EP0122544A1

EP0122544A1 - Tube nest support for heat exchangers

Info

Publication number: EP0122544A1
Application number: EP84103758A
Authority: EP
Inventors: Riccardo Belleli
Original assignee: Belleli SpA
Current assignee: Belleli SpA
Priority date: 1983-04-15
Filing date: 1984-04-05
Publication date: 1984-10-24
Also published as: IT1160788B; IT8320630A0

Abstract

The tube nest support comprises a modular grid formed from removably interlocked bars (13, 16, 22, 24...) some of which bearing with their ends on two parallel beams (1, 2) located at the periphery of the tube nest and being connected to the exchanger bearing structure, the bars (e.g. 13) which are located at either ends of each module being hingedly coupled to ear members (e.g. 14,15) welded to the beams (1, 2), the grid mesh size being such as to allow the tubes (3, 4, 5) to pass therethrough in a loose fit relationship.

Description

This invention relates to a tube nest support for heat exchangers.
Plural prior constructional approaches are known in the art to provide supports for the tube nests in heat exchangers, which supports are required to secure the tubes both in the direction of their axes and in a perpendicular plane thereto.
However, none of the solutions proposed heretofore is entirely devoid of disadvantages, brought about by the presence of a large number of welds which are known to cause material distortion, to make fabrication more difficult, and to hinder disassembly where required for maintenance and servicing.
Accordingly, the task of this invention-is to provide a tube nest support for heat exchangers, which has a minimum of welded joints, whereby a good dimensional accuracy can be achieved, and disassembly made simpler and faster without involving replacement of parts upon re-assembly.
Within that task it is an object of the invention to provide a tube nest support, which can attain a high functional efficiency and relieve the stresses exerted by the individual tubes through specially provided members rather than through contiguous tubes.
It is a further object of the invention to provide a tube nest support which can be obtained in a very simple manner.
According to one aspect of the invention, the above task and objects are achieved by a tube nest support for heat exchangers, characterized in that it comprises a modular grid formed from small removably interlocked bars laid in two directions transverse to each other, those of said bars extending in one of said directions in use bearing with their ends onto two parallel beams located at the periphery of the tube nest and being connected in turn to the exchanger load-bearing structure, those bars which are located at either ends of each module being hingedly connected to lugs welded to said beams, the grid mesh size being such as to allow the tubes to pass therethrough in loose fit relationship, the tubes being provided on their outer surface with tooth means designed to rest on the top surface of a respective one of said bars.
Further features and advantages will be apparent from the following description of a preferred, though not exclusive, embodiment of the invention, with reference to the accompanying illustrative drawings, where:

Figure 1 is a schematical plan view of the invention taken at one end of a tube nest;
Figure 2 is a sectional view taken in the plane of the line II-II of Figure 1;
Figure 3 is a detail plan view showing the initial module according to Figure 1;
Figures 4,5,6 and 7 are side views of small bars making up the grid; and
Figure 8 is a plan view of a further bar type provided in the grid.

Making reference to the above views, indicated at 1 and 2 are the two beams located at the periphery of the tube nest comprised of tubes such as those numbered from 3 to 12 and being carried on the first module of the modular grid which will be described in detail hereinafter, and of other tubes carried on further subsequent modules, all identical to one another.
Said first module includes mainly a plurality of small bars laid perpendicularly to the longitudinal axis of the beams 1 and 2, the first of which, indicated at 13 and being shown best in Figure 4, bears at its ends on the beams 1 and 2, and is hinged to the ears 14 and 15, welded to said beams 1 and 2,by the insertion of the bolts 14a and 15a through the holes 13a and slot 13b, respectively, thus allowing for thermal expansion in operation; indicated at 13c and 13d are then two notches at the top side of said bar 13.
A second bar from said plurality in the first module is that indicated at 16 and shown best in Figure 5; this bar is arranged to bear with its ends on the beams 1 and 2, and is hinged to the ears 17 and 18,welded to said beams,by passing the bolts 17a and 18a, respectively, through the hole 16a and slot 16b; further indicated at 16c,16d,16e,16f and 16g are five notches at the bar top side.
The plural bars of the first module, laid perpendicularly to the axes of the beams 1 and 2, are completed by the identical bars 19,20 and 21, only one of which, namely 19, is shown in detail in Figure 6, which bear with their ends on the beams 1 and 2 and are formed with notches at their top sides, similarly to 19a, 19b, 19c, 19d and 19e for the bar 19.
The first module being described also includes a plurality of small bars extending parallel to the longitudinal axes of the beams 1 and 2, at 22 and 23 there being indicated the two end bars laid symmetrically to the longitudinal midaxis of the tube nest. These bars, which are identical to one another, thereby only one of them; 22, is shown in Figure 7, are formed on the bottom side thereof with notches such as 22a,22b,22c,22d and 22e for bar 22, which are adapted to match notches formed in all the bars which are associated therewith: for example, the notch 22a would match the notch 16c in the bar 16, the notch 22b match the notch 19a in the bar 19, and so on, up to the notch 22e which would match the notch 13c in the bar 13, thus engagement holding surfaces are provided binding the various associated bars together both in parallel and perpendicular directions to the longitudinal axes of the beams 1 and 2.
The height of the longitudinal strip unaffected by the notches in the bars 22 and 23 is equal to the depth of the notches in all of the bars in contact therewith, such that, with said bars associated by matching the notches together, all of their top sides will lay in one and the same plane.
The first module is completed by the identical bars 24, 25 and 26, of which only the bar 24 is shown in Figure 8, which have a rectangular cross-section adapted to fit into notches provided in all of the bars associated therewith excepting the bar 13, against which one of the ends is simply brought to abut whereas the other end abuts against the first bar in the adjoining module indicated at 27 in Figure 1 for retention in place; thus, as an example, the bar 24 would be inserted into the notch 16e of the bar 16, the notch 19c of the bar 19, and so on with bars 20 and 21, thus establishing between the associated bars a bond in just the perpendicular direction to the longitudinal axis of the beams 1 and 2.
The depth of the notches accommodating the bars 24,25 and 26 is such that the top side thereof is contained in the plane defined by the top sides of all the bars.
Indicated at 28 and 29 are two sleeve spacers adapted to hold in the right position the bars 16 and 27 which are hinged on the same ears, specifically at one end to the ears 17 and 30 and at the other end to the ears 18 and 31.
The remarkable functional efficiency of the invention is envisaged when considering the manner of taking up the stresses applied by the tubes on the support in the three orthogonal directions in which shifting is prevented or matched by the support itself, and specifically the vertical direction and two directions in the horizontal plane, respectively parallel and perpendicular to the longitudinal axes of the beams 1 and 2.
The downwardly directed vertical forces, which are the ever present and prevailing ones in that they are caused mainly by the tube own weight, are taken up by the teeth formed on the outer surfaces of the tubes bearing on the grid bars, with a uniform distribution which ensures an evenly spread load across the various areas of the grid; thus, for example, the teeth 3a and 4a rigid with the tubes 3 and 4 rest on the bars 21, the teeth 5a and 6a rigid with the tubes 5 and 6 rest on the bars 20, and so on.
The grid stability against upwardly directed vertical seismic actions is ensured by the provision of a crossmember for each module which is carried on ears at a substantially middle location directly overlying the grid; thus, for the first-described module, the crossmember is indicated at 32 and carried on the ears 33 and 34, welded to the beams 1 and 2, respectively. For the module adjoining the first one, the crossmember, not shown in the drawings, would be carried on the ears 35 and 36, etc.
As for the stresses imposed by the individual tubes in both horizontal directions, respectively parallel and perpendicular to the axes of the beams 1 and 2, which, note well, are occasional and of a lesser magnitude than the vertically directed stresses, they being generated essentially by seismic actions or temperature differentials, it is important to observe that they are taken exclusively by the grid bars and transmitted for relieve to the ears welded to the beams 1 and 2, without repercussion from tube to tube.
More in detail, the stresses in a parallel direction to the longitudinal axes of the beams 1 and 2 are taken by the bars 19,20,21, which through the symmetrically arranged bars 22 and 23, discharge the stresses as evenly as possible on the bars 13 and 16 secured to the ears welded to the beams, or are taken directly by said bars 13 and 16; stresses in a perpendicular direction to the axes of the beams 1 and 2 are taken by the bars 22 and 23, which transmit them to the bars secured to the ears 13 and 16, and by the bars 24,25, 26 which again transmit them, either directly or through the bars 19,20,21 and bars 22 and 23, to said bars 13 and 16. It should be finally pointed out that the beams 1 and 2 are secured to the exchanger supporting structure at a substantially centrally located fixed point 1a,2a, thereby thermal expansions may be spread in a symmetrical fashion. Additionally to the functional efficiency, a feature of the invention tobe enhanoed herein is that the welds formed in it are restricted to those for attaching the ears to the beams present at the periphery of the tube nest, all the other elements being merely interlocked by a groove-and-tongue point or threaded together; this enables a high dimensional accuracy and optimum disassembly procedures to be achieved, the same being accomplished by simply withdrawing the individual elements from each other; thus, the operation is a quick one, and involves no deterioration of said elements, which can thus be reassembled without any special provisions as the support is regenerated.
Another important feature of the support of this invention resides in the modularity involving the presence of a number of identical elements which may be readily fabricated in packed forms with few fabricating operations.
The invention described in the foregoing is susceptible to many modifications and variations without departing from the scope of the inventive idea; thus, as an example, the number of plain bars may be different from that indicated, albeit it is bound to be always the largest possible on account of their simplicity.
In practicing the invention, all of the details may be replaced with other, technically equivalent elements; furthermore, the materials used, as well as the shapes and dimensions, may be any ones contingent on requirements.

Claims

1. A tube nest support for heat exchangers, characterized in that it comprises a modular grid formed from small removably interlocked bars (13,16; 22, 24...) laid in two directions transverse to each other, those of said bars extending in one of said directions in use bearing with their ends onto two parallel beams (1, 2) located at the periphery of the tube nest and being connected in turn to the exchanger load-bearing structure, those bars (13,16) which are located at either ends of each module being hingedly connected to lugs (14,15;17,18) welded to said beams (1, 2), the grid mesh size being such as to allow the tubes (3,4, 5,6) to pass therethrough in loose fit relationship, the tubes being provided on their outer surface with tooth means (3a,4a,5a,6a) designed to rest on the top surface of a respective one of said bars.

2. A support according to Claim 1, characterized in that at least two symmetrically arranged bars per module included in the plurality thereof extending along the longitudinal axis of the tearing beams (1,2) have on their bottom sides notches (19a, 19b, 19c, 19d, 19e) adapted to be placed at notches (22a, 22b, 22c, 22d, 22e) provided on the top sides of all the bars coupled therewith, thereby a bilateral bond is established therebetween, all the other bars in said plurality being plain and shaped to have a rectangular cross-section adapted to fit in suitable notches (16c, 16d, 16e, 16f, 16g) provided in the top sides of the bars coupled thereto, thus providing a unidirectional bond.

3. A support according to one or more of the preceding claims, characterized in that the height of the longitudinal strip unaffected by the notches in the notched bars at the bottom sides thereof is substantially equal to the depth of the notches in all the other bars.

4. A support according to one or more of the preceding claims, characterized in that the height of the plain bars cross-section is substantially equal to the depth of the notches (e.g. 22a,16c,22b,19a) wherein said bars are to fit.

5. A support according to one or more of the preceding claims, characterized in that the bars hingedly connected to lugs welded to said beams are coupled to the hinged connection bolts or pins (17a,18a), on one side through a hole (16a), and on the other side through a slot (16b).

6. A support according to one or more of the preceding claims, characterized by the provision in each module of at least one crossmember (32) attached to lugs .(33,34) welded to the bearing beams (1,2) and arranged to lay at a level directly above the plane defined by the top surfaces of the bars comprising said grid.

7. A support according to one or more of the preceding claims, characterized in that the bearing beams (1,2) for the grid-forming bars are secured at a fixed centrally located point (la,2a).

8. A tube mest support for heat exchangers, according to the preceding claims, substantially as herein described and illustrated.