EP3108145B1 - Rotary machine and method for heat exchange in a rotary machine - Google Patents

Description

The invention relates to a rotary machine for conveying a fluid and a method for the heat exchange in such a according to the preamble of the independent claim of the respective category.

Rotary machines, such as pumps, are used to convey fluid media in a variety of technological fields. In the hydrocarbon processing industry, pumps throughout the processing chain, which typically begins at the oil or gas field, play an important role and often need to operate under technically demanding conditions. So it is possible, for example, when pumping oil that the medium to be delivered is present under very high temperatures of up to 200 ° C. Such high temperatures place great demands on the pump and in particular on the mechanical seals in such a pump.

Mechanical seals are commonly used to seal the shaft which carries the impeller of the pump and which is driven by the drive unit, for example a motor. These seals should prevent leakage of the fluid to be delivered on or along the shaft. Typically, mechanical seals are configured as sliding or mechanical seals comprising a stator and a rotor. In this case, the rotor is rotatably connected to the shaft, while the stator is fixed relative to the pump housing so that it is secured against rotation. During the rotation of the shaft so slide the Rotor and the stator to each other, resulting in a high mechanical stress on these parts results. For the proper operation of such mechanical seals, it is necessary that these seals are not subject in the operating state to high thermal loads. Therefore, especially for those fluids that are conveyed under high temperature, the mechanical seals must be cooled. Too high a temperature in the region of the mechanical seal can lead to material degradation on the sliding surfaces or other parts of the seal, damage to the secondary seals, undesirable phase transitions in the fluid to be pumped or thermally induced changes to the shaft, eg. B. bending.

Conversely, in those applications where the fluid to be delivered is very cold, for example, in the cryogenic technique of conveying liquefied gases, the mechanical seals must be heated to ensure proper operation.

It must therefore be ensured, depending on the application, that the mechanical seal or its surroundings are cooled or heated, ie kept in the correct temperature range via a heat exchange.

For this heat exchange in mechanical seals, ie the removal or the supply of heat, two possibilities are known in the prior art. In the first method, a heat exchange jacket is provided in the vicinity of the mechanical seal, which is a cooling jacket for dissipating heat or a heating jacket for supplying heat depending on the application. This jacket comprises a cavity, which surrounds, for example, the mechanical seal in the form of an annular space, and through which flows a fluid heat carrier, which supplies or dissipates the heat. The cavity has no connection to the space in which the mechanical seal is arranged so that there is no direct contact between the heat transfer medium and the mechanical seal. In this type of heat dissipation or heat usually external auxiliary systems, such. B. an external pump used to promote the fluid heat carrier in the cavity of the heat exchanger shell and to circulate the heat carrier.

The second possibility for the heat exchange is based on a direct contact of the mechanical seal with a fluid heat carrier and is commonly referred to as "flushing". Here, the mechanical seal or at least parts thereof is applied directly to a fluid heat carrier to thereby deprive her of heat or supply heat. For this type of heat exchange, it is known to circulate the fluid heat carrier in a closed circuit, which then comprises an external heat exchanger, at which the heat carrier emits the heat absorbed at the mechanical seal (cooling the seal), or at which the heat carrier the Absorbs heat that it supplies to the mechanical seal (heating the seal). The circulation of the heat carrier is driven by an external pump. Alternatively or in addition to the external pump, e.g. an impeller may be provided on the mechanical seal, which is driven by the rotation of the shaft and circulates the fluid heat carrier.

As an alternative to the closed flushing systems, it is also known to use open systems in which the heat carrier is not circulated in a closed circuit, but is taken from a source and discharged after passing through the pump, such as a sanitation. In these open systems can usually be dispensed with an external heat exchanger.

It is also known to provide for pumps two separate, independently operating cooling systems, one of which operates with a cooling jacket and one is designed as a flushing system. The two systems can be operated with different heat transfer media. However, such solutions are expensive in terms of apparatus, cost-intensive and usually have a large footprint.

Based on this prior art, it is therefore an object of the invention to provide a rotary machine with a new heat exchange system for a mechanical seal, which is apperativly simple and efficient cooling or heating even at high temperature loads by the heat or the cold of the fluid to be delivered ensures the mechanical seal. In particular, the rotary machine should be suitable be for high temperature applications where the fluid to be pumped is very hot. Furthermore, it is an object of the invention to propose a corresponding method for the heat exchange in a rotary machine.

The problem-solving objects of the invention are characterized by the features of the independent claims of each category.

According to the invention, therefore, a rotary machine for conveying a fluid is proposed with a drive unit for driving a shaft, with an impeller arranged on the shaft for conveying the fluid, with at least one mechanical seal for sealing the shaft, with a first and a second heat exchange system for cooling or for heating the mechanical seal, wherein the first heat exchange system is designed for direct loading of the mechanical seal with a fluid heat carrier, and the second heat exchange system comprises a heat exchange jacket, which is flowed through by a fluid heat carrier without direct contact with the mechanical seal. The first and second heat exchange systems form a common heat exchange system in which a common fluid heat carrier is circulated, and an impeller for circulating the fluid heat carrier is provided in the heat exchange system.

According to the invention it is therefore proposed to combine a heat exchange system, which operates on the principle of flushing, with a heat exchange system which works with a jacket to form a common overall system in which only a fluid heat carrier is circulated, the circulation of which is driven by the rotary machine itself , This heat exchange system thus combines the advantages of two heat exchange systems without the need for external circulation devices such as external pumps. This results in a very simple, compact and efficient solution, with which even large amounts of heat can be reliably removed from the mechanical seal area (cooling) or supplied to this area (heating).

Due to the high efficiency of the heat exchange, the rotary machine according to the invention is particularly suitable for high-temperature applications in which the fluid to be delivered can have temperatures of up to 200 ° C. or more.

In a preferred embodiment, the rotary machine is configured as a pump, wherein the drive unit comprises a motor which is arranged in a motor housing.

It is advantageous if the impeller is arranged in a pump housing, which is connected to the motor housing to form an overall housing, so that the pump including the motor is enclosed in a single housing. This compact and outwardly finished design allows the operation of the pump even under difficult environmental conditions.

Depending on the application, it may be advantageous if the rotary machine operates in a vertical arrangement. Then it is preferred that the drive unit is arranged in the normal use position above the pump unit, because then the drive unit is not burdened by the weight of the impeller.

A further advantageous measure with regard to the cooling, lubrication and protection of the drive unit, e.g. against the fluid to be delivered, it is when the motor housing is filled in the operating state with a barrier liquid.

The barrier liquid is then particularly preferably provided as the fluid heat carrier.

In an apperative aspect, it is advantageous if the impeller for the circulation of the heat carrier is driven by the drive unit and is preferably provided on the side facing away from the impeller of the drive unit.

According to a particularly preferred application, the rotary machine according to the invention is designed as a subsea pump.

A preferred use of the rotary machine is for conveying hot fluids whose temperature is at least 150 ° C.

According to the invention, there is further proposed a method for heat exchange in a rotary machine for conveying a fluid having a drive unit for driving a shaft, an impeller arranged on the shaft for conveying the fluid, and at least one mechanical seal for sealing the shaft, in which method the mechanical seal is cooled or heated with a first and a second heat exchange system, wherein the mechanical seal is acted upon directly by a fluid heat carrier by means of the first heat exchange system, and in the second heat exchange system flows through a heat exchange jacket of a fluid heat carrier without direct contact with the mechanical seal becomes. The first and second heat exchange systems are connected to a common heat exchange system in which a common fluid heat carrier is circulated, the fluid heat carrier being circulated through an impeller in the heat exchange system.

The advantages of this method correspond to those which have already been explained in connection with the rotary machine according to the invention.

In a preferred embodiment, the common heat exchange system is a cooling system.

The method is particularly suitable when the rotary machine is a pump, wherein the drive unit comprises a motor which is arranged in a motor housing, wherein the fluid heat carrier is used as a barrier liquid, with which the motor housing is filled and the impeller preferably from the drive unit is driven.

It is an advantageous measure if the fluid heat carrier is a water-based liquid, because these liquids are generally inexpensive, have sufficient heat capacity and are not harmful to the environment. In particular, mixtures of water and glycol are suitable as fluid heat carrier.

The inventive method is particularly suitable for high temperature applications in which the fluid to be delivered has a temperature of at least 150 ° C.

In particular, the method according to the invention is also suitable for applications in which the rotary machine is a subsea pump.

Further advantageous measures and embodiments of the invention will become apparent from the dependent claims.

Fig. 1:

eine schematische Darstellung eines Ausführungsbeispiels einer erfindungsgemässen Rotationsmaschine ausgestaltet als Pumpe, und

Fig.2:

eine schematische, teilweise geschnitte Darstellung einer mechanischen Dichtung mit Komponenten des Wärmetauschsystems.

In the following, the invention is explained in more detail both in terms of apparatus and in terms of process engineering with reference to an exemplary embodiment and with reference to the drawing. In the schematic drawing show, partly in section:

Fig. 1:

a schematic representation of an embodiment of an inventive rotary machine designed as a pump, and

Figure 2:

a schematic, partially cut view of a mechanical seal with components of the heat exchange system.

In the following description of a rotary machine according to the invention and a method according to the invention for heat exchange, reference is made by way of example to the case of application, which is particularly important in practice, in that the rotary machine is a pump. It is understood, however, that the invention is not limited to such cases, but also includes all other rotary machines which is provided for shaft seal a mechanical seal. The rotary machine may for example also be a compressor, a turbine or a generator.

Furthermore, with regard to the heat exchange with an exemplary character, it is assumed that the heat exchange is a cooling, in which heat is thus extracted from the system. It goes without saying that the invention also encompasses, in an analogous manner, applications in which the heat exchange is heating, ie applications in which heat is supplied to the system.

Fig. 1 shows in a very schematic representation of a rotary machine, which is designed as a pump and is generally designated by the reference numeral 1. The pump 1 comprises a drive unit 2 with a motor 21, which is arranged in a motor housing 22 and is designed here as an electric motor. The motor 21 has a motor shaft 25 which is the rotor of the electric motor.

The pump 1 further comprises a pump unit 3 with a pump housing 32, in which an impeller 31 is provided for conveying a fluid. The impeller 31 is arranged on a shaft 5, which is connected by means of a coupling 9 with the motor shaft 25, and thus driven by the motor 21 and in rotation about its longitudinal axis A (FIG. Fig. 2 ).

The motor housing 22 and the pump housing 32 are firmly connected to each other, for example, screwed together with a plurality of screws, and thus form an overall housing 4 for the drive unit 2 and the pump unit. 3
The shaft 5 and the motor shaft 25 are mounted in a conventional manner in a plurality of thrust bearings 7 and radial bearings 8.

The pump unit 3 further comprises an inlet 33 through which the fluid to be delivered by the action of the impeller 31 in the pump housing 32 is sucked, and an outlet 34 through which the fluid to be delivered is ejected.

To seal the shaft 5, two mechanical seals 6 are provided in the pump, namely a first, which seals the shaft 5 at the boundary between the pump unit 3 and the drive unit 2, so that the fluid to be conveyed is not along the shaft 5 in the drive unit. 2 can reach, and a second, which is provided according to the representation below the impeller 31 and the penetration of the fluid to be conveyed along the shaft 5 in a representation according to the impeller 31 provided below the storage space 35 prevents, in which one of the radial bearing 8 is arranged.

The exemplary embodiment of the rotary machine according to the invention described here is a multi-stage process pump for high-temperature applications in which the fluid to be delivered has very high temperatures of, for example, 150 ° C., 180 ° C., 200 ° C. or even more. Such high temperatures can occur, for example, in the natural gas or petroleum production, because there are oil fields in which the oil is present at temperatures of 200 ° C.

In particular, the embodiment described here is designed as a subsea (subsea) pump, which is mounted on the seabed and works there, z. B. for oil or gas extraction. Especially in such applications an extremely compact design and highest possible reliability and reliability is essential.

As usual in subsea applications, the pump 1 is configured in a vertical arrangement with overhead drive unit 2, ie in Fig. 1 the pump 1 is shown in its usual position of use. The motor housing 22 of the drive unit 2 is filled in a conventional manner with a barrier liquid 23, which serves to cool the mechanical and electrical components of the motor 21, and for lubrication. Also arranged below the impeller 31 storage space 35 is filled with the sealing liquid 23.

In Fig. 2 one of the mechanical seals 6 is shown in a highly simplified and schematic way. Mechanical seals are well known to those skilled in the art and therefore require no further explanation here. For that reason, and because it is sufficient for understanding, are in Fig. 2 many details such as the fixations of the parts of the seal 6 or secondary seals, z. B. O-rings, not shown.

Typically, mechanical seals are configured as sliding or mechanical seals that include a stator 61 and a rotor 62. In this case, the rotor is rotatably connected to the shaft 5, while the stator 61 with respect to the overall housing 4 or with respect to the pump housing 32 is fixed so that it is secured against rotation. Thus, during the rotation of the shaft 5, the rotor 62 and the stator 61 slide against each other.

For the proper functioning of the mechanical seals 6, it is essential that the seal 6 not be too hot (in high temperature applications) or not too cold (in cryogenic applications). For this purpose, a novel method for the heat exchange with the mechanical seal 6 is proposed according to the invention, which will now be described below with reference to the in the Fig. 1 and 2 illustrated embodiment will be explained.

There are provided a first heat exchange system 41 and a second heat exchange system 42 - here cooling systems - which are connected to a common heat exchange system 40. This integrated heat exchange system 40 serves to cool the mechanical seals 6.

The first heat exchange system 41 for cooling the mechanical seal 6 is a so-called flushing system, in which the mechanical seal 6 or at least parts thereof directly with a fluid heat transfer medium - is acted upon here - a coolant. Like this Fig. 2 shows, the mechanical seal 6 is arranged in a sealing chamber 63, which is designed for example as an annular space and the shaft 5 surrounds. In this sealing space 63, the heat transfer medium is introduced through an inlet opening 64. Further, an outlet opening, not shown on the Seal chamber 63 is provided, through which the heat carrier can leave the seal chamber 63 again. The outlet opening is arranged, for example, at 45 ° or rotated by 90 ° with respect to the longitudinal axis A to the inlet opening 64. During operation of the pump 1, the seal chamber 63 is substantially completely filled with the heat transfer medium, that is to say the same amount of coolant (heat transfer medium) flows through the inlet opening 64 into the seal chamber 63 as it leaves the seal chamber 63 through the outlet opening. The heat exchange - in this case the cooling - thus takes place by the direct contact of the heat transfer medium with the mechanical seal 6, in which the heat transfer medium of the seal 6 extracts heat and thus cools it.

The second heat exchange system 42 for cooling the mechanical seal 6 comprises a heat exchange jacket 421, which in the present embodiment is a cooling jacket 421. In this type of heat exchange, there is no direct physical contact of the mechanical seal 6 with the heat transfer medium, here the coolant. The cooling jacket 421 comprises a cavity 422, which is designed, for example, as an annular space and surrounds the entire shaft 5. An inlet 423 is provided, through which the heat carrier is introduced into the cavity 422 and an outlet 424, through which the heat carrier leaves the cavity 422. During operation, the cavity 422 is completely filled with the heat transfer medium which is circulated through the cavity 422. In this type of heat exchange or cooling there is no direct physical contact between the heat transfer medium and the mechanical seal 6.

How this particular out Fig. 1 it can be seen, the cooling jacket 421 is arranged in each case on the hotter side of the mechanical seal 6, ie on the side of the seal 6, in which the higher temperature prevails in the operating state. The pump housing 32 is filled in the operating state with the exception of the storage space 35 with the fluid to be delivered - so for example with the hot oil. In particular, the fluid to be delivered is also cooled in the vicinity of the seal 6 by the cooling jacket 421, that is, for example, in the gap 51 which leads to the seal 6. By this cooling of the fluid to be delivered in the immediate vicinity of the Mechanical seal 6 thus the heat input is significantly reduced by the fluid to be pumped into the seal 6, which corresponds to a cooling of the seal 6.

According to the invention, the first heat exchange system 41 and the second heat exchange system 42 are now connected to the integrated common heat exchange system 40. This has the consequence that there must be a common fluid heat carrier for the common heat exchange system 40. While with separate first and second heat exchange systems for these two separate systems and different fluid heat carrier could be used, so in the inventive solution, a common fluid heat carrier is necessary, which may be, for example, the same heat carrier as that of the first or the second heat exchange system.

As a fluid heat carrier for the common heat exchange system 40, the barrier liquid 23 is particularly preferably provided, which is also used for lubricating and cooling the motor 21 or the drive unit 2. This has the advantage that only a single liquid must be provided, which is used both as a barrier liquid 23 and as a fluid heat carrier for the heat exchange system 40. Especially for submarine applications, this measure has a very positive effect on the equipment required.

As a fluid heat carrier in particular water-based liquids such as a mixture of water and glycol are suitable.

Like this in Fig. 1 is shown, the common heat exchange system 40 is designed as a closed system, ie as a cooling system or a cooling circuit in which the fluid heat carrier is circulated. For the circulation of the heat carrier, an impeller 44 is provided, which is arranged on the motor shaft 25 and thus by the drive unit 2, especially by the rotation of the motor shaft 25 of the motor 21, is driven.

The impeller 44 conveys the heat transfer medium via a main line 45 to a heat exchanger 43, in which the heat carrier emits the heat absorbed at the mechanical seal 6 or in the drive unit 2 or in the storage space 35 and is thereby cooled. Downstream of the heat exchanger 43 now branch off a plurality of lines from the main line 45, first a first line 451, through which the heat transfer medium enters the motor housing 22, as indicated by the arrow on the line 451 symbolically. The heat carrier fills the motor housing and serves as a sealing liquid 23.

Further downstream, a second conduit 452 branches off from the main conduit 45, through which the heat carrier passes to the cooling system for the mechanical seal 6. The second conduit 452 branches again into a branch leading to the inlet 423 (FIG. Fig. 2 ) of the cooling jacket 421, and a branch leading to the inlet opening 64 of the sealing space 63. From the outlet opening (not shown) from the sealing space 63 and the outlet 424 of the cavity 422 of the cooling jacket 421, the fluid heat carrier reaches the return line 46 via respective lines which are brought together to line 461.

Finally, the main line 45 merges into a third line 453, through which the heat transfer medium reaches the cooling system for the lower mechanical seal 6 as shown. The third conduit 453 branches again into a branch leading to the inlet 423 (FIG. Fig. 2 ) of the cooling jacket 421, and a branch leading to the inlet opening 64 of the sealing space 63. In the exemplary embodiment described here, this sealing space 63 is connected to the storage space 35, so that the heat transfer medium can also reach the storage space 35 via the same line leading to the inlet opening 64 of the sealing space 63. From the outlet opening of the sealing space 63 and the outlet 424 of the cavity 422 of the cooling jacket 421, the fluid heat carrier reaches the return line 46 via respective lines, which are brought together to line 462.

Through the return line 46, the heat carrier passes back into the region of the impeller 44, which is the circulation of the heat carrier in the closed cooling circuit drives. Also, the introduced via the first line 451 in the motor housing 22 heat transfer is recirculated by the action of the impeller 44, as indicated by the arrow with the reference numeral 463.

The impeller 44 for the circulation of the fluid heat carrier is preferably on the side facing away from the impeller 31 of the pump unit 3 side of the drive unit 2 and. the side facing away from the impeller 31 of the motor 21 is provided.

In this way, the first heat exchange system 41 for the mechanical seals 6 and the second heat exchange system 42 for the mechanical seals 6 are connected to a common heat exchange system 40, thus forming an integral heat exchange system for the mechanical seals 6. At the same time, the common heat exchange system 40 also serves to supply the motor housing with the barrier liquid 23, which is identical to the fluid heat carrier.

As is customary in particular in subsea applications or in subsea pumps, the sealing liquid 23 is kept in the motor housing 22 at a higher pressure than the fluid to be pumped in the pump housing 32. The pressure of the sealing liquid 23 in the motor housing 22 is for example 20-25 bar higher as the pressure in the pump housing 32nd

The inventive method or the inventive rotary machine are suitable for a variety of applications. So they are particularly suitable for high temperature applications and especially for those in the submarine area. Designed as a pump, the rotary machine according to the invention can be used for conveying oil, gas, seawater or so-called "produced water". The pump can be configured as a single-phase, as a multi-phase or as a hybrid pump with the accordingly adapted thereto wheels. It is possible to design as well as single-stage as well as multi-stage pumps.

Especially for subsea applications, the proposed solution according to the invention by their integrated heat exchange system is an efficient, reliable, aperatively simple and compact way to cool or for heating mechanical seals.

As already mentioned, in a design of the pump as a subsea pump, a vertical arrangement is preferred in which the drive unit 2 is arranged above the pump unit 3. Of course, horizontal arrangements are possible in which the drive unit 2 and the pump unit 3 are arranged side by side. Such an arrangement is often preferred when the pump is not used in subsea operation but, for example, on land, or on ships or on drilling platforms.

As already mentioned, the rotary machine or the method according to the invention is also suitable for cryogenic applications, for example for the pumping of liquid gases in cryotechnology. In such applications, the mechanical seals are heated or heated by the heat transfer medium. The heat exchanger 43 then serves to supply heat to the heat carrier, which then transports this in a similar manner to the mechanical seals. In such applications, the heat exchange jacket of the second heat exchange system is then arranged on the colder side of the mechanical seal 6, that is to say on the side of the mechanical seal 6 which, in the operating state, faces the region of lower temperature.

Of course, the invention is not limited to pumps, but is also suitable for all other rotary machines in which mechanical seals are provided, such as compressors, turbines or generators.

Claims (13)

1. A rotary machine for conveying a fluid, having a drive unit (2) for driving a shaft (5), having an impeller (31) arranged at the shaft (5) for conveying the fluid, having at least one mechanical seal (6) for sealing the shaft (5), having a first and a second heat exchange system (41; 42) for cooling or for heating the mechanical seal (6); wherein the first heat exchange system (41) is configured for the direct application of a fluid heat carrier at the mechanical seal (6) and the second heat exchange system (42) comprises a heat exchange jacket (421) which can be flowed through by a fluid heat carrier without direct contact with the mechanical seal (6), characterized in that the rotary machine is configured as a subsea pump, and the first and the second heat exchange systems (41; 42) form a common heat exchange system (40) in which a common fluid heat carrier can be circulated and in that a fan wheel (44) is provided for the circulation of the fluid heat carrier in the heat exchange system (40).
2. A rotary machine in accordance with clam 1, which is configured as a pump, wherein the drive unit (2) comprises a motor (21) which is arranged in a motor housing (22).
3. A rotary machine in accordance with claim 2, in which the impeller (31) is arranged in a pump housing (32) which is connected to the motor housing (22) to form a common housing (4).
4. A rotary machine in accordance with any one of the preceding claims, in which the drive unit (2) is arranged above the pump unit (3) in the normal position of use.
5. A rotary machine in accordance with any one of the claims 2 to 4, in which the motor housing (22) is filled with a sealing liquid (23) in the operating state.
6. A rotary machine in accordance with claim 5, in which the sealing liquid (23) is provided as the fluid heat carrier.
7. A rotary machine in accordance with any one of the preceding claims, wherein the fan wheel (44) is driven for the circulation of the heat carrier by the drive unit (2) and is preferably provided at the side of the drive unit (2) disposed remote from the impeller (31).
8. Use of a rotary machine in accordance with any one of the preceding claims, for the conveyance of hot fluids whose temperature amounts to at least 150°C.
9. A method for the heat exchange in a rotary machine for conveying a fluid, the rotary machine having a drive unit (2) for driving a shaft (5), an impeller (31) arranged at the shaft (5) for conveying the fluid, as well as at least one mechanical seal (6) for sealing the shaft (5), in which method the mechanical seal (6) is cooled or heated with a first and a second heat exchange system (41; 42), wherein the mechanical seal (6) is directly applied with a fluid heat carrier by means of the first heat exchange system (41); and a heat exchange jacket (421) is flowed through by a fluid heat carrier without direct contact with the mechanical seal (6) in the second heat exchange system (42), characterized in that the rotary machine is configured as a subsea pump, and the first and the second heat exchange systems (41; 42) are connected to a common heat exchange system (40) in which a common fluid heat carrier is circulated and in that the fluid heat carrier is circulated in the heat exchange system by a fan wheel (44).
10. A method in accordance with claim 9, wherein the common heat exchange system is a cooling system.
11. A method in accordance with one of the claims 9 or 10, wherein the rotary machine is a pump, wherein the drive unit (2) comprises a motor (21) which is arranged in a motor housing (22), wherein the fluid heat carrier is used as a sealing liquid (23) with which the motor housing (22) is filled and wherein the fan wheel (44) is preferably driven by the drive unit (2).
12. A method in accordance with any one of the claims 9 to 11, wherein the fluid heat carrier is a water-based liquid.
13. A method in accordance with any one of the claims 9 to 12, wherein the fluid to be conveyed has a temperature of at least 150°C.

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