THERMALLY INSULATED CONTAINER CONTAINING EQUIPMENT THAT FUNCTIONS AT TEMPERATURES BELOW 0 °C

Description

[0001] The present invention relates to a thermally insulated enclosure containing equipment intended to operate at a temperature below 0°C, or even at a cryogenic temperature, and adapted to carry out a separation process at a temperature below 0°C by distillation and / or washing.

[0002] Such enclosures are used to isolate a cryogenic distillation column. Typically, the enclosure is filled with perlite, but to improve thermal insulation, it is known to draw the perlite-filled enclosure under vacuum. Vacuum perlite is a classic, high-performance thermal insulator used in cryogenic storage or cold boxes for cryogenic gas separation equipment. The outer shell of the storage or cold box, essentially cylindrical or spherical in shape, is mechanically dimensioned to withstand vacuum under reverse pressure, which necessitates a thick, expensive, and heavy wall.

[0003] The enclosure's shape, free of edges and corners, is essential to improve resistance to external pressure. As noted in FR2695714 and CN103123202A, a vacuum-insulated distillation column is, by definition, housed in a cylindrical enclosure. A cylindrical enclosure typically has bottoms that are either hemispherical or hemispherical.

[0004] However, the parallelepiped shape generally used when thermal insulation is not under vacuum has a number of advantages, in particular, greater ease of keeping in place for transport and a better filling rate when a container is used for transport, or when the equipment is parallelepipeds, typically brazed aluminum plate heat exchangers.

[0005] When a parallelepiped-shaped enclosure is pulled into a vacuum, the walls forming the enclosure do not mechanically resist the vacuum with a wall of a small thickness.

[0006] Furthermore, when using powdered perlite, it has the disadvantage of settling during the vacuuming process. Expanded perlite, commonly used for thermal insulation of enclosures, has an irregular shape that can break when subjected to excessive pressure. According to prior art, an external cylindrical or spherical casing is sized to mechanically maintain a vacuum (i.e., withstand the atmospheric pressure of 1 bar applied to its outer surface): this requires a substantial wall thickness due to the reverse pressure, sometimes combined with the use of reinforcing rings. The enclosure is filled through an opening, then a vacuum is drawn, and the vacuum is broken by injecting perlite through the opening. Several cycles of "vacuum drawing - vacuum breaking with the addition of perlite" are repeated until the perlite is well compacted and the external casing is completely full.The final vacuum is then drawn, typically around 10⁻¹ to 10⁻³ mbara, to ensure effective thermal insulation of the cryogenic storage or cold box. FR-A-2917490 describes an enclosure according to the preamble of claim 1 and a method according to the preamble of claim 10 using a conventional thermal insulator.

[0007] According to one object of the invention, a thermally insulated enclosure is provided according to claim 1.

[0008] According to other optional aspects: The walls of the enclosure are insufficiently thick to maintain a vacuum if the insulation had such high compressive strength that its volume would decrease by more than 10%, or even 5%, or more than 1% if the enclosure were evacuated at a pressure below 10⁻¹ mbar. The beads are made of glass and / or perlite and / or vermiculite. The enclosure has a minimum volume of 12 m³. The enclosure consists of a container, which is a standardized, parallelepiped-shaped metal box designed for transporting goods, equipped at at least one corner with a gripping device for securing and transferring it. The equipment includes, or is at least one, column suitable for heat and / or mass exchange and / or at least one heat exchanger and / or at least one storage unit and / or at least one phase separator. The equipment is a column or a heat exchanger, the equipment being in the shape of a parallelepiped.

[0009] According to another aspect of the invention, a filling method according to claim 8 is provided.

[0010] Preferably, the enclosure is filled with marbles through an opening formed by removing a sheet metal part of a wall of the enclosure or constituting a wall of the enclosure.

[0011] According to another aspect of the invention, a method according to claim 10 is provided.

[0012] The volume of the assembly formed by the multiplicity of balls would be reduced by at most 10%, or even 5%, preferably by at most 1%, if the assembly formed by the multiplicity of balls is subjected to an additional pressure of 0.1 MPa; this means that for a multiplicity of balls already at atmospheric pressure, if they were subjected to an additional pressure of 0.1 MPa, the claimed volume reduction would be observed at most.

[0013] The invention has, among other things, the advantages of reducing the time and cost of setting up the insulated enclosure, reducing the mass of the enclosure and avoiding problems of deformation of the enclosure.

[0014] The invention consists of a parallelepiped-shaped enclosure whose thermal insulation allows it to withstand atmospheric pressure when under vacuum. The manufacturing process involves completely filling the outer shell with a powdered material in the form of spherical or nearly spherical beads, preferably by gravity. The outer shell is then evacuated.

[0015] Because the material in the form of spherical beads is only slightly compressible, it withstands the mechanical stress of the vacuum, while relying on the internal components of the outer casing (internal storage, distillation column, heat exchanger, piping, separator pots, valves, etc.) without deforming the outer casing wall: this also prevents deformation of the outer casing itself. The outer casing can therefore be simplified into a simple, airtight "skin" containing the powdered material to control the insulation distances before vacuuming.

[0016] The airtight outer casing is not designed to withstand a vacuum (i.e., to withstand the atmospheric pressure of 1 bar applied to its outer surface). Pressure forces are transmitted through the insulation by means of a powdery material with little or no compressibility (i.e., whose compressive strength exceeds the mechanical force to be transmitted), typically glass beads (for example, 3M® product K1), perlite, or vermiculite. The beads used have a diameter of less than 1 mm, or preferably 800 or 600 micrometers, or even 500 or 120 micrometers. Preferably, the beads used have a diameter greater than 10 micrometers, or even greater than 100 micrometers. They can be hollow.

[0017] The enclosure is filled by pouring the marbles through an opening; the enclosure can be lying down or standing upright. This opening can be created by removing a metal sheet from one of the enclosure's walls, such as the roof. Alternatively, an opening can be made in the outer casing of the enclosure to allow the marbles to be inserted. The outer casing is then completely filled with marbles, primarily by gravity. Vibrations or tapping on the casing, for example with a hammer or mallet, can be used to facilitate the flow of marbles throughout all areas of the outer casing, including less accessible or "hidden" areas such as under a support or pipe, and to minimize the effect of sloping. The outer casing can be rotated to ensure that the entire "empty" volume is properly filled by gravity, by placing it in different positions.

[0018] The thin outer casing can have a degree of rigidity to maintain a controlled geometric shape during the filling with powdered insulating material, ensuring proper insulation distances from internal equipment. Spacers or local supports can also be incorporated to dimensionally contain the material during filling.

[0019] Once filled to the brim, the enclosure is closed. This can be done by replacing the previously removed sheet metal. Alternatively, a typically flat cover, such as a simple welded sheet of metal, can be securely fixed over the opening. The sheet metal or cover (preferably) is not designed to withstand the vacuum (i.e., atmospheric pressure of 1 bar) and must therefore rest on the balls to prevent any unacceptable deformation during the evacuation of the enclosure; the sheet metal or cover thus becomes part of the enclosure's structure. Alternatively, the enclosure can be filled through a filling port, which is then closed with a solid flange.

[0020] Once the enclosure is closed, the single final vacuum can be pulled, typically around 10⁻¹ to 10⁻³ mbara to ensure efficient thermal insulation of the cryogenic storage or cold box, without having to add insulating product and without fear of deforming the thin walls, the pressure forces being taken up by the insulation, while relying on the internal equipment of the external envelope (internal storage, distillation column, exchanger, piping, separator pots, valves, ...).

[0021] The set of spherical balls filling the enclosure has a crush resistance such that its volume would be reduced by at most 10%, or even 5%, preferably at most 1%, if the balls are subjected to an additional pressure of 0.1 MPa, which is typically the pressure experienced if the enclosure is evacuated to a pressure less than 10 -1 mbara, and assuming that the casing does not provide mechanical resistance. For all applications, there is the material saving of the outer casing (thinner thickness) and the advantage of a single vacuuming operation. This applies to a distillation apparatus where distillation takes place at a temperature below 0°C, or even at a cryogenic temperature, comprising a distillation column and / or heat exchanger contained within a rectangular cold box or a simple container, such as a standard-sized, airtight container. It also applies to cryogenic storage where the interior temperature is below 0°C, or even at a cryogenic temperature, and where a gas or liquid reservoir is contained within an insulated rectangular enclosure, which could be a standard-sized container. A truck carrying cryogenic storage as described above is also an option.

[0022] The invention will be described in more detail with reference to the figure which represents an enclosure according to the invention.

[0023] There figure 1 illustrates a cryogenic distillation air separation apparatus comprising several isolated chambers.

[0024] A first insulated enclosure in the shape of a parallelepiped, CB1, contains an air distillation column C, here cylindrical, but which can have other geometries. The enclosure CB1 has a volume of at least 12 m³ and also contains a subcooler SR and pipes D3 that facilitate vacuuming. The space around the column equipment is filled at least three-quarters, preferably completely, with a multitude of spherical beads made of thermally insulating material, and possibly hollow, having a crush resistance preferably such that their volume would be reduced by no more than 10%, or even 5%, preferably no more than 1%, if the enclosure is evacuated at an additional pressure of 0.1 MPa.

[0025] The first CB1 enclosure is a standardized, parallelepiped-shaped metal box designed for the transport of goods, equipped at at least one corner with a gripping piece allowing it to be secured and transshipped.

[0026] The first CB1 enclosure can contain a main heat exchanger to cool the air intended for the column and a D3 distributor which facilitate vacuuming.

[0027] A second isolated chamber CB2 contains a condenser R and distributors which facilitate vacuuming D1, D2.

[0028] A third isolated chamber CB3 contains filters F which filter a liquid from column C going to pump P and a distributor D4 which facilitate vacuuming.

[0029] The device may include another insulated enclosure containing only the main heat exchanger, the insulation being in the form of beads.

[0030] The air distillation column C, designed to operate at a pressure higher than atmospheric pressure, is placed inside the rectangular enclosure CB1, for example, a container with standard dimensions. The distillation column C is connected to piping to supply it with air, to transfer any reflux liquids, and to transport the distillation products. The enclosure CB1 has a large opening in one wall. One wall may even be completely open. The enclosure is filled with beads until it is completely full and then shaken to compact the beads tightly. The beads used may be, for example, 3M® K1 glass microspheres with a density of 0.125 g / cm³.The wall is closed, for example by welding the wall or part of the wall in place, and the enclosure is evacuated to a pressure of less than 1 bara, typically a pressure of less than 10⁻¹ mbara, or even less than 10⁻³ mbara.

[0031] It is possible that the CB1 enclosure may contain thermal insulation materials other than the beads. For example, instrumentation or supports located within the enclosure may be insulated with Durostone® Epoxy EPM203, or a layer of insulation may cover equipment within the enclosure, provided the thermal insulation used has compression properties at least equivalent to those of the beads. Nevertheless, the beads alone will constitute at least three-quarters of the insulation by volume.

[0032] In the example, the enclosure has an outer casing containing equipment such as a column. Alternatively, the equipment could be a rectangular box itself containing a column or a heat exchanger. In this case, the space between the rectangular box and the outer casing is filled with a multitude of spherical beads made of thermally insulating material, possibly hollow, having a crush resistance preferably such that their volume would decrease by no more than 10%, or even 5%, preferably no more than 1%, if the assembly formed by the multitude of beads is subjected to an additional pressure of 0.1 MPa.

[0033] The space between the rectangular box and the column is uninsulated and not vacuum-sealed. The space between the rectangular box and the outer casing is filled by removing a sheet metal panel that forms part of a wall of the enclosure, such as the roof. Alternatively, a cover can be used, as described above.

Claims

1. A thermally insulated enclosure (CB1) containing at least one piece of equipment (C, SR) intended to operate at a temperature below 0°C, or even at a cryogenic temperature, and adapted to carry out a separation process at a cryogenic temperature, the space inside the enclosure being intended to be at a pressure lower than atmospheric pressure and being filled, preferably completely filled, with a thermal insulation material, characterized in that it is in the shape of a parallelepiped and in that, the thermal insulation material is composed, for at least three-quarters of its volume, of a multiplicity of spherical beads of thermally insulating material, and possibly hollow, having a diameter of at most 1 mm and having a crush resistance such that the volume of the assembly formed by the multiplicity of beads would be reduced by at most 10%, or even 5%, preferably by at most 1%, if the assembly formed by the multiplicity of beads were subjected to an additional pressure of 0.1 MPa.

2. The enclosure according to claim 1, wherein the walls have an insufficient thickness to withstand a vacuum if the insulation material had a crush resistance such that its volume would be reduced by more than 10%, or even 5%, and where applicable by more than 1%, if the enclosure were evacuated to a pressure below 10-1 mbara.

3. The enclosure according to one of the preceding claims, wherein the beads are made of glass.

4. The enclosure according to one of the preceding claims having a minimum volume of 12m3.

5. The enclosure according to one of the preceding claims, constituted by a container (CB1) which is a parallelepipedal metal box with standardized dimensions designed for the transport of goods, provided at at least one corner with a gripping piece for securing and transshipping it.

6. The enclosure according to one of the preceding claims, wherein the equipment comprises or is at least one column adapted to carry out a heat and / or mass exchange (C) and / or at least one heat exchanger (SR) and / or at least one storage unit and / or at least one phase separator.

7. The enclosure according to claim 6, wherein the equipment is a column (C) or a heat exchanger (SR), the equipment being in the shape of a parallelepiped.

8. A method for filling an enclosure according to one of the preceding claims 1 to 7, wherein at least one piece of equipment is placed in the enclosure, the enclosure (CB1) is filled with the multiplicity of beads, the enclosure is closed and the space inside the enclosure is at least partially evacuated, preferably in a single evacuation step.

9. The method according to claim 8, wherein the enclosure (CB1) is filled with beads through an opening formed by removing a plate forming part of a wall of the enclosure or constituting a wall of the enclosure.

10. A separation process at a temperature below 0°C by distillation and / or washing using a thermally insulated enclosure (CB1) containing at least one piece of equipment (C, SR) operating the separation which functions at a temperature below 0°C, or even at a cryogenic temperature and at a preferably super-atmospheric pressure, the space inside the enclosure is evacuated to a pressure lower than atmospheric pressure, preferably lower than 10-1 mbara, and being filled with thermal insulation material, characterized in that the enclosure is in the shape of a parallelepiped, the thermal insulation material being composed for at least three-quarters of its volume, of a multiplicity of spherical beads of thermally insulating material, and possibly hollow, having a diameter of at most 1 mm and having a crush resistance such that the volume of the assembly formed by the multiplicity of beads would be reduced by at most 10%, or even 5%, preferably by at most 1%, if the assembly formed by the multiplicity of beads were subjected to an additional pressure of 0.1 MPa.