EP0830555B1

EP0830555B1 - Rotary regenerative heat exchanger

Info

Publication number: EP0830555B1
Application number: EP96917770A
Authority: EP
Inventors: Kurt Karlsson; Dag Westerlund
Original assignee: ABB Air Preheater Inc
Current assignee: Alstom Power Inc
Priority date: 1995-06-08
Filing date: 1996-05-31
Publication date: 2001-02-21
Anticipated expiration: 2016-05-31
Also published as: HU220426B; CZ395697A3; DE69611827T2; DE69611827D1; SE9502100D0; EA199800032A1; SE504462C2; HUP9901902A3; SE9502100L; PL180711B1; CZ287006B6; EP0830555A1; EA000246B1; ATE199287T1; GR3035891T3; HUP9901902A2; ES2155939T3; PT830555E; WO1996041996A1; PL323794A1

Abstract

The invention relates to a regenerative, rotating heat exchanger of the kind having a cylindrical part containing regenerative mass and sector plates (6) separating media flows, which sector plates have outer ends provided with sliding shoes (25) displaceable perpendicular to the sector plates and lockable, and maintaining a predetermined clearance between the ends of the sector plates (6) and an edge flange (12) or similar member of the cylindrical part against which edge flange (12) the sliding shoes (25) are arranged to slide. The sliding shoes (25) have wearing surfaces made of carbon or graphite and can be screwed by a screwing mechanism (51, 52) forward some mm at a time in correspondence to the abrasion. According to the invention an essential reduction of the wearing velocity is obtained due to the fact that each sliding shoe is provided with a guiding means (23, 29) which at the forward displacement of the sliding shoe (25) prevents its turning thereby maintaining a constant abrasion pattern.

Description

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

A heat exchanger of this kind is known from for instance WO-A-9500809, which discloses support means in the shape of sliding shoes made of carbon or graphite. This is a material that will not be rapidly destroyed by the corrosive atmosphere that is prevailing where the sliding shoes are positioned and that can resist the actual high temperatures. Moreover the material has excellent lubrication properties and deposits a friction reducing layer of carbon or graphite on the flanges against which the sliding shoes are sliding. This results, however, at the same time in an abrasion of the sliding shoes that has proved to be difficult to foresee. For that reason it has been necessary for this kind of sliding shoes to complete the sliding shoes with measuring devices, which measure the clearance between the sector plates and the the flanges and enable in time, i.e. before the sector plates start scraping against the flanges, a screwing forward of the support means or sliding shoes a predetermined distance so that the intended clearance is restored.

It is a time consuming supervision and adjusting work that is needed, and therefore it is important to reduce this work as much as possible. Such a measure consists in a reduction of the contact pressure such that the abrasion is reduced. In order to bring the sliding shoes and accordingly the sector plates to follow the flanges at the thermal deformations of the cylindrical part a contact pressure of about 500 N is required at the sliding shoes which some times has proved to result in a comparatively rapid wearing down.

The object of the invention is to obtain a solution of the problem consisting in the rapid wearing down of the support means or sliding shoes.

This has according to the invention been achieved in that the support means and its socket are provided with a guiding means preventing the support means from turning in the socket.

The invention is based on the observation that the support means during operation are wearing in in conformity with the shape of the flanges and the irregularities present on the surface of the flanges, which occurs after a rather short time. After that the wearing is more moderate. When the clearance has to be restored a screwing forward of the support means is performed during turning of the support means an arbitrary angle. After starting of the operation it is scarcely likely that the scratches made by abrasion in the contact surfaces of the support means by the respective flanges shall get into exact the same angular position as before. Accordingly, new scratches will be made by abrasion forming an angle with the former scratches at each adjustment, which will result in an even more rapid wearing down at each adjustment than is the case after a change of sliding shoes.

Because the support means itself has bad wearing qualities the support means is, according to a preferred embodiment of the invention, unrotatably attached to a carrier movably journalled in the socket, which carrier is prevented from turning in the socket by guiding means.

The guiding means acting between the socket on one hand and the carrier and/or the support means on the other hand comprises preferably of a groove in one of the parts in which a pin protrudes attached to the other part.

The invention will be further explained through the following schematic description of an example of an embodiment of a heat exchanger according to the invention with reference to the accompanying drawing, of which

fig.1 is a partial axial section through the heat exchanger,

fig.2 is an axial section through a device with a sliding shoe at the end of a sector plate along line II-II of fig.1, and

fig.3 is a section along line III-III of fig.2 of a detail illustrating the guiding means of the carrier.

The heat exchanger shown 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 plate 5 with a movable sector plate 6 pivotally connected thereto and a corresponding lower fixed centre plate 7 and a 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 each of the

movable sector plates

6,8 are provided with at least one device, preferably two devices 10, which forms an adjustable support means 11 for maintaining a certain clearance between the ends of the

sector plates

6,8 and an upper and a lower annular edge flange 12 attached to the rotor 2 along its upper and lower peripheries. Each device further comprises a measuring device 13 for checking the clearance as shown more in detail in Fig.2 and in WO-A-9500809. As an alternative the

sector plates

6,8 may be rotatable in a manner known per se, and the regenerative mass stationary.

Fig.2 illustrates a part of the casing 1 and the upper end flange 12 of the rotor 2 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 10 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 a lid 19 and within the outer sleeve 15 there is an inner sleeve 20 having an upper part provided with a fixedly attached lid 21. At its lower end the outer sleeve 15 is provided with a packing 22, which sealingly contacts the exterior of the inner sleeve 20. The lid 21 on the upper end of the inner sleeve 20 is provided with an axial exterior groove 23 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 made of graphite or carbon is exchangeably 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 a radial threaded hole 27 into which a screw 28 is screwed which has a pin 29 protruding into the groove 23 thereby preventing turning of the inner sleeve 20 and the sliding shoe 25 in the outer sleeve 15 acting as a socket for the inner sleeve and sliding shoe.

In parallel with the device 10 a measuring device 13 is provided close at the side thereof within a flexible bellow 30 extending between the casing 1 and the sector plate 6. It comprises 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 of a flange 31 attached to the outer sleeve 15. Inside the tube 40 there is a measuring rod 43, the upper end of which coacting with a measuring member, not shown, for indicating the actual clearance between the underside of the sector plate and upper surface of the edge flange 12. The purpose of the measuring device 13 is a continuous supervision of the wearing of the sliding shoe 25 at the movement of the flange 12 with respect to the sliding shoe.

For obtaining an adjustment of the clearance the inner sleeve 20 together with the sliding shoe 25 are axially movable in the outer sleeve 15 with the pin 29 in the groove 23 permitting the movement of the inner sleeve 20 and the sliding shoe without turning. The displacement can be obtained in many ways. A simple and efficient device for this purpose comprises a hole 50 in the lid 21 in which a rod 51 is rotatably journalled and with a fine-pitch part extends through a fine-pitch hole 52 in the lid 19.

The sliding shoe 25 will be displaced in relation to the sector plate 6 by turning of the rod 51. When the intended displacement is obtained the angular adjustment of the rod 51 can be locked by two locking nuts 53, which are tightened mutually and against the lid 19. The adjustment of the rod 51 can, as an alternative, be obtained by a self-locking gear, which displaces a rod with smooth surface, fixedly connected to the lid 21, and extending through a hole in the lid 19.

Initially a clearance of for example 4 mm is adjusted between the sector plate 6 and the edge flange 12 by turning the rod 51 by means of a key, not shown, attached to the rod, which clearance can be read off by depressing the measuring rod 43 against the edge flange 12 and reading e.g. scale marks at the upper end of the rod. When the correct clearance is obtained the inner sleeve 20 is locked in relation to the outer sleeve 15 by tightening the locking nuts 53. The measuring rod 43 is arranged to spring back again to an initial position with the lower end surface flush with the underside of the sector plate 6 when depression of the rod ceases.

The sliding shoe 25 is exposed to wearing during operation and the sector plate 6 is slowly sinking towards the edge flange 12 to a corresponding degree. The actual clearance after some time of operation is checked by a slight depression of the rod 43 and reading of the magnitude of the depression. In a new heat exchanger the abrasion is rapid and the inner sleeve 20 must be screwed up and the sliding shoe be replaced. After that the inner sleeve is screwed in position again and a correct clearance is set. Then the abrasion will be essentially slower depending on the fact that a layer of carbon or graphite is deposited on the edge flange 12 by the first sliding shoe, which deposition is lubricating.

The right hand half of Fig.2 illustrates the device 10 provided with a fresh sliding shoe 25, and the left hand half illustrates a consumed sliding shoe 25. By using a suitable carbon/graphite quality the sliding shoe 25 can have an essentially larger height - essentially up to the lid 21 - if the guiding means 23,27-29 is adapted correspondingly.

Claims

Regenerative heat exchanger comprising two parts, one of which being rotatable in relation to the other around a common centre axis, in which one of the parts (2) is essentially cylindrical and contains a regenerative mass (3) and the remaining part (1) contains media ducts with axially directed inlets and outlets for heat emitting and heat absorbing media, which inlets and outlets are mutually separated by sector shaped plates (6,8) for sealing purposes positioned close to the end surfaces of the cylindrical part, which plates are pivotally connected to axially fixed centre plates (5,7) attached to said remaining part at the ends of the cylindrical part, which sector shaped plates (6,8) at their radially outer ends are provided with devices (10) each comprising at least one support means (11) for setting a clearance between the ends of the plates and an edge flange (12) or similar member at each end of the cylindrical part (2), which support means (11) is journalled axially displaceable in a socket (15) at the respective sector plate end (6,8) perpendicular to the sector plate and adjustable by means of a screw mechanism (50-53) attached to the sector plate end, characterized in that the support means (11) and its socket (15) are provided with a guiding means (23,29) preventing turning of the support means in the socket.
Heat exchanger according to claim 1, characterized in that the support means (25) is unrotatably attached to a carrier (20) movably journalled in the socket (15), and that the carrier is prevented from turning in the socket by the guiding means (23,29).
Heat exchanger according to claim 2, characterized in that the guiding means acting between on one hand the socket (15) and on the other hand the carrier (20) and/or the support means (25) comprises a groove in one of these parts, in which groove a pin (29) attached to the other part protrudes.