EP2299226B1 - Tubular heat exchanger with bellows compensator - Google Patents

Description

The invention relates to a tubular heat exchanger specified in the preamble of claim 1. Art.

At one off DE3602608 A1 known, generic tubular heat exchanger, the inner and outer tube congruent bellows, which contain substantially zig-zag-shaped, rounded at the inflection points convolutions, which are similar in cross-section. In the folds, the ratio between the axial width and the radial depth is significantly more than 2. The straight flanks and the relatively sharp curves of the inflection points of the folds create dead spaces in which impurities can settle and which are very difficult to clean to produce a hygienic condition in the bellows. In addition, the compensation effect occurs predominantly in the inflection points, which are thus subjected to high local stresses.

At one off WO 204092638 A1 known compensating bellows for pipelines is the folds having inner tube protected by a smooth continuous outer tube. There is no product flow between the inner and outer tubes. In the embodiment of the Fig. 3 At the top, narrower V-shaped folds are provided at intervals between substantially trapezoidal, relatively wide folds. In the relatively further convolutions, the ratio B: T is clearly greater than 2, while the ratio B: T is 1 in the relatively narrow convolutions. The relatively small radii of curvature of the trapezoidal, relatively further folds create dead spaces in which impurities threaten to settle and which are difficult to clean. The compensation effect takes place predominantly in the radii of curvature between the straight ridges of the trapezoidal folds and the straight edges of the relatively narrow folds, so that local high tensions occur there. The straight edges of the relatively narrower folds and the straight ridges and bottoms of the trapezoidal, relatively further folds take part in the compensation hardly.

At one off US3817319 A known heat exchanger tube are in the embodiment of Fig. 2 a, 2 b helical like folds with V-shaped cross-section and relatively narrow curves provided in the inflection points. The ratio between B: T is about 1.5.

At one off US 4186779 A known heat exchanger tube, which is formed by roll forming with a bellows, the ratio of B: T is almost exactly 1, wherein the Contour of the folds is defined by harmoniously merged arc sections.

Tubular heat exchangers, for example for product versus product flow guidance are out DE 600 19 635 T2 and DE 102 56 232 B4 known. The thermal expansion compensation device is in this case a sliding connection with seals or a floating or floating bearing that allows thermally induced relative movements, however, causes dead spaces in which the product can settle so that it is no longer removable despite intensive cleaning, or the hygienically flawless Cleaning requires disassembly. For reasons of hygiene, such compensation devices are not recommended by the competent authorities, but have hitherto been customary as a compromise solution for the product versus product flow guidance.

In tubular heat exchangers in the food industry, where a flow guide product takes place against heat transfer medium such as water, it is known, however, to install as a thermal expansion compensation means at least one bellows so that is contacted exclusively by the heat transfer medium, however, by no means the product. The bellows is not cleaned after certain periods of use of the tube heat exchanger or a product change, since it is in contact only with the heat transfer medium anyway. The bellows is deliberately designed with a ratio of B: T of much smaller than 1, possibly with straight flanks and very small radii of curvature between the flanks, because this makes the compensating effect per fold strong and therefore as few folds as possible are needed. This bellows could be because of the favorable for the compensation ratio of B: T much less than 1 no longer clean to a hygienic condition, since upon contact with a product, for. due to vortices and dead zones inevitably firmly adhering product deposits would occur.

The invention has for its object to make a tubular heat exchanger of the type mentioned with good compensation effect of the bellows for a product against product flow guide hygienically cleanable.

The stated object is achieved with the features of claim 1.

With the deliberate departure from the customary for an optimal thermal expansion compensation ratio of B: T of the folding to a less favorable for the compensation ratio of B: T of about 1 or greater at least on the contact surface of the fold of the product, the possibility arises to clean the surface contactable by the product to a hygienic condition, because there are relatively moderate changes of direction in the rounded folds, relatively weakly curved surfaces and no critical dead spaces. The product thus tends less to adhere, but is always flushed out of the fold quickly. Cleaning media can efficiently remove product residues and are even easily rinsed and / or removed without residue. In order to achieve the total required compensation effect, only a corresponding number of folds need to be provided, which however is perfectly acceptable with regard to the achievable, hygienic conditions for the product against product flow guidance and the hermetic tightness in the tubular heat exchanger. By accepting the deterioration of the compensating effect of each, for example, with its inside with the product in contact, provided for the technical purpose of the compensation of thermal expansion relatively wide folds, but the bellows receives only the hygienic suitability of the product against product flow guidance in the tube heat exchanger , also because very favorable flow conditions are achieved by a harmonious surface course, which drastically improve especially the cleaning efficiency. It is thus achieved a tubular heat exchanger with hygienic bellows. In this case, a plurality of axially successive, substantially similar folds are provided inwardly or outwardly, which are formed on the product contactable surface with the ratio of B: T of about 1 or greater, and are provided in the intermediate intervals folds, the are formed with a ratio of B1: T <1. The convexly curved surfaces of the folds with the ratio B1: T <1 can be arranged on the product-contactable surface of the bellows, because these convex surface sections too are easy to clean. This is a hybrid design of the bellows, on the one hand to be able to clean well the concave surface portions of the relatively wide folds with the ratio B: T of about 1 or greater, but to achieve a lower compensation effect per unit length, and on the other hand also at the convex surface areas To be able to clean folds with the ratio of B1: T <1 sufficiently well, but there to obtain a stronger compensation effect per unit length. This hybrid form of bellows is recommended for the jacket tube when it is contacted by the product on the inside surface. In this case, each fold is formed in an axial section of the inner and / or jacket tube equipped with the bellows from continuously arcuate circular arc sections having a radius of curvature corresponding to approximately half the depth and / or width of the respective fold.

In an expedient embodiment, in the relatively wide convolutions, the ratio of B: T may be between about 1 and up to 2. The larger the ratio, the better the folding behaves when cleaning after prescribed operating periods or to a product change.

In another embodiment, the inner diameter of the bellows has a size that is between approximately the inner diameter of the bellows-containing inner or outer tube and this inner diameter minus the depth of the convolutions. Depending on the application of the bellows in the jacket tube or in an inner tube, unwanted bottlenecks in the respective flow channels can be avoided or minimized within this inner diameter of the bellows.

In one embodiment, the bellows with the inner or jacket tube welded, substantially circular cylindrical Rohrendstutzen, which are inserted into or over inner or casing tube section ends. The integration of the bellows in the respective tube is easy to master manufacturing technology. The welds are tight and tolerate easily high pressure differences. The bellows can be arranged at the respectively optimal position of the tube.

In an alternative embodiment, the bellows is integrally formed in the circular cylindrical wall of the respective tube, for example by a rolling or rolling treatment or by hydraulic forming. This eliminates the need for welded joints.

In an expedient embodiment, a jacket tube with a plurality of inner tubes forms a tube heat exchanger module. The bellows, at least one bellows, can be arranged approximately in the longitudinal center of the heat exchanger module in order to optimally develop its compensation effect. Preferably, the bellows is in the jacket tube, such that the surface of the bellows which can be contacted by the product faces the inner tubes accommodated in the jacket tube, which can be smooth.

With regard to efficient cleaning, it is important if the fold has such a harmonious surface course, at least on the surface that can be contacted by the product, that largely turbulent flow conditions are favored there, which completely cover all depressions of the bellows. Largely turbulent flow conditions offer the advantage of not creating zones in which not only settle the product threatens, but in which a cleaning medium could not develop an efficient cleaning effect.

Fig. 1

einen schematischen Längsschnitt eines Moduls eines beispielhaften Röhrenwärmetauschers,

Fig. 2

in vergrößertem Maßstab ein Detail aus Fig. 1 mit einem Faltenbalg in einem Mantelrohr des Röhrenwärmetauscher-Moduls,

Fig. 3

einen Achsschnitt einer anderen nicht unter die Erfindung fallenden Ausführungsform, beispielsweise eines Mantelrohres oder einen Innenrohres eines Moduls,

Fig. 4

einen Achsschnitt einer weiteren nicht unter die Erfindung Fallenden Ausführungsform eines Mantel- oder Innenrohres eines Moduls, und

Fig. 5

einen Teilschnitt einer konkreteren Ausführungsform eines Moduls.

Embodiments of the subject invention will be explained with reference to the drawings. Show it:

Fig. 1

a schematic longitudinal section of a module of an exemplary tubular heat exchanger,

Fig. 2

on a larger scale a detail Fig. 1 with a bellows in a jacket tube of the tube heat exchanger module,

Fig. 3

an axial section of another not falling under the invention embodiment, for example, a jacket tube or an inner tube of a module,

Fig. 4

an axial section of another not falling under the invention embodiment of a jacket or inner tube of a module, and

Fig. 5

a partial section of a more concrete embodiment of a module.

The Fig. 1 and 5 illustrate in each case a single module M of a dashed line indicated tubular heat exchanger W, as used for example in the filling industry for liquid food products (eg water, juices, milk) to a product against product flow guidance in the heat treatment (heating or cooling) of a food product. In the tubular heat exchanger W several modules can be installed to achieve the longest possible flow paths for the product. The module M may be, for example 3.0 m, 6.0 m long, or even longer.

The module M points in Fig. 1 a jacket tube 1, for example made of stainless steel, on, the end-side mounting flanges 2 for mounting in the tube heat exchanger W has. In the jacket tube 1, at least one inner tube 3 is provided, which extends substantially parallel to the jacket tube 1 between mounting flanges 4. In the embodiment in FIG Fig. 1 are provided a plurality of inner tubes 3, which are combined to form a tube bundle, so that between the casing tube 1 and the inner tubes 3 and also in the inner tubes 3 at least the flow channels 5, 6, 7 and 8 are defined, wherein the channels 6, 7 and 8 belong to a primary flow and the channel 5 to a secondary flow channel. In these flow channels, the food product circulates, wherein optionally at least one flow path is also used for a heat transfer medium (in Fig. 1 eg the flow path 5). In order to be able to compensate for unavoidable thermal expansions between the tubes 1, 3 due to different temperatures in the flow paths, in the embodiment in FIG Fig. 1 integrated in the jacket tube 1, a compensation device K, which is designed as a bellows C with multiple folds F. It would be quite possible to provide several bellows C over the length of the module M (eg 6.0 m or more). The in Fig. 1 shown bellows C has on the inside a contactable by the product in the flow path 5 surface 12 and compensated by predominantly axial working the different axial thermal expansion of the casing tube 1 in relation to the axial thermal expansion of the inner tubes 3. In Fig. 5 are on the casing pipe 1 for the connection, for example, the inner tubes 3 open end flanges 2 and in the jacket tube 1 side ports 2 'are provided.

In addition, the inner tubes could be 3 equipped with bellows C, or only the inner tubes 3, in which case a bellows C in an inner tube 3 optionally inside and / or outside presents a contactable surface 12 of the product.

Fig. 2 shows the bellows C of Fig. 1 on a larger scale. The bellows C is welded with end-side, eg circular cylindrical Rohrendstutzen 10 with the jacket tube 1, and Although inserted here in jacket pipe section ends 1a, 1b inside and welded at 11. Alternatively, the pipe end pieces 10 could also be plugged and welded on the outside of the jacket pipe section ends 1a, 1b. The bellows C is prefabricated and subsequently installed in the jacket tube 1.

The bellows C in Fig. 2 is characterized by the fact that it has a plurality of axially spaced successively arranged around the tube axis X, relatively wide folds F having a radial depth T and an axial width B and are similar to each other. The ratio of B: T is about 1 or even greater, preferably up to about 2. The product-contactable surface 12 is primarily concavely rounded and relatively harmonic with, for example, a radius of curvature R1 that is about half the depth T or Width B may be.

Opposite folds F1 'are provided in the spaces between the axially spaced folds F, each having on the product-contactable surface 12 a convex surface portion with a radius of curvature R2' smaller than half the depth T or ready B, and approximately can be half the width B1 of the fold F1 '.

The inner diameter of the bellows C is indicated by d and corresponds approximately to the inner diameter D of the jacket tube 1. The outer diameter D1 of the bellows C corresponds approximately to the inner diameter d plus twice the depth T and plus the material thickness of the bellows C. The bellows C is, preferably as well as the jacket tube 1, made of stainless steel. The inner tubes 3 are in Fig. 2 Not shown. The outer surface 9 of the bellows C does not come into contact with the product in the module M.

In the embodiment in FIG Fig. 3 the bellows C is integrated either in the jacket tube 1 or in the respective inner tube 3. If the bellows C is located in the inner tube 3, then the inner and outer surfaces 12 can be contacted by the product here. In the bellows C several axially directly consecutive, alternately inwardly and outwardly shaped folds F, F1 are formed, which may be similar, and consecutively convex and concave curvatures, suitably with radii of curvature R1, R2 corresponding to about half the depth T. It is expedient around steplessly guided into each other circular sections, preferably semicircles. The inner diameter d1 of the bellows C corresponds approximately to the inner diameter d of the jacket or inner tube 1, 3, or its outer diameter d, while the outer diameter D1 of the bellows corresponds approximately to the outer diameter D plus twice the depth T and the material thickness. In the illustrated embodiment for an inner or jacket tube 1, 3 with an outer diameter D of about 70.0 mm, the width B of each fold is just under 10.0 mm, the depth T of each fold is also about 10.0 mm, and are over the length of the bellows C six folds F and five folds F1 provided.

In the embodiment in Fig. 4 the inner diameter d1 of the bellows C is smaller than the inner diameter d of the jacket or inner tube 1, 3, preferably to a maximum about the depth T smaller, and the outer diameter D1 of the bellows C is slightly larger than the outer diameter D or almost equal to the outer diameter D. Also in the bellows C in Fig. 4 are axially directly successive multiple folds F, F1 provided alternately inwards and outwards, which may be similar.

In the embodiment of Fig. 4 When the outer diameter D is about 114.0 mm, the length of the bellows C is about 146.0 mm, the depth T is about 12.0 mm, and the width B is about 11.0 mm.

In each embodiment, the ratio B: T of the convolution F, F1 is selected to be about 1.0 or greater, preferably to a maximum of about 2.0.

The ratio may be slightly smaller than 1, but preferably always more than 0.9.

Preferred embodiments have a sheath diameter of up to 250 mm. However, it can also occur shapes with larger diameters.

Claims (6)

1. Tubular heat exchanger (W) comprising a casing tube (1) and at least one inner tube (3) for treating liquid food products, particularly low-viscosity products, such as juices or milk, also with a product counter to product flow guidance, comprising at least one thermal-expansion compensating device (K) for the casing and/or the inner tube (1, 3), with the compensating device (K) having disposed therein at least one surface (12) which can be contacted by the product to be treated wherein the surface (12) which is contacted by the product is provided on at least one bellows (C) integrated into the casing and/or inner tube (1, 3), the surface (12) which can be contacted by the product being provided with a plurality of wide foldings (F1, F) which extend around the tube axis (X) and are of rounded cross-section, characterized in that a plurality of relatively wide foldings (F) which are axially successive with interspaces and substantially equal are provided inwards or outwards and are formed on the surface (12) which can be contacted by the product with the ratio B : T between an axial width (B) and a radial depth (T) of about 1 or more, that narrower foldings (F1') are provided in the interspaces, the narrower foldings (F1') being configured with a ratio of B1 : T of less than 1, and that each folding (F, F1) is formed in an axial section of the inner tube or casing tube (3, 1) of circle arc sections continuously passed into one another, the circular-arc sections having a radius of curvature (R1, R2, R2') corresponding to about half the depth (T) and/or the width (B).
2. Tubular heat exchanger according to claim 1, characterized in that the ratio of B : T of the relatively wide foldings (T), at least on the surface (12) which can be contacted by the product, ranges from about 1 to about 2.
3. Tubular heat exchanger according to at least one of the preceding claims, characterized in that the inner diameter (d1) of the bellows (C) has a size that is between approximately the inner diameter (d) of the inner tube or casing tube (1, 3) including the bellows and the inner diameter (d) minus the depth (T).
4. Tubular heat exchanger according to at least one of the preceding claims, characterized in that the bellows (C) comprises substantially circular cylindrical tube end sockets (10) which are welded to the inner tube or casing tube (3, 1) and which are inserted in or over inner-tube or casing-tube section ends (1a, 1b).
5. Tubular heat exchanger according to at least one of claims 1 to 3, characterized in that the bellows (C) is formed by a roller treatment or by hydraulic formation integrally in the per se circular cylindrical wall of the inner tube and/or casing tube (3, 1).
6. Tubular heat exchanger according to at least one of the preceding claims, characterized in that the casing tube (1) and a plurality of inner tubes (3) in the casing tube (1) form a heat-exchanger module (M), and that the bellows (C) is arranged approximately in the longitudinal mid of the heat-exchanger module (M), preferably in the casing tube (1) and with the surface (12) contacted by the product on relatively wide foldings (F, F1) with the ratio of B : T of about 1 or more facing the inner tubes (3).

Images