NO20220733A1

NO20220733A1 - Insulation system for tanks feasible for storage of liquid hydrogen

Info

Publication number: NO20220733A1
Application number: NO20220733A
Authority: NO
Inventors: Pål G Bergan
Original assignee: Lattice Int As
Priority date: 2022-06-28
Filing date: 2022-06-28
Publication date: 2023-12-29
Also published as: KR20240002716A

Description

【Invention Title 】

Insulation system for tanks feasible for storage of liquid hydrogen.

【Technical Field 】

The present invention relates to an insulation system for a liquid hydrogen storage tank. More specifically, the invention provides an insulation system including safety barriers and leak detection systems for a liquid hydrogen tank that can be either a membrane tank or an independent tank.

【Background Art 】

It is challenging to store and transport liquid hydrogen (LH2) whose temperature is around -250 °C because oxygen and nitrogen, the major components of air, liquefy and solidify above this temperature. This explains why all the LH2 tanks so far have been equipped with a vacuum insulation layer around the primary barrier that is in direct contact with LH2. Fig. 1 shows concept of a LH2 tank with conventional vacuum insulation layer.

The demand of hydrogen is increasing due to its role and further potential as energy carrier for renewable energy. That is, for example that solar and/or wind energy and/or hydropower is used as energy source for water electrolysis to produce hydrogen, and/or that carbon captured fossil- or bio-based energy produce hydrogen, which hydrogen should be liquefied and stored in LH2 tanks for long-term use and long-distance transport. The need for large LH2 tanks can be expected to increase along with the increasing demand for hydrogen.

As the size of an LH2 tank increases, its vacuum insulation become challenging for several reasons. One reason is that the risk of leak increases with the tank size. The larger the tank is, the larger the surface area of the vacuum insulation layer, and the more the potential leak sources emerge on the surface. One small leak through the surface can damage the performance of the whole vacuum insulation system. A second reason is related to the difficulty with the detection of the leak. Even though the failure of the vacuum insulation can be identified by its pressure increase, it is not easy to locate the position of the leak. A third reason is the challenge of maintenance. Even when the leak is located, it can be difficult to repair the leak due to the complex insulation structure. Another reason is the weight of the vacuum jacket structure. Unlike the LH2 tank itself which withstands the increasing pressure load, the vacuum jacket should withstand both bending load and structural stability due to the external pressure load. Hence, in case of an independent pressure tank with vacuum insulation, the weight of the surrounding vacuum jacket can be comparable to that of the LH2 tank. All these reasons in combination contribute to increased cost of a vacuum insulation system for large LH2 tanks.

Theoretically, non-vacuum insulation can be equipped to LH2 tanks by filling the insulation layer with non-condensing gases which do not liquefy at the LH2 storage temperature. However, the choice of non-condensing gases is limited to only helium or hydrogen. Helium is very rare and expensive, so it will normally not make economic sense to use helium for large LH2 tanks. Hydrogen is thus the only practical choice. However, to use hydrogen as the filling gas for non-vacuum insulation also brings with it several challenges. A primary problem is the flammability of hydrogen A leak of air through the insulation layer can lead to devastating fire and explosion. Another challenge is that both the filling gas and the stored gas are hydrogen. It is thus difficult to distinguish the filling gas from the stored gas when they are mixed due to leak.

Following an approach of modifying conventional LNG (Liquefied Natural Gas) non-vacuum, membrane tank technology, to an LH2 membrane tank is faced with a several challenges. A conventional LNG membrane tank contains two barriers, the primary and the secondary barrier, with two insulation layers, the inner and the outer insulation layer. Since this membrane structure cannot carry the loads from the cargo by itself, the membrane structure needs to be fully supported by a surrounding structure, which typically is the hull structure in case of a LNG ship. Since the membrane barriers are made of thin plates, there exists the possibility that they can be damaged, resulting in leakage. For this reason, LNG membrane tanks must satisfy the requirement of double protection layers with a secondary barrier in addition to the primary barrier with two independent gas detection systems.

Fig. 2 shows leak detection system for conventional LNG membrane tank. In order to detect leak through the barriers, an inert gas, typically nitrogen, is filled in the inner and outer insulation layers, whose outlets are connected to methane gas detection systems. Normally, the pressure within the insulation layers is kept at atmospheric pressure or slightly above atmospheric pressure. Depending on the temperature of the primary barrier, for example during cooldown and warm-up operation, the temperature of the filling nitrogen gas changes, and so does its density, equivalently its pressure. When the pressure of the filling gas nitrogen falls below the set pressure, nitrogen is supplied to the insulation layer. Reversely, when it rises above the set pressure, nitrogen is vented from the insulation layer. In case of a leak the pressure of the filling nitrogen and the leaked methane will increase, resulting in being vented to the methane gas detection system which can detect methane in the vented gas.

Fig. 3 shows LH2 membrane tank with secondary barrier, which is similar to conventional membrane LNG tanks. Assuming that the LNG membrane tank technology is implemented for LH2 membrane tank, the inner insulation layer should be filled with hydrogen at all times. When there is a leak through the primary barrier, the cargo hydrogen leaks into the inner insulation layer. However, the hydrogen detection system 1 cannot distinguish the leaked hydrogen from the supplied hydrogen at the inlet of the insulation layer. It means that the hydrogen detection system 1 does not function, and the insulation system cannot satisfy the requirement of the double protection layers.

【Disclosure 】

【Summary of the invention 】

An embodiment of the present invention is directed to providing an insulation system for a liquid hydrogen storage tank, which may include a nonvacuum insulation layer, implementing an easily made insulation layer, facilitating scale-up of storage volume, and reducing the insulation weight compared with the conventional vacuum insulation, and which may accurately detect whether the leak occurs by measuring the para hydrogen concentration, and/or the ortho hydrogen concentration and/or increased pressure and/or decreased temperature and/or increased venting flow rate or frequency and/or the combination of two or more of said parameters in any combination is not compliant with non-leakage.

More specifically, the invention provides an insulation system for a liquid hydrogen storage tank, the tank comprising a primary barrier 111 for containing hydrogen liquid inside,

the insulation system comprising:

an inner insulation layer 121 that surrounds the primary barrier 111;

a secondary barrier 112 that is fluid tight surrounding the inner insulation layer 121. The invention is distinguished in that the insulation system further comprises:

a hydrogen supplying connection 131 that supplies hydrogen gas to the inner insulation layer 121; and

a hydrogen venting connection 141 that vents hydrogen gas from the inner insulation layer 121 to exterior;

and preferably also a hydrogen leakage detection system.

Preferably, the hydrogen leakage detection system comprises an isomer detection system 151 that detects para hydrogen (i.e. para H2) and/or ortho hydrogen. Preferably, para hydrogen, and/or ortho hydrogen, is detected in hydrogen vented from the hydrogen venting connection 141.

Preferably, the hydrogen leakage detection system comprises instrumentation to detect pressure or overpressure in the insulation, and/or instrumentation to detect hydrogen venting flow rate or -frequency, and preferably also hydrogen supply flow rate or -frequency for comparison, and/or instrumentation to measure temperature in the insulation, preferably at numerous positions, and/or in vented hydrogen.

Preferably, the hydrogen leakage detection system comprises an algorithm and/or a look-up table to determine whether the combination of para hydrogen, ortho hydrogen, pressure, temperature and/or flow rate- or frequency of hydrogen venting complies with non-leakage or not. Preferably, the hydrogen leakage detection system further comprises coupling to a control room or operator for displaying information on the situation and alarming if a set limit of noncompliance, indicating leakage, is crossed.

【Technical Solution 】

In one general aspect, an insulation system 100 for a liquid hydrogen storage tank includes: a primary barrier 111 that contains liquid hydrogen; an inner insulation layer 121 that surrounds the primary barrier 111; a secondary barrier 112 that is fluid tight surrounding the inner insulation layer 121; a hydrogen supplying connection 131 that supplies hydrogen to the inner insulation layer 121; a hydrogen venting connection 141 that vents hydrogen from the inner insulation layer 121 to exterior; and preferably a hydrogen leakage detection system, preferably comprising a hydrogen isomer detection system 151 that detects para hydrogen (i.e., para H2) vented from the hydrogen venting connection 141.

One interesting characteristics of hydrogen is that a hydrogen molecule exists as one of two feasible isomers. Depending on the two proton spins, molecular hydrogen occurs in two isomeric forms: ortho hydrogen and para hydrogen. The latter has lower energy state. Their equilibrium ratio varies with temperature. The ratio of ortho hydrogen to para hydrogen is around 75 : 25 at room temperature and close to 0 : 100 at the liquid hydrogen temperature. That is, the LH2 in equilibrium is almost 100% para hydrogen. Fig. 4 shows fraction of ortho hydrogen in equilibrium with temperature.

Since their energy states are different from each other, the transition between them accompanies a significant amount of heat of transition, and it takes several hundred hours for them to achieve the thermal equilibrium ratio when temperature is changed. For example, when LH2 is exposed to high temperature after leak, it vaporizes to initially form a vapor of 100% para hydrogen, which slowly converts into ortho hydrogen with time. Fig. 5 shows fraction of hydrogen isomers with time in natural conversion process.

Several measurement methods are available to detect the hydrogen state ratio including the Raman spectrometer and the measurement of the adiabatic heat of conversion between the isomers. It implies that leakage of LH2 can be detected if the leaked vapor is quickly analyzed by these measurement methods

Here, the insulation system 100 may detect whether liquid hydrogen leaks in the primary barrier 111 by using whether a higher concentration of para hydrogen than the equilibrium condition is detected by the hydrogen isomer detection system 151, based on a principle that when leaking and exposed to a high temperature, liquid hydrogen vaporizes to initially form a para-hydrogen vapor mostly, and to be converted to ortho hydrogen (i.e, ortho H2) over time due to a property of ortho H2 in which a fraction thereof in equilibrium depends on a temperature.

In addition, the insulation system 100 may detect whether liquid hydrogen leaks in the primary barrier 111 by using whether a higher concentration ofpara hydrogen than the equilibrium condition is detected by the hydrogen isomer detection system 151 as well as whether a pressure of the inner insulation layer 121 is increased suddenly.

In addition, the inner insulation layer 121 may be made of a porous insulation material containing gas, or may be a gas layer.

In addition, the insulation system 100 may be applied to an independent tank standing on its foundation, or may be applied to a membrane tank supported by its surrounding structure and the insulation layer.

In addition, when applied to the independent tank, the insulation system 100 may further include an inner support 161 interposed between the primary barrier 111 and the secondary barrier 112 to support the primary barrier and maintain the two barriers to be spaced apart from each other; and an outer support 162 interposed between the secondary barrier 112 and the foundation to support the secondary barrier and maintain the barrier and the foundation to be spaced apart from each other.

In addition, the insulation system 100 may further include a surrounding structure 165 positioned on an outermost portion to isolate an inner space from an external environment.

In addition, the insulation system 100 may further include a void space supplying connection 135 supplying inert gas to the void space 125 in the surrounding structure 165; and a void space venting connection 145 venting gas from the void space 125.

In addition, the insulation system 100 may further include: an outer insulation layer 122 positioned on an outer surface of the secondary barrier 112 or an inner surface of the surrounding structure 165; an outer supplying connection 132 supplying inert gas to the outer insulation layer 122; and an outer venting connection 142 venting gas from the outer insulation layer 122.

In addition, the outer insulation layer 122 may be made of a porous insulation material containing gas, or may be a gas layer.

In addition, the insulation system 100 may further include a tertiary barrier 113 that surrounds the outer insulation layer 122.

In addition, the tertiary barrier 113 may surround the outer surface of the outer insulation layer 122 when the outer insulation layer 122 is positioned on the outer surface of the secondary barrier 112, and the tertiary barrier 113 may surround an inner surface of the outer insulation layer 122 when the outer insulation layer 122 is positioned on the inner surface of the surrounding structure 165.

In addition, when the outer insulation layer 122 is positioned on the inner surface of the surrounding structure 165 and the tertiary barrier 113 surrounds the inner surface of the outer insulation layer 122, the insulation system 100 may further include a middle insulation layer 123 which is a space between the secondary barrier 112 and the tertiary barrier 113; a middle supplying connection 133 supplying inert gas to the middle insulation layer 123; and a middle venting connection 143 venting gas from the middle insulation layer 123.

In addition, the insulation system 100 may further include at least one hydrogen detection system 152 that is positioned in the void space 125 or detects hydrogen from gas vented from the insulation system 100 through an exhaust line other than the hydrogen venting connection 141.

In addition, the insulation system 100 may detect whether liquid hydrogen leaks through a barrier other than the primary barrier 111 by using whether hydrogen is detected by the hydrogen detection system 152.

【Advantageous Effects 】

As set forth above, according to the present invention, the liquid hydrogen storage tank may include the non-vacuum insulation layer, easily detecting the leak of liquid hydrogen, and reducing the weight of the overall system by reducing unnecessary structures.

In particular, according to the present invention, it is possible to easily detect whether liquid hydrogen leaks by using whether para hydrogen is detected, based on the principle that when leaking and exposed to the high temperature, liquid hydrogen vaporizes to initially form the para-hydrogen vapor mostly, and to be converted to ortho hydrogen (i.e. ortho H2) over time due to a property of ortho H2 in which a fraction thereof in equilibrium depends on the surrounding temperature. It is also possible to detect hydrogen in several spaces separated from each other, thereby accurately determining where the leak occurs among the barriers each defining the respective spaces.

【Description of Drawings 】

Fig. 1 shows concept of LH2 tank with conventional vacuum insulation

layer.

Fig. 2 shows leak detection system for conventional LNG membrane

tank.

Fig. 3 shows LH2 membrane tank with secondary barrier(similar to LNG tank).

Fig. 4 shows fraction of ortho hydrogen in equilibrium with temperature. Fig. 5 shows fraction of hydrogen isomers with time in natural conversion process.

Fig. 6 shows an insulation system for an LH2 tank with H2 isomer detection system.

Fig. 7 shows an insulation system for an independent LH2 tank with H2 isomer detection system.

Fig. 8 shows an insulation system for an independent LH2 tank in a surrounding structure.

Fig. 9 shows an insulation system for an independent LH2 tank with a secondary and tertiary barrier in a surrounding structure.

Fig. 10 shows an insulation system for an independent LH2 tank with a secondary and tertiary barrier and with outer insulation layer on a surrounding structure.

Fig. 11 shows an insulation system for an independent LH2 tank with a secondary barrier and with outer insulation layer on a surrounding structure.

Fig. 12 shows an insulation system for a membrane LH2 tank with a secondary barrier.

Fig. 13 shows an insulation system for a membrane LH2 tank with a secondary and tertiary barrier.

【Mode for Invention 】

Motivation and Summary of invention are below:

- LH2 tanks usually need vacuum insulation to avoid condensation and solidification of surrounding air. However, vacuum insulation can be heavy and difficult to fabricate and maintain.

- This invention is to provide non-vacuum insulation for LH2 tanks, which can be membrane tanks or independent tanks.

- For this, the inner insulation layer is filled with hydrogen and is preferably connected to the hydrogen isomer hydrogen detection system which can detect the para hydrogen leaking from the LH2 tanks. Additional insulation layers can be installed, filled with nitrogen, and connected to the hydrogen gas detection system, which can detect leaked hydrogen through additional barriers.

Fig. 6 shows an insulation system for an LH2 tank with the H2 isomer detection system. The invention provides an insulation system comprising the components in direction from the stored LH2:

- a primary barrier 111 that contains LH2

- an inner insulation layer 121 that surrounds the primary barrier 111

- a secondary barrier 112 that is fluid tight surrounding the inner insulation layer 121

- a hydrogen supplying connection 131 that supplies hydrogen to the inner insulation layer 121

- a hydrogen venting connection 141 that vents hydrogen from the inner insulation layer 121 to exterior

- a hydrogen isomer detection system 151 that detects para hydrogen vented from the hydrogen venting connection 141

The pressure of the inner insulation layer 121 is kept at the set pressure which is close to atmospheric pressure as follows. Originally, the inner insulation layer 121 is filled with gas hydrogen which is rich in ortho hydrogen. When the primary barrier 111 is cooled down for any reason, for example, during cooldown operation or LH2 loading operation, the temperature of the inner insulation layer 121 drops, and so does the pressure of the inner insulation layer 121. Then, the gas hydrogen is supplied through the hydrogen supplying connection 131 to make the pressure of the inner insulation layer 121 close to atmospheric pressure.

To the contrary, when the primary barrier 111 is warmed up for any reason, for example, during warm-up operation or LH2 unloading operation, the temperature of the inner insulation layer 121 rises, and so does the pressure of the inner insulation layer 121. Then, the gas hydrogen is vented through the hydrogen venting connection 141 to make the pressure of the inner insulation layer 121 close to atmospheric pressure. In this case, the hydrogen close to the primary barrier 111 around the LH2 temperature slowly converts to para hydrogen while the hydrogen close to the secondary barrier 112 around the atmospheric temperature stays as ortho hydrogen. Consequently, the vented hydrogen detected by the hydrogen isomer detection system 151 has a higher concentration of para hydrogen than the gas hydrogen fed through the hydrogen supplying connection 131.

Note that the filling hydrogen does not condense since its pressure at safe operating conditions is lower than that of the cargo LH2. The condensation temperature of hydrogen, like most other substances, increases with its vapor pressure. The pressure of the filling hydrogen is close to atmospheric pressure. So, its condensation temperature is the normal boiling point of hydrogen, precisely -253°C at atmospheric pressure. The vapor pressure of the LH2 cargo is always higher than the atmospheric pressure, typically 0.1 bar or higher. That is, the temperature of the LH2 cargo is higher than the normal boiling point. If it is assumed that there should be no flow within the LH2 phase, the bottom of the LH2 should have a larger pressure than the vapor pressure of the LH2 cargo by the static hydraulic load, which is the product of the gravitational acceleration, density, and the depth. That is, the bottom of the LH2 phase should have a higher temperature than the surface of the LH2 phase. However, there is a natural convection within the LH2 phase due to the heat ingress through its boundary. Nevertheless, all boundary of the LH2 phase has the higher temperature than the normal boiling point of hydrogen, and the filling hydrogen does not condense.

The leak in the primary barrier 111 is detected as follows. Where there is a leak in the primary barrier 111, LH2 leaks into the inner insulation layer 121 where LH2 vaporizes to form a vapor phase that is rich in para hydrogen. Simultaneously, the vaporized hydrogen increases the pressure of the inner insulation layer 121, requiring venting of the hydrogen from the inner insulation layer 121. In this case, the vented hydrogen detected by the hydrogen isomer detection system 151 shows a sudden increase in para hydrogen than the gas hydrogen fed through the hydrogen supplying connection 131. That is, the leak in the primary barrier 111 is detected by the sudden increase in the pressure of the inner insulation layer 121 and the sudden increase in the para hydrogen detected by the hydrogen isomer detection system 151.

There can be a number of variations of the invention that improve safety and insulation performance by adding additional detection systems and insulation layers.

Fig. 7 shows an insulation system for an independent LH2 tank with H2 isomer detection system. As described in Fig. 7, the invention can be applied to an independent LH2 tank, which stands on a foundation. In more detail, as in an embodiment of Fig. 6, the insulation system in an embodiment of Fig. 7 may further include an internal support 161 interposed between the primary barrier 111 and the secondary barrier 112 to support the primary barrier and maintain the two barriers to be spaced apart from each other, and an outer support 162 interposed between the secondary barrier 112 and the foundation (e.g., ground) to support the secondary barrier and maintain the barrier and the foundation to be spaced apart from each other.

Fig. 8 shows an insulation system for an independent LH2 tank in a surrounding structure. When the LH2 tank is installed within a surrounding structure 165, for example, the LH2 cargo tank for a ship, a void space 125 is formed between the secondary barrier 112 and the surrounding structure 165. Air or inert gas, typically nitrogen, is filled in this space. In order to detect the leak of the secondary barrier 112, a hydrogen detection system 152 is installed on the venting line or in the void space 125. In more detail, as in an embodiment of Fig. 7, the insulation system in an embodiment of Fig. 8 may include a surrounding structure 165 positioned on an outermost portion to isolate an inner space from an external environment. In order to supply or vent gas to or from the void space 125 in the surrounding structure 165, the insulation system may further include a void space supplying connection 135 supplying inert gas to the void space 125 and a void space venting connection 145 venting gas from the void space 125. Here, the hydrogen detection system 152 may be positioned in the void space 125 or the void space venting connection 145.

Fig. 9 shows an insulation system for an independent LH2 tank with a secondary and tertiary barrier in a surrounding structure. As described in Fig. 9, an additional insulation layer with an additional barrier and an additional detection system can be applied. For example, the outer insulation layer 122 covered by the tertiary barrier 113 is formed between the secondary barrier 112 and the void space 125. In more detail, as in an embodiment of Fig. 8, the insulation system in an embodiment of Fig. 9 may further include the outer insulation layer 122 positioned on an outer surface of the secondary barrier 112 and the tertiary barrier 113 that surrounds the outer insulation layer 122. In order to supply or vent gas to or from the outer insulation layer 122, the insulation system may further include an outer supplying connection 132 supplying inert gas to the outer insulation layer 122, and an outer venting connection 142 venting gas from the outer insulation layer 122. Here, the hydrogen detection system 152 may be positioned in the void space 125, the void space venting connection 145 or the outer venting connection 142.

In detail, the inner insulation layer 121 described above may be made of a porous insulation material containing gas, and thus be maintained with no barrier. The same may be applied to the outer insulation layer 122. However, the present invention is not limited thereto, and the inner insulation layer 121 and/or the outer insulation layer 122 may be a gas layer in the case of the membrane tank or the like rather than the independent tank.

Fig. 10 shows an insulation system for an independent LH2 tank with a secondary and tertiary barrier and with outer insulation layer on a surrounding structure. As described in Fig. 10, the outer insulation layer can be formed on the surrounding structure. That is, even though an embodiment of Fig. 10 is similar to an embodiment of Fig. 9, an embodiment of Fig. 9 shows the outer insulation layer 122 positioned on the outer surface of the secondary barrier 112, whereas an embodiment of Fig. 10 shows the outer insulation layer 122 positioned on an inner surface of the surrounding structure 165, i.e. slightly different position of the outer insulation layer 122. Therefore, as in an embodiment of Fig. 9, the insulation system in an embodiment of Fig. 10 may include the outer supplying connection 132, the outer venting connection 142 or the like.

Fig. 11 shows an insulation system for an independent LH2 tank with a secondary barrier and with outer insulation layer on a surrounding structure. As described in Fig. 11, the secondary barrier can be moved from the surface of the inner insulation layer and formed on the surface of the outer insulation layer. That is, the insulation system in an embodiment of Fig. 11 may be the same as the insulation system in an embodiment of Fig. 11 from which the barrier around the inner insulation layer 121 is removed. The inner insulation layer 121 may be made of the porous insulation material containing gas or the like, and thus be maintained with no barrier.

Fig. 12 shows an insulation system for a membrane LH2 tank with a secondary barrier. As described in Fig. 12, the invention can be applied to membrane tanks which should be supported by insulation layers and ultimately by the surrounding structure. A structure of the insulation system in an embodiment of Fig. 12 may be considered equivalent to that in an embodiment of Fig. 8.

Fig. 13 shows an insulation system for a membrane LH2 tank with a secondary and tertiary barrier. As described in Fig. 13, the safety and insulation performance can be improved by an additional insulation layer with an additional barrier. In more detail, as in an embodiment of Fig. 12, the insulation system in an embodiment of Fig. 13 may further include the tertiary barrier 113 positioned between the secondary barrier 112 and the void space 125. Here, inert gas (e.g., nitrogen) may be filled in a space between the secondary barrier 112 and the tertiary barrier 113 to form the middle insulation layer 123 which is the gas layer. Here, in order to supply or vent gas to or from the middle insulation layer 123, the insulation system may further include a middle supplying connection 133 supplying inert gas to the middle insulation layer 123, and a middle venting connection 143 venting gas from the middle insulation layer 123. A structure of the insulation system in an embodiment of Fig. 13 may be considered similar to that in an embodiment of Fig. 10 or 11.

【explanation of marks 】

100 : liquid hydrogen tank insulation system

111 : primary barrier

112 : secondary barrier

113 : tertiary barrier

121 : inner insulation layer

122 : outer insulation layer

123 : middle insulation layer

125 : void space

131 : hydrogen supplying connection

132 : outer supplying connection

133 : middle supplying connection

135 : void space supplying connection

141 : hydrogen venting connection 142 : outer venting connection

143 : middle venting connection

145 : void space venting connection 151 : hydrogen isomer detection system 152 : hydrogen detection system

161 : inner support

162 : outer support

165 : surrounding structure

Claims

[CLAIMS]

[Claim 1]

An insulation system (100) for a liquid hydrogen storage tank, the tank comprising a primary barrier (111) for containing hydrogen liquid inside, the insulation system comprising:

an inner insulation layer (121) that surrounds the primary barrier (111); a secondary barrier (112) that is fluid tight surrounding the inner insulation layer (121);

c h a r a c t e r i s e d i n that the insulation system further comprises: a hydrogen supplying connection (131) that supplies hydrogen to the inner insulation layer (121); and

a hydrogen venting connection (141) that vents hydrogen from the inner insulation layer (121) to exterior;

and preferably further comprising a hydrogen leakage detection system.
[Claim 2]

The insulation system of claim 1, comprising a hydrogen leakage detection system comprising an isomer detection system (151) that detects para hydrogen (i.e. para H2) and/or ortho hydrogen.
[Claim 3]

The insulation system of claim 2, wherein para hydrogen, and/or ortho hydrogen, is detected in hydrogen vented from the hydrogen venting connection (141).
[Claim 4]

The insulation system of any one of claim 1 - 3, wherein the hydrogen leakage detection system comprises instrumentation to detect pressure or overpressure in the insulation.
[Claim 5]

The insulation system of any one of claim 1 - 4, wherein the hydrogen leakage detection system comprises instrumentation to detect hydrogen venting flow rate or -frequency, and preferably also hydrogen supply flow rate or -frequency.
[Claim 6]

The insulation system of any one of claim 1 - 5, wherein the hydrogen leakage detection system comprises instrumentation to measure temperature in the insulation and/or in vented hydrogen.
[Claim 7]

The insulation system of any one of claim 1 - 6, wherein the hydrogen leakage detection system comprises an algorithm and/or a look-up table to determine whether the combination of para hydrogen, ortho hydrogen, pressure, temperature and/or flow rate- or frequency of hydrogen venting complies with non-leakage or not, preferably the hydrogen leakage detection system further comprises coupling to a control room or operator for displaying information on the situation and alarming if a set limit of non-compliance, such as 1%, 3% or 5% or more outside a measured parameter equilibrium value, indicating leakage, is crossed.
[Claim 8]

The insulation system of claim 1, wherein the insulation system 100 detects whether liquid hydrogen leaks in the primary barrier 111 by using whether a higher concentration of para hydrogen than the equilibrium condition is detected by the hydrogen isomer detection system 151,

based on a principle that when leaking and exposed to a high temperature, liquid hydrogen vaporizes to initially form a para-hydrogen vapor mostly, and to be converted to ortho hydrogen (i.e., ortho H2) over time due to a property of ortho H2 in which a fraction thereof in equilibrium depends on a temperature.
[Claim 9]

The insulation system of claim 8, wherein the insulation system 100 detects whether liquid hydrogen leaks in the primary barrier 111 by establishing whether the concentration of para hydrogen is higher than the equilibrium condition detected by the hydrogen isomer detection system 151 as well as whether a pressure of the inner insulation layer 121 is increased.
[Claim 10]

The insulation system of claim 1, wherein the inner insulation layer 121 is made of a porous insulation material containing gas, or is a gas layer.
[Claim 11]

The insulation system of claim 1, wherein the insulation system 100 is applied to an independent tank standing on its foundation, or applied to a membrane tank supported by its surrounding structure and the insulation layer.
[Claim 12]

The insulation system of claim 11, when applied to the independent tank, further comprising:

an inner support 161 interposed between the primary barrier 111 and the secondary barrier 112 to support the primary barrier and maintain the two barriers to be spaced apart from each other; and

an outer support 162 interposed between the secondary barrier 112 and the foundation to support the secondary barrier and maintain the barrier and the foundation to be spaced apart from each other.
[Claim 13]

The insulation system of claim 1, further comprising a surrounding structure 165 positioned on an outermost portion to isolate an inner space from an external environment.
[Claim 14]

The insulation system of claim 13, further comprising:

a void space supplying connection 135 supplying inert gas to the void space 125 in the surrounding structure 165; and

a void space venting connection 145 venting gas from the void space 125.
[Claim 15]

The insulation system of claim 13, further comprising:

an outer insulation layer 122 positioned on an outer surface of the secondary barrier 112 or an inner surface of the surrounding structure 165;

an outer supplying connection 132 supplying inert gas to the outer insulation layer 122; and

an outer venting connection 142 venting gas from the outer insulation layer 122.
[Claim 16]

The insulation system of claim 15, wherein the outer insulation layer 122 is made of a porous insulation material containing gas, or is a gas layer.
[Claim 17]

The insulation system of claim 15, further comprising a tertiary barrier 113 that surrounds the outer insulation layer 122.
[Claim 18]

The insulation system of claim 17, wherein the tertiary barrier 113 surrounds the outer surface of the outer insulation layer 122 when the outer insulation layer 122 is positioned on the outer surface of the secondary barrier 112, and

the tertiary barrier 113 surrounds an inner surface of the outer insulation layer 122 when the outer insulation layer 122 is positioned on the inner surface of the surrounding structure 165.
[Claim 19]

The insulation system of claim 18, when the outer insulation layer 122 is positioned on the inner surface of the surrounding structure 165, and the tertiary barrier 113 surrounds the inner surface of the outer insulation layer 122, further comprising:

a middle insulation layer 123 which is a space between the secondary barrier 112 and the tertiary barrier 113;

a middle supplying connection 133 supplying inert gas to the middle insulation layer 123; and

a middle venting connection 143 venting gas from the middle insulation layer 123.
[Claim 20]

The insulation system of any one of claims 14, 15 and 19, further comprising at least one hydrogen detection system 152 that is positioned in the void space 125 or detects hydrogen from gas vented from the insulation system 100 through an exhaust line other than the hydrogen venting connection 141.
[Claim 21]

The insulation system of claim 20, wherein the insulation system 100 detects whether liquid hydrogen leaks in a barrier other than the primary barrier 111 by using whether hydrogen is detected by the hydrogen detection system 152.