GB2049144A

GB2049144A - Plate heat exchangers

Info

Publication number: GB2049144A
Application number: GB7909081A
Authority: GB
Original assignee: APV Corp Ltd
Current assignee: SPX Flow Technology Crawley Ltd
Priority date: 1979-03-15
Filing date: 1979-03-15
Publication date: 1980-12-17
Also published as: GB2049144B

Abstract

A plate heat exchanger comprises a pack of separable plates 12 held in compression between a fixed head 14 and a follower 16 by a composite tie-bar 26 formed of at least two parts threadedly engaged together intermediate the head 14 and follower 16, to avoid undue projection of the tie-bar beyond the head 14 and follower 16. The composite tie-bar 26 preferably comprises a hollow member 27 which threadedly engages with a bolt 24. The hollow member 27 may be hinged to the frame. The composite tie-bar may alternatively be formed of solid components. <IMAGE>

Description

SPECIFICATION Improvements in or relating to plate heat exchangers The present invention relates to plate heat exchangers.

A plate heat exchanger of the type to which this invention relates consists of a pack of seperable plates in face-to-face spaced relationship in a frame and having peripheral gaskets to define flow spaces between the plates. The frame consists of top and bottom bars extending between a fixed head and a fixed end support. Conventionally the plates are slidable on the top and bottom bars and are compressed against the head by a follower which is slidable along the top and bottom bars and is linked to the head by threaded tiebars and nuts in engagement therewith. In the larger sizes of heat exchangers the tie-bars can weigh upwards of 200 kg each and hence the fitment and removal of the tie-bars is of major concern.

It is known to mount the tie-bars in slots in the edge of the head and the follower which allows easy fitment and removal of the tiebars. This method of mounting the tie-bar has the disadvantage that the tie-bars have to be restrained against falling out of the slots, for example, by bearing plates which locate on the frame. It also has the disadvantage of presenting fabrication problems and expense, for example, machining of the slots. If the tiebars are mounted in apertures in the frame these disadvantages are somewhat mitigated however, the advantage of easy fitment and removal of the tie-bars is lost since it is necessary to withdraw the tie-bars through the apertures, which requires an end clearance adjacent to the frame at least equal to the length of the tie-bars.

Thus, it is an object of the present invention to mitigate the disadvantages of the above methods of linking the head and the follower.

According to a first aspect of the present invention there is provided a plate-heat exchanger comprising a pack of seperable plates mounted on a frame which includes a fixed head and a follower, in which the pack of plates are held, or are adapted to be held in compression between the head and the follower by tie-bar means formed of at least two parts threadedly engaged together intermediate the head and follower.

According to a second aspect of the present invention there is provided a composite tie-bar comprising a bolt and a hollow member, wherein the bolt comprises a fixed head and a threaded shaft and the hollow member is provided with a threaded aperture at one end for engaging the shaft of the bolt and provided at the opposite end with means for joining the tie-bar to a frame.

It is advantageous that one part of the tiebar is joined at one end to the frame.

Preferably, where one part of the tie-bar is joined to the frame then that part is formed as a hollow member and is joined to the frame either by a hinge, by a threaded shaft rigidly joined therewith or otherwise.

The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows an embodiment of the present invention; Figure 2 shows a section through part of the embodiment shown in Fig. 1, drawn to a different scale; Figure 3 shows in plan view a form of linkage between one end of a tie-bar and the frame of the heat-exchanger; Figure 4 shows in plan view another embodiment of the invention; and Figure 5 shows a side view of the embodiment shown in Fig. 4.

Fig. 1 shows a plate heat exchanger 10 comprising a pack of separable plates 1 2 mounted on a frame between a head 14 and a follower 1 6 thereof. The frame also consists of a fixed end support 1 8 together with top and bottom bars, 20 and 22 respectively, which extend between the head 14 and the fixed end support 1 8. The separable plates 1 2 are slidable on the top and bottom bars, 20 and 22, and are mounted in face-to-face spaced relationship between the head 14 and the follower 1 6. The separable plates 1 2 are compressed between the head 14 and the follower 1 6 by composite tie-bars 26. The composite tie-bars 26 consist of bolts 24 threadedly engageable with hollow members 27.

Fig. 2 shows a section through part of the heat exchanger shown in Fig. 1 and consequently the same reference numerals are used to denote the same features. The hollow members 27 may be joined, rigidly or otherwise, or formed integrally with either the head 14 or the follower 16. In Figs. 1 and 2 the hollow members 27 are shown as hollow cylinders 28 closed at either end by a plug 30 and 32, rigidly joined therewith. The plug 30 at one end of each hollow cylinder 28 is provided with a threaded aperture which engages a bolt 24. Rigidly fixed with the plug 32 at the other end of each hollow cylinder 28 is a threaded shaft 34. The threaded shaft 34 extends through an aperture in the follower 16 and is there engaged by a nut 36.

The hollow members 27 may be internally reinforced. In the illustrated embodiment the bolts 24 extend through apertures in the head 1 4 of the frame.

Alternatively the hollow members 27 may be provided with threaded apertures at both ends so that it may be engaged at both ends by bolts 24, the bolts 24 being mountable on the frame of the heat exchanger.

In assembling plate heat exchangers with the use of composite tie-bars it may be necessary to prevent rotation of certain parts of the composite tie-bars depending upon the specific embodiment of the tie-bar.

This prevention of rotation may be achieved by the use of a tool' or by abutment or connection of the specific part of the tie-bar to a suitable support or by any other suitable means.

Many variations of the form of the composite tie-bars 26 are possible. The hollow cylinder 28, plugs 30 and 32 and the threaded shaft 34 may be replaced by a hollow member of any other configuration, or by a solid member, having a suitable cross-section, the replacement being joined to either the head 14 or the follower 1 6 and being provided with a threaded aperture suitable for engaging the bolt 24. In particular solid members having so called "channel sections" may be employed.

A preferred method of joining the hollow members 27 to the frame is to hinge them to either the head 14 or the follower 1 6. If the hollow members 27 are hinged to the frame, it is advantageous to mount the bolts 24 in slots in the edge of the respective part of the frame rather than in apertures in the frames, since this mitigates the necessity of lifting the tie-bars, or parts thereof, completely out of contact with the frame upon removal.

An alternative method of linking one end of a composite tie-bar to the frame of the heat exchanger is shown in Fig. 3. The end 38 of the tie-bar is provided with a lug 40 which is fixed to the end 38 of the tie-bar by means of a supporting bracket 44. The lug 40 mates with a recess 42 provided in the follower 1 6 and thus locates and links the tie-bar to the frame.

A preferred form of composite tie-bar which is hinged to the frame of the heat exchanger is shown in Figs. 4 and 5. The composite tiebar consists of a bolt 24, a member 46 and a clamping bracket 48. The clamping bracket 48 is suitably mounted on the follower 1 6 and provides a pin 50 to which the tie-bar member 46 is pivotally attached. The tie-bar member 46 is itself provided with a pin 52 at the end opposite to its attachment with pin 50. The pin 52 is rotatably mounted in the tie-bar member 46 and is provided with a threaded aperture for engaging the bolt 24.

The two hinges effectively formed by pins 50 and 52 are such that the respective parts of the tie-bars may be pivoted towards or away from the heat exchanger in a substantially horizontal plane when the tie-bar is in its operable position.

The use of composite tie-bars 26 has many advantages over the conventional tie-bar method of compressing the plates 1 2 between the head 14 and follower 1 6 of a heat exchanger 10. The fact that the length of thread used in compressing the pack of plates 1 2 can be stored within a hollow 27 part of a composite tie-bar 26 means that the tie-bar threads need not project from the head 14 or the follower 16. This enables the heat exchanger unit 10 to be more compact, improves safety since it reduces projections from the frame, improves protection of the tie-bar threads and can also facilitate pipe connections to the heat exchanger 10.

Where a composite tie-bar 26 includes a hollow member 27, this may contain a suitable lubricant for the threads of the bolts 24.

When the bolts 24 are mounted in apertures in the frame the disadvantages associated with mounting conventional tie-bars in apertures in the frame are somewhat mitigated due to the reduction in length of the member to be retracted. The use of composite tie-bars 26 including a hollow member 27 allows any multiplicity of standard stocked lengths of tiebars to be reduced since the bolts 24 may be engaged with the hollow members 27 to varying depths.

Claims

1. A plate heat exchanger comprising a pack of separable plates mounted on a frame which includes a fixed head and a follower, in which the pack of plates are held, or are adapted to be held, in compression between the head and the follower by tie-bar means formed of at least two parts threadedly engaged together intermediate the head and follower.

2. A plate heat exchanger as claimed in claim 1, wherein one part of the tie-bar is linked at one end to the frame.

3. A plate heat exchanger as claimed in claim 2, wherein the said part of the tie-bar is formed as a hollow member.

4. A plate heat exchanger as claimed in claim 3, wherein the hollow member is linked to the frame by way of a threaded shaft rigidly fixed to the hollow member.

5. A plate heat exchanger as claimed in claim 1, wherein the tie-bar means are formed as two bolts threadedly engaging opposite ends of an intermediate member.

6. A plate heat exchanger as claimed in claim 2, wherein the said part of the tie-bar is linked to the frame by way of a hinge.

7. A composite tie-bar comprising a bolt and a hollow member, wherein the bolt comprises a fixed head and a threaded shaft and the hollow member is provided with a threaded aperture at one end for engaging the shaft of the bolt and provided at the opposite end with means for joining the tie-bar to a frame.

8. A plate heat exchanger substantially as hereinbefore described with reference to the accompanying drawings.

9. A composite tie-bar substantially as hereinbefore described.