Coupling device, tubular heat exchanger and method for heat treating food products

Abstract

A coupling device (1) comprising: a tube sheet (112) attached to a tube bundle (110); a first groove (218) formed on a surface (220) of the tube sheet (112); a flange (208) provided to accommodate a terminal section (214) of the tube sheet (112) and provided with holes (226) for receiving fastening means (306a, 306b); an anchor ring (202) provided to be placed around the tube sheet (112) and provided with holes (210) for receiving fastening means (306a, 306b) to connect the anchor ring (202) to the flange (208); a retaining element (206) comprising an inner section (311) and an outer section (312), wherein the inner section (311) is provided to be placed in the first groove (218) of the tube sheet (112), wherein the retaining element (206) is divided into a first part (222) and a second part (224); and a second groove (232) formed by the combination of the flange (208) and the anchor ring (202) and provided to accommodate the outer section (312) of the retaining element (206).

Description

TECHNICAL FIELD

[0001] The present invention relates to a tubular heat exchanger for food processing. More specifically, it relates to a coupling device, a tubular heat exchanger and a method of heat treating food. BACKGROUND

[0002] Nowadays, it is common practice to use tubular heat exchangers in food processing applications. Tubular heat exchangers offer reliable operation and cost effectiveness. A tubular heat exchanger generally comprises a plurality of tube bundles in which food is conveyed. Each tube bundle comprises a number of parallel tubes. In a housing provided outside the tube bundle, a heat transfer medium can be provided so that the food in the tube bundle can be heated, thereby eliminating bacteria, spores and other micro-organisms that can cause health problems. By choosing the diameter of the tubes in accordance with the nature of the food, and by providing flow guiding grooves on the tubes, the food can be effectively heat treated. For certain products, it is also possible to make use of so-called regeneration, in which heated food is used to heat unheated food.

[0003] A further advantage of at least some of the tubular heat exchangers provided nowadays is versatility. Since a modular approach can be used, it is easy to replace, for example, tube bundles in case different products have to be processed. Therefore, it is generally a good choice to invest in a tubular heat exchanger, since it will be useful even if different types of products have to be processed.

[0004] Despite the many advantages of tubular heat exchangers, high viscosity products such as yoghurt can prove difficult to heat treat in a tubular heat exchanger. This results in the fact that often scraped surface heat exchangers or other equipment configured for high viscosity products are used. This has the disadvantage that often the operating costs increase and that such equipment is limited in versatility. SUMMARY

[0005] It is an object of the present invention to at least partially overcome one or more of the above identified limitations of the prior art. In particular, it is an object to provide a coupling device which enables a tubular heat exchanger to operate at high pressures, for example above 200 bar, and which enables high viscosity products such as products having a viscosity of 100 cP at 40°C to be heat treated in a tubular heat exchanger.

[0006] The present invention is achieved by designing a coupling device for a new type of tube which enables the forces resulting from high pressures to be reliably dealt with. The design not only provides a more versatile device in terms of the products which can be processed, but also a more versatile device in terms of the safety of the operator, in which it is possible to safely use equipment which operates at pressures above 200.

[0007] According to a first aspect, there is provided a coupling device comprising: a tube sheet arranged to be attached to a tube bundle; a first recess formed in a surface of the tube sheet; a flange arranged to receive an end section of the tube sheet and provided with holes for receiving fastening means; an anchor ring arranged to be placed around the tube sheet and provided with holes for receiving fastening means to be connected to the flange; a retaining element comprising an inner section and an outer section, wherein the inner section is arranged to be placed in the first recess of the tube sheet, wherein the retaining element comprises a first part and a second part; and a second recess formed by the flange and the anchor ring in combination and arranged to receive the outer section of the retaining element.

[0008] One advantage of the coupling device is that at least a portion of food products that need to be fed through the tubes at high pressure can be heat treated in the tubular heat exchanger by the coupling device. One reason for this is that the coupling device can withstand high pressure, e.g. above 200 bar, within the tube bundle.

[0009] The first part and the second part can each have a semi-annular shape.

[0010] At least one of the flange and the anchor ring is provided with a radial retaining element engagement surface to prevent radial movement of the retaining element when the anchor ring is attached to the flange.

[0011] The flange can be provided with a radial tube sheet engagement surface and an axial tube sheet engagement surface arranged towards the tube sheet.

[0012] The flange can be provided with a sealing groove arranged to receive a seal, wherein the axial tube sheet engagement surface can be arranged to prevent movement of the tube sheet in the axial direction A, thereby reducing the force F exerted on the seal by the tube sheet.

[0013] An outer section depth (OSD) of the outer section can be greater than an inner section depth (ISD) of the inner section of the retaining element.

[0014] The holes on the fastening means and the anchor ring can be threaded and arranged to interact to attach the anchor ring to the flange.

[0015] A benefit of this is that the fastening means can be easily installed without the need for an operator to reach behind the anchor ring.

[0016] According to a second aspect, there is provided a tubular heat exchanger comprising a coupling device according to the first aspect, a tube bundle arranged to convey food products and connected to the tube sheet, a shell arranged to enclose the tube bundle and a heat transfer medium, and a conduit connected to the flange.

[0017] In line with the advantages presented in relation to the first aspect, by using a coupling device according to the first aspect, the pressure P within the tube bundle can be increased. This makes it possible to heat treat high viscous products that currently cannot be heat treated in a tubular heat exchanger using this cost efficient heat exchanger type.

[0018] According to a third aspect, there is provided a method of heat treating a food product using a tubular heat exchanger according to the second aspect. The food product has a viscosity greater than 100 cP at a temperature of 40 °C, and the method comprises: feeding the food product from the pipe into the tube bundle by means of the coupling device; conveying the food product through the tube bundle; heating and feeding the heat transfer medium into the shell, thereby heating the food product to reduce microorganisms in the food product.

[0019] The pressure P in the tube bundle can be higher than 200 bar, and the pressure P' in the shell can be lower than 30 bar.

[0020] Other objects, features, aspects and advantages of the present application will become apparent to those skilled in the art from the following detailed description, together with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0021] Embodiments of the present application will now be described, by way of example, with reference to the accompanying drawings, in which

[0022] Figure 1 is a perspective view of a tubular heat exchanger.

[0023] Figure 2a is an exploded view of a coupling device.

[0024] Figure 2b is a perspective view of a coupling device.

[0025] Figure 3 is a cross-sectional view of a coupling device connected to a tube bundle and a pipe.

[0026] Figure 4 is a detailed cross-sectional view of a coupling device according to a first embodiment.

[0027] Figure 5 is a detailed cross-sectional view of a coupling device according to a second embodiment.

[0028] Figure 6 is a detailed cross-sectional view of a coupling device according to a third embodiment.

[0029] Figure 7 is a flow chart of a method for heat treating a food product. DETAILED DESCRIPTION

[0030] Reference will now be made to Figure 1Fig. 1 shows a tubular heat exchanger 100 comprising a coupling device 1. The tubular heat exchanger 100 can be a tubular heat exchanger of the type Tetra Spiraflo® marketed by Tetra Pak. TM

[0031] The tubular heat exchanger 100 has a number of tube bundles 110 which are connected to respective tube sheets 112, e.g. by welding. Each tube bundle 110 has a shell 302 surrounding the tube bundle 110. The tube bundles 110 are interconnected by connecting pipes 304. Thus, food product FP can flow from one tube bundle to another. Each tube bundle 110 comprises a number of straight pipes arranged in parallel. The connecting pipes 304 are connected to the tube bundles by the coupling device 1. The shell 302 surrounds the tube bundle 110 so that a heat transfer medium (HTM) such as hot water can flow within the shell 302 and around the tube bundle 110.

[0032] The tubular heat exchanger 100 can be operated in conditions where the coupling device 1 shows particular advantages, in particular when considering hygiene and pressure handling aspects and when considering the total cost of the tubular heat exchanger 100.

[0033] Figure 2a The coupling device 1 is further described in detail. In addition to the tube sheet 112, the coupling device 1 comprises an anchor ring 202, a retaining element 206 and a flange 208. The tube sheet 112 can be arranged to be placed within the flange 208, and the anchor ring 202 is arranged to be placed on the tube sheet 112 and to engage the flange 208. To this end, the anchor ring 202 can be provided with holes 210 for fastening means.

[0034] The tube sheet 112 is provided with holes 212 through which food product can be fed into the tube bundle 110. Typically, the tubes of the tube bundle are inserted into the holes 212 and then welded to the tube sheet 112. Furthermore, the tube sheet 112 has an end section 214 which is arranged to be insertable into the flange 208 and a top section 216 which is surrounded by the shell.

[0035] The end section 214 forms a recess 218 in a surface 220 of the tube sheet 112. The surface is typically a peripheral surface of the tube sheet 112, and the recess can form an annular groove in the tube sheet 112. The retaining element 206 can be arranged to be placed in the recess 218, and the retaining element can be divided into a first part 222 and a second part 224.

[0036] ​As shown, the two parts 222, 224 can have a semi-annular shape to fit the respective half-groove of the groove 218. Each of the two parts 222, 224 can have an angular extension of up to 180°. The two parts 222, 224 can have the same size and shape in the radial direction R. The two parts 222, 224 can have the same size and shape in the axial direction A. The two parts 222, 224 can be identical in size and shape.

[0037] The flange 208 can have holes 226 arranged to receive fastening means fed through the holes 210 of the anchor ring 202, such that in the mounted state, the anchor ring 202 can be engaged with the flange 208 as shown. Figure 2b The tube sheet 112 can have a first O-ring groove 228 and a second O-ring groove 230. This has the advantage that a so-called floating design can be realized for the shell 302, as will be further described below.

[0038] The flange 208 can be provided with a groove 232 arranged to accommodate the retaining element 206. Thus, by arranging a portion of the retaining element 206 in the first groove 218 of the tube sheet 112 and a portion of the retaining element 206 in the groove 232, the tube sheet 112 can be fixed in place by the retaining element 206 when the anchor ring 208 is connected to the flange 206.

[0039] Figure 3 A cross-sectional view of the coupling device 1 is shown in the assembled state.

[0040] The shell 302 surrounds the tube bundle 110 so that a heat transfer medium (HTM), such as hot water, can be transported between the tube bundle 110 and the shell 302. Furthermore, a connection tube 304 is connected to the flange 208, and fastening means 306a, 306b, such as bolts, can be used to connect the flange 208 to the anchor ring 202. For this purpose, the holes 210 of the anchor ring 202 can be threaded. This has the advantage that the fastening means 306a, 306b can be installed without having to reach behind the anchor ring 202.

[0041] In order to provide the floating design described, i.e. to allow the tube bundle 110 to move axially due to thermal expansion and contraction, a first O-ring 308a can be provided within the first O-ring groove 228, and a second O-ring 308b can be provided within the second O-ring groove 230. By providing these two O-rings, the risk of leakage of the heat transfer medium HTM can be reduced.

[0042] As mentioned above and Figure 3As shown, the retaining element 206 can be clamped between the tube sheet 112, the anchor ring 202 and the flange 208, i.e. it can be located in the recess 232 of the flange 208. In the flange 208, a sealing groove 309 can be provided for accommodating a sealing element 310. By means of the sealing element 310, a leak-tight fit between the tube sheet 112 and the flange 208 can be achieved.

[0043] As described above and as shown, a portion of the retaining element 206 can be accommodated in the first recess 218 of the tube sheet 112 and a portion of the retaining element 206 can be accommodated in the second recess 232 formed by the anchor ring 202 and the flange 208 in combination. More specifically, an inner section 311 of the retaining element 206 can be accommodated in the first recess 218 and an outer section 312 can be accommodated in the second recess 232. The second recess 232 can have a radial retaining element engagement surface 313 which faces radially against the retaining element 206 and extends in axial direction. In this way, the retaining element radial engagement surface 313 can cooperate with a peripheral surface 315 of the retaining element 206. As described above, the retaining element 206 can be divided into two parts, a first part 222 and a second part 224. When the pressure P in the tube bundle 110 increases, the two parts cannot move apart because the flange 208 blocks them in radial direction R.

[0044] Furthermore, the flange 208 can have an axial retaining element engagement surface 314 which faces axially against the retaining element 206 and extends in radial direction. Furthermore, the flange 208 can be further provided with a radial tube sheet engagement surface 316 which faces radially against the tube sheet 112 and extends in axial direction, and an axial tube sheet engagement surface 318 which faces axially against the tube sheet 112 and extends in radial direction. The axial tube sheet engagement surface 318 has the advantage that it can be provided to prevent a movement of the tube sheet 112 in axial direction A, thereby reducing the force F which the tube sheet 112 exerts on the sealing device 310.

[0045] The anchor ring 202 can have an axial retaining element engagement surface 319 which is arranged opposite to the axial retaining element engagement surface 314. The axial retaining element engagement surface 314 and the opposite axial retaining element engagement surface 319 prevent a movement of the retaining element 206 in axial direction A.

[0046] As shown, the second recess 232 comprises the radial retaining element engagement surface 313 and the axial retaining element engagement surface 314, while the opposite axial retaining element engagement surface 319 is part of the anchor ring 202. However, this is only one of several possibilities to realize the second recess portion 320, i.e. the portion of the second recess 232 provided in the coupling device 1, other possibilities being for example Figure 5 and Figure 6 as shown and will be described in the following.

[0047] Figure 4 It is explained how forces are formed due to the pressure P of the food FP inside the tube bundle 110. As shown, a tube sheet force F T may be exerted on the inner section 311 of the holding element 206. The tube sheet force F T may be transmitted through the tube sheet 112 and the inner side axial holding element engagement surface 400 of the first groove 218. The radial force F Ra may also be formed by the pressure P and transmitted through the tube sheet 112. As shown, the radial force F Ra may cause the holding element 206 to be pushed against the radial holding element engagement surface 313. Furthermore, due to the tube sheet force F T , the holding element 206 can be pushed towards the anchor ring 202, more specifically towards the opposite axial holding element face 319 of the anchor ring 202, thereby forming an anchor ring force F Ri Other forces can be exerted on the holding element 206 even though not explained.

[0048] As Figure 3 and Figure 4 shown, the radial holding element engagement surface 313 can be formed by the flange 208. As Figure 5 shown, another option is that the surface is partly formed by the flange 208 and partly by the anchor ring 202. As Figure 6 shown, yet another option is that the radial holding element engagement surface 313 is formed by the anchor ring 202 only. This implies that the groove that accommodates the outer section 312 of the holding element 206 can be formed in the flange 208 Figure 3 and Figure 4 ), in the combination of the flange 208 and the anchor ring 202 Figure 5 , or in the anchor ring 202 Figure 6 .

[0049] Further, as Figure 6 shown, the inner section depth (ISD) of the inner section 311 can be smaller than the outer section depth (OSD) of the outer section 312. This applies to all embodiments described herein.

[0050] Even though different faces are referred to herein as engagement surfaces, this should not be understood as that the holding element 206 is in contact with the said surfaces at all times, but rather that the said surfaces are provided adjacent to the holding element 206 when required by the conditions to hold the holding element 206 in place, i.e. to hold the holding element 206 within the first and second grooves 218, 232.

[0051] Figure 7is a flowchart comprising steps of a method 700 for heat treating a food product FP. The method can be performed with the tubular heat exchanger 100. In a first step 702 of the method, the food product FP is fed from the connection pipe 304 through the coupling device 1 described above into the tube bundle 110 of the tubular heat exchanger 100. In a second step 704, the food product FP can be conveyed through the tube bundle 110. In a third step 706, the heat transfer medium HTM can be heated. In a fourth step 708, which can occur simultaneously with the second step 704, the heat transfer medium HTM can be fed into the casing 302 surrounding the tube bundle 110, thereby heating the food product FP to reduce the microorganisms in the food product FP, i.e. to reduce the number of microorganisms in the food product FP, which otherwise can cause health problems for consumers. The pressure P inside the tube bundle 110 can be higher than 200 bar, while the pressure P' inside the casing 302 can be lower than 30 bar.

[0052] From the above description it is manifest that various embodiments can be made of the application, although only a few have been described and shown. However, all details can be implemented other than those specifically set forth in the above description and in the following claims, without departing from the scope of the subject matter defined in the following claims.

Claims

1. A coupling device (1) for a tubular heat exchanger (100), the tubular heat exchanger (100) comprising a housing (302) configured to surround a tube bundle (110) and a heat transfer medium (HTM), the coupling device (1) comprising: Tube sheet (112), which is configured to be attached to tube bundle (110); A first groove (218) is formed in the surface (220) of the tube sheet (112); A flange (208) is configured to receive the end section (214) of the tube sheet (112) and is provided with holes (226) for receiving fastening devices (306a, 306b). An anchoring ring (202) is provided to be placed around the tube sheet (112) and is provided with holes (210) for receiving the fastening devices (306a, 306b) to be connected to the flange (208); A retaining element (206) comprising an inner segment (311) and an outer segment (312), wherein the inner segment (311) is configured to be placed in the first groove (218) of the tube sheet (112), wherein the retaining element (206) further comprises a first portion (222) and a second portion (224), and The second groove (232) is formed by the combination of the flange (208) and the anchoring ring (202) and is configured to receive the outer segment (312) of the retaining element (206); The tube sheet (112) includes a first O-ring groove (228) and a second O-ring groove (230), wherein the first O-ring (308a) is provided in the first O-ring groove (228) and the second O-ring (308b) is provided in the second O-ring groove (230); The tube sheet (112) has an end section (214) arranged to be insertable into the flange (208) and a top section (216) surrounded by the housing (302), wherein the first O-ring groove (228) and the second O-ring groove (230) are located in the top section (216).

2. The connecting device (1) according to claim 1, wherein, The first portion (222) and the second portion (224) of the retaining element (206) each have a semi-circular shape.

3. The connecting device (1) according to claim 1 or 2, wherein, At least one of the flange (208) and the anchoring ring (202) is provided with a radial retaining element engagement surface (313) for preventing radial movement of the retaining element (206) when the anchoring ring (202) is connected to the flange (208).

4. The connecting device (1) according to claim 1 or 2, wherein, The flange (208) is provided with a radial tube sheet engagement surface (316) and an axial tube sheet engagement surface (318) configured to face the tube sheet (112).

5. The connecting device (1) according to claim 4, wherein, The flange (208) is provided with a sealing groove (309) which is configured to receive a seal (310), wherein the axial tube sheet mating surface (318) is configured to prevent the tube sheet (112) from moving in the axial direction (A), thereby reducing the force (F) exerted by the tube sheet (112) on the seal (310).

6. The connecting device (1) according to claim 1 or 2, wherein, The outer segment depth (OSD) of the outer segment (312) of the retaining element (206) is greater than the inner segment depth (ISD) of the inner segment (311).

7. The connecting device (1) according to claim 1 or 2, wherein, The fastening devices (306a, 306b) and the holes (210) of the anchoring ring (202) are threaded and are configured to interact to connect the anchoring ring (202) to the flange (208).

8. A tubular heat exchanger (100) comprising: The connecting device (1) according to any one of claims 1 to 7, A tube bundle (110) comprising a plurality of tubes connected to a tube sheet (112) and configured to convey food (FP), and A housing (302) is configured to surround the tube bundle (110) and the heat transfer medium (HTM), and Pipe (304) is connected to the flange (208).

9. A method (700) for heat-treating food (FP) using a tubular heat exchanger according to claim 8, wherein the food has a viscosity greater than 100 cP at a temperature of 40°C, the method comprising: The food (FP) is fed from the pipe (304) through the connecting device (1) into the tube bundle (110) via the pipe (304); The food (FP) is conveyed (704) through the tube bundle (110); Heating (706) heat transfer medium (HTM), and The heat transfer medium (HTM) is fed (708) into the housing (302) to heat the food (FP) to reduce microorganisms in the food (FP).

10. The method according to claim 9, wherein the pressure (P) inside the tube bundle (110) is higher than 200 bar.

11. The method according to claim 9 or 10, wherein, The pressure (P') inside the outer casing (302) is less than 30 bar.

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