WO2020249340A1

WO2020249340A1 - Heat exchanger, method for producing a heat exchanger and power plant comprising such a heat exchanger

Info

Publication number: WO2020249340A1
Application number: PCT/EP2020/063124
Authority: WO
Inventors: Paul Girbig; Olaf Michelsson; Olaf Schmidt; Jürgen Voss
Original assignee: Siemens Aktiengesellschaft
Priority date: 2019-06-13
Filing date: 2020-05-12
Publication date: 2020-12-17
Also published as: US20220228809A1; EP3959478A1; DE102019208619A1

Abstract

The invention relates to a heat exchanger (8) which during operation in a flow direction is flown through by a medium to be cooled and by two different cooling media. The present invention also relates to a method for producing such a heat exchanger (8). Moreover, the invention relates to a power plant (1) having a generator (4) cooled by means of a generator cooling gas and a heat exchanger (8) cooling the generator cooling gas.

Description

Heat exchanger, method for producing a heat exchanger and power plant with such a heat exchanger

The present invention relates to a heat exchanger through which a medium to be cooled flows in one flow direction during its operation. The present invention also relates to a method for producing such a heat exchanger. In addition, the invention relates to a power plant with a generator cooled by a generator cooling gas and a heat exchanger cooling the generator cooling gas.

Power plants, such as gas turbines, steam turbines, combined gas and steam turbines, solar power plants or the like, comprise a large number of components that require cooling in order, on the one hand, to dissipate the resulting heat loss and, on the other hand, to increase the output of the power plant. This also applies to the generator used to generate electricity, which is usually cooled with generator cooling gas that has been recooled via a heat exchanger. The heat exchanger is usually connected to a closed cooling water system of the power plant, via which other heat exchangers are also supplied with cooling water, for example those for lubricating and / or sealing oil cooling, for cooling pumps or the like. The recooling of the cooling water of the cooling water circuit can be done in various ways, for example by means of fresh water flow cooling, circulation cooling using a cooling tower or air-cooled coolers, etc.

A possible achievable electrical power on the generator depends on the cold gas temperature of the generator cooling gas given for cooling the generator windings, that is to say the generator cooling gas temperature when entering the generator. The lower the cold gas temperature, the more mechanical energy can be converted into electrical energy in the generator. The generator cooling gas is recooled as previously described within a heat exchanger through which cooling water from the cooling water system of the power plant flows. The cold gas temperature of the generator cooling gas is thus coupled to the cooling water temperature of the cooling water flowing through the heat exchanger. The cooling water temperature, in turn, depends on the re-cooling of the cooling water and consequently cannot be reduced at will. This also places limits on the electrical power that can be achieved at the generator.

If performance-increasing measures on the turbine of the power plant lead to an increase in the mechanical power on the generator shaft, it would be desirable to provide improved cooling for the generator in order to be able to convert more power into electrical energy with it.

Based on this prior art, it is an object of the present invention to provide improved cooling, in particular improved generator cooling.

To solve this problem, the present invention creates a heat exchanger comprising a first lamella pack which has a plurality of first lamellae stacked in a stacking direction extending transversely to the flow direction, the first lamellae each being provided with a plurality of first through holes which are stacked direction are aligned with each other, at least one arranged in the flow direction adjacent to the first disk pack further disk pack, which has a plurality of stacked in the stacking direction second lamellae, the second lamellae each with a plurality of second

Through holes are provided which are aligned in the stacking direction with each other, first pipes, which lenpakets extend through the first through holes of the first lamellae of the first lamellae and are pressed with the first lamellae, second pipes, which extend through the second through holes of the second lamellae extend at least one further lamella set and connect with the second lamellae are pressed, wherein the first pipelines and the second pipelines are not fluidically connected to one another and are provided for the passage of a first and a second cooling medium, the cooling media being different from one another, and at least one connecting the first plate pack and the at least one further plate pack to one another Cover, which is placed in the stacking direction on an outer first lamella of the first lamella set and on the adjacent outer second lamella of the at least one further lamella set and covers these lamellae, where the at least one cover with corresponding to the first through holes of the first lamellae of the first

Lamellar set arranged and formed first through openings is provided through which the first Rohrlei lines are guided, and is provided with corresponding to the second through holes of the second lamellae of the at least one further lamella set arranged and formed two th through openings through which the two th pipelines passed are.

Such a heat exchanger is advantageous in that it can be operated with two different cooling media. The first cooling medium can, for example, be cooling water. A refrigerant that is recooled in a refrigeration machine can be used as the second cooling medium. If the medium to be cooled is generator cooling gas, its cold gas temperature when entering the generator is not limited by the degree of re-cooling of the cooling water of the cooling water system of the power plant. Rather, the cold gas temperature of the generator cooling gas can be further reduced by the heat exchange with the refrigerant flowing through the heat exchanger, so that it can be flexibly adapted to the cooling requirements of the generator if, for example, performance-enhancing measures are taken on the turbine. Another advantage of the heat exchanger according to the invention is that, due to the mechanical coupling of the plate packs through which the different cooling media flow, which via the at least At least one cover takes place, both lamella packs are given very good mechanical rigidity with a very inexpensive and small-volume structure at the same time, even if one of the lamella packs, for example, should only have a very low inherent rigidity due to a small overall depth. This is particularly important if an existing heat exchanger, in which the generator cooling gas has previously only been recooled using cooling water, is to be replaced by a heat exchanger according to the invention in order to lower the cold gas temperature of the generator cooling gas by additional cooling using a refrigerant. In such cases, the space available is dictated by the dimensions of the old heat exchanger and is very limited. Accordingly, there is hardly any space available for a disk pack through which a second cooling medium flows, which is why this second disk pack can often only be designed with a very small overall depth, which leads to low inherent rigidity.

According to one embodiment of the heat exchanger according to the invention, the first fins have a larger area than the second fins. In other words, the dimensions of the lamellae of the respective plate packs are adapted to the respective cooling medium.

The formation of the surface of the first lamellae is preferably different from the formation of the surface of the second lamellae. In this way, too, the disk packs can be adapted to the respective cooling medium.

The first lamellae and the second lamellae are advantageously made from sheet metal, for example from aluminum, in order to achieve good thermal conductivity.

According to one embodiment of the heat exchanger according to the invention, a distance between the first lamellae in the stacking direction is different from the distance between the second lamellae in the stacking direction, preferably greater. The first lamellae and the second lamellae can in accordance with the invention be produced from a sheet metal material that has a coating on one or both sides.

The first pipes are preferably connected to one another via U-shaped connecting lines and the first cooling medium flows through them one after the other and / or the second pipes are connected to one another via U-shaped connecting lines and the second cooling medium flows through one after the other.

The flow cross section of the first pipelines is different from the flow cross section of the second pipelines, preferably larger.

According to one embodiment of the present invention, the first pipelines and the second pipelines are made from a metallic material, preferably from copper, as a result of which good thermal conductivity is achieved.

The inner surfaces of the first pipelines and / or the inner surfaces of the second pipelines advantageously have a structure in order to enlarge them, which is conducive to better heat transfer.

Preferably, an arrangement pattern of the first through holes differs from the arrangement pattern of the second through holes.

The at least one cover is advantageously made from a metallic material, preferably from a metal sheet. This leads to a simple and inexpensive construction of the at least one cover.

The at least one cover advantageously grips the first disk pack and the at least one further disk pack opposite sides, whereby the mechanical rigidity of the construction is further increased.

According to one embodiment of the present invention, the first disk pack and the at least one further disk pack are connected to one another via at least one side part. Such a side part is also very beneficial to the mechanical rigidity of the construction.

Furthermore, the present invention provides a method for producing a heat exchanger designed according to the invention, in which the first lamellae and the second lamellae are produced simultaneously on a single lamella pressing device, for example using a lamella pressing tool which has both features of the first lamellae and features of the second lamella defined. In this way a very effective production of the heat exchanger according to the invention is achieved.

The first pipelines and the second pipelines are preferably expanded simultaneously in a pipeline expansion machine. Such a simultaneous expansion is also very conducive to effective production of the heat exchanger according to the invention.

In addition, the present invention creates a power plant with a generator cooled by a generator cooling gas and a heat exchanger according to the invention that cools the generator cooling gas.

Advantageously, the first cooling medium flowing through the heat exchanger is cooling water and the second cooling medium flowing through the heat exchanger is a refrigerant, for example tetrafluoroethane (R-134a) or carbon dioxide.

Further features and advantages of the present invention who based on the following description with reference to the accompanying drawings clearly. In it is

FIG. 1 shows a schematic view of a power plant according to an embodiment of the present invention;

FIG. 2 is a schematic view of an embodiment

a heat exchanger according to the invention of the power plant shown in Figure 1;

Figure 3 is a schematic side view in the direction of

Arrow III in Figure 2, which shows a first plate pack and a second plate pack of the heat exchanger, with struts and an upper and a lower cover are omitted for purposes of illustration;

Figure 4 is a plan view of a first lamella of a first

Lamella pack of the heat exchanger shown in Figure 2;

FIG. 5 shows a top view of a second lamella of a further lamella set of the heat exchanger shown in FIG. 2;

FIG. 6 shows a schematic view of a lamella production machine for producing the lamellae shown in FIGS. 4 and 5;

Figure 7 is a schematic perspective view of a

Lamella pressing tool of the lamella manufacturing machine shown in Figure 6; and

FIG. 8 shows a schematic view of pipeline expansion tools of a pipeline expansion machine. Figure 1 shows a power plant 1 according to an embodiment of the present invention. In the present case, the power plant 1 is a gas turbine power plant, which in principle can also be any other type of power plant. The power plant 1 comprises an air compressor 2, a gas turbine 3, a generator 4 and a transformer 5. During operation of the power plant 1, air compressed by the air compressor 2 is mixed with fuel in a known manner and the fuel-air mixture is ignited. The resulting combustion gas is fed to the gas turbine 3 and expanded there by driving a gas turbine rotor 6. The gas turbine rotor 6 drives the rotor 46 of the generator 4, which converts the kinetic energy into electrical energy. The transformer 5 transforms the electrical energy in such a way that it can be fed to a power supply network.

The generator 4 is supplied with direct current during operation via slip rings or a brushless exciter 47.

To cool the generator 4, generator cooling gas is used, which is circulated through a generator cooling gas circuit 7 by means not shown in detail. A heat exchanger 8 according to one embodiment of the present invention is provided for recooling the generator cooling gas. In the heat exchanger 8, the generator cooling gas is cooled on the one hand using cooling water that circulates in a cooling water circuit 9, and on the other hand by a refrigerant that circulates in a refrigerant circuit 10. In the present case, the cooling water circuit 9 is the so-called intermediate cooling water circuit of the power plant 1, to which further heat exchangers are also connected, via which, for example, lubricating oil, sealing oil, pumps and / or other components of the power plant 1 are cooled. The refrigerant circuit 10 through which the refrigerant flows comprises a refrigeration machine for recooling the refrigerant. Tetrafluoroethane (R-134a) is used here as refrigerant.

Alternatively, another refrigerant such as carbon dioxide can be used, to name just one example. During operation of the power plant 1, the generator cools gas from the generator 4, is cooled back in the heat exchanger 8 and then fed back into the generator 4. In the heat exchanger 8, the heat extracted from the generator cooling gas is transferred on the one hand to the cooling water flowing through the cooling water circuit 9 and on the other hand to the refrigerant flowing through the refrigerant circuit 10.

An essential advantage of the power plant 1 shown in FIG. 1 is that the cooling of the generator cooling gas flowing through the generator cooling gas circuit 7 does not only take place via cooling water, but also via a refrigerant. In this way, the cold gas temperature of the generator cooling gas when it enters the generator 4 can be set or controlled very flexibly and as required.

Another advantage is that the generator cooling gas is recooled by the cooling water and the Käl temittel in a single heat exchanger 8, since 8 space is saved by using a single heat exchanger. This is particularly important if an existing heat exchanger of a power plant, in which the re-cooling takes place solely using cooling water, is to be replaced by a heat exchanger according to the invention, since the available space is then defined by the dimensions of the old heat exchanger and is limited accordingly.

Figure 2 shows a possible design of a heat exchanger 8 according to the invention. The heat exchanger 8, which flows through the heat exchanger 8 in a direction of flow marked by the arrows 11, comprises a first lamella pack 12, which has a plurality of plates extending transversely to the flow direction, indicated by the arrow 13 marked stacking direction has stacked first lamellae 14. As shown in FIG. 4, the first lamellae 14 are each provided with a plurality of first through holes 15 which are aligned with one another in the stacking direction. Furthermore, the heat exchanger 8 comprises at least one in the flow direction adjacent to the first disk pack 12 arranged further disk pack 16, which has a plurality of ge in the stacking direction stacked second lamellae 17, the second lamellae 17 are each provided with a plurality of second through holes 18 which are aligned in the stacking direction with each other.

The first lamellae 14 and the second lamellae 17 are each made from sheet metal material, in the present case from aluminum, wherein the first lamellae 14 and / or the second lamellae 17 can be provided with a coating on one or both sides. The first lamellae 14 differ from the second lamellae 17 in that they have a larger area. On the other hand, apart from the first through holes 15, the surfaces of the first lamellae 14 are smooth in the present case, while the surfaces of the second lamellae 17 are structured. The structuring is defined in the illustrated embodiment by upwardly provided, laterally slotted raised areas 19, whereby the surfaces of the second lamellae 17 are enlarged and the flow of the generator cooling gas through the further lamellae pack 16 is influenced. It should be noted, however, that the design of the surfaces of both the first lamellae 14 and the second lamellae 17 can in principle vary as required. Another difference is that a distance a _± between the first lamellae 14 in the stacking direction is greater than a distance a2 between the second lamellae 17 in the stacking direction. In addition, the arrangement pattern of the first through holes 15 differ from the arrangement pattern of the second through holes 18 from one another, as can be seen from FIGS. 3 and 4.

The heat exchanger 8 further comprises first pipelines 20, which extend through the first through holes 15 of the first lamellas 14 of the first lamella set 12 and are pressed with the first lamellas 14, as well as second Rohrlei lines 21, which extend through the second through holes 18 of the second lamellae 17 of the at least one further lamella set 16 extend and are pressed with the second lamellae 17. The first pipelines are each connected to one another via U-shaped connecting lines 22 and the cooling water flows through one after the other, which enters the first disk pack 12 in the direction of the arrow 23 and exits it in the direction of the arrow 24. The two th pipes 21 are each connected via U-shaped connecting lines 25 and are successively traversed by the refrigerant that enters the further lamella pack 16 in the direction of the arrow 26 and exits it in the direction of the arrow 27. The first pipelines 20 and the second pipelines 21 are each made of a metallic material, in the present case copper, the flow cross section of the first pipelines 20 being greater than the flow cross section of the second pipelines 21. The inner surfaces of the first pipelines 20 and / or the inner surfaces of the second pipelines 21 can have a structure in order to increase their surface area.

The heat exchanger 8 also comprises an upper and a lower cover 28, which each connect the first plate pack 12 and the further plate pack 16 to one another. The covers 28 are placed in the stacking direction from below or from above on the outer first lamellae 14 of the first lamella set 12 and on the adjacent outer second lamellae 17 of the further lamella set 16 and cover these lamellae 14 and 17. The covers 28 are arranged and designed to correspond to the first through holes 15 of the first lamellae 14 of the first lamella set 12

Passage openings 29 through which the first pipelines 20 are passed and are provided with second passage openings 30 arranged and formed corresponding to the second passage holes 18 of the second lamellae 17 of the further lamella set 16, through which the second pipelines 21 are led. The covers 28 are made of a metallic material, each in the present case from a metal sheet made of aluminum. On the one hand, they have bevels 31 pointing in the direction of the plate packs 12 and 16, which enclose them on opposite sides, and on the other hand, outward-facing bevels 32 that serve to protect the pipelines 20, 21 or the connecting lines 22, 25 connecting them to one another. From the covers 28 are presently connected to each other via struts 33, which give the heat exchanger a good mechanical stiffness.

Figure 6 shows schematically a lamellar manufacturing machine 34 with a sheet metal roll receiving device 36 receiving a sheet metal roll 35, a sheet metal conveying device 37, a lamellar pressing device 38 which has an upper lamellar press tool 39 and a lower lamellar pressing tool 40, a lamellar transport device 41 and a lamellar stacking device 42.

During operation of the lamellar manufacturing machine 34, sheet metal from which the first lamellas 14 and the second lamellas 17 are to be made is unwound from the sheet metal roll 35 held on the sheet metal roll receiving device 36 via the sheet conveying device 37 and fed to the lamellar pressing device 38. In this, both the first lamellae 14 and the second lamellae 17 are formed in that the lamella pressing tools 39 and 40 are moved towards and away from one another. As shown in FIG. 7, the lamellar pressing tools 39 and 40 have different areas Al, A2, A3, A4, B1, B2, B3 and B4 which form the features of the lamellae 14 and 17. The areas marked with A form features of the first lamella 14 and the areas marked with B form features of the second lamella 17. The areas marked with the number 1 slit the sheet metal, the areas marked with the number 2 widen slotted areas, the areas marked with the number 3 pull the sheet deep. The first lamellae 14 and second lamellae 17 produced in this way in the lamella pressing device 38 are then used the lamella transport device 41 is moved to the Lamellenstapelein direction 42, where the first lamellae 14 and the second lamellae 17 are each stacked one on top of the other. The stacked fins 14 and 17 are then moved to a pipe expansion machine 43. There are the pipes 20 and 21, which meanwhile in the associated through holes 15, 18 of the stacked lamellas

14, 17 were simultaneously expanded using suitably shaped pipe expansion tools 44 by pressing the pipe expansion tools 44 in the direction of arrows 45 from above through the pipes 20, 21. In further steps, the covers 28, the struts 33 and the connecting lines 22, 25 are mounted.

Although the invention has been illustrated and described in more detail by the preferred exemplary embodiment, the invention is not restricted by the examples disclosed and other variations can be derived therefrom by the person skilled in the art without departing from the scope of the invention.

Claims

1. heat exchanger (8),

which is traversed by a medium to be cooled during its operation in one flow direction, comprising

a first lamella pack (12) which has a plurality of stacked in a transverse to the flow direction extending stacking direction stacked first lamellae (14), wherein the first lamellae (14) are each provided with a variety of first through holes (15) which align with each other in the stacking direction,

At least one further lamella set (16), which is arranged adjacent to the first lamella set (12) in the direction of flow and has a plurality of second lamellae (17) stacked in the stacking direction, the second lamellae (17) each having a plurality of second through holes (18) ) that are aligned in the stacking direction,

first pipelines (20) which extend through the first through holes (15) of the first lamellas (14) of the first lamellar set (12) and are pressed with the first lamellas (14),

second pipelines (21) which extend through the second through holes (18) of the second lamellas (17) of the at least one further lamellar set (16) and are pressed with the second lamellas (17), the first pipelines (20) and the second Rohrlei lines (21) are not connected to each other in terms of flow and are provided for the passage of a first and a second cooling medium, the cooling media being different from one another, and

at least one cover (28) that connects the first disk pack (12) and the at least one further disk pack (16) with each other, in the stacking direction on an outer first disk (14) of the first disk pack (12) and on the adjacent outer second disk (17) of the at least one further disk pack (16) is set and covers these lamellae (14, 17), the at least one cover (28) being provided with first through openings (29) arranged and formed corresponding to the first through holes (15) of the first lamellae (14) of the first lamella packet (12) is, through which the first pipelines (20) are guided, and is provided with corresponding to the second through holes (18) of the second lamellae (17) of the at least one further lamellae pack (16) arranged and formed second through openings (30), through which the second pipes (21) are passed.

2. Heat exchanger (8) according to claim 1,

characterized in that

the first lamellae (14) have a larger area than the two th lamellae (17).

3. Heat exchanger (8) according to claim 1 or 2,

characterized in that

the formation of the surface of the first lamellae (14) is different from the formation of the surface of the second lamellae (17).

4. Heat exchanger (8) according to one of the preceding claims,

characterized in that

the first lamellae (14) and the second lamellae (17) are made of sheet metal.

5. Heat exchanger (8) according to one of the preceding claims,

characterized in that

a distance (ai) between the first lamellae (14) in the stacking direction is different from the distance (a2) between the second lamellae (17) in the stacking direction,

preferably larger.

6. Heat exchanger (8) according to one of the preceding claims,

characterized in that

the first lamellae (14) and the second lamellae (17) are made from a sheet metal material which has a coating on one or both sides.

7. Heat exchanger (8) according to one of the preceding claims,

characterized in that

the first pipes (20) are each connected to one another via U-shaped connecting lines (22) and the first cooling medium flows through them one after the other and / or

that the second pipelines (21) are each connected to one another via U-shaped connecting lines (25) and the second cooling medium flows through one after the other.

8. Heat exchanger (8) according to one of the preceding claims,

characterized in that

the flow cross section of the first pipelines (20) is different from the flow cross section of the second pipelines (21), preferably larger.

9. Heat exchanger (8) according to one of the preceding claims,

characterized in that

the first pipelines (20) and the second pipelines (21) are made of a metallic material, preferably copper.

10. Heat exchanger (8) according to one of the preceding claims,

characterized in that

the inner surfaces of the first pipes (20) and / or the inner surfaces of the second pipes (21) have a structuring.

11. Heat exchanger (8) according to one of the preceding claims,

characterized in that

an arrangement pattern of the first through holes (15) is different from the arrangement pattern of the second through holes (18).

12. Heat exchanger (8) according to one of the preceding claims,

characterized in that

the at least one cover (28) is made from a metallic material, preferably from sheet metal.

13. Heat exchanger (8) according to one of the preceding claims,

characterized in that

the at least one cover (28) encloses the first disk pack (12) and the at least one further disk pack (16) on opposite sides.

14. Heat exchanger (8) according to one of the preceding claims,

characterized in that

the first disk pack (12) and the at least one further disk pack (16) are connected to one another via at least one strut (33).

15. A method for producing a heat exchanger (8) according to one of the preceding claims,

characterized in that

the first lamellae (14) and the second lamellae (17) are produced simultaneously on a single lamella pressing device (38).

16. The method according to claim 15,

characterized in that

the first pipelines (20) and the second pipelines (21) are widened simultaneously in a pipeline widening machine (43).

17. Power plant (1)

with a generator (4) cooled by a generator cooling gas and a heat exchanger (8) according to one of Claims 1 to 14 cooling the generator cooling gas.

18. Power plant according to claim 17,

characterized in that

the first cooling medium flowing through the heat exchanger (8) is cooling water and the second cooling medium flowing through the heat exchanger is a refrigerant.