Method for cleaning plate heat exchanger and plate heat exchanger

Abstract

The invention relates to a method for cleaning a plate heat exchanger, in which method the plate pack (2) of the plate heat exchanger is removed from the outer casing, the plate pack (2) is stretched in its longitudinal direction so that the spaces between the plates of the plate pack increase, and then the plate spaces of the plate pack are cleaned.

Claims

1. A method for cleaning a plate heat exchanger comprising the steps of: (a) providing a plate heat exchanger comprised of: (i) a plate pack formed of a stack of circular heat exchange plates having outer perimeter edges and openings, the heat exchange plates being arranged so as to be adjacently stacked on top of each other and thereby establish respective spaces therebetween, wherein the plate pack has a height which defines a longitudinal direction thereof, wherein the plate pack includes opposed first and second ends in the longitudinal direction of the stack of heat exchange plates and an outer surface defined by the outer perimeter edges of the heat exchange plates, the heat exchange plates being attached to each other alternately at the openings and at the outer perimeter edges of the heat exchange plates, and (ii) an outer casing surrounding the plate pack, the outer casing comprising an end plate which is attached to the first end of the plate pack in the longitudinal direction thereof, and a shell surrounding the plate pack, wherein the end plate is removably connected to the shell so as to be openable relative to the shell and thereby allow removal of the end plate and the plate pack from the shell, (b) opening the outer casing by disconnecting the end plate from the shell of the outer casing, (c) removing the plate pack and the end plate from the outer casing, (d) positioning the removed plate pack and end plate relative to a support base so that the second end of the plate pack is supported by the support base opposite to the end plate at the first end of the plate pack, and positionally fixing the second end of the plate pack to the support base, (e) arranging a support and stretching mechanism relative to the plate pack in order to allow the plate pack to stretch evenly throughout a lengthwise extent of the plate pack along the longitudinal direction thereof by: (1) positioning at least one diametrically opposed pair of elongate screwing taps parallel to the longitudinal direction of the plate pack adjacent to the outer perimeter edges of the heat exchange plates, and operatively connecting each of the screwing taps to the support base and the end plate so that operation of the screwing taps changes a dimensional extent in the longitudinal direction of the plate pack between the support base and the end plate, (2) positioning at least one planar support plate having opposed terminal ends between a predetermined adjacent pair of the adjacently stacked heat exchange plates such that the planar support plate extends diametrically through the plate pack so as to span a diametrical distance between the pair of elongate screwing taps, and (3) removably attaching each of the terminal ends of the at least one planar support plate to a respective one of the elongate screwing taps, (f) stretching the plate pack in the longitudinal direction thereof so as to dimensionally increase the respective spaces between each of the adjacently stacked heat exchange plates of the plate pack in the longitudinal direction thereof, and (g) cleaning the dimensionally increased respective spaces between the adjacently stacked heat exchange plates of the plate pack.

2. The method according to claim 1, wherein the plate heat exchanger further comprises flow guides positioned at the outer surface of the plate pack, and wherein prior to step (f), the method further comprises the step of removing the flow guides from the outer surface of the plate pack.

3. The method according to claim 1, which further comprises providing the screwing taps as a fixed part of the plate pack, and wherein step (f) comprises operating the screwing taps to dimensionally increase the respective spaces between the adjacently stacked ones of the heat exchange plates of the plate pack in the longitudinal direction thereof.

4. The method according to claim 1, wherein step (f) comprises stretching the plate pack by a hoisting apparatus.

5. The method according to claim 1, wherein step (f) is practiced such that the lengthwise extent of the plate pack is stretched between about one to two times greater than an original lengthwise extent of the plate pack prior to stretching.

6. The method according to claim 1, which comprises providing U-shaped slots at each of the terminal ends of the planar support plate for removable engagement with a respective one of the elongate screwing taps.

7. The method according to claim 6, wherein the U-shaped slots are oppositely oriented relative to one another.

Description

DESCRIPTION OF THE DRAWINGS

(1) The invention will be described in more detail with reference to the appended drawings, in which

(2) FIG. 1 shows a plate heat exchanger according to an embodiment of the invention,

(3) FIG. 2 shows a plate pack construction according to an embodiment of the invention,

(4) FIG. 3 shows a plate pack construction according to an embodiment of the invention arranged on a support base,

(5) FIG. 4 shows a stretched plate pack construction according to an embodiment of the invention,

(6) FIG. 5 shows a stretched plate pack construction and a support plate arranged into the plate pack according to an embodiment of the invention,

(7) FIG. 6 shows a plate pack construction with a fixed stretching mechanism according to an embodiment of the invention,

(8) FIG. 7 shows the plate pack construction of FIG. 6 in a stretchable position,

(9) FIG. 8 shows a cross-section of the plate pack in a normal position, and

(10) FIG. 9 shows a cross-section of the plate pack in a stretchable position.

DETAILED DESCRIPTION OF THE INVENTION

(11) In FIGS. 1 to 9, the same reference numbers have been used for parts corresponding to each other, even though the parts marked with the same reference numbers can be different in different examples.

(12) FIG. 1 presents an openable plate heat exchanger according to an embodiment of the invention seen from the outside. The plate heat exchanger 1 comprises an outer casing surrounding the plate pack comprising end plates 3a, 3b and a shell 4 connecting the end plates. At least one of the end plates is arranged to be openable, i.e. the end plate 3a is fixed with removable fastenings 5 to the plate heat exchanger construction. The end plate 3a comprises inlet and outlet connections 6a, 6b for the first heat exchange medium flowing inside the plate pack. The inlet and outlet connections 7a, 7b for the second heat exchange medium are arranged through the outer casing of the plate heat exchanger.

(13) FIG. 2 illustrates a plate pack construction according to an embodiment of the invention, which is removed from the shell of the outer casing. On the outer surface of the plate pack 2 has been arranged flow guides 8 (only one flow guide is shown in the Figure). The flow guide 8 can be detached from the plate pack, since it has been fixed with detachable fastenings 15. The plate pack construction also comprises support end plates 9 arranged to the ends of the plate pack. The support end plate attached to the end plate 3a is out of sight in the Figures.

(14) FIG. 3 shows a plate pack construction of FIG. 2, when the flow guides are taken off, and when the plate pack is arranged on a separate support base 10 so that the inlet and outlet of the first heat exchange medium 6a, 6b are upwards. The plate pack construction is fixed to the support base 10 by using separate fastening means 11. The fastening means 11 are typically fixed to the support end plate 9 of the plate pack construction.

(15) FIG. 4 shows the plate pack 2 according to the invention in a stretchable position. In FIG. 4, the plate pack 2 has been stretched about two times longer in comparison to its normal position. The plate pack 2 can be stretched e.g. by using a hoisting apparatus 12, which is arranged in contact with the end plate 3a.

(16) FIG. 5 also shows the plate pack 2 in a stretchable position. Around the plate pack 2 has been arranged four screwing taps 13a, 13b, 13c, 13d or the like, which have been fastened to the support base 10 and to the end plate 3a. FIG. 5 also illustrates the arranging of a planar support plate 14 into the plate pack 2 according to an embodiment of the invention so that the plate pack 2 can be stretched evenly in the whole length of the plate pack. The support plate 14 will be arranged into the plate pack 2 between the heat exchange plates so that it extends diametrically through the plate pack with the oppositely oriented U-shaped slots 14a at each of the terminal ends of the support plate 14 being removably attached to a respective one of the screwing taps 13a, 13c or the like. Thus, the support plate 14 prevents the stretching of the plate pack 2 more in its upper part than in its lower parts.

(17) A plate pack construction with a fixed stretching mechanism according to an embodiment of the invention is shown in FIG. 6. On the outer surface of the plate pack 2 has been arranged a fixed stretching mechanism, such as screwing taps 16a-16c, and flow guides 8 (only one flow guide is shown in the Figure). The screwing taps 16a, 16b, 16c have been arranged around the plate pack. The ends of the screwing taps are fixed to the support ends 9 of the plate pack construction. The flow guide 8 has been fixed to the plate with fastenings 15 and so it can be detached from the plate pack before stretching.

(18) FIG. 7 shows the plate pack construction of FIG. 6 in a stretchable position. The screwing taps 16a, 16b, 16c have been extended to the desired length and also so the plate pack 2 has been stretched in relation to the extended screwing taps. With a fixed stretching mechanism shown in FIGS. 6 and 7, the plate pack can also be stretched when the plate pack is placed in a horizontal direction.

(19) FIGS. 8 and 9 illustrate a detailed cross-section of the plate pack in a normal and a stretchable position. The plate pack 2 has been formed of corrugated heat exchange plates 17, 18, 17, 18 having openings 21a, 21b. The plate pack has been made up of several plate pairs arranged on top of each other. Each plate pair has been formed of two heat exchange plates 17, 18; 17, 18 that have been joined together. The heat exchange plates are attached to each other alternately at the openings of the plates (a welding joint 20) and at the perimeters of the plates (a welding joint 19). The corrugations of the heat exchange plates, i.e. the grooves and the ridges between them, produces a diamond shape to the plate spaces. In a normal position of the plate pack as shown in FIG. 8, the heat exchange plates 17, 18, 17, 18 are closely against each other in all contacting points of the plates. When the plate pack 2 has been stretched, the spaces between the plates 17, 18, 17, 18 will increase as shown in FIG. 9. Thus, the cleaning of the plate spaces is easier than in the normal position.

(20) The invention is not restricted to the examples of the above description, but it can be modified within the scope of the inventive idea presented in the claims.