EP0373073B1 - Device for supporting on a stationary frame an overhanging mass connected to a vertically displaceable element - Google Patents

Abstract

A device enabling a mass (1) cantilevered from an element (2) which is vertically moveable under the effect of thermal expansions and contractions to rest against a fixed framework (9). The device comprises a first arm (7) articulated on a point (C) of the vertically moveable element, a second arm (6) articulated firstly to one end (B) of the first arm adjacent to the mass and slidably placed on this junction, and secondly to the fixed framework, and a third arm (8) articulated firstly to one end (2) of the first arm adjacent to the vertically moveable element, and secondly to the fixed framework (9) at a point (D) at a level different from that of the point (E) at which the second articulated arm is articulated thereto. The invention is applicable to the manifolds of boilers or steam generators.

Description

The present invention relates to an arrangement comprising a vertically movable element under the effect of thermal expansions or contractions, and a fixed frame supporting a mass connected in overhang to the movable element, the mass being supported by a device support.

Arrangements of this kind are used in particular in boilers or steam generators, in which frequently appears the problem of the suspension of masses such as manifolds on the walls of combustion chambers whose water circulation tubes to be vaporized undergo. significant expansions and contractions depending on the temperature of the fluid circulating there. These collectors are placed in cantilever with respect to the wall formed by the tubes, and must imperatively follow the movements of this wall without transmitting to it forces liable to deform it.

It has already been proposed to suspend such collectors from spring supports, responsible for taking up part of the weight of the mass in overhang, while being capable of following mass displacements without too great a variation in the force. that they undergo. However, such springs act only as counterweights, and control the vertical position of the mass only at the cost of parasitic forces on the walls of the combustion chamber, all the more important as the force to be taken up by these springs is not constant, since it depends on the forces of variable size, applied by the connecting pipes on the collectors. Furthermore, the manifolds do not remain completely at a fixed point relative to the wall of the combustion chamber.

It has also been proposed to support such collectors by vertical carrier tubes traversed by a fluid which imparts to them a thermal expansion equal to that of the wall of the steam generator. The collectors are then well at a fixed point relative to the wall of the combustion chamber. However, such devices are complex and expensive, and their operation can be disturbed either by a delay in thermal expansion of the vertical carrier tubes relative to that of the wall of the combustion chamber, or by an imperfect circulation of the fluid in the carrier tubes. There is therefore no longer any thermal expansion of the vertical support tubes and of the wall of the combustion chamber, and there may therefore appear unacceptable stresses on the latter.

Finally, it has been proposed in document FR-A-2269023 to have the weight overhang of collectors or burners of combustion chambers by means of lever systems, the pivots of which, integral with a fixed frame, are arranged so that displacements of the support point of the manifold or the burner are equal to the displacements of the attachment point on the wall of the combustion chamber. However, the levers of these systems are subjected to bending, and the accumulation of their bending deformations harms the rigidity of the assembly, unless they are given excessive dimensions.

The object of the present invention is to provide an arrangement ensuring the rigid support of such cantilevered masses, the displacements of which follow more rigorously the displacements of the vertically movable element, composed of elements which are not subjected to flexural stresses, but only tensile or compressive stresses.

The arrangement according to the invention is characterized in that its support device comprises a first arm articulated on a point of the vertically movable element, a second articulated arm, on the one hand on the end of the first arm on the side of the mass, which is placed sliding on the articulation of the first arm and the vertically movable element, on the other hand on the fixed frame, and a third articulated arm, on the one hand on the end of the first arm of the side of the vertically movable element, on the other hand on the fixed frame at a point at a different level from that of the point of articulation of the second articulated arm.

• Le premier et le deuxième bras du dispositif d'appui sont articulés avec possibilité de glissement horizontal sur un support plan lié à la masse, son premier et son troisième bras sont articulés avec possibilité de glissement horizontal sur l'élément mobile verticalement et son deuxième et son troisième bras sont articulés sur la charpente fixe sans possibilité de glissement.
• Le point d'articulation du deuxième bras du dispositif d'appui sur la charpente fixe est à un niveau inférieur à celui de son point d'articulation sur le premier bras.
• Le point d'articulation du premier et du deuxième bras du dispositif d'appui sur la masse est lié à un organe de suspension de cette masse au-dessus de celle-ci et au-dessous des points d'articulation de son troisième bras sur son premier bras et sur la charpente fixe.

It also preferably meets one or other of the following characteristics:

• The first and second arms of the support device are articulated with the possibility of horizontal sliding on a flat support linked to the mass, its first and its third arms are articulated with the possibility of horizontal sliding on the vertically movable element and its second and its third arm are articulated on the fixed frame without the possibility of sliding.
• The articulation point of the second arm of the support device on the fixed frame is at a level lower than that of its articulation point on the first arm.
• The articulation point of the first and second arms of the support device on the mass is linked to a suspension member for this mass above the latter and below the articulation points of its third arm on its first arm and on the fixed frame.

This device may further comprise in each of its variants a support for the mass exerting on it a constant upward traction force.

• La figure 1 représente schématiquement en élévation un arrangement selon une première variante, dans lequel le deuxième et le troisième bras restent sensiblement horizontaux, et sont articulés avec possibilité de glissement comme le premier bras sur le support du collecteur et sur l'écran formé par les tubes de vaporisation et leurs ailettes de jonction.
• La figure 2 représente en élévation un arrangement selon une deuxième variante, dans lequel le deuxième bras fait un angle notable avec l'horizontale, de sorte que le déplacement vertical du point d'articulation sur le support du collecteur est proportionnel à celui du point d'articulation sur l'écran formé par les tubes de vaporisation, et non plus égal à ce dernier. Un support constant du collecteur est en outre relié par un élément de supportage à une charpente fixe au-dessus de lui.
• La figure 3 représente en élévation un arrangement selon une troisième variante, dans lequel le collecteur est suspendu à un point d'articulation, et non au-dessus de celui-ci.

It is described below, by way of examples and with reference to the figures of the appended drawing, arrangements according to the invention with support device on a fixed frame of a vapor collector connected in overhang to the screen formed by the water circulation pipes to be vaporized along the walls of a combustion chamber of a boiler or steam generator.

• Figure 1 shows schematically in elevation an arrangement according to a first variant, in which the second and third arms remain substantially horizontal, and are articulated with the possibility of sliding like the first arm on the support of the collector and on the screen formed by the vaporization tubes and their connecting fins.
• Figure 2 shows in elevation an arrangement according to a second variant, in which the second arm makes a significant angle with the horizontal, so that the vertical displacement of the point of articulation on the support of the collector is proportional to that of the point d articulation on the screen formed by the vaporization tubes, and no longer equal to the latter. Constant support from collector is further connected by a support element to a fixed frame above it.
• Figure 3 shows in elevation an arrangement according to a third variant, in which the collector is suspended from a point of articulation, and not above it.

In FIG. 1, the vapor collector 1 is fixed relative to a partition 2, formed of tubes 2A and connecting fins 2B, of a boiler combustion chamber, so that its connecting tubes 3 with the tubes of a superheater 4 are not subjected to stresses due to differential expansions of the manifold and of the partition.

The collector is fixed on a cross-member 5 pivotally hooked at point A to the partition 2. A second support point of the cross-member is formed by the articulation B, at its other end, on which it is pressed to slide.

The articulation B belongs to a system formed by the articulated arms 6, 7 and 8. The arms 7 and 8 are connected with the possibility of pivoting and sliding at point C, integral with the partition 2, below point A. The arms 6 and 8 are fixed respectively with the possibility of pivoting on the vertical fixed frame 9 at points E and D.

If the wall 2 expands due to its heating, the point C lowers at C 'and the point B at B', the distance B 'C' being kept equal to the distance BC by the arm 7. The vertical projection of segment BB 'is very substantially equal to that of segment CC'. It could even be exactly so, if the quadrilateral BCDE was a parallelogram, which we could obtain by making the segment DE parallel to CB, the point D then no longer being on the vertical of the point E.

2 shows a support device where the arm 6 is inclined relative to the horizontal by an angle α, the other arms being unchanged with respect to Figure 1, so that the vertical displacement of point B, subject to describe a circle of radius BE, that is to say substantially proportional and less than that of point C, and no longer equal to that of the latter. this allows to respond to the fact that during thermal expansions point C of the partition generally descends more than point A. Furthermore, the end of the cross-member 5 is fixed to a constant support element with springs 11, which makes it possible not to dimension the arm system only to support a fraction of the total load, and therefore reduce the vertical load transmitted to the partition 2 formed by the vaporization tubes.

In Figure 3, the manifold 1 is no longer carried by a cross member, but suspended by a fastening member 10 at the point of articulation B.

It is the CD arm which makes an angle α with the horizontal, so that the vertical displacement of point B is still substantially proportional and greater than that of point C.

It will be observed that in all of the above variants, the articulation arms are not subjected to any bending stress, but only to tensile or compression stresses, which makes it possible to give them cross sections significantly less than those of arms of known devices, working in flexion.

The invention applies in particular to the suspension of a manifold on the wall of the combustion chamber of a boiler or of a steam generator but could also be applied to the suspension of other devices, such as burners.

Claims (5)

1. An arrangement comprising an element that is vertically moveable under the effect of thermal expansion or contraction, and a fixed framework (9) supporting a mass (1) cantilevered from the moveable element, the mass being supported by a supporting device, characterized in that said supporting device comprises a first arm (7) articulated on a point (C) of the vertically moveable element, a second arm (6) articulated, on the one hand, to the end (8) of the first arm adjacent to the mass and slidably placed on the articulation of the first arm and the vertically moveable element, and, on the other hand, to the fixed framework, and a third arm (8) articulated, on the one hand, to the end of the first arm adjacent to the vertically moveable element, and, on the other hand, to the fixed framework (9) at a point (D) disposed at a level different from that of the articulation point (E) of the second articulated arm.
2. An arrangement according to claim 1, characterized in that the first arm (7) of the supporting device is articulated, with the possibility of sliding horizontally, on a plane support (5) connected to the mass (1), in that its first and third arms (7, 8) are articulated with the possibility of sliding horizontally, on the vertically moveable element (2), and in that its second and third arms (6, 8) are articulated on the fixed framework without being allowed to slide.
3. An arrangement according to claim 2, characterized in that the articulation point (E) of the second arm of the supporting device on the fixed framework is at a level which is lower than the articulation point (B) on the first arm.
4. An arrangement according to claim 1, characterized in that the articulation point (B) of the first and second arms of the supporting device to the mass is connected to a suspension member (10) for said mass, disposed above said mass and located beneath the articulation points (C, D) of its third arm (8) to its first arm (7) and to the fixed framework (9).
5. An arrangement according to one of claims 1 to 4, characterized in that it further includes a spring support (11) for the mass, said support exerting a constant upwards traction force thereon.

Images