WO2008006324A1

WO2008006324A1 - Air-cooled installation comprising incorporated elastomer damping layers

Info

Publication number: WO2008006324A1
Application number: PCT/DE2007/000501
Authority: WO
Inventors: Heinz-Dieter Bensing; Alexander Scholz; Georgios Samolis
Original assignee: Gea Energietechnik Gmbh
Priority date: 2006-07-07
Filing date: 2007-03-20
Publication date: 2008-01-17
Also published as: DE102006031830B4; DE102006031830A1

Abstract

The invention relates to an air-cooled installation comprising heat exchanger elements on a load-bearing support, said support having several vertical stanchions (3) and coupling struts (4) that interconnect the stanchions (3). At least one coupling strut (4) is connected to the stanchion (3) with the incoroporation of a damping layer (10), in order to reduce wind-induced vibrations of the coupling struts (4).

Description

AIR-COOLED SYSTEM WITH INTEGRATED ELASTOMERS

DAMPING BASES

19.03.2007 XG / Dk

Our sign: GEA1352WO

The invention relates to an air-cooled plant with the features in the preamble of patent claim 1.

Air-cooled systems are used e.g. used in the form of condensation plants for cooling turbines or process vapors and are in energy technology in very large dimensions for many years in use. In known designs, fans suck in cooling air from below and press them through roof-shaped heat exchanger elements. The heated cooling air flows upwards. There must be sufficient free space below the fans, so that the fans are arranged, for example, at a height of 20 m on a load-bearing scaffold. The scaffold is a steel construction of columns and the connecting rods connecting the columns. The coupling rods are required because the supports are relatively slim and would reach a non-permissible buckling length without transverse support. The coupling rods also serve to remove the horizontal forces caused by wind and earthquake in the foundations.

It has been shown that the coupling rods can be set in vibration by the oncoming wind, even at relatively low wind speeds of 4 to 5 m / s. Coupling rods such systems have lengths of over 10 m and z. B. made of tubes with about 220 mm diameter. I-profiles are also used. Due to the considerable length, such a coupling rod can weigh several 100 kg have, so that there is considerable stress in the connection region of the coupling rods when the coupling rods are set in vibration.

In tests with a longitudinally welded tube with a diameter of 220 mm, it was found that deflections of +/- 15 mm can occur in the middle region of the coupling rod. It is to be expected that such large amplitudes permanently lead to fatigue fractures in the connection area. The vibration excitation is primarily due to a uniform wind-induced flow of the coupling rods, which can cause transversely to the flow direction oscillations of the coupling rods due to regular vortex shedding (Karman vortex street). If the vortex shedding frequency encounters a component natural frequency, this can lead to a pronounced resonance oscillation of the coupling rods.

The vibration behavior depends on the damping capacity of the steel structure. In the new DIN 1055, part 4, Annex F specifies a logarithmic attenuation decrement for different types of structures. For structures in steel construction, the damping decrement should have a minimum value of δ = 0.05. This value applies to the entire structure, wherein the individual coupling rods can certainly have a much lower attenuation decrement. In principle, however, the damping capacity of individual components has a positive influence on the damping decrement of the entire structure. Therefore, it is always desirable to use coupling rods with high attenuation decrements.

Many different considerations have been made to dampen the vibrations of the coupling rods. Of course, it is possible to use according to the proposals of DIN 1055 in cross-section larger sized coupling rods. For example, a coupling rod could be replaced with a 220 mm diameter pipe through a 700 mm diameter pipe. In this case Although the resonant oscillation described above would no longer occur due to the change in the natural frequency of the coupling rod, the material and assembly costs for the installation of the coupling rods would be many times higher. Therefore, a pure oversizing of the coupling rods for economic reasons should not be sought.

Also, individual wind deflectors are conceivable to dampen by shading natural oscillations. These foreclosure experiments have shown that this approach is indeed successful, but for economic as well as procedural reasons, it is also not desirable. Also a vertical bracing by wire ropes is an option to avoid vibrations due to regular vortex shedding. However, vibrations occur not only transversely to the flow direction, but also in the flow direction, so that in addition a horizontal bracing with wire ropes is required. However, in the case of the particularly stressed edge-side coupling bars, an all-round bracing is not possible.

The change in the surface of a coupling rod designed as a pipe, for example, by the installation of additional profiles incorporating a damping mat, is also not suitable to reliably significantly increase the damping decrement of the coupling rod, such as additionally coupled via a steel cable two-mass oscillator. The behavior of a steel cable can not be mapped with sufficient accuracy, so that the behavior of the coupling rod at different wind speeds can not be accurately predicted.

Even tighter clamping at the ends of the coupling rod are not a solution since the vibration loads must ultimately be absorbed by the prestressed screws, which, however, do not have the necessary high fatigue strength due to their bias.

The invention is based on the prior art based on the object, an air-cooled system with arranged on a supporting steel framework Heat exchanger elements exhibit in which the coupling rods have an improved logarithmic damping decrement, without the total weight or the total volume of the coupling rods is significantly increased.

This object is achieved in a condensation plant with the features of claim 1.

Advantageous developments of the inventive concept are the subject of the dependent claims.

Although a variety of different approaches have been practically studied by the Applicant, it has surprisingly been found that the logarithmic attenuation decrement can be improved particularly effectively when a coupling rod is connected to the supports by incorporating an elastomeric, in particular polymeric, damping layer. The elastomeric damping layer is an extremely cost-effective component that can be relatively easily embedded in existing constructions, so that even built steel scaffolds of air-cooled systems can be provided with correspondingly damped coupling rods. The solution according to the invention impresses with its high efficacy, confirmed in test series, with simultaneously low additional costs.

The cross-section of the coupling rods, i. neither the volume nor the mass of the coupling rods need to be changed in the procedure according to the invention over known coupling rods. There are only structural adjustments in the field of connection of the coupling rods to the supports necessary. The damping layers serve not only to increase the structural damping of the entire scaffold, but also to reduce unwanted spikes in the connection area.

Since the condensation plants are installed outdoors, it is necessary that the damping layers of a possible weather-resistant, ozone-resistant and resistant to frost thawing material are made. The lifetime should be over 20 years. The material must be suitable for a non-predominantly static load. Load cycles of> 10 ⁸ to 10 ¹⁰ are to be expected by changing compressions in the material thickness direction as a result of angular distortions in the contact area of the coupling rods. The damping layers should have a mean compressive stress of 4 to 5 Nm / mm ² , as well as a leakage flux of <5% in the material thickness direction. Of course, the damping layers must not embrittle even under harsh environmental conditions and lead to a stiffening. It is essential that the durability of the damping effect during the life of the damping layers is maintained. In any case, it is desirable that the decrease of the damping effect within a period of 25 years is <5%. At present, especially elastomeric ethylene-propylene-diene rubber (PDM) damping layers appear to have the best properties for such long-term use. The specific dimensions, in particular the thickness of the elastomeric Dämpfungsiagen depends on the particular application. The damping layers preferably have a thickness of 3 to 10 mm, in particular of 5 mm.

The damping layers must be kept absolutely safe. Therefore, it is provided that the coupling rods are bolted to the supports, wherein the screws pass through the damping layer. With regard to the concrete connection of the coupling rods, there are a number of variants, the variants mentioned in the claims have been found to be particularly advantageous. Good attenuation decrements have been achieved, in particular, when the coupling rods have end fastening tabs which are screwed to a console arranged on the supports. The damping layers are arranged in this case on both sides of the fastening tab. The consoles can be aligned horizontally or vertically. For horizontal consoles mounting is particularly easy to implement, since the mounting straps on incorporation of a damping layer on the consoles can be placed. Subsequently, the screwing of the fastening tabs can be done with the consoles.

The damping layer on the side facing away from the console is preferably held by a support plate with which the console is screwed. This support plate may additionally be configured in an L-shape, with one leg bolted to the console and its other leg screwed to the support.

The supports of the scaffold are usually I-profiles, which are also referred to as double T-profiles. The I-profiles are characterized by two parallel and connected by a web flanges. The coupling rods can be connected on the flange as well as on the web side with the support. The brackets may therefore be formed by flanges welded to the flanges, and are supported by a rib extending with the bracket and the flange. The rib is at right angles to the welded flat iron, i. to the console. In this way it is prevented that the console in the area of the weld flange flange is permanently subjected to bending. The welded flat bars or consoles with the ribs can be arranged horizontally or vertically. It is also conceivable a mixed connection of the coupling rods, i. the console is horizontally aligned at one end while the console is vertically aligned at the other end of the coupling rod. The attachment tabs at the ends of the coupling rods are adapted to the orientation of the brackets and therefore are preferably at right angles to the support.

But it is also conceivable that the coupling rods have end-side end plates, pointing to the surface normal, in the axial direction of the coupling rod and thus is perpendicular to the support. The parallel to the flange of the support end plates may be screwed under inclusion of a parallel to the end plate arranged damping layer with a flange of the formed as I-profile support. If the coupling rod or the Surface normal is perpendicular to the web of the I-profile, an adapter plate can be welded between the flanges, which is arranged parallel to the end face plate of the coupling rod, so that the face plate is screwed under inclusion of a damping layer with the adapter plate. In the case of tubular coupling rods, this variant has the advantage that the respective pipe end can be closed by the end plate and thus protected against the ingress of moisture. As a result, internal corrosion of the coupling rod is prevented. Even with coupling rods, which are designed as I-profile, this variant is relatively simple and inexpensive to implement.

In coupling rods, which are formed by I-profiles, however, there is also the possibility that their connecting the flanges web is held under inclusion damping layers between opposing brackets. The bridge is virtually clamped between brackets, which can be matched to the length of the bridge, so that the coupling rod is already position-oriented and at the same time vibration-damped by this simple, but effective measure. In addition, however, the flanges of the coupling rod can be arranged under integration of the damping layers between brackets. In this case, each end of the I-profile coupling rod is held by four damping layers, resulting in excellent vibration damping.

To simplify the assembly, it is considered expedient if one of the opposing brackets is welded to the support and the other console is bolted to the support. This not only allows easy installation, but also simplifies the possibly necessary disassembly.

The biasing force with which the damping layers are held has also proved to be an important factor. It is important that the screwing, over which the coupling rods are held on the supports, are sufficiently large. In particular, it must be ensured that the fastening straps are not damaged even under heavy vibration loads lift off the damping layers. Therefore, a sufficient bias of the damping layers and thus the screws is required. The corresponding biasing force can be maintained by incorporating spring elements on a screw head and / or a nut securing the screw. The spring elements are preferably spring washers.

Under certain circumstances, it makes sense to weld the screws with which the connecting rods are bolted to the supports to the nuts. This can ensure that the permanent vibration load does not lead to a loosening of the nuts and thus to a decrease in the damping effect.

With the inventive design of the support structure resonance-like vibrations can be suppressed in a wide range, with surprisingly not only vibrations transverse to the flow direction, but also vibrations in the flow direction could be damped even with horizontally arranged consoles. In this way additional bracing by steel cables and additional, the cross section of the coupling rods changing damping measures are unnecessary. The inventive approach to increase the Däpfungsdekrements is very cost effective and also very effective. Assuming that the attenuation decrement of a freely oscillating coupling rod with a length of 12 m, a diameter of 220 mm with a wall thickness of 6.3 mm at about 0.001 is when the coupling rod is mounted horizontally or at about 0 , 00025, when the end-side bearing is made vertical, attenuation decrements on the order of 0.08 have been achieved in tests with elastomeric damping layers. That's an increase of more than a decade. Such high damping decrements can be achieved with relatively soft EPDM damping layers with a relatively high tightening torque of the screws. However, if the tightening torque becomes too high, the damping decrement decreases again. The optimum range is a tightening torque between 80 and 150 Nm, because the Damping capacity monotonously reduced with increase in tightening torque. Under relatively soft EPDM materials are those having a microhardness, measured according to DIN ISO 48, method M from 30 to 50 IRHD to understand or with a hardness, measured according to DIN 53505, Shore A, at 23 ° C from 30 to 50 Shore ,

The invention will be explained in more detail with reference to the embodiments illustrated in the drawings.

It shows:

Figure 1: A perspective view of a scaffold for a condensation plant;

2 shows a perspective view of the connection region of two coupling rods to a support in a first embodiment;

FIG. 3 shows the connection region of FIG. 1 in an exploded view;

FIG. 3a shows a variant of the embodiment of FIGS. 2 and 3;

Figure 4: a perspective view of the scope of a coupling rod to a support in another embodiment;

Figure 5 is a perspective view of another embodiment of the mounting of a coupling rod to a support;

FIG. 6: an exploded perspective view of the storage arrangement according to FIG. 5;

Figure 7: a perspective view of another variant of a central storage of coupling rods to a support;

8 shows a perspective view of another embodiment of the storage of coupling rods to a support; FIG. 9 is a perspective view of the connection region of coupling rods designed as an I-profile;

Figure 10: a perspective view of another embodiment of a connection of a running as an I-profile coupling rod to a support and

FIG. 11 shows the connection of FIG. 10 in an exploded view.

FIG. 1 shows a scaffold 1 of an air-cooled plant, in this case a condensation plant. The scaffold supports heat exchanger elements not shown in detail, which are positioned in a number of rows roof-shaped above the fan 2. The fans 2 are located at a height of 20 m. The vertically extending supports 3 of the scaffold 1 are connected to each other via horizontally extending coupling rods 4. Overall, a truss-like structure. The individual supports are arranged at a distance of approx. 12 m.

It can be seen that differently configured coupling rods are used, depending on whether diagonal struts are additionally provided in a corresponding compartment or not. In the subjects without diagonal struts are slim, tubular coupling rods 4 are used, as they can be found in particular in the corner region of the support structure of the scaffold 1.

FIGS. 2 to 11 show, in different embodiments, possibilities for connecting the coupling rods 4 to the respective supports. In Figures 2 and 3 it can be seen that the support 3 is configured as an I-profile. It has two opposing flanges 5, which are connected to each other via a central web 6. The coupling rods 4, which are only partially drawn in, have, for example, a diameter of 220 mm with a wall thickness of 6.3 mm. The coupling rods 4 are perpendicular to the support 3. The attachment of the coupling rods 4 takes place in the longitudinal direction of the coupling rods facing fastening tabs 7, partially protrude into the ends introduced slots of the coupling rod 4 and there are welded to the coupling rod 4. However, the attachment tabs 7 also protrude beyond the tubular part of the coupling rods 4 and serve for screw-technical fixation on the support 3. In this embodiment, the fastening tab 7 of the left in the image plane coupling rod 4 has two holes, while the fastening tab 7 of the in the image plane right coupling rod 4 has four holes. In this embodiment, the screw with horizontally arranged brackets 8, which are either welded to the outside of the flange 5 or to the web 6. The welded to the flange 6 console 8 is also laterally welded to the webs 5 of the support 3. At the left in the image plane console 8 a diagonal brace 9 is additionally provided, which is welded below the console 8 on the one hand to the flange 5 and on the other hand with the console 8.

The special feature of the illustrated connection is the use of damping layers 10, which are arranged above and below the fastening tab 7, so that the fastening tab 7 is not directly in contact with the console 8. The respective upper damping layer 10 is also held by a support plate 11. The support plate 11 has the same length and width as the damping layers 10. The bore pattern is the same as in the console 8 and the damping layers 10. The damping layers 10 are held captive between the support plates 11 and the brackets 8, since all components of the shown bolts 12 are penetrated. In this embodiment, the bolts are inserted from below through the holes and secured by nuts 13 and washers 14.

Figure 3a shows a variant in which the brackets 8 are arranged vertically and in which no support plates are used. It is therefore only a damping system 10 is provided. Of course, the same principle can also be applied to horizontal storage as shown in FIG. The embodiment of Figure 4 differs from that of Figures 2 to 3a by differently designed support plates 15. The support plates 15 are configured in this embodiment L-shaped, with her one leg 16, as in the first embodiment, with the console 8 either over 2 screws 12 or about 4 screws 12 is screwed. Her second, upwardly facing leg 17 is bolted to the support 3. The left in the image plane support plate 15 is bolted directly to the flange 5 of the support 3. The right in the image plane support plate 15 is bolted to the web 6 via two screws. This type of connection has the advantage that the outgoing of the coupling rods 4 loads are not transmitted exclusively through the console 8 in the support 3, but in addition on the support plate 15. The welds of the bracket 8 and the rib 9 are thereby relieved. Overall, a higher level of security is created in the connection area.

FIGS. 5 and 6 show a vertically oriented connection. Since they are the same components as in the previously described embodiment, the reference numerals already introduced are retained. Again in this variant, L-shaped support plates 15 are used in combination with brackets 8, which in turn are supported by ribs 9 on the flange 5 and the web 6 of the support 3. Merely to illustrate how the number of screws can be varied, a screw with only two screws is shown in this embodiment in the left in the image plane coupling rod 4, while in the embodiment of Figure 4 is shown a screw with four screws. In principle, it is conceivable that one end of the coupling rod 4 is provided with a connection, as shown in Figure 4, while the other end is provided with a connection, as shown in Figure 5. Ie. a horizontal and vertical connection of the coupling rods can be combined. Of course, a purely horizontal connection is possible as well as a purely vertical connection. The variant of Figure 7 differs from that of Figure 2 in that an adapter plate 16 is welded parallel to the web 5 with the longitudinal edges of the flanges 5. In addition, a spacer is provided, that the adapter plate 16 is supported in a manner not shown relative to the web 6. On the adapter plate 16, the already known from the previous figures console 8 is fixed in a horizontal orientation. The console 8 is in turn supported by a rib 9. In this embodiment, designed as a flat iron support plate 11 is used, as was the case with the embodiment of Figure 2, but with the difference that the support plate 11 is made slightly narrower, so that the holes for the screws 12 in the area the central longitudinal axis of the support plate 11 run. This configuration has the advantage that the screw connection of the coupling rods which run onto the web need not take place in the region between the flanges 5 of the support 3. Overall, the accessibility during installation is much easier.

The embodiment of Figure 8 shows a variant in which the damping layers 10 are not perpendicular to the flange 5 and the web 6 of the support 3, but run parallel to the respective connection surfaces. The tubular coupling rods 4 are, unlike the previous embodiments, not provided with an end protruding fastening tongue 7, but with rectangularly configured face plates 17, either directly to the flange 5 with inclusion of an elastomeric Dämfungslage 10 and with that of Figure 7 known Adapter plate 16 are screwed. The adapter plate 16 is not provided with a console in this embodiment, but itself directly to the connection of the coupling rod 4, of course, incorporating a damping layer 10. An additional damping can be achieved that below the nuts 13 also damping layers 10 are arranged. These damping layers are much smaller and configured only annular. The nut 13 exerts via a support plate 18 a constant biasing force on the annular damping layer 10. The coupling rods can be configured as a hollow profile, ie be circular or in cross-section also square. As coupling rods but are also other profile shapes, such as T or I-profiles, as shown in Figure 9. As in the embodiment of Figure 8, a front plate 17 is provided at the coupling rods 19, which is parallel to a connected to the support 3 adapter plate 16 and bolted via a plurality of screws 12 either with the adapter plate 16 or directly to the flange 5 of the support 3 is. The screwing is again carried out with the inclusion of an elastomeric damping layer 10. Reference is made in this regard to the comments on Figure 8, which also apply in content in the embodiment of Figure 9.

The variant of FIG. 10, on the other hand, does not provide an end face plate in the coupling bars 19 configured as an I-profile, but rather a peripheral fixation of the coupling bar 19. The mounting of the coupling bar 19 takes place in the horizontal direction and in the vertical direction opposite brackets 20, 21, 22, 23. It can be seen in FIG. 11 that in each case one of the horizontally and vertically aligned brackets 20, 22 is welded to the flange 5 or the web 6 of the support 3. The respective consoles are configured L-shaped and provided with two holes through which are screwed during assembly screw. The horizontal bracket 20 forms the support for the lower flange 24 of the coupling rod 19. The coupling rod 19 is placed under inclusion of a damping layer 10 on the lower bracket 20. The upper bracket 21 is configured like the lower bracket 20 L-shaped, wherein each leg of the upper bracket 21 is screwed with the inclusion of an elastomeric damping layer 10 on the one hand with the flange 5 of the support 3 and the other with the upper flange 25 of the coupling rod 19th

In addition, a fixation of the flanges 24, 25 of the coupling rod 19 connecting web 26 via the vertically oriented brackets 20, 23. The console 23 is, as well as the console 22, L-shaped configuration and on the one hand with the flange 5 of the support. 3 and on the other hand with the web 26 screwed the coupling rod 19. In this case, damping layers 10 are arranged on both sides of the web 26, as well as between the flange 5 of the support 3 and the screwed console 23. The connection of the right in the image plane coupling rod 19 is carried out in the same manner described above, but with the difference that the corresponding brackets are not bolted to the flanges 5 of the support 3, but with the web 6. Therefore, reference is made to the preceding embodiments for connection to the flange 5 reference.

Reference numerals:

1 - Scaffold

2 fans

3-post

4- coupling rod

5- flange

6- bridge

7 - fastening tab

8 - console

9 - rib

10- damping system 11 - support plate

12- screw

13- mother

14 - Washer

15- support plate

16 adapter plate

17- forehead plate

18- support disk

19- coupling rod

20- Console 21 - Console

22- console

23- Console 24 - Flange 25- Flange 25- Bridge

Claims

claims

1. Air-cooled system with on a supporting support frame (1) arranged heat exchanger elements, wherein the support frame (1) a plurality of vertical supports (3) and adjacent supports (3) interconnecting coupling rods (4, 19), characterized in that at least one coupling rod (4) with the inclusion of an elastomeric damping layer (10) is connected to the support (3).

2. Air-cooled installation according to claim 1, characterized in that the coupling rods (4, 19) are screwed to the supports (3), wherein the screws (12) pass through the damping layer (10).

3. Air-cooled installation according to claim 1 or 2, characterized in that the coupling rods (4) end fastening lugs (7), which are screwed to one of the supports (3) arranged console (8), wherein damping layers (10) on both Side of the fastening tab (7) are arranged.

4. Air-cooled system according to claim 2, characterized in that the damping layer (10) on the bracket (8) facing away from the fastening tab (7) by a support plate (11) is held, which is bolted to the bracket (8).

5. Air-cooled plant according to claim 4, characterized in that the support plate (15) is configured L-shaped, with her one leg (16) with the bracket (8) and its other leg (17) screwed to the support (3) is.

6. Air-cooled installation according to one of claims 2 to 4, characterized in that the supports (3) are formed by I-profiles, the two mutually parallel and via a web (6) interconnected flanges (5), wherein the Consoles (8) from to the Flanges (5) welded flat iron are formed, which are supported via a with the bracket (8) and the flange (5) extending rib (9).

7. Air-cooled installation according to one of claims 3 to 6, characterized in that the brackets (8) and fastening tabs (7) at one end of a coupling rod (4) horizontally and at the other end of the coupling rod (4) are arranged vertically.

8. Air-cooled installation according to one of claims 3 to 5, characterized in that the fastening tabs (7) are at right angles to the support (3).

9. Air-cooled installation according to claim 1 or 2, characterized in that the coupling rods (4, 19) have end-side end plates (17) whose surface normal in the axial direction of the coupling rod (4, 19) and is perpendicular to the support, wherein the end plates ( 17) with the inclusion of a parallel to the end plate (17) arranged damping layer (10) with a flange (5) formed as an I-profile support (3) are screwed or with a parallel to the flanges (5) interconnecting web ( 6) of the support (3) extending adapter plate (16) are screwed.

10. Air-cooled installation according to claim 1 or 2, characterized in that the coupling rods (19) are formed by I-profiles, the mutually parallel flanges (24, 25) connecting web (26) under inclusion damping layers (10) between Consoles (22, 23) is held.

11. Air-cooled installation according to claim 10, characterized in that the flanges (24, 25) of the coupling rod (19) under inclusion of damping layers (10) between brackets (20, 21) are arranged.

12. Air-cooled system according to claim 10 or 11, characterized in that in each case one of the opposite Consoles (20,22) is welded to the support (3) and the other console (21, 22) with the support (3) is screwed.

13. Air-cooled installation according to one of claims 1 to 12, characterized in that the elastomeric damping layer consists of ethylene-propylene-diene rubber.

14. Air-cooled installation according to one of claims 1 to 13, characterized in that via the screws (12) for fixing the coupling rods (4, 19) on the supports (3) one which the damping layers (10) biasing screwing force is applied, the are arranged under inclusion of spring elements between a screw head and / or a screw (12) securing nut (13).

15. An air-cooled plant according to claim 14, characterized in that the biasing screwing force is chosen so large that the contact between the damping layers (10) and the adjacent components is maintained under the expected vibration load.

16. Air-cooled installation according to one of claims 1 to 15, characterized in that screws (12), via which the coupling rods (4, 19) are screwed to the supports (3), with the screws (12) securing nuts (13 ) are welded.