DE2430161C2 - Heat exchangers with a circular or hexagonal cross-section - Google Patents

Description

30th

The present invention relates to a heat exchanger of circular or hexagonal cross-section with a number of within an outer Leitmantels arranged and combined to .Rohrbündeln straight tubes, each tube bundle of is surrounded by a conductive jacket open on both sides and together with this conductive jacket and the one on his Both ends of the associated tube sheet with collector hoods forms a structural unit and wherein the Unit arranged in plan in a hexagonal grid and adjacent tube sheets on the entry and exit side of the tube bundle against each other in the horizontal direction are offset.

Such heat exchangers, which essentially according to - * s DE-OS 14 01 666 or FR-PS 8 96 877 are known, are preferred in closed gas turbine systems and used in nuclear power plant technology, where they are used, for example, in so-called integrated Nuclear reactor in the same pressure vessel as the reactor core.

State of the art is also a heat exchanger described in DE-OS 21 20 544, consisting of individual elements arranged in parallel, in which the individual elements or tube bundles have a round or polygonal cross section and are surrounded by casing tubes open on both sides. The external medium, e.g. B. the exhaust gas coming from a turbine is guided along the exchange pipes within the casing pipes, which are open on both sides, with its flow direction being opposite to that of the medium located in the pipes. Each tube bundle is provided with its own inlet and outlet lines through a pair of tube sheets. Tube bundles, tube sheets and casing tube each form a structural unit. <*

From DE-OS 14 01 666 a heat exchanger is also known which has a number of in a jacket Contains tube bundles, the tubes of which are connected at their ends with headers or tube sheets. the Tube bundles each form a structural unit with the head pieces. The essentially straight tubes are in Immediate vicinity of the head pieces so spread apart that they over most of their length a assume uniform distribution over the cross-section of the jacket. The tubes of each bundle will be held in the desired position by spacer plates. To when closely spaced Spacer plates to create the necessary space for the circulation of the heat exchanger medium through the jacket, the structural units are staggered vertically, with half of the headers at one end of the The diameter of the heat exchanger lies in one level and the other half in a slightly lower level dt r head pieces is approximately equal to the diameter of the expanded tube bundle. Is disadvantageous in this heat exchanger that in the end regions of the heat-transferring surfaces, namely between the head pieces and the spacer plates, the bundle tubes are no longer evenly distributed

In FR-PS 8 96 877 another heat exchanger with straight tubes combined to form tube bundles is used described, each used at the bundle ends in a tube sheet with a subsequent collector are. The tube bundles are arranged approximately on three pitch circles, with the tube bundles of the middle pitch circle with respect to the tube bundles of the other two pitch circles offset vertically downwards are. The offset, which is more than the entire length of a collector, enables it to be denser Arrangement of the tube bundle without hindering the medium flowing around the bundle tubes entry

GB-PS 5 75 814 also discloses a shell-and-tube heat exchanger known with staggered arrangement of the tube bundles Here, too, the tube bundles are in the Height offset from one another in such a way that the collector is on two different horizontal levels are located.

It is also known that the individual tubes of a heat exchanger tube bundle in outline in one To arrange hexagonal grids, as shown in US-PS 33 96 784.

Starting from one of the heat exchangers just described with two different horizontal ones The invention relates to structural units arranged on levels and consisting of tube bundles with their tube sheets The object of the invention is to design a heat exchanger of the type described above so that an available limited space is optimally used for heat transfer and the Efficiency is increased.

The object is achieved according to the invention in that the displacement of the tube sheet in three different horizontal planes is made, in such a way that each of the tube sheets three Adjacent building units forming an equilateral triangle in plan on the various levels are arranged, and that the distance between the central axes of the guide jackets is equal to or approximately equal to the sum is the radii of a guide jacket and a tube sheet.

By relocating the tube sheets in three levels in the specified manner, the guide jackets can be Bring structural units into the closest arrangement possible without the outside access to the Bundled tubes of flowing medium to the spaces enclosed by the guide jackets is hindered.

This closest arrangement is present if according to the invention of the distance between the central axes of the Leitmäntel is equal to the sum of the radii of a guide jacket and a tube sheet, if the So overlap the tube sheet, s

The heat exchanger according to the invention can be used with particular advantage as a recuperator in a closed Gas turbine cycle or in the primary cycle of a gas-cooled high-temperature nuclear reactor Helium turbine are used because it has good ι ο heat transfer properties as a result of the good Space utilization has a low construction volume

The inner guide jackets surrounding the tube bundle can be round or hexagonal Have cross-section. With the latter there is an even more favorable use of space than with guide jackets with a round cross-section The tube sheets into which the tubes of each tube bundle are inserted expediently a cross-sectional shape adapted to the guide shells, i.e. they are either round or hexagonal.

The heat exchanger can be operated on the cocurrent or countercurrent principle. The size there- presses, Pressure differences, temperatures and temperature differences of the inner medium flowing through the pipes and of the medium flowing around the pipes into the inner Conductive jackets of the flowing external medium can be of any desired type. As a profit-exchanging media Both gaseous and liquid media come into consideration, whereby it is optional whether the high-pressure or the low-pressure medium is passed through the pipes.

The possible number of structural units arranged in the hexagonal grid results from the mathematical one Formula:

n = 6 (l

if / is used to denote the number of hexagons in the grid.

The staggered arrangement of the tube sheets is on both sides of the tube bundle (at the inlet and Exit side). If the tube bundles are all to have the same length, the tube sheets are arranged in such a way that the offset provided on one side is exactly the opposite of the picture the offset made on the other hand represents on the central cross-section of the heat exchanger based. If special conditions have to be met on the entry and exit side, then the staggered arrangement of the tube sheets can also be carried out differently on the two sides.

On the round or hexagonal tube sheets, which are designed as perforated plates, are followed by the collector hoods, which in turn are equipped with Outlet nozzles for the medium flowing in the pipes are connected. The hoods have either hemispherical shape (with round tube sheets) or they go from the hexagonal shape (with hexagonal tube sheets) into the hemispherical shape, to which the inlet and outlet nozzles for the inner medium are attached connect.

The heat exchanger can be set up on or suspended from a support grid. Around To avoid thermal stresses, in the latter case the suspension is done by means of so-called »thermal sleeves «accomplished, c * n on the one hand at the entry resp. Outlet stubs and are attached to the outer guide jacket and on the other hand to the support grate.

When using the heat exchanger as a recuperator in the primary circuit of a gas-cooled high-temperature reactor is expediently that of the Incoming hot gas of low pressure around the pipes through the inner ducting of the turbine Assemblies out, while the high pressure gas to be heated is passed through the pipes.

In the drawing are two exemplary embodiments of the The heat exchanger according to the invention shown as Recuperator of a high-temperature reactor coupled with a helium turbine can be used. It shows

F i g. 1 shows a longitudinal section through a first recuperator in a standing arrangement and with im Cross-section of round building units,

F i g. 2 shows a section through the recuperator along the line AA in FIG. I,

3 shows a longitudinal section through a second Recuperator in a hanging arrangement, also with im Cross-section of the building units.

Fig. 1 shows a recuperative heat exchanger or recuperator in a standing arrangement, which is part of the primary circuit of a high-temperature reactor with helium turbine belongs and like all other components of the cycle in a vertical Shaft 1 is housed inside the prestressed concrete pressure vessel. The recuperator essentially consists from an outer conductive jacket 2, from a large number of structural units 3 with a round cross-section consisting of a support grid 4 and a support ring 5. The top is the Recuperator sealed by a plate 6 during the conclusion down through one towards the center inclined floor 7 is effected. The bottom 7 has a number of openings 8 for the passage of the outside Medium on. The support grid 4 on which the recuperator is set up consists of an outer ring 9, one Hub 10 and six spokes or support arms 11 together.

Each structural unit 3 has a tube bundle consisting of a large number of smooth, straight tubes {3, two tube sheets 14,15 into which the two ends of the Pipes are inserted, and an inner guide jacket 16, which is open at both ends. All tube bundles 13 have the same length. The tube sheets 14, 15 are followed by collector hoods 17, 18, which are hemispherical are trained. The collector hoods 17 are connected to inlet ports 19 for the inner medium, while 18 outlet nozzles 20 for this medium connect to the collector hoods. Within the Tube bundle 13, the individual tubes are held in place by brackets 21.

The structural units are arranged in a hexagonal grid in plan as in FIG. 2 is shown at three nested hexagons result from the above-mentioned formula n = 6 (l + 2 + 3) +1 = 37 structural units. In the free space between the outermost hexagon and the outer guide jacket 2 of the The recuperator is laid out in a number of smaller structural units 12, which are also used for heat transfer can be exploited.

The tube sheets 14 with the associated collector hoods 17 and the tube sheets 15 with the associated Collector hoods 18 are arranged offset against each other in the horizontal direction, namely in the Way that each of the tube sheets 14 and 15 of three adjacent, in plan an equilateral triangle

forming structural units 3 are on three different levels I, II, HI (see FIG. 2). As the inner guiding sheaths 16 have a smaller diameter than the tube sheets 14, 15, the structural units 3 can be very tight be pushed together. The closest arrangement results when the distance between the central axes of the Guide jackets 16 equal to or approximately equal to the sum of the radii of a guide jacket 16 and a tube sheet 14 and 15 respectively.

In FIG. 2, the structural units 3 inscribed digits I, II or III indicated in which level the tube sheets 14 or 15 of the corresponding structural unit are arranged. It's clear recognizable that adjacent tube sheets 14 or 15 are always in different planes.

As can be seen from FIG. I, the outlet nozzles 20 for the inner medium are extended downwards and Passed through the bottom 7 in a flow-tight manner. The outlet nozzles 20 each have above the bottom 7 a branch 25, and these branches are connected to risers (not shown). the Ends 27 of the extended outlet nozzles 20 are mounted in recesses 26 of the support grid 4.

Since the illustrated embodiment is the recuperator of a high-temperature reactor with a helium turbine concerns, the two media exchanging heat with one another are helium. That from the turbine incoming hot low-pressure gas is introduced from below through the openings 8 into the recuperator, which it shell side, d. H. The flow of the hot low-pressure gas is shown in FIG. 1 through Arrows indicated. After the helium has flowed through the structural units 3 in parallel, it occurs at the upper end emerges from the structural units 3 between the guide jackets 16 and the tube sheets 14 and passes through openings 22 in the outer guide jacket 2 in an annular gap 23 between this guide jacket and the (with a Lined) shaft 1. The cooled gas is then to one below the recuperator arranged precooler continued (not shown), which it also flows through on the shell side.

After the helium has passed the pre-cooler and in a compressor again at high pressure has been compressed, it is returned to the recuperator as high pressure gas.

The helium enters the tubes of the tube bundle 13 through the inlet connection 19 and the collector hoods 17, which it flows through from top to bottom, whereby it heats up after it passes through the tube sheet 15 and the Collector hoods 18 has passed through, the heated high pressure gas is fed through the branches 25 the outlet nozzle 20 led to the mentioned risers, the outside of the heating surface of the Recuperators lie. The helium flows through these lines back to the core of the reactor.

3 shows a recuperator in a hanging arrangement, which is also in a vertical shaft is housed within the prestressed concrete pressure vessel. It is shown here only the lining 31, with the the shaft is provided. The structural units 3, of which only one is complete for the sake of clarity shown have a round cross-section and consist of a straight tube bundle 13 and two Tube sheets 14 and 15 into which the two ends of the tubes

are used in. It also belongs to every structural unit 3 an inner guide jacket 16 which is open at both ends. All tube bundles 13 have the same length. Collector hoods close to the tube sheets 14, 15 17, 18, which are hemispherical. the

is collector hoods 17 are with inlet nozzle 19 for the inner medium connected, while at the collector hoods 18 outlet nozzle 20 for this Connect medium. Within the tube bundle 13, the individual tubes (not shown)

jii brackets housed in their position.

The layout of the structural units 3 again a hexagonal grid, as shown in Fig.2 for the recuperator is shown in an upright position. The tube sheet 14 with the associated collector house ben 17 and the tube sheet 15 with the associated collector hoods 18 are arranged such that they _{lie in three different horizontal planes I 1} II, III, with adjacent tube sheets - as in F i g. 1 descriptive »- are always offset from one another.

Because of this and because the inner guide jackets 16 one

smaller diameter than the tube sheets 14, 15 can have a larger number of structural units be accommodated in a given space.

Even with the recuperator in a hanging arrangement

can be in the edge zone between the outermost hexagon and at the same time the outer guide jacket forming lining 31 smaller structural units be laid, which in addition the heat transfer or the supply or return of the flowing in the pipes

Serving the medium.

The recuperator is suspended by means of a support grid 32 above the collector hoods 17 is arranged and has openings 33 for the inlet connection 19, only one of which is shown The connection between the inlet connection 19 and the support grid 32 is made with the aid of "thermal sleeves" 34 accomplished, which have the task of preventing the build-up of thermal stress. A similar one Connection 35 is also between the support grid 32 and the lining 31 is provided. Down is the one Recuperator sealed by a plate 36

The supply and discharge of the outer medium flowing through the inner guide jackets 16 can be performed in in a similar manner as in FIG. 1 shown on a repeated representation is therefore required in FIG. 3 waived

For this purpose 3 sheets of drawings

Claims (1)

Claim? Heat exchanger with circular or hexagonal Cross-section with a number of arranged inside an outer vane and closed Tube bundles combined straight tubes, each tube bundle from a guide jacket open on both sides is surrounded and together with this conductive jacket and the ι ο located at both ends associated tube sheet with header hoods forms a structural unit and the structural units in the Floor plan arranged in the hexagonal grid and adjacent tube sheets on the inlet and outlet side of the Tube bundles are offset from one another in the horizontal direction, characterized in that the offset of the tube sheets (14 or 15) in three different horizontal planes (I, II, III) is made, in such a way that each of the tube sheets (14 and 15) of three adjacent, im Plan of an equilateral triangle building units (3) on the different levels {I, II, III) are arranged, and that the distance between the central axes of the guide jackets (16) is equal to or approximately equal to the sum of the radii of a guide jacket (16) and a tube sheet (14 or 15) is