Patent ID: 12222072

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The cryogenic tank1for storing liquefied fluid, which is illustrated by way of example, comprises an inner shell2delimiting a storage volume for liquefied fluid and an outer shell3arranged in a spaced manner around the inner shell2.

The space between the inner2and outer3shells comprises a thermal insulation4, for example a thermal insulant of the multilayer type (“MU”). This space is preferably held under vacuum.

The inner2and outer3shells extend in a longitudinal direction A between two longitudinal ends.

In the use configuration of the tank1, this longitudinal direction A is preferably horizontal (horizontal tank).

The tank1is preferably of cylindrical type (cylindrical portion dosed at each end by a curved wall in the form of a dome).

The tank1comprises a structure for holding (or supporting) the inner shell2in the outer shell3. This holding structure is composed of (and preferably formed by) two connections respectively situated at the two longitudinal ends. The holding structure comprises a first mechanical connection5between a first longitudinal end of the inner shell2and a first longitudinal end of the outer shell3, and a second mechanical connection6between the second longitudinal end of the inner shell2and the second longitudinal end of the outer shell3.

The first mechanical connection comprises a first support wall5of general truncated cone shape whose larger-diameter end is rigidly connected to the outer shell3and whose smaller-diameter end is connected to the inner shell2.

The first support wall5is preferably inclined by an angle of between zero degrees (preferably greater than zero) and 30 degrees and preferably five degrees with respect to the longitudinal direction A.

The second mechanical connection comprises a second support wall6of general truncated cone shape whose larger-diameter end is rigidly connected to the outer shell3and whose smaller-diameter end is connected to the inner shell2.

The second support wall6is preferably inclined by an angle of between 60 degrees and 89 degrees and preferably 85 degrees with respect to the longitudinal direction.

As illustrated, the first support wall5is preferably oriented in such a way that the truncated cone converges in the direction of the second longitudinal end (towards the left in the schematic representation).

The second support wall6is preferably oriented in such a way that the truncated cone converges in the direction of the second longitudinal end.

Preferably, the second support wall6constitutes a connection between the two shells2,3that is more deformable (relatively more flexible connection) than the first support wall5(relatively more rigid connection). That is to say that the second support wall6is configured so that, during a temperature differential between the two shells2,3generating a relative retraction or expansion of the shells2,3, it allows a relative longitudinal movement between the two shells2,3at the second end that is greater than the relative longitudinal movement allowed by the first support wall5at the first end.

These relative degrees of flexibility or rigidity can be chosen by adapting the relative orientations (inclinations) of the walls5,6and/or their dimension (in particular thickness) and/or their materials.

Thus, the inner shell2can be supported in the outer shell3by two conical walls5,6, one of which is relatively more deformable and configured in particular to deform during the relative contraction of the chilled inner shell2. This deformation is configured to make it possible to absorb the variations in the relative dimensions of the two shells2,3without impairing the holding of the inner shell in the outer shell3and without affecting the thermal insulation.

In particular, this architecture allows a deformation of the second support wall6that is close to the relative longitudinal contraction of the inner shell2(and that allows this contraction of the inner shell2).

The second support wall6may be formed, for example, of steel, for example a stainless steel of the 304 or 316 type.

When filling the inner shell2with cryogenic liquid, the thermal gradient (from the outside ambient temperature to the temperature of the cryogenic liquid on the inside: for example between −269° C. and −180° C.) that will be experienced by this second wall6will make it possible to accompany the thermal contraction of the inner shell2at the second end, whereas the first end (at the first connection5, considered as a fixed point) will undergo a zero or smaller deformation. During its contraction, the inner shell2(at least one end connected to the inner shell2) will move longitudinally relatively towards the first (relatively fixed) end.

Note that the term “flexible” used above does not necessarily mean that the second wall6is intrinsically “flexible”. Specifically, the conical geometry is by nature relatively rigid in comparison to a flat metal sheet. On the other hand, this second support wall6is configured to deform (longitudinal movement) in response to the changes of temperature while allowing resistance to radial forces. In particular, the second support wall6is thus able and configured to maintain sufficient rigidity in the radial (transverse) directions in order to take up the forces.

This first connection5is therefore a fixed point with respect to the thermodynamics. This first connection is preferably configured to:

transmit the radial (vertical and lateral) forces (for example between the two shells2,3),

transmit the longitudinal forces (acceleration of2gfor example) (for example between the two shells2,3).

During its deformation, the second wall6can, for example, be inclined so as to come slightly closer to the longitudinal direction A.

At least the first support wall5can be formed of one or more assembled parts, for example two welded rigid half-cones (for example made of stainless steel, such as of the type 304 or 316). The structure in the form of two half-cones can in particular make it possible to centre the inner shell2in the outer shell3during mounting.

As illustrated, the connection between the first support wall5and the outer shell3can be fastened (welded) very close to the end wall (end) of the outer shell3, preferably at the cylindrical parts of the shells2,3, for example in the vicinity of inter-wall pipework (not shown for the sake of simplification).

Likewise, the second support wall6can be fastened (welded) very close to the end wall (end) of the inner shell2.

Note that the structure for holding the inner shell2in the outer shell3is preferably formed by the first support wall5and second support wall6. That is to say that, preferably, there is no other structure for supporting the inner shell2. However, one or more other additional connections (tie rod(s) for example) can be envisaged.

Moreover, the tank may comprise connection elements between the shells2,3, in particular for the passage or guidance of pipework between the shells2,3(but these elements do not necessarily ensure a function of supporting that is comparable to that of the two walls5,6).

Note that the shape of the support wall(s) is designated as “general truncated cone shape”. This means that the wall in question can in fact be in the form of a truncated cone. However, any other similar shape can be envisaged, in particular a curved shape similar to a cone.