Internally cooled pressure containment system

Abstract

An internally cooled pressure vessel includes a high pressure cylinder having an inner shell, and a shrink-fit, floating liner. The movement of the liner is restrained by the axial friction force between the liner and the shell. The liner is removable and has cooling grooves that can be cleaned and inspected in site. The end load is restrained by a tie rod frame, including tie rods and end flanges that are positioned at both ends of the cylinder. Pressure is introduced through separate top and bottom manifolds. To cool the vessel, water is pumped into the bottom manifold, travels through the cooling grooves, and flows out the top manifold.

Description

[0001] This patent application claims priority to U.S. Provisional patent application Ser. No. 60/213,971 filed on Jun. 23, 2000.

FIELD OF THE INVENTION

[0002] The present invention relates to an internally cooled pressure vessel for use in hot isostatic pressing, and particularly relates to an internally cooled pressure vessel to solidify powders and heal cracks and voids in castings.

BACKGROUND OF THE INVENTION

[0003] A pressure vessel may include a cylinder, as well as a closure structure to restrain the end load. The closure structure can be constructed as a threaded end closure or a frame of various designs. Such frame designs include yoke or plate frames; wire wrapped frames and tie rod frames. The cylinder of the pressure vessel can be of a monowall or a multiple wall construction. When a pressure vessel is externally cooled, a temperature gradient is introduced which can generate stress on the outside diameter of the vessel, leading to fatigue and cracking. Larger, high-pressure vessels are particularly susceptible to thermally induced stresses since they have thicker walls. Due to the nature of heat transfer, a given heat flux (watts per unit area) generates a larger temperature gradient across a thicker wall. This, in turn, induces a higher stress at the outer diameter of the wall. This phenomenon increases fatigue and reduces the life of these pressure vessels and may contribute to failures in the field. Pressure vessels with internal cooling mechanisms are known in the art. However, these mechanisms are usually employed with penetration of the shell of the vessel. Penetrations in the shell of the vessel are undesirable for a number of reasons. Pressure vessels known in the art, such as wire wrapped vessels do not lend themselves to complete inspection, visually, ultrasonically, or by magnetic particle inspection.

SUMMARY OF THE INVENTION

[0004] In accordance with the present invention, the pressure vessel includes a top end flange contacting a top manifold, a bottom end flange contacting a bottom manifold, and a high-pressure cylinder positioned between the top manifold and end flange assembly and the bottom manifold and end flange assembly. The top manifold is in contact with one end of the cylinder and the bottom manifold is in contact with the other end of the cylinder. The top end flange covers the top manifold and the bottom end flange covers the bottom manifold. Tie rods are placed into corresponding tie rod holes disposed in the top and bottom flanges. The tie rods and flanges effect closure of opposite ends of the high-pressure cylinder.

[0005] The high-pressure cylinder includes an inner liner and outer shell. Cooling grooves are formed in the exterior side of the liner or, alternatively, the grooves are formed in the interior side of the inner shell. Water is pumped into the bottom manifold, travels up through the grooves and exits through the top manifold.

[0006] The liner is held in place within the cylinder by a slight interference between the larger outside diameter of the liner and the smaller inside diameter of the shell. The liner is not held in place by any other mechanism. To install the liner within the cylinder, the shell is heated. After the liner is installed, the shell is then cooled. The liner is a floating liner, as it is not fixedly attached to any other component of the vessel. The liner can be removed by heating the shell allowing the liner to drop out from the cylinder.

[0007] In use, as the temperature of the liner increases, the water travels through the cooling grooves in the liner to moderate the temperature of the shell. By moderating the temperature of the shell, the axial forces on the end of the flanges are reduced and in turn the stresses on the tie rods are thereby reduced.

[0008] A removable flange engages the lower manifold. The lower manifold engages the lower end flange. A threaded bottom closure engages the lower end flange. When the bottom closure is removed, access to the liner is achieved. When the removable flange on the lower manifold is then removed, the cooling grooves can be accessed and inspected. Moreover, a high-pressure water-blasting lance can be inserted into the cooling grooves and any fouling can be removed therefrom. In addition, the liner can be removed for cleaning by applying modest heat to the outside diameter of the shell.

[0009] Given that the liner floats within the cylinder, it exerts only minimal axial force on the end flanges and tie rods. This is so, even though at elevated temperatures, the liner grows axially. The shrink-fitted liner is sized to be held in place or restrained by the axial friction force between the liner and the shell at the liner's upper end. As the liner grows axially, it grows downward into a space defined by the removable flange, liner inner, bottom manifold, and bottom closure. Thus, the liner does not come in contact with the lower manifold reducing pressure on the bottom end flange and tie rods.

[0010] The bottom closure includes a head and a threaded portion. The threaded portion can be fully threaded or, in the alternative, the threads can be interrupted. If interrupted, a fraction of a full turn of the head will permit the removal of the bottom closure from the lower end flange.

[0011] Under load, the end flanges will deform or bend. Spherical washers are utilized to prevent the tie rods from bending when the end flange deforms under load. By preloading the tie rods, which restrain the end load, cyclical stress on such parts is reduced, thereby extending their life and reducing fatigue.

[0012] Accordingly, it is an object of the present invention to provide an internally cooled pressure vessel, which is not susceptible to the formation of a temperature gradient across the outer wall of the cylinder.

[0013] It is an additional object of the present invention to provide a pressure vessel that accomplishes internal cooling of the shell without penetrations to the shell.

[0014] It is a further object of the invention to provide a pressure vessel that permits inspection, by visual, ultrasonic and magnetic particle means, including the cooling grooves.

[0015] In addition, it is an object of the invention to provide a pressure vessel with a floating liner that can be removed and inspected.

[0016] It is also an additional object to provide a pressure vessel that introduces pressure through a separate manifold.

[0017] Further it is an object to provide a pressure vessel that avoid stress concentrations due to pressure ports in the shell, closure, and end flanges.

[0018] Lastly, it is an object of the present invention to provide a pressure vessel that removes the stress concentration, which occurs at the root of the first thread in a threaded closure.

[0019] Additional objects, characteristics and advantages of the invention will emerge from the following description given by way of non-limiting illustrative example with reference to the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 is a perspective view, with some cut-away portions, of the preferred embodiment of the subject invention.

[0021] FIG. 2 is a cross-sectional view of the preferred embodiment of the subject invention.

[0022] FIG. 3a is an enlarged view of the assembled flanges and lower manifold, the area circled in FIG. 2, of the preferred embodiment of the subject invention.

[0023] FIG. 3b is an enlarged view of another section of the assembled top manifold of the preferred embodiment of the subject invention.

[0024] FIG. 4a is a side view of the bottom flange of the preferred embodiment of the subject invention.

[0025] FIG. 4b is a side view of the bottom closure of the preferred embodiment of the subject invention, showing the relationship of the bottom closure to the bottom flange.

[0026] FIG. 5a is a side cross-sectional view of the bottom flange of the preferred embodiment of the subject invention, while disengaged from the bottom closure.

[0027] FIG. 5b is a side cross-sectional view of the bottom flange of the preferred embodiment of the subject invention, while engaged to the bottom closure.

[0028] FIG. 5c is a side view of the bottom flange of the preferred embodiment of the subject invention, with bottom manifold attached thereto.

[0029] FIG. 6a is a side view of the removable flange of the preferred embodiment of the subject invention.

[0030] FIG. 6b is a side view of a disassembled removable flange and lower manifold of the preferred embodiment of the subject invention.

[0031] FIG. 6c is a cross-section view of the assembled removable flange and lower manifold of the preferred embodiment of the subject invention.

[0032] FIG. 7a is a perspective view of the bottom manifold of the preferred embodiment of the subject invention.

[0033] FIG. 7b is cross-sectional side view of the bottom manifold of the preferred embodiment of the subject invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0034] A pressure vessel 10 comprising a preferred embodiment of the present invention is shown in FIGS. 1 through 7. The pressure vessel 10 includes high pressure cylinder 11. Cylinder 11 includes shell 20. Pressure vessel 10 also includes top end flange 14 and bottom end flange 26, as well as top end manifold 36 and bottom manifold 24. Cylinder 11 is position between top flange 14 and bottom flange 26.

[0035] As shown in FIG. 1 bottom manifold 24 has ports 30. Top manifold 36 (not shown) will have port As shown in FIG. 4, bottom end flange 26 possess recess 33 for mating with top manifold 36 and bottom manifold 24, respectively. As seen in FIG. 1, one end of cylinder 11 is in contact with top manifold 36, while the other end of cylinder 11 is in contact with bottom manifold 24.

[0036] Tie rods 34 are placed in corresponding tie rod holes 12 disposed in top end flange 14 and bottom end flange 26. Tie rods 34 and end flanges 14 and 26, along with bottom closure 40 effect closure of cylinder 11.

[0037] Disposed within cylinder 11 is liner 16. Cooling grooves 18 are most preferably formed in liner 16. As one of ordinary skill in the art will readily appreciate, cooling grooves 18 can be axially machined in shell 20, or by separate pieced lengthwise strips, for example, installed between liner 16 and shell 20. Moreover, cooling grooves 18 need not be axial. Alternatively, cooling grooves 18 can be helical, which would necessitate the use of a flexible borescope for inspection, and a flexible water blast lance for cleaning.

[0038] Water is pumped into bottom manifold 24, through one of ports 30 and travels through cooling grooves 18 and exits through one of ports 38 in top manifold 36.

[0039] Liner 16 is held in place within cylinder 11 in view of a slight interference between the larger outside diameter of liner 16 and the smaller inside diameter of shell 20. When shell 20 is heated, liner 16 can be installed within cylinder 11. Shell 20 is then cooled. As such, liner 16 is said to be shrink-fit within cylinder 11. In use, as the temperature of liner 16 increases, the water traveling through cooling grooves 18 moderates the temperature of shell 20. By moderating the temperature of shell 20, the axial forces on end flanges 14 and 26, and, in turn, tie rods 34, are minimized. The stresses on tie rods 34 are thereby reduced. Liner 16 floats within cylinder 11. As such, liner 16 cannot exert any additional axial force on end flanges 14 and 26 and tie rods 34. This is so even though at elevated temperatures, liner 16 grows axially. Liner 16 is sized to be held in place or restrained by the axial friction force between liner 16 and shell 20 at the upper end of liner 16. As liner 16 grows axially, it grows toward, but does not come in contact with lower manifold 24, in view of space 22, as shown in FIG. 3.

[0040] Bottom closure 40, having threads 32, threadably engages lower end flange 26. When bottom closure 40 is removed, access to liner 16, as well as cooling grooves 18, is achieved. As shown in FIG. 3, when removable flange 28 is removed from lower manifold 24, cooling grooves 18 can be inspected. A high pressure water blasting lance can be inserting into each of grooves 18 and any fouling can be removed therefrom. In addition, liner 16 can be removed from cylinder 11 for cleaning by applying modest heat to the outside diameter of cylinder 11. Bottom closure 40 can be fully threaded, as shown in FIG. 4B, or, in the alternative, threads 31 can be interrupted. If interrupted, a fraction of a full turn of closure 32 will permit the removal of bottom closure 40 from lower end flange 26.

[0041] Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modifications and variations may be made without departing from what is regarded as the subject matter of the invention.

Claims

1. A pressure vessel comprising:

a pressure containment with a top end and a bottom end and side walls, forming a pressure chamber, said top end and said bottom end being open; said containment having a shell and a liner,

a top manifold having a top section, a bottom section, and a side wall, said side wall having a plurality of ports, said bottom section contacting said top end of said shell,

a bottom manifold having a top section, a bottom section, and a side wall, said side wall having a plurality of ports, said top section contacting said bottom end of said shell,

a retainer contacting said bottom end of said liner,

a retainer spring supporting said retainer so as to maintain a space between the liner and said bottom manifold,

a top end flange contacting said top end also contacting said top manifold at top section of said containment, and

a bottom end flange having a recess for mating with said lower manifold at the bottom section of said manifold,

said end flanges having portions defining a plurality of holes, and

a plurality of tie rods with each one of said tie rods residing simultaneously within one of said top flange holes and one of said bottom flange holes.

2. A pressure vessel according to claim 1 in which a removable flange is located at the top of said lower manifold of the said pressure chamber of said containment.

3. A pressure vessel according to claim 2 in which said removable flange is held in place by at least one removable screw.

4. A pressure vessel according to claim 1 in which the said liner is a floating liner held in place by an interference between the larger outside diameter of the said liner and the smaller inside diameter of said shell.

5. A pressure vessel according to claim 4 in which spacers are placed longitudinally between said liner and said shell.

6. A pressure vessel according to claim 4 in which grooves are formed into the interior surface of said shell.

7. A pressure vessel according to claim 4 in which grooves are formed into the exterior surface of said liner.

8. A pressure vessel according to claim 7 in which said grooves are aligned in an axial direction.

9. A pressure vessel according to claim 7 in which said grooves are aligned in a helical direction.

10. A pressure vessel comprising:

a pressure containment with a top end and a bottom end and side walls, forming a pressure chamber, said top end and said bottom end being open; said containment having an shell and a liner,

a top manifold having a top section, a bottom section, and a side wall, said side wall having a plurality of ports, said bottom section contacting said top end of said shell,

a bottom manifold having a top section, a bottom section, and a side wall, said side wall having a plurality of ports, said top section contacting said bottom end of said shell,

a retainer contacting said bottom end of said liner,

a retainer spring supporting said retainer so as to maintain a space between the liner and said bottom manifold,

a top end flange contacting said top end and having a recess for mating with said top manifold said top end flange defining a plurality of holes,

a bottom end flange substantially annular having a recess for mating with lower manifold said bottom flange defining a plurality of holes

a bottom closure engaging said bottom end flange, and

a plurality of tie rods with each one of said tie rods residing simultaneously within one of said top end flange holes and one of said bottom flange holes, at least one spherical washer at the each end of said each of said tie rods.

11. A pressure vessel according to claim 10 in which the said liner is a floating liner held in place by a interference between the larger outside diameter of the said liner and the smaller inside diameter of said shell.

12. A pressure vessel according to claim 11 wherein a removable flange is located at the top of said lower manifold of said containment.

13. A pressure vessel according to claim 12 in which said removable flange is held in place by at least one removable screw.

14. A pressure vessel according to claim 12 wherein said bottom closure is fully threaded.

15. A pressure vessel according to claim 12 wherein said bottom closure is interruptedly threaded.

16. A pressure vessel according to claim 15 in which spacers are placed longitudinally between said liner and said shell.

17. A pressure vessel according to claim 15 in which grooves are formed into the inner surface of said shell.

18. A pressure vessel according to claim 15 in which grooves are formed into the exterior surface of said liner.

19. A pressure vessel according to claim 18 in which said grooves are aligned in an axial direction.

20. A pressure vessel according to claim 18 in which said grooves are aligned in a helical direction.

21. A method of inspecting and cleaning a pressure vessel said vessel comprising:

a pressure containment with a top end and a bottom end and side walls, forming a pressure chamber, said top end and said bottom end being open; said containment having a shell and a liner wherein said liner is a floating liner held in place by a interference between the larger outside diameter of the said liner and the smaller inside diameter of said shell.

wherein grooves are formed into said liner,

a top manifold having a top section, a bottom section, and a side wall, said side wall having a plurality of ports, said bottom section contacting said top end,

a bottom manifold having a top section, a bottom section, and a side wall, said side wall having a plurality of ports, said bottom section contacting said bottom end,

a removable flange located the top of said lower manifold,

a retainer contacting said bottom end of said liner,

a retainer spring supporting said retainer so as to maintain a space between the liner and said bottom manifold,

a top end flange contacting said top end and having a recess for mating with said top manifold at top section of said containment said top end flange defining a plurality of holes,

a bottom end flange substantially annular having a recess for mating said bottom manifold at the bottom end of said containment, said bottom flange defining a plurality of holes

a bottom closure engaging said bottom end flange, and

a plurality of tie rods with each one of said tie rods residing simultaneously within one of said top end flange holes and one of said bottom flange holes, at least one spherical washer at the each end of said each of said tie rods, wherein said method comprises:

removing said bottom closure,

removing said bottom manifold,

removing said removable flange,

inserting an inspection device into said grooves, and

inserting a cleaning device into said grooves.

22. The method of inspection and cleaning of claim 21 further comprising:

heating said containment,

dropping said liner from within said shell and

inspecting and cleaning said liner and said containment.