FR2766233A1 - WATERPROOF DEVICE FOR THE CONNECTION BETWEEN THE STEAM INLET AND THE INTERNAL BODY OF THE LOW-PRESSURE ASSEMBLY OF A STEAM TURBINE - Google Patents

Abstract

The present invention relates to a sealed device for the connection between the steam inlet duct (10) and the internal body (7) of the low pressure stage of a steam turbine. The connection between the steam inlet duct (10) and the casing (1) of the exhaust box is made by means of a deformable tubular element (15), the upper end of which is integral with the exhaust box of the low-pressure body and the lower end of which is integral with a connecting flange of the steam inlet duct (10) with the low-pressure body (7).

Description

SEALED DEVICE FOR CONNECTION

  BETWEEN THE STEAM INLET AND THE INTERNAL BODY

  OF THE LOW-PRESSURE ASSEMBLY OF A STEAM TURBINE.

  The present invention relates to the field of steam turbines, and more precisely the connection between the steam inlet duct and the

  low pressure body of a steam turbine.

  The low-pressure module is made up of two independent assemblies: - an external casing connected to the condenser sleeve and resistant to atmospheric pressure. This envelope is carried by the massif and does not have a hot part; - an internal body with two symmetrical flows enclosing the vapor stream. It carries low pressure diaphragms. A piping connects the medium pressure part to the low pressure part. This piping

  leads to the arrival of steam from the internal body.

  The differences in temperature cause expansions whose amplitude can reach several centimeters. It is therefore necessary to ensure the connection between the steam inlet duct and the low-pressure body with means of

compensation.

  The connection is usually made by a compensator which cannot be reached for the

  disassembly only from the inside of the lower part-

  pressure. This requires disassembly of several elements of this assembly, and results in a heavy intervention immobilizing the turbine for a

important time.

  The object of the present invention is to remedy this drawback by proposing a connection device that can be easily removed from the outside of

  the turbine, and a lower manufacturing cost.

  To this end, the invention relates in its most general sense to a device of the type constituted by a module capable of being mounted on the low-pressure outer casing, and incorporating a compensator capable of absorbing the displacements of the end of the inlet sheath, characterized in that the connection between the sheath and the low-pressure outer box is produced by means of a deformable tubular element, the upper end of which is integral with the exhaust box and whose l lower end is secured to a connecting flange of the inlet sheath

  of steam with the low-pressure body.

  Advantageously, the deformable tubular element consists of a wavy shaped sleeve

bellows.

  According to a preferred variant embodiment, the exhaust box comprises an annular crown with an inside diameter substantially greater than the outside diameter of the steam inlet duct, said crown having bores allowing the attachment of a complementary crown integral with '' deformable tubular elements by means of bolts accessible from the outside of the enclosure

the low-pressure stage.

  Advantageously, the deformable tubular element is fixed at its lower part to the flange surrounding the low-pressure body by means of an inner ring connected to said flange by bolts accessible from outside the envelope of the

low pressure module.

  Preferably, the outer surface of the steam inlet duct and the inner surface of the deformable cylindrical element delimits an annular space at the bottom of which is located the lower ring for fixing the tubular element to the

low pressure body.

  According to an advantageous variant, the device comprises an annular protective plate closing off the space remaining between the complementary crown fixed to the upper end of the deformable element, and the wall of the inlet sheath

steam.

  According to another alternative embodiment, the deformable tubular element is extended by a

length adjustment ferrule.

  According to another advantageous variant, the deformable tubular element is protected by an external rigid tubular plate of a length greater than the length of the deformable tubular element. The invention will be better understood on

  reading of the description which follows, referring to

  annexed drawings relating to nonlimiting exemplary embodiments o: - Figure 1 shows an overview of the low-pressure module; - Figure 2 shows an exploded view in three dimensions of a device according to the invention; - Figure 3 shows a detailed view of the connection of the sleeve with the fixing ring - Figure 4 shows a detailed view

  fixing the lower part of the sleeve.

  Figure 1 shows a cross-sectional view of a low pressure module. This module is constituted by an upper external envelope (1) and by a lower external envelope (2). The external envelope is made of welded sheets. It is internally stiffened by ribs (3) and is braced by round bars (4) arranged in a lattice. The lower part of this envelope (2) is supported on the block (5) by a sole (6) reinforced by gussets. This design of the external structure makes it possible to obtain a good distribution of the loads on the massif. The internal body (7) made of welded construction rests on the lower part of the envelope at the level of the lateral flanges (8) of its horizontal joint. The admission area is limited by

an annular chamber (9).

  The steam comes from the medium pressure stage through a pipe (10). This piping is connected via a spacer (11) to the body vapor inlet. Given the effects of expansion of the piping, this spacer (11) is capable of moving both transversely and vertically. To absorb these displacements, a compensator (12) is provided between the upper envelope (1) of the external box, and the spacer (11). This compensator also fulfills

sealing functions.

  It is described in more detail in the

description which follows.

  The steam supply passes through the envelope (1) at a hole whose section is substantially greater than the outside section of the inlet. The difference in section allows sufficient lateral play to absorb the various displacements resulting from the forces transmitted by the pipes of

  steam (10) due to expansion phenomena.

  This inlet is connected to the intake section (13) of the internal body by a flange

exterior (14).

  The seal is ensured by an elastically deformable sleeve (15) made of stainless steel or

  a similar material, having a bellows shape.

  This sleeve (15) surrounds the lower end (16) of the sheath (10). The upper part (17) of the sleeve (15) is welded to an outer ring (18) of annular shape and having an internal section corresponding to the external section of the part

upper (17) of the sleeve (15).

  This outer ring (18) is bolted to a complementary ring (20) welded to the outer casing (1). A seal (21)

  is interposed between the two crowns (18, 20).

  The lower end (23) of the sleeve (15) is extended by a tubular ferrule (24). This ferrule makes it possible to adjust the length of the device at the time of assembly of the turbine, and to make up for misalignment by cutting this ferrule.

ring at ad-hoc height.

  The end of this ferrule is welded to an annular plate (26) ensuring the connection with an inner ring (27) whose external diameter is at most equal to the internal diameter of the ferrule and the sleeve (15), and whose diameter interior is at most

  equal to the outside diameter of the steam supply.

  This ring (27) forms a spacer coming to be positioned between the two parts (28, 29) of the sheath connecting flange (10) on the body (13). Seals (30, 31) seal between the crown (27) and the two parts (28, 29) of the flange. Bolts (32) secure the assembly. These bolts are accessible from the outside, through the annular space (33) delimited by the outer wall of the sheath (10) and the inner wall of the sleeve (15), and opening by the cutout (12) of the outer casing (1). It is thus possible to disassemble the inlet from the outside of the turbine, without

  have to remove the outer casing (1).

  The sleeve (15) is protected by two tubular plates (34, 35) surrounding the outer surface and the inner surface of the sleeve. At least one of these plates (34, 35) has a length greater than the length of the sleeve (15), in order to avoid damage to the lower surface of the sleeve when it is placed on the ground. Furthermore, these tubular plates protect the surface of the sleeve (15) against shocks likely to occur during handling, especially during the phases of

assembly or disassembly.

  To prevent tools from falling into the hollow space (33), a protective plate (36) closes the gap between the outer wall of the sheath (10) and the crown (18). This plate has an interior cut adapted to allow the

  transverse displacement of the sheath (10).

  Figure 3 shows a detailed view of the

  connection of the sleeve with the fixing crown.

  The sleeve (15) is welded to the internal edge (40) of the crown, as is the edge

  upper of the internal protection plate (34).

  This protective plate has a tubular shape, with a flared upper part (41). The outer plate (35) is welded to the surface

  lower (42) of the crown (18).

  Figure 4 shows a detailed view of

  fixing the lower part of the sleeve (15).

  The first part (28) of the fixing flange is welded to the outer wall of the steam inlet duct (10) by two weld beads (50, 51). Likewise, the second part (29) of the flange is welded to the inlet (13) of the low pressure body.

  by two weld beads (52, 53).

  The crown (27) is welded to the connection plate (26). The crown (27) is bolted to the lower part (29) of the flange by bolts, the head of which is pressed into a cavity (55) to avoid flush with the surface of the crown (27). The upper part (28) of the flange is bolted to the crown (27) forming a spacer between the two

parts of the flange.

  For disassembly, access to the bolts ensuring the connection between the upper part (28) of the flange and the crown (27) after removing the protective plate (36) closing the tubular space (33) provided between the outer wall sheath (10)

  and the inner wall of the compensation device.

  This space is wide enough to allow the passage of a tool allowing the unscrewing of the bolts

and releasing the sheath (10).

  After removing the sheath (10), you access the bolts ensuring the connection between the

  crown (27) and the lower part (29) of the flange.

  We also unscrew the bolts ensuring the connection between the upper crown (18) and the outer casing (1). We can then remove the

  compensation by removing it vertically.

Claims (5)

  1 - Watertight device for the connection between the steam inlet duct (10) and the internal body (7) of the low pressure assembly of a steam turbine, of the type constituted by a module suitable for being mounted on the low pressure external jacket, and incorporating a means suitable for absorbing the displacements of the end of the inlet duct, characterized in that the connection between the steam inlet duct (10) and the jacket (1 ) of the exhaust box is produced by means of a deformable tubular element (15) whose upper end is secured to the low-pressure exhaust box and whose lower end is secured to a flange connecting the steam inlet duct (10) with the low-pressure body (7).   2 - Device according to claim 1 characterized in that the deformable tubular element (15) consists of a corrugated sleeve in the form of a bellows. 3 - Device according to claim 1 or 2 characterized in that the exhaust box comprises an annular ring with an inside diameter substantially greater than the outside diameter of the steam inlet duct (10), said ring having bores allowing fixing a complementary crown integral with the deformable tubular element (15) by means of bolts accessible from the outside of the low-pressure envelope. 4 Device according to any one of   previous claims characterized in that   the deformable tubular element (15) is fixed at its lower part to the flange surrounding the low-pressure body by means of an inner ring connected to said flange by bolts   accessible from outside the bass enclosure   pressure. - Device according to at least one of   claims 3 to 4 characterized in that the surface   outside of the steam inlet duct (10) and the inside surface of the deformable cylindrical element delimits an annular space at the bottom of which is the lower element fixing ring   tubular on the low-pressure body.   6 - Device according to at least one of   Claims 3 to 5 characterized in that it comprises   an annular protective plate closing off the space remaining between the complementary crown fixed to the upper end of the deformable element, and the   wall of the steam inlet duct (10).   7 - Device according to any one of   previous claims characterized in that   the deformable tubular element (15) is extended by   a length adjustment ferrule.   8 - Device according to any one of   previous claims characterized in that   the deformable tubular element (15) is protected by an external rigid tubular plate of a length greater than the length of the tubular element deformable (15).