Tube bundle heat exchanger including a component / built-in element formed by a deflecting surface and a guiding section

Abstract

The present invention relates to a tube bundle heat exchanger which comprises built-in elements formed by a deflection surface, windows and guide sections. By using these built-in elements, a constant mixing of the product flow during heat transfer is achieved and thus uneven distribution and axial backmixing are prevented. At the same time, the flow path is extended and thus heat transfer is improved. The product flows in the outer chamber (6) of the tube bundle heat exchanger (1) which is provided with an inlet (2) and an outlet (3) for the product and an inlet (4) and an outlet (5) for the heat carrier medium in the tubes (7). The deflection panel (or deflection surface) (8) of the tube bundle heat exchanger is modified such that it opens the windows (12, 13) and at least one guide section (10 or 11) is attached to the inlet side and the outlet side of the deflection surface. These guide sections extend parallel to the tube axis and cross each other. The flow is separated by the guide section on the inlet side and guided in opposite directions to the windows, where it then leaves on the respective opposite sides of the outlet section and is deflected.

Description

Technical Field

[0001] The present invention relates to a bundle heat exchanger including, in an external chamber, a component formed by a deflection surface and a guiding section, which may or may not be designed as a built-in element. Background Art

[0002] Since bundle heat exchangers are usually made of metallic materials, we usually refer to a deflection panel rather than a deflection surface. However, in the present specification, the term "deflection surface" is used to clearly indicate that its applicability is not limited to heat exchangers made of metallic materials.

[0003] The bundle may consist of a number of tubes through which a heat exchange medium, such as a heating or cooling medium for heating or cooling a product circulating in the external chamber, is guided. However, alternatively, other heat exchange elements combined into a bundle, such as electric heating rods, electric heating coils, etc., may also be used. For simplicity of illustration, the terms "tube" or "tube bundle" will be used hereinafter, although it should be understood after what has been described that it also means other elongated heat exchange elements such as heating rods.

[0004] The usual design of the deflection panel or deflection surface serves as a flow guide by guiding the flow of the fluid in the outer chamber partly transversely and partly parallel to the tubes. These metal plates have holes corresponding to the tube spacing, which are perpendicular to the tubes, and segment-shaped windows for the axial passage of the fluid. Other known embodiments consist alternately of disks and rings. They are installed as standard components in turbulent (low-viscosity fluids) and laminar (viscous fluids) flows. For further functional and structural details, refer to Sections Gg5 and Ob7 of the VDI Heat Atlas (6th Edition). These deflection surfaces improve heat transfer due to more or less significant cross-flow reaching the tubes, but they do not cause any mixing of the fluid. This applies particularly in the case of laminar flow of viscous fluids. Since these materials have a low heat transfer coefficient due to their nature, they should be guided around the tubes (Section Ob4 of the VDI Heat Atlas). In the case of viscous media that have to be cooled or heated, the viscosity can change significantly with temperature. The partial flows with different temperature-time profiles (flow paths) ultimately have very different properties. This applies particularly to viscosity. In the absence of constant mixing, preferred paths and dead zones are formed, known as maldistribution. This can lead to complete failure of the heat exchanger and also to poor product properties. The problem is similar when the heat exchanger is used as a polymerization reactor or for other exothermic reactions with viscous liquid substances, see, for example, pages 214 - 220 of Chemical Engineering and Technology (Chem Eng. Technol.) 13 (1990). Here, differences in flow rate and viscosity also lead to maldistribution. Similar problems occur in shell-and-tube heat exchangers where a viscous solution partly evaporates and the viscosity increases sharply during this process.

[0005] Many static mixers (such as X mixers (SMX, SMXL)) or helical mixers (Kenics mixers) are preferably used with laminar flow in double-jacket tubes to improve heat transfer, mixing, and residence time distribution simultaneously, see pages 18 - 21 of Process Engineering 34 (2000), issues 1 - 2. There are narrow limits to the scaling up of these devices because the ratio of heat transfer surface to product volume decreases with increasing tube diameter, or if the tube diameter remains constant, the pressure loss will increase rapidly with increasing product quantity. As a solution, attempts are being made to also use static mixers in the tubes of shell-and-tube heat exchangers where the product flows through the tubes. Then, mixing still occurs within the individual tubes, but the partial flows in the tubes are completely isolated from each other, and different flow states and product properties can form in the individual tubes. The result can again be significant maldistribution with the described effects in the tubes. The higher pressure loss of the mixing elements makes the problem even worse. Another disadvantage of the reaction product is the additional volume in the shell of the shell-and-tube device. There is little or no heat transfer in this space.

[0006] DE 28 39 564 C2 proposes a device for heat transfer and static mixing. In this mixer - heat exchanger or reactor (referred to as the SMR reactor), the product also flows through flow channels with tube bundles and flows around the tubes in an outer chamber. The tubes are bent in a zigzag manner to form coiled tubes. The tubes are at an angle of 45° to the flow direction, cross each other and form a mixer structure. Individual coiled tubes are led outwards through the channel wall into a collector. Thus, simultaneous mixing and good heat transfer in the outer chamber are achieved, but with a large amount of work and many drawbacks. Compared with known mixers consisting of cross - sections, the mixing effect is less and occurs only in one direction within the bundle or mixing element. For practical reasons, the tube bundle should be as long as possible. Therefore, only a few bundles rotated by 90° can be used in the flow channel. Each mixing element or tube bundle of coils requires its own collector for the heat - carrier medium. Due to the long coiled tubes and many tube bends, the pressure loss on the heat - carrier side in the tubes is high. Coiled tubes of different lengths result in an uneven distribution of the flow on the heat - carrier side and, in turn, can lead to uneven distribution on the product side.

[0007] Due to the construction of the bundle, a favorable counter - current of the heat - carrier medium and the product in the tubes or evaporation or condensation are also not possible.

[0008] A further solution to the problem is sought in EP 1 067 352 B2. The mixing element with cross - sections according to the known SMX structure is provided with holes corresponding to the tube pitch of a tube - bundle heat exchanger, and the tubes are inserted through the sections. Connecting the mixing structure to the tube arrangement limits the freedom of tube pitch and size on the one hand and the freedom of the mixer structure on the other hand. If the sections are not firmly connected to the tubes, this structure is also mechanically rather weak. In terms of process technology, this heat exchanger may be superior to the design according to the previous paragraph, but its manufacture is extremely complex and demanding. Summary of the Invention

[0009] The object of the present invention is to form a tube - bundle heat exchanger, mixer - heat exchanger or mixing reactor of the type mentioned at the beginning that avoids the disadvantages of the prior art.

[0010] The tube - bundle heat exchanger according to the present invention is particularly suitable for viscous products and can be manufactured very inexpensively. In this tube - bundle heat exchanger, the product can be heated, cooled or evaporated, and an exothermic reaction can be carried out with simultaneous intense mixing. In the case of low axial back - mixing and low pressure loss, it has no moving parts. The formation of uneven distribution is prevented, and if necessary, the fixing means can be easily accessed from the outside for cleaning. The device is also very easy to scale. The arrangement and number of the extended (axially aligned) tubes (or other heat - exchange elements) through which the flow passes can be freely selected. Brief Description of the Drawings

[0011] Advantageous embodiments of the present invention are shown in the drawings and are explained in more detail below. In the drawings:

[0012] Figure 1 is a longitudinal section through a tube bundle heat exchanger according to the present invention,

[0013] Figure 2 is a perspective view of the tube bundle heat exchanger,

[0014] Figure 3 is according to Figure 1 a view of the inlet side of the built-in element,

[0015] Figure 4 is a view of the inlet side of the next built-in element in the flow direction,

[0016] Figure 5 is a view of the inlet side of the built-in element in an alternative embodiment, and

[0017] Figures 6 - 8 shows a further embodiment of the inlet side of the built-in element,

[0018] Figures 9 - 16 are various views and sections of an embodiment of the present invention, and

[0019] Figure 17 is according to Figures 9 - 16 a perspective view of an embodiment. Detailed Description

[0020] Generally referring to the drawings, the product flows in the shell space of a tube bundle heat exchanger known per se, which has an inlet 2 and an outlet 3 for the product in the outer chamber 6. An inlet 4 and an outlet 5 are provided for the heat carrier medium flowing in the tubes 7. According to the present invention, a deflector panel (or deflector surface) 8, which is usually present, perpendicular to the tubes or perpendicular to the axis of the heat exchanger and has holes 7' for the tubes, is modified such that it opens two or more windows 12, 13 for the axial passage of the product from the inlet side of the deflector surface to the outlet side. At least one guiding section 10 or 11 is attached to each of the inlet side and the outlet side, respectively. These guiding sections extend parallel to the tubes and subdivide the cross-section of the tube bundle into a number of parts of substantially the same size. If necessary, the deflector surface can also be arranged at an angle to the heat exchanger or tube axis, see reference numeral 9.

[0021] The guiding sections 10, 11 on the inlet side and the outlet side of the deflection surface are preferably at 90° to each other. The product flow is split in opposite directions by the guiding section 10 on the inlet side, reaches the windows 12, 13 transversely to the tube; the deflection surface passes through in the axial direction and leads to the opposite side of the guiding section 11 on the outlet side, and is preferably deflected by 90° in the direction of the guiding section. The flow direction of the partial flow transversely to the tube on the outlet side is again opposite on both sides of the guiding section 11. The deflection surfaces with windows and cross guiding sections each form built-in elements A or B. The guiding sections 11, 10' of the continuously arranged built-in elements (A, B) in the flow direction preferably cross each other at 90°. The closed partial surfaces of the continuously arranged built-in elements A, B and the windows 12, 12' and 13, 13' alternate.

[0022] In each built-in element, in the case of laminar flow, it is split into partial flows and mixed as follows: In each built-in element, in the case of simultaneous intense heat transfer, the number of layers is at least doubled (with two partial flows or one guiding section on the inlet side and the outlet side). In the entire device, the number of layers formed increases exponentially from the inlet to the outlet together with the number of built-in elements arranged one after another in the flow direction. This process can be demonstrated on the basis of tests with a fast-hardening, tough polyester resin. In the case of turbulent flow, the mixing is intensified by the turbulence. The axial distance between successive deflection surfaces preferably corresponds to the height of two guiding sections, with no distance between them. However, the installation can also be carried out with a spacing, or be shortened by guiding sections pushed into each other. Instead of two windows with guiding sections in the middle between the inlet side and the outlet side, the deflection surface can also have a plurality of windows 25, 26, 27 and a plurality of pairs of guiding sections (21, 22 and 23, 24). It is also possible that the number or the height of the guiding sections on the inlet side and the outlet side is different. This increases the intensity of mixing, but also increases the workload and the pressure loss.

[0023] The guiding sections according to the invention extend the flow path in the external chamber. This also increases the flow velocity and the heat transfer around the tube. Intense mixing simultaneously prevents axial backmixing. The more numerous the successive components / built-in elements in the heat exchanger and thus the more streamlined the device, the narrower the residence time distribution will be, similar to a cascade stirred tank reactor. In contrast to the fixing device according to the invention, all previously known deflection panels (or deflection surfaces) for heat exchangers do not cause any mixing in the case of laminar or viscous products. The heat transfer is only improved due to a better cross-flow to the tube. The product flow is only redirected, not split and mixed.

[0024] Figure 1The built-in elements A and B according to the invention, which consist of a deflection surface and an associated guide section, in a U-tube heat exchanger with an extendable tube bundle, are shown by way of example. The housing 1 of the device is shown as being axially cut open a little in front of or in front of the center of the guide section 11 on the outlet side of the built-in element, and the built-in element is shown in the view. The built-in element consists of a closed partial surface, windows, and associated guide sections on the inlet and outlet sides. The built-in element can be connected to the tubes loosely or firmly in whole or in part by brazing, welding, or gluing. The individual components of the built-in element are also connected at least in part in this way.

[0025] In a further embodiment, in accordance with the convention of a conventional deflection panel, the fixing devices are connected to each other and to the device by holding rods. It is also possible to flex a sub-element consisting of a guide section and a closed partial surface made of sheet metal. The arrangement shown with U-tubes is merely an example. Of course, the built-in element is also suitable for all other tube bundle heat exchangers, such as those with fixed straight tubes and tube sheets or those for multi-threaded devices. A non-circular (e.g., square or rectangular) cross-section of the device would also be possible. For heating of liquids, electric heating rods or heating coils can be used instead of tubes with a heat carrier medium.

[0026] Figure 2 A three-dimensional representation of a tube bundle 7 with a built-in element according to the invention, which includes windows 12, 13, a closed partial surface, and guide sections 10, 11, is shown. The closed partial surfaces and windows of successive built-in elements cover each other, and successive guide sections preferably cross each other at an angle of 90°.

[0027] Figure 3 A view of the inlet side of a built-in element A according to the invention, with a deflection surface 8 and two guide sections 10, 11, two windows 12, 13, and holes 7' in the closed partial surface for the tubes, is shown. The surface area of the windows generally roughly corresponds to that of the closed partial surface. However, the windows can also be made much smaller or of a different shape, such as slots or holes, in order to produce special flow effects or additional pressure losses or to prevent the formation of strands.

[0028] Figure 4 A view of the inlet side of the next built-in element B according to the invention, in the flow direction, with a deflection surface 8' and two guide sections 10', 11', two windows 12', 13', and holes 7' for the tubes. The closed partial surface and the windows are offset with respect to Figure 3 the previous built-in element shown in

[0029] In Figure 5 an alternative embodiment is shown. Figure 5View of the inlet side of a built-in element according to the invention, which comprises a deflection surface 8 with a hole 7' for a tube, and two guide sections 10, 11 and two windows 12, 13, wherein the windows have a surface area which is substantially smaller than that of the deflection surface and are of any shape.

[0030] Figure 6 View of the inlet side of another built-in element according to the invention, which has a deflection surface 8 and four guide sections 21, 22, 23, 24 and three windows 25, 26, 27 and a hole 7' for a tube.

[0031] Figure 7 View of the inlet side of a built-in element according to the invention, which has a deflection surface 8 and only one guide section 10 on the inlet side, two guide sections 23, 24 and three windows 25, 26, 27 and a hole 7' for a tube.

[0032] Figure 8 View of the inlet side of a built-in element according to the invention, which has a deflection surface 8' and only one guide section 10' on the inlet side, two guide sections 23', 24' and three windows 25', 26', 27' and a hole 7' for a tube, which follows the built-in element in front of it according to Figure 7 The windows are each offset from the windows of the element according to Figure 7 such that if the elements are arranged one after the other in the flow direction, a direct axial passage is not possible.

[0033] In Figures 9 to 17 is shown a detailed illustration of a variant of the invention based on Figure 7 and Figure 8 The figures are not all shown to the same scale. For reasons of illustration, the housing 1 has been omitted. Figure 9 Plan view of a tube bundle of a heat exchanger according to the invention with a deflection surface, windows and guide sections. The heat exchange medium (heat or coolant) flows through the tubes in the direction of arrow 28. Here, the guide sections are provided with reference numerals 10a to 10e. Other guide sections 10a', 10a” to 10e', 10e” are positioned at an angle of 90° thereto, wherein the guide sections are each connected at right angles to the deflection surfaces 8a', 8a”; 8b'; 8c', 8c”; 8d'; 8e', 8e”. The reference numerals 8a', 8a”; 8b'; 8c', 8c”; 8d'; 8e', 8e” denote deflection surfaces having openings or holes for the tubes to pass through. The deflection surfaces are also interrupted by the windows 12a'; 12b', 12b”; 12c'; 12d', 12d”; 12e'. The geometry of the deflection surfaces and the windows cut out therein alternate between the deflection surfaces, as will be explained in more detail below.

[0034] Figure 10Shows the same structure as Figure 9 , but this time shown in the direction of arrow X in Figure 9 . Figure 11 is a plan view of the marked sections XII-XII and XIII-XIII as seen from the direction of arrow XI in Figure 9 , and the said sections can be found in Figure 12 and Figure 13 respectively.

[0035] In Figure 9 , the sections XIV-XIV, XV-XV and XVI-XVI are also indicated. These sections are shown in Figure 14 , Figure 15 and Figure 16 respectively. The said sections show continuous deflection surfaces, each having a geometry complementary to the previous (or next) deflection surface in order to ensure the best mixing of the products to be mixed. Thus, Figure 14 the deflection surface shown in has a (covering) partial surface that deflects the product flow and only has one hole for the tube. There is an (open) window 12a' in the middle, which does not provide any resistance to the flow and is only crossed by two tubes. Figure 15 The deflection surface shown in is complementary to the deflection surface of Figure 14 , that is, it has a partial surface where the window is located in the deflection surface of Figure 14 and a window where the partial surface is located in the deflection surface of Figure 14 . In each case, the reverse applies to the lower half of the deflection surface not provided with reference numerals. Thus, the products flowing through the mixer / heat exchanger are forced to take different paths from deflection surface to deflection surface, which results in the best mixing of the fluid. According to Figure 16 , the third section corresponds again to the section of Figure 14 .

[0036] For further illustration, Figure 17 finally there is a perspective view of the shell-and-tube heat exchanger described with reference to Figures 9 to 16 , where arrow 28 indicates the flow direction of the product (see Figure 9 ). For clarity, this figure is not provided with reference numerals, but these can be obtained from Figures 9 to 16 .

[0037] The said components or built-in elements and their parts (such as deflection surfaces and guiding sections) can be made of steel and welded in a manner known per se. However, castings can also be used. Finally, it is also possible to be made of plastics, for example by injection molding or by additive manufacturing such as 3D printing.

Claims

1. A bundle heat exchanger for transporting or dissipating heat and simultaneously for mixing a product stream, comprising a bundle of at least two extended heat exchange elements, such as tubes (7), electric heating rods or heating coils, wherein, The product flow in the outer chamber (6) flows from the inlet opening (2) to the outlet opening (3), and it has at least two fixed components (built-in elements A, B) including at least one deflection surface (8, 8', 8a', 8a"; 8b'; 8c', 8c"; 8d'; 8e', 8e"), and is characterized in that: at least two windows (12, 13, 12', 13', 12a'; 12b', 12b"; 12c'; 12d', 12d"; 12e', 25, 26, 27, 25', 26', 27') in the deflection surface (8, 8', 8a', 8a"; 8b'; 8c', 8c"; 8d'; 8e', 8e"), the windows lead from the inlet side to the outlet side, and thus it is characterized in that: at least one guiding section (10, 11, 10', 10a - 10e, 10a' - 10e', 10a" - 10e", 23, 24) parallel to the extending heat exchange element is attached to the inlet side of the deflection surface (8, 8', 8a', 8a"; 8b'; 8c', 8c"; 8d'; 8e', 8e") and at least one guiding section (10, 11, 10', 10a - 10e, 10a' - 10e', 10a" - 10e", 23, 24) parallel to the extending heat exchange element is attached to the outlet side of the deflection surface (8, 8', 8a', 8a"; 8b'; 8c', 8c"; 8d'; 8e', 8e"), and is characterized in that: the partial surface of the deflection surface (8, 8', 8a', 8a"; 8b'; 8c', 8c"; 8d'; 8e', 8e") not provided with windows (12, 13, 12', 13', 12a'; 12b', 12b"; 12c'; 12d', 12d"; 12e', 25, 26, 27, 25', 26', 27') has one or more holes or openings (7') for the heat exchange element to pass through according to its spacing in the bundle of heat exchange elements, wherein the guiding section on the inlet side and the guiding section on the outlet side cross each other at an angle of 90°.

2. The bundled heat exchanger according to claim 1, characterized in that: The tube bundle heat exchanger has a circular cross-section.

3. The bundled heat exchanger according to claim 1 or claim 2, characterized in that: The axial distance between the continuous deflection surfaces (8, 8', 8a', 8a"; 8b'; 8c', 8c"; 8d'; 8e', 8e") corresponds to the height (h) of the two guiding sections, and there is no distance between them.

4. The bundled heat exchanger according to claim 1 or claim 2, characterized in that: The windows (12, 13, 12', 13', 12a'; 12b', 12b"; 12c'; 12d', 12d"; 12e', 25, 26, 27, 25', 26', 27') are arranged on the opposite sides of the guiding sections (10, 11, 10', 10a - 10e, 10a' - 10e', 10a" - 10e", 23, 24).

5. The bundle type heat exchanger according to claim 1 or claim 2, characterized in that: A plurality of components (built-in elements A, B) with deflection surfaces (8) that remain transverse to the heat exchange elements are arranged one after another in the flow direction, and are characterized in that: on the one hand, the windows (12, 13) of the components (built-in elements A, B) alternate with the surface portions of the deflection surface (8') of the next component (built-in elements A, B) that are not provided with windows (12, 13), and on the other hand, the surface portions of the previous component (built-in elements A, B) that are not provided with windows (12, 13) alternate with the windows (12', 13') of the subsequent component (built-in elements A, B).

6. The bundled heat exchanger according to claim 5, characterized in that: The guiding sections (11, 10') of consecutive components (built-in elements A, B) cross each other at an angle of 90°.

7. The bundled heat exchanger according to claim 1 or claim 2, characterized in that: The beam cross-section is divided into partial surfaces of equal size by the guiding sections (10, 11, 10', 10a - 10e, 10a' - 10e', 10a'' - 10e'', 23, 24) of the components (built-in elements (A, B)).

8. The bundled heat exchanger according to claim 1 or claim 2, characterized in that: The partial surfaces of the components (built-in elements A, B) provided with windows (12, 13, 12', 13', 12a'; 12b', 12b''; 12c'; 12d', 12d''; 12e', 25, 26, 27, 25', 26', 27') and the partial surfaces not provided with windows (12, 13, 12', 13', 12a'; 12b', 12b''; 12c'; 12d', 12d''; 12e', 25, 26, 27, 25', 26', 27') are of the same size.

9. The bundled heat exchanger according to claim 1 or claim 2, characterized in that: The partial surfaces of at least one component (built-in elements A, B) provided with windows (12, 13, 12', 13', 12a'; 12b', 12b''; 12c'; 12d', 12d''; 12e', 25, 26, 27, 25', 26', 27') to achieve a specific flow effect are significantly smaller than the partial surfaces of the deflection surface not provided with windows (12, 13, 12', 13', 12a'; 12b', 12b''; 12c'; 12d', 12d''; 12e', 25, 26, 27, 25', 26', 27').

10. The bundled heat exchanger according to claim 1 or claim 2, characterized in that: The number of guiding sections (10, 11, 10', 10a - 10e, 10a' - 10e', 10a'' - 10e'', 23, 24) is different on the inlet side and the outlet side.

11. The bundled heat exchanger according to claim 1 or claim 2, characterized in that: The height (h) of the guiding sections (10, 11, 10', 10a - 10e, 10a' - 10e', 10a'' - 10e'', 23, 24) is different on the inlet side and the outlet side.

12. A method of heat transfer with a viscous product using a bundle heat exchanger according to any one of the preceding claims.

13. A method of using a bundle heat exchanger according to any one of claims 1 to 11 as a reactor in an exothermic or endothermic reaction.

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