insulation system (3) disposed around the casing (2) and a set of fluid transfer line(s) opening into the casing (2), the set of transfer line(s) comprising a vaporization line (7) having an upstream end intended to be connected to a source of heating gas and a downstream end opening into the lower part of the casing (2) near the bottom of the casing (2) and oriented towards the bottom, the method comprising a step of injecting a heating gas into the casing (2) via the vaporization line (7), the heating gas having a temperature higher than the liquefaction temperature of the liquefied gas,characterized in that the injection step is maintained until complete vaporization of the liquefied gas contained in the casing (2), and / or until the temperature of the bottom of the casing (2) is higher than the liquefaction temperature of the liquefied gas.
2. A process according to claim 1, characterized in that the liquefied gas is one of: hydrogen, CO, any toxic or flammable gas, and in that the vaporization gas comprises at least one of: nitrogen, a gas identical to that to be vaporized, dry air
3. The method according to claim 1, characterized in that the downstream end of the vaporization line (7) opens at a distance from the bottom of the casing (2) greater than zero millimeters and less than three times the diameter of the vaporization line (4).
4. A method according to any one of claims 1 to 3, characterized in that the downstream end of the vaporization line (7) is provided with a screen (5) subdividing the gas flow into several distinct jets.
5. A method according to any one of claims 1 to 4, characterized in that the vaporization conduit (7) passes through the envelope (2) via the bottom of the envelope (2) from bottom to top and is bent in the envelope towards the bottom.
6. A method according to any one of claims 1 to 5, characterized in that it comprises a heating element (6) for the gas stream transported by the vaporization line (7).