The present invention relates to a regenerative heat exchanger of the kind specified in the preamble of the following claim 1.

Such a heat exchanger is known e.g. through SE 176 375, disclosing a support in the form of rolling bodies, mounted in the outer ends of sector-shaped plates closed to both ends of the rotating part and rolling on a flange along the periphery at the top and bottom end of the rotor.

It was therethrough intended that a constant clearance should be possible to be maintained between the ends of the sector-shaped plates and the top and bottom end, respectively. The environment for the rollers, however, was found to be to severe. The bearings of the rollers were worn out rapidly and dirt and particles were by the rolling adhered on the flanges and the surfaces of the roller with break downs as a consequence.

It has been suggested to replace the rollers by sliding shoes as disclosed in JP, A, 63-315 891. These sliding shoes are made of ceramics in order to attain a high wear resistance. However, problems will occur if the sliding shoe becomes somewhat slanting due to mounting inaccuracy and/or thermal deformations. There will in such cases be a risk that the sliding shoe will contact the flange by only a small part of its sliding surface with unacceptable high contact pressure as a consequence. Furthermore some kind of external lubrication of the sliding surfaces is required or considerable friction losses has to be accepted.

The object of the invention is to attain a heat exchanger of the introductionally specified kind in which the drawbacks entailing the known heat exchangers are eliminated in a simple and

effective way. This has according to the invention been achieved in that the heat exchanger has got the features specified in claim 1.

Instead of using rollers or ceramic sliding shoes the invention thus employs sliding shoes of carbon or graphite. Such a sliding shoe eliminates the drawbacks with a sliding shoe of the known kind. In particular graphite has excellent lubrication properties and like carbon has an ability to maintain the flanges of the rotating body clean when adhering a lubricating layer of carbon or graphite on the flanges. The abrasion of the sliding shoe also secures a correct contact with parallel contact surfaces so that the contact takes place on the complete sliding shoe surface. Carbon and graphite also have a good acceptance of the high temperature and the acid environment that are present. By the abrasion of the sliding shoes they will gradually be consumed and have to be replaced. The degree of abrasion, however, will vary widely, so that one or more sliding shoes might be worn down so much that the clearance reaches zero, whereas other sliding shoes will be almost unaffected. According to the invention each sliding shoe is adjustable in a direction perpendicular to the contact surface and there is provided a measuring rod adjacent to the sliding shoe, which measuring rod is directed parallel to the adjustment direction. The measuring rod from a resting position can be momentary brought in contact with the related flange and indicates when the size of the clearance requires advance¬ ment of the sliding shoe a distance so that the initial clearance is restored.

The invention is particularly but not exclusively suitable for such heat exchangers where the plates are sector shaped plates located closed to the end surfaces of the cylindrical part so that the sliding shoes and measuring rods are axially directed.

The ends of the sector plates are in usual way balanced with counterweights so that a suitable contact pressure is attained. If that pressure is kept too low in order to reduce the wear on the sliding shoes, it sometimes happens that the sector plates are thrown up by pressure pulses from the heat exchanging media. In order to avoid to increase the contact pressure an embodi¬ ment of the invention has got the features specified in claim 4. Further advantageous embodi- ments of the invention are specified in the dependent claims.

The invention is further explained in the following with reference to the accompanying draw¬ ings of which fig. 1 is a partial axial section through a first preferred embodiment of a heat exchanger accord¬ ing to the invention, fig. 2 is a longitudinal section through the device with sliding shoe and measuring rod along line II-II of fig. 1 and fig. 3 is a section corresponding to that of fig. 1 but illustrating a second embodiment of the invention.

The heat exchanger illustrated in fig. 1 is of conventional type having a stationary casing 1 and a cylindrical rotor 2 containing the regenerative mass 3. The rotor has a hub 4 and an upper fixed sector shaped centre plate 5 with a movable sector plate 6 pivotally connected thereto and corresponding lower fixed centre plate 7 and movable sector plate 8. The two sets of plates 5, 6 and 7, 8 have the function to seal against the upper and lower ends of the rotor 2 as tight as possible and thereby separate the heat exchanging media flowing through the rotor.

For that purpose the radially outer ends of the movable sector plates 6, 8 are provided with two devices 10 each, which devices include a support for maintaining a certain clearance between the ends of the sector plates 6, 8 and an upper and lower annular edge flange 12 attached to the rotor along its upper and lower peripheries. Each device also includes a measuring device 13 for control measurement of the clearance, as shown in detail in fig. 2.

Fig. 2 illustrates a part of the casing and the upper edge flange 12 of the rotor and the upper movable sector plate 6. In a hole in the sector plate 6 one of the devices 10 is fixed by screws. The device includes an outer sleeve 15 with a mounting flange 16, which with an intermediate sealing ring 17 is attached to the sector plate 6 by means of screws 18.

At its upper end the outer sleeve 15 has an internal thread 19 and within the outer sleeve 15 there is an inner sleeve 20 having an upper part with an external thread, partly screwed into the thread 19. At its lower end the inner sleeve is provided with a packing 22, which sealingly contacts the inside of the outer sleeve 15. The upper end of the inner sleeve 20 is provided with a nut 23 welded thereto and its lower end is provided with a bottom plate 24 welded

thereto. On the underside of the bottom plate 24 a circular sliding shoe 25 of graphite or carbon is exchangeable attached by means of a recessed screw 26 screwed into the bottom plate 24.

The upper end of the outer sleeve 15 is provided with an external annular flange 27 to which the upper end of a sealing bellow 28 of metal is screwed by means of a mounting ring 29, an annular packing 30 and screws 31.

The lower end of the bellow 28 is provided with a mounting ring 32, which by means of screws 33 and an intermediate packing 34 is attached in a circular hole in the casing 1 so that a pre¬ determined contact pressure will occur between the sliding shoe 25 and the edge flange 12 due to the spring effect of the bellow 28.

In parallel with the device 10 and closed at the side thereof the measuring device 13 is provided. It includes a tube 40, attached with its lower end in a hole 41 in the sector plate 6 and with its upper end in a hole 42 in the flange 27, and thus extends within the bellow 28. Inside the tube there is a measuring rod 43, the upper end of which is fixed in the shown posi¬ tion to a sleeve 44 by means of a not shown spring and an external flange on the rod, which sleeve 44 is screwed on to the tube 40. In that position a scaled part 45 of the upper end of the rod 43 projects out through the sleeve 44, and the bottom end of the rod 43 is aligned with the underside of the sector plate 6.

Eventually, as shown, a measuring clock 50 having a measure probe 51 contacting the top end of the scaled part 45 can be provided.

The purpose of the measuring device 13 is to control the wear of the sliding shoe 25 caused by the movement between the sliding shoe and the edge flange 12.

Initially a clearance of e.g. 4 mm is set between the sector plate 6 and the edge flange 12 by turning the inner sleeve 20 by means of a not shown key applied to the nut 23, the clearance being detectable by pushing the rod 43 against the edge flange 12 and reading the scale at the upper end 45 of the rod or the measuring clock 50. When correct clearance is reached the inner

sleeve 20 is locked relative the outer sleeve by tightening a lock nut 46 provided on the thread 21. The rod 43 will spring up to the illustrated position as the pushing down thereof ceases.

The sliding shoe 25 during operation will be worn and gradually the sector plate 6 will correspondingly sink down towards the edge flange 12. The remaining clearance after a certain time of operation is controlled by a slight pushing down of the rod 43 and reading the size of the movement. In a new heat exchanger the wear is rapid and the inner sleeve 20 has to be screwed up and the sliding shoe 25 exchanged. Then the inner sleeve is screwed into position again and the correct clearance is set. Thereafter the wear will be much slower since the first sliding shoe has created a coating of graphite or carbon on the edge flange 12, which coating will have a lubricating effect. There might be great variations in the running life of the sliding shoes due to varying quality of the graphite or carbon. The trend can easily be detected by the measuring device 13 after exchange of the sliding shoe, and the controls can be made during operation manually or automatically at suitable intervals.

Pressure pulses from the heat exchanging media might affect the sector plates 6 and 8 to momentary be thrown up a short distance. This could of course be counteracted by setting a high contact pressure between the sliding shoes 25 and the edge flanges 12. That, however, is not suitable regarding the wear. According to a preferred embodiment of the invention there is instead provided a dampening device 60 between each movable sector plate 6, 8 and the casing

1. The dampening device 60 preferably is pneumatical and can be used as a complement to the spring effect of the bellows 28.

Fig. 3 illustrates an alternative embodiment of the invention according to which there is also or alternatively provided sealing plates 70 closed to the cylindrical surface of the cylindrical part

2. These plates 70 are vaulted to correspond to the cylindrical surface and are substantially rectangular. The plates are radially movable by means not shown and co-operate with axially directed edge flanges 71 at the upper and lower ends of the rotating part 2.

Between each movable plate 70 and the flanges 71 a certain clearance should be maintained which is accomplished by means of supports 11' of the same kind as the supports 11 used to maintain the clearance between the sector plates 6, 8 and the ends of the cylindrical part 2.

Also these supports 1 1 ' thus are adjustable, include sliding shoes of graphite or carbon and are provided with a meatring rod for controlling the clearance. When using both the sector-shaped sealing plates 6, 8 and the vaulted plates 70 it is possible to provide both with the supports according to the invention or to provide either of the sector plates or the vaulted plates with such and have a more simple mounting of the other plates.