The present invention relates to a regenerative heat exchanger of the type set forth in the preamble of the following claim 1.

A heat exchanger of this type is known from the Swedish patent specification No. 176 375 showing setting means in the shape of rolling elements, which are mounted on the radially outer end portions of the sector plates, rolling on a flange extending around the periphery of the top side and bottom side of the rotor.

The idea was to maintain in this way a fixed gap between the ends of the sector plates and the top side and bottom side, respectively, of the rotor. The working environment of the rolling elements, however, proved to be too difficult. The bearings of the rolling elements were rapidly worn out and dirt and solid particles were rolled into the surfaces of the flanges and rolling elements resulting in break downs.

An improvement is suggested in the Swedish patent application No. 9302148-3 showing a similar heat exchanger where the rolling elements are replaced by setting units made of carbon or graphite with the advantages of being very resistant against high temperatures and acid atmosphere. Especially graphite is known for excellent lubrication properties and has like carbon proved capable of keeping the two flanges of the cylindrical part clean during deposition of a lubricating layer of carbon or graphite on the flanges. The result of this is, however, that the setting units are gradually consumed and must be replaced. The mechanical properties of setting units of this type are very varying, so that one or more units may be worn down such that the gap becomes zero at the same time as other units of one and the same supply are almost unaffected. Therefore, said patent application suggests that each setting unit is axially adjustable and completed with an adjacent, axially directed measuring rod, which from a rest position is instantaneously movable against and in contact with a corresponding flange and designed to indicate when the magnitude of the gap demands a forward adjustment of the unit a small distance such that the original gap is reset. This solution is not satisfying, either, because the varying and sometimes comparatively rapid wear reguires an extensive supervision.

The object of the present invention is to achieve a heat exchanger structure, which eliminates this inconvenience and which enables further improvements for limiting the demands of supervision. This is achieved,

according to the invention, with a heat exchanger having the characterizing features set forth in the following claims. The solution consists in the fact that each setting unit comprises at least one axial,through passage, which is connected to a pressure gas source supplying a sufficient pressure for the creation of a gas cushion between the setting unit and the end flange of the cylindrical part. By that, no mechanical connection exists between the setting units and the end flanges, and the wear between these parts mentioned above in connection with the previously suggested heat exchanger is eliminated. Owing to that, an up to now incomparably small gap can be maintained between the sector plates and the end flanges, and, accordingly, a drastic reduction of the leakage between said parts.

The outer ends of the sector plates are, as usual, balanced by means of counterweights such that a suitable bearing pressure is obtained. If the bearing pressure is set too low in order to reduce the gas pressure need to create the gas cushions, it may happen that the sector plates are thrown up a distance by pressure shocks from the heat exchanging media. Temporary pressure shocks can be counteracted by shock absorbers, but long term pressure shocks demand a higher bearing pressure, for instance by means of springs, which apply a pressure on the sector plates in the direction towards the ends of the cylindrical part, and, thus, also a higher pressure of the pressure gas source. This solution would be satisfactory under normal working conditions. It may happen occasionally, however, owing to different reasons, that the compressor or the gas pressure source supplying the setting units with compressed air gets into shut-down. The consequences of this will be that the setting units strongly, and sometimes violently, are pressed against the corresponding flange. The setting units may be injured already by that, and because it usually takes a rather long time until the shut¬ down is repaired, there is a risk of considerable injuries or at least a heavy wear of the setting units.

According to a preferred embodiment of the invention also this disadvantage is eliminated. This is achieved according to the invention with a heat exchanger having the characterizing features set forth in the following claim 2. A pressure gas source, or the same pressure gas source that feeds the setting units with pressure gas, is utilized for setting a predetermined bearing pressure of the sector plates against the flanges by means of pressure operated pistons acting upon the sector plates. If the gas pressure creating the gas cushions ceases, also the pressure operatin the pistons ceases, which results in an immediate relief of the pressure

from the sector plates upon the setting units, when they start sliding on the flanges.

The invention will now be described in more detail with reference to the accompanying drawings which schematically illustrate an exemplifying embodiment of a heat exchanger according to the invention, and in which Figure 1 is an axial section taken on line I-I of Figure 2, Figure 2 is a top end view of the heat exchanger with inlet and outlet ducts in section, and Figure 3 is an axial section taken on line III-III of Figure 1.

The drawings illustrate a conventional heat exchanger with a stationary housing structure 1 and a cylindrical rotor 2 containing a mass of heat regenerating material 3. The rotor 2 is provided with a hub 4, and a fixed top sector plate 5 to which a movable sector plate 6 is hinged, and a corresponding fixed bottom sector plate 7 with a movable sector plate 8. The purpose of the two sector plates 5,6 and 7,8 is to sealingly bear as good as possible on the top and bottom ends of the rotor 2 and by that separate the heat exchanging media flowing through the rotor.

Each of the radially outer ends of the movable sector plates (6,8) are for that purpose provided with two units 10, which comprise a setting means 11 for maintaining a certain gap between the ends of the sector plates 6,8 and an annular top and bottom end flange 12 fixedly attached to the rotor 2 around its top and bottom peripheries. Moreover, each unit preferably comprises also a measuring device, not shown, suitably of fibre optic type, for control measurement of the gap.

Figure 3 illustrates a part of the housing structure 1 and the top end flange 12 of the rotor 2 and the movable top sector plate 6. One of the units 10 is fastened with screws in an aperture in the sector plate 6, which unit comprises an outer sleeve 15 with a mounting flange 16, that is fastened with screws 18 on the sector plate 6 with an intermediate sealing ring 17.

At the top of the sleeve 15 there is an interior thread 19, and an inner sleeve 20 is positioned in the sleeve 15 with an upper part, which is provided with an external thread 21 partially screwed on the thread 19. At the bottom the inner sleeve 20 is provided with a sealing 22, which is sealingly applied against the inner wall of the sleeve 15. the top end 23 of the inner sleeve is closed and its bottom end is provided with a bottom plate 24 welded to the outer sleeve. On the under side of the bottom plate a setting means in the shape of a circular sliding shoe is replaceably fastened by means of a countersunk fastening screw 26 threaded into the

bottom plate and provided with an axial through channel 40 connecting the interior of the sleeve 20 with a recess 41 in the underside of the sliding shoe 25.

The mounting flange 16 of the outer sleeve 15 is provided with an axial flange 27 to which one end of an annular, slightly curved sealing bellow 28 is attached, the other end of which being attached to an axial sleeve 29 surrounding the unit 10 and positioned in a mounting hole in the housing structure 1 and attached to it by means of a mounting flange 30 and an intermediate sealing ring 31.

The top portion of the outer sleeve 15 is provided with a mounting lug 32 to which one end of a beam 33 is attached. The other end is in a corresponding way attached to the other unit 10 (not shown) supporting an end portion of a sector plate. According to the preferred embodiment a pressure cylinder 34 is attached to the housing structure 1, said pressure cylinder having a piston 35 and a piston rod 36 attached to the beam 33. A compression spring 37 is acting on the underside of the piston 35 and the pressure from a pressure gas conduit 38 is acting on the upper side of the piston. The conduit connects a pressure gas source (not shown) with a nipple 39 mounted in a through hole in the top portion of the top end 23 and provided with a channel to the interior of the sleeve 20 and a channel transmitting the pressure to the continuation of the conduit 38 to the cylinder 34. The weight of the sector plate 6 and associated equipment is mainly balanced by a balancing means (not shown) and the spring force from the spring 37. A bearing force of the sliding shoe 25 corresponding to a load of round 50 kg is created by a pressure of 2 bar in the sleeve 20 and in the cylinder 34 in combination with a suitable area of the piston 35. An air cushion is created on the underside of the sliding shoe 25 by the gas flowing out from the recess 41 such that the gap between the underside of the sliding shoe and the end flange 12 amounts to about 0.3 mm.

If the pressure in the conduit 38 should cease, the lifting force in the direction from the flange 12 also should cease together with the pressure force in the opposite direction from the piston 35 in the cylinder 34. Thereby and by the action of the spring 37 acting on the underside of the piston 35 the contact force of the sliding shoe 25 against the flange 12 will be sufficiently low to permit sliding of the sliding shoe on the flange 12 for a long time without damages and still with a reasonable sealing function of the sector plate till the break-down is repaired.

As previously mentioned the sliding shoes 25 and the cylinders 34

may be pressurized by two separate pressure gas sources. In this case cease of pressure to the sliding shoes should initiate a simultaneous cease of pressure to the pressure cylinders.

The gap between the sector plates 6 and the end flanges 12 is suitably as small as 1-3 mm. This is adjusted by turning of the upper portion 23 of the inner sleeve 20 by inserting a key into recesses in the upper portion 23 after loosening of a possible locknut which may be locked against the outer sleeve 15. A correct adjustment may be indicated for instance by the previously mentioned device of fibre optic type, which in the usual way may be arranged to control a motor-driven adjustment apparatus for turning the inner sleeve 20 and its top portion 23 as an alternative for the hand operated adjustment procedure, which of course cannot take place as frequent as a motor operated adjustment.

The invention is of course not restricted to the shown and described embodiment but may be modified in many ways without departing from the scope of the inventive idea defined by the claims.