Device for changing a flow direction through a heat exchanger and use thereof

A device for changing a flow direction through a heat exchanger, comprising a valve housing and a rotatable valve member arranged inside the valve housing. The valve housing comprises first and second ends and a center axis (B) extending between them. The device comprises a first port, a second port, a third port and a fourth port. The first end is provided with the first port, and the second end is provided with the third and fourth ports, wherein the valve member is rotatable between a first position and a second position and, in the first position, defines a conduit between the first port and the third port and, in the second position, defines a conduit between the first port and the fourth port. The valve member is rotatable around an axis of rotation offset from the center axis (B) and extending through the center of the first port, and the first port is angularly displaced 90° around the center axis (B) in relation to the third and fourth ports.

This application is a national phase of International Application No. PCT/SE2015/050892 filed Aug. 25, 2015 and published in the English language.

FIELD OF THE INVENTION

The present invention relates to a device for changing a flow direction through a heat exchanger. Heat exchangers, and particularly plate heat exchangers, are used within industry for a variety of heat exchange applications. Heat exchangers exchange heat between a first medium and a second medium. One of the mediums, such as the first medium, or both of the mediums can comprise undesired material, such as objects, particles, fibres or similar, which can clog the heat exchanger. Examples of such a first medium are sea water, waste water and any other type of fluid or liquid containing particles or fibres. Plate heat exchangers have a relatively small gap between adjacent heat exchanger plates, wherein such particles and fibres easily can be stuck and prevent the first medium to pass through the heat exchanger properly. For example, in many plate heat exchangers the gap between adjacent heat exchanger plates is 2-5 mm, wherein undesired material easily can be stuck to clog the heat exchanger. To prevent clogging of heat exchangers sometimes a filter can be used. However, a device reversing the flow direction of the first medium through the heat exchanger during short periods of time can be more efficient. When the undesired material inside the heat exchanger impairs the operation thereof the flow direction can be reversed for a period of time to cleanse the heat exchanger and remove the undesired material.

The present invention also relates to the use of a device for reversing the flow direction of one medium through a heat exchanger, e.g. to remove undesired material from it.

PRIOR ART

There are different types of devices for changing the flow direction through a heat exchanger in the prior art. One type of prior art device for changing the flow direction of one medium through a plate heat exchanger is disclosed in SE520124. The device according to SE520124 comprises a valve housing and a plurality of rotatable conduits arranged inside the valve housing, wherein the conduits are rotatable between different ports in the valve housing to change the flow direction.

A problem with devices for changing flow direction through heat exchangers according to the prior art is that they are relatively large and require a lot of space. Hence, they can be difficult to install in existing plants.

Another problem with such prior art devices is that they are heavy and sometime cannot be installed in existing plants due to the extra weight applied on foundations or similar.

Another problem with such prior art devices is that they are expensive.

SUMMARY OF THE INVENTION

An object of the present invention is to avoid problems of the prior art and provide a small, light and cost efficient device for changing the flow direction of one medium through a heat exchanger, which more easily can be installed in existing plants.

The present invention relates to a device for changing a flow direction through a heat exchanger, comprising a valve housing and a rotatable valve member arranged inside the valve housing, said valve housing comprising a first end, a second end and a centre axis extending between said first and second ends, wherein the device comprises a first port, a second port, a third port and a fourth port, said first end being provided with the first port, and said second end being provided with the third port and the fourth port, wherein the valve member is rotatable between a first position and a second position and, in the first position, defines a conduit between the first port and the third port and, in the second position, defines a conduit between the first port and the fourth port, characterised in that the valve member is rotatable around an axis of rotation offset from the centre axis, said axis of rotation extending through the centre of the first port, and the first port is angularly displaced 90° around the centre axis in relation to the third and fourth ports. The second port can be arranged in the first end of the valve housing. Alternatively, the second port can be arranged at another location, such as perpendicular to the first port and, for example, in a lower part of the valve housing. The first port or the first and second ports in the first end of the valve housing being displaced around the centre axis in combination with the axis of rotation being offset from the centre axis results in that space is made for an exterior actuator on the second end of the valve housing while using the surface of the valve housing ends for the ports efficiently. Hence, there is no need to make room for the actuator between the ports on the exterior surface of the valve housing. Instead the actuator can be arranged next to the ports, such as above, below or besides the ports, wherein a maximum area of each of the ends of the valve housing can be used for the ports and connecting flanges for connection to pipes to and from the device. Hence, according to the invention the area of the ends of the valve housing for the ports are used efficiently. Hence, the invention results in that the device can be reduced in size and weight compared to prior art devices, which saves material and cost and facilitate installation in existing plants as well as in new plants.

Further, the first port or first and second ports being angularly displaced 90° around the centre axis in relation to the third and fourth ports is believed to result an even symmetry and presumably favorable flow properties through the device and a structure which is easy to manufacture and which operates reliably and efficiently. The device can comprise the actuator for rotating the valve member around the axis of rotation. The actuator can be connected to the valve member through the shaft, said shaft extending through the second end of the valve housing, wherein the shaft is arranged coaxial with the axis of rotation. For example, the actuator is arranged entirely outside the valve housing and is not in contact with any medium of the heat exchanger, i.e. any fluid or liquid. The actuator can be mechanically and non-electronically connected to the valve member.

The valve member can comprise a first plate and a second plate forming a dividing wall for dividing the interior of the valve housing into two compartments to reduce pressure drop of the medium flowing through the device. There are two flow paths through the valve housing, i.e. one through the conduit of the valve member and the other outside the valve member inside the valve housing. There can be a considerable pressure drop for the flow through the valve housing outside the valve member. By dividing the interior of the valve housing by means of the first and second plates attached to the valve member the cross section of the flow path through the valve housing can be reduced, wherein the pressure drop is reduced.

The centres of the first and second ports can be arranged on a first imaginary line perpendicular to and crossing the centre axis of the valve housing, and the centres of the third and fourth ports can be arranged on a second imaginary line perpendicular to and crossing the centre axis of the valve housing. In this way the surface of the ends of the valve housing can be used efficiently. The first imaginary line can be perpendicular to the second imaginary line. For example, the first imaginary line can be a vertical line and the second imaginary line can be a horizontal line when the centre axis extends horizontally. Hence, the first port can be an inlet port and the second port can be an outlet port and the first port can be arranged above the second port. Undesired material in the medium flowing through the valve housing outside the conduit of the valve member tend to sink to the bottom of the valve housing, wherein it can be cleansed by the flow and follow the medium out from the valve housing through the lower outlet formed by the second port. The third and fourth ports can be arranged side by side and can be displaced in the lateral direction in relation to each other.

An exterior side of the valve housing ends can be provided with threaded holes, for example, being evenly distributed around the ports and, optionally, having a hole circle being concentric with the ports, respectively. The threaded holes are arranged for receiving bolts or screws to fasten pipes directly to the device without the use of any intermediate connection pipes. Further, connecting flanges can be arranged directly on the valve housing ends. For example, connecting flanges can be fastened to the valve housing ends by screws.

The connections on large pipes are usually arranged as connecting flanges, and prior art devices for reversing flow direction through heat exchangers are generally provided with connection pipes having connecting flanges, which are expensive. The ends of the valve housing can be arranged in carbon steel to keep the cost down, while the projecting connection pipes according to prior art must be corrosive resistant as they are in contact with the fluid flowing through the device. Sometimes it is not suitable to weld such prior art connection pipes to the ends of the valve housing, e.g. as it can be different materials, wherein the connection pipes must be fastened by means of bolted joints. A typical prior art joint can comprise a flange of the same size and material as the as the pipe, said flange being welded to the pipe, the joint further comprising a flange of carbon steel outside the welded flange and a plurality of bolts being fastened to holes in the end of the valve housing. The connection pipe extends through the port in the end of the valve housing and is welded to a plate on the interior of the end of the valve housing. Hence, according to prior art the connection pipe is permanently fixed to the valve housing and cannot be removed by removing the bolts.

According to the present invention, however, two standard type connecting flanges of pipes can be placed next to each other directly on the ends of the valve housing and then fastened to the ends by means of bolts screwed into the holes around the ports, wherein a less expensive and less complicated structure with fewer parts is provided compared to prior art devices of this type.

The present invention also relates to a use of the device as described above for reversing a flow direction of one medium through a heat exchanger. The flow direction can be reversed to remove undesired material, such as particles, fibres or debris, from the heat exchanger. The flow direction can be reversed periodically, on demand or automatically when required, such as by use of appropriate sensors.

Further characteristics and advantages of the present invention will become apparent from the description of the embodiments below, the appended drawings and the dependent claims.

DETAILED DESCRIPTION OF EMBODIMENTS

Referring toFIG. 1a device1for changing a flow direction of a medium through a heat exchanger2, such as a plate heat exchanger, is disclosed according to one embodiment example. InFIG. 1the device1is connected to a first pipe3for conducting a medium, such as a first medium, to or from the device1. In the illustrated embodiment the first pipe3is connected to a first main pipe4for transporting the first medium to or from the first pipe3. For example, the first pipe3is arranged for conducting the first medium to the device1. The device1is further connected to a second pipe5for conducting the first medium to or from the device1. In the illustrated embodiment the second pipe is connected to a second main pipe6for transporting the first medium to or from the second pipe5. For example, the second pipe5is arranged for conducting the first medium away from the device1. The device1is further connected to a third pipe3(5) and a fourth pipe5(3) connecting the device with the heat exchanger2. The device1is connected to one circuit of the heat exchanger2for one medium, wherein pipes of the second circuit for conducting a second medium to and from the heat exchanger2are not illustrated in the drawings.

According to the illustrated embodiment example, the first medium is conducted from the first main pipe4to the device1through the first pipe3, wherein the first medium is conducted through the device1and into the heat exchanger2through the third pipe3(5). For example, the first medium is conducted into a bottom part of the heat exchanger2. After passing through the heat exchanger2, the first medium is conducted out from the heat exchanger2and to the device1through the fourth pipe5(3), and then to the second main pipe6through the second pipe5. For example, the first medium is conducted out from the heat exchanger through a top part thereof. An example of normal flow operation is illustrated by means of the solid arrows inFIG. 1. When the flow direction of the first medium through the heat exchanger is reversed by means of the device1, the first medium is conducted from the main pipe4, through the first pipe3to the device1and then through the fourth pipe5(3) into the heat exchanger2, wherein the first medium is conducted out from the heat exchanger2to the device1through the third pipe3(5) and further to the second main pipe6through the second pipe5. An example of reversed flow operation from the heat exchanger2to the device1is illustrated by means of broken arrows inFIG. 1. For example, during reversed flow, the first medium is conducted into the heat exchanger2through the top part thereof, wherein the first medium is conducted out from the heat exchanger2through the bottom part thereof. Hence, by means of the device1the flow direction of the first medium through the heat exchanger2is reversed and then changed back to the original flow direction. For example, the flow direction is changed periodically or when required.

With reference toFIG. 2the device1comprises a valve housing7having a second end8and a first end9. For example, the valve housing7is formed as a cylinder, e.g. having circular cross section. The first end9is arranged opposite the second end8. For example, the first and second ends9,8are substantially circular. In the illustrated embodiment the device comprises lining rings10-13for engagement with the pipes3(5),5(3),3,5or connecting flanges thereof. Lining ring11is illustrated within parenthesis as it is hidden behind lining ring10inFIG. 2. The first and second ends9,8are, for example, connected to each other by a plurality of conventional bolt connections14, so that a central casing of the valve housing7is connected to the first and second ends9,8in a pressure tight connection. For example, the valve housing7are made of metal, such as a non-magnetic metal or alloy, such as a nickel steel alloy or titanium. Alternatively, the first and second ends9,8are made of carbon steel.

An actuator15for controlling the flow direction is arranged on the valve housing7. For example, the actuator15is arranged on the exterior of the valve housing7, such as on the exterior of the first or second end9,8thereof. For example, the actuator15is arranged on the second end8of the valve housing7, such as at an upper part thereof. The actuator15comprises motorized and/or manual devices for operating the device1, which are arranged outside the valve housing7. For example, the actuator15is made of aluminium or carbon steel.

With reference toFIG. 3the device1is illustrated in the direction of the arrow A inFIG. 2, such as from above, wherein the lining ring11is visible. The valve housing7has a centre axis represented by the line B inFIG. 3. The centre axis B extends between the first and second ends9,8of the valve housing7. The centre axis B extends through the centre of the valve housing7. For example, the centre axis B extends from a centre point of the first end9to a centre point of the second end8.

With reference toFIG. 4a valve member16is arranged within the valve housing7between the first and second ends9,8thereof. The valve member16forms a conduit for the first medium through the valve housing7. The valve member16is rotatable and can be rotated around an axis of rotation17. The valve member16can be rotated between a first and a second position. For example, the valve member16can be rotated 90° around the axis of rotation17. The rotation of the valve member16is provided by the actuator15, the actuator15being connected to the shaft18extending through the second end8of the valve housing7and is connected to a hub19of the valve member16. The valve member16is guided by a combined bearing and sealing in ring20. For example the ring20is connected to the valve member16through a plate. An o-ring21forms a sealing around the shaft18which is mounted in a bearing22. InFIGS. 4-6the valve member16is in a middle position, i.e. between the first and second positions, such as 45° from the first and second positions.

With reference toFIG. 5the second end8of the valve housing7according to the embodiment ofFIG. 2is illustrated. By means of the arrows inFIG. 5the rotation of the valve member16is illustrated between the first and second positions E, F along the curved line G. The first and second positions E, F are, for example, end positions and coincide with the centre of the third and fourth pipes3(5),5(3), respectively, when said pipes3(5),5(3) are connected to the device1. During operation the valve member16is in one of the first and second positions, wherein the position of the valve member16is changed for reversing the flow direction through the heat exchanger2. In the illustrated embodiment the valve member16is in position E during normal operation and in position F during reversed flow operation. The point H indicate the centre of an outlet orifice of the valve member16.

With reference toFIG. 6the first end9of the valve housing7according to the embodiment ofFIG. 2is illustrated.

FIGS. 7 and 8illustrate the valve member16according to one embodiment. The valve member16comprises a curved conduit23, such as a pipe, extending between the first and second ends9,8of the valve housing7. Hence, the conduit23has a first end at the first end9of the valve housing7and a second end at the second end8of the valve housing7. Alternatively, the valve member16comprises a straight and inclined conduit, such as a straight pipe having bevelled end portions forming an oblique cylinder shape. The first end portion of the conduit23is provided with a combined bearing and sealing24, wherein the second end portion of the conduit23is provided with a sealing25. For example, the material of the combined bearing and sealing24and the sealing25has low friction against the interior surface of the ends9,8of the valve housing7, so that the torque for rotating the valve member16can be low.

According to the illustrated embodiment the valve member16comprises a first plate26and a second plate27dividing the interior of the valve housing7to reduce the cross section of the flow through the valve housing7so as to reduce the pressure drop in the device1. For example, the first plate26and the second plate27are arranged in a common plane and extend from opposite sides of the conduit23, such as a top side and a bottom side, respectively. For example, the first and second plates26,27are fixed to the conduit23and rotate along with the conduit23when the valve member16is rotated. The first and second plates26,27extend along the flow direction through the valve housing7outside the conduit23of the valve member16. For example, the first and second plates26,27are arranged in a plane along which the axis of rotation17extends. For example, the axis of rotation17is horizontal.

In the illustrated embodiment a connecting plate28connects the hub19with the second end of the conduit23. The connecting plate28is fixed to the conduit23and the shaft18to the hub19, wherein the valve member7is rotated when the shaft18is rotated by means of the actuator15. The connecting plate28extends, for example, perpendicular or at an angle to the shaft18. For example, the second end of the conduit23is arranged below the hub19. For example, the connecting plate28also supports the sealing25.

Referring back toFIGS. 4-6the valve housing7is provided with a first port29, a second port30, a third port31and a fourth port32. The ports29-32are arranged for connection to the pipes3,5,3(5),5(3), respectively, so that the medium is conducted to and from the device1through the ports29-32. For example, the first pipe3is arranged for connection to the first port29, the second pipe5is arranged for connection to the second port30, the third pipe3(5) is arranged for connection to the third port31and the fourth pipe5(3) is arranged for connection to the fourth port (32). The lining rings10-13are arranged around the ports31,32,29,30, respectively, for engagement with corresponding connection flanges of the pipes3(5),5(3),3,5. In the illustrated embodiment, the lining rings10-13are fastened to port linings extending into the ports31,32,29,30, for example by welding. For example, the lining rings10-13project less than 30 mm, less than 20 mm or less than 10 mm in the axial direction from the exterior surface of the first and second ends9,8.

The first and the second ports29,30are arranged in the first end9of the valve housing7, wherein the third and fourth ports31,32are arranged in the second end8thereof. Alternatively, the second port30is arranged at any other suitable location on the valve housing7, such as in the lower part thereof. For example, the second port30is arranged perpendicular to the first port29. The centre of the first port29is arranged at a distance from the centre axis B of the valve housing7and the centre of the second port30is arranged at a distance from the centre axis B on the opposite side thereof, so that the first and second ports29,30are displaced in relation to the centre axis B. For example, the distance between the centre of the first port29and the centre axis B is equal to the distance between the centre of the second port30and the centre axis B. For example, the first port29is an inlet port, wherein the second port30is an outlet port. For example, the first port29is arranged above the second port30. For example, the centre of the first port29and the second port30are arranged on a first imaginary line, such as a vertical line, being perpendicular to the centre axis B. For example, the first imaginary line intersects both the centre axis B and the axis of rotation17. The centre of the third port31is arranged at a distance from the centre axis B of the valve housing7and the centre of the fourth port32is arranged at a distance from the centre axis B on the opposite side thereof, so that the third and fourth ports31,32are displaced in relation to the centre axis B. For example, the distance between the centre of the third port31and the centre axis B is equal to the distance between the fourth port32and the centre axis B. For example, the centre of third port31and the fourth port32are arranged on a second imaginary line being perpendicular to the centre axis B and the first imaginary line on which the first and second ports29,30are arranged. The first and second ports29,30are angularly displaced 90° around the centre axis B in relation to the third and fourth ports31,32. For example, the second imaginary line on which the centre of the third and fourth ports31,32are arranged is a horizontal line.

The axis of rotation17coincides with the centre of the first port29and, e.g., extends in parallel to the centre axis B. Hence, the remaining ports30-32are offset to the axis of rotation17. The centre of the third port31and the fourth port32are arranged with the same distance to the axis of rotation17. Hence, the third and fourth ports31,32are arranged on an imaginary circle around the axis of rotation17, which imaginary circle is arranged perpendicular to the axis of rotation17, to interact with the second end of the conduit23when the valve member16is rotated between the first and second positions. The curve G ofFIG. 5represents a part of said imaginary circle.

The first end of the conduit23of the valve member16is connected to the first port29and the second end of the conduit23is displaceable between the third port31and the fourth port32. Hence the valve member16is rotatable between its first position, in which the first medium is conducted from the first port29to the third port31, and its second position, in which the first medium is conducted from the first port29to the fourth port32, for example, for reversed flow through the heat exchanger2.

Referring back toFIG. 5the arrows illustrate the rotation of the valve member16between the first and second positions E, F along the curved line G, wherein the first and second positions E, F coincide with the third and fourth ports31,32, respectively. During operation the valve member16is in one of the first and second positions E, F to allow the medium to pass from the first port29to the third port31or the fourth port32. The position of the valve member16is changed, for example from the third port31to the fourth port32or vice versa, for reversing the flow direction through the heat exchanger2.

It is to be understood that the conduit23of the valve member16is constantly connected to one port of one of the ends9,8of the valve housing7. In the illustrated embodiment that is the first port29. However, the conduit23of the valve member16can be constantly connected to any of the ports29-32, provided that said port is arranged in one of the ends9,8, and then rotated between the two ports of the opposite end of the valve housing7.

With reference particularly toFIGS. 5 and 6the first and second ends9,8of the valve housing7comprise threaded holes33. The holes33are arranged on an exterior side of the first and second ends9,8to receive bolts for connecting the pipes3,5,3(5),5(3) to the device1. Hence, the holes33are arranged for forming a bolt joint with a connecting flange of the pipes3,5,3(5),5(3) to be connected with the device1. For example, the holes33are distributed around the ports,29-32, respectively, such as around the lining ring12,13,10,11around each of the ports29-32.

FIGS. 9 and 10is a comparison between the device1according to the invention, which is illustrated inFIG. 10, with a prior art device according to SE520124.