DE2240349A1 - SUPPORT CONSTRUCTION FOR HEAT EXCHANGER PIPES - Google Patents

Description

August 10, 1972 Anw, ^ File: 27.28

PATBIT AIM

The Eaboook & fileox Company _? -jgi says 42nd Street,

New York, NY , 1OQT7 -USA

Support structure for heat exchanger pipes.

The invention relates to a support structure for heat exchanger tubes and in particular on tube sheets as well as a method for the production of itohrplatten, which the heat exchanger tubes support in the riser chamber between opposite tube sheet surfaces.

Large machines are almost an essential feature of contemporary industrial activity. Heat exchangers in many chemical process plants, power generation plants and marine propulsion systems, for example, are typical of this trend towards large-scale designs, which are almost inevitable result from the fact that large quantities of media must be enforced.

For example, in a pressurized water nuclear power plant, the

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Steam generator that removes the heat generated in the reactor from the Primary coolant transferred to the secondary coolant driving the turbine turbines, a length of up to 25m and an outside diameter of about 4m «, Within one of these heat exchangers, the tubes through which the primary coolant flows can each have an outer diameter of not more than 16mm but an effective length of 16m between the fixings of the Tube ends in opposite faces of the tube sheets, typically a bundle in one of these Heat exchangers include more than 15,000 tubes. It is clear that there is a need to tive support for these'pipes in the span create between tube sheet surfaces to provide tube spacing, adequate rigidity, and the like.

In the past, grids have been used to form these support, which are used on a regular basis Distances were arranged in the tube bundle between the tube sheets. These grids usually include open cells formed from interlocking strips of metal. Those that make up the cells Strips capture the sides of the tubes, which are arranged in the relevant grit tern. These lattice structures are unsatisfactory because they lack firmness and because they become one Number of manufacturing difficulties.

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Another way to solve the pipe support problem has been to develop a drilled plate structure guided. This support system consists of a series of flat plates that fit into the heat exchanger be arranged so that their planes ^ transverse to the longitudinal axes of the tubes in the bundle, holes are drilled in each of the plates to To include pipes. The secondary coolant flow connection is through these plates created by adding additional holes in those Panel sections are drilled in the middle of each of the three tubes Bundle. Though these drilled panels are stronger than the grid construction, the tube mounting holes each have to be slightly larger Have diameters greater than the outside diameter of the associated tubes in the bundle. This size difference is necessary because the individual tubes are usually not perfectly straight and because the holes in the plates are not exactly aligned. So a certain tolerance is necessary to accommodate these manufacturing differences in the heat exchanger assembly. Based on these The center lines of the ■ individual pipes are not slightly different from the centers of the respective pipes Holes in alignment. This leads to the individual Pipes rest against one side of a hole and leave a thin crescent-shaped gap between that

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Pipe and the rest of the area of the hole in question permit.

The points where the crescent-shaped edges end, however, tend to promote an undesirable condition known as "crevice corrosion". The term "crevice corrosion" is generally used to refer to a number of physical and mechanical effects applied, many of which are not properly defined »In any case, crevice corrosion leads to a Impairment of the pipe and plate construction.

For the sake of explanation it should be pointed out that it is believed that there is some kind of crevice corrosion in the crevices the crescent-shaped ends by the evaporation of successive droplets of secondary coolant is due. These droplets form on the metal surfaces in the narrow end spaces. The heat transfer process causes the evaporation of the droplets, leaving in many cases a small residue of solids remains. The process repeats itself several times and creates an accumulation of solids that eventually pitting or corrosion of metal surfaces. Damage these - ^ rt cause costly and time-consuming repairs or, if they are not under control, a pipe rupture.

Another type of heat exchanger tube support plate is

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has been proposed and comes with "clover leaf" construction designated. The shamrock plates are drilled; each hole has inward and on Spaced fingers that touch the surface of the associated pipes. Though direct contact between the tube and the plate eliminates the gap and thus the source of the crevice corrosion that is drilled Plate construction, the cloverleaf construction is nevertheless the one above for large heat exchangers The general dimensions described are unsuitable because there is no play to the cumulative effect of the lack of pipe straightness and the. to take into account minor flow errors in the bores " The invention is therefore based on the object to provide a strong heat exchanger tube support plate that does not promote corrosive attack. The plate should ^ te in addition, no obstacle to efficient assembly of the heat exchanger. . ■ ■ -. '

The object is achieved according to the invention in that at least three projections are arranged in each bore and the innermost end of the projections ends on an arc that describes a circle, which is a Has diameter that is slightly larger than that Outside diameter of a single pipe * the inside the respective hole is to be recorded. This is supposed to bulges for a certain flow cross-section are formed between adjacent pipes, if that

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respective tube is inserted. The projections hold the outer surface of the respective tube, but without that they all grasp or touch this outer surface. Bays that protrude inward between these Spaces are formed in the individual support plate openings when the associated pipe is inserted is to flow channels through the plates form. The inwardly protruding points end in arcs that describe a circle with a diameter which is only slightly larger than the outer diameter of the associated pipe. For example, it has been established that a game from 0.125 to. Cp75mm between the Outer surface of the tube and the inner end of an adjacent one Place gives a satisfactory assembly tolerance and excludes crevice corrosion.

.After the heat exchanger is assembled, a Pipe generally inen rest on two of the inwardly protruding points in a line contact, which in the essentially leaves no gap. The gap between the third inward protruding point and the adjacent one Section of the outer surface of the associated ttohrs is too wide to have crevice corrosion effects to promote. Thus, a support plate is created according to the invention, which the structural strength and maximizes the flow area in such a way that that a reasonable clearance for the heat exchanger assembly is given without crevice corrosion

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develop.

By, changing the depths of the. Individual bulges can also be adjusted, adjusted, or otherwise, the flow through the support plate manipulate to the specific "fan mix and hydrodynamic Requirements within the heat exchanger Enough to do »

From a slightly different point of view is invention continues to use a manufacturing process for heat exchanger tube support plates directed. By way of illustration, it should be said that the problem of the precise training of more than 15,000 non-circular holes in a plate with a diameter of about 12 feet thereby solved is that you first drill the appropriate number of holes whose diameter is slightly larger than are the outside diameter of the pipes in question. Preference « wisely the edges of these holes are beveled. At least three holes or bays are then passed through one Broaching process formed from each of the chamfered holes. The depth of the broaching process determines the flow cross-section, the maximum depth of broaching being limited only by having enough metal between each opening must be left in order to ensure adequate strength and stability of the panel and pipe construction to ensure.

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Ala an optional manufacturing process can be sufficient Holes are drilled in the plate to accommodate the tubes in the bundle, being the diameter of the drilled Holes is slightly larger than the outer diameter of the pipes in question. A multi-spindle drill is preferred used to drill three lobes in the perimeter of each of the initial holes. The resulting non-circular openings are finished with a reaming tool to create a to result in a smooth, burr-free surface.

Of course there are openings with more than three bays and three inward protrusions within the invention and may vary depending on the circumstances used to the extent required. the In addition, the support plate itself does not need to extend over the entire cross-sectional area of the tube bundle, but can, if necessary, only support part of the tube bundle in any plane.

The various features that characterize the invention emerge particularly from the claims » To better understand the invention, its operational advantages and how it was used For specific purposes, reference is made to the accompanying drawing and description, in which a preferred Embodiment of the invention shown and figured is described. Show it:

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ge 1 is a complete vertical section through one Burchlaufdaa & pferzeuger and ·

, 2 is a plan view of a part of a support plate and tube construction according to FIGS. 1 and

3 shows a plan view of part of a support plate, with the heat exchanger tubes removed and

Fig «, 4 a system for fastening the support plates inside the heat from oher Konstrukt ion and

Jiga 5 is a plan view of part of a support plate according to another embodiment of the invention

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For a better understanding, typical features of the invention in connection with a steam generator are presented described for a nuclear power plant »although this Principles in general for dumbbell and tube heat exchangers in any number of different fields of activity are applicable. As shown in FIG. 1, the steam generator 10 consists of a vertically arranged one cylindrical pressure jacket 11, the ends of which are closed by an upper collector 12 and a lower collector 13.

The upper collector 12 consists of an upper tube sheet U, a primary coolant inlet 15, a manhole 16 and a handhole 17 "The manhole 16 and the handhole 17 are used for inspection and repair in the times in which the" steam generator system 10 is out of operation " The lower collector 13 includes the drainage 18, a coolant outlet 2O _9, a hand hole 21, a manhole 22 and a lower tube sheet 23 *

The steam generator 10 is supported on a base 24, which encloses the outer surface of the lower floor 13 and supports the steam generator 10 above the floor 25

As mentioned earlier, the total height is one typical heat exchanger of the present type about 25 m between the bottom 25 and the upper extreme end of the Coolant inlet 15 · The total diameter is

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about 4- m. To have a certain quantitative idea of to convey the capacity of such a heat exchanger, it should be pointed out that it has 30,000 tons of primary coolant per hour "prevailed in the output operating conditions.

Within the pressure jacket 11 encloses a lower cylindrical tubular jacket 26 - also a shell or a steering wall called - a bundle of heat exchanger tubes 27, a part of which is illustrated in Figure 1. In a heat exchanger of the present type is the number of tubes enclosed within the steering wall 26 more than 15,000, each of the tubes having an outside diameter of 16 mm. It has been found that inoonel is a preferred tubing material for use in Steam generators of the type described is. The single ones Pipes in bundle 27 are anchored in respective holes in the upper and lower tube sheets 14 and 23 are arranged} the anchoring takes place by expanding the tube ends within the tube sheet.

The lower steering wall or shell 26 is within the Pressure jacket 11 aligned by pins not shown. Fasten screws, also not shown the lower steering wall 26 on the lower tube sheet 23. The lower edge of the steering wall 26 has a Group of rectangular water nozzles 30 on, through

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the feed water enters the riser chamber · The upper one The end of the steering wall 26 also provides a flow connection between the riser chamber within the steering wall 26 and an annular fall space 31, which between the outer surface of the lower steering wall 26 and the inner surface of the cylindrical pressure jacket 11 is formed The flow connection takes place via a gap 52.

A hollow, annular, secondary coolant feed water inlet header 34 surrounds the outer surface of the pressure jacket 11. The collector 34 is in flow connection with the annular fall space 31 over a series of radially arranged feed water inlet nozzles35 and As shown by the direction of the arrows contained in Figure 1, feed water flows from the collector 34 into the Steam generator unit 10 via the connection 35 and 36 · The Feed water is fed from the nozzle into the annular fall chamber 31 and flows through it downwards and then enters the riser chamber through the water nozzle 30. The secondary coolant feed water flows within the riser chamber upward within the baffle 26 in a direction that of the downward flow of the primary coolant inside the tubes 27 is opposite · An annular plate 37, which between the inner » surface of the pressure jacket 11 and the outer surface of the lower edge of an upper cylindrical steering wall or shell 33 is welded, ensures that the feed water entering the fall chamber 31 down to the

«» 13 ··

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Water connection 30 in the indicated by the arrows Riohtung flows * The secondary medium absorbs heat from the primary medium through the tubes in the bundle 27 and rises to the top to evaporate inside the chamber, which is formed by the guide walls 26 and 33 »

The upper steering wall 33 », which is also with the pressure jacket 11 aligned by alignment pins not shown is attached in a corresponding position because it is directly "below the steam outlet nozzle 40 is welded to the pressure jacket 11 by the plate 37 «The upper guide wall 33 continues to surround approximately one Third of the tube bundle 27.

A üilfsspeisewasserammersammler 41 is in flow connection with the upper part of the pipe bundle 27 via a. or several nozzles 42 ₉ which penetrate the Druok jacket 11 and the upper guide wall 33. For example, "This auxiliary s feedwater = * system is used to the steam generator 10 in the unlikely Pail filling _s that an interruption of the supply water flow from the accumulator 34 üie eintritto previously mentioned" transforms the by whether © a duroh the tube bundle 27 in by the arrow © darg © · "presented Riohtung flowing feed water or S '@ kia & dä? <=> coolant into steam" in the off "depicted is ^ management form this? Daapf üoito ^ down overheated _s fe ©« = before it the Upper edge of the upper Is @ n! Cwma5 33 eraalolü; ₀ ■ This superheated steam flows into & ®% tefofe dea arrow

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indicated direction over the upper edge of the steering wall 33 and down through an annular outlet channel 43 »the one between the outer surface of the upper cylindrical steering wall 33 and the inner surface of the pressure. * - · jacket 11 is formed.

In the channel 43, the steam leaves the steam generator unit 10 through steam outlet nozzle 40, which with the channel 43 are in communication. In the aforementioned way, the secondary coolant is of the feed water inlet temperature raised to a superheated steam temperature at the outlet connection 40. The ring plate 37 prevents the steam from - getting in contact with the incoming To mix feed water in the fall space 31. The primary coolant flows a-n das releasing this heat Secondary coolant from a nuclear reactor, not shown, to the primary coolant inlet 15 in the upper header 12, flows through individual tubes in the heat exchanger tube bundle 27 to the lower header I3 and is exhausted through coolant outlet 20 to flow back to the nuclear reactor which removes the heat generated, from which useful work is ultimately derived.

For the general size of the present heat exchanger, there are more than 15,000 bridging tubes in the bundle 27 a distance of 16 m between the upper and lower tube sheets 14 and 23. To put these tubes in their respective

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Holding layers is a series of substantially flat support plates: 44 across the longitudinal axis of the tubes arranged in the bundle 27 and the axis of the pressure jacket 11.

As shown in FIG. 2, the support plate 44 has openings 46, 47, 48 and 49. Each of these openings receives a corresponding heat exchanger tube 5-0, 51, 52 and 53 * ^{1. For} a heat exchanger of the present size, it has been found that a 38 mm thick plate made of carbon steel provides adequate tube support. Inconel 50 Ms 53 tubes generally provide matching tube and plate thermal expansion coefficients. This avoids the development of structural stresses otherwise caused by differences in this coefficient. As shown in connection with the opening 46, each of the openings 46 to 49 has at least three inwardly projecting protrusions. For example, the opening 46 has protrusions 54, 55 and 56. The innermost portions of the protrusions 54, 55 and 56 terminate in arches that describe individual arcs. The circle described by these three arcs has a diameter which is slightly larger than the outer diameter of the tube 50 arranged within the opening 46.

If the longitudinal axis of the tube 50 is not straight Line deviates and the axis of the pipe coincides with the axis of the

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The circle coincides with the arcuate ends the protrusions 54, 55 and 56 is formed, then, as has been found, there is a little play in the On the order of about 0.025 mm between the opposing surfaces of the tube and the arcuate protrusions suitable for the purposes of the invention.

In practice, however, manufacturing tolerances are used the position of the openings as well as deviations of the longitudinal axis of the individual pipes from the straightness in almost every one Case cause the tubes to abut one or more of the innermost ends of the projections, as shown in FIG Connection to pipe $ 0 in opening 46 is shown. Thus, the tube 50 lies at the arcuate ends of the Projections 55 and 56 on. This leaves a misalignment a gap between the outer surface of the tube 50 and the arcuate end of the protrusion 54 · It is a Another feature of the invention that the gap is sufficient is wide in order to avoid the onset of crevice corrosion.

In Figure 3 exemplary openings 63 »64 and 65 in a part of a support plate 66 is shown. These openings are each through different flow cross-sections marked so that the distribution of the secondary tributary can be selectively adjusted or adjusted via the plane of the plate 66, e.g. special fluidic and thermodynamic

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To meet the requirements of a heat exchanger In order to accommodate, for example, a tube (not shown in FIG. 3) with an outside diameter of 15.9 mm, a maximum flow cross-section through the opening 63 is offered. Typically, the innermost arcuate ends of the projections 67, 70 and 71 describe a circle having a diameter of 16.7 mm. The arc of the "circle formed by each of the ends of the projections 67, 70 and 71 is typically 22 ° _o. This arcuate narrow surface creates an almost gap-free condition when in contact with the outer diameter of a pipe. This unique bay formation also results an optimally em balance between the secondary coolant pressure "loss when flowing through the support plate and the structural strength of the individual plates" Accordingly, the apertures 64, 65 having the smaller flow cross-sections, the same inwardly directed ¥ orsprünge, preventing by this gap corrosion state maintain.

A change in the flow cross section available through the plate 66 therethrough is effected by _s that "in the formation of the openings, the depth of the bays 72 ₉ 73 and 74 selects" These bays are z "Bo limited by arcs of a circle, the maximum the © Buohttiefe results _o iieser bay circuit is also formed concentrically with dsm circuit ₅ by the innermost ends d © © r projection 6I ₀ 70 and 71 irjireL So hmt ^ ₀ BI feel of di © opening S3

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Characteristic figuratively, α shown Ausafünrungaform the invention, this circle has a diameter of 21.8 mm · An arc of preferably 58 ° is formed by the maximum depth of each of these bays. Inclined linear transitions 75 and 76 connect the ends of the arcuate portions of inwardly protruding projections 14 and 70 with the. Ends of the arch surface which defines the deepest point of the bay 72.As shown in FIG. 3, these transitions 75 and 76 form angles of about 20 ° a heat exchanger tube is arranged within the projections.As already mentioned, this reduced flow cross-section is determined by reducing the radius of the circle which is described by the arcs which characterize the maximum depth of the bays.

In the same way, when a tube is used (not shown in Pig. 3), the flow cross section is Opening 65 in Fig. 3 is only one third of the flow area in opening 63 · A typical bay size for opening 65 should be when used in conjunction with a Pipe, which has an outside diameter of 15 »9 mm, describe a circle that has a Durohmesser of 18.3 mm having. The sloping transitions, the inward ones Separate protruding points from the adjoining bays, of course, all have the same length and are the shortest 'in the three openings shown in Fig. 3 »

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These slopes each form the same angle. The curved ends of the bays also form an angle τοη 81 ° 20 ^l .

In this context it should be noted that a circle described by bay ends which Have a diameter of 20 mm, the desired reduction in the flow cross section for the opening 64 results «, The inclined transitions for the opening 64 are shorter than the corresponding transitions for the larger opening 63, to take into account the shallower bay depth «,

If we turn again to Figure 1, then see we that the pipe does zplatteEE 44 inside the Dampferfceugeraggregata 10 are fixed in their position by a support rod system 77 · Larger details of this Sragstangensystems emerge from Fig.4, which is a part of the lower tube sheet 25 shows, The tube sheet 23 is with a hole 80 is formed which receives the end of a support rod 81 made of steel. The end of the pole 83 is fixed in the tube sheet by widening it or by some other suitable means. One made of steel hollow spacer tube 82, the inner diameter of which is much larger than the outer diameter of the carrying diameter rod, encloses the inner part of the rod 81 and runs above the inner surface of the tube sheet 23 “Die The length of the spacer tube is the same as the torher specified Spaced between the inner surface of the tube sheet 23 and the opposite face of the pipe support plate 44.

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Plate 44 has a hole with a diameter which is large enough to accommodate the external durometer of the Support rod 61 on üunehateh «This diameter is However smaller than the outer diameter due to Abr etandsrohra 62. In this way, the In-. nenflache of the tube sheet 23 opposite Surface of the support plate 44 on the upper transverse end of the spacer tube Θ2 detected and held. X In the same way the next one is vertically down The supporting plate (not shown in FIG. 4) stood sound of the upper surface of the plate 44 through a spacer tube 64 is separated for each continued on the following plate until the whole row within the riser chamber is made.

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About pipe vibrations. To avoid at resonance frequency, it is advantageous to produce a non-uniform distance between the individual flat traveling · So z _e are preferably incorporated as in the effective pipe length of 15 »m 85 support plates at intervals of about 0.91 m. However, these distances are in each case a few centimeters more or less than 0.91 m. For explanation, it should be said that there is a distance of 1.17 m between the inner surface of the lower tube sheet 23 and the support plate next in the sequence. The distance between the plate 44 and the next plate above the plate 44 just mentioned is 0.97 m and so on through the remainder of the tube bundle 27 through it. The plate spacing should avoid a construction in which two successive support plates have the same distance from one another as there is between the plates immediately above and below the two plates of which we are talking here.

If we turn to the]? Ig.1 au again, we see that the! rod system 77 is attached to the uppermost support plate 85 i3t »support rod screw ends (not shown) are duroh also not shown nuts detected, which are tightened so that they are on the Surface of the plate 85 abut and the support rods to tension bias while they apply a compressive force on the Exercise circumferential spacer tubes.

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Another important feature of the invention is included the manufacturing techniques that have been developed to produce the support plates described herein. It should be remembered that a support plate in a heat exchanger of the type under consideration has more than 15,000 Pipes picks up when it engages all of the pipes in the bundle. Sa bie to 15 support plates in one of these heat exchangers can be present and very often up to 4 heat exchangers in a power reactor system, it is clear that even minor savings in support plate manufacturing to substantial reductions! the Gr6samt-Wännetau3cheB costs can lead

For example, the openings shown in FIG. 3 are produced by first drilling holes in the plate 66 in a group in which the number of holes is the same as the number of pipes to be supported. arcs Wirde described which 63 (Figure 3) characterize the innermost part of the protrusions 67 _f 70 and 71 in the mouth, although this radius may be produced by a machining operation End ··. The bays 72, 73 and 74 are then created by a broaching process which removes the unwanted metal to a certain depth.

flg.5 shows an opening 86, which is in part of a Plate 87 by something other than that in connection with

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Fig. 5 is manufactured. Although the Opening 86 does not offer as much flow cross section as the corresponding produced by a Räumvorgarig opening 63 »however, the manufacturing technology is less so costly than in the case of the drilling and broaching procedures. . ·,. ·: .. "- ■ ■ ■ -, -

A first hole is made around the opening 06 the plate 87 gebGnrty Biesesherste hole can eiiien Have a diameter »which is slightly larger than that Outer diameter of the tube, which is accommodated in the finished opening 86, although this diameter can be produced by a finishing process. For example, a pipe with an outside diameter knife of 15.9 mm require a hole with a diameter between 16.3 mm. and 16.5 mm * The opening bays are then made using an annual spindle drill that drills the bays in the perimeter of the first hole formed · For a maximum Flow cross section in a plate made of carbon steel, is 38 mm thick and has openings to accommodate 0.625 mm pipes, should the bay holes each have a diameter between 12.5 mm and 12.7 mm. The maximum depth this bays also touches a circle which has a diameter between 23 mm and 22.5 mm where the center of this tangent circle lies at the same point as the center of the first drilled

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Hole with a diameter of 16.3 now «After that middle hole and the associated bay are formed, the opening 86 is opened by a reaming tool finished

The heat exchanger shown in Pig.1 is assembled by using the invention the characterizing tube support plates, that clamps the plates in a device "The openings in each of these plates are exactly i aligned with the corresponding apertures in the next plates. Pipes are then inserted through these aligned openings, the clearance provided in accordance with the invention allowing sufficient tolerance to accommodate minor misalignment in the openings and tubes. "

Tube sheets, support system, floors, steering walls, pressure jacket and other parts of the heat exchanger are added to the structure to give a finished product. When the heat exchanger is completed and installed, then the tubes are in the respective Plates brought into line contact with one or more, but not with all, points that in each corresponding opening protrude.

Thus, the present invention provides an effective technique for eliminating many shortcomings

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to manufacture an improved backing plate according to the prior art.

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Claims (1)

Claims lly support structure for heat exchanger tubes, consisting of from a tube plate with bores, characterized in that in each bore (46, 47, 48, 49) at least three projections (54, 55, 56 or 67, 70, 71) are arranged and the innermost The end of the projections ends on an arc that describes a circle which has a diagonal knife, which is slightly larger than the outer diameter of a single pipe that is inside the respective Boring is to be taken with the stipulation between adjacent pairs of pipes bays (72,73,74) for one to form a certain flow cross-section when the respective pipe is inserted. 2 «support structure according to claim 1, characterized in that g e mark Verify that the projections have sides that have the deepest points of those mentioned between Define adjacent pairs of bays, with the lowest points of the bays each describe a circle that has a larger diameter than the circle that goes through the said innermost ends of the protrusions will be described. 3. Support structure according to claim 2, characterized in that the lowest points of the - 26 - 309811/0697 Booked a circle "touch that has a center, which coincides with the center of the said circle, that through the innermost ends of the projections is described, 4 heat exchanger, which is a generally flat plate having a number of openings formed therein and a plurality of tubes, at least some of which are each disposed in one of the openings are characterized in that at least three projections arranged in each of the openings protrude inwardly to the respective arranged tube and the innermost ends of each of the projections end in arcs that describe a circle, the diameter of which is slightly larger than the Outer diameter of the respective pipe; less than all of the projections engage the tube in question in line contact, while a gap between the Outer surface of said tube and less than all of the protrusions formed is crevice corrosion between the respective pipe and the named points. 5 · Heat exchanger according to claim 4, characterized in that all of the tubes in the plurality are each arranged in an opening in the plate. 6. A heat exchanger comprising: a pressure jacket having a 30 9811/0697 " ^2? " Longitudinal axis, an upper tube sheet transversely to the mantle tube, a lower tube sheet transverse to the shell axis, a plurality of heat exchanger tubes within the Pressure jacket between the tube sheets, a number of plates transverse to said jacket axis, each Pair of plates is spaced apart from one another at a different distance than adjacent pairs of plates and from the tube sheets where the named tube sheets are each adjacent to one of the named plates) the plates have openings formed therein to receive at least some of the heat exchanger tubes) each of the tube receiving openings has at least three projections to hold the tube in question, wherein the innermost ends of the protrusions end in arcs that describe a circle whose diameter is slightly larger than the outer diameter of the respective Tube which engages at least one of the projections in line contact, characterized in that that a gap between at least one other of the projections and an adjacent outer portion of the pipe is formed in order to avoid crevice corrosion in the heat exchanger. 7 · Heat exchanger according to claim 6, characterized in that a support rod on one of the Tube sheet is attached and a number of spacer tubes concentric to the rod and between the ge - 28 - 309811/0697 called plates are arranged, each of the plates having a hole formed therein for receiving the Rod and the spacer tube have outer diameter, which are at least larger than the diameter of the support rod hole to which the spacer tube is assigned is. 8. A method for producing a heat exchanger tube support plate, characterized in that first a hole is drilled in the plate and then the formation of at least three bays in the circumference of said hole takes place, the depths of the bays by the required heat exchanger flow cross section and the structural strength of the support plate can be determined and the lowest point of each of the bays describes a circle whose diameter is significantly larger than the outer diameter of the heat exchanger pipe _{0 to be arranged therein} 9. The method according to claim 8, characterized in that that the hole is beveled. 10, method according to claim 8, characterized in that the formation of said bays includes the process by which the material is cleared from 4 @ Ö named bays. - 29 309811/0697 11. The method according to claim 8, characterized in that the formation of said Bays includes the process by which the material is drilled out of the bays. 30981 1/0697 Blank page