Insulation arrangement

Abstract

An arrangement of insulation within a container to prevent heat leakage from the ambient to an apparatus located within the container that operates at a cryogenic temperature. The arrangement of insulation includes bulk insulation filling the container and an insulation layer that is located within the container, between the apparatus and the container. The insulation layer as opposed to the bulk insulation has a lower thermal conductivity. An exterior region of the apparatus is situated closer to an opposite container wall region of the container than remaining exterior regions of the apparatus. The insulation layer is sized to only insulate the exterior region of the apparatus from heat leakage from the opposite container wall region. The insulation layer can be formed of an aerogel.

Claims

1. An arrangement of insulation within a container having an internal positive pressure to prevent heat leakage from the ambient to an apparatus located within the container and operable at cryogenic temperature, wherein: the container is a cold box of an air separation plant, and has a rectangular transverse cross-section and four connected sidewalls; the apparatus has first exterior regions located opposite to the sidewalls of the container and situated closer to the sidewalls than remaining exterior regions of the apparatus; and, the apparatus includes a distillation column and a heat exchanger, the distillation column having a cylindrical transverse cross-section, and the heat exchanger having a rectangular transverse cross-section and operable at a warmer temperature than that of the distillation column; the arrangement of insulation comprising: first, second, third, fourth, fifth and sixth insulation layers; and, bulk insulation disposed within said container and filling portions of the container that are not filled by the apparatus and the insulation layers including portions of the container between the insulation layers and the sidewalls of the container; wherein the first, second, third and fourth insulation layers are disposed apart from the sidewalls of container and attached to the first exterior regions of the apparatus only between the first exterior regions of the apparatus and the closer situated sidewalls of the container, such that: the first and second insulation layers cover two adjacent segments of the outer cylindrical surface of the distillation column located closest to a first sidewall and a second sidewall of the four connected sidewalls of the container; and, the third and fourth insulation layers cover two opposite first and second sides of the heat exchanger located closest to the second sidewall and a third sidewall of the four connected sidewalls of the container; and wherein: the fifth insulation layer covers a fourth of the four connected sidewalls of the container, the fourth sidewall located opposite to a third side of the heat exchanger which connects the opposite first and second sides of the heat exchanger; the sixth insulation layer is located on a fourth side of the heat exchanger located opposite to said distillation column to insulate the distillation column from heat leakage from the heat exchanger to the distillation column; and, the insulation layers have a thermal conductivity lower than that of the bulk insulation.

2. The arrangement of insulation of claim 1, wherein each of the insulation layers is an aerogel blanket insulation.

3. The arrangement of insulation of claim 1, wherein each of the insulation layers is a fibrous mat containing aerogel in which the fibrous mat reinforces the aerogel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) While the specification concludes with claims distinctly pointing out the subject matter that Applicants regard as their invention, it is believed that the invention will be better understood when taken in connection with the accompanying drawings in which:

(2) FIG. 1 is a schematic, sectional view of an insulation arrangement in accordance with the present invention;

(3) FIG. 2 is an alternative embodiment of an arrangement of insulation in accordance with the present invention; and

(4) FIG. 3 is an alternative embodiment of an arrangement of insulation in accordance with the present invention.

DETAILED DESCRIPTION

(5) With reference to FIG. 1, an arrangement of insulation is illustrated within a container 10 that is not air tight and therefore has an internal positive pressure that is at an atmospheric pressure.

(6) Container 10 is of cylindrical configuration and as such has a cylindrical side wall 12. Located within container 10 is an apparatus 14 that is designed to operate at a cryogenic temperature. For instance, apparatus 14 could be a distillation column of an air separation unit in which air is rectified to cryogenic temperatures. It is to be noted that in such apparatus, air is cooled to at or near its dew point and then introduced into a distillation column in which an ascending vapor phase containing the lighter components of the air, for example, nitrogen, is in part liquefied at the top of the column to reflux the column with liquid. The descending liquid phase contacts the ascending vapor phase through a contact element such as structured packing or sieve trays to produce mass transfer between the phases. As a result, the ascending vapor phase becomes evermore rich in the lighter components such as nitrogen than the descending liquid phase becomes evermore rich as it descends with oxygen.

(7) In order to reduce heat leakage from the ambient through the container wall 12 to apparatus 14, an arrangement of insulation is provided in accordance with the present invention. The arrangement of insulation consists of bulk insulation 16, for instance, PERLITE, microcel, rockwool which is simply poured into container 10. In addition to that, an insulation layer 18 is located within the container between the apparatus 14 and the container wall 12. The insulation layer 18 has a lower thermal conductivity than that of the bulk insulation 16. For example, the insulation layer 18 can be formed of aerogel. Fiberglass, polyurethane or polyisocyanurate layers are also possible.

(8) It is apparent from FIG. 1, apparatus 14 is off center. As such, an exterior region of the apparatus 14, situated between arrowheads A, is located closer to an opposite container wall region of container wall 12, located between arrowheads B, than remaining exterior regions of apparatus 14. The insulation layer 18 is sized to only insulate the exterior region between arrowhead A of the apparatus 14 from heat leakage from the opposite container wall region between arrowheads B. As such, the advantages of minimizing the use of expensive insulation such as aerogel are realized. In addition, if one views the remaining wall regions, they are located further from the exterior surface of apparatus 14. As such, there exists a sufficient depth of bulk insulation 16 to provide the insulation. Hence, the width of insulation layer 18 is sized so that adjacent regions will have a sufficient depth of the bulk fill insulation 16 to in turn sufficiently insulate apparatus 14 from heat leakage from remaining container wall regions of container wall 12. The calculation of the necessary width of insulation layer 18 and its thickness is a manner of conventional calculation that is known by those skilled in the art.

(9) Thus, apparatus 14 can be located closer to container wall 12 than otherwise would have been possible without the insulation layer 18. As a result, container 10 can be made smaller than would otherwise have been possible with the use of the bulk insulation 16 alone.

(10) Preferably, the insulation layer 18 is in a blanket form and thus constitutes a layer which is attached to the exterior surface of apparatus 14. Although less preferred, the insulation layer 18 could be located on the opposite container wall region B. Within the scope of the present invention, it would even be possible to locate an insulation layer 18 between the exterior region designated by arrowheads A and the interior region situated between arrowheads B.

(11) Although insulation layer 18 has been discussed above with respect to an aerogel blanket, other forms of aerogel are possible such as a pellet form retained between rigid or semi-rigid walls, a physical intact solid form, a fibrous mat containing the aerogel in which the fibrous mat reinforces the aerogel. Additionally, insulation layer could be made from a sheet of fiberglass or any other material having a lower thermal conductivity than the bulk fill insulation 16.

(12) With reference to FIG. 2, apparatus 14 is located within a container 20 that is of rectangular transverse cross-section and that has four connected side walls 22, 24, 26 and 28. In this embodiment of the present invention, apparatus 14 is centered within container 20. However, as a result of the intersection between the cylindrical configuration of apparatus 14 and the rectangular configuration of container 20, there will be four opposed exterior regions located between the respective arrowheads A.sup.1, A.sup.2, A.sup.3 and A.sup.4 of apparatus 14 that is situated closer to interior wall regions of container walls 22, 23, 26 and 28 designated by the regions located between arrowheads B.sup.1, B.sup.2, B.sup.3 and B.sup.4 respectively. Thus, in accordance with the present invention, insulation layers 30, 32, 34 and 36 will cover four adjacent equal segments of the exterior surface of apparatus 14, namely, the exterior regions located between arrowheads A.sup.1, A.sup.2, A.sup.3 and A.sup.4.

(13) With reference to FIG. 3, a container 40 is illustrated that is of rectangular transverse cross-section and that has four connected side walls 42, 44, 46 and 48. Container 40 constitutes a cold box in which the apparatus is a distillation column 49 of an air separation unit. Additionally, the apparatus also includes a heat exchanger 50. Heat exchanger 50, is typically of plate-fin design and as such, constitutes a structure that geometrically has four rectangular side walls 52, 54, 56 and 58 that are connected at the top and bottom by rectangular top and bottom walls of which top wall 60 can be seen in the illustration.

(14) Heat exchanger 50 is used to cool the air being distilled within the cryogenic rectification column 14. However, it also operates at a higher temperature being that it is cooling the incoming air. Thus, in the cold box or container 40, there exists heat leakage from the ambient through the container walls 42, 44, 46 and 48 and also potentially heat leakage from heat exchanger 50 to distillation column 14.

(15) Distillation column 49 is off center. As such, there exists two adjacent segments of the outer surface of the distillation column 49, located between arrowheads C.sup.1 and C.sup.2, that are closer to opposed wall regions of container walls 42 and 48, located between arrowheads D.sup.1 and D.sup.2.

(16) With respect to heat exchanger 50 there exists three exterior regions of heat exchanger sides 52, 54 and 56, located within brackets E.sup.1, E.sup.2 and E.sup.3, that exists closer to opposite wall regions of container walls 42, 44 and 46 that are designated by arrowheads D.sup.3, D.sup.4 and D.sup.5. Insulation layers 62 and 64 are provided that cover sides 52 and 56, respectively, of heat exchanger 50. An insulation layer 66 is provided that is attached to side wall 44 to increase the insulation between heat exchanger side 54 and side wall 44.

(17) In order to allow distillation column 49 to be positioned in a close proximity to heat exchanger 50, an insulation layer 68 is provided on side 58 of heat exchanger 50 that is located opposite to an exterior surface of distillation column 49, situated between arrowheads C.sup.3.

(18) While the present invention has been described with reference to a preferred embodiment as will occur to those skilled in the art, numerous changes, additions and omissions may be made without departing from the spirit and scope of the present invention.