EP2433077B1

EP2433077B1 - A heat exchanger

Info

Publication number: EP2433077B1
Application number: EP10720710.2A
Authority: EP
Inventors: Heri Schwartz Jacobsen
Original assignee: Sp/f Defined Energy
Current assignee: Sp/f Defined Energy
Priority date: 2009-05-20
Filing date: 2010-05-20
Publication date: 2018-10-24
Anticipated expiration: 2030-05-20
Also published as: ES2706381T3; DK3517872T3; EP2433077A2; ES2852375T3; EP3517872B1; PL2433077T3; EP3517872A1; DK2433077T3; WO2010133230A2; PL3517872T3; WO2010133230A3; LT3517872T; LT2433077T

Description

Field of the invention

The present invention relates to a heat exchanger as defined in the preamble of claim 1.

Background of the invention

Substantial amounts of energy are used for heating up various fluids to be used in a household or for industrial purposes. This heat energy is wasted if the heated fluid is discharged to a drain directly after being used.
Heat exchanging equipment is widely used for changing or maintaining the temperatures of machinery, buildings, components and the like. The basic principle of most heat exchangers is to transfer heat between two or more fluids. The heat transfer takes place mainly due to the temperature gradient, as the respective fluids are moving towards thermal equilibrium.
US 4,998,464 discloses a heat exchange device that can be used for continuously cooling or heating a slurry of food. The device comprises several vertically spaced heat transfer trays in alignment with each other and each having an opening extending there through. The food slurry has to be pushed or scraped by slowly moving scraper members to each opening, where it can fall by force of gravity to an adjacent lower tray. Due to the great number of moving parts, such a device needs to be overhauled frequently, resulting in undesirable operation stops. In addition, said moving parts have a negative impact on the overall energy consumption of the device. Furthermore, the large number of components renders cleaning of the device time-consuming and complicated. Moreover, the general design of the device, in particular its structural properties, renders the device unsuitable for processing other materials than the fairly viscous slurry of food.
US3,770,252 A discloses another heat exchange device according tot he preamble of claim 1.

Summary of the invention

In view of the above, an objective of the present invention is to provide a heat exchanger capable of more efficiently transporting a flowable material through it.
In view of at least this object, the heat exchanger is characterized by the features according to the characterizing part of claim 1.
In this context, radial direction is construed as a direction of motion toward or away from an axis of rotational movement, wherein said axis passes through the drain and is substantially coincident with the direction of gravity, whereas tangential direction is construed as a direction perpendicular to said radial direction. The velocity component in the tangential direction renders possible the rotation of the fast flowable material around said axis of rotation.
By providing the heat exchanger with at least two consecutive, vertically spaced and receiving receptacles in fluid communication, a multiple recovery of the heat contained in the first flowing material takes place. The total recovered heat is then an aggregate of the particular amounts of heat extracted in the respective recovery step. At first, a portion of the heat contained in the first flowable material may be recovered during heat transfer between said flowable material and said first means for absorbing heat being part of the first receiving receptacle. The first flowable material should in its broadest sense be construed as a fluid. However, normally said material would be a liquid. As an alternative, said liquid may contain lumps of solid matter. The heat transfer is ensured since said first flowable material and said first means for absorbing heat are brought in direct contact. Said first flowable material, containing residual heat, may thereafter be discharged from the first receiving receptacle through the first drain and may subsequently be brought in direct contact with said second means for absorbing heat being part of the further receiving receptacle. Further heat transfer may thereby be ensured. An additional portion of heat energy still contained in the first flowable material may thereby be recovered. By applying a series of consecutive, vertically spaced, fluidly communicating receiving receptacles, an increased portion of the heat energy contained in the first flowable material may be recovered using respective means for absorbing heat as intermediary. This may contribute to improved overall efficiency of the heat exchanger.
According to the characterizing part of claim 1, the contact between the first flowable material and the bottom part of the further receiving receptacle comes about in a controlled manner and takes place at the appropriate section of the bottom part of the further receiving receptacle. An enhanced heat transfer, that positively affects efficiency of the device, is thereby obtained. This is accomplished without providing the device with moving parts. Instead, structural design of the device renders possible to employ gravitational and centripetal force in order to move the flowable material, thereby saving energy and simplifying the device.
Said contact between the first flowable material and the bottom of the further receiving receptacle is, as stated above, achieved without providing the device with moving parts. This may significantly reduce maintenance needs and frequency of operation stops. Consequently, a more cost-efficient device may be obtained. In addition, the reduction of the number of moving parts may positively affect overall energy consumption of the device.
The reduced number of components used may simplify the cleaning of the device and reduce the duration thereof. Downtime of the device is hereby reduced, contributing positively to its overall efficiency.
Moreover, the field of use of the device is broad since flowable materials such as viscous and non-viscous liquids, optionally containing lumps of solid matter, may be processed therein.
In embodiments useful in connection with the invention, the first flowable material is discharged in a controlled manner from the first receiving receptacle and subsequently brought in direct contact with the desired section of the bottom part of the further receiving receptacle. This turns out to be advantageous as direct draining of the first flowable material may in this way be avoided. In addition, by suitably shaping and positioning said conduit, it may be ensured that contact between the first flowable material and the bottom of the further receiving receptacle, comprising second means for absorbing heat, comes about in a controlled manner and takes place at the appropriate section of the bottom part of the further receiving receptacle. An enhanced heat transfer, that positively affects efficiency of the device, may thereby by obtained. As stated above, this is achieved without providing the device with moving parts. Instead, structural design of the device renders possible to employ gravitational and centripetal force in order to recover energy.
According to a preferred embodiment, said first drain for discharging said first flowable material is positioned substantially in the centre of said bottom part, and is in communication with said means for directing said first flowable material onto the second bottom part, wherein said means comprise a guide, such as a channel or a pipe, for transporting said first flowable material, said guide being positioned under said first receiving receptacle, and extending at first substantially radially from the centre of said bottom part towards or beyond said second wall of said further receptacle, and, changing thereupon, when being close to said second wall, its direction of extension to a substantially tangential direction, such that the flowable material is introduced onto the second bottom part near said second wall with a velocity component in a tangential direction.
According to a preferred embodiment, at least one of said first or second means for absorbing heat may comprise a spirally wound tube. Consequently, due to the intrinsic properties of said tube, energy losses attributable to the friction between the flowing fluid contained in said tube and its inner walls may be reduced. In addition, first flowing material may be brought in direct contact with an increased part of the outer surface of the tube. This imparts improved overall efficiency of the heat exchanger.
According to another preferred embodiment, said first or second bottom part of the first or further receiving receptacle may be configured in such a manner that the first flowable material is at least partially prevented from running directly into the first or second drain. Thus, the time period during which said first flowable material is in direct contact with said bottom parts may be significantly increased. As a consequence, a larger amount of heat contained in the first flowable material may be transferred improving thereby overall efficiency of the heat exchanger.
According to the invention, at least a portion of the first or second bottom part of the first or further receiving receptacle may be sloping downwardly towards the first or second drain, respectively, so as to direct the first flowable material into a respective one of the first or second drain. In this way, the use of complex guiding means in order to control the draining of said first flowable material may be made superfluous. As an advantage, a simplified heat exchanger design may be obtained.
According to another preferred embodiment, further receiving receptacle may have a connection means adapted to receive said first receiving receptacle. Said connection means may enable interconnection of a plurality of fluidly communicating receiving receptacles. As a consequence, multiple recovery of the heat contained in the first flowing material may take place. The overall efficiency of the heat exchanger may thereby be improved.
According to another preferred embodiment, said heat exchanger may be arranged in a casing, the casing having an inlet tube adapted to direct the first flowable material onto at least a portion of the first bottom part of the first receiving receptacle in a direction not coinciding with the direct path towards the first drain. Consequently, the heat exchanger may be protected from undesirable external influences, yielding a sturdier heat exchanger. Furthermore, by suitably directing the first flowable material it may be ensured that the first flowable material is brought in direct contact with the desired section of the bottom part of the first receiving receptacle.
Other objectives, features and advantages of the present invention will appear from the following detailed disclosure, from the attached claims as well as from the drawings.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the [element, device, component, means, step, etc]" are to be interpreted openly as referring to at least one instance of said element, device, component, means, step, etc., unless explicitly stated otherwise.

Brief description of the drawings

The above, as well as additional objects, features and advantages of the present invention, will be better understood through the following illustrative and non-limiting detailed description of preferred embodiments of the present invention, with reference to the appended drawings, where the same reference numerals will be used for similar elements, wherein:

Fig. 1 is a schematic longitudinal cross-sectional view of a casing enclosing a heat exchanger according to a first embodiment of the present invention.
Fig. 2 is a close-up of said longitudinal cross-sectional front view showing a heat exchanger 1 comprising a series of four subsequent, vertically spaced and fluidly communicating receiving receptacles according to the first embodiment of the present invention.
Fig. 3a is a perspective top view of a receiving receptacle according to another embodiment of the present invention.
Fig. 3b is a perspective bottom view of the receiving receptacle shown in Fig. 3a.

Detailed description

Fig. 1 is a schematic longitudinal cross-sectional view of a casing 18 enclosing a heat exchanger 1 according to a first embodiment of the present invention. The heat exchanger 1 of the present invention may be an integral part of a larger energy recovery system. Such a system may, for instance, be used onboard ships and in residential buildings.
The heat exchanger 1 comprises a series of consecutive, vertically spaced and fluidly communicating receiving receptacles 2 arranged at mid-section of the casing 18. Each receptacle comprises a bottom part 5 and a wall 4 as well as a cavity 3, delimited by said bottom part 5 and said wall 4, and is, furthermore, provided with a directing means 22 for guiding the first flowable material in the desired direction. The positioning, shape and number of the receiving receptacles 2 may vary substantially depending on the field of application. The first flowable material is normally a liquid, optionally containing lumps of solid matter. The first flowable material may, for example, be a waste hot water generated in a household or a fluid by-product of various industrial processes. A flowable material inlet tube 19 extends through an aperture 16 in a top section of the casing 18. A casing outlet 21 is arranged at a lowermost section of the casing 18.
The first flowable material is introduced into the casing 18 by means of the flowable material inlet tube 19 and deposited in the peripheral section of the bottom part 5. Heat transfer occurs when first flowable material is brought in contact with the bottom part 5. After being introduced into the casing 18, the first flowable material cascades down, due to the gravitational force, from the uppermost receiving receptacle 8 via directing means 22 for guiding the first flowable material in the desired direction as well as intermediate receiving receptacles. Said directing means 22 ensure that the first flowable material is discharged in a controlled manner and deposited at the desired section of the subsequent receiving receptacle. Once said first flowable material reaches the lowermost receiving receptacle 30 and the heat exchange has taken place, the material is discharged there from by means of said directing means 22, whereupon the first flowable material is evacuated from the casing 18 via the casing outlet 21. The operation of the heat exchanger 1 will be more thoroughly described below, in conjunction with Fig. 2.
The present invention enables, by suitably modifying certain important features of the conventional heat exchanger, such as fluids being confined in narrow flow channels, heat exchange even when liquid flowable material contains lumps of solid matter. Advantageously, clogging of the heat exchanger by said lumps of solid matter, inevitable in conventional heat exchangers, may be prevented.
By enclosing the heat exchanger 1 in the casing 18, said heat exchanger 1 may be protected from undesirable external influences, thus yielding a sturdier heat exchanger 1.
Fig. 2 is a close-up of the longitudinal cross-sectional front view showing a heat exchanger 1 comprising a series of four consecutive, vertically spaced and fluidly communicating receiving receptacles 2 according to the first embodiment of the present invention. In the following, only two uppermost receiving receptacles 8, 10 and their interaction will be described in order to illustrate the structure and the operation principle of the system described generally in conjunction with Fig. 1.
The heat exchanger 1 comprises an upper or first receiving receptacle 8 and a lower or second receiving receptacle 10 positioned directly below said first receiving receptacle 8. Said receptacles 8, 10 are connected by connection means 20 which will be more thoroughly discussed in conjunction with Fig. 3a. Each receptacle comprises a bottom part 5, 13 being essentially constituted by means for absorbing heat 6 in form of a spirally wound tube, a wall 4, 12 made of thermally insulating material, such as natural or synthetic rubber or polyurethane, as well as a cavity 3, 11 delimited by said bottom part 5, 13 and said wall 4, 12. A gap 25 is provided between each two adjacent windings of the spirally wound tube. Said gap 25 will, like the above-mentioned connection means 20, be more thoroughly described in conjunction with Fig. 3a. Each receptacle is furthermore provided with a drain 9, 17 for discharging first flowable material. Normally, the drain 9, 17 is positioned in the central section of the bottom part 5, 13. Said drain 9, 17 falls into directing means 22 for guiding the first flowable material in the desired direction.
The bottom part 5, 13 may be flat, but it is advantageous to arrange said bottom part to be essentially bowl- or funnel-shaped, i.e. to uniformly slope downwardly from the peripheral section of the bottom part 5, 13 towards the drain 9, 17. This arrangement dispenses with use of complex guiding means in order to control draining of said first flowable material. This embodiment is particularly suitable for applications where first flowable material is a high-density or particle-rich waste liquid.
The first flowable material is introduced into the first receiving receptacle 8 using a flowable material inlet tube (not shown in Fig. 2) in a manner described in conjunction with Fig. 1. Typically, the first flowable material is directed towards the peripheral section of the bottom part 5 of the first receiving receptacle 8. A conductive heat transfer occurs when first flowable material is brought in contact with the bottom part 5. The inherent kinetic energy of the first flowable material combined with its direction of movement, conferred by said flowable material inlet tube as well as a physical obstacle created by the wall 4 permit a substantially circular flow of the first flowable material in the cavity 3, i.e. a whirl-like motion with an ever decreasing radius of movement. Eventually, said material reaches the central section of the bottom part 5 where the drain 9 is arranged. Subsequently, said first flowable material exits the first receiving receptacle 8. The first flowable material then flows, due to the gravitational force, via said directing means 22 to the second receiving receptacle 10. This is repeated, as described in conjunction with Fig. 1, until said first flowable material reaches the drain 19 of the last receiving receptacle 30. The first flowable material is thereupon discharged from the last receiving receptacle 30 using said directing means 22. Subsequently, the first flowable material is evacuated from the casing 18 via the casing outlet that is shown in Fig. 1.
By providing the wall of the receiving receptacle in thermally insulating material it may be achieved that conductive heat energy losses to the surroundings may be reduced, improving thereby the efficiency level of the heat exchanger.
Fig. 3a is a perspective top view of a receiving receptacle 2 according to another embodiment of the present invention.
As previously stated, in conjunction with Fig. 2, the receiving receptacle 2 comprises a cavity 3 essentially delimited by a wall 4 and a bottom part 5, said cavity being arranged for receiving first flowable material. Said bottom part 5 is constituted by means for absorbing heat 6 in form of a spirally wound tube 26 made of a material having high thermal conductivity, such as copper, aluminium or nickel. A gap 25 that may be viewed in Fig. 2 is provided between each two adjacent windings of the spirally wound tube 26. The purpose of the gap 25 is to increase time period during which said first flowable material is in direct contact with means for absorbing heat 6. This embodiment is especially suitable for the applications where the first flowable material is scarce and has high temperature. A drain 9 is essentially delimited by said means for absorbing heat 6 and positioned in the central section of the bottom part 5. Second flowable material is introduced into means for absorbing heat 6 via an inlet 7. Said second flowable material may be any suitable fluid, such as water or air. It subsequently leaves said means for absorbing heat 6 via an outlet 8. A suitably sized pump (not shown) propels said second flowable material. Connection means 20 extends circumferentially along an upper edge of the receiving receptacle 2. Said connection means 20 is a mechanical shoulder adapted to engage firmly with the adequately shaped outer peripheral section of the bottom part of another receiving receptacle, enabling thereby stacking of receiving receptacles on top of each other. In order to provide additional stability to the coupled pair of the receiving receptacles, said connection means 20 may be provided with locking means. Moreover, a radial direction r that is to be construed as a direction of motion toward or away from an axis of rotational movement 28, wherein said axis 28 passes through the drain 9 and is substantially coincident with the direction of gravity, and a tangential direction t that is to be construed as a direction perpendicular to said radial direction r, are shown.
It may be envisaged to interchange the inlet 7 and the outlet 8, reversing thereby flow direction of the second flowing material. By alternating the flow direction of the second flowing material, a concurrent as well as counter current heat exchanger may be achieved.
Second flowable material is introduced into means for absorbing heat 6 via an inlet 7 and is circulated in said means, starting from the central section of the bottom part 5 and flowing outwards to its peripheral section, corresponding to the way the first means for absorbing heat 6 is arranged. As explained above, means for absorbing heat 6 absorbs the heat contained in the first flowable material and convectively transfers said heat to the second flowable material.
Now, turning to Fig. 3b that illustrates a perspective bottom view of the receiving receptacle 2 shown in Fig. 3a.
As it may be seen, directing means 22 for guiding the first flowable material in the desired direction is positioned adjacent to and below said receiving receptacle 2. Said means 22 has a first end 23 and a second end 24. The first end 23 is positioned immediately downstream of the drain orifice (not shown in Fig. 3b) and the second end 24 is a free end that extends to the peripheral section of the receiving receptacle 2.
Directing means 22 for guiding the first flowable material in the desired direction are a downwardly sloping guiding conduit having substantially circular, elliptical or quadrangular cross-section at its free end 24. Upon being discharged from the receiving receptacle 2, first flowing material flows into the first end 23 of the guiding conduit 22. It is there from guided to its second, free end 24 and is subsequently discharged there from. Said guiding conduit 22, by way of example a channel or a pipe, extends at first substantially radially from the centre of said bottom part 5 towards or beyond the wall 4 of the receptacle 2, changes thereupon, when being close to the wall 4, its direction of extension to a substantially tangential direction t, such that the flowable material is introduced onto a second bottom part (not shown) near a second wall (not shown) with a velocity component in the tangential direction. The velocity component in the tangential direction renders possible the rotation of the fast flowable material around the axis of rotation 28 shown in fig. 3a.
The size and the shape of the first and the second end of said directing means may vary depending on the application field of the heat exchanger. By way of example, the directing means provided with quadrangular cross-section at the free end is particularly suitable for applications where first flowable material is a high-density waste liquid or a particle-rich liquid by-product of various industrial processes.
The direction of circulation of the first flowable material discharged from the receiving receptacle 2 may be defined by suitably configuring said directing means 22 for guiding the first flowable material in the desired direction. Similarly to what has been previously described in conjunction with Fig. 3a, a concurrent or counter current heat exchanger may hereby be achieved.
The invention has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims.

Claims

A heat exchanger (1) for recovering heat contained in a first flowable material, said heat exchanger (1) comprising
a first receiving receptacle (2) having a first cavity (3) for receiving said first flowable material, said first cavity (3) being defined by a first wall (4) and a first bottom part (5), and having a first drain (9) in said bottom part (5) for discharging said first flowable material, and
a first means for absorbing heat (6) having a first inlet (7) for receiving a second flowable material to be heated by said first flowable material and a first outlet (8) for discharging said second flowable mate-rial heated by said first flowable material,
said first means for absorbing heat (6) being arranged to form at least a part of said first bottom part (5) of said first receiving receptacle (2),
wherein said heat exchanger (1) comprises at least one further receiving receptacle (10) positioned in series with said first receiving receptacle (2) and having a second cavity (11) for receiving said first flow-able material, said second cavity (11) being defined by a second wall (12) and a second bottom part (13), and having a second drain (17) in said second bottom part (13) for discharging said first flowable material; and
a second means for absorbing heat (14) having a second inlet for receiving a second flowable material to be heated by said first (25) flowable material and a second outlet (16) for discharging said second flowable material heated by said first flowable material,
said second means for absorbing heat (14) being arranged to form at least a part of said second bottom part (13) of said further receiving receptacle (10),
said first drain (9) of said first receiving receptacle (2) is in communication with a means (22) for directing said first flowable material onto the second bottom part (13),
characterized in that
said means (22) for directing said first flowable material is a downwardly sloping guiding conduit having substantially circular, elliptical or quadrangular cross-section at its free end (24),
said means (22) is adapted to guide the flowable material by means of gravity in a radial direction (r) towards or beyond said second wall (12) of said further receptacle (10), and in a tangential direction (t) such that the flowable material is introduced onto the second bottom part (13) near said second wall (12) with a velocity component in a tangential direction (t).
A heat exchanger (1) according to claim 1, wherein said first drain (9) for discharging said first flowable material is positioned substantially in the centre of said bottom part (5), and is in communication with said means (22) for directing said first flowable material onto the second bottom part (13), wherein said means (22) comprise a guide, such as a channel or a pipe, for transporting said first flowable material, said guide being positioned under said first receiving receptacle (2), and extending at first substantially radially (r) from the centre of said bottom part (5) towards or beyond said second wall (12) of said further receptacle (10), and, changing thereupon, when being close to said second wall (12), its direction of extension to a substantially tangential direction (t), such that the flowable material is introduced onto the second bottom part (13) near said second wall (12) with a velocity component in a tangential direction (t).
A heat exchanger (1) according to any of the preceding claims, wherein at least one of said first means for absorbing heat (6) or said second means for absorbing heat (14) comprises a spirally wound tube.
A heat exchanger (1) according to any of the preceding claims, wherein said first or second bottom part (5, 13) of said first or further receiving receptacle (2, 10) is configured in such a manner that said first flowable material is at least partially prevented from running directly into said first or second drain (9, 17).
A heat exchanger (1) according to any of the preceding claims, wherein at least a portion of said first or second bottom part (5, 13) of said first or least one further receiving receptacle (2, 10) is sloping downwardly towards said first or second drain (9, 17), respectively, so as to direct said first flowable material into a respective one of said first or second drain (9, 17).
A heat exchanger (1) according to any of the preceding claims, wherein said further receiving receptacle (10) has a connection means (20) adapted to receive said first receiving receptacle (2).
A heat exchanger (1) according to any of the preceding claims, wherein said heat exchanger (1) is arrangable in a casing (18),
said casing (18) having an inlet tube (19) adapted to direct said first flowable material onto at least a portion of said first bottom part (5) of said first receiving receptacle (2) in a direction not coinciding with the direct path towards the first drain (9).