Patent Application
20220196331
The invention relates to a heat exchanger for indirect heat transfer between a fluid first medium and at least one fluid second medium.
Such a heat exchanger is used, for example, in natural gas liquefaction plants and has a shell space for receiving a first medium (refrigerant) and a plurality of tubes arranged in the shell space for receiving at least one second medium, which are wound around a core tube and form a tube bundle having a plurality of tube layers lying one above the other. Furthermore, the tube bundle has a plurality of spacers for supporting or mechanically stabilizing the tube layers, each of which is arranged in a tube bundle gap between two adjacent tube layers or in particular also in an innermost tube bundle gap between an innermost tube layer and an outer side of the core tube.
In this case, the number of spacers per tube bundle gap is generally constant so that the spacers for supporting the tube layers can be arranged one above the other in the radial direction of the tube bundle. In this way, the weight of all tube layers can be supported via the spacers without damaging the tubes of individual tube layers.
However, in a cross-sectional plane of the shell space perpendicular to the longitudinal axis (vertical) of the core tube or tube bundle, the spacers in each case reduce the free cross-sectional area of the shell space between the tube layers so that, due to the constant number of spacers per tube bundle gap (see above), the free cross-sectional areas between the inner tube layers or in the inner tube bundle gaps undergo a greater relative reduction than the free cross-sectional areas of the tube bundle gaps located further to the outside. As a result, the calculated pressure drop in the shell space would not be constant in the radial direction, but rather would be greater on the inside than further outside. However, since the flow through the gaps arises in reality in such a way that the same pressure loss prevails everywhere, a higher flow velocity results for the gaps lying further to the outside than for the gaps lying further to the inside, and therefore a higher dynamic and lower static pressure component. In the shell space, this can then lead to an incorrect distribution of the phase of the first medium guided in the shell space in the direction of the outer layers of the tube bundle.
Proceeding therefrom, the present invention is therefore based on the problem of creating a heat exchanger of the type mentioned at the outset which counteracts the aforementioned maldistribution.
This problem is solved by a heat exchanger having the features of claim 1, wherein advantageous embodiments of the invention are specified in the dependent claims and described below.
According to claim 1, it is provided that the spacers each have a thickness in the radial direction of the tube bundle, wherein the thicknesses of the spacers of a first tube bundle gap are in each case greater than the thicknesses of the spacers of a second tube bundle gap located further outward in the radial direction of the tube bundle, i.e., closer to the shell than is the first tube bundle gap.
In particular, a constant hydraulic diameter of the free flow cross-sections in the tube bundle gaps (between the tube layers and the spacers) can thereby be made possible or adjusted by reducing the radial thickness of the spacers in the radial direction from the core tube toward the shell.
The individual tubes are preferably wound helically onto or around the core tube 4. The tube bundle gap is in each case correspondingly designed in particular in the form of an annular gap.
It is preferably provided that the core tube extends along a longitudinal axis of the shell, wherein the longitudinal axis is vertically aligned when the heat exchanger is arranged as intended or ready for operation.
Furthermore, according to one embodiment of the invention, it is provided that the thicknesses of those spacers arranged in the same tube bundle gap are the same.
Furthermore, one embodiment of the invention provides that the spacers have more than two, in particular three to four, different thicknesses in the radial direction of the tube bundle, wherein the thickness of the spacers decreases or remains the same in the radial direction from the core tube to the shell from tube bundle gap to tube bundle gap. That is, in particular, in each case two or more tube bundle gaps adjacent to each other in the radial direction may have spacers of the same thickness, and only thereafter a decrease in thickness takes place (at the transition to the next tube bundle gap located further outward). That is, the thickness does not necessarily have to decrease from tube bundle gap to tube bundle gap but may also decrease outwardly in a stepwise manner.
Furthermore, according to one embodiment of the invention, it is provided that the thickness of the spacers decreases in the radial direction from the core tube to the shell from tube bundle gap to tube bundle gap. Here, the thickness of the spacers towards the outside (in the radial direction) thus decreases strictly monotonically.
Furthermore, one embodiment of the invention provides that the spacers are designed as longitudinally extending webs, each extending in a longitudinal direction. The spacers or webs can have a rectangular cross-section perpendicular to the longitudinal direction, which has said thickness, and a width perpendicular thereto (in the circumferential direction of the tube bundle).
Furthermore, one embodiment of the invention provides that the longitudinal direction of the respective spacer runs parallel to the core tube or to the longitudinal axis of the shell/core tube.
Furthermore, according to one embodiment of the invention, it is provided that the respective spacer extends along the core tube or the longitudinal axis over an entire length of the tube bundle.
Furthermore, it is provided according to one embodiment of the invention that the spacers are arranged equidistantly relative to one another in the circumferential direction of the tube bundle in the respective tube bundle gap.
Furthermore, according to one embodiment of the invention, it is provided that the spacers are grouped in such a way that a plurality of spacers for supporting the tube layers are arranged one above the other in a radial direction of the tube bundle.
Furthermore, one embodiment of the invention provides that the number of spacers in the each tube bundle gap is the same.
Further features, advantages and embodiments of the invention will be explained below with reference to the figures.
The figures show:
The tube bundle 15 has a plurality of tubes 10, wherein the tubes 10 are each wound around or onto a core tube 20 arranged in the shell space I, at least sectionally like a helical line, said core tube extending along the longitudinal axis Z so that a plurality of tube layers 101, 102, 103, 104 are formed which lie one above the other in the radial direction R of the tube bundle 15 or of the core tube 20. The radial direction R is in each case orthogonal to the longitudinal axis Z and points outwardly from the longitudinal axis Z toward the shell 2. In order to admit at least one second medium M′ into the tube bundle 15, the tubes 10 are in fluidic connection with at least one connecting piece 5 provided on the shell 2. Furthermore, at least one connecting piece 6 is provided on the shell 2 to withdraw the at least one medium M′ from the tube bundle 15. In order to introduce different second media M′, the tube bundle 15 can also be divided into tube groups, each of which is assigned an inlet or connecting piece 5 and an outlet or connecting piece 6.
Furthermore, the tube bundle 15 can be surrounded by a cylindrical skirt 7 in order to suppress a bypass flow past the tube bundle 15.
For mechanically stabilizing the tube bundle 15 or the individual tube layers 100, 101, 102, 103, several spacers 30 are provided (see in particular
The spacers 30 can support the weight of the individual tube layers 100, 101, 102, 103 via the spacers 30. A constant number of spacers 30 are therefore preferably provided in each tube bundle gap 200, 201, 202, 203 so that the spacers 30 can be arranged one above the other in the radial direction R.
In the prior art, however, said constant number of spacers 30 per tube bundle gap 200, 201, 202, 203 causes the relative reduction of a free cross-sectional area F, that is oriented transversely to the longitudinal axis Z, of the respective tube bundle gap 200, 201, 202, 203 due to the spacers 30 arranged one above the other in the radial direction R to be larger closer to the core tube 20 than in the case of tube bundle gaps located further outwardly. Close to the core tube 20, this leads to a greater pressure drop on the shell space side in the tube bundle 15 than in the case of regions or tube bundle gaps located further to the outside in the radial direction R.
In order to be able to influence or compensate for this pressure drop in a controlled manner, it is provided according to the invention (see
According to one embodiment, it can be provided that the spacers 30 have more than two, in particular three to four, different thicknesses D in the radial direction R of the tube bundle 15, wherein the thickness D of the spacers 30 decreases or remains the same in the radial direction R from the core tube 20 toward the shell 2 from tube bundle gap to tube bundle gap. That is, in particular, in each case two or more tube bundle gaps adjacent to each other in the radial direction R can have spacers 30 of the same thickness, and only thereafter is there a decrease in the thickness D so that there will be a stepwise decrease in the thicknesses D to the outside. Alternatively, it can be provided according to
The spacers 30 preferably take the form of longitudinally extending webs 30 (see
In the circumferential direction U of the tube bundle 15, the spacers 30 are arranged in the respective tube bundle gap 200, 201, 202, 203 preferably equidistantly to one another.
Due to the reduction of the thicknesses D of the spacers 30 in the radial direction R of the tube bundle, the free cross-sectional area F of the further outer tube bundle gaps (e.g., 202, 203) can be reduced or can be matched to the free cross-sectional areas F of the tube bundle gaps (e.g., 200, 201) lying more inwardly, which counteracts the shell-side maldistribution of the first medium or of the refrigerant.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2019 002 704.3 | Apr 2019 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/025151 | 3/31/2020 | WO | 00 |
