US3583479A - Pressure relief devices - Google Patents
Pressure relief devices Download PDFInfo
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- US3583479A US3583479A US840764A US3583479DA US3583479A US 3583479 A US3583479 A US 3583479A US 840764 A US840764 A US 840764A US 3583479D A US3583479D A US 3583479DA US 3583479 A US3583479 A US 3583479A
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- duct
- liquid metal
- membrane
- shell
- closure membrane
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C9/00—Emergency protection arrangements structurally associated with the reactor, e.g. safety valves provided with pressure equalisation devices
- G21C9/002—Emergency protection arrangements structurally associated with the reactor, e.g. safety valves provided with pressure equalisation devices against Na- or Ka- reactions
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K17/00—Safety valves; Equalising valves, e.g. pressure relief valves
- F16K17/02—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side
- F16K17/14—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side with fracturing member
- F16K17/16—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side with fracturing member with fracturing diaphragm ; Rupture discs
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B1/00—Methods of steam generation characterised by form of heating method
- F22B1/02—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers
- F22B1/06—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers the heat carrier being molten; Use of molten metal, e.g. zinc, as heat transfer medium
- F22B1/063—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers the heat carrier being molten; Use of molten metal, e.g. zinc, as heat transfer medium for metal cooled nuclear reactors
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T137/00—Fluid handling
- Y10T137/1624—Destructible or deformable element controlled
- Y10T137/1632—Destructible element
- Y10T137/1669—Tensile or sheer pin or bolt
- Y10T137/1677—Pressure causes pin or bolt to destruct
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T137/00—Fluid handling
- Y10T137/1624—Destructible or deformable element controlled
- Y10T137/1632—Destructible element
- Y10T137/1692—Rupture disc
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T137/00—Fluid handling
- Y10T137/1624—Destructible or deformable element controlled
- Y10T137/1632—Destructible element
- Y10T137/1774—With counterbalancing element
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T137/00—Fluid handling
- Y10T137/1624—Destructible or deformable element controlled
- Y10T137/1632—Destructible element
- Y10T137/1789—Having pressure responsive valve
Definitions
- a safety expedient In combination with a heat exchanger of the tube-in-shell type in which water/steam flows in the tubes and a liquid metal such as sodium flows in the closed shell and over the tubes, a safety expedient comprises a duct communicating with the lower region of the shell well below the operating level of liquid metal therein, a storage vessel to which said duct leads and which is disposed at a lower level than that of said shell, and a pressure relief device disposed in said duct and normally closing it but capable of opening said duct on the occurrence of an overpressure in said shell such as will be caused by evolution of hydrogen from reaction between the liquid metal and water/steam on failure of a heat exchange tube.
- This invention relates to a safety expedient applicable where two reacting substances, one a liquid metal (such as sodium) and the other water/steam, flow in heat exchange relationship with the interposition between the substances of a barrier material, such as the walls of a nest of tubes extending into and out of a closed vessel, the water/steam flowing through the tubes and the liquid metal flowing over the tubes.
- a barrier material such as the walls of a nest of tubes extending into and out of a closed vessel, the water/steam flowing through the tubes and the liquid metal flowing over the tubes.
- Local failure of the barrier material will permit contact between the liquid metal and water/steam, the resulting violent reaction producing hydrogen and causing a pressure rise in the closed vessel.
- the pressure rise if not relieved, can cause further failures of the barrier material, which leads to further reaction and further pressure rise, and an explosion ultimately may occur.
- the present invention deals with the sodium/water reaction problem by employing a new concept, namely that the pressure rise following from such reaction is employed, together with gravity, to remove sodium from the reaction zone, thus avoiding the explosive hazard which could arise from following the expedient hitherto provided in the situation where the arrangement for removing steam/water from the tubes failed to operate, or operation was not effected in time.
- a safety expedient in combination with a liquid metal/water or steam heat exchanger of the tube-inshell type intended to operate so that water/steam flows in the tubes and liquid metal flows in the closed shell and over the tubes, a safety expedient is characterized by a duct communicating with the lower region of the shell well below the operating level of liquid metal therein, said duc't leading to a storage vessel disposed at a lower level than that of said shell, and a pressure relief device disposed in said duct and normally closing it, whereby, on failure of a tube such that reaction between liquid metal and water/steam takes place and hydrogen is evolved, the resulting pressure rise in the shell operates the pressure relief device to open the duct and also, together with the effect of gravity, forces liquid metal out of the shell and into the storage vessel.
- the pressure relief device preferably comprises a membrane normally preventing flow of liquid metal in said duct and of a material inert to liquid metal, and, on the downstream side of said membrane, a rigid backing supporting said membrane, said backing being pivotable from a position in which said membrane closes said duct into a position opening said duct, said backing being held in the duct-closing position by a shear pin designed to fail, together with said membrane, at a predetermined pressure of liquid metal whereupon 'the pressure of liquid metal opens the duct so that the liquid metal can flow therealong.
- a second membrane unsupported, downstream of said membrane and backing, to provide a holdup for said metal on premature opening or malfunctioning of the pressure relief device constituted by said membrane and backing, and also providing an interspace for the detection of any leakage from said pressure relief device.
- the said membrane or both of them are preferably of nickel sheet material.
- shear pin locations accessible from outside said duct, although one shear pin only is employed in operation, allowing a shear pin to-be removed and replaced on routine inspection'by employing a temporary shear pin in the alternative location.
- FIG. I is a diagrammatic flow diagram
- FIG. 2 is a fragmentary side view in medial section
- FIG. 3 is an end view in section on line III-III of FIG. -2.
- FIGS. 2 and 3 illustrate the provis'ion of a pressure relief device 1 in a duct 2 for liquid metal, such as sodium, at an elevated temperature ('e.g. 350 C.), the device 1 forming part of a safety expedient, illustrated in FIG. 1, for a liquid metal heated steam generator, reheater or superheater, such for example as is required for a power-producing, liquid metal cooled, fast breeder nuclear reactor such as the Prototype Fast Reactor (P.F.R.), now being constructed at Doun'rea'y, Scotland.
- a typical sodium heated steam generator or superheater, which is of the tube-in-shell type, is shown diagrammatically in FIG.
- a pressure vessel 4 containing heat exchange tubes, indicated diagrammatically by dot-and-dash lines 5, of U-configuration and terminating at their ends in water or steam headers 6, 7 respectively.
- the tube/tube plate welds are isolated from liquid metal by inert gas (e.g. argon) spaces 8, 9 above the liquid metal levels I0, 11 and a partition 12 isolates the gas spaces 8, 9 from one another.
- An inlet 13 to the pressure vessel is provided for sodium in a secondary circuit, which sodium flows downwardly then upwardly over the U-tubes'S, leaving the pressure vessel 4 at outlet 14.
- Each secondary circuit includes one side of heat exchangers in the primary sodium circuit of the reactor, a circulating pump, and a steam generator, superheater and reheater.
- a further outlet 15 is provided at the lower end region of the'pressure vessel 4 with which the duct 2 communicates, the latter being normally closed by the pressure relief device 1.
- the outlet 1 5 for the duct 2 can with advantage be at the lowest point of the vessel 4 assuming that sufficient room exists for the subsequently-described storage vessel at a lower level.
- the device is intended to operate should a heat exchange tube 5 fail during operation, therebyallowing water or steam to come into contact with the flowing sodium.
- the pressure relief device 1 in the duct 2 comprises a sheet nickel disc membrane 17 whose peripheral edge is sealingly held between a pair of annular joint rings 18 also of nickel, the joint rings 18 being themselves sealingly held between flanges 19, 20 of two portions 21, 22 respectively of tubes constituting the duct 2.
- the flanges 19, 20 are held in sealing engagement against the rings 18 by rings 23, 24 which engage nonsealing faces of the flanges 19, 20, and by a plurality of bolts 25 extending between the rings 23, 24-.
- annular soft metal backing ring 26 in engagement with the outer circumferential surfaces of the flanges 23, 24.
- the flange 20 of the duct portion 22 has an inwardly projecting lug 27 which is apertured at 28 to form a pivot for a backing plate 29 for the membrane 17.
- the pivot is formed by two spaced diametrical members 30 welded to the plate 29 and pivotally mounted at one of their ends on a pivot pin 3! accommodated in the aperture 28 of the lug 27.
- the members 30 are welded at their other ends to a shear pin block 32 having two radially extending blind holes 33, 34.
- the flange 20 of the duct portion 22 has an inwardly extending block 35 welded to it at a position diametrically opposed to that of the lug 27, the inner surface of the block 35 registering with and just clearing the outer surface of the block 32.
- the block 35 and the flange 20 have registering apertures 36, 37 which also register with the blind holes 33, 34 respectively,
- the apertures in the flange 20 each have an upper portion of increased diameter and screw threaded for a cap bolt 38; a shear pin 39 with a head 40 for engaging the increased diameter portion is employed in one of the pairs of registering apertures and blind holes 36, 33 or 37, 34, the other being left for changeover pur poses. It is advantageous that the shear pin locations are accessible from outside the duct, enabling routine inspection to be performed without dismantling any pipework.
- a backup dished-disc membrane 41 whose peripheral edge is trapped in sealing manner between a flange 42 welded to the interior of the duct portion 22 and a ring 43 fastened to the flange 42 by bolted studs 44.
- O-ring seals 45 are provided on the opposed faces of the flange 42 and ring 43 to seal against the membrane 41.
- a bellows joint 46 is interposed in the duct 2 downstream of the pressure relief device 1, and in a modification, the backup membrane 41 can be incorporated between flanges which form part of the bellows construction (not shown but of conventional type).
- the characteristics of the pin 39 in shear are chosen so that the pin will fail at a desired overpressure in the pressure vessel.
- the pressure causes the membrane 17 to fail also, and the plate 29 is forced to pivot and assume an open position, thereby allowing sodium to flow along duct 2 into the storage vessel 16.
- the membrane 17 can be designed to fail at any desired pressure within a small percentage error, it will be appreciated that particularly at high temperatures when the nonnal working pressure is close to the failure pressure, the working life of the membrane 17 would be severely reduced if provided unsupported. However, when supported as described, the stresses in the membrane 17 are reduced and its life prolonged.
- the membrane 17 (which will fail with the shear pin 39) still serves a useful purpose in that it seals the duct 2 during normal operation (it would be extremely difficult to seal against hot sodium around the periphery of the backing plate if this had to function as a flap valve) and also, because it forms the barrier for the hot sodium, it enables the material of the backing plate 29, members 30 and blocks 32, 35 to be of conventional (and hence cheaper) materials compared with the special materials which would be necessary if these parts had to have good and long term corrosion resistance in hot sodium.
- the backup membrane 41 is provided to delay the discharge of the whole sodium content of the heat exchange circuit involved where, due to some maloperation or unintended failure, the barrier provided by the membrane 17 and backing plate 29 becomes removed prematurely and without being caused by a tube failure in the heat exchanger.
- the back up membrane 41 is designed to fail subsequently to failure of the membrane 17 consequent on a pressure rise in the vessel 4 due to the occurrence of a sodium, steam/water reaction arising from failure of one of the heat exchanger tubes 5.
- the membrane 41 can also serve to provide an interspace 47 so that, should there by unintentional leakage of sodium past the initial barrier, it can be detected within the interspace 47 by conventional means (not shown) and remedial measures to prevent the leakage can be taken, without losing sodium to the storage vessel 16.
- the storage vessel 16 is preferably provided (not shown) with a normally closed, high, vent line so that hydrogen which becomes entrained in the sodium or reaches the tank 16 after the sodium has reached it, can be vented to atmosphere.
- the vent line top has a simple pressure-frangible diaphragm to allow the venting, and conventional means are provided for removing any entrained sodium from the gas to be vented.
- a safety expedient comprising a duct communicating with the shell at the lower end thereof, a storage vessel to which said duct leads and which is disposed at a lower level than that of said shell and a pressure relief device disposed in said duct and normally closing it, said pressure relief device comprising a closure membrane, means supporting and sealing the closure membrane in the duct, said closure membrane normally preventing flow of liquid metal in said duct and being of a material inert to liquid metal, and, on the downstream side of said closure membrane, a rigid backing member bearing against and supporting said closure membrane, said rigid backing member being pivotable from the position supporting said closure membrane to a position leaving the duct open on failure of the closure membrane, said rigid backing member being held in the position supporting the closure membrane by a shear pin designed to fail, together with said closure membrane, on a pressure rise in the heat exchanger shell such as would be caused
- a safety expedient according to claim 1 whereby a second membrane is provided without a rigid backing member downstream of said closure membrane and backing member, means being provided supporting and sealing said second membrane in the duct, said second membrane being provided to act as a holdup for liquid metal on premature opening or malfunctioning of the pressure relief device constituted by said closure membrane and the rigid backing member, said second membrane being designed to fail and allow the flow of liquid metal along the duct subsequent to failure of said closure membrane and release of the backing member by failure of the shear pin holding the backing member in the position supporting the closure membrane consequent on a pressure rise in the shell due to the occurrence of a liquid metal steam/water reaction on failure of a heat exchanger tube, said second membrane also providing an interspace for the detection of any leakage from said pressure relief device.
Abstract
In combination with a heat exchanger of the tube-in-shell type in which water/steam flows in the tubes and a liquid metal such as sodium flows in the closed shell and over the tubes, a safety expedient comprises a duct communicating with the lower region of the shell well below the operating level of liquid metal therein, a storage vessel to which said duct leads and which is disposed at a lower level than that of said shell, and a pressure relief device disposed in said duct and normally closing it but capable of opening said duct on the occurrence of an overpressure in said shell such as will be caused by evolution of hydrogen from reaction between the liquid metal and water/steam on failure of a heat exchange tube. Thus the overpressure aided by the force of gravity will force the liquid metal out of the shell and into the storage vessel. A particularly suitable form of pressure relief device is described. Isolation of the heat exchanger from liquid metal, and additionally from water/steam if desired, can be initiated by evolution of hydrogen in said shell.
Description
United States Patent [721 Inventors Derek Taylor Knutsford; Michael John Watts, Culcheth, Warrington, both of, England 1211 Appl. No. 840,764 1221 Filed July 10, 1969 [45] Patented June 8, 1971 I731 Assignee United Kingdom Atomic Energy Authority London, England [32] Priority July 18, 1968 1331 Great Britain [31] 34421/68 [54] PRESSURE RELIEF DEVICES 4 Claims, 3 Drawing Figs.
[52] U.S.Cl 165/134, 122/32, 165/158, 137/68,137/69,l37/71, 176/37, 220/89A [51] Int. Cl F281 9/00 [501 Field of Search 165/134, 158; 122/32; 137/68,69, 71;220/89 A; 176/37 [56] References Cited UNITED STATES PATENTS 2,079,164 5/1937 Glab 137/69X I I I I 8? 9 l 1... T 5/ I I l 2,128,039 8/1938 Cibulka 137/69 2,895,492 7/1959 Bell 137/68 3,398,789 8/1968 Wolowodiuk et al 165/134 3,438,431 4/1969 Dreyer et al. 165/134 Primary Examiner-Albert W. Davis, Jr. Anorney-Larson, Taylor and Hinds ABSTRACT: In combination with a heat exchanger of the tube-in-shell type in which water/steam flows in the tubes and a liquid metal such as sodium flows in the closed shell and over the tubes, a safety expedient comprises a duct communicating with the lower region of the shell well below the operating level of liquid metal therein, a storage vessel to which said duct leads and which is disposed at a lower level than that of said shell, and a pressure relief device disposed in said duct and normally closing it but capable of opening said duct on the occurrence of an overpressure in said shell such as will be caused by evolution of hydrogen from reaction between the liquid metal and water/steam on failure of a heat exchange tube. Thus the overpressure aided by the force of gravity will force the liquid metal out of the shell and into the storage vessel. A particularly suitable form of pressure relief device is described. Isolation of the heat exchanger from liquid metal, and additionally from water/steam if desired, can be initiated by evolution of hydrogen in said shell.
Hitherto, in a sodium/water heat exchange system of the tube-in-shell type employing U-shaped tubes and in which, to avoid having the tube plates and tube/tube plate welds in a sodium environment, an inert gas space is provided above the sodium at each end of the tubes, pressure relief means of the bursting disc-type has been provided to relieve high pressure in such gas spaces when caused by the hydrogen evolved in the sodium/water reaction on failure of one or more tubes. Such pressure relief has been augmented by a separately controlled arrangement whereby the steam/water can be removed from the tubes by allowing the steam to flash off, and the water feed to the tubes can be interrupted.
SUMMARY OF THE INVENTION The present invention deals with the sodium/water reaction problem by employing a new concept, namely that the pressure rise following from such reaction is employed, together with gravity, to remove sodium from the reaction zone, thus avoiding the explosive hazard which could arise from following the expedient hitherto provided in the situation where the arrangement for removing steam/water from the tubes failed to operate, or operation was not effected in time.
Hence, according to the invention, in combination with a liquid metal/water or steam heat exchanger of the tube-inshell type intended to operate so that water/steam flows in the tubes and liquid metal flows in the closed shell and over the tubes, a safety expedient is characterized by a duct communicating with the lower region of the shell well below the operating level of liquid metal therein, said duc't leading to a storage vessel disposed at a lower level than that of said shell, and a pressure relief device disposed in said duct and normally closing it, whereby, on failure of a tube such that reaction between liquid metal and water/steam takes place and hydrogen is evolved, the resulting pressure rise in the shell operates the pressure relief device to open the duct and also, together with the effect of gravity, forces liquid metal out of the shell and into the storage vessel.
The pressure relief device preferably comprises a membrane normally preventing flow of liquid metal in said duct and of a material inert to liquid metal, and, on the downstream side of said membrane, a rigid backing supporting said membrane, said backing being pivotable from a position in which said membrane closes said duct into a position opening said duct, said backing being held in the duct-closing position by a shear pin designed to fail, together with said membrane, at a predetermined pressure of liquid metal whereupon 'the pressure of liquid metal opens the duct so that the liquid metal can flow therealong.
There is preferably provided a second membrane, unsupported, downstream of said membrane and backing, to provide a holdup for said metal on premature opening or malfunctioning of the pressure relief device constituted by said membrane and backing, and also providing an interspace for the detection of any leakage from said pressure relief device.
The said membrane or both of them are preferably of nickel sheet material.
There are preferably two shear pin locations, accessible from outside said duct, although one shear pin only is employed in operation, allowing a shear pin to-be removed and replaced on routine inspection'by employing a temporary shear pin in the alternative location.
DESCRIPTION OF THE DRAWINGS A constructional example embodying the invention will now be described with reference to the accompanying drawings, wherein FIG. I is a diagrammatic flow diagram,
FIG. 2 is a fragmentary side view in medial section, and
FIG. 3 is an end view in section on line III-III of FIG. -2.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, FIGS. 2 and 3 illustrate the provis'ion of a pressure relief device 1 in a duct 2 for liquid metal, such as sodium, at an elevated temperature ('e.g. 350 C.), the device 1 forming part of a safety expedient, illustrated in FIG. 1, for a liquid metal heated steam generator, reheater or superheater, such for example as is required for a power-producing, liquid metal cooled, fast breeder nuclear reactor such as the Prototype Fast Reactor (P.F.R.), now being constructed at Doun'rea'y, Scotland. A typical sodium heated steam generator or superheater, which is of the tube-in-shell type, is shown diagrammatically in FIG. 1 and designated generally by the reference numeral 3, and consists of a shell embodied by a pressure vessel 4 containing heat exchange tubes, indicated diagrammatically by dot-and-dash lines 5, of U-configuration and terminating at their ends in water or steam headers 6, 7 respectively. The tube/tube plate welds are isolated from liquid metal by inert gas (e.g. argon) spaces 8, 9 above the liquid metal levels I0, 11 and a partition 12 isolates the gas spaces 8, 9 from one another. An inlet 13 to the pressure vessel is provided for sodium in a secondary circuit, which sodium flows downwardly then upwardly over the U-tubes'S, leaving the pressure vessel 4 at outlet 14. Each secondary circuit includes one side of heat exchangers in the primary sodium circuit of the reactor, a circulating pump, and a steam generator, superheater and reheater.
A further outlet 15 is provided at the lower end region of the'pressure vessel 4 with which the duct 2 communicates, the latter being normally closed by the pressure relief device 1. Although shown in FIG. 1 in'the lower end region of the vessel 4, the outlet 1 5 for the duct 2 can with advantage be at the lowest point of the vessel 4 assuming that sufficient room exists for the subsequently-described storage vessel at a lower level. The device is intended to operate should a heat exchange tube 5 fail during operation, therebyallowing water or steam to come into contact with the flowing sodium. In this event, a rapid reaction will ensue and hydrogen will be generated which will rapidly raise the pressure within the pressure vessel and,added to the load on the pressure relief device which is manifest by the pressure drop in the sodium and the sodium head itself, will operate the pressure relief device 1, open the outlet 15 and force the sodium, aided by gravity, from the pressure vessel 4 into the duct 2 to flow along duct 2 to -a storage vessel 16 designed to accept more than the full quantity of sodium in the particular heat exchanger concerned. The storage vessel 16 and that part of the duct -2 downstream of the pressure relief device 1 is normally at atmospheric pressure. It is arranged by conventional fault circuitr-y that when the pressure relief device 1 operates, or when evolution of hydrogen in the vessel 4 is detected by suitable monitoring equipment, the nuclear reactor is shut down and the affected heat exchanger is isolated from sodium. It can be additionally arranged that the steam is flashed off from the steam circuit of the affected heat exchanger and where the heat exchanger is a steam generator, the generator is isolated from water. Such additional measures provide a safeguard which augments the'main safeguard provided by removing the sodium from the vessel 4 and preventing the entry of further sodium to the vessel 4 from the said secondary of circuit by the said isolation.
Referring again to FIGS. 2 and 3, the pressure relief device 1 in the duct 2 comprises a sheet nickel disc membrane 17 whose peripheral edge is sealingly held between a pair of annular joint rings 18 also of nickel, the joint rings 18 being themselves sealingly held between flanges 19, 20 of two portions 21, 22 respectively of tubes constituting the duct 2. The flanges 19, 20 are held in sealing engagement against the rings 18 by rings 23, 24 which engage nonsealing faces of the flanges 19, 20, and by a plurality of bolts 25 extending between the rings 23, 24-. Additionally there is an annular soft metal backing ring 26 in engagement with the outer circumferential surfaces of the flanges 23, 24.
The flange 20 of the duct portion 22 has an inwardly projecting lug 27 which is apertured at 28 to form a pivot for a backing plate 29 for the membrane 17. The pivot is formed by two spaced diametrical members 30 welded to the plate 29 and pivotally mounted at one of their ends on a pivot pin 3! accommodated in the aperture 28 of the lug 27. The members 30 are welded at their other ends to a shear pin block 32 having two radially extending blind holes 33, 34. The flange 20 of the duct portion 22 has an inwardly extending block 35 welded to it at a position diametrically opposed to that of the lug 27, the inner surface of the block 35 registering with and just clearing the outer surface of the block 32. The block 35 and the flange 20 have registering apertures 36, 37 which also register with the blind holes 33, 34 respectively, The apertures in the flange 20 each have an upper portion of increased diameter and screw threaded for a cap bolt 38; a shear pin 39 with a head 40 for engaging the increased diameter portion is employed in one of the pairs of registering apertures and blind holes 36, 33 or 37, 34, the other being left for changeover pur poses. It is advantageous that the shear pin locations are accessible from outside the duct, enabling routine inspection to be performed without dismantling any pipework. At an axial position in the duct 2 which is clear of the pivotal arc of the backing plate 29 and block 32 there is provided a backup dished-disc membrane 41 whose peripheral edge is trapped in sealing manner between a flange 42 welded to the interior of the duct portion 22 and a ring 43 fastened to the flange 42 by bolted studs 44. O-ring seals 45 are provided on the opposed faces of the flange 42 and ring 43 to seal against the membrane 41. A bellows joint 46 is interposed in the duct 2 downstream of the pressure relief device 1, and in a modification, the backup membrane 41 can be incorporated between flanges which form part of the bellows construction (not shown but of conventional type).
The characteristics of the pin 39 in shear are chosen so that the pin will fail at a desired overpressure in the pressure vessel. When the pin 39 fails, the pressure causes the membrane 17 to fail also, and the plate 29 is forced to pivot and assume an open position, thereby allowing sodium to flow along duct 2 into the storage vessel 16. Although the membrane 17 can be designed to fail at any desired pressure within a small percentage error, it will be appreciated that particularly at high temperatures when the nonnal working pressure is close to the failure pressure, the working life of the membrane 17 would be severely reduced if provided unsupported. However, when supported as described, the stresses in the membrane 17 are reduced and its life prolonged. By employing the backing plate 29 to give rigidity to the membrane 17 and the shear pin 39 to fail at a desired overpressure, the membrane 17 (which will fail with the shear pin 39) still serves a useful purpose in that it seals the duct 2 during normal operation (it would be extremely difficult to seal against hot sodium around the periphery of the backing plate if this had to function as a flap valve) and also, because it forms the barrier for the hot sodium, it enables the material of the backing plate 29, members 30 and blocks 32, 35 to be of conventional (and hence cheaper) materials compared with the special materials which would be necessary if these parts had to have good and long term corrosion resistance in hot sodium.
The backup membrane 41 is provided to delay the discharge of the whole sodium content of the heat exchange circuit involved where, due to some maloperation or unintended failure, the barrier provided by the membrane 17 and backing plate 29 becomes removed prematurely and without being caused by a tube failure in the heat exchanger. The back up membrane 41 is designed to fail subsequently to failure of the membrane 17 consequent on a pressure rise in the vessel 4 due to the occurrence of a sodium, steam/water reaction arising from failure of one of the heat exchanger tubes 5. The membrane 41 can also serve to provide an interspace 47 so that, should there by unintentional leakage of sodium past the initial barrier, it can be detected within the interspace 47 by conventional means (not shown) and remedial measures to prevent the leakage can be taken, without losing sodium to the storage vessel 16.
The storage vessel 16 is preferably provided (not shown) with a normally closed, high, vent line so that hydrogen which becomes entrained in the sodium or reaches the tank 16 after the sodium has reached it, can be vented to atmosphere. The vent line top has a simple pressure-frangible diaphragm to allow the venting, and conventional means are provided for removing any entrained sodium from the gas to be vented.
We claim:
- 1. In combination with a heat exchanger of the tube-in-shell type for operating so that water/steam flows in the tubes and liquid metal flow in the closed shell and over the tubes a safety expedient comprising a duct communicating with the shell at the lower end thereof, a storage vessel to which said duct leads and which is disposed at a lower level than that of said shell and a pressure relief device disposed in said duct and normally closing it, said pressure relief device comprising a closure membrane, means supporting and sealing the closure membrane in the duct, said closure membrane normally preventing flow of liquid metal in said duct and being of a material inert to liquid metal, and, on the downstream side of said closure membrane, a rigid backing member bearing against and supporting said closure membrane, said rigid backing member being pivotable from the position supporting said closure membrane to a position leaving the duct open on failure of the closure membrane, said rigid backing member being held in the position supporting the closure membrane by a shear pin designed to fail, together with said closure membrane, on a pressure rise in the heat exchanger shell such as would be caused by evolution of hydrogen from reaction between the liquid metal and water/steam on failure of a heat exchanger tube, thereby opening the duct on failure of the closure membrane and pivoting of the rigid backing member to allow flow ofliquid metal from the heat exchanger shell through the duct into the storage vessel.
2. A safety expedient according to claim 1 whereby a second membrane is provided without a rigid backing member downstream of said closure membrane and backing member, means being provided supporting and sealing said second membrane in the duct, said second membrane being provided to act as a holdup for liquid metal on premature opening or malfunctioning of the pressure relief device constituted by said closure membrane and the rigid backing member, said second membrane being designed to fail and allow the flow of liquid metal along the duct subsequent to failure of said closure membrane and release of the backing member by failure of the shear pin holding the backing member in the position supporting the closure membrane consequent on a pressure rise in the shell due to the occurrence of a liquid metal steam/water reaction on failure of a heat exchanger tube, said second membrane also providing an interspace for the detection of any leakage from said pressure relief device.
3. A safety expedient according to claim 2, wherein the liquid metal is sodium and said closure membrane is of nickel.
4. A safety expedient according to claim 1, wherein there are two shear pin locations, accessible from outside said duct, although one shear pin only is employed in operation, allowing a shear pin to be removed and replaced on routine inspection by employing a temporary shear pin in the alternative iocation.
Claims (4)
1. In combination with a heat exchanger of the tube-in-shell type for operating so that water/steam flows in the tubes and liquid metal flow in the closed shell and over the tubes a safety expedient comprising a duct communicating with the shell at the lower end thereof, a storage vessel to which said duct leads and which is disposed at a lOwer level than that of said shell and a pressure relief device disposed in said duct and normally closing it, said pressure relief device comprising a closure membrane, means supporting and sealing the closure membrane in the duct, said closure membrane normally preventing flow of liquid metal in said duct and being of a material inert to liquid metal, and, on the downstream side of said closure membrane, a rigid backing member bearing against and supporting said closure membrane, said rigid backing member being pivotable from the position supporting said closure membrane to a position leaving the duct open on failure of the closure membrane, said rigid backing member being held in the position supporting the closure membrane by a shear pin designed to fail, together with said closure membrane, on a pressure rise in the heat exchanger shell such as would be caused by evolution of hydrogen from reaction between the liquid metal and water/steam on failure of a heat exchanger tube, thereby opening the duct on failure of the closure membrane and pivoting of the rigid backing member to allow flow of liquid metal from the heat exchanger shell through the duct into the storage vessel.
2. A safety expedient according to claim 1 whereby a second membrane is provided without a rigid backing member downstream of said closure membrane and backing member, means being provided supporting and sealing said second membrane in the duct, said second membrane being provided to act as a holdup for liquid metal on premature opening or malfunctioning of the pressure relief device constituted by said closure membrane and the rigid backing member, said second membrane being designed to fail and allow the flow of liquid metal along the duct subsequent to failure of said closure membrane and release of the backing member by failure of the shear pin holding the backing member in the position supporting the closure membrane consequent on a pressure rise in the shell due to the occurrence of a liquid metal steam/water reaction on failure of a heat exchanger tube, said second membrane also providing an interspace for the detection of any leakage from said pressure relief device.
3. A safety expedient according to claim 2, wherein the liquid metal is sodium and said closure membrane is of nickel.
4. A safety expedient according to claim 1, wherein there are two shear pin locations, accessible from outside said duct, although one shear pin only is employed in operation, allowing a shear pin to be removed and replaced on routine inspection by employing a temporary shear pin in the alternative location.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB34421/68A GB1276838A (en) | 1968-07-18 | 1968-07-18 | Improvements in or relating to pressure relief devices |
Publications (1)
Publication Number | Publication Date |
---|---|
US3583479A true US3583479A (en) | 1971-06-08 |
Family
ID=10365436
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US840764A Expired - Lifetime US3583479A (en) | 1968-07-18 | 1969-07-10 | Pressure relief devices |
Country Status (6)
Country | Link |
---|---|
US (1) | US3583479A (en) |
JP (1) | JPS4840503B1 (en) |
DE (1) | DE1936409C3 (en) |
ES (1) | ES369625A1 (en) |
FR (1) | FR2013194B1 (en) |
GB (1) | GB1276838A (en) |
Cited By (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3854522A (en) * | 1971-04-14 | 1974-12-17 | United States Steel Corp | High service temperature pressure sensitive device |
US3924675A (en) * | 1973-05-03 | 1975-12-09 | Us Energy | Energy absorber for sodium-heated heat exchanger |
US4064003A (en) * | 1976-03-29 | 1977-12-20 | The United States Of America As Represented By The United States Energy Research And Development Administration | Rupture disc |
US4072183A (en) * | 1976-11-29 | 1978-02-07 | The United States Of America As Represented By The United States Department Of Energy | Heat exchanger with intermediate evaporating and condensing fluid |
US4157939A (en) * | 1974-04-16 | 1979-06-12 | Kraftwerk Union Aktiengesellschaft | Pressurized-water reactor emergency core shutdown |
US4469051A (en) * | 1982-03-31 | 1984-09-04 | Novatome | Emergency shut-off device, in case of leakage of a steam generator tube |
US4589478A (en) * | 1985-08-19 | 1986-05-20 | United Aircraft Products, Inc. | Pressure protected tubular heat exchanger |
US4589375A (en) * | 1983-04-07 | 1986-05-20 | Commissariat A L'energie Atomique | Steam generator for a liquid metal-cooled reactor |
US4743424A (en) * | 1983-12-09 | 1988-05-10 | Hochtemperatur-Reaktorbau Gmbh | Nuclear reactor installation |
US4889151A (en) * | 1988-11-03 | 1989-12-26 | Oten Peter D | Snap action pressure relief valve with over pressure indicator |
US4927596A (en) * | 1988-08-12 | 1990-05-22 | Electric Power Research Institute, Inc. | Self-actuating pressure relief device and method for nuclear containment |
US5761261A (en) * | 1997-05-12 | 1998-06-02 | Florida Power Corporation | Ruptured disc accumulator |
US5984269A (en) * | 1995-08-25 | 1999-11-16 | Bs&B Safety Systems, Inc. | Rotatable valve assembly |
US10228069B2 (en) | 2015-11-06 | 2019-03-12 | Oklahoma Safety Equipment Company, Inc. | Rupture disc device and method of assembly thereof |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
AU505797B3 (en) * | 1979-08-10 | 1979-11-29 | Alister Leslie Mcculloch | Valve for automatic fire extinguishers |
GB8600441D0 (en) * | 1986-01-09 | 1986-02-12 | Thermal Technology Ltd | Pressure relief systems |
JPH01188793A (en) * | 1988-01-19 | 1989-07-28 | Power Reactor & Nuclear Fuel Dev Corp | Device for protecting bellows type pipe joint |
GB2269871B (en) * | 1992-08-20 | 1995-11-08 | Godiva Group Ltd | Variable attachment means |
JP3843416B2 (en) * | 1996-09-13 | 2006-11-08 | 東洋電機株式会社 | Pressure relief device used for heating device with saturated steam of heating medium |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2079164A (en) * | 1935-12-06 | 1937-05-04 | Morrison Brothers Company | Relief valve |
US2128039A (en) * | 1936-08-22 | 1938-08-23 | Standard Oil Dev Co | Pressure relief valve |
US2895492A (en) * | 1955-12-19 | 1959-07-21 | Foster Wheeler Corp | Pressure safety device |
US3398789A (en) * | 1965-01-25 | 1968-08-27 | Foster Wheeler Corp | Heat exchangers for pressure reacting fluids |
US3438431A (en) * | 1967-08-25 | 1969-04-15 | Siegfried Dreyer | Heat exchanger system |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE568051C (en) * | 1932-01-20 | 1933-01-13 | Neumann Berthold | Arrangement for the quick removal of overprints |
NL276268A (en) * | 1961-03-27 | |||
FR1518393A (en) * | 1966-05-31 | 1968-03-22 | Interatom | Heat exchange installation for metal-liquid / water exchange fluids |
-
1968
- 1968-07-18 GB GB34421/68A patent/GB1276838A/en not_active Expired
-
1969
- 1969-07-10 US US840764A patent/US3583479A/en not_active Expired - Lifetime
- 1969-07-17 FR FR6924401A patent/FR2013194B1/fr not_active Expired
- 1969-07-17 DE DE1936409A patent/DE1936409C3/en not_active Expired
- 1969-07-17 ES ES369625A patent/ES369625A1/en not_active Expired
- 1969-07-18 JP JP44056981A patent/JPS4840503B1/ja active Pending
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2079164A (en) * | 1935-12-06 | 1937-05-04 | Morrison Brothers Company | Relief valve |
US2128039A (en) * | 1936-08-22 | 1938-08-23 | Standard Oil Dev Co | Pressure relief valve |
US2895492A (en) * | 1955-12-19 | 1959-07-21 | Foster Wheeler Corp | Pressure safety device |
US3398789A (en) * | 1965-01-25 | 1968-08-27 | Foster Wheeler Corp | Heat exchangers for pressure reacting fluids |
US3438431A (en) * | 1967-08-25 | 1969-04-15 | Siegfried Dreyer | Heat exchanger system |
Cited By (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3854522A (en) * | 1971-04-14 | 1974-12-17 | United States Steel Corp | High service temperature pressure sensitive device |
US3924675A (en) * | 1973-05-03 | 1975-12-09 | Us Energy | Energy absorber for sodium-heated heat exchanger |
US4157939A (en) * | 1974-04-16 | 1979-06-12 | Kraftwerk Union Aktiengesellschaft | Pressurized-water reactor emergency core shutdown |
US4064003A (en) * | 1976-03-29 | 1977-12-20 | The United States Of America As Represented By The United States Energy Research And Development Administration | Rupture disc |
US4072183A (en) * | 1976-11-29 | 1978-02-07 | The United States Of America As Represented By The United States Department Of Energy | Heat exchanger with intermediate evaporating and condensing fluid |
US4469051A (en) * | 1982-03-31 | 1984-09-04 | Novatome | Emergency shut-off device, in case of leakage of a steam generator tube |
US4589375A (en) * | 1983-04-07 | 1986-05-20 | Commissariat A L'energie Atomique | Steam generator for a liquid metal-cooled reactor |
US4743424A (en) * | 1983-12-09 | 1988-05-10 | Hochtemperatur-Reaktorbau Gmbh | Nuclear reactor installation |
US4589478A (en) * | 1985-08-19 | 1986-05-20 | United Aircraft Products, Inc. | Pressure protected tubular heat exchanger |
US4927596A (en) * | 1988-08-12 | 1990-05-22 | Electric Power Research Institute, Inc. | Self-actuating pressure relief device and method for nuclear containment |
US4889151A (en) * | 1988-11-03 | 1989-12-26 | Oten Peter D | Snap action pressure relief valve with over pressure indicator |
US5984269A (en) * | 1995-08-25 | 1999-11-16 | Bs&B Safety Systems, Inc. | Rotatable valve assembly |
US5761261A (en) * | 1997-05-12 | 1998-06-02 | Florida Power Corporation | Ruptured disc accumulator |
US10228069B2 (en) | 2015-11-06 | 2019-03-12 | Oklahoma Safety Equipment Company, Inc. | Rupture disc device and method of assembly thereof |
Also Published As
Publication number | Publication date |
---|---|
ES369625A1 (en) | 1971-07-16 |
GB1276838A (en) | 1972-06-07 |
JPS4840503B1 (en) | 1973-11-30 |
FR2013194A1 (en) | 1970-03-27 |
DE1936409C3 (en) | 1978-09-21 |
DE1936409A1 (en) | 1970-01-22 |
FR2013194B1 (en) | 1973-10-19 |
DE1936409B2 (en) | 1978-01-12 |
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