EP0010261B2 - Vertical steam separator-reheater - Google Patents

Description

The present invention relates to a vertical steam separator-superheater, comprising inside a common ferrule a lower part forming a separation zone comprising an annular chamber for the admission of wet steam, connected to openings for introducing this last, and separating elements grouped in stacks separated by at least one gap connected to the annular inlet chamber and of width decreasing from bottom to top, and an upper part forming an overheating zone, comprising an axial zone of arrival of dry steam, tubular bundles of overheating arranged in envelopes distributed around the central zone, and fixed to a thin and flexible ferrule itself fixed to the upper part of the common ferrule, and a peripheral zone for collecting superheated steam .

A separator-superheater of this kind, described in the intermediate document FR-A 2406157, makes it possible to absorb the expansions and contractions of the superheater bundles without special device such as expansion lyres, and facilitates the possible extraction of these bundles in view of their repair. The arrangement of the separator elements grouped in several parallel rows of V-shaped stacks, however, makes it less easy to access the internal walls of the lower zone of the separator-superheater, and it also imposes the orientation of the access pipes. wet steam to be treated, since this must arrive symmetrically with respect to the rows of stacks of separating elements.

An arrangement of the separating elements in the form of a truncated pyramid is known from the document FR-A 2187 394. The mixture is admitted by a chamber located below the pyramid, which increases the height of the apparatus. This disadvantage of an excessive height is also present in the device according to document FR-A 2140391, since there is provided between two stages of separation an inlet chamber for the mixture. This chamber is crossed concentrically by the tube connecting the two stages.

The object of the present invention is to provide a separator-superheater which allows excellent accessibility to all the internal walls of the lower zone ensuring the separation function, and whose access pipes of the steam to be treated can have any orientation. It also aims to provide a set of separating elements in which the bodies for discharging the stopped water occupy a very small place.

The separator-superheater according to the present invention is characterized in that the separator elements are grouped in two truncated coaxial pyramids, the external pyramid having its large base at a level lower than that of its small base, and the internal pyramid its large base at a level higher than that of its small base, and the annular chamber being connected by an annular passage to the volume internal to the external pyramid, but external to the internal pyramid.

• Le passage annulaire reliant la chambre annulaire d'admission au volume compris entre les pyramides externe et interne comporte un coude à 180° environ, délimité sur un côté intérieur par des tôles séparées par des interstices permettant une séparation préliminaire d'une partie de l'eau contenue dans la vapeur humide, sous l'effet de la force centrifuge.

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

• The annular passage connecting the annular admission chamber to the volume between the external and internal pyramids comprises a bend at approximately 180 °, delimited on an internal side by sheets separated by interstices allowing a preliminary separation of a part of the water contained in moist steam, under the effect of centrifugal force.

Flow devices for the water stopped in the separating elements are arranged at the edges of the truncated pyramids.

Part of the annular passage is formed by the internal wall of the bottom of the common ferrule.

• La figure 1 représente une coupe axiale selon l'axe I-I de la figure 2 un séparateur-surchauffeur dans lequel le passage annulaire d'introduction de la vapeur humide vers les éléments surchauffeurs descend jusqu'au voisinage du fond de la virole, une partie de ce fond constituant une paroi du passage.
• La figure 2 représente une coupe diamétrale selon l'axe II-II de la figure 1.
• La figure 3 représente en coupe axiale un autre séparateur-surchauffeur dans lequel le passage annulaire d'introduction de la vapeur humide est au-dessus du fond de la virole.

It is described below, by way of examples and with reference to the figures of the appended drawing, two steam separator-superheaters according to the invention.

• FIG. 1 represents an axial section along axis II of FIG. 2 a separator-superheater in which the annular passage for the introduction of wet steam to the superheater elements descends to the vicinity of the bottom of the shell, part of this bottom constituting a wall of the passage.
• FIG. 2 represents a diametrical section along the axis II-II of FIG. 1.
• Figure 3 shows in axial section another separator-superheater in which the annular passage for the introduction of wet steam is above the bottom of the shell.

The separator-superheater of FIG. 1 comprises, inside a cylindrical shell 1, supported by a usual annular support by a floor 2, a lower part 3 (forming a separator) and an upper part 4 (forming a superheater) . The lower part is fitted with 4A pipes for supplying wet steam. These open into an annular chamber 5 connected to an annular passage 6 for access to the separating elements, forming a 180 ° bend. Part of the internal wall of this passage is formed by the wall 6A of the bottom of the shell. This reduces the total height of the separating part 3, but requires that the wall 6A be coated with stainless steel, like the rest of the passage wall, in order to avoid the phenomenon of erosion-corrosion by wet steam. at high speed. The other part of the external wall of the passage consists of sheets 7 angularly offset with respect to the vertical axis and separated by interstices 7A at stepped levels, ensuring a preliminary separation of the water droplets under the effect of the centrifugal force resulting from the change in direction of the vapor. The water separated on the sheets 7 and flowing through the interstices 7A collects in the bottom 8 with the water retained in the separating elements, as will be indicated below, and is discharged through the axial tube 9.

The separating elements are grouped in two truncated pyramids with an octagonal base, the external pyramid 10 having its large base downwards, and the internal pyramid 11 with its large base upwards, the latter being substantially in contact with the small base of the external pyramid. It therefore appears between the two pyramids an annular gap 12, of decreasing width upwards, for the access of the wet steam to the separating elements. These are similar to those described in the intermediate document FR-A 2406157.

The pyramids of separating elements are provided along their external edges with elements for discharging separate water, such as 13A for the external pyramid and 13B for the internal pyramid. Vertical sheets 29, then inclined towards the axis of the ferrule 1, collect the water and its runoff to the bottom of the vi role, above the discharge pipe 9.

The dried steam leaving the separating elements meets on the one hand, in an axial zone 14A, on the other hand in a peripheral zone 14B. The assembly then rises through an intermediate zone 13 towards the upper overheating part 4.

This overheating part is similar to that described in the intermediate document FR-A 2406157 and will therefore not be described in detail again. It comprises an axial zone 15, around which are arranged four superheater bundles such as 16, 17. These are fixed to the internal surface of a thin shell 30, itself welded by its upper edge to the upper bottom 31 of the ferrule. The dried steam therefore rises towards the axial zone 15, then radially crosses the bundles while overheating and reaches an outlet pipe 19 through a peripheral zone 18 for collecting the superheated steam.

The superheater bundles are supplied with high pressure steam via the pipe 20, the O-manifold 21 and the connections 22 connected to the end chambers 23. The high pressure steam condensed mainly in the tubular bundles such as 16, 17 and arriving in the end chambers 24, are collected in the collector 25, then sent via the conduit 26 to the recipe pot 27.

FIG. 2 shows more precisely the arrangement of the separate water collection members, such as 13A, 13B, respectively at the edges of the outer and inner pyramids of the stacks of separating elements, therefore in the blind spots between the rectangular separators , only two of which have been represented. This arrangement allows the useful volume offered to be reduced only to a small extent, while ensuring satisfactory flow of the separated water. We see a separator 32 of the external truncated pyramid, and a separator 33 of the internal truncated pyramid. It can also be seen that the separator system is symmetrical with respect to the vertical axis of the shell. This has the disadvantage of a slight asymmetry in the flow of steam through the separating elements, but makes it possible to arrange the pipes for introducing wet steam, such as 4A, at any point on the periphery of the shell, so as to reduce the length of the supply piping, and ensures a circulation of the dried steam symmetrical with respect to the vertical axis, as well as excellent accessibility to all the walls for their inspection and possible repairs both around the perimeter of the outer pyramid than on that of the inner pyramid.

FIG. 3 represents a separator-superheater similar to that of FIGS. 1 and 2, but in which the passage 6 of the wet steam from the inlet pipes to the separating elements is more distant from the bottom of the shell. The identical members will therefore not be described again. In this case, it is not necessary to have an internal coating of stainless steel on the bottom part of the shell in contact with the incoming wet vapor. The passage 6 always prints a 180 ° bend with wet steam, which allows a preliminary separation of the water droplets on the sheets 7 delimiting the passage, with evacuation of the water by the interstices 7A between these sheets.

The number of sides of the truncated pyramids formed by the stacks of separators can be less than or greater than eight. It is possible to provide for a partial withdrawal of dried steam before it is introduced into the overheating zone.

Claims (5)

1. A vertical steam separator-superheater comprising within a common casing (1) a lower portion (3) forming a separation zone and including an annular wet steam inlet chamber (5) connected to wet steam inlet openings (4A) of the latter, and separator elements (11) grouped in piles separated by at least one interval (12) connected to the annular inlet chamber and having a width which decreases from the bottom to the top, the said separator-superheater further comprising an upper portion (4) forming a superheating zone including an axial dry steam inlet zone (15), nests (16, 17) of superheating tubes disposed in envelopes spaced out round the central zone and fixed to a thin and flexible casing (30), said thin and flexible casing itself being fixed to the upper portion of the common casing and defining a peripheral superheated steam collection zone (18), characterized in that the separator components are grouped in two coaxial truncated pyramids, the outer pyramid (10) having its large base lower than its small base and the inner pyramid (11) having its large base higher than its small base, and wherein said annular inlet chamber communicates via an annular passage (6) with the volume contained between the outer pyramid and the inner pyramid.

2. A separator-superheater according to claim 1, characterized in that the annular passage which connects the annular chamber with the volume between the outer pyramid and the inner pyramid bends about 180° and is delimited on an inner side by angularly shifted metal sheets (7) separated by interstices (7A) which allow preliminary separation by centrifugal force of part of the water contained in the wet steam.

3. A separator-superheater according to claim 2, characterized in that the interstices (7A) of the metal sheets are disposed at graduated levels.

4. A separator-superheater according to claim 1, characterized in that units (13A, 13B) for allowing the water collected in the separator components to flow are disposed at the ridges of the truncated pyramids.

5. A separator-superheater according to claim 1, characterized in that part of the annular passage is formed by the inner wall (6A) of the bottom of the common casing.

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