EP2093515B1 - Component for a compact heating system - Google Patents

Abstract

The assembly has a set of heating circuits with an attachment for connecting the respective heating circuit to a vertical connection pair of a plate-type heat exchanger (12), where the connections are provided at a rear-side in an installation position. Each heating circuit has a centrifugal pump (15), and two pipe sections (19, 20) are vertically arranged next to each other in the installation position, and are flow conductively connected with each other by a connecting component (22) that is deflected around 180 degrees. A flow meter is arranged in the pipe section (19).

Description

The invention relates to a sub-assembly for a compact heating system according to the features specified in the preamble of claim 1.

Teilbaueinheiten of the aforementioned type are in compact heating systems to the prior art ( EP 1 528 330 B1 and EP-A-1 582 824 ). Such units or parts thereof, so-called sub-assemblies are used in compact heating systems to arrange the water-bearing components, fittings, pumps, valves, sensors and the like to save space and handle as a whole, ie to be able to do without the usual individual piping. Such compact heating systems, which serve both for space heating, ie for heating the heat transfer medium flowing in the space heaters and for generating hot process water, typically have a structural unit which comprises a plurality of the aforementioned components. Since the complete piping of all water-carrying lines within the compact heating system, as well as the inclusion of pump, valves, fittings and other components in a single injection molded part leads to highly complex and therefore expensive tools, so-called sub-assemblies are formed, which typically formed from a but less complex injection molded component are, for example, the back connected by a plate heat exchanger then form a jointly manageable and mountable assembly.

Because the space heaters are typically thermostat controlled, make temperature fluctuations in the heating circuit for space heating to the outside barely noticeable. In the domestic water heating, however, it is not only necessary to determine whether the hot water is flowing or not, but it is also appropriate to detect the amount to control the amount of heat transfer medium supplied via the plate heat exchanger can accordingly. The flow rate measurement in such heating systems, however, is problematic in several respects. On the one hand, a comparatively long and, if possible, straight measuring section is required for an exact measurement; on the other hand, the measuring principle must be designed such that the device operates without errors over a large number of years, which can be problematical in the case of mechanical measuring arrangements with moving parts.

Against this background, the invention has for its object to provide a generic sub-assembly that offers better ways of measuring and control in terms of hot water heating.

This object is achieved according to the invention by the features stated in the characterizing part of claim 1. Advantageous embodiments of the invention are specified in the subclaims, the following description and the drawing.

The sub-assembly according to the invention, which is intended for a compact heating system with two heating circuits and has two rear side mounting positions for connection to a vertical pair of connections of a plate heat exchanger and a centrifugal pump, according to the invention is designed so that two side by side and in the installed position substantially vertically arranged line sections are provided, which deflects by a flow through about 180 ° Component are conductively connected, wherein in one of these line sections, a flow meter is arranged.

The embodiment of the invention allows a comparatively long compared to the prior art wiring, in which the flow can calm and thus is particularly suitable for a flow meter.

The basic idea of the present invention is thus, on the one hand, to provide as long as possible and straight line sections for a suitable flow rate measurement, on the other hand not to significantly influence the compactness of the remaining structural unit and finally to design the construction so that less expensive tools are used to produce the corresponding injection-molded component have to. The fact that the two line sections are arranged side by side, they can be made with a suitable arrangement with drawing cores same direction of pull. In addition, the vertical arrangement of an upper space next to the pump is used, which would otherwise remain unused. By virtue of the component deflecting the flow through approximately 180 °, an advantageous embodiment of the subassembly, which will be described in more detail below, can optionally be carried out. Due to the fact that the flow is deflected by about 180 °, one of the line sections over its entire length can be used for flow rate measurement, whereas the other line section allows at least partial return of the flow and further routing within the sub-assembly.

The inventive construction of the sub-assembly is particularly for a working according to the vortex principle flow meter of advantage, in which the flow disturbed targeted by an obstruction into the flow obstruction and the forming behind the obstruction vibration by means of a pressure or differential pressure gauge is measured to thereby draw conclusions about the flow rate and thus the flow rate. This measurement principle is particularly predestined for the above purpose in a heating system, since it is largely insensitive to deposits, entrained in the heating water particles and the like, since it has virtually no moving parts. The differential pressure gauge used to detect the vibration is inexpensive to manufacture and long-term stable almost wear-free. The flow meter is advantageously arranged near the beginning in the upstream-side line section, so that this entire section of the service can serve exclusively for measuring the flow rate, which positively influences the accuracy of the measurement.

In this case, according to an embodiment of the invention, the upstream-side line section is arranged at a distance from the pump housing, i. the flow is first guided through the pipe section spaced from the pump housing, then deflected by 180 ° to pass through the pump housing adjacent line section. Therefore, an outflow-side line section is advantageously arranged adjacent to the pump housing, so that the two line sections are arranged at different distances next to the pump housing, preferably in installation position seen from the front in front of the plate heat exchanger.

Advantageously, the obstruction for the flow meter is formed integrally with the upstream line section, so that no separate component is needed for this purpose. In particular, when the upstream-side line section, as in the construction described below, is open on both sides, such obstruction can be made by means of tools with little effort by appropriate modification of the cores. The downstream or pressure or differential pressure sensor however, is inserted by means of a corresponding receptacle as a separate unit from the outside into the line, so that it can be quickly and easily replaced if necessary in case of a defect. Since this line section is advantageously located next to the pump housing and in front of the plate heat exchanger, it is particularly well accessible in the installed position.

The flow diverting by about 180 ° component will be formed in the simplest form as a kind of 180 ° elbow. According to an advantageous development of the invention, however, the subassembly can be supplemented in this area by a component which has at least parts of a flow rate regulator. Such a flow rate regulator is a particularly advantageous addition to the entire unit, since it allows the flow rate of service water can be controlled at the open sampling point, without complex sensors, motor and control electronics must be used. Mechanical flow rate regulators are state of the art and today can be provided comparatively inexpensive and small-scale. By means of such a mechanical flow regulator, the flow rate of the process water through the plate heat exchanger can be kept substantially constant regardless of the supply pressure. However, the embodiment of the invention is not limited to mechanical flow rate regulator, but such may possibly also be formed by an electromechanical, hydraulic or other flow rate regulator.

Advantageously, an externally operable control member for adjusting the flow rate is arranged in the flow-deflecting component. Since this area is particularly well accessible in the installation position at the front, such an actuator can advantageously be used after installation or during maintenance work to set the appropriate flow rate and is formed for example as a thumbscrew or handwheel.

According to a development of the invention, an aperture-like component is advantageously incorporated in the region of the housing division between the component deflecting the flow and a component forming the line segments, typically the plastic injection-molded component which forms the essential part of the partial structural unit, which is an elastic element, preferably an O-ring. Ring has. The arrangement in this area is particularly advantageous because such elastic elements typically cure over time and thus may need to be replaced. This can be done in such a simple manner in which the flow deflecting component is removed from the sub-unit, after which this iris-shaped component is not only clearly visible, but also easily accessible, since it is located in the housing division.

Advantageously, the line section, which has the flow meter, so advantageously the spaced apart from the pump housing arranged preferably straight out led down to the service water connection or forms this. The other line section, which merely serves to return the flow, then shoots advantageous to a connection of the heat exchanger, namely to the input-side service water connection.

The arrangement of the two juxtaposed line sections is advantageous in that they are arranged approximately vertically in the installed position in front of the plate heat exchanger and next to the centrifugal pump, since this area is not easily accessible for a well-accessible and otherwise for other components.

Since both the suction-side part of the pump and the line section adjacent to the pump have to connect to the connections of the plate heat exchanger lying directly above each other in the installation position, they can not usually be formed by simple transverse channels, since a certain offset is required. In order to realize this favorable tool technology is provided according to the invention to provide at least one, but preferably two arcuately following the plate heat exchanger channels, the arc direction is opposite, so that the desired offset takes place or the free end of the channels to the installation position directly above each other arranged connections of the plate heat exchanger arrives. Advantageously, one of the arcuate channels is provided on the suction side of the pump and the other arcuate channel is provided on the vertical line section, which leads from the flow-deflecting component to the heat exchanger. The connection is advantageous in that the lower for the service water and the upper for the heating water, ie for the return to the pump. This arrangement has the advantage that the water returning to the pump via the heat exchanger can flow up into the pump housing at the location where typically the air separator is arranged, so that the spatial arrangement assists the air separation.

According to one embodiment of the invention advantageously of the flow-deflecting component leading to the plate heat exchanger vertical line section on an opening which is conductively connected to the suction side of the pump or can be connected via a valve incorporated in the unit. About such an arrangement, a filling device can be realized without external line connections, so it can then be filled or refilled with hot water only by pressing the valve of the heating circuit.

According to one embodiment of the invention, this opening is formed as a channel and opens into a valve assembly in the bottom open valve chamber, which is provided or formed for receiving a valve body or a shut-off. It can then be advantageously incorporated either directly such a filling valve in the sub-assembly, but it can also be incorporated a shut-off to put this overflow out of function. Alternatively, a combination can be used, to the effect that the opening blocked off, but the access to the heating circuit is provided via a valve there, then expediently a corresponding connection piece for a hose or line is led to the outside.

Fig. 1

in perspektivischer vereinfachter Darstellung eine erfin- dungsgemäße Baueinheit in Einbaulage im Chassis einer Kompaktheizungsanlage,

Fig. 2

eine perspektivische Ansicht der Baueinheit,

Fig. 3

eine Draufsicht auf die Baueinheit,

Fig. 4

eine Ansicht von vorne auf die Baueinheit,

Fig. 5

eine Ansicht von der ein Einbaulage rechten Seite auf die Baueinheit,

Fig. 6

eine Ansicht von der in Einbaulage linken Seite auf die Baueinheit,

Fig. 7

die einen Bypass bildenden und die Teilbaueinheiten ver- bindenden Bauteile in perspektivischer Darstellung,

Fig. 8

eine Ansicht auf die Bauteile gemäß Fig. 7 in Einbaulage gesehen von vorne,

Fig. 9

einen Schnitt längs der Linie A-A in Fig. 8,

Fig. 10

eine perspektivische Ansicht des Druckreglers,

Fig. 11

den Druckregler gemäß Fig. 10 im Schnitt,

Fig. 12

den Stellkörper des Druckreglers in Ansicht,

Fig. 13

einen Längsschnitt durch die parallel nebeneinander ver- laufenden Leitungsabschnitte der ersten Teilbaueinheit,

Fig. 14

einen Längsschnitt durch die erste Teilbaueinheit im Be- reich der Anschlussstutzen und

Fig. 15

ein hydraulisches Schaltbild der Heizungsanlage mit Bau- einheit.

The invention is explained in more detail with reference to an embodiment shown in the drawing. Show it:

Fig. 1

in a perspective simplified representation of an inventive unit in installation position in the chassis of a compact heating system,

Fig. 2

a perspective view of the unit,

Fig. 3

a plan view of the unit,

Fig. 4

a view from the front of the unit,

Fig. 5

a view from the one installation position right side on the unit,

Fig. 6

a view from the left in the mounting position on the unit,

Fig. 7

the components forming a bypass and connecting the sub-assemblies in a perspective view,

Fig. 8

a view of the components according to Fig. 7 seen in installation position from the front,

Fig. 9

a section along the line AA in Fig. 8 .

Fig. 10

a perspective view of the pressure regulator,

Fig. 11

the pressure regulator according to Fig. 10 on average,

Fig. 12

the actuator of the pressure regulator in view,

Fig. 13

3 shows a longitudinal section through the line sections of the first substructure running parallel to one another,

Fig. 14

a longitudinal section through the first sub-assembly in the area of the connecting piece and

Fig. 15

a hydraulic circuit diagram of the heating system with construction unit.

The assembly 1 shown in the figures is arranged in the installed position in a chassis 2, which accommodates all components of the compact heating system and is attached to its rear wall 3 typically hanging on a wall or can be fixed floor-mounted or ceiling-mounted in providing a corresponding frame. The assembly 1 is arranged in the lower part of the chassis 2 and has four downgoing outgoing lines 4, 5, 6 and 7, which lie in a row parallel to the rear wall of the chassis 2 and to which the house-side water-carrying lines are connected. The upper part of the assembly 1 is, as usual in these devices, for receiving a burner and a primary heat exchanger arranged above it, these components are in Fig. 1 away. The assembly 1 has a right side in installation position upwards to the primary heat exchanger outgoing line 8, and a left side arranged, coming from the top of the primary heat exchanger line 9. Centrally centrally, a gas line 10 is guided, which is arranged in front of the unit 1 and in a likewise arranged in front of the unit 1 valve unit 11, which controls the gas supply to the burner.

The assembly 1 has a plate heat exchanger 12, which is arranged parallel to the rear wall 3 and is tabular. To the plate heat exchanger 12 includes in installation position right side from the front a first sub-assembly 13 and left side a second sub-assembly 14. The sub-assemblies 13 and 14 are essentially made of plastic injection-molded main bodies and arranged so that their mechanical connection substantially over the existing metal Plate heat exchanger 12 takes place.

The cable routing within the unit 1 and within the compact heating system results in detail Fig. 15 , The flowing back from the return of the space heating water passes through the right in the installed position line connection in the line 7 and thus in the first sub-assembly 13, which includes, inter alia, a centrifugal pump 15 and an air separator 16. The line 7 opens into the suction chamber of the centrifugal pump 15, to which the air separator 16 connects at the top. The discharge nozzle of the pump 15 is connected to the leading to the primary heat exchanger line 8. The pump housing and the remaining lines of the first sub-assembly 13 are formed by an injection-molded component. The centrifugal pump 15 has, as usual in such units, a flanged, in installation position from the front accessible electric motor 17, the terminal box 18 is disposed at the top of the motor housing.

In installation position from the front ( Fig. 4 Seen to the left of the pump 15 are two parallel to each other side by side in front of the plate heat exchanger 12 vertically arranged line sections 19 and 20 are provided, of which the left, arranged by the pump 15 at a distance line section 19 perpendicular to the line 6 of the unit 1 leads or this forms. About this line 6, the in-house service water pipe is connected. In this line section 9 is near the beginning of a line in Fig. 13 provided in the flow projecting obstruction 40 and provided in the flow direction at a distance behind a differential pressure sensor 41 which is provided in a direction perpendicular to the line section 19 connecting piece as removable sensor unit 21. This is a flow meter which works according to the vortex principle and detects the flow velocity of the process water flowing into the unit 1.

At the upper end of the line section 19 includes a flow diverting by 180 ° component 22, which connects the line section 19 with the right in the installed position next to it between pump 15 and line section 19 arranged right line section 20. The component 22 comprises a flow regulator, with which the flow rate is controlled, so that it is substantially independent of the line pressure. For this purpose, a pin-shaped actuating body 23 in the component 22 is arranged in alignment with the line section 20. The adjusting body has at its upper end a tool holder, here a square, with which it can be rotated about its longitudinal axis. The adjusting body 23 is mounted by means of a thread in the component 22, so that depending on the direction of rotation a flow-limiting provided with axis-parallel groove-like channels cone 24 more or less far into an elastic receptacle 25 (see Fig. 13 ) can be inserted, which is incorporated at the upper end of the right line section 20. Such flow regulators are state of the art, which is why their function is not described in detail here. The sealing of the actuating body 23 to the outside via a arranged on the actuating body 23 O-ring. The component 22 is fastened by means of screws to the line sections 19 and 20 laterally projecting projections. If a flow rate regulator is not to be provided, the component 22 can be replaced by a 180 ° tube bend without the injection molding component of the first substructure unit 13 adjoining it having to be changed.

The installation in the lower end of the line section 20 is connected via an arcuately guided in the sub-assembly 13 channel line section 42 with the lower right in the installed position of the plate heat exchanger 12. The overlying upper port of the plate heat exchanger 12 is connected via a likewise arcuate line section 43 with the suction chamber of the pump 15. These line sections 42 and 43 are arc-shaped, so that they can be formed by pivot cores from the back of the sub-assembly 13, while allowing a certain lateral offset.

The line section 42 has an opening at the bottom, which lines lead this line section 42 with a vertically downwardly leading channel 44, which formed widened down and forms a receptacle 45 for a valve 46, the valve body 47 via a from the outside between the Connection piece for the cold service water and the connection piece for the return of the heating water is arranged and accessible. This valve 46 has a sealing body 48 near the upper end of the valve body 47, which closes or opens the passage 44 depending on the position of the valve and then connects, via the space formed by the receptacle 45, to a line adjoining the bypass line at the rear within the sub-assembly 13 and thus to the return side of the heating circuit. By means of this valve 46, the hot water line can be connected to the heating circuit to fill the heating circuit or refill.

Alternatively, the sub-assembly 13 may be formed by correspondingly changing the take-up 45 and the channel 44 forming die core of the tool so that an opening between the channel 44 and the line section 42 is not formed. Then, the valve 46 is modified so that it forms only a connecting piece, which is connected depending on the position of the valve body 47 to the heating circuit or is closed off in contrast. This nozzle is then also used to fill or refill the heating circuit with water and is either fixed via a Disconnecteur, d. H. connected via a line with non-return valve located therein with the hot water side of the other, in installation position left sub-assembly 14 or via a hose-like line with a corresponding connection to the sub-assembly 14, which is also equipped there with a shut-off valve.

The right-hand conduit section 20 adjoins the lower right-hand connection of the plate heat exchanger 12 in the installed position so that the cold process water flows into the lower right-hand connection of the plate heat exchanger 12, flows through this to the lower left connection and there in a line part bent downwards through 90 ° opens, which forms at the end of the line 5 for emerging from the unit 1 warm hot water. This hot water is heated by heating water flowing countercurrently from the upper left port of the plate heat exchanger 12 to the upper right port. The upper right port is over a pipe section connected to the suction chamber of the pump 15 of the first sub-assembly 13.

The emerging from the primary heat exchanger hot heat transfer medium passes through the line 9 via a line section 26, which is part of the second unit 14 and seen in the installation position extends down and behind in an arc (s. Fig. 2 The receptacle 27 lies with its axis parallel to the plate heat exchanger 12 and at right angles askew to the impeller axis of the centrifugal pump 15. The recording is to the left in installation position from the left side a closure lid 29 accessible after removing the switch body can be pulled out of the receptacle side.

Center of the receptacle 27 opens the line section 26, depending on the switching position of the switching body of the switching valve 28, the coming from the primary heat exchanger line 9 connects with the line 4 for the flow of space heating or with the upper left in the installation position of the plate heat exchanger 12 for heating the service water , Accordingly, the conduit 4 close to the open end of the receptacle 27 substantially down to this, whereas the line section 26 adjacent thereto, substantially from above and front and the plate heat exchanger 12 leading line near the closed end of the receptacle 27 connects.

The switching valve 28 is controlled by an electric servomotor 30, which is above the plate heat exchanger 12, however, arranged in front of this and the axis of rotation lies in a vertical plane in which the longitudinal axis of the receptacle 27 is seconded. The switching valve 28 with the associated servomotor 30 is not detailed here described, it is exemplary in this respect EP 04 026 233 A1 referenced where such a valve is described in detail.

The second sub-assembly 14, whose basic structure is also formed of a plastic injection molded part, thus includes the switching valve 28 with the corresponding line connections and is firmly connected to the left in the installed position line connections of the plate heat exchanger 12, thus including the line 5. Mechanically, the first sub-assembly 13 and the second sub-assembly 14 substantially connected to each other via the plate heat exchanger 12, but also connect other compounds, such as the bottom plate of the chassis 2 and a bypass line, but which are connected so that they in the longitudinal direction of the plate heat exchanger 12 (in installation position in horizontal Direction) are movably guided in order to avoid the introduction of thermal stresses due to different material expansions.

To the line 4 for the flow of the space heating closes the back with a line section 31 to a bypass line 32, which connects the second sub-unit 14 with the first sub-unit 13 and laterally connected to the first sub-unit 13 in the region between plate heat exchanger 12 and the line sections 19 and 20 and thus forms a connection to the suction region of the pump 15. The line section 31 connects to a perpendicular thereto in the same plane extending line portion 33 which extends in addition to the plate heat exchanger 12 in alignment with it. This is angled in the installed position on the right side by 90 ° to the front and there goes into a line section 34 which is open toward the front and serves to receive a valve 35 in the form of an adjustable pressure relief valve. Near the front end of the line section 34, a line section 36 connects to the right, which extends parallel to the plate heat exchanger 12 in front of it. A back of this cantilevered support 37 comes to the bottom of the plate heat exchanger 12 to the plant. At this line section 36 in turn closes perpendicular to a fitting 38 receiving and thus open to the front line section, which is formed here, for example, as a filling valve for filling the heating system with water. The right end of the line section 36 is provided with an O-ring 39 and guided only in the direction transverse to the longitudinal axis of the line section 36 in the corresponding aligned receiving the first sub-assembly 14 so that a movement in the axial direction to compensate for tolerances and thermal expansion is possible.

LIST OF REFERENCE NUMBERS

1 -

unit

2 -

chassis

3 -

rear wall

4 -

Line for the heating flow

5 -

Head for the hot service water

6 -

Line for the cold process water

7

Line for the heating return

8th -

Line to the primary heat exchanger

9 -

Line from the primary heat exchanger

10 -

gas pipe

11 -

valve unit

12 -

Plate heat exchanger

13 -

first sub-assembly

14 -

second sub-assembly

15 -

rotary pump

16 -

air separator

17 -

electric motor

18 -

terminal box

19 -

Line section left vertical

20 -

Line section right vertical

21 -

Sensor unit Vortex

22 -

component

23 -

adjusting body

24 -

cone

25 -

elastic absorption

26 -

line section

27 -

Recording of the changeover valve

28 -

switching valve

29 -

cap

30 -

servomotor

31 -

line section

32 -

bypass line

33 -

line section

34 -

line section

35 -

fitting

36 -

line section

37 -

support

38 -

fitting

39

O-ring

40 -

obstruction

41 -

Differential Pressure Sensor

42 -

line section

43 -

line section

44 -

channel

45 -

admission

46 -

Valve

47 -

valve body

48 -

sealing body

Claims (14)

1. A part construction unit for a compact heating installation with two heating circuits, which comprises two connections which are on the rear side in the installation position, for connection to a vertical connection pair of a plate heat exchanger (12), and which comprises a centrifugal pump (15), characterised in that two conduit sections (19, 20) which are arranged next to one another and in an essentially vertical manner in the installation position are provided, which are conductingly connected by a component (22) which deflects the flow by about 180°, and that a throughput quantity meter (40, 41) is arranged in one of the conduit sections (19).
2. A part construction unit according to claim 1, characterised in that the throughout quantity meter (40, 41) is one which operates according to the vortex principle and which is arranged close to the beginning in the conduit section (19) on the on-flow side.
3. A part construction unit according to claim 2, characterised in that the conduit section (19) on the on-flow side, is arranged at a distance to the pump housing (15).
4. A part construction unit according to one of the preceding claims, characterised in that the conduit section (20) on the downstream side is arranged adjacent to the pump housing (15).
5. A part construction unit according to one of the preceding claims, characterised in that the obstruction (40) of the throughput quantity meter (40, 41) is designed as one piece with the conduit section (19).
6. A part construction unit according to one of the preceding claims, characterised in that the component (22) deflecting the flow comprises at least parts of a throughput quantity closed-loop controller (24, 25).
7. A part construction unit according to claim 6, characterised in that a control element (23) which may be actuated from the outside, for setting the throughput quantity, is arranged in the component (22) deflecting the flow.
8. A part construction unit according to one of the preceding claims, characterised in that a diaphragm-like component which comprises an elastic element (25), preferably an O-ring, is incorporated in the region of the housing division between the component (22) deflecting the flow and a component forming the conduit sections (19, 20).
9. A part construction unit according to one of the preceding claims, characterised in that the one conduit section (20) connects to a connection of the heat exchanger (12) and the other conduit section (19) connects to a connection (6) of the heating construction unit (1) or forms this.
10. A part construction unit according to one of the preceding claims, characterised in that the conduit sections (19, 20) which are arranged next to one another, in the installation position, are arranged roughly perpendicularly in front of the plate heat exchanger (12) and next to the centrifugal pump (15).
11. A part construction unit according to one of the preceding claims, characterised in that the part construction unit (13) comprises at least one, preferably two arched channels (42, 43) which connect to the plate heat exchanger (12).
12. A part construction unit according to claim 11, characterised in that one of the arched channels (43) connects to the suction side of the pump (15), and the other arched channel (42) connects on the vertical conduit section (20) which leads from the component (22) deflecting the flow, to the plate heat exchanger (12).
13. A part construction unit according to one of the preceding claims, characterised in that the vertical conduit section (20) leading from the component (22) deflecting the flow, to the plate heat exchanger (12), comprises an opening which is conductively connected to the suction side of the pump (15).
14. A part construction unit according to claim 13, characterised in that the opening runs into a valve chamber (45) which is preferably open at the bottom in the installation position and which is designed for receiving a valve body (47) or a shut-off body.

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