EP0010261A1 - Vertical steam separator-reheater - Google Patents

Abstract

Vertical separator-superheater of steam, comprising in a common shell 1 a lower part of separation 3, and an upper part of superheating 4, with an axial zone of arrival of dry steam, bundles 16, 17 of superheating in distributed envelopes around the central zone, fixed to a thin and flexible ferrule 30 fixed to the top of the ferrule, and an external zone 18 for collecting superheated steam. The lower part includes an annular chamber for the admission of wet steam (5), and separators grouped into two coaxial truncated pyramids (10, 11).

Description

The present invention relates to a vertical vapor separator-superheater comprising, inside a common shell, a lower part forming a separation zone, and an upper part forming a superheating zone, comprising an axial zone for the arrival of dry vapor, 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 French patent application No. 2,406,157, 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 for 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.

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 its lower part comprises an annular chamber for the admission of wet steam, connected to openings for introducing the latter, and separating elements grouped into 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 higher level to 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.

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

The annular passage connecting the annular inlet chamber L 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 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.

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.

Figure 2 shows a diametrical section along the axis II-II of Figure 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 Figure 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 makes it possible to reduce 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 storey 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 evacuated by the axial tube 9.

The separating elements are grouped into 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 pyramid. external. 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 analogous to those described in French patent application No. 2,406,157.

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 shell 1, collect the water and its runoff to the bottom of the shell, above the discharge pipe 9.

The dried steam leaving the separating elements meets on the one hand, in an i ^y ial zone 14A, on the other hand in a peripheral zone 14B. The assembly then rises in the upper overheating part 4.

This overheating part is similar to that described in said patent application and will therefore not be described in detail again. It has 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 ferrule 30, itself welded by its upper edge to the upper bottom 31 of the ferrule.

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 dead angles _z between the rectangular dividers, only two of which have been shown. 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 steam flow rate through the separating elements, but makes it possible to arrange the pipes for introducing wet steam, such as 4A, at any point around the periphery of the shell, so as to reduce the length of the supply piping, and ensures 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 on the periphery of the external pyramid and that of the internal 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 further 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. Vertical vapor separator-superheater, comprising inside a common ferrule (1) a lower part (3) forming a separation zone, and an upper part. ieure (4) forming an overheating zone, comprising an axial zone (15) of dry vapor inlet, tubular bundles (16, 17) of overheating arranged in envelopes distributed around the central zone, and fixed to a thin ferrule and flexible (30) itself fixed to the upper part of the common shell, and a peripheral zone (18) for collecting superheated steam, characterized in that its lower part comprises an annular chamber for the admission of wet steam (5), connected to openings (4A) for introducing the latter, and separating elements grouped in two truncated coaxial pyramids, the external pyramid (10) having its large base at a level lower than that of its small base, and the internal pyramid (11) its large base at a level higher than that of its small base, and the annular chamber etar.t connected by an annular passage (6) to the volume internal to the external pyramid, but external to the internal pyramid . 2. Separator-superheater according to claim 1, characterized in that the annular passage connecting the annular inlet chamber to the volume between the external and internal pyramids comprises a bend at approximately 180 °, delimited on an internal side by offset sheets angularly (7) separated by interstices (7A) allowing a preliminary separation of part of the water contained in the humid vapor, under the effect of centrifugal force. 3. Separator-superheater according to claim 2, characterized in that the interstices of the sheets (7A) are at stepped levels. 4. Separator-superheater according to one of claims 1 to 3, characterized in that members (13A, 13B) for the flow of water stopped in the separator elements are arranged at the edges of the truncated pyramids. 5. Separator-superheater according to one of claims 1 to 4, characterized in that a part of the annular passage is formed by the internal wall (6A) of the bottom of the common ferrule.

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