FI91674C - Rotary 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a cover plate (38) which is intended to cover an opening (36) in the casing (12) through which the rotor unit can be withdrawn.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

• · 4 · · ^ ·

Rotary heat exchanger 91674

The present invention relates to a rotary heat exchanger of the type 5 set out in the preamble of claim 1.

This type of rotary heat exchanger has been used to recover heat, cool and / or moisture from the first gas flow and to transfer the recovered heat, cool and / or moisture to the second gas flow. The first and second gas streams may be, for example, air conditioning air leaving the building and entering, or gas streams in some other form, such as process gas streams. The active part of the rotary heat exchanger, i.e. rotor, is provided with axial channels which allow the passage of said gas flows. The rotor can have different diameters, from about 500 mm to about 5000 mm to accommodate 20 or more different gas flows.

The length of the rotor in the axial direction can be kept relatively short, usually about 200 mm, even in cases where the power requirements are high.

25 The rotor is surrounded by a housing or rotor housing in which openings are formed which point axially ** towards the gas flow channels of the rotor. In order to prevent the two gases from mixing with each other in the rotor housing, it is necessary to provide the rotor with effective seals, 30 as well as across the diameter between the two connecting channels and around the circumference of the rotor. To this end, axial circumferential seals are provided in the rotary heat exchangers according to the prior art, which are arranged on both sides of the rotor. This arrangement of the circumferential seals allows the rotors to be removed laterally without having to remove the circumferential seals, which saves time when performing maintenance work, e.g. cleaning the rotor gas flow channels.

2 91674 • · «· ·· ·· · ·

In order to achieve the best possible performance of the rotary heat exchanger, it is essential that no air leaks past the seals. All leakage types 5 are harmful in this regard. Air leaking into the same duct has not taken part in the heat exchange process and has not transferred or absorbed heat or moisture in the rotor. Leakage to the second duct leads to a reduction in the total gas flow in the system, e.g. a reduction in the exhaust air leaving the system or a reduction in the supply of fresh air to the air conditioning system. Such a leak can also lead to the presence of harmful or undesired gas components in the wrong place, e.g. such a leak can lead to the transfer of gaseous solvents to the spray canopy or other painting space.

Because the heat exchanger operates on the countercurrent principle / the gas flows generate a heeling moment (tilt) 20 which tends to tilt the rotor with respect to the rotor housing and its seals. This torque increases very rapidly as the rotor diameter increases. Tilting the rotor relative to the rotor housing creates a leakage opening and, in particular, in the circumferential seals in the axial direction 25. Seals located in the diameter direction are usually not exposed to the same extent because they are located close to the plane of symmetry of the tilting motion. The power of the heat exchanger seals against leakage 30 deteriorates considerably with each millimeter of rotor tilt.

In order to avoid the tilting of the rotor and the consequent risk of leakage, e.g. in the case of large diameter rotors 35, it has been necessary to provide very stable rotor bearings, which of course greatly increases the cost. Nevertheless, it is difficult to prevent the rotor from tilting over a long period of time, as only a small amount of wear on the rotor bearings quickly results in a tilt of the rotor circumference of a few millimeters. .

5

Another method of preventing leakage is to use axially extending circumferential seals which are arranged elastically in strong contact with the circumferential surface of the rotor. However, the strong contact pressure caused by these seals 10 generates high frictional resistance forces and increases the energy costs of operating the heat exchanger. In addition, such highly prestressed seals are subject to a lot of wear and the seals wear out rapidly as a result, resulting in leakage problems.

Leakage can also occur due to rotation of the rotor or distortion of the rotor, as the rotor is often constructed of a relatively soft material, such as a thin sheet of aluminum. The extent of these distortions or deformations is usually of the order of about 1-3 mm.

In view of the above-mentioned drawbacks of the prior art rotor heat exchangers 25, it is an object of the present invention to provide a heat exchanger which is well sealed around its circumference, regardless of any possible rotor tilt or rotor deformation. It is a further object to provide a rotary heat exchanger which has a simple construction, low manufacturing costs and can be quickly and easily disassembled and reassembled for repair and maintenance.

% 35 These objects are achieved by a rotary heat exchanger having the structure according to the invention and the characteristic features set forth in the characterizing part of claim 1.

«·· · ·· ♦ ♦ ♦ · 4 91674

By fitting the rotor actuators to a part which can be removed together with the rotor, it is possible to fit and remove the rotor in such a way that the downtime is as short as possible.

The invention will now be described in more detail with reference to, for example, a non-limiting exemplary embodiment thereof, with reference to the accompanying, partly schematic drawings, in which Fig. flow, Fig. 3 is a partially sectioned axial view 20 of the heat exchanger shown in Fig. 1 illustrating a leakage flow; Fig. 4 is a perspective view of a heat exchanger constructed in accordance with the present invention. longitudinal section of the air exchanger 30 illustrating the structural principle of the circumferential seals, Fig. 6 illustrates a part of the rotor to which the circumferential seal is fitted, and Figures 7a-j illustrate the circumferential components of the invention. various examples of transformations.

Il s 91674 • I · · »· ····· Μ ··· · · ·

Figures 1-3 illustrate a previously known lamp exchanger 10 housed in a housing 22 having openings 14 for accommodating a first and a second gas flow passage 16, 18. These gas flows can e.g.

5 includes core air and exhaust air flows in the air conditioning system. The ducts are connected to the housing 12 in a normal manner, e.g. by means of the connecting flanges or pipe projections 20 shown. Inside the housing is arranged a heat exchanger rotor 22 with a closed hub part 24, which is surrounded on the outside by flow-through openings. The rotor shaft, shown exclusively on the central shaft 26 of the shaft, is mounted or firmly attached to the frame structure 28. The frame structure 28 of the described heat exchanger is known from the Swedish patent application SE-A-8200696-6 of the applicant 15 and comprises two rods, strips or beams 30 with rotor shaft bearings or rotor mounting means and rigidly connected together by a transverse body 32. The frame 28 can be pushed into the housing 20 or pulled out of the housing 12 by rails 34 located inside the housing between the connection openings 14 of the two gas flow channels. The rotor and the frame pass through an opening 36 in one of the side walls of the housing, and this opening is covered by a side plate 25 38 or the like which can be fixed to the frame !! 28. The drive 12 is also provided with a drive motor 40, e.g. a belt drive motor, which is connected to the junction box 44 by means of an electrical line 42. The channel openings in the rotor are sealed with circumferential seals 46 in the axial direction 30 and seals 48 at the diameter, which are arranged on rails 34 or rods or the like 30.

When the heat exchanger is running, the first gas flow 35 passes through the duct 16 and transfers heat to the rotor material. When the rotor rotates at the second duct 18, the rotor releases the heat stored in it to the second gas flow. Since gaps 50 are formed at least over time between the rotor 22 and primarily the circumferential seals 46, as mentioned above, leakage gas flows 52 flow on one side of the rotor inside the housing through the space 54 surrounding the rotor. This leaking gas passes the rotor and either returns to the same duct from which it leaked (see in particular Figure 2), or it enters another gas flow duct, as shown in Figure 3. Both events have detrimental effects, as mentioned above.

The detrimental conditions and leakage currents shown with reference to Figures 1-3 are not limited to the heat exchanger design shown, but are common to all heat exchangers with axially located circumferential seals. For example, the same detrimental conditions are encountered in cases where the rotor is mounted directly in the heat exchanger housing 12 or in a frame that completely surrounds the rotor 20 as an inner housing into which both the diameter seals and the axial circumferential seals are fitted.

Figure 4 shows a structure according to the invention by means of which leakage at circumferential seals is eliminated.

This structure, generally described at 55, includes a transverse wall 56 having an opening 58 for accommodating the rotor 22 in the retractable frame 28, and a circumferential seal 60 disposed 30 between the circumferential surface 62 and the transverse wall 56 of the rotor. Examples of various modifications of the seal 60 are shown below with reference to Figures 6 and 7. The transverse wall 56 rests against the floor 64 and the roof 66 of the housing 12 via guide and sealing rails 35 68. To ensure forced support on the rails 68, the transverse wall 56 has at least one angled flange connection plate 70, 72,

II

7 91674 • · · · · ·> »· · · · · Having at its free end an angled stiffening flange 74. Respectively, the outer and inner end edges of the transverse wall 56 are each provided with at least one flange connecting plate 70, 72 and a stiffening flange 5 74 In order to improve the sealing effect thus obtained, the rear wall 76 and the side cover plate 38 and / or said at least one flange can be covered with a suitable material, such as rubber, preferably foam rubber.

The transverse wall 58 has a myds housing 78 for the rotor drive motor 44. The rotation of the rotor by the motor 44 is provided by a drive belt 80 or other similar drive member in communication with the circumferential surface of the rotor 62. The housing 78 has a sealed lead-through (not visible) through which the wire 42 passes into the junction box 44. According to a first modification, the side cover plate 38 is attached to the frame 28, 20 in which case the incoming power supply This allows the rotor to be comprehensively withdrawn from the heat exchanger housing for repair or cleaning simply by disconnecting the power supply line and pulling out the rotor unit 55 which encloses the rotor 22, the frame 28, the transverse wall 56 and the actuators 40 together with the junction box 44. As a result, unloading and stopping times are much shorter, especially when the spare unit is used for a non-selective installation. The procedure thus done is thus much faster than the procedures used according to the prior art, in which case the cover plate, the drive motor and the switch box must each be removed one by one before the rotor can be pulled out of the housing of the heat exchanger.

ψ · ·· ti ·· ···· ····· t · 8 91674

In the case of the embodiment shown in Figure 4, two diameter seals 48 are arranged on at least one side of the longitudinal bars or beams 30 of the frame 28. At the diameter 5, the seals 48 are fixedly connected to the circumferential seals 82 in the axial direction on the rotor circumference, which extend to the transverse wall 56. The circumferential seals 82 have openings for the passage of the traction belt 80 on the side of the transverse wall traction belt 10. This makes it possible to shape the drive belt and circumferential seal system to obtain the smallest possible gap, e.g. by using a motor with a downward V-shaped belt. Alternatively, the drive belt can be fitted in the groove of the drive rotor 15 so that it is in the plane of the circumferential surface 62 of the rotor. It is possible to reduce the area of the leakage slot at the drive-through of the drive belt to a maximum of 1 or 2 square millimeters.

Instead of placing the seals 20 at the diameter on the rods or beams 30, these seals can be placed on the guide rails. In this case, the circumferential seals 82 are preferably embedded in the plane of the frame 28.

Figure 5 is a cross-sectional view of a heat exchanger constructed in accordance with the invention. There is no interior space in the housing of the heat exchanger of this embodiment where flow could take place from one duct to another.

Any small leakage flow 84 that may occur at the circumferential seal 80 passes directly from one side of the channel to the other. Also, a relatively significant tilt or deformation of the rotor 22 results in only insignificant changes in radius at the seal, and these changes are within the normal elastic contact flexibility of the seal 35. The magnitude of the change in this radius can be calculated geometrically. When the rotor tilts at an angle α, the resulting li, 91674 m Λ · * ·· * • β · ♦ · · * *, the maximum change in precipitation is (1-cos a) r. The corresponding maximum change for the axial circumferential seal is sin a x r. When a = 1 °, the corresponding values are 0.0002 x r and 0.0175 x r, and with a = 5 ° 5, the corresponding values are 0.0024 x r and 0.0878 x r. It can be seen from this that the changes in the radially arranged circumferential seals due to the inclination of the rotor are insignificant compared to the axial seals located in the axial direction.

10

Leakage due to rotor position irregularities is also smaller in the rain direction of the rotor than in its axial direction. Due to the small length and large diameter of the rotor, deformations occur more easily in the axial direction than in the rainy direction.

Figure 6 shows in detail the arrangement of the seal 60 between the transverse walls 56 and the circumferential surface 62 of the rotor. The gasket 20 shown in Fig. 6 corresponds to the modification shown in Fig. 9a, and comprises a brush gasket 60a attached to the transverse wall 56 by the fixing member 86.

Fig. 7 comprises a series of schematic cross-sectional views 25 of a transverse wall 56, its connection portion to the guide and sealing rail 68, and a circumferential seal abutting the circumferential surface 62 of the rotor 22. In this manner with the stiffening flange 74. The modifications shown in Figures 7f to 7j correspond to the above, except that these modifications are also provided with a substantially L-shaped edge reinforcement 88 having a long connecting flange 90, a flange-35 connecting plate 72 and a stiffening flange 74. The long connecting flange is attached to the transverse wall 56 in any suitable known manner, e.g. by screwing, pop rivets or spot welding. An edge reinforcement 88 and a guide and • »·« ·· ·· 10 91 674 sealing rail 68 are provided to prevent gas leakage. The use of the edge reinforcement 88 provides symmetrical control of the transverse wall 56 in the guide and sealing rails 68.

5

Figures 7a-e and 7f-j illustrate corresponding modifications of the circumferential seals in the transverse wall 56 without or with the edge reinforcement 88. Modifications 9a and 9f have a circumferential seal 60 with a brush-like sealing portion 10 60a and fastening members 86. The modifications shown in Figures 7b and 7g have a seal in the shape of an elastic lip, e.g. a rubber lip 60b, with an upwardly folded side edge 62 supported against the circumference This seal may have a double fold, in which case the free end is folded in corresponding directions. In the case of a simple seal, the upwardly folded side is at the direction of the gas flow so that the pressure of the gas presses against the rubber lip against the circumferential surface of the rotor and thus increases the sealing power. In the case of a single seal, the seal 60b is oriented in different directions in the two channels 16, 18. Figures 7c and 7h show a felt seal or a multi-fold lip seal 60c with fastening members 86. Figures 9d and 9i show a radial labyrinth seal 60 is attached to the circumferential surface of the rotor 62. As mentioned above, the tilting of the rotor results in a significant deviation in the axial direction, but only an insignificant deviation in the radial direction. As a result, the labyrinth-30 seal 60d must be flexible enough to accommodate such axial aberrations.

Figures 7e and j show a seal 60e provided with a brush seal portion corresponding to the seal 60a of Figures 7a and 7f, but with a differently shaped mounting portion 86 '. The mounting portion 86 'comprises a flange or turn 96 projecting axially 11 * * · 11 91674 outwardly from the transverse wall 56 and preferably made of a resilient material such as rubber. The flange 96 is attached to a holding part 98 which supports the actual seal. The sealing parts 60b, 60c and 60d can also be used. The seal 60e provides a certain degree of elastic wear to the flange or turn 96, and because it can be conveniently fitted and disassembled in the axial direction, it greatly facilitates maintenance.

The heat exchanger frame 28 may have a different shape than the illustrated embodiment. For example, the frame may also have supports perpendicular to the rods or beams 30 connected to the transverse wall 56 and guided by a guide and sealing rail 68. Alternatively, the frame may have a housing or housing that completely surrounds the rotor.

This housing has a fixed transverse wall 56 which is fitted inside it and is movable inside and out of the housing 12 of the outer heat exchanger 20.

The embodiment shown has a rotor with a horizontal shaft which can be moved in a straight line in a horizontal direction. However, it is clear that the rotor 25 can be provided with the most vertical: gas ducts and a vertical shaft and can be arranged to be pulled and pushed in horizontally. Other directions of the rotor shaft and the direction in which the rotor can be retracted are also in principle manageable, but they cause operational problems and should therefore be avoided.

In addition to the electrical connections, the junction box 44 may also include other types of electronic components, such as a rotor speed control device, automatically operated or externally actuated emergency stop members or electronic switches, as well as parts of various instrument actuators.

I · ······ 12 91674 Such electrical components are known per se in the art, and the novelty of such components is their placement in the part of the heat exchanger which can be pulled out of the heat exchanger housing together with the rotor.

According to another embodiment of the invention, the side cover plate 38 is separate from the frame 28 and is arranged in the housing 10 12, e.g. with hinges (not shown). This makes it possible to open the housing opening for inspection, eg when the heat exchanger is running, without having to remove the entire rotor unit. In the case of this embodiment, the power line is not inserted through the cover plate 15 and can advantageously be connected to an electrical socket arranged inside the housing, tax alternatively connected to an electrical socket in the rotor unit, preferably to a junction box.

Alternatively, the junction box may be located in a stationary part of the housing 12, e.g. on its outer surface. In this case, the power line 42 is passed through the cover plate 38 and connected to the junction box with a plug or terminal block.

25

Other electrical cables for supplying power, e.g. to measuring instruments and monitoring and actuators, can be connected in a similar manner by means of plugs or the like, which enable the cables 30 to be disconnected quickly.

Instead of a drive belt running around the rotor, the rotor can be driven, for example, by means of a friction pull against the circumferential surface 62 of the rotor in a known manner. This 35 eliminates the need for a belt groove and thus the consequent risk of leakage at the circumferential seal 82.

ΐ3 91674 • · β β · * · * · "

As can be seen from the above, the rotor 22, the frame 28, the transverse wall 56, the radial circumferential seal 60, the side cover plate 38 (fitted), the drive motor 40 and the junction box 44 when fitted therein together form a rotor unit 55 which can be withdrawn from the housing 55 in one package. When inserted into the housing 12, the rotor unit is sealed against the walls of the housing in the flow direction and from the channel space 10 by means of diameter seals arranged in connection with the guide and sealing rails 68 and the rods or beams 30 and / or the corresponding guide rails 34.

It is clear that the invention is not limited to the described and described embodiments thereof and that the significant features of the invention can be combined in any desired way within the scope of the following claims.

Claims (8)

1. Rotary heat exchanger (10) for heat recovery and resp. cooling and / or moisture from one of two gas streams, which are intended to be forcibly controlled, are inserted in parallel through each duct (16 and 18, respectively) connecting to openings (14) in a housing (12), in which a rotor is provided (22), which has axial passage openings for gas flow, wherein the rotor is stored on a frame frame (28) extendable through a side dipping (36) in the housing, whereby seals (48 and 60 and 82, respectively) are arranged to counteract undesired leakage. past the rotor, characterized in that, in the extendable frame frame (28), a cross wall (56) is provided with a circular aperture (58) for the rotor (22), which is intended to abruptly abut the direction of movement of the frame with the frame frame. parallel sides (64, 66) via guide and sealing rails (68), wherein edges are cut at a right angle to the guide and sealing flanges (70, 72), which are parallel to and abutting flat against the life of said rails, that the two other sides of the cross-wall are intended to protrude mutually against the closed back of the housing (76) and a side aperture (38) closing and a circular aperture (60) supported by a cross-waveguide (60) arranged in the circular aperture 25 (58) to which an axially extending peripheral seal (82), respectively, is connected in the region of the frame frame (28). a diameter seal (48). 30 2. Heat exchanger according to claim 1, characterized in that the drive motor (40) is mounted on the crosswheel (56), preferably in a casing (78) built on the crosswheel. 35 3. Heat exchanger according to claim 1, characterized in that the door (38), which covers the housing opening (36), is fixedly mounted on the frame frame (28) and / or the transverse wave (56), so that the door is so constructed that it 91674 18 the abutment abuts against the outer edge of the cross-wall (56), and that the door (38) is extensible in one piece together with said frame frame (28) and said cross-wall (56). 5 Heat exchanger according to one or more of claims 1-3, characterized in that a power supply line (42) connected to the drive motor (40) is detachably connected to a stationary electrical outlet (not shown), and / or that the drive motor (40) The sealing box (44) is provided extendably together with the rotor (22) and the frame frame (28), preferably mounted on the crosswheel (56). Heat exchanger according to one or more of the preceding claims, characterized in that the crosswave (56) has at least one stiffening flange (74) which protrudes from the free spirit of a flange life (70, 72) abutting said rails in cooperative with them. 20 Heat exchanger according to claim 1, characterized in that said axially extending peripheral seals (82) have through-openings for accommodating the rotor drive belt (80). 25 Heat exchanger according to one or more of claims 1-6, characterized in that said radially directed peripheral seal (60) between the crosswave (56) and the peripheral surface of the rotor comprises a brush seal 30 (60a), a single or double fold elastic lug. , preferably a rubber pad (60b) having »I; : raised or folded side edges abutting against the mantle surface (62) or a multiple double lip seal (60c), and said sealing element (60a, 60b, 60c) is provided directly at the crosswheel (56) or with the aid of a wound fixing element (86) . il I · 91674 19 Heat exchanger according to any one of claims 1-6, characterized in that said radially directed peripheral seal (60) comprises a labyrinth seal, that part of the labyrinth seal is arranged on the two-cradle (56) and a part of the labyrinth seal is arranged on the rotor. peripheral surface (62), and the labyrinth seal either has radial projection (6Od) or sealing surfaces (60e) parallel to the peripheral surface (62) of the rotor 10 (22).