OA16615A - Cold box design providing secondary containment. - Google Patents

Abstract

The present invention relates to cryogenic fluids. In another aspect, the present invention relates to additional protection of an apparatus containing equipment capable of operating at cryogenic temperatures and containing cryogenic materials. An apparatus includes : (a) a primary enclosure defining an internal volume, wherein the primary enclosure includes primary walls, a primary ceilling, a primary floor, and a vapor venting system, wherein the primary enclosure is fabricated from a low temperature alloy, wherein at least a portion of the primary floor forms a slope, wherein the slope from a hydrocarbon outlet, wherein a perforated plate is located on top of the hydrocarbon outlet, wherein the perforated plate is fabricated from a low temperature alloy; and (b) a fire retardant agent applied to the exterior surface of the primary enclosure.

Description

COLD BOX DESIGN PROVIDING SECONDARY CONTA1NMENT CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priorîty to and benefit of U.S. Provisionai Patent Serial

No. 61/474,479 filed on April 12, 2011, and U.S. Patent Serial No. 13/438,295 filed April 3, 2012, the entirc disclosure both of which are incorporated herein by reference.

FIELD OF THE INVENTION [0002] The présent invention relates to additional protection of an apparalus containing equipment capable of operating at cryogénie températures and containing cryogénie materials. In another aspect, the présent invention relates to an apparatus for preventing heat leakage

BACKGROUND OF THE INVENTION [0003] In many industrial applications, an apparalus that is designed to opcrale at cryogénie températures is located within an insulated container to minimize heat leakage from the ambient to the apparatus.

[0004] An example of an apparatus that has operational température requirements is a cryogénie distillation apparatus in which air is compressed, purified and then cooled to a température at or near ils dew point for distillation in one or more distillation columns to separate lighter components such as nitrogen and argon from heavier components such as oxygen. The incoming air is cooled against product streams such as nitrogen and oxygen within a main heat cxchanger.

[0005] Another example is a device for liquefying nalural gas whereby gas from a high pressure pipeline is expanded, cooled and condensed to produce a liquefied nalural gas (LNG) product.

[0006] In order to mainlain the low températures required for such cryogénie operations, the equipment can bc placed in a container known as a cold box. Such a container opérâtes al a positive pressure, that is, the container is not sealed to the ambient environment. Bulk fill insulation, ordinarily in particuiate form, is introduced into the container to provide insulation. Such bulk fill insulation, for example pcrlite, inhibits both convective and radiative heat transfer und constrains the heat transfer occurring through conduction.

[0007] A minimum insulation thickness is required to prevent excessive heat leakage.

Typically, the container may be fabricated from a carbon steel material, which may not be

suitable for exposure to cryogénie températures. However, a minimum insulation thickness is required to avoid brittlc fuilure of the container walls and structural supports. As can be appreciated, the lower the thermal conductivily of the insulation, the smaller the minimum thickness of insulation, and the smaller the container due to less insulation.

[0008] While current containers exposed to cryogénie opérât ions.pro vide protection from exlernal corrosion, additional protection from external fi res would be désirable, particularly for cold boxes installed in a marine environment. Additionally, secondary leakage protection would be désirable for a location with limited space, which includcs marine envîronments.

[01)09] Currenlly, cold boxes containing cryogénie processing equipmenl provide adéquate lient leakage properlies and provide an inerl environment to préserve the equipment.

However, the current state of cold box equipment fails to provide any signifîcant protection from external fires or secondary leakage protection, both of which are particularly valuable for situations where plot space is very limited, such as a marine environment.

SUMMARY OF THE INVENTION [0010] In one embodiment of the présent invention, an apparatus includes: (a) a primury enclosure defîning an internai volume, wherein the primary enclosure includes primary walls, a primary ceiling, a primary floor, and a vapor venting system, wherein the primary enclosure is fabricatcd from a low température alioy, wherein at least a portion of the primary floor forms a slope, wherein the slope from a hydrocarbon outlet, wherein a perforaled plate is located on top of the hydrocarbon outlet, wherein the perforaled plate is fabricated from a low température alioy; and (b) a fîre retardant agent applied to the exterior surface of the primary enclosure.

[0011] In another embodiment of the présent invention, an apparatus includes: (a) a primary enclosure defining an internai volume, wherein the primary enclosure includes primary walls, a primary ceiling, a primary floor, and a vapor venting system, wherein the primary enclosure is fabricated from a low température alioy, wherein at least a portion of the primary floor forms a slope, wherein the slop forms a hydrocarbon outlet, wherein a perforaled plate is located on top of the slope, wherein the perforaled plate is fabricated from a low température alioy; (b) a secondary enclosure surrounding the primary enclosure defining a second internai volume, wherein the secondary enclosure includes secondary walls, a secondary ceiling and a secondary floor, and (c) a fire retardunt agent applied to the exterior surface of the secondary enclosure.

[0012] In yet another embodiment of the présent invention, an apparatus includes: (a) a primary enclosure defining an internai volume, wherein the primary enclosure includes primary walls, a primary ceiling, a primury floor, and a vapor venting system, wherein at least a portion of the primary floor forms a slope to for hydrocarbon drainage, wherein a perforaled plate is located on top of the slope, wherein the perforaled plate is fabricated from a low température alioy; (b) a secondary enclosure surrounding the primary enclosure defining a second internai volume, wherein the secondary enclosure includes secondary walls, a secondary ceiling and a secondary floor; and (c) a fire retardant agent applied to the exterior surface of the secondary enclosure.

BRIEF DESCRIPTION OFTHE DRAWINGS [0013) The invention, together with further advanluges thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings in which:

[0014] FIG. 1 is a schcmatic représentation of an apparatus in accordance with an embodiment of the présent invention.

[0015] FIG. 2 is a schematic représentation of an apparatus ‘in accordance with an embodiment of the présent invention.

DETAILED DESCRIPTION OFTHE INVENTION [0016] Référence will now be made in detail to embodiments of the invention, one or more cxamples of which are illustrated in the accompanying drawings. Each example is provided by way of explanalion of the invention, not as a limitation of the invention. Il will be apparent to those skilled in the art that various modifications and variation can be made in the présent invention without departing from the scope or spirit of the invention. For instances, features illustrated or described as part of one embodimenl can be used in another embodiment to yield a still further embodimenl. Thus, it is intended that the présent invention cover such modifications and variations thaï corne within the scope of the appended daims and their équivalents.

[0017] FIG. 1 depicts a primary enclosure defining an internai volume. The primary enclosure can fonction as a thermal insulator capable of containing equipment operating at cryogénie températures. For instance, the primary enclosure can be a cold box. Additionally, the primary enclosure may contain several pièces of equipment, such as heat exchangcr(s), separator(s) and/or column(s).

[0018] The primary enclosure can be fabricated from various malerials. In an embodiment, the primary enclosure is fabricated from a material dcsîgned to operale at cryogénie températures, i.e., a low température alloy. Low température alloys can include stainlcss steels and high nickel steels. Low température alloys provide the necessary protection against heat leakage and maintaîn integrity if exposed to cryogénie materials.

[0019] As depicted in FIG. 1, the primary enclosure includes walls 102, a primary ceiling

104, a primary floor 106, and a vapor venting System 110. As previously menltoned, the internai volume of the primary enclosure can include various pièces of equipment. For cryogénie operations, the equipment may be surrounded by bulk fill insulation. Examples of bulk fill insulation thaï may be used with the instant invention include perlite, silica aerogels, or any combination thereof. Alternatively, the enclosed volume in the box may be empty and the equipment and internai walls of the enclosure may be insulated to reduce the heat transfer to the pièces of equipment, [0020] In FIG. 1, at least a portion of the primary floor 106 forms a slope to a hydrocarbon outlet 108 to encourage hydrocarbon drainage. This provides secondary containment for cryogénie liquîds in the event thaï a pièce of equipment, piping or instrumentation inside the cold box develops a leak. Cold boxes normaliy include an inert &

atmosphère so the druining of polenlial leuks along with the inerl atmosphère providcs an additional level of safety. A perforated plate 110 is located on top dî the of the hydrocarbon outlet 108. The perforated plate prevents the bulk fil! insulation within the internai volume from exiling the primary enclosure. If the internai equipment is insulated and no bulk fill material is used, the perforated plate is not required. In an embodiment, a screen covers the perforated plate. The area where the liquid may be collectcd has instrumentation to detect the presence of liquids and either automatically or through manual intervention, allows the collectcd liquida to be safely disposed. The perforated plate may be fabricated from a low température alloy.

[0021] The vapor venting system 110 can be designed such that in the event of a leak, the

System can safely vent the Jeaking vapors without exceeding the design.pressure of the primary enclosure. Cryogénie vapor leaks would be collectcd and safely handled via a venting system on the side or roof of the primary enclosure. Instrumentation to detect the presence of leaking cryogénie vapors could be installed and allow either automatic or manual intervention to safely direct leaking materials to a safe location for disposai.

[0022] Structural support members, not shown in FIG. 1, can be constructed outside of the primary enclosure. The structural support members can be fabricated from a material that docs not expérience cold or brittle cracking, such as stainless steel, a material capable of functioning in a cryogénie environment with an insulating agent applied thereto, or a combination thereof. Insulation barriers, such as, micarta wood, can be used to separate the structural support members from those which are not designed to handle cryogénie températures. [0023] A fîre retardant agent may be applied to the exlerior surface of the primary enclosure depicted in FIG. 1. The fire retardant protects the primary enclosure from cxternal fîres.

[0024] FIG. 2 depicts a primary enclosure defîning an internai volume surrounded by a secondary enclosure. The primary enclosure can function as a container of lhe thermal insulation cupable of containing equipment operating at cryogénie températures. For instance, the primary enclosure can be a cold box. Additionally, the primary enclosure may contain scveral pièces of equipment, such as beat exchunger(s), separator(s) and/or column(s).

[0025] If the primary enclosure is fabricated from a low température alloy, then a secondary enclosure is optionak However, if the primary enclosure is fabricated from a material mcrely capable of functioning as the container of the insulation material in a cryogénie

environment and not designed to operalc al cryogénie températures,.then insulation of that material is necessary along with a secondary enclosurc.

[0026] Referring to FIG. 2, the primary enclosure 300 includes primary walls 302, a primary ceiling 304, a primary floor 306, and a vapor venting System 310. At least a portion of the primary floor 306 forms a slope lo a hydrocarbon outlet 308 to encourage hydrocarbon drainage. A perforated plate 110 is located on top of the of the hydrocurbon outlet 308. The perforated plate prevents the bulk fill insulation within the internai volume from exiting the primary enclosure. A scrcen may cover the perforated plate. The perforated plate can be fabricaled from a low température alloy.

[0027] The secondary enclosure, formed around the primary enclosure, 200 includes secondary walls 202, a secondary ceiling 204 and a secondary floor 206. The secondary enclosure provides addilionai protection against beat leakage. At least a portion of the secondary floor 206 forms a slope.

[0028] The primary enclosure can be fabricaled from a low température alloy, a material capable of functioning in a cryogénie environment with an insulating agent applied thereto, or combinations thereof. For exampie, the walls and ceiling of the primary enclosure can be fabricaled from a material capable of functioning in a cryogénie environment with an insulating agent applied thereto. The secondary floor can be fabricaled from a low température alloy.

[0029] Carbon sleel, for example, is a material capable of functioning in a cryogénie environment. However, carbon steel can expérience cold brittle fracture if exposcd lo cryogénie fluids. Thus, an insulating agent must be applied to carbon steel surface exposed to a cryogénie environment.

[0030] The secondary enclosure can be fabricaled from a low température alloy, a material capable of functioning in a cryogénie environment, or combinations thereof.

[0031] The vapor venting system 310 can be designed such that in the event of a leak, the

System can safely vent the leaking vapors without cxcccding the design pressure of the primary enclosure. Cryogénie vapor leaks would be collected and safely handled via a venting system on the side or roof of the primary enclosure. Instrumentation to detect the presence of leaking cryogénie vapors may be installed lo allow either automatic or manual intervention to safely direct leaking materials to a safe location for disposai.

[0032] Structural support members 400 can bc constructed between the primary and secondary enclosures. The volume between structural support members between the primary and secondary enclosures can be purged with dry aîr. The structural support members can bc fabricated from a material that does not expérience cold or brittle cracking, such as slainless stccl, a material capable of funcüoning in a cryogénie environment with an insulating agent, or a combination thereof. Insulatlon barriers, such as, micartu wood, can be used to separate the structural support members from those which are not résistant to cryogénie materials.

[0033] A fire retardant agent may be applied to the exterior surface of the primury enclosure depictcd in FIG. 2. The fire retardant prolects the primary enclosure from extcrnal tires.

[0034] The advantages of the modified cold boxes arc that they offer an additional layer of safety protection that safcly disposes of potentially flammable materials in the event of a leak inside a cold box. Additionally, if leaking materials outside the cold box cause a Pire to the modified cold boxes protect the equipment inside the cold box from an external fire.

[0035] In closing, it should be noled that the discussion of any reference is not an admission that it is prior art to the présent invention, especially any reference that may hâve a publication date after the priority date of this application. At the same time, each and every claim below is hereby incorporaled into this detailed description or spécification as additional embodiments of the présent invention.

[0036] Allhough the Systems and processes described herein hâve been described in detail, it should be understood thaï various changes, substitutions, and alterations can be made without departing from the spiril and scope of the invention as defined by the following daims. Those skilled in the art may be able to study the preferred embodiments and identify other ways to practice the invention that arc not exuctly as described herein. It is the intent of the invenlors thaï variations and équivalents of the invention are within the scope of the daims while the

The description, abstract and drawings arc not to be used to limit the scope of the invention.

Claims (10)

1. An apparatus comprising:

a. a primary enclosurc, optionally a cold box, defining an internai volume, wherein the primary enclosure comprises primary walls, a primary ceiling, a primary floor, and a vapor venting System, wherein the primary enclosure is fubricated from a low température alloy, optionally wherein the low température alloy is slainless steei or a high nickel steel, wherein al least a portion of the primary floor forms a slope to a hydrocarbon outlet, wherein a perforated plate is located on top of the hydrocarbon outlet, wherein the perforated plate is fubricated from a low température alloy; and

b. a fîre retardant agent applied to the exterior surface of the primary enclosure.

2. The apparatus according to claim 1, wherein the internai volume of the primary enclosure comprises bulk fill insulation, e.g. of perlite, silica aerogel, or any combination thereof.

3. The apparatus according to claim 2, wherein the perforated plate prevents the bulk fill insulation from exiting the apparatus.

4. The apparatus according to claim 1, wherein a screen is on top of the perforated plate.

5 12.

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5 12.

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10 15.

11.

5. An apparatus comprising:

a. a primary enclosure, optionally a cold box, defining an ihternal volume, wherein the primary enclosure comprises primary walls, a primary ceiling, a primary floor, and a vapor venting system, wherein the primary enclosure is fabricatcd from a low température alloy, optionally wherein the low température alloy comprises stainless steel or a high nickel steel, wherein at least a portion of the primary floor forms a slope to a hydrocarbon outlet, wherein a perforated plate is located on top of the slope, wherein the perforated plate is fabricated from a low température alloy;

b. a secondary enclosure surrounding the primary enclosure defining a second internai volume, wherein the secondary enclosure comprises secondary walls, a secondary ceiling and a secondary floor, optionally wherein the secondary enclosure is fabricated from a low température alloy, such as stainless steel or high nickel steel, a material capable of functioning in a cryogénie environment, such as carbon steel, or combinations thereof; and

1U

c. a firc retardant agent applied lo the exterior surface of the secondary enclosure and, optionally, to the exterior surface of the primary enclosure.

6. The apparatus according to claim 5, wherein the internai volume of the primary enclosure comprises a bulk fill insulation, such as pcrlile, silica aerogcl, or uny combination thereof, optionally wherein the perforuted plate prevents the perlite from exiling the apparatus.

7. An apparatus comprising:

a. a primary enclosure, optionally a cold box, defining an internai volume, wherein the primary enclosure comprises primary walls, a primary ceiling, a primary floor, and a vapor venting system, wherein at least a portion of the primary floor forms a slope for hydrocarbon drainage, wherein a perforated plate is located on top of the slope, wherein the perforated plate is fabricated from a low température alloy;

b. a secondary enclosure surrounding the primary enclosure defining a second internai volume, wherein the secondary enclosure comprises secondary walls, a secondary ceiling and a secondary floor, optionally wherein the primary walls are fabricated from a low température alloy, such as stainleàs steel or a high nickel steel, a material capable of operaling in a cryogénie environment, such as carbon steel, with an insulating ugenl applied to the primary walls, or a combination thereof; and

c. a fire retardant agent applied lo the exterior surface of the secondary enclosure.

8. The apparatus according to claim 7, wherein the primary ceiling is fabricated from a low température alloy, such as staînless steel or a high nickel steel, a material capable of operaling in a cryogénie environment, such as carbon steel, with an insulating agent applied the ceiling, or a combination thereof.

9. The apparatus according to claim 7, wherein the secondary walls are fabricated from a low température alloy, such as stainless steel or a high nickel steel, a material capable of operaling in u cryogénie environment, such as carbon steel, with an insulating agent applied the secondary walls, or a combination thereof.

10. The apparatus according to claim 7, wherein the secondary ceiling is fabricated from a low température alloy, such as stainless steel or a high nickel steel, a material capable of il

11.

10 15.

opcrating in a cryogénie environment, such as carbon steel, with an insulating agent applied the secondary ceiling, or a combination thereof.

The appuratus according to claim 7, wherein the internai volume of lhe primary enclosure comprises pcrlile.

The apparatus according to claim 11, wherein lhe perforated plate prevents the perlite from exiling the apparatus.

The apparatus according to claim 7, wherein lhe fire retardant* agent is applied to the exterior surface of the secondary enclosure.

The apparatus according to daims 5 or 7, wherein lhe second internai volume comprises structural support members.

The apparatus according to daims 1, 5 or 7, wherein lhe apparatus is ulilized in onshore facilities or, alternativeiy, offshore facilitics.