GB2063449A

GB2063449A - Floating-head-tube Heat- exchangers

Info

Publication number: GB2063449A
Application number: GB7939529A
Authority: GB
Original assignee: Motherwell Bridge Thermal Ltd
Current assignee: Motherwell Bridge Thermal Ltd
Priority date: 1979-11-15
Filing date: 1979-11-15
Publication date: 1981-06-03
Also published as: GB2063449B

Abstract

A tube heat exchanger of the floating head type, Fig. 1, comprises a bonnet 25 with hand holes 26 permitting access to the interior thereof wherein is a funnel 20 releasably secured to the floating head tube sheet 18A and, by a releasable coupling 23, to a conduit 22 which extends from the bonnet. Access to the coupling 23 is gained through the hand holes 26. The funnel 20 is releasably secured to the sheet 18A by a segmented ring clamp arrangement 21 which is removable. The invention also includes a segmented-ring handling device 30, Fig. 4, which is fitted to the tube sheet 18A to permit removal of the tube bundle 16 from the casing 11, said device having an inwardly directed flange 33 and having an external diameter which is less than the bore of the casing. The device incorporates hoist attachment eye bolts 34 so that with lifting gear attached, the weight of the tube bundle 16 can be taken to permit the fixed end tube sheet 18B to be unclamped and the end cap 19 removed. <IMAGE>

Description

SPECIFICATION Floating-head-tube Heat-exchangers This invention relates to fioating-head-tube heat-exchangers.

In a floating-head-tube heat exchanger the tube bundle is secured at each end to a tube sheet and housed within a casing. The casing has a releasable cap at one end and a releasable bonnet at the other. A first tube sheet, which is of larger diameter than the bore of the casing, is clamped between the end cap and the casing, whilst the second tube sheet is of lesser diameter than the casing bore and floats adjacent (i.e. there is no connection to) the releasable connection of the casing with the bonnet. In order to convey fluid flowing to or from the individual tubes of the bundle a funnel is sealingly secured to the floating head tube sheet inside the bonnet and the funnel leads into a conduit which passes through a gland in the bonnet for connection to external pipework.

The end cap at the other end of the casing itself acts as a funnel and terminates in a flanged port to which external pipework may be secured. The casing has a fluid inlet port and a fluid outlet port.

The arrangement of the known floating-head tube heat-exchanger is such that when it is completely disconnected from external pipework and supporting structure the bonnet and the floating head funnel together with its conduit can be removed to permit the tube bundle to be withdrawn from the other end of the casing after release of the end cap. To permit disconnection of the funnel from the tube sheet the bonnet must first be disconnected from the casing, the packing pressure of the bonnet gland must be released and the bonnet must be slid along the conduit away from the casing. This can only be achieved if the length of the conduit protruding from the gland is sufficient to accommodate the required displacement of the bonnet to permit access to the coupling between the funnel and the tube sheet.

We have now devised an arrangement whereby the tube bundle can be withdrawn from the casing of a floating-head-tube heat-exchanger whilst the casing remains in situ and connected to its external pipework and support structure. Our arrangement is also advantageous in that since only the tube bundle is removed the handling equipment required need not be as robust as in the case where the entire exchanger is disconnected from external pipework and supporting structure.

According to the present invention there is provided a tube heat exchanger of the floatinghead type, wherein the bonnet has a plurality of hand holes permitting access to the interior thereof, the funnel which is secured to the floating-head-tube sheet and the conduit which extends through the gland in the bonnet being interconnected by means of a releasable coupling access to which can be gained through said hand holes.

It will be appreciated that since the present invention permits the funnel to be disconnected from the conduit with the bonnet in mating position on the casing the bonnet and the conduit can be removed as a unit from the heat exchanger whilst leaving the funnel in situ and there is no need for the length of the conduit to exceed that required to gain access to the gland of the bonnet.

Furthermore, depending upon the location of external pipework it may not be necessary to release the gland packing pressure since the released bonnet and conduit can be lifted clear of the funnel. Where space is restricted it would be possible to release the gland packing pressure and withdraw the conduit partly through the gland thereby separating the adjoining parts of the funnel and conduit and permitting the bonnet and conduit to be removed, as a unit, pivotally.

Preferably in the present invention the funnel is releasably secured to the tube sheet by a segmented ring clamp arrangement of greater external diameter than the bore of the casing, and a segmented-ring handling device is provided for attachment to the floating head tube sheet after removal of said funnel and segmented-ring clamp arrangement, the handling device having a radially-inwardly-directed flange for location on the tube-side of the tube sheet and having an external diameter less than the bore of the casing, whereby with lifting gear attached to the handling device the weight of the tube bundle can be taken to permit the fixed end tube sheet to be unclamped, the end cap to be removed, and the tube bundle to be thereafter lowered through the casing whilst the latter remains in situ and connected to its external pipework and support structure.

The present invention also provides a segmented-ring handling device for attachment to the floating head tube sheet of the heatexchanger after removal of the funnel therefrom, the handling device having a radially-inwardlydirected flange for location on the tube side of the tube sheet, an external diameter less than the bore of the heat-exchanger casing, and one or more formations to which a hoist may be attached.

An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings, in which Fig. 1 shows a floating-head-tube heatexchanger, partly in section, according to the present invention; Fig. 2 is an enlarged view of a detail; Fig. 3 is an enlarged view of a further detail; Figs. 4 and 5 show a handling device for use in removing the tube bundle from the heatexchanger of Fig. 1.

The heat exchanger 10 comprises a casing 11 secured to a support structure 1 2 and having fluid inlet and outlet ports 13, 14 respectively. The casing 11 is elongate and preferably mounted with its longitudinal axis vertical and each end is terminated by a flange 15, the top flange being denoted 15A and the bottom flange being denoted 15B. Within the casing 11 there is a tube bundle 1 6 which comprises a plurality of individual tubes 1 7 each of which is secured at its ends to apertured plates or tube sheets 18, the top sheet being denoted 1 8A and the bottom sheet being 1 8B. Sheet 1 8B is of larger diameter than the bore of the casing 11 and is clamped against flange 1 5B by the flange 1 9A of end cap 1 9 which is almost semi-spherical in shape and terminates in a flange port 1 9B to which external pipework (not shown) may be secured. The sheet 18A is of lesser dimension than the bore of the casing 11 and floats adjacent flange 1 5A so that in the absence of other components the tube bundle can be released from the casing 11 by releasing the flange 1 8B and lowering the tube bundle downwardly through the casing 11.

Secured to the flange 1 8B there is a funnel 20 having a flange 20A which is clamped by means of a circumferentially segmented clamp arrangement 21 of larger diameter than the bore of casing 11. The funnel 20, at its other end is secured to a conduit 22 by means of a releasable coupling 23 and the conduit 22 passes through a gland 24 in a bonnet 25 the flanged end 25A of which is secured to flange 1 5A of casing 11. The wall of the bonnet 25 includes a plurality of hand holes 26, preferably four in number, which are located so that access may be gained to coupling 23 from the exterior of the bonnet 25. The conduit 22 externally of the bonnet 25 terminates in a flanged port 22A to which external pipework may be connected.

Fig. 2 shows part of the bonnet 25, funnel 20 and associated components in greater detail whilst Fig. 3 shows part of the coupling 23 in greater detail. The conduit 22, as is shown in Fig.

3, is thick walled and is secured to funnel 20 at a flange 20B by means of a clamp ring 27 and copper-clad asbestos packing 28. It will be evident that by virtue of the location and number of the hand holes 26 easy access can be obtained to the coupling 23 so that coupling 23 can be released. In turn, after external pipework is disconnected from flanged port 22A and flange 25A is disconnected from flange 15A the bonnet 25 together with the conduit 22 can be lifted clear of the casing 11 with the tube bundle 16 and funnel 20 still in situ thereby permitting easy access to funnel flange 20A with its clamping arrangement 21.Alternatively, where headroom above flanged port 22A is not sufficient for this procedure the gland 24 may be released and conduit 22 moved longitudinally so that it is released from coupling 23 and the bonnet 25 and conduit 22 can then be removed in a pivotal movement about part of flange 25A. In either of these procedures it will be appreciated that the projection of conduit 22 beyond gland 24 plays no useful part in the dismantling procedure and therefore this distance, denoted A in Fig. 2, can be minimised thereby resulting in a saving of material.

In order to remove the tube bundle 16 from the casing 11 after the foregoing procedure has been completed the handling device 30 of Figs. 4 and 5 is preferably fitted to the floating-head tube sheet 18A. Device 30 is formed in two circumferential parts 30A, 30B which can be bolted together at mating flanges 31 A, 31 B.Each part 30A, 30B has an external diameter which is less than that of the bore of the casing 11 (as shown in Fig. 4) but at its lower edge has a radially-inwardly-directed flange 33 which can be located on the tube side of the tube sheet 18A. The face of the flange 33 which engages that of the tube sheet 18A may be planar or grooved in a manner complementary to that of the tube sheet 18A and when each part 30A, 30B is so located the flanges 31 A, 31 B can be bolted together and a hoist (not shown) attached to eye bolts 34 forming part of device 30 so that it can be lowered through the casing 11, assuming sufficient headroom beneath the casing 11 for the tube bundle 1 6 to be removed from beneath the casing 11 for cleaning purposes.Assembly of the heat-exchanger would take place by reversal of the foregoing procedures.

The handling device 30 therefore permits the tube bundle 1 6 to be removed from the casing 11 for the purposes of cleaning and/or repair in a relatively simple manner which permits this procedure to be undertaken relatively frequently (say about three or four times per annum) to enable the efficiency of the heat-exchanger to be maintained at its optimum level. With the larger sizes of such heat-exchangers the weights are of the order of 10 to 30 tons and the device 30 permits the majority of this weight to remain in situ (being the weight of the casing and associated parts) whilst only a fraction of this weight is handled by lifting gear during the dismantling procedure.

Although not specifically described above it will be understood that the various couplings, flange-connections, and glands are bolted together but other forms of releasable-secural means may be utilised.

Claims

1. A tube heat exchanger of the floating head type, wherein the bonnet has a plurality of hand holes permitting access to the interior thereof, the funnel which is secured to the floating-head-tube sheet and the conduit which extends through the gland in the bonnet being interconnected by means of a releasable coupling access to which can be gained through said hand holes.

2. A tube heat exchanger as claimed in claim 1, wherein the funnel is releasably secured to the tube sheet by a segmented ring clamp arrangement of greater external diameter than the bore of the casing, and a segmented-ring handling device is provided for attachment to the floating head-tube sheet after removal of said funnel and segmented-ring clamp arrangement, the handling device having a radially-inwardly-directed flange for location on the tube-side of the tube sheet and having an external diameter less than the bore of the casing, whereby with lifting gear attached to the handling device the weight of the tube bundle can be taken to permit the fixed end tube sheet to be unclamped, the end cap to be removed, and the tube bundle to be thereafter lowered through the casing whilst the latter remains in situ and connected to its external pipework and support structure.

3. A tube heat exchanger as claimed in claim 1, and substantially as hereinbefore described with reference to the accompanying drawings.

4. A segmented-ring handling device for attachment to the floating-head tube sheet of a tube heat exchanger of the floating head type after removal of the funnel therefrom, the handling device having a radially-inwardlydirected flange for location on the tube-side of the -tube sheet and having an external diameter less than the bore of the casing, and one or more formations to which a hoist may be attached.