DK164305B - Rotatable heat exchanger - Google Patents

Abstract

The present invention relates to a rotary heat exchanger (10) for recovering heat or cold and/or moisture from gas flows. The heat exchanger comprises a casing (12) which incorporates gas-flow channels (16, 18). The heat exchange rotor (22) forms part of a withdrawable rotor unit (55), which also includes a frame (28) on which the rotor is journalled, a transverse wall (56) having an opening for accommodating the rotor, a rotor drive motor (40), and a cover plate (38) which is intended to cover an opening (36) in the casing (12) through which the rotor unit can be withdrawn. Arranged between the transverse wall (56) and the peripheral surface (62) of the rotor (22) is a radially directed peripheral seal (60), to which is connected within the area of the frame (28) an axial seal (82) and a diametrical seal (48) respectively.

Description

in

DK 164305 B

The present invention relates to a rotatable heat exchanger of the kind further described in the preamble of claim 1.

Swivel heat exchangers of this type are used to recover heat, cold and / or humidity from a first air stream and transfer the heat, cold and / or humidity recovered to a second air stream.

The first and second airflows may be e.g. ventilation air out and in of buildings, or other forms of airflow such as process airflows. The active part of the rotatable heat exchanger,. that is, the rotor is provided with axially extending ducts which allow passage of said air flows. The rotor may have different diameters, from about 500 mm to about 5000 mm or more, for the purpose of accommodating different air flows. the length of the rotor in its axial direction can be kept relatively short, usually approx. 200 mm, even when efficiency requirements are high.

The rotor is enclosed by a housing or rotor box having apertures which are directed axially to the air flow channels in the rotor. To prevent the two air streams from mixing in the rotor box, it is necessary to widen the rotor with effective seals, both across the diameter between two connected ducts and around the periphery of the rotor. For <20 this reason, previously known rotatable heat exchangers have been provided with axially extending peripheral seals located on both sides of the rotor. This location of peripheral seals allows the rotor to be removed sideways without the need to remove the peripheral seals, saving time winning maintenance work and the like, e.g. cleaning the air flow ducts of the rotor.

In order to achieve the highest possible efficiency for a rotatable heat exchanger, it is necessary that no air leak through the seals. All types of leaks are harmful in this regard. Air leaking to the same duct will not participate in the heat exchange process and will not have supplied or absorbed heat or moisture in the rotor. Leakage to the second duct results in an increase in the total air transport in the system, ie a reduction of the outflow air 2

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from the system or a reduction in the supply of fresh air to a ventilation system. Leakages of this kind can also result in the presence of harmful or unwanted air components in a wrong place, e.g. For example, such leakage may result in the transfer of gaseous solvents to a paint tent or other paint room.

Since the heat exchanger operates in accordance with the countercurrent principle, the airflow will enter a torque or torsion ("tilting") moment which tends to tilt the rotor relative to the rotor box and its seal.

This torque increases very strongly with increasing rotor diameter. Tilting of the rotor relative to the rotor box tends to cause leaks, especially in the axially directed peripheral seals. The seals that extend diametrically are not normally affected to the same degree as they are positioned close to the plane of symmetry for the tilting motion. The efficiency of the heat exchange seals against leakage is impaired by each millimeter of rotor tilt.

In order to avoid tilting the rotor and thus the risk of leakage, especially in large diameter rotors, it is necessary to install very stable rotor shaft pins, which of course greatly increase the cost.

Despite this, it is difficult to prevent the rotor from tilting in the long run, as just minor wear of the rotor shaft pins will result in a few millimeters of tilt of the rotor periphery.

Another way to prevent leakage is to use axially extending seals which are resiliently actuated to force against the peripheral surface of the rotor. However, the powerful adjoining pressure exerted by these seals provides greater frictional resistance and increases the energy cost of using the heat exchanger. Furthermore, such high-precision seals are subject to great wear, and the seals are therefore quickly worn down, with significant problems with leaks.

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Leakage can also occur as a result of rotor throw or of rotor disturbances, the rotor often being made of a relatively soft material such as thin aluminum sheet. The size of these disturbances or deformations is usually in the range of 1-3 mm.

In view of the aforementioned disadvantages of prior art rotatable heat exchangers, the object of the present invention is to provide a heat exchanger which will be well sealed around its periphery independent of rotor tilt or rotor deformation which may occur. The object is furthermore to provide a rotatable heat exchanger, the sera 10 is simply designed, has low manufacturing cost and can be quickly and easily dismantled and assembled for repair and maintenance.

These objects are achieved by a rotatable heat exchanger constructed in accordance with the invention and having the characteristic features as mentioned in the characterizing part of claim 1.

15 By adjusting the rotor propellants to a part that can be retracted together with the rotor, it is possible to insert and remove the rotor with minimal stopping or operating disturbance time.

The invention is further described with reference to a non-limiting embodiment thereof and with reference to the enclosed, partially schematic, drawing. The drawing shows:

FIG. 1 is a perspective view of a prior art heat exchanger;

FIG. 2 is a longitudinal sectional view of the heat exchanger shown in FIG. 1 and illustrates leakage current,

FIG. 3 is a partially cut-away axial view of the commodity exchanger shown in FIG. 1 and illustrates leakage current,

FIG. 4 is a perspective view of a heat exchanger constructed in accordance with the present invention illustrating a rotor assembly in partially retracted position, side plates or cover plates removed for clarity; FIG. 5 is a longitudinal sectional view of a heat exchanger shown in FIG. 4 and illu- 4

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contradict the design principle of the peripheral seals,

FIG. 6 shows a part of the rotor fitted with a peripheral seal and FIG. 7a-j are examples of different variants of peripheral seals according to the invention.

FIG. 1-3 illustrate a prior art heat exchanger 10 arranged in a box 22 which comprises the opening 14 with space for first and second air flow ducts 16, 18. supply air and outgoing · air flows in a ventilation system. The ducts are connected to the box 12 in the usual way, that is, by means of designated connection flanges or pipe nozzle 20. Located within the box is a heat exchanger rotor 22 which has a closed hub portion 24 surrounded on the outside by flow openings. The rotor shaft, shown only at the shaft center axis 26, is coupled or attached to a frame structure 28. The frame structure 28 of the shown heat exchanger is known from applicant's Swedish patent application SE-A-8200 696-6 and consists of two beams, ribbons or rails. 30, which comprises the rotor shaft pins or rotor connection means and which are solidly coupled at a crosspiece 32. The frame 28 can be inserted or retracted from the box of the rails 34 mounted on the inside of the box between the connection openings 14 of the two air flow ducts. The rotor and frame pass through an opening 36 in one side wall of the box, which is covered by a side plate 38 or the like, which can be attached to the frame 28. Also mounted in the box 12 is a drive motor 40, such as a belt-drawn motor which is coupled. to a distributor box 44 by means of an electric cable 42. The channel opening towards the rotor is sealed by axially extending peripheral seals 46 and by diametrical seals 48 arranged on the rails 34 or on the beams or the like 30.

When the heat exchanger is in operation, a first flow of air passes through the duct 16 and delivers its heat to the rotor material. As the rotor rotates 30 along the second conduit 18, the rotor supplies the heat stored therein to the second air stream. Since openings 50 will occur, at least in time, between the rotor 22 and primarily the perfective seals 46, as mentioned above, leakage air flows 52 will pass on one side of the tube.

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the tower through the opening 54 which goes around the rotor in the box. This leakage air will pass through the rotor and either return to the same duct from which it leaks out (cf. in particular Fig. 2) or pass into the second air flow duct, as shown in fig. 3. Both of these cases have a detrimental effect, 5 as mentioned earlier.

The harmful conditions and leakage currents described with reference to FIG. 1-3 are not limited to the heat exchange construction shown, but are common in all heat exchangers using axially extending peripheral seals. For example, the same destructive conditions 10 will be seen when the rotor is suspended directly on the heat exchanger box 12 or on a frame completely surrounding the rotor 12, in the form of an inner box on which both diametrical seals and axially extending peripheral seals are mounted.

FIG. 4 shows a construction according to the invention in which leakage in the peripheral seals is eliminated. This construction, generally shown at 55, comprises a transverse wall 56 provided with an opening 58 to accommodate the rotor 22 on a retractable frame 28 and a peripheral seal 60 disposed between the peripheral surface 62 of the rotor and the transverse wall. 56. Examples of various variants of seals 60 are shown below with reference to Figures 6 and 7. The transverse wall 56 abuts the floor 64 and the roof 66 of the box 12 between intermediate guide and sealing rails 68. the rails 68 have the transverse wall 56 at least one perpendicular flange plate 70, 72 which has at its free end a perpendicularly curved bracing flange 74. Similarly, the outer and inner end edges of the transverse wall 56 are each provided with at least one flange plate 70, 72 and a stiffening flange 74 for abutting sealing against the rear wall 76 of the box 12 and the inner surface of the side cover plate 38. To increase the sealing effect, sc For example, at least one flange of the back wall 76 and the side cover plate 38 and / or said 30 may be covered with suitable material such as rubber, preferably foam rubber.

The transverse wall 58 also carries a housing 78 for the rotor drive motor 44.

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The drive from the motor 44 to the rotor is performed over a drive belt 80 or equivalent drive means which is coupled to the peripheral surface 62 of the rotor. Greeting 78 has a sealed passageway (not shown) through which cable 42 passes to transfer box 44. According to the first variant, side cover plate 38 is fixedly mounted on frame 28, in case incoming power supply cable for the drive motor is pulled through cover plate 38 and connected to an electrical outlet by means of a cable shoe or plug. This allows a simple retraction of the rotor from the heat exchanger box for repair or purification by simply disconnecting power to the sewing cable and then retracting the rotor unit 55 consisting of the rotor 22, frame 28, transverse wall 56 and drive means 40 together with the connection box 44. This results in much shorter disassembly and shutdown times, especially when a spare part is available for immediate installation. The method used in this way is much faster than the method used in the prior art, where the cover plate, drive motor and clutch box must each be removed separately before the rotor can be withdrawn from the heat exchanger box.

In the embodiment shown in FIG. 4, two diametrical seals 48 are arranged on the longitudinal beams or rails 30 of the frame 28, at least 20 on one side. On the periphery of the rotor, the diametrical seals 48 are integrally blended with axially extending peripheral seals 82 extending to the transverse wall 56. The peripheral seals 82 show openings for passage of the drive belt 80 on the drive belt side of the transverse wall. This allows the drive belt and peripheral sealing arrangement to be shaped so as to obtain the least possible gap, that is, by operating the motor with a V-belt. Alternatively, the drive belt may be placed in a groove in the drive rotor to align with the peripheral rotor surface 62. It is possible to reduce the area of leak openings upon passage of the drive belt to a maximum of one or two square 30 millimeters. Instead of placing diametrical seals on the beams or rails 30, these seals can be placed on the guide rails. In that case, the perfective seal 82 is preferably lowered in plane with the frame 28.

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FIG. 5 shows a longitudinal sectional view of a water exchanger constructed in accordance with the invention. The heat exchanger box for this embodiment has no internal space where transfer from one duct to the other can take place. Any small leakage current 84 which may manifest on the pervious seal 80 passes directly from one channel side to the other. Even relatively noticeable tilting or deformation of the rotor 22 will only result in negligible changes in the radius of the seal, these changes being within the normal elastic support elasticity of the seal. The magnitude of the change in radius can be calculated geometrically. When the rotor is tilted through an angle or, the maximum change in radius is the result of this (l-cosce) r. A corresponding maximum change of an axially directed perfiferous seal is its £ & * r. When at = 1 °, 0.0002 * r and 0.0175 * r, respectively, are obtained, while the corresponding values for 0c = 5 ° are 0.0024 * r and 0.0878 * r, respectively. , that the change in radially disposed peripheral seals caused by tilting of the rotor is negligible in comparison with axially directed peripheral seals.

Leakage as a result of irregularities in the rotor position is also less in the radial direction of the rotor than in the axial direction. Due to the short length and large diameter of the rotor, deformations will occur much more easily in the axial direction than in the radial direction.

FIG. 6 shows in detail the arrangement of a seal 60 between the transverse wall 56 and the peripheral overlap 62 of the rotor. The seal shown in FIG. 6 corresponds to the variant shown in FIG. 7a and consists of a brush seal 60a secured to the cross wall 56 by means of fasteners 86.

FIG. 7 comprises a plurality of schematic cross-sections of the transverse wall, 56, its connecting portion to the guide and the sealing rail 68 and the peripheral seal against the peripheral overlap 62 of the rotor 22. In this case, the variants shown in FIG. 7a-7e, on the one hand, a protruding flange 70 provided with a rearwardly bent stiffening flange 74. The variants shown in FIG. 7f-7j, is similar to the above, assuming that these variants are also provided with a substantially L-shaped edge shape.

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clamping 88 having a long connecting flange 90, a flange plate 72 and a stiffening flange 74. The long connecting flange is secured to the transverse wall 56 in a suitably known manner, that is, screwed, pop-riveted, or spot welded. The edge reinforcement 88 and guide and seal rail 68 are arranged to prevent air from leaking. The use of edge reinforcement 88 results in symmetrical control of transverse wall 56 in guide and seal rails 68.

Figures 7a-e and 7f-j show corresponding variants of peripheral seals on the transverse wall 56 without or with edge reinforcement 88. Va-10 variants 7a and 7f comprise a peripheral seal 60 having a brush seal member 60a and fasteners 86. The variants shown in Figs. FIG.

7b and 7g comprise a seal having the shape of an elastic edge, i.e. a rubber edge 60b and having an upwardly bent side edge adjacent to the peripheral overlap 62. This seal may consist of a double bend, in which case the free end is bent in respective directions. In the case of a simple seal, the upwardly bending side will face the airflow, so that the air pressure will push the rubber edge against the peripheral overflow of the rotor, thereby enhancing the sealing effect. In the case of a simple seal, a seal 60b must be directed 20 in different directions in the two channels 16, 18. FIG. 7c and 7h show a felt seal or a plurality of edge seal 60c having fasteners 86. FIG. 7d and 7i show a radially extending maze seal 60d which also includes a portion secured to the peripheral surface 62 of the rotor. As mentioned earlier, tilting of the rotor results in a marked deviation in the axial direction, but only a slight deviation in the radial direction. Therefore, the maze seal 60d must be sufficiently flexible to accommodate such axial deviation.

FIG. 7e and 7j show a seal 60e provided with a brush seal element corresponding to the seal 60a of FIG. 7a and 7f, but with a different shaped fastener 86 '. The fastening element 86 'comprises a flange or sleeve 96 which projects axially out from the transverse wall 56 and is preferably made of elastic material such as rubber. The flange 96 is attached to a support member 98 which supports 9

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then real sealing. Sealing elements 60b, 60c and 60d can also be used. The seal 60e provides a given degree of resilient adjustability for wear in the flange or cuff 96, and since it can be mounted and easily dismantled in the axial direction, it is an advantage in maintenance.

The heat exchanger frame 28 may have a shape different from the embodiment shown. For example, the frame may also comprise reinforcements so perpendicular to the beams or rails 30 coupled to transverse wall 56 and guided to guide and seal rails 68. According to another variant, the frame may consist of a box or housing. soti completely encloses the rotor. This housing has a stationary transverse wall 56 suitable for the inside thereof and can be replaced in and out of an outer heat exchanger box 12.

The embodiment shown consists of a rotor which can have a horizontal shaft and 15 which can be replaced linearly in a horizontal direction. This also means that the rotor can be provided with vertically extending air ducts and a vertical shaft and arranged for retraction and insertion in a horizontal direction. Although other orientation of the rotor shaft and direction of retraction of the rotor is also achievable in principle, but it results in practical problems and should therefore be avoided.

In addition to electrical connection, the distributor box 44 may also contain other types of electrical components, e.g. a rotor speed control unit, automatically activated or externally activated emergency stop device or electrical switches and parts of various instruments for monitoring the function of the heat exchanger.

Such electrical components are inherently known technology and the novelty represented by such components lies in the location of said components on a heat exchanger part which can be withdrawn from the heat exchanger box together with the rotor.

According to another embodiment of the invention, the side cover plate 38 is 10

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prepared from the frame 28 and mounted on the box 12 with hinges (not shown).

This allows an opening of the box to be inspected, e.g. while the heat exchanger is working, without having to remove the entire rotor assembly.

In the case of this embodiment, the electrical cable is not drawn through the cover plate and can advantageously be connected to the electrical socket on the inside of the box or alternatively connected to an electric socket on the rotor unit, preferably to the distributor box.

Alternatively, the distributor box may be placed on a stationary portion of the box 12, e.g. on an outer assault of this one. In that case, the electrical cable 42 is pulled through the cover plate 38 and connected to the distributor box by means of a plug or cable shoe.

Extra power cables for power, e.g. measuring instruments and monitoring and operating instruments, can be connected in a similar manner by means of plugs or the like, which enable the cables to be easily disconnected.

Instead of a drive belt running around the rotor, the rotor can be driven e.g. by friction drive with the peripheral surface 62 of the rotor in a known manner. This eliminates the need for the belt groove, thereby removing significant leakage risk at the peripheral seal 82.

As will be seen from the aforementioned, the rotor 22, the frame 28, the transverse wall 56, the radially disposed peripheral seal 60, the side cover plate 38 (when inserted), the drive motor 40 and (when inserted) the distributor box 44 together form a rotor unit 55 which can be retracted and inserted into the heat exchanger box 12 in the form of a single package. When inserted into box 12, the rotor unit is sealed against the box walls in the flow direction and between the channels by guide and seal rails 68 and the diametrical seal disposed in connection with the beams or rails 30 and / or corresponding guide rails 34.

It will be appreciated that the invention is not limited to the embodiment shown and described therein and that the essential features of the invention may be combined in any desirable manner according to the scope of the following claims.

Claims (8)

A rotatable heat exchanger for recovering heat or cold and / or humidity from one of two air streams which are passed parallel to each other through each duct (16, 18) connected to openings (14) in a box (12) which includes a rotor (22) having axially 5 openings for air flow, the rotor being suspended on a rear arm (28) which can be retracted through a side opening (36) in said box (12), seals (48, 60, 82) which is arranged to counteract undesirable leakage around the cm rotor, characterized in that a transverse wall (56) having a circular aperture (58) for the rotor (22) and a support for supporting the rotor is mounted against sealing-related walls (64, 66) of said box which are parallel to the direction of movement of the frame (28) via guide and sealing rails (68), the respective edges of the transverse wall (56) are bent at right angles to form guide and sealing flanges (70, 72) which are parallel-15 slightly relative to and supporting against the ribs of said rails (68), that both sides of the transverse wall are arranged to support against the closed rear side (76) and a plate (38) thus covers said side opening (36) in the box and that within the circular aperture (58) is provided a peripheral seal (60) which is preferably supported by the transverse wall and which connects within the region of the frame (28) an axial seal (82) and a diametrical seal (48). respectively. A heat exchanger according to claim 1, characterized in that the drive motor (40) is mounted on the transverse wall (56) preferably in a housing (78) constructed on said transverse wall. A heat exchanger according to claim 1, characterized in that the plate (38) covering the box opening (36) is fixed to the frame (28) and / or the transverse wall (56), in that the plate is designed to seal support against it. outer edge of the transverse wall (56), and by allowing the plate (38) to be retracted together with the frame (28) and the transverse wall (56). DK 164305 B A heat exchanger according to any one of claims 1-3, characterized in that the electric power cable (42) coupled to the drive motor (40) can be removably coupled to a stationary electrical contact (not shown) and / or by the distributor box (44). the drive motor 5 (40) is arranged in such a way that it can be retracted together with the rotor (22) and the frame (28), preferably mounted on the transverse wall (56). A heat exchanger according to one or more of the preceding claims, characterized in that the transverse wall (56) has at least 10 a stiffening flange (74) extending from the free end of the plate flange (70, 72) supporting against said rails in a sealing interaction with these. A heat exchanger according to claim 1, characterized in that the peripheral seals have through openings to provide space 15 for the rotor drive belt (80). A heat exchanger according to one or more of claims 1-6, characterized in that the radially directed peripheral seal (60) between the transverse wall (56) and the peripheral surface of the rotor consists of a brush seal (60a), a simple or the double fold 20 elastic edge, preferably a rubber edge (60b) having upward or beyond folded side edges supporting the peripheral overlap (62), or a multiple fold edge seal (60c) and by said sealing element (16a, 16b, 16c) being connected directly to the transverse wall (56) or between the intermediate separate connecting element (86). A heat exchanger according to one of claims 1-6, characterized in that the radially directed peripheral seal (60) consists of a maze seal, a part of the maze seal being arranged on the transverse wall (56) while another part of the maze seal is arranged on the peripheral surface (62) of the rotor and in that the maze seal exhibits sealing surfaces having a radial extension (60d) or sealing surface (60e) extending parallel to the peripheral surface (62) of the rotor (22).