DE8816612U1 - Horizontal pressure vessel for the storage of liquefied gases - Google Patents

Description

Horizontal pressure vessel for the storage of liquefied gases

The invention relates to a horizontal pressure vessel for the storage of liquid gases, such as ammonia or the like, consisting of an elongated closed inner vessel with a peripheral wall and two end walls, which is supported in a longer outer vessel with a peripheral wall and two end walls in such a way that at least at one end a walkable cavity is formed between the one end wall of the outer vessel and the adjacent end wall of the inner vessel, with a closable manhole being provided on the top of the outer vessel and of several line connections on the inner vessel, to which line ducts leading to the outside are assigned.

In power plants, gaseous nitrogen is used to denitrify flue gases by catalytic reduction of nitrogen oxide.

Telephone (02 21) 131O<41

Fax (0221)131297 (0221) &Pgr;&Lgr;881 Telegram Dompatent Ki

SaI Oppenheimjf 4Ce ₁ KuIn(BLZSrCzSOaOO)KtO No. 10760 OejKche Bank AG. Cologne (BLZ 370 70O60) Account No. 1165018 Postgiro Cologne (BLZ 37010050) Account No. 654-5OO

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In order to keep ammonia in stock for this purpose, small tank farms have been built that contain liquefied ammonia that is converted into a gaseous state by evaporation. The safety regulations for tank farms for pressure-liquefied ammonia require a high level of protection against the formation of leaks due to stress corrosion cracking or external influences in order to avoid accident-related releases of ammonia. An important safety factor is the ability to inspect the components, particularly the welds and penetrations, by visual inspection from all sides. However, this is not sufficiently feasible in all places with the known pressure vessels, so that leak detection or prevention is not yet reliable enough.

Cylindrical or spherical single-walled containers are placed above ground in large-area collecting trays and the liquid is removed through a nozzle in the bottom of the container. A single-walled container is not suitable for buried embedding in the ground, which is good for protection against external influences, and double-walled pressure vessels have been designed for this purpose. A double-walled pressure vessel with an open dome shaft is known, which consists of an elongated, closed inner container and an outer container surrounding it, forming a uniform space between them.

3C at the two ends of the inner and outer container, a large opening is formed in the peripheral wall of the outer container, through which the lower end of a dome shaft is inserted until its lower edge rests against the peripheral wall of the inner container. The

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The dome shaft is welded to the edge of the opening in the outer container as well as to the inner container all around. This means that the double-walled container is single-walled over the extent of the dome shaft. This design already limits the possibility of inspecting the welded joints between the dome shaft and the two containers when the pressure vessel is in place, because the welded joints can only be inspected from the inside of the dome shaft and not in the closed space between the outer and inner containers. Inspection and maintenance work are also made more difficult by the inaccessibility of the space between the inner and outer containers. Since mechanical stresses cannot be avoided when storing ammonia, stress concentrations arise on the dome shaft, which increase the disadvantage of inadequate inspectability of the weld point.

To remedy the described deficiency of a double-walled pressure vessel with a single-walled dome shaft, a completely double-walled pressure vessel of the type mentioned at the beginning has been proposed, which is intended for above-ground or underground storage ("Technical Communications, 80th year, issue 9, November/December 1987, pages 633 to 635). In this pressure vessel, all line connections on the inner vessel and line penetrations on the outer vessel are formed in the surfaces of the two end walls of the inner vessel and the outer vessel that delimit the cavity. This means that the protective earth covering in the area of the end face must be missing so that the line penetrations can be checked from the outside and the connected lines can be accessed outside the pressure vessel. The construction of a shaft at this end of the pressure vessel is planned.

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ter, which requires special safety precautions against unauthorized intervention and external influences. In addition, the frontal exit of the pipes from the pressure vessel, which is provided at any point, does not meet the safety standard because leaks at the pipe connections of the inner vessel below the liquid level result in liquid ammonia immediately escaping into the outer vessel and there is a risk that this will leak out through leaks from pipe penetrations of the outer vessel at the same level. Such coupled damage to associated pipe connections and pipe penetrations cannot be ruled out as a malfunction because the pipes connecting them, even if they are flexible, can generate mechanical stress at the welds as a result of temperature fluctuations, which can lead to damage at both ends of the pipes. The cavity between the outer vessel and the inner vessel front wall is accessible through a manhole in the outer vessel.

The invention is based on the task of improving a completely double-walled horizontal pressure vessel of the type mentioned at the beginning so that it meets high safety requirements in terms of construction and enables easier, unrestricted visual inspection.

This object is achieved according to the invention in that the line connections of the inner container are arranged in the upper apex zone of its peripheral wall and in that in the peripheral wall of the outer container at its cavity-side end part an upwardly projecting^ externally

closed dome is formed, which is provided with a manhole and equipped with cable ducts.

The undetected formation of larger leaks is practically impossible with this pressure vessel because the line connections can be arranged on the peripheral wall of the inner vessel in a clearly accessible manner so that the operating personnel can easily inspect and check them from all sides. Since the Dom nici L is connected to the inner vessel, weld seams can be checked non-destructively from the outside and inside by visual inspection because there are no closed chambers between the inner vessel and the outer vessel and the interior of the outer vessel and the dome in the area of interest is freely accessible. Stress concentrations do not occur on the dome because it is not connected to the inner vessel, which is subject to thermal expansion. Stress corrosion cracking during storage of pressure-liquefied ammonia is therefore prevented. The dome, which is closed on the outside, continues the peripheral wall of the outer vessel in a closed manner, forming an outward curvature, so that a perfect double-walled pressure vessel is present, which can be covered on all sides by earth, so that it is protected from environmental influences as a whole and only the dome with the manhole remains free of earth, which is not dangerous because it is located above the liquid level and because leaks in this area, which is completely independent of the inner vessel, are not critical. The pipe connections of the inner vessel are located exclusively above the liquid level, i.e. they open into the gas zone of the inner vessel and leaks at their weld seams only let gas in and not

Liquid can leak out. The concentration of the pipe penetrations in this external area of the tank is advantageous in terms of safety. This also makes the production of the tank cheaper, because

OS only the dome needs to be equipped with cable ducts and such equipment work on the outer vessel is not required. All butt welds and nozzle inlets/weldings can be fully load-bearing and counter-welded from the inside. All welds are accessible and testable for non-destructive testing during production so that clear non-destructive test results are achieved. The pressure vessel meets high safety standards.

In a preferred embodiment of the invention, one end of the inner container extends axially into the area of the outer container occupied by the dome and the line connections are provided essentially in the peripheral wall of this end of the inner container. This feature means that when entering the outer container through the manhole in the dome, both the cavity outside the inner container and the line connections provided on its upper side in the area of the dome are easily accessible. The line connections can be provided in several rows next to one another. The approximately vertical pipes between the line connections of the inner container and the line openings in the dome are relatively short and can be arranged in such a way that their clarity is maintained and they can be inspected without restriction. In addition, the vertical course of the pipes between the inner container and the dome provides improved protection against the line connections or line feedthroughs being torn out.

g.sn can be achieved as a result of thermal expansion of the inner container, because the pipes are not subject to axial stress and can follow the movements of the inner container if they are designed to be flexible and/or by installing compensators.

In one embodiment of the invention, the dome is designed as a tower structure with side walls and top walls, so that a closed tower is created that is open at the bottom and leads into the interior of the outer container. The cable ducts are arranged in the side walls and/or the top wall of the dome. In any case, they are easily accessible from both sides for inspection and repair. The manhole is preferably provided eccentrically in the upper wall of the dome, so that the part of the top wall free from the manhole is available for the installation of cable ducts. This installation also has the advantage that the manhole is offset near the cavity between the end walls of the outer container and the inner container, so that when a ladder is lowered, the cavity can be reached directly and the inner container does not form an obstacle.

Since the pressure vessel can be covered with earth on all sides, but the dome should be kept free of earth, the dome is preferably surrounded by an open shaft pipe, which can be closed if necessary. A walk-on grating is arranged in the space between the side wall of the dome and the shaft pipe in the lower part of the same. The operating personnel can easily carry out all inspections from the outside by walking around the dome, without needing any special tools and without causing any inconvenience.

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- 8 abilites to be accepted.

A further advantageous embodiment of the invention is characterized in claim 6. The elongated eccentric upper extension of the peripheral wall of the outer container forms a bulge of the circular cylindrical outer container to one side, so that in this area the inner container is far away from the peripheral wall of the outer container and from its front wall.

The cavity formed above and at the end of the inner container is easily accessible for inspection and maintenance work through the manhole in the outer container. On both containers, in the area of the gas zone of the inner container, there is enough space to accommodate the line feedthroughs of the outer container and the line connections of the inner container, each next to a manhole. Since the outer container and the inner container each have an additional manhole at the end facing away from the dome in the apex zone, the accessibility of the interior of the inner container is improved and the work of the fitters and inspectors is made easier.

The elongated design of the dome allows the cable ducts and cable connections to be located vertically above one another and arranged in several parallel rows. This results in a clear cable routing, which is convenient both for installation and maintenance work.

The extension of the outer container is preferably formed from a ring section of larger diameter, which is connected via an inclined wall to the peripheral wall of smaller diameter 35

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diameter. The inclined wall bridges the step between the two circular cylinders of different diameters. The two ends of the outer container are closed by cap-like end walls, which are adapted to the respective container diameter.

The double-walled container according to the invention is not only suitable for the storage of ammonia, but for all water-polluting liquids for which a protective space is required to contain the liquid in the event of a rupture of the storage container. In such cases, the entire construction can also be made of materials other than steel, e.g.

made of plastics or composite materials, such as steel-plastic.

In the drawing, embodiments of the invention are shown schematically. They show: 20

Fig. 1 a longitudinal section through a first embodiment of a horizontal pressure vessel,

Fig. 2 is a cross-section along the line II-II in Figure 1,

Fig. 3 is a plan view in the direction of arrow III in Figure 1,

Fig. 4 shows a longitudinal section through a second embodiment of a pressure vessel, Figs. 5 and 6 show cross sections along the lines V-V and VI-VI in Fig. 4.

The pressure vessel 10 for storing pressure-liquefied ammonia, for example in power plants, consists essentially of a pressure-resistant outer vessel 11, e.g. made of steel, and a shorter pressure-resistant inner vessel.

container 12, e.g. made of steel. The outer container 11 and the inner container 12 each have a cylindrical peripheral wall 13 and 14 respectively and are closed at both ends by outwardly curved symmetrical end walls 15, 16 and 17, 18 respectively. The outer container 11 and the inner container 12 are assembled from welded ring segments. To assemble the pressure vessel 10, the finished, stress-relieved inner vessel 12 is pushed into the one open end of the outer vessel 11 on circumferential ring stiffeners 20 and longitudinally extending skids 21 into the outer vessel 11 until the rear end of the peripheral wall 14 rests on a fixed point bearing 22, which ensures that longitudinal movements of the inner vessel 12 can be carried out in a controlled manner in a specified direction as a result of different operating temperatures and pressures. Completion of the inner vessel 12 also includes welding in a block flange 23 with a cover 25 and welding in a large number of line connections 24 in the upper apex zone of the inner vessel 12, which provide access to the interior of the inner vessel 12. All weld seams are fully load-bearing and counter-welded from the inside.

Since the inner container 12 has a smaller diameter than the outer container 11 and is shorter than the latter, an enlarged cavity 29 is created between the end walls 16 and 18 when an approximately uniform gap 26 is left between the end walls 15 and 17 and the peripheral walls 13 and 14. This cavity 29 is accessible through a dome 30 which is located at one end of the outer container 11 in its upper apex zone. The dome 30 is designed as a circular cylindrical tower structure made of sheet steel, which consists of a side wall 32 and an outwardly curved upper wall 33.

wall 31, which are welded together. A manhole 33 is provided eccentrically in the circular upper wall 31, the upstanding support 34 of which can be closed by a cover 35. The lower edge 32a of the side wall 32 of the dome 30 is welded on both sides into an opening 36 in the upper apex area of the peripheral wall 13 of the outer container 11. The dome 30 is not connected to the inner container 12. It forms a closed tower-like bulge in the peripheral wall 13 of the outer container 11, with the result that the pressure vessel 10 is double-walled overall and there are no insulation problems at any point. The inner container 12 projects with its end wall 18 beyond the vertical center plane of the drain 30. However, there remains a sufficiently wide passage between dome 30 and cavity 29 through which the operating personnel can reach cavity 29 via a conductor 37.

Line ducts 40 are welded into the side wall 32 and/or the top wall 31 of the dome 30 by means of internal and external welds. The line connections 24 and the line ducts 4G are connected to one another via flexible pipes 41 within the dome 30 and further lines are connected to the outer nozzles of the line ducts 40. At least one line connection 24 can be provided for connection to a riser pipe 42 which extends to the bottom of the inner container 12. Another tubular line duct welded into the top wall 31 via a compensator 43 carries a display instrument 44 which is connected to a float 45 within the inner container 12 and displays the liquid level.

When the pipes 41 are connected, the

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Front wall 16 is sealed with the outer container 11. Then the first joint pressure test of the inner container 12 and the outer container 11 takes place. Due to the geometrically clear circular construction of the dome 30 and its connection only to the outer container 11, neither faults nor other stress concentrations occur and stress corrosion cracking is counteracted. The inner container 12 is characterized by optimal protection and a maximum level of safety because all line connections 24 are cut in the entire area, i.e. above the level A of the aeronautical liquid B and are located entirely within the closed outer container 11, which forms a second containment of the tank-in-tank construction.

The calculation and dimensioning of the cylindrical vessels 11 and 12, the line connections 24 and line ducts 40 as well as other components can be carried out using conventional and known methods of the TRB/AD, TRD regulations. Stress analyses and finite element investigations as with the known double-walled pressure vessel with a single-walled dome shaft are not required. All butt welds and support recesses can be fully load-bearing and counter-welded from the inside. One-sided welded closing seams are not required. All welds are accessible and testable for non-destructive testing during production and at any time later, so that the pressure vessel 10 meets high safety standards. Specified intervals for repeat tests of the welds of the pressure vessel 10 create a high level of accident prevention. Damage to the vessel due to stress corrosion cracking or manufacturing errors is almost impossible. The container is very easily accessible from inside and outside at any time to assess its functional reliability and offers

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- 13 thus increased protection.

The side wall 32 of the dome 30 is surrounded on the outside by a walkable horizontal grating 46, which rests on a support 47 on the side wall 32 and a support 48 on the inside of a shaft pipe 49. The shaft pipe 49 is made of sheet metal and can be open at the top. It is welded onto the Au-P.DnhehäH-pr 11 and keeps the area d^=; dome 30 free of soil 50, which otherwise covers the pressure vessel 10 on all sides. The grating 46 allows unrestricted inspection of the external welds in the area of the dome 30. The internal welds are also easily accessible after entering through the manhole 33, both for inspection and for repair.

The block flange 23, which provides access to the interior of the inner container 12, is located below a shaft 51, the lower edge 52 of which is welded to the peripheral wall 13 of the outer container 11 at an opening 53. A cover 54 can be pivoted away from the upper access opening of the shaft 51 via a pivoting device 55. Since the shaft 51, like the dome 30, is not connected to the inner container 12, it does not interrupt the double wall of the pressure vessel 10 and does not prevent thermal expansion of the inner container as a result of temperature fluctuations of the liquid ammonia.

In the example according to Figures 4 to 6, which illustrates another advantageous embodiment of a horizontal pressure vessel 100, identical parts with the same reference numbers are provided with the example of Figures 1 to 3.

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The pressure vessel 100 consists of a pressure-resistant outer vessel 111, e.g. made of steel, and a pressure-resistant inner vessel 112, which is also made of steel, e.g. The inner vessel 112 is assembled and stored in the same way as described for the first example. In addition, the inner vessel 112 rests on bearing saddles 121, which are arranged in the lower peripheral area of the outer vessel 111. The diameter and length of the inner vessel 112 are smaller than those of the outer vessel 111. The inner vessel 112 has a circular cylindrical peripheral wall IM and is closed at its ends by welded-on, outwardly curved end walls 117, 118. Outwardly curved end walls 115, 116 also close the outer vessel 111, the design of which is explained in detail below. With regard to the construction and assembly of the inner container 112 in the outer container 111, reference is made to the corresponding explanations for the previous example. Completion of the inner container 112 also includes welding the block flange 23 with cover 25 to a manhole 119 at the end of the end wall 117 and welding a large number of line connections 124 in the upper apex zone of the inner container 112 at the other end. The line connections 124 are preferably arranged in several parallel rows, both in the transverse direction and in the longitudinal direction of the pressure vessel 100. All weld seams are fully load-bearing and counter-welded from the inside.

The diameter of the circular cylindrical outer container 111 is reduced by a 35 mm

uniform gap 126 larger than the outer diameter of the inner container 112, which is arranged coaxially in this section. In the upper apex zone of the peripheral wall 113 of this section, a shaft 51 is welded into a circular manhole 153 above the entrance 119 closed by the cover 25, the upper opening of which is closed by a cover 54 on a pivoting device 55.

The peripheral wall 113a has a considerably larger diameter on the section of the other half of the outer container 111 and the end wall 116 is correspondingly larger than the end wall 115. The peripheral wall 113a is part of a ring segment of larger diameter which is welded to the peripheral wall 113 of the other section of the outer container 111 via a bevel wall 146 in such a way that an eccentric upper extension is produced on the outer container 111, which forms an elongated dome 130. The peripheral wall 113a surrounds the inner container 112 in its lower region with the distance of the intermediate space 126, while the dome 130 creates a large free space 127 above its upper region. As a result of the increased distance between the two end walls 116 and 118, a walk-in cavity 129 is created here. This can be reached via a hookable ladder (not shown) that can be attached to a manhole 133 that is provided in the upper apex zone of the dome 130 near the inclined wall 146 and can be closed with a cover 135. The manhole 133 has a nozzle 132, the lower edge of which is welded to the edge of an opening 136 in the upper apex area of the dome 130.

Below the manhole 133, in the apex zone of the inner container 112, a second entrance 120 is provided.

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which is surrounded by an inwardly projecting block flange and closed by a cover 25. Ladders 121, 122 are permanently anchored in the two entrances 119 and 120.

In the apex zone of the dome 130, line ducts 140 are welded in by means of internal and external welds. The line connections 124 and the line ducts 140 are connected to one another via flexible pipes 141 within the crescent-shaped free space 127, and further lines are connected to the outer nozzles of the line ducts 140. The inner container 112 can be equipped with a riser pipe and the display instruments can be installed in a similar way to that explained in the example of Figures 1 to 3. The line connections 124 and the line ducts 140 are preferably arranged vertically one above the other in several parallel rows. They occupy the apex zones of the peripheral walls 114 of the inner container 112 and 113a of the dome 130 in the longitudinal section between manhole 133 or entrance 120 and the front wall 116 or 118. In this way, the fixed point 22 comes further outwards and can be reached from the inspection room 129 after the inner container 112 has been pushed in. At the same time, the fixed point 22 should always be located directly under the pipe bundle 141 so that longitudinal displacements of the inner container 112 have only a minor effect or no effect at all on the pipe connections.

The earth covering 150 with a thickness of about 1.00 m is laid over the inclined wall 146; only the horizontal apex area of the dome 130 is exposed above ground. All other peripheral wall parts of the outer container 111 are sunk into the ground to provide protection.

Claims (9)

!■111· * · 111 ·»■ » &diams; - 17 PROTECTION CLAIMS 1. Horizontal pressure vessel (10) for storing liquefied gases, such as ammonia or the like, consisting of an elongated closed inner vessel (12) with a peripheral wall (14) and two end walls (17, 18), which is supported in a longer outer vessel (11) with a peripheral wall (13) and two end walls (15, 16) in such a way that at least at one end a walkable cavity (29) is formed between one end wall (16) of the outer vessel (11) and the adjacent end wall (16) of the inner vessel (12), a closable manhole (33) being provided on the top of the outer vessel (11) and of several line connections (24) on the inner vessel (12), to which line feedthroughs (40) leading to the outside are assigned, characterized in that the line connections (24; 124) of the inner container (12; 112) are arranged in the upper apex zone of its peripheral wall (14; 114) and that in the peripheral wall (13: 113a) of the outer container (11; 111) at its cavity-side end part an upwardly projecting, externally closed dome (30; 130) is formed, which is provided with the manhole (33; 133) and equipped with the line feedthroughs (40; 140). 2. Pressure vessel according to claim 1, characterized in that the inner vessel (12; 112) extends with its one end axially into the area of the zone of the outer vessel (11; 111) occupied by the dome (30; 130) and that line connections are provided essentially in the peripheral wall (14; 114) of this end of the inner vessel (12; 112). a» ■«·· « ■ · ·■ I · 1 · f I · · I ItIiI · 1 t · · II · * » II · · I - 18 (24;124) are provided. 3. Pressure vessel according to claim 1 or 2,
characterized in that
the dome (30) is designed as a tower structure with side walls (32) and top wall (31) and is welded with its lower edge (32a) into an opening (36) of the outer container (11) and that the line ducts (40) are arranged in the side wall (32) and/or the top wall (31) of the dome (30). 4. Pressure vessel according to one of claims 1 to 3,
characterized in that
the manhole (33) is provided eccentrically in the upper wall (31) of the dome (30). 5. Pressure vessel according to one of claims 1 to 4,
characterized in that
the dome (30) is surrounded by an open shaft pipe (49) and that a walkable grating (46) is arranged in the space between the side wall (32) of the dome (30) and the shaft pipe (49). 6. Pressure vessel according to claim 1 or 2,
characterized in that
the dome (130) is designed as an elongated eccentric upper extension of the peripheral wall (113a) of the outer container (IiI), that the manhole (133) and the line duct (140) are provided next to each other in the apex zone of the extension in the direction of the longitudinal axis and that the line connections (124) and a manhole (120) are arranged in the apex zone of the inner container (112) in the area of the extension. 7. Pressure vessel according to claim 6, characterized in that
the cable bushings (140) and the cable connections (124) are located vertically one above the other and are arranged in several parallel rows. 8. Pressure vessel according to claim 6 or 7,
characterized in that &iacgr;&idiagr;&iacgr;&ogr; FruoUonmn rioc All ßenhohü 1 t" P r K (111) is formed from a ring section of larger diameter which is connected via an inclined wall (146) to the peripheral wall (113) of smaller diameter. 9. Pressure vessel according to one of claims 1 to 8,
characterized in that the outer container (111) and the inner container (112) each have a manhole (153,133;119,120) at the end facing away from the dome (130) in the apex zone.