WO2009061262A1

WO2009061262A1 - Heat exchanger

Info

Publication number: WO2009061262A1
Application number: PCT/SE2008/051160
Authority: WO
Inventors: Anette Harle; Sven Mellin; Niklas Bivefors; Göran Paulsson
Original assignee: Alfa Laval Corporate Ab
Priority date: 2007-11-05
Filing date: 2008-10-13
Publication date: 2009-05-14
Also published as: SE531685C2; SE0702439L

Abstract

A plate heat exchanger (100) with a roller cage (208) is provided. The roller cage (208) is capable of rolling along a longitudinal direction (206) of a support bar (106). The roller cage (208) includes a roller holder (304), a plurality of rollers (210, 212) and a pair of cradles (306, 308). The plurality of rollers (210, 212) is attached to the roller holder (304) and movably connected to the support bar (106). The pair of cradles (306, 308) includes a body portion (504) and an end portion (506) that is attached to the body portion (504). The body portion (504) supports a movable end plate (102) of the plate heat exchanger (100).

Description

HEAT EXCHANGER

FIELD OF THE INVENTION

The present invention relates, in general, to the field of heat exchangers, and more specifically, to a roller cage for facilitating the movement of plates of heat exchangers.

BACKGROUND OF THE INVENTION

Heat exchangers are used to transfer heat between two fluids that are separated by a solid body. Heat exchangers can be of several types, e.g., spiral heat exchangers, tubular heat exchangers and plate heat exchangers (PHEs). PHEs are used to transfer heat between a hot fluid and a cold fluid that flow in alternate flow passages formed between a set of heat-transfer plates. The set of heat-transfer plates is enclosed between a pair of end plates that are relatively thicker and heavier than the heat-transfer plates. The inner surface of each end plate faces the set of heat-transfer plates. This entire arrangement is supported by a support bar, which comprises a carrying bar at the top and a hanging bar that is attached to the carrying bar.

Traditionally, one end of the support bar is attached to one of the end plates and the other end of the support bar is attached to a support column. The end plate attached to one of the ends of the support bar is referred as a fixed end plate. The fixed end plate is immovable and is attached to the ground with the help of a variety of attachments means such as screws, bolts, etc. The other end plate is movably attached to the support bar by means of a roller assembly, and hence, is known as a movable end plate.

The roller of the roller assembly is attached to the movable end plate by means of a bar-like attachment means and is capable of rolling along the carrying bar. The hanging bar passes through a recess in the movable end plate and acts as a guide for the movement of the movable end plate along the support bar. However, this arrangement has several disadvantages. The arrangement makes the roller assembly dependent on the profile of the carrying bar. In the event of a change in the profile of the carrying bar, the dimensions of the roller assembly need to be adjusted to ensure its smooth functioning. Additionally, the arrangement makes the movable end plate dependent on the profile of the hanging bar. As a result, any change in the profile of the hanging bar needs a corresponding alteration in the recess in the existing movable end plate or a new movable end plate that matches the profile of the new hanging bar. This results in alterations having to be made in the manufacturing designs, and thus increases the cost of the PHE. Further, as the roller assembly rolls along the top surface of the carrying bar in the existing arrangement, the surface finish of the carrying bar is affected over a period of time. This results in unevenness in the surface of the carrying bar, and hampers the movement of the rollers. To avoid this, periodic surface treatment of the carrying bar is required, which adds to the maintenance cost of the PHE. Furthermore, the presence of the roller at the top of the carrying bar adds to the height of the PHE. This makes packaging and transportation of the PHE tedious, since road regulations limit the possible overall height of the load that can be transported by a truck or other standard transportation means. In light of the foregoing facts, there is a need for a roller assembly that can overcome the various disadvantages of the existing arrangement and still ensure that the PHE is easily assembled and disassembled.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a heat exchanger, for example, a plate heat exchanger, with a roller cage that facilitates the movement of a movable end plate of the heat exchanger.

Another object of the present invention is to provide a heat exchanger, for example, a plate heat exchanger, whose movable end plate is independent of the profile of a support bar of the heat exchanger. Yet another object of the present invention is to provide a heat exchanger, for example, a plate heat exchanger with its roller cage being independent of the profile of the support bar of the heat exchanger.

To achieve the objects of the present invention, a heat exchanger with at least one movable end plate and at least one fixed end plate is provided. The at least one movable end plate and the at least one fixed end plate include a stack of heat-transfer plates that are arranged in between them. Further, the heat exchanger includes a roller cage that is attached to the at least one movable end plate, and a support bar that is attached to the at least one fixed end plate at one end. The support bar includes a carrying bar. The ends of the carrying bar are attached to the at least one fixed end plate and a support column. The support bar also includes a hanging bar that is attached to at least a part of the carrying bar. The hanging bar guides the movement of the roller cage, which is capable of rolling along the longitudinal direction of the support bar. The roller cage includes a roller holder, a plurality of rollers and a pair of cradles. The roller holder includes a pair of half-axles that protrude from the roller holder and are aligned along a common axis. The plurality of rollers is attached to the roller holder and is movably connected to the support bar. The pair of cradles corresponds to the pair of half-axles and each cradle of the pair of cradles includes a body portion and an end portion. The body portion is aligned along the longitudinal direction and has a concave surface that rests on the corresponding half-axle. Further, a dimension of the body portion along a first direction decreases gradually while moving outwards from the concave surface along the longitudinal direction. The first direction is mutually perpendicular to the longitudinal direction and the common axis. The end portion is attached to the body portion such that a thickness of the end portion remains substantially perpendicular to a thickness of the body portion. Further, the end portion has a plurality of recesses at the edges of the end portion. The at least one movable end plate also has a plurality of recesses that correspond to the plurality of recesses on the end portion. A plurality of attachment means can attach the roller cage to the at least one movable end plate by sliding through the plurality of recesses on the end portion and the correspondingly aligned plurality of recesses on the at least one movable end plate, to facilitate the attachment of the end portion to the at least one movable end plate. Further, the pair of cradles can execute a rocker motion about the common axis. In an embodiment, the rocker motion can range from 3 to 7 degrees about the common axis. In another embodiment, the rocker motion can range from 4 to 5 degrees about the common axis. In an embodiment, the movable end plate includes a cut-out in which the roller cage is received. Further, a part of the movable end plate is supported on a surface of the body portion. This enables locking each cradle of the pair of cradle to the corresponding half-axle of the pair of half-axles. In an embodiment, the surface of the body portion supporting at least a part of the at least one movable end plate is curved or crowned.

Other features and advantages of this invention will become apparent in the description.

BRIEF DESCRIPTION OF THE FIGURES The preferred embodiments of the invention will hereinafter be described in conjunction with the appended drawings that are provided to illustrate and not to limit the invention, wherein like designations denote like elements, and in which:

FIG. 1 illustrates a plate heat exchanger, in accordance with the state of the art;

FIG. 2 illustrates cross-sectional views of a roller cage that is attached to a movable end plate and a support bar, in accordance with an embodiment of the present invention;

FIG. 3 illustrates a complete assembly of a roller cage with an attachment means for attaching the roller cage to a movable end plate of a plate heat exchanger, in accordance with an embodiment of the present invention;

FIG. 4 illustrates a roller holder, in accordance with another embodiment of the present invention; FIG. 5 illustrates a cradle of a pair of cradles, in accordance with an embodiment of the present invention; and FIG. 6 illustrates orientations of a movable end plate, in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION

While the preferred embodiments of the invention have been illustrated and described, it will be clear that the invention is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions and equivalents will be apparent to those skilled in the art, without departing from the spirit and scope of the invention, as described in the claims.

Selected embodiments of the present invention will now be explained with reference to the drawings. From this disclosure, it will be apparent to those skilled in the art that the following description of the embodiments of the present invention is provided for illustration only, and not for the purpose of limiting the invention, as defined by the appended claims.

A wide variety of industries and processes, such as chemical and power plants, refrigeration, air-conditioning, etc., require effective means for heat transfer according to industrially acceptable standards during their various ongoing processes. This results in a need for the use of heat exchangers. A heat exchanger is a device that is used for transfer of heat from one fluid to another in an efficient manner, with or without a direct contact between the fluids.

Heat exchangers can be classified into two major groups, based on the pressure of fluids flowing through them. Generally, a shell and tube heat exchanger is used for high-pressure applications. This shell and tube heat exchanger is the most common type of heat exchanger used in oil refineries and other large chemical processes. As the name suggests, a shell and tube heat exchanger includes a shell that is a large pressure vessel, and a bundle of tubes passing through the shell. One of the fluids runs through the shell and the other through the tubes. Heat is transferred from one fluid to another through the outer tube walls that are in contact with the fluid flowing through the shell. A plate heat exchanger (PHE) is typically used for medium and low- pressure applications. Fig. 1 illustrates a PHE (100), in accordance with the state of art. The PHE (100) uses metal plates, hereinafter referred to as heat- transfer plates, to transfer heat between two fluids flowing through the PHE (100). The heat-transfer plates are thin and have a corrugated surface. This arrangement is more efficient as compared to the shell and tube heat exchangers, since the fluids are exposed to a much larger surface area.

Additionally, the corrugated surface increases turbulence, and, as a result of the increased turbulence, the rate of heat transfer also increases.

The heat-transfer plates can be joined to form a stack (112) by welding, gluing, brazing, soldering or using gaskets, depending on the application. For most applications, the stack (112) is formed by using gaskets to easily disassemble the stack (112) for periodic cleaning and inspection. The stack (112) includes multiple parallel flow passages between the heat-transfer plates, to enable the flow of the two fluids (hot fluid and cold fluid). The hot fluid and the cold fluid can be made to flow through alternate flow passages to transfer heat between them.

In practice, the stack (112) is enclosed between a pair of end plates (102, 104) that are relatively heavier and thicker than the heat-transfer plates. The main objective of the pair of end plates (102, 104) is to provide a rigid frame to the stack (112) of heat-transfer plates. The pair of end plates (102, 104) is arranged in such a manner that one end plate is placed at each end of the stack (112). The inner surface of each end plate of the pair of end plates (102, 104) faces the stack (112) of heat-transfer plates. The end plates (102, 104) are not involved in the process of heat transfer. Additionally, in some embodiments of the present invention, the end plates (102, 104) can also have at least one inlet opening (114) and at least one outlet opening (116), as shown in FIG. 1 , for the hot fluid and the cold fluid.

One of the end plates of the pair of end plates (102, 104), hereinafter referred to as the fixed end plate (104), is immovable and is attached to the ground, One end (the lower end) of the fixed end plate (104) can be attached to the ground by using various attachment means that are known in the art, e.g., screws, bolts, welding, etc. Another end (upper end) of the fixed end plate (104) has a plurality of recesses (not shown in the figure) for attaching the fixed end plate (104) to a support bar (106).

The other end plate (102) is attached to a roller assembly (110) by using fastening means such as welding, screws, nuts, etc. Due to the roller assembly (110) the other end plate (102), hereinafter referred to as the movable end plate (102), is capable of moving along a longitudinal direction of the support bar (106). This movement of the movable end plate (102) facilitates dismantling of the PHE (100) for periodic cleaning and inspection.

The main objective of the support bar (106) in the PHE (100) is to provide support to the pair of end plates (102, 104), to maintain the stack (112) in the desired position. The support bar (106) also acts as a guide for the movement of the movable end plate (102) and the stack (112) of heat-transfer plates along the longitudinal direction of the support bar (106).

The support bar (106) can be of different cross-sections, such as I- section, C-section, Z-section, etc. Further, as described above, one of the ends of the support bar (106) is attached to the fixed end plate (104), and the other end is attached to a support column (108) that is fixedly attached to the ground.

The support column (108) bears a fraction of the load of the stack (112) and the movable end plate (102). As a result, the design and cross-section of the support column (108) needs to be chosen carefully, so that it is sufficiently strong. The support column (108) can have a different cross-sectional shape, such as l-section, C-section, Z-section, etc., depending on the load supported by the support column (108).

The roller assembly (110) that is attached to the movable end plate (102) can roll along the top surface of the support bar (106), as shown. The two ends of the roller assembly (110) are attached to the movable end plate (102) in such a manner that the movable end plate (102) can move with the roller assembly (110). Further, the roller assembly (110) can be attached to the movable end plate (102) by using various attachment means known in the art, e.g., screws, bolts, welding, etc.

FIG. 2 illustrates cross-sectional views of a roller cage (208) that is attached to the movable end plate (102) and the support bar (106), in accordance with an embodiment of the present invention. The support bar (106) includes an upper portion, hereinafter referred to as a carrying bar (204). A first end of the carrying bar (204) can be attached to the fixed end plate (104) and a second end of the carrying bar (204) can be attached to the support column (108). The carrying bar (204) can be attached to the fixed end plate (104) and the support column (108) with the help of various attachment means known in the art, such as screws, bolts, welding, etc. Since the carrying bar (204) bears the load of the stack (112) and the movable end plate (102), the cross-section of the carrying bar (204) needs to be chosen carefully, depending on the load it will support. In various embodiments of the present invention, the carrying bar (204) can have a different cross-sectional shape such as l-section, C-section, Z-section, etc.

Further, the support bar (106) includes a lower portion, hereinafter referred to as a hanging bar (202). In various embodiments of the present invention, the hanging bar (202) can be attached in a variety of ways to the carrying bar (204). In one embodiment of the present invention, the hanging bar (202) can be an inherent part of the carrying bar (204). In another embodiment of the present invention, the hanging bar (202) can be attached in a removable manner by using means known in the art, such as screws, bolts, etc. In yet another embodiment, the hanging bar (202) can be permanently attached to the carrying bar (204) by using means known in the art, such as welding.

The hanging bar (202) guides the motion of the roller cage (208), and the movable end plate (102) attached to the roller cage (208), along a longitudinal direction (206) of the support bar (106). The hanging bar (202) also guides the motion of the stack (112) of heat-transfer plates along a longitudinal direction (206) of the support bar (106).The roller cage (208) includes a plurality of rollers (210, 212). In one embodiment, the plurality of rollers (210, 212) can be arranged in the form of a pair of set of rollers (210, 212). Each set of the pair of the set of rollers (210, 212) includes two rollers. The pair of the set of rollers (210, 212) is movably connected to the hanging bar (202) in such a way that it can move on the surface of the hanging bar (202). Further, the pair of the set of rollers (210, 212) are placed in such a manner that one set of rollers (210) is on one side of the hanging bar (202) and another set of rollers (212) is on the other side of the hanging bar (202), as shown in FIG. 2.

FIG. 3 illustrates a complete assembly of the roller cage (208) with an attachment means (302) for attaching the roller cage (208) to the movable end plate (102) of the PHE (100), in accordance with an embodiment of the present invention. The roller cage (208) includes a roller holder (304, which is described in further detail in conjunction with FIG. 4. The roller cage (208) also includes a plurality of rollers (210, 212) that is attached to the roller holder (304). The plurality of rollers (210, 212) is movably connected to the support bar (106), as described in FIG. 2. Further, the roller cage (208) includes a pair of cradles (306, 308), which is described in further detail in conjunction with FIG. 5. The attachment means (302) for attaching the roller cage (208) to the movable end plate (102) of the PHE (100) can include various attachment means known in the art, such as screws, bolts, etc. FIG. 4 illustrates the roller holder (304), in accordance with an embodiment of the present invention. One of the objectives of the roller holder (304) is to hold the plurality of rollers (210, 212). In one embodiment, the plurality of rollers (210, 212) can be arranged in the form of a pair of set of rollers (210, 212). Each set of the pair of the set of rollers (210, 212) includes two rollers. Further, the pair of the set of rollers (210, 212) is attached to the roller holder (304) in such a manner that it is located in the space defined by the pair of walls (406, 408) of the roller holder (304). Further, one set of rollers (210) is attached to one inner surface of the wall (406) of the roller holder (304) by means of a shaft (not shown in FIGS.) that extends through a corresponding hole 410 (schematically shown in FIG. 4) in the wall (406). The shaft is held in its place by using means known in the art such as locking screws. The locking screws can be slide through a pair of holes (412), as shown in FIG. 4. The other set of rollers (212) are identical to the set of rollers (210) and is attached to another inner surface of the wall (408) of the roller holder (304) in a manner identical to that of the set of rollers (210).

Each roller of the pair of the set of rollers (210, 212) is attached to the roller holder (304) about an axle. The axis of the axle of each roller of the pair of the set of rollers (210, 212) is parallel to a common axis (314), as shown in FIG. 4. Further, each roller of the pair of the set of rollers (210, 212) is attached to the roller holder (304) in a manner that enables free rotation of the roller about the axis of the axle. This ensures the smooth rolling motion of the roller on the surface of the hanging bar (202) along a longitudinal direction (206). Further, the pair of the set of rollers (210, 212) is positioned at a distance apart from each other so that at least a portion of the hanging bar (202) can pass between the pair of the set of rollers (210, 212). Furthermore, the pair of the set of rollers (210, 212) is placed in such a manner that one set of rollers (210) is on one side of the hanging bar (202) and another set of rollers (212) is on the other side of the hanging bar (202), as shown in FIG. 2.

The roller holder (304) also includes a pair of half axles (402, 404) that correspond to each cradle of the pair of cradles (306, 308). Each half axle of the pair of half axles (402, 404) protrudes from the roller holder (304). As shown in FIG. 4, a half axle (402) of the pair of half axles (402, 404) protrudes from one of the surfaces of the roller holder (304). Another half axle (404) of the pair of half-axles (402, 404) is identical to the half-axle (402) and protrudes from the roller holder (304) in an identical manner. In one embodiment, the pair of half axles (402, 404) is aligned along the common axis (314). The common axis (314) is positioned in a direction that is perpendicular to the longitudinal direction (206) in the plane of the protrusion of the pair of half-axles (402, 404).

Another objective of the roller holder (304) is to provide support to the pair of cradles (306, 308). Each cradle of the pair of cradles (306, 308) is supported on the corresponding half axle of the pair of half axles (402, 404). The cradle (306) corresponds to the half axle (402). Similarly, the cradle (308) corresponds to the half axle (404).

FIG. 5 illustrates the cradle (306) of the pair of cradles (306, 308), in accordance with an embodiment of the present invention. The cradle (306) includes a body portion (504), which is aligned along a longitudinal direction (206). A surface of the body portion (504) supports at least a portion of the movable end plate (102), hereinafter referred to as the top surface. For this purpose, the top surface of the body portion (504) corresponds to the mapping surface of the movable end plate (102). For example, if the top surface of the body portion (504) is flat, the mapping surface of the movable end plate (102) will also be flat. However, if the top surface of the body portion (504) has a groove (female portion), the mapping surface of the movable end plate (102) also has a corresponding protrusion (male portion).

In an embodiment, the top surface of the body portion (504) can be curved to match the irregularities of the mapping surface of the movable end plate (102). The curved top surface of the body portion (504) enables the even distribution of the load of the movable end plate (102) on the top surface of the body portion (504). The curved top surface of the body portion (504) also ensures that the load of the movable end plate (102) is located substantially at the centre of the mapping surface of the movable end plate (102) and not at the ends of the mapping surface of the movable end plate (102). In another embodiment, the top surface of the body portion (504) can be crowned to match the irregularities of the mapping surface of the movable end plate (102).

Further, to achieve the above mentioned objective the movable end plate (102) includes a cut-out in which the roller cage (208) is received. Upon receiving the roller cage (208) in the cut-out, a portion of the movable end plate (102) is supported on it. The portion of the movable end plate (102) supported on the roller cage (208), i.e. the mapping surface of the movable end plate

(102), locks the pair of cradles (306, 308) to the roller holder (304) of the roller cage (208). This is due to the fact that the distance (H1 ) between the cut-out edges and the roller holder (304) is less than the distance (H2) between each cradle of the pair of cradles (306, 308) and the corresponding half-axles of the pair of half-axles (402, 404), as can be seen from FIG. 2 and FIG. 3.

Another surface of the body portion (504), hereinafter referred to as the bottom surface, includes a concave surface (502). The concave surface (502) is located at the centre of the bottom surface of the body portion (504). Further, the concave surface (502) rests on the corresponding half axle (402). In one embodiment, the diameter of the concave surface (502) is equal to that of the corresponding half-axle (402). As a result, the concave surface (502) fits exactly on the corresponding half axle (402). The dimension of the body portion (504) decreases gradually while moving outwards from the concave surface (502) along the longitudinal direction (206) on either side of the concave surface (502). The decrease in the dimension of the body portion (504) is along a direction, hereinafter referred to as a first direction, the first direction lying along a surface of the body portion (504) perpendicular to the common axis (314), parallel to the Y axis, as shown in FIG. 5. As can be seen clearly from the FIG. 5, the first direction is mutually perpendicular to both the longitudinal direction (206) and the common axis (314). It can also be described as the body portion (504) is wedge formed on either side of the concave surface, where the wedge form or shape is formed by having the thinner part at the end of the body portion (504) and the thicker part at the concave surface (502).

Due to the gradual decrease of the dimension of the body portion (504), the surface on each side of the concave surface (502), while moving outwards from the concave surface along the longitudinal direction (206), as described above, are at an angle (α) to the plane of the corresponding half axle (402).

The angle (α) enables the cradle (306) to perform a rocker motion about the common axis (314), to provide tolerance for the misalignment of the movable end plate (102) during the motion of the movable end plate (102) along the longitudinal direction (206).

The cradle (306) also includes an end portion (506) at one of the ends of the cradle (306). In one embodiment, an extension of the end portion (506) is substantially perpendicular to an extension of the body portion (504). In other words, the extension of the end portion (506) that is perpendicular to the extension of the body portion (504) is substantially perpendicular to the common axis (314). In one embodiment, the end portion (506) can be fixedly attached to the body portion (504) by using various attachment means known in the art, such as welding, screws, bolts, etc. In another embodiment of the present invention, the end portion (506) can be an integral part of the cradle (306).

The end portion (506) includes a plurality of recesses (316). In one embodiment, the plurality of recesses (316) originates at one or more edges of the end portion (506) with an inward growth along the common axis (314), as shown in Fig. 3. The objective of the plurality of recesses (316) is to enable the attachment of the movable end plate (102) to the cradle (306), to allow the movable end plate (102) to move with the roller cage (208) in the longitudinal direction (206). A plurality of recesses or holes is also present on the movable end plate (102), to attach the movable end plate (102) to the end portion (506) of the cradle (306).

The plurality of recesses on the movable end plate (102) corresponds to the plurality of recesses (316) on the end portion (506). Further, the plurality of recesses on the movable end plate (102) is aligned to the plurality of recesses (316) on the end portion (506) when the mapping surface of the movable end plate (102) is placed on the top surface of the body portion (504). After placing the mapping surface on the top surface, the attachment means (302) can slide through the aligned recesses and recesses to enable the attachment of the movable end plate (102) to the end portion (506) of the cradle (306). In various embodiments of the present invention, various means such as screws, bolts, etc., can be used as attachment means (302).

In another embodiment, a part of the roller cage (208) can slide through a corresponding hole on the movable end plate (102), to enable the attachment of the roller cage (208) with the movable end plate (102).

FIG. 6 illustrates various orientations of the movable end plate (102) that result from the rocker motion of the pair of cradles (306,308) about the common axis (314), in accordance with an embodiment of the present invention. As described above, the rocker motion enables tolerance for the misalignment of the movable end plate (102) while the movable end plate (102) is moving along the longitudinal direction (206).

The range of the rocker motion can vary, depending on the range of the angle (α) in various embodiments. In various embodiments, the angle (α) can range from 3 to 7 degrees. Further, in a preferred embodiment, the angle (α) is 4 to 5 degrees.

In the foregoing specification, the invention has been described with reference to PHE (100). However, one with ordinary skill in the art would appreciate that the present invention can also be practiced as an arrangement to facilitate the movement of a load on a support bar. Further, various modifications and changes can be made, without departing from the scope of the present invention, as set forth in the claims. The present invention provides various advantages and reduces the manufacturing and maintenance costs of a PHE. The present invention also makes the roller assembly independent of the profile of the carrying bar. As a result, the same roller assembly can be used, irrespective of the profile of the carrying bar used in the PHE. Moreover, the present invention makes the movable end plate independent of the profile of the hanging bar. Hence, even if there is a change in the profile of the hanging bar, a corresponding alteration in the movable end plate is not required. Further, since the roller assembly rolls along the surface of the hanging bar, the finish of the top surface of the carrying bar does not get affected. This eliminates the costs incurred on periodic maintenance activities such as surface treatment of the top surface by using carrying bars. It also eliminates the problem with dirt on the top surface that prevents the rollers to roll unhindered on the top surface.

Additionally, the absence of rollers on the top surface of the carrying bar provides an unhindered top surface, facilitating the process of packaging and transporting the PHE.

The foregoing description of the present invention has been presented for the purpose of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and other modifications and variations may be possible in light of the details given above. The embodiment was chosen and described to best explain the principles of the invention and its practical application, thereby enabling others skilled in the art to utilize the invention in various embodiments and modifications, as suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments of the invention, except insofar as limited by the prior art.

Claims

WHAT IS CLAIMED IS:

1. A plate heat exchanger (100) comprising at least one movable end plate (102) and at least one fixed end plate (104), the at least one fixed end plate (104) attached to a support bar (106), the at least one movable end plate (102) attached to a roller cage (208), a stack (112) of heat-transfer plates arranged therein between the at least one movable end plate (102) and the at least one fixed end plate (104), the roller cage (208) capable of rolling along a longitudinal direction (206) of the support bar (106), c h a r a c t e r i z e d i n t h a t the roller cage (208) comprising: - a roller holder (304), the roller holder (304) comprising a pair of half- axles (402, 404), wherein each half-axle of the pair of half-axles (402, 404) protrudes from the roller holder (304), and wherein the pair of half- axles (402, 404) is aligned along a common axis (314);

- a plurality of rollers (210, 212), the plurality of rollers (210, 212) being attached to the roller holder (304), wherein the plurality of rollers (210,

212) is movably connected to the support bar (106); and

- a pair of cradles (306, 308), wherein each cradle of the pair of cradles (306, 308) corresponds to a half-axle of the pair of half-axles (402, 404), and wherein each cradle of the pair of cradles (306, 308) comprising:

- a body portion (504), wherein the body portion (504) has a concave surface (502), the concave surface (502) resting on the corresponding half-axle of the pair of half-axles (402, 404), and wherein the body portion (504) is aligned along the longitudinal direction (206); and - an end portion (506), wherein the end portion (506) is attached to the at least one movable end plate (102).

2. A plate heat exchanger (100) according to claim 1 , wherein the support bar (106) comprises: -a carrying bar (204), wherein a first end of the carrying bar (204) is attachable to the at least one fixed end plate (104) and a second end of the carrying bar (204) is attachable to a support column (108); and -a hanging bar (202), wherein the hanging bar (202) is attached to at least a part of the carrying bar (204), and wherein the hanging bar (202) guides the movement of the plurality of rollers (210, 212).

3. A plate heat exchanger (100) according to claim 1 , wherein a thickness of the end portion (506) being substantially perpendicular to a thickness of the body portion (504).

4. A plate heat exchanger (100) according to claim 1 , wherein the end portion (506) comprises a plurality of recesses (316) at one or more edges of the end portion (506), wherein the plurality of recesses (316) facilitate attachment of the at least one movable end plate (102) to the end portion (506).

5. A plate heat exchanger (100) according to claim 1 , wherein a dimension of the body portion (504) along a first direction decreases gradually while moving outwards from the concave surface (502) along the longitudinal direction (206), and wherein the first direction lies along a surface of the body portion

(504) perpendicular to the common axis (314), and the first direction is mutually perpendicular to the longitudinal direction (206) and the common axis (314).

6. A plate heat exchanger (100) according to claim 1 , wherein each cradle of the pair of cradles (306, 308) is capable of executing rocker motion about the common axis (314).

7. A plate heat exchanger (100) according to claim 6, wherein the range of the rocker motion is from 3 to 7 degrees about the common axis (314).

8. A plate heat exchanger (100) according to claim 6, wherein the range of the rocker motion is from 4 to 5 degrees about the common axis (314).

9. A plate heat exchanger (100) according to claim 1 , wherein the at least one movable end plate (102) comprises a plurality of recesses, wherein at least one of the plurality of recesses is aligned along at least one of the plurality of recesses (316) on the end portion (506).

10. A plate heat exchanger (100) according to claim 8 further comprising a plurality of attachment means (302) to attach the roller cage (208) to the at least one movable end plate (102), wherein the plurality of attachment means (302) slides through the at least one of the plurality of recesses on the at least one movable end plate (102) aligned along the at least one of the plurality of recesses (316) on the end portion (506).

11. A plate heat exchanger (100) according to claim 1 , wherein the at least one movable end plate (102) comprises a cut-out, wherein the roller cage (208) is received in the cut-out of the at least one movable end plate (102).

12. A plate heat exchanger (100) according to claim 1 , wherein at least a part of the at least one movable end plate (102) is supported on a surface of the body portion (504), wherein the part of the at least one movable end plate (102) supported on the surface of the body portion (504) locks each cradle of the pair of cradles (306, 308) to the corresponding half-axle of the pair of half-axles (402, 404).

13. A plate heat exchanger (100) according to claim 11 , wherein the surface of the body portion (504) supporting at least a part of the at least one movable end plate (102) is curved or crowned.