阅读说明：本技术 处理诸如海水的供给物的板式热交换器、热交换板和方法 (Plate heat exchanger, heat exchanger plate and method for treating a feed such as seawater ) 是由 M·安德尔松 于 2020-04-28 设计创作，主要内容包括：本发明涉及一种用于热交换器的板,该热交换器用于在第一介质与第二介质之间的热交换,该板限定热传递区域,该热传递区域包括交错布置的脊和谷的波纹状热传递图案。热传递区域限定用于第一介质的第一热交换表面和用于第二介质的相反的第二热交换表面。第一热交换表面限定用于第一介质的曲折流径。曲折流径分为在第一热交换表面的上部部分中横向延伸的上部流动通道、在第一热交换表面的下部部分中横向的下部流动通道以及在上部流动通道与下部流动通道之间的在第一热交换表面的中间部分中横向延伸的至少一个中间流动通道。(The present invention relates to a plate for a heat exchanger for heat exchange between a first medium and a second medium, the plate defining a heat transfer area comprising a corrugated heat transfer pattern of alternating ridges and valleys. The heat transfer zone defines a first heat exchange surface for a first medium and an opposite second heat exchange surface for a second medium. The first heat exchange surface defines a tortuous flow path for the first medium. The tortuous flow path is divided into an upper flow channel extending transversely in an upper portion of the first heat exchange surface, a lower flow channel extending transversely in a lower portion of the first heat exchange surface and at least one intermediate flow channel extending transversely in an intermediate portion of the first heat exchange surface between the upper and lower flow channels.)

1. A plate for a heat exchanger for heat exchange between a first medium and a second medium, the plate defining:

a longitudinal axis extending between the bottom edge and the top edge of the plate,

a transverse axis extending between two substantially parallel side edges of the plate,

a heat transfer region comprising a corrugated heat transfer pattern of alternating ridges and valleys, first and second adjacent ones of the ridges extending obliquely relative to the longitudinal axis and the transverse axis, the heat transfer region defining a first heat exchange surface for the first medium and an opposite second heat exchange surface for the second medium,

a first inlet for said first medium,

a first outlet for said first medium,

a second inlet for said second medium, and

a second outlet for said second medium,

whereby the first heat exchange surface defines a tortuous flow path for the first medium between the first inlet and the first outlet, the tortuous flow path being divided into an upper flow channel extending along the transverse axis in an upper portion of the first heat exchange surface, a lower flow channel extending along the transverse axis in a lower portion of the first heat exchange surface, and at least one intermediate flow channel extending along the transverse axis in an intermediate portion of the first heat exchange surface between the upper and lower flow channels.

2. The plate of any of the preceding claims, wherein the flow channels are positioned adjacent to each other along the longitudinal axis.

3. The plate, according to claim 2, wherein said first inlet is positioned adjacent to said first outlet.

4. The plate, according to any of the preceding claims, characterized in that it defines

An evaporation section arranged to allow at least a portion of the feed to evaporate,

a separation section arranged to separate a non-evaporated portion of the feed from an evaporated portion of the feed,

a condensing section arranged to condense an evaporated portion of the feed,

whereby the second heat exchange surface is formed in the evaporation section and/or the condensation section.

5. The plate according to any of the preceding claims, wherein the first medium is a heating medium and the second medium is a supply to be evaporated.

6. The plate, according to claim 5, wherein said upper channel is connected to said first inlet and said lower channel is connected to said first outlet.

7. The plate according to any one of claims 1-4, wherein the first medium is a cooling medium and the second medium is a vapour to be condensed, the lower channel being connected to the first inlet and the upper channel being connected to the first outlet.

8. A plate according to any of the preceding claims, wherein a cross-corrugated pattern is formed when the first heat exchange surfaces of the plate are juxtaposed with the first heat exchange surfaces of the same plate.

9. The plate of claim 8, wherein the cross-corrugated pattern defines a higher flow resistance with respect to the first medium in the upper channel along the transverse axis when compared to the middle channel.

10. The plate according to any one of claims 8-9, wherein the cross-corrugated pattern defines a lower flow resistance with respect to the first medium along the transverse axis in the lower channel when compared to the intermediate channel.

11. The panel as in any one of the preceding claims, wherein first and second adjacent ones of the ridges define a greater angle in the upper channel relative to the transverse axis than in the intermediate channel.

12. The panel as in any one of the preceding claims, wherein first and second adjacent ones of the ridges define a smaller angle in the lower channel relative to the transverse axis than in the intermediate channel.

13. A plate heat exchanger for treating a feed, such as seawater, comprising a plate package comprising a plurality of heat exchange plates according to any one of the preceding claims arranged in a consecutive order with a gasket in between each of the plates, whereby for adjacent plates a first heat exchange surface faces each other and a second heat exchange surface faces each other.

14. The plate heat exchanger according to claim 14, wherein the tortuous flow path is defined by at least one barrier forming part of a guide for the flow of the medium between the first inlet and the first outlet.

15. A shim for a plate according to any one of claims 1 to 12, the shim defining the tortuous flow path.

Technical Field

The present invention relates to a plate heat exchanger, a heat exchange plate and a method for treating a supply, such as seawater.

Background

Since many years plants for desalination of sea water have been manufactured, wherein one or several plate groups of heat exchange plates form the main member in the process. SE-B-464938 discloses such a desalination plant comprising a plate pack arranged in a cylindrical vessel. The heat exchange plates do not have ports for steam, but instead a space outside the heat exchange plates is used as a flow path for steam (depending on the kind of process). The process used is based on the so-called falling film technique, in which a water film is distributed across the width of the plate and extends downwards on the plate. In plate evaporators of the falling film type, every second plate interspace constitutes an evaporation space, while the remaining plate interspaces constitute a space for a heat-dissipating medium. The container is a substantially cylindrical pressure vessel. In large installations comprising several plate groups, these may be arranged in the longitudinal direction of the cylinder. To a certain extent, even though several containers may not be included in the apparatus, the containers are limiting with respect to the size of the apparatus.

To improve the efficiency of the plant, it may be provided with multiple stages. One example of a multistage desalination plant can be found in US 5133837, US 5133837 discloses a multistage flash vessel in which seawater to be evaporated enters the bottom chamber of each stage vessel, with the vapor flowing up through demisters and channels, contacting the crater plates, and the condensate falling as a film along the plates and collecting in a condensate trough. US 6635150 discloses a distillation apparatus consisting of a plurality of cascaded basic units assembled alternately in thermal series.

At least for smaller or medium sized plants, the cost for the container is a large fraction of the total cost for the plant. The manufacture and installation of the container is complicated and time consuming. In addition, maintenance of the equipment and cleaning of the heat exchanger plates is difficult, for example because the plate package and the heat exchanger plates are only accessible after opening of the vessel.

A solution to the above problem can be found in international application WO 2006/104443 a1 assigned to Alfa Laval corporation AB. It discloses a plate heat exchanger for desalination. The heat exchanger has an evaporation section, a separation section, and a condensation section. The advantage of the above mentioned heat exchanger is that it does not require any containers, since the entire treatment of the seawater is performed in the plate package.

Opposite sides of the plates of the evaporation section and the condensation section define a heating section and a cooling section, respectively. A heating fluid is circulated in the heating section and a cooling fluid is circulated in the cooling section. Guides formed by barrier gaskets are used in the heating and cooling sections for causing the heating and cooling medium to flow through the entire heat transfer area of the respective heating and cooling sections. Even if the inlet and outlet are positioned adjacent to each other, the guide causes the flow to be distributed within the heat transfer area.

DE 19647185 describes a heat exchanger with a rod for guiding the flow in the flow channel.

EP 0611941B 1 describes a plate heat exchanger having plates provided with a plurality of parallel ribs which are offset from each other to form a meandering (meander) chamber.

US 9,228,784B 1 describes a plate heat exchanger with a flow channel having flow barriers of flow guides which overlap in the horizontal direction and thus form a meandering flow channel.

US 2016/0245591 describes a plate heat exchanger having at least one barrier forming part of a guide for the flow of a first medium during its passage between an inlet port hole and an outlet port hole.

WO 2010/013608 discloses a plate evaporator/condenser with a flow guide.

WO 2018/19174 discloses a heat exchanger with gasket strips for guiding the flow.

It is an object of the present invention to improve the flow and heat transfer between the heating/cooling volume and the opposite evaporation/condensation section, respectively.

Disclosure of Invention

The above object is achieved in a first aspect by a plate for a heat exchanger for heat exchange between a first medium and a second medium, the plate defining:

a longitudinal axis extending between the bottom edge and the top edge of the plate,

a transverse axis extending between two substantially parallel side edges of the plate,

a heat transfer region comprising a corrugated heat transfer pattern of alternating ridges and valleys, first and second adjacent ones of the ridges extending obliquely relative to the longitudinal and transverse axes, the heat transfer region defining a first heat exchange surface for a first medium and an opposite second heat exchange surface for a second medium,

a first inlet for a first medium,

a first outlet for the first medium,

a second inlet for a second medium, an

A second outlet for the second medium,

whereby the first heat exchange surface defines a meandering flow path for the first medium between the first inlet and the first outlet, the meandering flow path being divided into an upper flow channel extending along the transverse axis in an upper portion of the first heat exchange surface, a lower flow channel extending along the transverse axis in a lower portion of the first heat exchange surface, and at least one intermediate flow channel extending along the transverse axis in an intermediate portion of the first heat exchange surface between the upper and lower flow channels.

The heat exchanger is constituted by a plate package consisting of a number of heat exchanger plates arranged in series in groups having a first surface facing the first surface and a second surface facing the second surface, with gaskets in between. The opposing first surfaces define a first plate gap that defines a tortuous flow path exhibited by the shim positioned intermediate the plates. The plate itself defines a recess for the gasket.

The flow path in the first plate interspaces defines at least three strokes, meaning that the flow is forced by the gasket to follow a meandering flow path for at least three transverse passes. Each transverse pass defines a flow channel, and each plate defines one flow channel in communication with the inlet, one flow channel in communication with the outlet, and at least one flow channel providing fluid communication between the inlet and outlet flow channels. The channels are connected in parallel and in series. The channels thus define an upper flow channel, a lower flow channel and one or more intermediate flow channels between the upper and lower flow channels. The expressions upper, lower, etc. are to be understood on the basis of the orientation of the plate when in use.

The second surface is part of an evaporator or condenser formed in a second plate interspace between the second surfaces of the opposite plates. The evaporator has an inlet for a feed (being a liquid, such as seawater) and an outlet for a vapour (such as steam). The evaporator typically evaporates only a part of the liquid and thus also has an outlet for non-evaporated feed (e.g. brine). The condenser has an inlet for a vapor (such as steam) and an outlet for a liquid (such as fresh water). In the evaporator, the vapour outlet is positioned above the seawater inlet when the heat exchanger is in its normal use position, as the vapour flows upwards. Similarly, because the liquid flows downward due to gravity, the fresh water outlet is positioned below the vapor inlet for the condenser.

The longitudinal axis is understood to be substantially vertical when the heat exchanger is in its normal operating position. The transverse axis is therefore substantially horizontal when the heat exchanger is in its normal operating position, and the ridges and valleys project transversely with respect to both the longitudinal axis and the transverse axis. The opposing ridges touch at contact points, establishing a heat transfer pattern in the plate gap.

Increasing the number of strokes from a typical two stroke to three strokes or more increases the flow velocity if all other parameters are held constant, as the thermal length increases and the flow area (i.e., cross section) decreases. This will create more turbulence which in turn will increase heat transfer. An increase in flow velocity will also increase the pressure differential between the inlet and the outlet. A small pressure difference between the inlet and the outlet will cause maldistribution between the plate interspaces of the plate package. A large pressure difference between the inlet and the outlet will thus improve the flow distribution along the first plate interspaces of the plate package.

According to a further embodiment of the first aspect, the flow channels are positioned adjacent to each other along the longitudinal axis.

A tortuous flow path may thus be achieved allowing greater utilisation of the plates by allowing fluid to flow predominantly in a transverse direction, except for a small longitudinal portion at the interconnection between the channels.

According to a further embodiment of the first aspect, the first inlet is located adjacent to the first outlet.

In this way, the inlet and outlet conduits may be positioned adjacent to each other.

According to a further embodiment of the first aspect, the plate defines

An evaporation section arranged to allow at least a portion of the feed to evaporate,

a separation section arranged to separate a non-evaporated portion of the feed from an evaporated portion of the feed,

a condensing section arranged to condense an evaporated portion of the feed,

whereby a second heat exchange surface is formed in the evaporation section and/or the condensation section.

A three-in-one panel is achieved by allowing evaporation, separation and condensation to take place on the same panel. As stated above, the second surface is part of an evaporator or a condenser.

According to a further embodiment of the first aspect, the first medium is a heating medium and the second medium is a supply to be evaporated. In this way an evaporator is realized.

According to a further embodiment of the first aspect, the upper channel is connected to the first inlet and the lower channel is connected to the first outlet.

Thus, hot heating fluid from the inlet will transfer heat to the hot portion of the vapor, while the somewhat cooler heating fluid at the outlet, which has given up some heat to the feed, will transfer heat to the cooler feed (which is introduced at the feed inlet adjacent the bottom of the evaporation section). The heating fluid will also flow counter-currently with respect to the feed on the opposite side of the plate. However, it is also possible to have the heating fluid flow co-currently with respect to the feed by switching the inlet and outlet.

According to a further embodiment of the first aspect, the first medium is a cooling medium and the second medium is a vapour to be condensed, the lower channel being connected to the first inlet and the upper channel being connected to the first outlet.

Thus, cold cooling fluid from the inlet will transfer heat to the cold portion of the vapor, while the slightly hotter cooling fluid at the outlet, which has absorbed some heat to the vapor, will transfer heat to the hotter vapor (which is introduced at the vapor inlet adjacent the top of the condensing section).

According to a further embodiment of the first aspect, the cross-corrugated pattern is formed when the first heat exchanging surfaces of the plates are juxtaposed with the first heat exchanging surfaces of the same plates.

A cross-corrugated pattern is formed by the ridges and valleys when adjacent panels are placed face-to-face and adjacent ridges will meet at a contact point. This flow pattern will increase both heat transfer and flow resistance.

According to a further embodiment of the first aspect, the cross-corrugated pattern defines a higher flow resistance with respect to the first medium in the upper channel along the transverse axis when compared to the intermediate channel.

In this way, in the first plate interspaces, more time is allowed for the heat transfer between the majority of the evaporating fluid at the top of the evaporation section and the hot heating fluid. In the second plate interspaces a low pressure drop with respect to the vapour is achieved.

According to a further embodiment of the first aspect, the cross-corrugated pattern defines a lower flow resistance with respect to the first medium along the transverse axis in the lower channel when compared to the intermediate channel.

In this way, in the first plate interspaces, less time is allowed for heat transfer between the bulk of the liquid fluid at the bottom of the evaporation section and the cooler heating fluid. Because the fraction of vapor is small, the pressure drop in the second plate interspaces is insignificant.

According to a further embodiment of the first aspect, the first and second adjacent ones of the ridges define a greater angle relative to the transverse axis in the upper channel than in the intermediate channel.

In this way, a high flow resistance is achieved in the transverse direction when the cross-corrugated pattern is established. Conversely, a lower flow resistance is achieved in the longitudinal direction.

According to a further embodiment of the first aspect, the first and second adjacent ones of the ridges define a smaller angle relative to the transverse axis in the lower channel than in the intermediate channel.

In this way, a lower flow resistance is achieved in the transverse direction when the cross-corrugated pattern is established. Conversely, a higher flow resistance is achieved in the longitudinal direction.

The above object is in a second aspect achieved by a plate heat exchanger for treating a feed, such as seawater, comprising a plate package comprising a plurality of heat exchanger plates according to any one of the preceding claims arranged in a consecutive order with a gasket in between each of the plates, whereby for adjacent plates the first heat exchange surfaces face each other and the second heat exchange surfaces face each other.

The spacers in the first plate interspaces with the first heat exchange surfaces facing each other are of a first type defining a heating section, a cooling section and a separating section, and the spacers in the second plate interspaces with the second heat exchange surfaces facing each other are of a second type defining an evaporation section, a condensation section and a separating section. A plate heat exchanger according to a second aspect utilizes a plate according to the first aspect.

According to a further embodiment of the second aspect, the tortuous flow path is defined by at least one barrier forming part of a guide for the flow of media between the first inlet and the first outlet.

The above object is in a third aspect achieved by a gasket for a plate according to the first aspect, the gasket defining a tortuous flow path.

Drawings

Figure 1a shows a heat exchanger plate according to the invention.

Figure 1b shows the opposite side of the heat exchanger plate of figure 1 a.

Fig. 2 shows a corrugated pattern of cooling sections.

Fig. 3a shows a corrugated pattern of heating segments.

Figure 3b shows the opposite side of the heat exchanger plate of figure 3 a.

Detailed Description

Figure 1a shows a heat exchanger plate 10 according to the invention. The plate 10 is corrugated. The plate 10 extends along a longitudinal axis (L), which is vertical when the plate is in its position of use, and a transverse axis (T), which is horizontal when the plate is in its position of use. The heat exchanger plates 10 may be stacked together with identical plates to form a plate package. The plate 10 defines first and second corrugated opposite surfaces arranged in groups such that the first surface faces the first surface of an adjacent plate and the second surface faces the second surface of an adjacent plate to form respective first and second types of gaps defined by shims and constituting the utility and process sides of the plate, respectively. This view shows the second surface, with the first surface formed on the opposite side of the plate (not visible here). This second surface defines an upper portion constituting the condensing section 12, a middle portion constituting the separating section 14, and a lower portion constituting the evaporating section 16.

The present panel 10 is a three-in-one panel, however, the principles according to the present invention are also applicable to other types of panels. The evaporation section 16 comprises a feed inlet 28 for introducing a liquid feed into the evaporation section. The feed inlet 28 is positioned at a lower portion of the evaporation section 16. The evaporation section 16 will be positioned opposite the heating section on the opposite side of the plate.

The evaporated feed will rise towards the separation section 14, which separation section 14 is positioned on both sides of the plate 10. Communication between the sides of the plate 10 is made through the apertures 30, 30'. In the separation section 14, the corrugations in the plates 10 drop into each other so that any droplets in the evaporation flow are captured. The droplets flow towards the edge of the plate and down towards the brine outlet 32, 32'.

The vaporized feed enters the upper portion of the condensing section 12. The opposite side of the plate 10 forms a cooling section and the evaporated feed is condensed in a condensation section 12. The condensate feed exits at the bottom of the condensing section 12 via a condensate outlet 34.

Fig. 1b shows a heat exchanger plate 10' according to the invention, which is the opposite side of the heat exchanger plate of fig. 1 a. The heating section 18 is positioned opposite the evaporation section 12 and is defined by a gasket 20. Heating section 18 defines a heating fluid inlet 22 for introducing heating fluid into heating section 18 and a heating fluid outlet 24 for emitting heating fluid from heating section 18. It is possible to switch the positions of the inlet 22 and the outlet 24 for allowing co-current flow. The heating fluid may be hot water, such as jacket water from an engine. Barriers 26, 26', 26 ″ in the form of shim elements are provided for causing the heating fluid flow to flow in a tortuous flow path from the inlet 22 to the outlet 24.

In this embodiment, four strokes are used (although more than four strokes may be used). Thus, the barriers 26, 26', 26 ″ are arranged such that four channels are formed in the transverse direction. In this way, the flow velocity of the heating fluid is increased compared to using only two strokes as in the prior art. Higher flow velocities increase heat transfer.

The heating fluid enters the top of the heating section 18 and flows in a lateral direction. Heat is transferred from the hot heating fluid to the supply on the opposite side, which will contain a large amount of vapor in the upper portion of the evaporation section. The heating fluid continues through the tortuous path and exits at the bottom of the heating section, with heat transfer taking place between the liquid feed near the inlet 28 and the heating fluid (which is now slightly cooled due to heat transfer with the feed).

The cooling section 36 is positioned opposite the condensing section 12. Cooling fluid is introduced via cooling fluid inlet 440 and discharged via cooling fluid outlet 38. The cooling fluid may be cold water, such as seawater. Barriers 26 "', in the form of shim elements, are provided for causing the heating fluid flow to flow in a tortuous flow path from the inlet 40 to the outlet 38, similar to the heating section 18.

In the cooling section 36, four strokes are also used, similar to the heating section 18 (although more than four strokes may also be used). In this way, the flow velocity of the cooling fluid is increased compared to using only two strokes as in the prior art. Higher flow velocities increase heat transfer.

The cooling fluid enters the bottom of the cooling section 36 and flows in a transverse direction. Heat is transferred to the cold heated fluid from the supply on the opposite side that will contain a large amount of condensate and a small amount of vapor in the lower portion of the evaporation section. The cooling fluid continues through the tortuous path and exits at the top of the cooling section 36 with heat transfer taking place between the vaporized supply near the inlet 40 and the cooling fluid (which is now slightly heated due to heat transfer with the supply).

It should be noted that in this embodiment, the heating fluid inlet and outlet are positioned in the center of the plate 10, and the heating fluid flows in two oppositely positioned paths from the center of the plate, while the cooling fluid inlet and outlet are positioned at the edges of the plate, so that all of the cooling fluid flows in a single path. However, the positions of the inlet and outlet depend on the corresponding conduit and can be considered arbitrary. Further, more or less than four strokes may be used, such as five strokes or three strokes. Four strokes means that the flow changes direction at least 3 times between the inlet and the outlet with a rotation of substantially 180 degrees.

Fig. 2 shows a corrugated pattern of the heat transfer area of the cooling section 36. When the corrugated patterns of two opposing plates are juxtaposed, a cross-corrugated heat transfer pattern is established. The corrugated pattern defines ridges and valleys, and opposing ridges of adjacent plates will be in contact in the plate package. The cooling fluid enters the inlet channel 36 'from the inlet 40 in a transverse direction and follows a tortuous path to the outlet channel 36' ″ and the outlet 38 via two intermediate channels, each labeled 36 ″. All channels 36', 36 "' extend in a transverse direction and the flow follows a transverse axis as shown by the arrows.

Fig. 3a shows a corrugated pattern for the heat transfer area of the heating section 18. The cross corrugated heat transfer pattern established by the two juxtaposed plates defines different patterns in the different channels 18', 18 "'. The heat transfer and flow resistance depend on the angle between the ridges of the cross-corrugated pattern and the flow direction. A large angle between the flow direction and the ridge results in a high flow resistance and a high heat transfer, the so-called high NTU (number of transfer units). The small angle between the flow direction and the ridge results in a low flow resistance and a low heat transfer, so called low NTU. The angle is understood to be greater than 0 degrees and less than 90 degrees.

The heating fluid enters the heating section 18 from above and flows in a transverse direction. The inlet channel 18' has ridges that form a large angle with respect to the cross flow and therefore a high NTU. A high NTU results in high heat transfer between the feed with high vapor content and low liquid content and the heating fluid. The outlet channel 18 "' has ridges that form a small angle with respect to the lateral flow of the heating fluid, thus low NTU. Here a low NTU is acceptable because the heat transfer coefficient is low on the evaporation side. The intermediate channel 18 ″ has an intermediate NTU pattern.

Fig. 3b shows a corrugated pattern for the heat transfer area of the evaporation section 16 (being the opposite side of the heating section 18). The liquid feed enters from inlet 28 in the lower portion of the evaporation section 16. The feed flows in the longitudinal direction and is discharged as vaporized feed into the separation section 14 at the top of the vaporization section 16.

The corrugations of the evaporation section 16 correspond to the corrugations of the heating section 18, i.e. the ridges correspond to valleys, etc. However, because the feed stream in the evaporation section 16 is perpendicular to the cooling fluid flow in the heating section 18, the high NTU channels in the heating section 18 will correspond to the low NTU channels in the evaporation section 16, and vice versa.

In the inlet flow channel 16' closest to the feed inlet 28, the feed will be mostly liquid. The inlet channel 16' has ridges that form a large angle with respect to the cross flow and therefore a high NTU. This is advantageous because a high NTU allows evaporation to start faster. In the two intermediate channels 16 ", intermediate NTU patterns are defined on both sides. The outlet channel 16' ″ is positioned at the top of the evaporation section 16. The outlet channel 16 ″ has ridges forming a small angle with respect to the longitudinal flow of the feed. A low NTU would be advantageous because the feed is mostly vapor at the top of the evaporation section 16 and the pressure drop should be kept low.

The panel is primarily intended for use in a freshwater generator where the feed is seawater and the condensate is freshwater. However, other applications are envisaged, such as the production of concentrated juices and the like. Further, the present application is not limited to the above embodiments, which are merely construed as examples.