EP0005494B1 - Vertical separator of a mixture of steam or gas and liquid or solid particles - Google Patents

Description

The present invention relates to a vertical separator of a mixture of vapor or gas and liquid or solid particles, comprising inside an external shell an inlet enclosure of said mixture, a plurality of vertical tubes provided at their inlet stationary vanes imparting a helical movement to the mixture, and at their exit from a coaxial tube of smaller diameter allowing in its internal duct the evacuation of dry vapor or gas, and in the annular space that of '' a mixture richer in liquid or solid particles, said annular space opening into a free volume allowing the separation of said mixture richer in liquid or solid particles into a substantially dry vapor or a gas and a fluid sparingly charged with vapor or gas, and said internal conduits opening into a chamber for collecting dry steam or gas.

Separation dryers in tubes by centrifugation effect having the advantage of a small footprint in relation to or flow of steam to be treated, and can therefore be arranged directly at the outlet of devices generating humidity in the steam, such as expansion turbines, by eliminating or reducing the lengths of piping transporting wet steam, and consequently subject to the phenomenon of erosion-corrosion. They make it possible to obtain a dry vapor of low residual water content, of the order of 0.1%, and consequently to minimize the volumes of water retained in the vapor circuits, and liable to vaporize during vapor pressure drops. However, the separated water is still mixed with steam, and even if it opens into a chamber allowing a certain separation by gravity, it is imperfect. The flowing water still causes a certain amount of steam which is lost for the thermodynamic cycle, which reduces the efficiency of the downstream devices (expansion turbines, exchangers). The steam which rises in this chamber still causes water droplets, so that it is difficult to use without precaution, and in particular risks causing corrosion on its circuit or requiring the use of expensive stainless steel pipes. .

The object of the present invention is to remedy the above drawbacks, and to provide a vertical separator which makes it possible on the one hand to obtain dry vapor or a gas of low residual content of liquid or solid particles, and on the other hand an additional fraction of vapor or gas freed from most of the residual liquid or solid particles, and containing only a few percent of residual particles, usable in thermodynamic circuits without special precautions. It also aims, in the case of the separation of a mixture of vapor or gas and a liquid, to minimize the quantity of liquid vaporized during a pressure drop of the vapor or gas, and reduce the pressure drop on the dry steam or gas circuit and the overall size of the separator.

The separator according to the invention is characterized in that it comprises at the bottom of the free volume a convex bottom with convexity facing upwards, an annular ring for collecting the fluid little charged with vapor or gas, and passages regularly arranged between the vertical tubes and allowing substantially dry vapor or gas to escape upward between the vertical tubes.

• - la chambre de recueil de vapeur sèche ou de gaz est reliée par le bas à un conduit d'évacuation de la vapeur sèche ou du gaz s'écartant latéralement de l'axe du séparateur avec un grand rayon de courbure.
• - la couronne annulaire de recueil du fluide peu chargé en vapeur ou en gaz est de faible volume et reliée à un récipient de grand volume de recueil dudit fluide, extérieur au séparateur.
• - ladite couronne annulaire est reliée au récipient de recueil par au moins deux conduits régulièrement répartis sur son pourtour.
• - il comprend deux ou plusieurs tubulures latérales d'évacuation de la vapeur sensiblement sèche ou de gaz échappés vers le haut entre les tubes verticaux, régulièrement réparties sur son pourtour.
• - l'enserrible de l'enceinte d'admission du mélange, des tubes de séparation et du fond convexe repose par le bord inférieur dudit fond convexe sur une couronne soudée à l'enveloppe externe du séparateur.
• - l'ensemble de l'enceinte d'admission et du volume libre autour des tubes verticaux de séparation est entouré par une enveloppe interne en métal résistant à l'érosion-corrosion par la vapeur d'eau humide circulant à grande vitesse, solidaire du fond convexe, et l'enveloppe externe est en un métal non résistant à l'érosion-corrosion par la vapeur d'eau humide circulant à grande vitesse
• - il comporte une enveloppe unique entourant directement l'enceinte d'admission du mélange et le volume libre autour des tubes de séparation, et le fond plat séparant l'enceinte d'admission et le volume libre autour des tubes est muni d'un rebord relevé vers le haut soudé sur la virole interne sur au moins une partie de son pourtour.
• - ledit rebord relevé vers le haut est soudé sur la virole externe dans des secteur où les tubes verticaux sont relativement éloignés du bord dudit fond plat, et il reste libre dans des secteurs où les tubes verticaux sont relativement proches du bord dudit fond plat.
• - l'intervalle entre le rebord relevé du fond et la virole externe, au moins dans les secteurs où ils ne sont pas soudés l'un à l'autre, est recouvert par des bandes d'étanchéité élastiques fixées de place en place à ladite virole externe.
• - ledit fond plat est muni sur son pourtour d'orifices reliés à des tubes coudés d'évacuation à l'extérieur de la virole de l'eau susceptible de se déposer sur lui
• - lesdits tubes coudés sont munis dans une partie verticale au voisinage dudit fond plat de soufflets de dilatation.

It also preferably includes at least one of the following characteristics:

• - the dry steam or gas collection chamber is connected from below to a discharge pipe for dry steam or gas which laterally deviates from the axis of the separator with a large radius of curvature.
• - The annular ring for collecting the fluid little loaded with vapor or gas is of small volume and connected to a container of large volume for collecting said fluid, outside the separator.
• - Said annular ring is connected to the collection container by at least two conduits regularly distributed around its periphery.
• - It comprises two or more lateral pipes for evacuating substantially dry steam or gases escaping upwards between the vertical tubes, regularly distributed around its periphery.
• - the ensrible of the mixture admission enclosure, the separation tubes and the convex bottom rests by the lower edge of said convex bottom on a crown welded to the outer casing of the separator.
• - the entire intake enclosure and the free space around the vertical separation tubes is surrounded by an internal metal envelope resistant to erosion and corrosion by wet steam circulating at high speed, secured to the convex bottom, and the outer casing is made of a metal that is not resistant to erosion-corrosion by moist water vapor circulating at high speed
• - It has a single envelope directly surrounding the intake enclosure of the mixture and the free volume around the separation tubes, and the flat bottom separating the intake enclosure and the free volume around the tubes is provided with a rim upwardly welded to the inner shell over at least part of its periphery.
• - Said raised edge is welded to the outer shell in sectors where the vertical tubes are relatively far from the edge of said flat bottom, and it remains free in sectors where the vertical tubes are relatively close from the edge of said flat bottom.
• - the interval between the raised edge of the bottom and the outer shell, at least in the sectors where they are not welded to each other, is covered by elastic sealing strips fixed from place to place to said outer shell.
• - Said flat bottom is provided on its periphery with orifices connected to bent evacuation tubes outside the ferrule of water likely to be deposited on it
• - said bent tubes are provided in a vertical part in the vicinity of said flat bottom with expansion bellows.

• La figure 1 représente une première forme de réalisation en coupe axiale.
• La figure 2 représente une coupe diamètrale selon l'axe II-II de la figure 1.
• La figure 3 représente une autre forme de réalisation en coupe axiale selon l'axe III-III de la figure 4, avec rabattement d'une partie de la coupe.
• La figure 4 représente une coupe diamétrale selon l'axe IV-IV de la figure 3.
• La figure 5A représente le détail A de la figure 3.
• La figure 5B représente le détail B de la figure 3.

It is described below, by way of examples and with reference to the figures of the appended drawing, two embodiments of a steam separator charged with water from an expansion turbine of a nuclear power plant, according to 'invention.

• Figure 1 shows a first embodiment in axial section.
• FIG. 2 represents a diametrical section along the axis II-II of FIG. 1.
• FIG. 3 shows another embodiment in axial section along the axis III-III of FIG. 4, with a part of the section being folded down.
• FIG. 4 represents a diametral section along the axis IV-IV of FIG. 3.
• FIG. 5A represents the detail A of FIG. 3.
• FIG. 5B represents the detail B of FIG. 3.

^- The elements common to FIGS. 1 and 2 on the one hand, 3 to 5 on the other hand, are represented with marks comprising as a digit hundreds 1 for FIGS. 1 and 2, and 3 for FIGS. 3 to 5.

In FIG. 1, the outer casing of the carbon steel separator comprises an upper frustoconical part 101, followed by a cylindrical part 102. Inside the frustoconical part is welded an access sleeve 3 made of stainless steel , to which is fixed a plate 104 for spacing the vertical separation tubes, with the interposition of an expansion joint 5. The separation tubes 106 have flared access orifices 107, joined by their edges so as to form a hexagonal paving (see figure 2). The tubes 106 are provided in the vicinity of their inlet with members 107A imparting a swirling motion to the humid steam. They comprise at their lower end devices 108 for separating the centrifuged water and the dry steam, the latter engaging in an internal tube 109 of smaller diameter. The tubes 109, provided with the flow straightening members 109A, are welded to a convex bottom 110 and open on the other side of the latter by mouths 111 into a tranquilization chamber for dry steam 112. The latter is connected to a dry steam discharge duct 113 with a large radius of curvature, so as to minimize the pressure drop on the dry steam circuit.

The curved bottom 110 constitutes the upper end of a cylindrical shell 14, welded to a circular crown 123, itself welded inside the external shell 102.

To the bracing plate 104 is fixed an outer ferrule 15, also made of stainless steel, the lower part of which defines, with the inner ferrule 14, an annular ring for collecting separate water 116, of small volume. This crown is connected by conduits 117, 118, at 180 ° from each other, to an external receptacle for separate water collection, of significantly larger volume, not shown. In this way, in the event of a pressure drop appearing on the wet steam circuit, the quantity of water liable to re-vaporize is small.

Furthermore, a peripheral sheet 19 surrounds the devices 108 for separating the centrifuged water from the dry steam, so as to avoid rising mixed water vapor towards the pipes 120, 121 for evacuating the substantially dry rising steam. between the tubes 106 from the devices 108. The tubes 120, 121 are at 180 ° from one another. The homogenization of the substantially dry vapor flow rates is ensured using deflectors such as 22 in front of the outlet pipes.

• La vapeur chargée d'humidité arrive verticalement vers le bas dans la manchette 3. Elle se répartit également entre les différents tubes, grâce aux entrées hexagonales 107 des tubes 106. La vapeur humide descend dans les tubes 106, après s'être vue imprimer un mouvement tourbillonnaire par les organes 107A. Sous l'effet de la force centrifuge, les gouttelettes d'eau sont projetées contre la paroi interne des tubes, le long de laquelle elles ruissellent. A la hauteur des extrémités inférieures des tubes de séparation 6, la vapeur sèche qui reste dans la zone axiale des tubes s'engage à l'intérieur des tubes 109 de plus faible diamètre, dans lesquels son mouvement tourbillonnaire est redressé par les organes 109A, puis traverse le fond bombé 110 et se rassemble dans la chambre de tranquillisation 112, d'où elle est envoyée à l'utilisation par la tuyauterie 113, à grand rayon de courbure.

The operation of the separator is as follows:

• The moisture-laden steam arrives vertically downwards in the cuff 3. It is also distributed between the different tubes, by means of the hexagonal inlets 107 of the tubes 106. The wet vapor descends into the tubes 106, after having been printed a vortex movement by organs 107A. Under the effect of centrifugal force, the water droplets are projected against the internal wall of the tubes, along which they run. At the height of the lower ends of the separation tubes 6, the dry vapor which remains in the axial zone of the tubes engages inside the tubes 109 of smaller diameter, in which its vortex movement is rectified by the members 109A, then crosses the curved bottom 110 and collects in the stilling chamber 112, from where it is sent for use by the piping 113, with a large radius of curvature.

From the mixture of water and steam which flows between the tubes 106 and 109, and whose vortex movement is rectified by members not shown, the relatively low humidity vapor escapes and rises between the tubes 106, passing through slots of defined width formed between these tubes, not shown, then is sent for use by the tubes 120 and 121. The remaining water collects in jets which descend along the outer periphery of the tubes 109 towards the convex bottom 110. The water then flows over this convex bottom towards the periphery thereof, where it collects in the annular crown 116. It is evacuated from this annular crown by the lines 117 and 118 at 180 ° from one another to a container for water recipe, not shown. It will be observed that the water and the water vapor, once separated at the level of the separation devices 108, follow entirely different paths, one downwards, the other upwards, and that there there is therefore no risk of re-mixing between water and steam. Furthermore, all of the differential expansions of the device, placed on the lower ring 123, are absorbed by the expansion joint 5 of the cuff 3. If one wishes to carry out repairs on the inlet of the tubes 106, there are advantageously manholes 24, 25 on the conical part 1 of the envelope and on the cuff 3.

In FIG. 3, the separator shell, made of stainless steel, so as to resist the erosion-corrosion action of wet steam at high speed, has a frustoconical part 301 on the side of the wet steam inlet , a central cylindrical part 302, and a frustoconical part 313 on the side for the evacuation of dry steam. The bottom 304 for separating the separation tubes 306 has an upwardly raised flange 26, welded on part of its periphery inside the ferrule, and free on the other part of it, as will be described below in more detail.

The separation tubes 306, of circular cross section, terminate above the bottom 304 by flared access orifices 307, joined by their edges so as to form a hexagonal passage (see FIG. 4), as in the case according to Figures 1 and 2.

They are provided at their entry with sets of inclined vanes 307A fixed on axial mandrels 306A, and imparting a steam vortex to the helical movement. They comprise at their lower end devices for separating centrifuged water and dry steam 308, the latter engaging in an internal tube 309, initially of smaller diameter than the tube 306. The tubes 309, provided with 'straightening steam flow vanes 309A, and flaring in the form of a truncated cone, so as to slow it down, are welded to the convex bottom 310, and terminate in orifices d flared outlet 311, meeting in a hexagonal pavement similar to that of the access orifices 307, and opening into the dry steam collection chamber 312. This is joined to a dry steam outlet duct, not represented.

The domed bottom 310 is welded to a circular crown 323, itself welded to the outer shell, and which thus supports all of the separation tubes.

The outer shroud, like that of FIG. 1, is fitted with pipes 317 for discharging the separated water to a collecting flask (not shown), and pipes for discharging water-depleted vapor 320.

The structure of the flat bottom 304 is more visible with reference to FIGS. 4, 5A, 5B. This is welded to the outer shell 301 by means of gussets 27 engaging in notches in the rim 26A (see FIG. 5A), along two sectors 28, forming an angle of 50 °, in the areas where the tubes are relatively far from the bottom edge. Its rim 26B is however free on the rest of the periphery (FIG. 5B), in the zones 29 where the tubes are closer to the rim of the bottom. In order to avoid leakage of wet steam along the latter, the upper part of the rim is covered by a double sealing blade 30A, 30B, bolted from place to place and tightened by nuts 35 on tabs 36 welded to the ferrule (FIGS. 5A, 5B).

A little moisture separating already before the entry of the mixture of water and steam into the separation tubes 306, the flat bottom 304 is provided with orifices 31 for discharging the water which is deposited there. These orifices opening onto bent evacuation tubes 32 provided with an expansion bellows 33, and opening to the outside of the shell by a tube 34. These tubes are connected to the same collecting flask as the tubes 317, by l 'intermediate U-shaped tubes providing compensation for the pressure difference.

Although the separators which have just been described with reference to the figures appear to be preferable embodiments, it will be understood that various modifications can be made to them without departing from the scope of the invention, some of their members being able to be replaced by others. who would play a similar technical role. In particular, the members intended to impart a swirling movement to wet steam can have any suitable shape, as well as those intended to straighten the movement, on the one hand dry steam on the other hand water, at the bottom tubes. The convex bottom separating the liquid chamber and the vapor stilling chamber can be replaced by a conical bottom.

The invention applies more particularly to separators of wet water vapor into dry steam and residual water, in particular in power generation plants. However, it can also be applied to the separation of liquid or solid particles conveyed by a vapor or by a gas.

Claims (12)

1. A vertical separator for a mixture of vapour or gas and of liquid or solid particles, including, inside an outer casing (101, 102) a chamber (3) for admitting the mixture, a plurality of vertical tubes (106) whose entries (107) are provided with fixed blades (107A) which impart a helical movement to the mixture and whose outlets are provided each with a coaxial tube (109) whose diameter is smaller and which allows dry vapour or gas to be removed in an inner tube and a mixture containing a higher proportion of liquid or solid particles to be removed in the annular space which leads into a free volume where said mixture containing a higher proportion of liquid or solid particles is allowed to be separated into substantially dry vapour or gas and a fluid which contains little vapour or gas, and said inner tubes leading into a dry vapour or gas collecting chamber (112), characterized in that at the bottom of said free volume, the separator has an upwardly convex bottom (110), an annular space (116) for collecting the fluid which has a low vapour or gas content, and passages which are regularly disposed between the vertical tubes (106) and which allow the substantially dry vapour or gas to escape upwards between said vertical tubes (106).

2. A separator according to claim 1, characterized in that the dry vapour or gas collecting chamber (112) is connected by its bottom to a tube (113) for removing the dry vapour or gas, said tube being inclined sideways away from the axis of the separator with a large radius of curvature.

3. A separator according to claims 1 or 2, characterized in that the annular space (116) for collecting fluid with a low vapour or gas content has a small volume and is connected to a receptacle which has a large volume and which collects said fluid, exterior to the separator.

4. A separator according to claims 1 to 3, characterized in that the annular space (116) for collecting fluid with a low vapour or gas content is connected to the collecting receptacle by at least two tubes (117, 118) which are regularly spaced out round its periphery.

5. A separator according to one of the claims 1 to 4, characterized in that it comprises two or more side tubes (120, 121) for removing substantially dry vapour or gas which has escaped upwards between said vertical tubes, said tubes being regularly spaced out round its periphery.

6. A separator according to one of the claims 1 to 5, characterized in that the assembly formed by the inlet chamber (3), the vertical separation tubes (106, 109) and the convex bottom (110) rests by the lower edge of said convex bottom on a ring (123) welded to the outer casing (101, 102) of the separator.

7. A separator according to one of the claims 1 to 6, characterized in that the assembly formed by the inlet chamber and the free volume around the vertical separation tubes is surrounded by an inner casing (15) made of a metal which withstands erosion and corrosion by wet steam which flows at high speed, and is integral with the convex bottom, and in that the outer casing (101, 102) is made of a metal which does not withstand erosion and corrosion by wet steam flowing at high speed.

8. A separator according to one of the claims 1 to 6, characterized in that it includes a single casing (301, 302) which directly surrounds the mixture inlet chamber and the free volume round the tubes (306, 309), and in that the flat bottom plate (304) which separates the inlet chamber from the free volume around the tubes has an upturned rim (26A, 26B) welded to said single casing round at least part (26A) of its periphery.

9. A separator according to claim 8, characterized in that said upturned rim (26A) is welded on the outer casing in the sectors (28) where the vertical tubes (306) are relatively far from the edge of said flat bottom plate (304) and that it remains free (26B) in the sectors (29) where the vertical tubes (306) are relatively close to the edges of said flat bottom plate (304).

10. A separator according to claim 9, characterized in that the gap between the upturned rim (26A, 26B) of the plate and the outer casing (301,302) is covered by resilient sealing strips (30A, 30B) fixed at intervals to said outer casing (301, 302).

11. A separator according to one of the claims 8 to 10, characterized in that the periphery of said flat bottom plate (304) has orifices (31) connected to angle tubes (32) for removing to the outside of the casing any water which may deposit on said plate.

12. A separator according to claim 11, characterized in that said angle tubes (32) have expansion bellows (33) in a vertical portion close to said flat bottom plate.

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