Patent Application
20190072340
The invention relates to a heat exchanger as claimed in claim 1.
Such a heat exchanger serves for indirectly exchanging heat between a first medium and a second medium and has a shell, which surrounds a shell space for receiving a liquid phase of the first medium, and also at least one plate heat exchanger, which serves for indirectly exchanging heat between the two media, the at least one plate heat exchanger being arranged in the shell space such that it can be surrounded with a liquid phase of the first medium that is located in the shell space, and a distributing device, in particular in the form of a distributor channel, being arranged above the plate heat exchanger in the shell space for introducing into the shell space a two-phase stream of the first medium, the distributing device being in flow connection with an inlet provided on the shell, in particular in the form of an inlet nozzle, the distributing device or the distributor channel having at least one downwardly directed outlet opening, through which the two-phase stream can leave from the distributing device or the distributor channel into the shell space. Spatial terms such as “above” and “below” relate here and hereinafter to a heat exchanger arranged as intended or in operation.
A heat exchanger of the type described above is shown for example in “The standards of the brazed aluminium plate-fin heat exchanger manufacturer's association (ALPEMA)”, third edition, 2010, page 67 in FIG. 9-1. Usually, the shell is referred to as the “shell” and the plate heat exchanger is referred to as the “block”. Such a configuration of a heat exchanger is therefore also known as a “block-in-shell” heat exchanger (also commonly known as a “core-in-shell” or “block-in-kettle” heat exchanger).
A distributor channel of the type described above is also known from EP2472211A2.
Along with the first heat exchanging passages, which are open to the shell space, the plate heat exchanger has in particular closed second heat exchanging passages. The second medium in the second heat exchanging passages has no direct contact with the shell space. By contrast, the open first heat exchanging passages allow the first medium to pass through to the shell space, usually on a number of sides of the plate heat exchanger (for example on the underside and the upper side of the plate heat exchanger). The plate heat exchanger is in this case surrounded by a liquid bath of the first medium, which usually enters the plate heat exchanger on the underside as a liquid phase and leaves again on the upper side as a two-phase stream (from the outlet openings). The driving force for this is a temperature difference between the second medium in the closed second passages and the first medium in the open first passages. The heat exchanged from the second medium in the closed second passages to the first medium in the first passages has the effect that part of the liquid phase of the first medium in the open first passages evaporates. The plate heat exchanger in a core-in-shell heat exchanger is usually operated as a thermosiphon, i.e. in natural circulation.
The feeding in of the two-phase stream of the first medium into the separating space of the shell (“shell” or “kettle”) previously took place through one or more inlet nozzles on the side of the shell. In the present case, the separating space refers to the part of the shell space that is available for separating the gas phase of the first medium from the liquid phase of the first medium. The part of the shell space that is filled with the liquid phase of the first medium is referred to herein or is also referred to as the collecting space.
The distributor channel provided with outlet openings allows the entering two-phase stream to be distributed along the shell axis (horizontal distribution). A pre-separation (i.e. a coarse separation of the gas phase and the liquid phase) already takes place in the distributor channel. The configuration of the distributor channel is aimed substantially at a controlled feeding in and distribution of the gas phase of the first medium in the shell space. Therefore, relatively high velocities when entering the separating space are sought.
An (independent) control of the liquid flow with respect to the velocity and direction when entering the separating space is not possible here, or only inadequately. Under unfavorable conditions, a relatively high flow velocity of the liquid may in particular have the effect that the liquid gets into undesired regions of the shell space, for example due to various deflections in the distributor channel or else on the shell. Such a region may be for example the previously described upper side of a plate heat exchanger. Under some circumstances, the operation of the plate heat exchanger or the plate heat exchangers may be adversely influenced as a result. Adverse effects may for example take the form of the bubbling layer/overflow height increasing due to the increased amount of liquid, so that the circulation is impaired, and also furthermore the circulation slowing down locally, since the liquid arriving on the top has an opposite direction of flow. Furthermore, local temperature fluctuations of the plate heat exchanger may result if the inflow into the shell space and the outflow from the plate heat exchanger are at different temperatures. Furthermore, the energy of the impinging liquid may cause liquid to splash up in the direction of the gas outlet nozzle and be entrained there.
Against this background, the invention is therefore based on the object of providing a heat exchanger of the type mentioned at the beginning with which the control of the liquid flow of the first medium is improved.
This object is achieved by a heat exchanger with the features of claim 1. Advantageous refinements of the invention are provided in the subclaims and are described below.
According to claim 1, it is in this case provided that the heat exchanger has an additional conducting device, which is arranged at least partially under the distributor channel and is designed for conducting the liquid phase of the first medium or two-phase stream leaving from the at least one outlet opening of the distributor channel, the at least one plate heat exchanger having an upper side, and the conducting device being designed to conduct the liquid phase of the first medium away from the upper side and/or past the upper side.
This advantageously makes it possible to control and direct the flow of the liquid phase of the first medium entering the shell space into the core-in-shell heat exchanger. Here it is possible in particular for the flow velocity of the liquid entering the separating space of a core-in-shell heat exchanger to be reduced by an appropriate design and positioning of the conducting device. The conducting device may in particular be provided with damping elements, which are designed for reducing the energy of the flow that is guided.
According to one embodiment of the invention, it is provided that the distributor channel extends along a longitudinal axis, in particular cylinder axis, of the shell, which in the case of a heat exchanger arranged as intended or in operation runs along the horizontal. The conducting device preferably likewise extends along this longitudinal axis.
According to one embodiment, it is in this case provided in particular that the conducting device is designed to conduct at least part of the liquid phase that has left the at least one outlet opening in a first spatial direction into a second spatial direction. In particular, the second spatial direction differs here from the first spatial direction (that is to say that a deflection of at least part of the liquid phase takes place), the second spatial direction in particular having a greater horizontal component than the first spatial direction or for example pointing toward the shell. In particular, the first spatial direction runs along or parallel to the vertical from the top downward.
The conducting device is in particular a non-pressure-bearing component, so that its cross-sectional shape can be advantageously freely designed substantially without any influence on the strength of the conducting device.
According to one embodiment of the invention, it is provided that the at least one plate heat exchanger has first heat exchanging passages for receiving the first medium and second heat exchanging passages for receiving the second medium, so that heat is exchangeable indirectly between the two media, and in particular the first heat exchanging passages are in flow connection with the shell space by way of outlet openings on the upper side of the at least one plate heat exchanger, so that the first medium can leave through the outlet openings into the shell space. Referred to a heat exchanger arranged as intended, the upper side of the plate heat exchanger preferably extends in a horizontal plane.
As already explained, it is provided that the conducting device is designed with respect to this upper side to conduct the liquid phase of the first medium away from the upper side and/or past the upper side of the at least one plate heat exchanger.
Furthermore, according to one embodiment of the invention, it is provided that the conducting device is designed to conduct the liquid phase of the first medium such that the liquid phase does not impinge on the upper side.
According to a further embodiment of the invention, it is provided that the conducting device has at least one plate-shaped conducting element, in particular in the form of a baffle. The at least one conducting element preferably extends along the longitudinal axis of the shell. In particular, the at least one conducting element has a curvature, the baffle having in particular a convex first side, which is facing the plate heat exchanger, and also a second side facing away from the first side, which is facing away from the plate heat exchanger and/or is facing the distributor channel. Instead of a curvature (or in addition), the conducting element may also have an inclination, so that the liquid phase of the first medium is conducted away from the upper side of the plate heat exchanger. According to one embodiment of the invention, the at least one baffle is also arranged such that the liquid phase that is leaving the distributor channel impinges on the second side and is guided along the latter away from the upper side of the at least one plate heat exchanger and/or past this upper side.
Furthermore, according to one embodiment of the invention, it is provided that the conducting device and/or the baffle extends over the entire distributor channel along the distributor channel or the longitudinal axis of the shell or just over a portion of the distributor channel.
Furthermore, the at least one conducting element may have a plurality of through-openings for the first medium, so that at least part of the first medium can pass through the at least one baffle or conducting element.
According to a further embodiment of the invention, it is provided that the conducting device and/or the at least one conducting element is fixed on the distributor channel and/or on the shell of the heat exchanger. The at least one conducting element may for example be fixed on the distributor channel and/or the shell by way of a carrier of the conducting device. Thus, for example, according to a refinement of the invention, the carrier may comprise a frame that is fixed on the distributor channel and/or on the shell, the at least one conducting element in particular being fixed on the frame.
According to one embodiment of the invention, the distributor channel described at the beginning of the heat exchanger according to the invention is fixed on the shell, the shell forming in particular a side wall of the distributor channel. That is to say that the distributor channel is set against an inner side of the shell that is facing the shell space, the distributor channel having for example a horizontally extending base, the one edge of which is fixed on the shell, while from the other (opposite) edge there is made to extend (for example vertically) a side wall that is in turn connected to the inner side of the shell.
Furthermore, the at least one conducting element extends along the distributor channel, in particular parallel to the distributor channel.
The at least one conducting element may in this case be arranged flush with respect to the vertical side wall of the distributor channel, so that an outer side of the side wall of the distributor channel goes over steplessly or substantially steplessly into the first side of the conducting element. However, between the distributor channel or the vertical side wall and the conducting element there may also be provided a gap, which is made to extend along the longitudinal axis of the shell and through which a gaseous phase of the first medium can pass into the separating space.
According to a further embodiment of the invention, the heat exchanger has in the shell space a filling height at which the liquid level of the bath (liquid phase of the first medium) is located during operation as intended of the heat exchanger, the heat exchanger also having in the shell space a separating unit forming a receiving space, for separating the gaseous phase of the first medium from the liquid phase of the first medium. The separating unit has in particular at least one upwardly directed receiving opening for introducing into the receiving space first medium falling out of the distributor channel, the upwardly directed receiving opening being arranged above or at the filling height, so that the gaseous phase of the first medium that is received in the receiving space can escape via the receiving opening into the shell space.
The arrangement of the receiving opening does not necessarily have to be referred to the filling height, but may alternatively or additionally also be referred to an upper side or upper edge of the plate heat exchanger or of the plate heat exchanger block. Preferably, in this respect an upper edge (referred to the vertical) of the receiving opening is preferably in the range of 0 mm to 100 mm, particularly preferably in the range of 0 mm to 50 mm, more particularly preferably in the range of 0 mm to 25 mm above the upper side or upper edge of the plate heat exchanger, the value 0 mm corresponding to the level of the upper side or the upper edge of the plate heat exchanger in the direction of the vertical.
According to a preferred embodiment, it is provided that the separating unit has a first side wall, facing the inner space. In this case, the first side wall may have at least one distributing opening, the at least one distributing opening preferably being arranged at least partially under the filling height, so that the liquid phase of the first medium can be introduced by way of the at least one distributing opening into the bath surrounding the heat exchanger. The at least one distributing opening or the number of distributing openings is/are preferably formed as vertically extending slits. Generally, the first side wall has a number of distributing openings.
As an alternative to this, the first side wall may however also be formed as an overflow wall. The first side wall is then made liquid-impermeable, i.e. it does not have any distributing openings, so that the liquid phase of the first medium flows over an upper edge of the first side wall into the collecting space.
In other words, the separating unit may be configured both as an overflow pocket and as a (liquid-)permeable pocket, i.e. the position and direction of the liquid outlet is in particular freely selectable.
Preferably, the separating unit is arranged laterally in relation to the plate heat exchanger, in a horizontal direction running perpendicularly to the longitudinal axis of the shell, and extends along (in particular parallel to) the plate heat exchanger or along the longitudinal axis of the shell.
Furthermore, the first side wall preferably has an inclination. In this case, the first side wall is inclined toward the plate heat exchanger, so that the horizontal cross-sectional area of the receiving space increases vertically from the bottom upward.
The said filling height should be understood in particular as meaning a desired height at which the liquid level of the liquid phase of the first medium is located during the operation of the heat exchanger as intended. During operation as intended, the plate heat exchanger may be completely immersed in the bath, but may also protrude out of the bath with an upper side. The region of the shell space that is located above the filling height or the liquid level of the liquid phase of the first medium serves for receiving the gaseous phase of the first medium, and is therefore also referred to as the separating space.
The filling height preferably lies with reference to the upper side (or upper edge) of the plate heat exchanger in a range of −500 mm to +100 mm, particularly preferably in a range of −300 mm to +100 mm, more preferably in the range of −300 mm to +50 mm, still more preferably in the range of −300 mm to +25 mm, still more preferably in the range of −300 mm to 0 mm. Here, the value 0 mm corresponds to the level of the upper side (see above). Negative values indicate that the filling height lies below the upper side/upper edge of the plate heat exchanger in the direction of the vertical.
Preferably, the separating unit is formed as an upwardly open channel, which (in the same way as the distributor channel) extends along the longitudinal axis of the shell. The separating unit is preferably arranged vertically under the distributor channel, so that the liquid phase of the first medium that is leaving the distributor channel can fall through the receiving opening of the separating unit into the receiving space of the separating unit.
Preferably, the separating unit has a second side wall, which lies opposite the first side wall and is in particular formed by a wall of the shell. The second side wall may however also be formed separately from the shell.
It is preferably also provided that the separating unit has a third side wall and a fourth side wall opposite the third side wall, the third and fourth side walls respectively connecting the first and second side walls to one another, and in particular the third and fourth side walls respectively having at least one side opening for letting out the liquid phase of the first medium and in particular running perpendicularly in relation to the longitudinal axis of the shell. Preferably, a plurality of side openings are formed in the end third and fourth side walls. The third and fourth side walls may however also be formed as an overflow wall and then do not have any side openings. It is also conceivable that the third and fourth side walls are absent and the separating unit is formed as open at the ends. Furthermore, the third and fourth side walls may have a lower upper edge than the first side wall.
The invention makes it possible in principle to control and direct the flow of the liquid entering the shell space, it being possible to reduce the flow velocity of the liquid entering the separating space of a core-in-shell heat exchanger. The conducting device according to the invention may in particular also be used in the case of inlet distributors other than the distributor channel represented. If a separating unit is used, the conducting device may also be used for the controlled feeding of the liquid to the separating unit and is preferably set up and intended for that.
One advantage of the invention is in particular that the configuration of the conducting device is variable. Thus, in principle, the conducting device can be produced from all suitable materials (such as for example aluminum, steel or plastic). A combination of suitable materials is also possible.
The conducting device may consist both of metal sheet and of further suitable elements, such as for example worked tubes, worked solid materials, castings or (extruded) sections. The combination of different elements is also possible.
Furthermore, the shape, size and number of the elements of a conducting device that are used may be dictated both by production-related aspects and process-related aspects. In particular, allowance may also be made here for particular installation-specific features. Each of the elements used may be individually designed.
If metal sheets (for example in the form of the at least one conducting element) are part of the conducting device, they may be solid, perforated or else slit. In this case, the metal sheets may be both flat and profiled.
As already described, apart from on the distributor channel, the conducting device may also be attached at another suitable location (for example on the shell). The way in which it is attached is freely selectable. Thus, the conducting device may for example be welded on, screwed on or adhesively attached.
Furthermore, the alignment of the conducting device is freely selectable, so that a corresponding distribution of the liquid phase over the shell space can be produced.
The conducting device may also be made without a frame, it of course also being possible for parts with and without a frame to be combined.
Further features and advantages of the invention are to be explained in the following description of figures of exemplary embodiments of the invention on the basis of the figures, in which:
As can be seen from
To the sides, the first and second heat exchanging passages 71, 72 can be closed off by so-called edge bars or terminating bars (side bars) 91. The second heat exchanging passages 72 are additionally closed off upwardly and downwardly by such terminating bars 91.
The components of the at least one plate heat exchanger 4, such as for example the separating plates 90, the fins 80, the side bars 91 and the manifolds 61, 63, 62, 64 (also referred to as headers) are preferably produced from aluminum. The separating plates 90, side bars 91 and fins 80 are preferably brazed to one another in a furnace.
When it rises up in the at least one plate heat exchanger 4, the first medium F1 is brought into an indirect heat exchange with the second medium F2, which is introduced into the second heat exchanging passages 72 of the at least one plate heat exchanger 4 by way of an inlet nozzle 51 or 57 and also a manifold (also known as a header) 61 or 63 adjoining thereto, and is guided there in particular in cross-flow in relation to the first medium F1, which flows in the first heat exchanging passages 71.
As a result, for example, the initially gaseous second medium F2 is cooled down and in particular liquefied, whereas the first medium F1 becomes warmer and is partially evaporated. A gaseous phase G1 of the first medium F1 thereby occurring collects in the separating space A above the at least one plate heat exchanger 4 and can be drawn off from there out of the shell or separating space A by way of an outlet nozzle 55 or 56 provided on the shell 2. The condensed second medium is drawn off from the second heat exchanging passages 72 by way of a manifold (or header) 62 or 64 of the at least one plate heat exchanger 4 and drawn off from the heat exchanger 1 by way of a nozzle 52 or 54 connected to the respective manifold 62 or 64.
The liquid phase L1 of the first medium F1 leaving together with the occurring gaseous phase G1 on the upper side 4a of the at least one plate heat exchanger 4 is preferably returned to the bath surrounding the plate heat exchanger 4.
As shown in
For introducing the first medium F1 into the shell space 3 of the heat exchanger 1, a distributing device 6, here preferably in the form of a distributor channel 6, is arranged above the plate heat exchanger 4 in the shell space 3, the distributor channel 6 surrounding an inner space 6a for receiving the liquid phase L1 of the first medium F1 and being in flow connection with an inlet 53, which is provided at an upper region of the shell 2. The distributor channel 6 is in this case fixed on an inner side of the shell 2 that is facing the shell space 3, the shell 2 forming a side wall of the distributor channel 6. The distributor channel 6 also has a base 6c, which is made to extend horizontally along the longitudinal axis of the shell 2 and the one edge of which is fixed on the shell 2, while from the other (opposite) edge there is made to extend vertically a side wall 6d that is in turn connected to the inner side of the shell 2. The base 6c of the distributor channel 6 has at least one downwardly directed outlet opening 6b (preferably, in principle a number of such outlet openings 6b are provided), through which the liquid phase L1 of the first medium F1 can leave from the distributor channel 6 into the shell space 3 in a first spatial direction R.
Arranged under the distributor channel 6 in the vertical direction there is then a conducting device 10, which is designed for conducting the liquid phase L1 of the first medium F1 that is leaving the at least one outlet opening 6b, the conducting device 10 in particular deflecting at least part of the liquid phase L1 that has left the at least one outlet opening 6b downwardly in a first (in particular vertical) spatial direction R into a second spatial direction R′, which preferably differs from the first spatial direction R. Here, the second spatial direction R′ has for example a greater horizontal component than the first spatial direction R. The deflection of at least part of the liquid phase L1 in this case preferably takes place so as to conduct the liquid phase L1 of the first medium F1 away from the upper side 4a or past the upper side 4a of the at least one plate heat exchanger 4. It is thereby ensured that the liquid phase L1 of the first medium F1 does not impinge on the upper side 4a of the at least one plate heat exchanger 4.
For this purpose, the conducting device 10 has in particular at least one plate-shaped conducting element 100, in particular in the form of a baffle, that extends along the longitudinal axis and butts substantially flush against the side wall 6d of the distributor channel, or possibly goes over into it. The at least one conducting element 100 has in this case a curvature in such a way that the at least one conducting element 100 has a convexly curved first side 100a, which is facing the plate heat exchanger 4, and also a second side 100b, which is facing away from the first side 100a, is concavely curved and is facing away from the plate heat exchanger 4 or facing the distributor channel 6, to be precise its base 6c. The at least one conducting element 10 is thus arranged such that at least part of the liquid phase L1 of the first medium F1 that is leaving the distributor channel 6 through the at least one outlet opening 6b impinges on the second side 100b and is conducted along it away from the upper side 4a of the plate heat exchanger 4 and introduced into the bath laterally in relation to the at least one plate heat exchanger 4.
The at least one conducting element 100 is fixed here both on the distributor channel 6 and on the shell 2 of the heat exchanger 1 by means of a frame 20.
Optionally, according to one embodiment of the invention, as shown in
For catching the first medium F1, the separating unit 208 has in this case an upwardly facing receiving opening 209, which is arranged under the distributor channel 6 and the opening plane of which extends perpendicularly to the vertical. By way of the receiving opening 209, the first medium F1, falling out of the distributor channel 6, passes into a receiving space 207 of the separating unit 208. The separating unit 208 is in this case formed as an upwardly open channel, which extends under the distributor channel 6, likewise along the longitudinal axis of the shell 2, the separating unit 208 preferably having a length along the longitudinal axis of the shell 2 that corresponds to the length of the distributor channel 6 along this longitudinal axis. The receiving space 207 of the separating unit 208 or the receiving opening 209 can therefore be charged with the first medium F1 over its entire length.
The separating unit 208 has a peripheral wall defining the receiving opening 209 and bounding the receiving space 207. The wall has in this case a first side wall 210, which is facing the shell space 3 or the plate heat exchanger 4 and lies opposite the plate heat exchanger 4 transversely to the longitudinal axis of the shell 2 in the horizontal direction. Lying opposite the first side wall 210 is a second side wall 213 of the separating unit 208, which is formed by the shell 2. At the end faces, the separating unit 208 has a third and a fourth side wall 214 (only one of these side walls 214 can be seen in
Preferably, the separating unit 208 and/or the distributor channel 6 are formed by one or more metal sheets and are welded or connected in some other suitable way to the shell 2. In particular, the first side wall 210 and also the third and fourth side walls 214 may be respectively formed by a planar metal sheet and suitably connected to one another (for example by welded connections, riveted connections, etc.).
For letting the liquid phase L1 of the first medium F1 out of the receiving space 207 of the separating unit 208, the first side wall 210 has in particular distributing openings 211. Furthermore, side openings 212 may also be provided in the end side walls 214, by way of which the liquid phase L1 of the first medium F1 can likewise leave into the collecting space V (only one side opening 212 is shown by way of example).
The wall of the separating unit 208 or the first, third and fourth side walls 210, 214 define(s) an upper edge of the separating unit 208 that borders the receiving opening 209 and is preferably arranged above the filling height 300 of the liquid phase L1 in the collecting space V. Correspondingly, the liquid phase L1 of the first medium F1 preferably passes from the receiving space 207 into the collecting space V only by way of the distributing or side openings 211, 212. The separating unit 208 may however also form a liquid-impermeable pocket, so that the wall of the separating unit 208 acts as an overflow wall and correspondingly the liquid phase L passes into the collecting space V by way of the receiving opening 209. Furthermore, the separating unit 208 may be formed as open at the ends, that is to say not have third and fourth side walls 214. It is also possible that the third and fourth side walls 214 have in the vertical a lower upper edge than the first side wall 210.
The distributing openings 211 may be formed in a slit-shaped manner along the vertical. Other opening cross sections are also possible The distributing openings 211 are preferably arranged equidistantly from one another over the entire length of the separating unit 208 along the longitudinal axis of the shell 2. According to
For drawing off the gaseous phase G1 of the first medium F1 from the separating space A, the shell 2 has at least one outlet nozzle 55 on an upper region of the shell 2. Furthermore, an outlet 59, which is intended for letting the liquid phase of the first medium F1 out of the collecting space V, is provided on a lower region of the shell 2. By means of an overflow wall 58, a minimum filling height of the first medium F1 in the collecting space V is ensured.
| Number | Date | Country | Kind |
|---|---|---|---|
| 14004422.3 | Dec 2014 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2015/002462 | 12/7/2015 | WO | 00 |
