The present invention relates to a thermally insulating capsule for regulation units in a low temperature installation, in particular for valves in a cryogenic installation.

Prior art

For thermal insulation of a unit in such installations it is known to build the insulation, of cell glass or mineral wool, for example, at the site of usage by using insulation elements and prefabricated cups. The elements are glued together around the unit while being kept together by tension exerting devices, such as rubber bands, tensioning bands, straps or the like. Cavities facing the unit are filled with mineral wool or similar, in order to prevent circulation of air during operation of the installation. On the outside of the insulation is placed an air barrier, for instance made of aluminium foil or similar, in order to prevent air flowing in towards the insulation and causing formation of ice, and on the outside of the air barrier a shield is fitted, which may consist of cell rubber or mineral wool. For mechanical protection and for preventing ingress of water an external steel capsule is fitted.

When insulating large units, such as cryogenic valves, problems when fitting the cell glass elements will occur if there is not sufficient foundation for the elements and joints which are not sealed may result.

The insulation consists of several layers, and the work of fitting' the plurality of elements included is very labour demanding. The work is carried out at the site of usage, and the quality of the insulation will depend on the weather conditions.

During a possible disassembling the insulation will be damaged, and consequently this approach is not very friendly as regards the environment. The insulation work cannot start before the fitting of the unit has finished. As the start-up of the installation usually is a matter of rush, the insulating work takes place in a limited period of time, which may be detrimental to the insulation quality. A poor quality will only be discovered after the start-up of the installation, and may appear as formation of ice on the unit. This may cause shut down for improving the insulation.

Such capsules may, inter alia, be employed for large units having main dimensions in the order of up to several meters, and a large amount of materials may be consumed, which have to be replaced if the capsule is dismantled and re-assembled. The present invention

By the present invention it has been provided a thermally insulating capsule for regulation units in a low temperature installation, in particular for valves in a cryogenic installation, and by which the fitting problems are substantially reduced compared with the prior art approaches. The thermally insulating capsule according to the invention comprises at least two prefabricated capsule units which may be sealingly fitted together, each capsule unit containing all of the thermally insulating elements, layers for preventing transport of air between the internal and external environment of the capsule and for providing external protection, to be included in the finished capsule. When the necessary number of such capsule units has been joined together, the capsule is finished, containing all the necessary layers for insulation, layers for preventing transport of air between the internal and external environment and for external protection. The assembling can be carried out nearly without any possibility of erroneous assembly. The capsule units will be shaped such that they fit together only in one particular manner, and an attempt of erroneous assembly will immediately be evident in that the units do not fit together in the mutual erroneous positions in which assembly was attempted. Each capsule unit comprises all the elements which are to be included in the finished capsule, whereby omission of any of the elements during assembly at the site of usage is not possible. Therefore, less strict requirements regarding the skills of the workers are demanded, compared to the building of capsules carried out by fitting elements one by one, and the assembly may be carried out far more rapidly than by such fitting of elements, while the risk of erroneous assembly being at a minimum. The production of the elements may be carried out at a favourable temperature in a factory.

Usually it will be sufficient to produce the capsule from two capsule units, which in their assembled state enclose a regulation unit, such as a valve. The capsule units may have such a shape that they together form a cavity adapted to the regulation unit. It is, however, not a presupposition that the capsule encloses the unit without leaving any void inside the capsule between the inside of the capsule and the unit.

The regulation unit will usually be coupled to pipelines which protrude from the capsule, and each capsule unit will be equipped with an opening half which together surround a pipeline when assembled. In other words the partition between the capsule units extends along the centre of the pipelines. Gaskets may also be glued to the capsule units, possibly such that the gaskets protrude on the outside of the capsule units and may be tied around the pipelines. Alternatively, sealing rings may be fitted on the pipelines beforehand, and the opening halves may be adapted to the sealing rings, whereby sealing is automatically formed during the assembly. The installers do not need to make sure that the capsule includes all the elements it is intended to include, or that the elements are correctly sized and located, because all these elements are already correctly sized and placed in the prefabricated capsule units.

The capsule may be assembled and disassembled several times, and this approach is, consequently, resource saving and friendly to the environment.

Explanation of drawings The invention will in the following be explained more detailed by means of examples of embodiments shown on the accompanying drawings.

Fig. 1 shows in perspective a capsule according to the invention, composed of two capsule units. Fig. 2 shows in perspective a capsule unit included in the capsule of Fig. 1.

Fig. 3 shows in perspective another embodiment of a capsule according to the invention.

Fig. 4 shows in perspective one of the capsule units of Fig. 3, with an external wall of steel which may be covered by cell rubber, and with gaskets inserted in openings for pipelines and in an opening for a valve stem.

Fig. 5 shows the embodiment of Fig. 4 of a capsule unit according to the invention, but without any planar gasket covering the side which is to face the other capsule unit.

Detailed description of examples of embodiments In the figures the same reference numerals are used for analogous or equivalent elements in all the embodiments.

The capsules shown in the Figs. 1 and 3 are shown as made of two analogous but mirror imaged capsule units 1, 2. However, the capsule elements do not need to be analogous, as their shapes need to be adapted to the regulation unit which they are to enclose.

The capsule shown in Fig. 1 is composed of two capsqle units 1 and 2, of which capsule unit 1 is shown in Fig. 2. The capsule units 1 and 2 enclose a regulation unit (not shown). In the example it is presupposed that the regulation unit has pipelines for connection to other parts of the installation, and for this purpose each of the capsule units 1 and 2 have respective openings 3 for the pipelines, In these openings may be placed sealing rings 6 composed of two halves and surrounding the pipelines, or sealing rings may be glued in the openings and may protrude therefrom, whereby the sealing rings are lying against the pipelines and can be tightened thereagainst, for instance by means of straps or rings. It is also presupposed that the regulation unit is to be regulated by rotation of a stem, and for this purpose a hole 4 for such a stem is formed in a neck 5. The sealing ring 6 is shown protruding somewhat from the opening 5 3, whereby it may be tied and exert a pressure against the pipeline. On the surfaces of the capsule units lying against each other planar gaskets 8 are placed, which during the assembling are pressed somewhat together. On the outside of the capsule units 1, 2 a protective and air obstructing layer 14 is applied, which may consist of glass fiber reinforced polyester. Such a layer 14 will also be flame resistant. 0

The assembling can be carried out in that the capsule units, having planar gaskets applied on the surfaces which are to face one another, are brought in correct mutual positions and pressed together, for instance by use of surrounding straps, or in that tightening tools are applied on the outside, for compressing the planar gaskets 8.5

Fig. 2 shows capsule unit 1 included in the capsule shown in Fig. 1. Capsule unit 1 shown in Fig. 2 is made of two or more layers, which do no appear from the figure because they are covered by the external layer and the gasket 8. The layers may be thermal insulation, layers as barrier against transport of air and mechanical protectiono layers, respectively. On the inside of the wall formed by the layers a layer 9 for preventing transport of air may be applied. Cell glass may be used as thermal insulation.

The insulation layers may consist of cell glass elements glued together. The layers for5 preventing transport of air and the layers for mechanical protection may consist of flame resisting glass fiber, possibly with UV hardening polyester. These materials are mentioned merely as examples of suitable materials, and persons skilled in the art will be aware of other suitable thermally insulating materials and materials for stopping air and for mechanical protection. It will be appreciated that more than two layers may beo used.

Fig. 3 shows an embodiment where the external wall oχthe capsule consists of steel, the outer surface of which may have an applied layer of cell rubber, and with an air barrier in the form of a polymeric fabric on the outside of the cell rubber layer. 5

The capsule shown in Fig.3 is composed of two capsule units 1 and 2, enclosing a regulation unit (not shown ). Each of the capsule units 1 and 2 have been formed with respective halves of openings 3 for pipelines. In these openings gaskets 6 can be placed which are glued into the openings and may protrude therefrom, whereby the gaskets 6 will be lying against the pipelines and may be tied such that the gaskets 6 are pressing against the pipelines. Also here it is presupposed that the regulation units are to be regulated by rotation of a stem, and for this purpose a hole 4 for such a stem is formed in a neck 5. Gaskets have been place in the hole 4. On those surfaces of the capsule units which face each other planar gaskets 8 have been placed, which will be compressed during the assembly.

Figs. 4 and 5 show one of the capsule units of Fig. 3. Inside of an external steel wall 10 two or more layers 11, 12, 13 (shown in Fig. 5) of thermally insulating material, for instance cell rubber, are located. These layers do not appear from Fig. 4, because a planar gasket 8 covering the cell rubber layers is applied on the surfaces which are to face each other in the assembled condition. These layers are in tight engagement against each other and against the steel wall 10. Also in this embodiment gaskets 6 may be placed and possibly glued to the capsule units, in the openings 3 for pipelines and in the hole 4 for the valve stem. Fig. 4 shows an external layer 7, which may be fastened by gluing and consist of cell rubber.

Fig. 5 shows the capsule unit shown in Fig. 4, but without the planar gasket 8. Inside of an external steel wall 10 several layers 11, 12, 13 of a thermally insulating material are located. In the example shown three such layers are present. These are in tight engagement against one another and against the steel wall 10. The layers 11, 12, 13 may for instance consist of cell rubber. Also in this embodiment gaskets 6 may be placed and possibly glued to the capsule units, in the openings 3 for pipelines and in the hole 4 for the valve stem. Fig. 5 also shows an external air barrier layer 7, which may be fastened by gluing and consisting of polymeric fabric.

An advantage of using cell glass as thermally insulating material is that it is not inflammable. This may be a requirement for some applications.

The capsule units are adapted to each other in pairs, and can only be assembled together in one particular manner. Thus, it is nearly impossible to carry out an erroneous assembling.

It will be appreciated that the thickness of the respective layers will be adapted to the main dimensions of the capsule. The capsule can be utilized in installations having very low temperatures, for instance -150° or lower.