DESCRIPTION

The present invention relates - in general - to the field of boilers and relates to a boiler comprising a joint for decoupling the thermomechanical stresses applied to a component inside the boiler with respect to a wall of the boiler itself and with respect to the external environment with respect to the wall.

Background

The context thereto the invention relates - in general - is the one of the thermal systems for the production of Energy such as HRSG (Heat recovery steam generator) and more generally to any heat exchanger.

In this description, for sake of simplicity the term ‘boiler’ will be used to designate any closed container, inside thereof there is a different (typically higher) temperature than the external environment.

Under determined circumstances, it becomes important to monitor and control the thermomechanical stresses acting on the internal components of the boilers.

In fact, for example due to the high thermal excursions between the inside and the outside of the boiler and/or between the downtime moments and the activity ones of the boiler itself, or after produced thermal gradients, the internal- typically metallic - components are strongly subjected to deformations and/or movements in space.

Under these circumstances there may be the need for compensating in some way these deformations or movements to avoid other constrained or correlated components from being damaged.

For example, the case may happen in which measurement probes have to be arranged on the internal components of the boiler (for monitoring in real time specific parameters). Such probes, typically, should be connected physically to the outside of the boiler and then in some way they have to cross the wall.

Under these circumstances, each position variation between the internal component and the boiler wall and the outside of the boiler itself then may be the cause of rupture of the probes and may cause the malfunction thereof. This problem is much more felt if the probes are implemented through sensors made of optical fibre, particularly delicate and fragile.

Technical problem solved by the invention

The object of the present invention then is to solve at least partially one or more of the problems left unsolved by the known art.

The solution according to the present invention inserts in this context, which solution proposes to provide a boiler equipped with a joint for decoupling between the thermomechanical stresses applied to an internal component of a boiler and a wall of the boiler itself as defined in the independent claim 1.

Additional features of the present invention are defined in the corresponding depending claims.

The main advantage of a device according to the present invention is that its use makes that no compressive or tensive effort is created in the main three axes between the internal component of the boiler (for example a collector) and the boiler wall.

Moreover, such technical advantage is implemented by guaranteeing at the same time both an effective condition of thermal insulation between an internal portion of the boiler and the environment outside it, and a condition of confinement of the hot gases existing inside the boiler itself.

A joint according to the present invention results to be cost-effective and advantageous to be implemented and applied industrially. It occupies little space inside the boiler chamber, by making simpler and more effective both the installation and the use thereof and creating fewer constraints of structural sizing of other portions proximal thereto.

Moreover, such joint results to be easily replaceable in case of failure or rupture thanks to its planar structure and additionally according to possible embodiments with eased quick opening.

Additionally, thanks to the technical features of a device implemented according to the present invention it may move according to motions of pure translations according to carriers related to a plane of a boiler wall whereas the possible granted rotations are only those produced around a rotation axis perpendicular to said plane of said boiler wall.

In other words, in this way it is possible to guide the motions of the device by minimizing stresses and by limiting selectively the spatial orientations of the device itself after the possible thermal gradients which have generated inside the boiler, thus allowing a more effective control of its arrangement in space and by reducing the possibility of inducing mechanical deformations or collisions on other portions or devices connected thereto.

Other advantages, together with the features and the use modes of the present invention, will result evident from the following detailed description of preferred embodiments thereof, shown by way of example and not for limiting purposes.

An additional advantage of the proposed solution is the capability of not transferring any thermomechanical effort by preserving the thermal insulating capabilities and against gases of the wall of the boiler itself.

Brief description of figures

The drawings shown in the enclosed figures will be referred to hereinafter in this description, wherein:

• figure 1 is a partial schematic section view of a boiler incorporating a joint according to a possible embodiment of the present invention;

• figure 2 is a possible variant of the embodiment of figure 1 ;

• figures 3 and 4 are possible variants of the embodiments of figures 1 and 2, respectively;

• figure 5 is a partial schematic section view of a boiler incorporating a joint according to a further possible embodiment of the present invention;

• figure 6 is a partial schematic section view of a boiler incorporating a joint according to a still further possible embodiment of the present invention. Detailed description of preferred embodiments

The present invention will be described hereinafter by making reference to the above-mentioned figures. In particular, figure 1 shows, schematically and by way of example, a boiler cross portion.

In particular, with respect to the boiler wall 20, the side identified with A represents the boiler inside in which there is a boiler component 10, whereas the side identified with B represents the boiler outside.

In particular, according to the invention, a joint 1 is provided for decoupling between the thermomechanical stresses applied to the component 10 inside the boiler and a boiler wall 20. Such stresses are mainly due to the effect of temperature variations between the various portions of the boiler itself and/or between downtime periods and activity periods of the boiler and they exteriorize in dilatations and/or movements in the space of the internal component 10 with respect to the wall 20.

Such movements can be of pure translation along the three axes X, Y, Z of the designated reference system, as well as of rotation, for example due to torsions. It is interesting to note that thanks to preferred technical features of the present invention the granted rotations are only those produced around a rotation axis parallel to the longitudinal axis X, whereas the rotations around an axis perpendicular to the longitudinal axis X are inhibited or annulled.

The boiler wall 20 usually comprises an internal wall 21, a cavity 23 and an external wall 22.

The cavity 23 preferably is filled-in, at least partially, with insulating material.

As already explained above, the present invention relates to the circumstances under which there is an additional mechanical connecting element between the internal component 10 and the wall 20 which has to go out from the boiler wall, for example probes for measuring the temperature (or other parameters).

Then the boiler wall 20 necessarily has to provide for a wall hole 25.

This connecting element would clearly undergo the stresses thereto the internal component 10 is subjected and, should it be an element with stiff connection with the wall itself, would clearly risk to be damaged due to the relative movements between component 10 and wall 20. Then, according to the invention, the joint 1 preferably comprises a tubular element 2 apt to be made integral with the component 10 and apt to pass through the wall 20 through the wall hole 25.

Within the present description, under the term “tubular element” an element having a substantially elongated shape has to be meant, which can be hollow or not and which has a cross section with any (regular or not) shape. Preferably, it is meant that the section of the tubular element is constant at least in the element tract involving directly the connection with the other joint components.

The modes therewith the tubular element 2 can be made integral with the component 10 can be the most various ones, for example through welding or fixing with screws and/or bolts.

It is to be meant that such modes are within the comprehension of the average person skilled in the art and then it is not considered necessary to provide a detailed description thereof.

Advantageously, the tubular element 2 will have a cross section with lower extension than the extension of said wall hole 25.

In the specific case, the difference between the area of the section of the tubular element 2 and the extension of the wall hole 25 will be so as to contain the translation movements along the axes Y and Z of the tubular element 2 (when this is integral with the component 10).

Inside the wall 20, at the tubular element 2, an insulating element 4 can advantageously be provided, for example a monolayer or multilayer ceramic “bolster” insulating cushion, surrounding the tubular element 2 and fills-in, at least partially, the portion of cavity 23 at the wall hole 25, at least for a greater width than the extension of the wall hole 25.

According to a possible embodiment, the insulating element 4 can even include a pair of plates 6, an internal one and an external one therebetween monolayer or multilayer insulating sheets of ceramic type, for example, are housed preferably for applications with high temperatures, “superwool blanket” with density of 128Kg\m ³ . Alternative forms of insulating solutions are glass wool-based materials or similar technical solutions. Preferably, the insulating element 4 is slidingly arranged around said tubular element 2, so as to allow the relative sliding of the tubular element 2 in case of translation movements along the axis X.

According to the invention, the joint 1 further comprises an inner plate 3 arranged between the internal component 10 and the internal wall 21, in abutment to the internal wall 21 , to close the wall hole 25.

The inner plate 3 has an inlet hole 3’ having a shape substantially coinciding with the cross section of the tubular element 2, which is slidingly inserted in the inlet hole 3’ so that the relative sliding of the tubular element 2 is allowed in case of translation movements along the axis X.

Preferably, the inner plate 3 is kept in abutment to the internal wall 21, however by preserving the sliding capacity of the same on the internal wall 21 in case of translatory movements of the tubular element 2 along the directions Y and Z. To this purpose first holding means 5 is provided. According to an embodiment, the first holding means 5 is implemented in the shape of one or more elastically deformable elements, for example of clips, apt to be fixed to the internal wall 21 so as to apply their elastic reaction to the inner plate 3, holding it in abutment to the internal wall 21.

According to an alternative embodiment, shown in figure 2, the first holding means 5 is implemented in the shape of one or more magnetic elements apt to be interposed between the inner plate 3 and the internal wall 21, so as to maintain the inner plate 3 in abutment to the internal wall 21.

The inner plate 3 substantially acts as insulating element, it is sliding on the tubular element and allows to insulate the environment inside the high-temperature boiler effectively (by locking even the transit of hot gases) by increasing and thus by guaranteeing a high thermal gradient between the portion inside the boiler and the portion outside it.

Additionally to what described above, a joint according to the invention can further include an external plate 8, thus creating additional embodiments, illustrated by way of example in the subsequent figures 3 and 4. The external plate 8 has an outlet hole 8’ having a shape substantially coinciding with the cross section of said tubular element 2, so that the tubular element 2 could be slidingly inserted in the outlet hole 8’.

The external plate (8) is arranged outside the external wall 22, in abutment to the external wall 22.

Similarly to what already described in relation to the inner plate 3, even the external plate 8 is preferably kept in abutment to the external portion 22, while allowing the relative sliding thereof along the axes Y and Z.

To this purpose, the joint then can provide second holding means 5’, for keeping the external plate 8 in abutment to the external wall 22, allowing it to slide anyway.

According to some embodiments, the second holding means 5’ comprises one or more elastic elements, for example clips, apt to be fixed to the external wall 22 so as to apply their elastic reaction to the external plate 8, holding it in abutment to the external wall 22.

According to other embodiments, the second holding means 5’ comprises one or more magnetic elements apt to be interposed between the external plate 8 and the external wall 22 so as to maintain the external plate 8 in abutment to the external wall 22.

It is to be meant that among the different possible embodiments, even embodiments - although not explicitly described - may be provided wherein the first and the second holding means are mixed, partially elastic and partially magnetic means.

By making now reference to the subsequent 5, to each one of the joint embodiments deriving from what described sofar, a textile joint 50, may be associated, insulated too preferably for example with “superwool blanket” insulating sheets or with Bolster, arranged outside the external wall 22, between said external wall 22 and said tubular element 2.

It is not considered necessary to go into details about the implementation of textile joint, since it is a component known to the person skilled in the art.

It is to be meant that, although illustrated and described in relation to one of the possible embodiments, the textile joint 50 may be applied to each one of the embodiments explicitly or implicitly provided by this description. By making now reference to figure 6, an additional variant is illustrated, applicable too to each one of the embodiments explicitly or implicitly provided by this description.

In particular, such variant provides that the joint further comprises one or more guiding tubes 30, integral with the tubular element 2, and slidingly assembled on the provided joint components: inner plate 3 and/or insulating element 4 and/or external plate 8.

These guiding tubes could advantageously be used to bring outside the boiler delicate and fragile elements, such as for example measuring optical fibres, probes or other so that a condition is created for decoupling the thermomechanical stresses producible inside the boiler.

According to an alternative embodiment of the invention it is possible to provide even a decoupling joint allowing rotations along an axis perpendicular to said longitudinal axis X and inhibiting the pure translations along the axes of the plane Y and Z.

In this case the main differences with respect to what previously described can be found in presence of a curved inner plate 3 following the curved path of a reference internal wall or of a middle portion constrained on a flat wall with the purpose of reproducing the possibility of rotational movements around an axis perpendicular to longitudinal axis X even in case there is an internal wall of a curved boiler by guaranteeing at the same time the thermal and fluid-dynamic insulation between the internal portion and the external one of the boiler.

The present invention has been sofar described with reference to preferred embodiments thereof. It is to be meant that each one of the technical solutions implemented in the preferred embodiments, herein described by way of example, can advantageously be combined, differently from what described, with the other ones, to create additional embodiments, belonging to the same inventive core and however all within the protective scope of the herebelow reported claims.