AU2019207867A1

AU2019207867A1 - Tubular heat exchanger having corrosion protection

Info

Publication number: AU2019207867A1
Application number: AU2019207867A
Authority: AU
Inventors: Sayyed Ahmad FANI YAZDI; Axel Schulze
Original assignee: Hugo Petersen GmbH
Current assignee: Hugo Petersen GmbH
Priority date: 2018-01-12
Filing date: 2019-01-11
Publication date: 2020-07-02
Anticipated expiration: 2039-01-11
Also published as: AU2019207867B2; EP3737904B1; ES2910428T3; CL2020001809A1; WO2019138065A1; MX2020007347A; PE20210061A1; EP3737904A1; DE202018100156U1; BR112020012404A2; MA51562A; KR102561192B1; KR20200107946A

Abstract

The aim of the invention is to reduce corrosion of the pipes in particular in sulphuric acid production. This aim is achieved, according to the invention, by means of a tubular heat exchanger (1) in which the arrangement of the tubes (20) in the tube bundle (2) defines a tube area, which has a tube-free channel (23) between the outer edge of the tube bundle (2) and the lateral surface (41) thereof, wherein a protective plate (5) is arranged between the tube bundle (2) and the lateral surface (41), covering the tube bundle (2) parallel to the longitudinal axis (43), at least in the region which is opposite the inlet opening (13), and wherein the tube area has at least one empty space (6) which divides the tube bundle (2) in a direction substantially perpendicular to the longitudinal axis (43), wherein an empty space (6) is positioned in particular between the protective plate (5) and the longitudinal axis (43).

Description

SHELL AND TUBE HEAT EXCHANGER WITH CORROSION PROTECTION

The invention relates to a shell and tube heat exchanger with corrosion protection according to claim 1.

Shell and tube heat exchangers are also known as shell-and-tube heat exchangers and are the type of heat exchangers most commonly used in industry. In shell and tube heat exchangers, the heat transfer surface separates a hot from a cold fluid space. One fluid flows through the tubes (tube side), while the other fluid flows around the tubes (shell side). Tube bundles are arranged within the shell and supported in a tube sheet such that the latter forms a barrier in order to avoid mixing of the two fluids that have different temperatures. Deflection segments, also known as baffles, may be employed in order to increase the flow rate in the shell or to increase the frequency of contact of the medium in the shell to the heat transfer surface. In this case, the fluid within the shell has to pass over a longer distance between the inlet and outlet ports.

A shell and tube heat exchanger with radial flow provides for a uniform flow from the central channel radially outwards or from the space between the shell of the heat exchanger and the tube bundle toward the central channel. This provides for lower mechanical strain as well as lower pressure loss within the shell of the heat exchanger in comparison to conventional shell and tube heat exchangers such as a cross-flow heat exchanger. This not only provides freedom in the choice of the orientation of the shell-side inlet and outlet ports, but also allows for a more compact design of the tube bundle.

Such shell and tube heat exchangers have a very wide range of applications and are employed in sulfuric acid synthesis, inter alia. In the production of sulfuric acid, first SO 3 is produced and is then absorbed in dilute sulfuric acid. Subsequently, the sulfuric acid formed during absorption is then diluted with water to the desired concentration.

When using a system for sulfuric acid synthesis according to the double contact process, SO 3

containing gas passes through an intermediate absorption tower. Within this unit the SO 3 gas is absorbed in sulfuric acid. The process gas outlet temperature downstream of this absorption tower can be between 50 °C and 120 °C, preferably 80 °C. The gas temperature has to be re-increased to the ignition temperature of the catalyst in the subsequent contact. This temperature can be different, based on different catalysts. Heat from the feed gas to the intermediate absorption tower, which is recovered using a shell and tube heat exchanger, is supplied from the intermediate absorption tower to the process gas. In this case, entrained sulfuric acid particles come into contact with the tubes through which the employed heating medium flows.

The problem here is that the tubes are exposed to a highly aggressive medium at high temperatures. Therefore, the re-heating is usually accomplished in two stages, first using a smaller heat exchanger that comprises a so-called sacrificial tube bundle, to overheat the process gas, and using a second, larger heat exchanger for the final temperature adjustment. Such a system according to Douglas Louie (from: Handbook of sulfuric acid manufacturing; by Douglas K. Louie; Second Edition, ISBN: 978-0-9738992-0-7; p. 3-55) is illustrated in FIG. 1.

A drawback of such a shell and tube heat exchanger is that when aggressive or corrosive media are introduced, they will contact the tubes directly after entering through the shell-side inlet and will deteriorate them so that the tube bundle has to be replaced by a new one at regular intervals. This implies high expenditures for materials and high costs and, moreover, production is interrupted due to the respective exchange times for the replacement.

FIGS. 2 and 3 illustrate another prior art arrangement in which the tube bundle of a shell and tube heat exchanger is covered by a perforated plate in the vicinity of the gas inlet. This in fact allows to somewhat reduce the contact of the tubes with entering corrosive medium, however, protection of the tubes against corrosion cannot be ensured for extended operation. Furthermore, another problem arises due to the accumulation of condensed corrosive liquid in the lower region of the shell.

An object of the invention is to provide an improved shell and tube heat exchanger. More particularly, it is an object of the invention to reduce corrosion of the tubes, for example when the heat exchanger is used in an application in which process gas including corrosive aerosols from condensate drops or fluid particles enters the shell, in particular in the production of sulfuric acid.

These objects are achieved in a surprisingly simple way with a shell and tube heat exchanger according to claim 1. Advantageous embodiments are specified in the dependent claims.

The invention provides a shell and tube heat exchanger in which a tube bundle comprising a plurality of tubes is arranged within a shell, with the shell and tube heat exchanger being outwardly bounded by a shell wall and having a longitudinal axis running centrally through the shell and comprising an inlet opening that is provided substantially parallel to the longitudinal axis and through which fluid enters the shell substantially perpendicular to the longitudinal axis during operation, wherein the arrangement of the tubes in the tube bundle defines a tube array which includes an outer channel devoid of tubes between the periphery of the tube bundle and the shell wall, wherein according to the invention a protective plate is arranged between the tube bundle and the shell wall so as to cover the tube bundle parallel to the longitudinal axis at least in the area opposite the inlet opening, wherein the tube pattern includes at least one empty space which divides the tube bundle in a direction substantially perpendicular to the longitudinal axis, wherein an empty space is in particular located between the protective plate and the longitudinal axis.

Thus, the invention makes it possible to keep liquid particles entering through the inlet opening away from the tube bundle. In particular, within the scope of the invention, the incoming liquid particles can advantageously be directed around the tube bundle. The invention thus makes it possible to prevent the tube bundle from being expose to corrosion to such an extent that it regularly wears out and has to be replaced by a new one, for example in the synthesis of sulfuric acid. This allows for material and cost savings.

The shell and the protective plate of the heat exchanger are accommodated within the cooling medium and therefore in a lower temperature range. As a result, they are substantially not subjected to corrosion.

The protective plate is in particular shaped so as to conform to the outer shape of the tube bundle. In the case of a tube bundle having a circular cross-sectional contour, the protective plate preferably extends along a circular arc, with a radius greater than or equal to the greatest distance of the outermost tube of the tube array from the longitudinal axis, as seen in a direction radially of the longitudinal axis. So the protective plate may be arranged directly in contact with the tube bundle.

Preferably, in the context of the invention, the protective plate is mounted so as to be decoupled from the tubes. This makes it easier to ensure that the plate is at a low temperature and therefore does not corrode. In further corresponding embodiments, the protective plate has at least one, preferably two spacers, which are configured for arranging the protective plate in the shell and tube heat exchanger relative to the tube bundle and in a defined manner relative to the longitudinal axis thereof. For example, the spacers may be in the form of strips extending radially to the longitudinal axis and being attached to the protective plate in particular near the outer edges thereof, which extend parallel to the longitudinal axis, or may be formed integrally with the protective plate, for example by appropriately bending a sufficiently large-sized plate. The spacers may be connected to at least one tube sheet, for example.

According to the invention it is contemplated that the tube array includes at least one empty space which divides the tube bundle in a direction substantially perpendicular to the longitudinal axis, wherein in particular an empty space is located between the protective plate and the longitudinal axis. The empty space is distinguished by the absence of tubes which would otherwise be present in this space according to the distribution of the tubes in the tube array in areas outside the empty space. Since by virtue of the protective plate, the shell-side fluid flowing around the tubes is initially, after entering through the inlet opening into the shell and tube heat exchanger, directed into the outer channel and around the tube bundle, tubes arranged in this zone would hardly contribute to heat transfer since they are substantially not contacted by the fluid flowing on the shell side. It has therefore proven feasible to dispense with these tubes. This allows to achieve further material and cost savings with the help of the invention.

In order to be able to easily discharge the shell-side flowing fluid from the shell and tube heat exchanger, it is contemplated according to a further embodiment that the shell and tube heat exchanger has an inner channel devoid of tubes around the longitudinal axis. After having flowed around the tubes, the fluid flowing on the shell side can be discharged collectively from the inner channel.

Significant material savings can be achieved if the empty space extends between the outer and inner channels.

According to an advantageous embodiment of the invention, the shell and tube heat exchanger has a single chamber. For example, it may be designed as a module for a multi-part shell and tube heat exchanger by having the outlet for the fluid flowing on the shell side adapted to be connected to the inlet of the downstream shell and tube heat exchanger which is preferably of identical configuration. This allows to connect a plurality of shell and tube heat exchangers in series and thus provides for flexible adaptation to changing requirements for the heat to be transferred.

In order to be able to achieve longer flow paths with the highest possible gradient for heat transfer, the shell and tube heat exchanger of a further embodiment of the invention has two or more, preferably up to twenty chambers around a single tube bundle, with at least one deflection segment for the shell fluid arranged between adjacent chambers. During operation of such a shell and tube heat exchanger, the shell fluid enters the first chamber that includes the protective plate, and a deflection segment is disposed between this chamber and the adjacent chamber. The deflection segment consists of a sheet with a surface perpendicular to the longitudinal axis, corresponding inversely to the tube array, having an inner area cut out or an outer area cut off of this surface. More particularly, the cross-sectional shape of the inner area virtually corresponds to that of the inner channel, and the cross-sectional shape of the outer area virtually corresponds to that of the outer channel.

In the context of the invention, the tube bundle may be arranged concentrically to the longitudinal axis. In a further embodiment of the invention, the tube bundle is arranged eccentrically to the longitudinal axis, whereby an additional option for influencing the flow in the shell is created by the arrangement of the tube bundle.

The invention furthermore provides a tube bundle and a protective plate for a shell and tube heat exchanger described above. Such a tube bundle can be manufactured and marketed separately, as can such a protective plate. The final assembly of the entire heat exchanger may then be accomplished only at the application site, for example, by installation into the shell and mounting of the inlets and outlets to the connections for the connection zone.

Within the tube array, the tubes in the tube bundle may be aligned relative to one another, at least in sections thereof, and/or may be offset from one another at least in sections thereof, and/or may be oriented radially with respect to the longitudinal axis at least in sections thereof. Another possibility within the scope of the invention for arranging the tubes relative to one another is a special variation of an offset arrangement, namely an arrangement of series of tubes positioned one behind the other, as seen from the longitudinal axis, in such a way that the tubes are arranged on a curved path. This arrangement is achieved when a composite wall of tubes is established so that their center points are located on concentric circles around the longitudinal axis.

In a preferred embodiment of this type, the tube bundle of the invention includes at least one area in which the tubes are arranged with their center points located on at least three circles that are concentric to the longitudinal axis in such a way that a line connecting the center points of a tube of one circle and of a tube in the circle with the next larger diameter and further of an adjacent tube of a next circle with a larger diameter gives a curved path. In this way, the invention makes it possible to arrange the tubes in a particularly close packing on adjacent circles, since with an appropriately dimensioned tube spacing the distance between the circles on which the center points of the tubes are arranged can even be chosen to be smaller than the radius of the tubes.

According to a further embodiment of the invention it is contemplated that the tube bundle, as seen radially of the longitudinal axis, comprises at least two tube bundle fractions which differ in the number of tubes per area and/or in the outer diameter of the tubes and/or in the spacing of the tubes to one another and/or in the arrangement of the tubes relative to each other. In this way, the heat exchanging surface area of the shell and tube heat exchanger can be flexibly adapted to different requirements while keeping constant the shell dimensions.

The shell and tube heat exchanger according to the invention can in principle be used for gaseous media as well as for fluids that contain liquid components such as aerosols or wet steam. Due to the relatively large heat exchanging surface area that can be achieved with the invention, the shell and tube heat exchanger can be particularly advantageously applied as a gas gas heat exchanger, that is to say for heat exchange between two substantially gaseous fluids. For example, the shell and tube heat exchanger according to the invention can be used for heat recovery from hot exhaust gas streams. A particular field of application is the use in the context of processes for the synthesis of sulfuric acid (H 2SO 4 ).

The invention will now be explained in more detail by way of exemplary embodiments and with reference to the accompanying drawings. The same and similar components are designated by the same reference numerals, and the features of the different exemplary embodiments can be combined with one another. In the figures:

FIG. 1 shows a schematic longitudinal section through an arrangement comprising a shell and tube heat exchanger according to the prior art; FIG. 2 shows a schematic longitudinal section through an arrangement comprising a shell and tube heat exchanger according to the prior art; FIG. 3 shows a schematic longitudinal section through an arrangement comprising a shell and tube heat exchanger according to the prior art; FIG. 4 shows an open schematic perspective view of a shell and tube heat exchanger according to the invention, which comprises one chamber; FIG. 5 shows a schematic longitudinal section through a shell and tube heat exchanger according to the invention; FIG. 6 shows a schematic longitudinal section through an arrangement with a shell and tube heat exchanger according to the invention; and FIG. 7 shows a schematic longitudinal section through a shell and tube heat exchanger according to another embodiment of the invention.

For illustrating purposes, arrows in the figures partially indicate the flow direction of the shell fluid and of the tube fluid as occurring in principle during operation of the shell and tube heat exchanger of the invention.

The shell and tube heat exchanger 1 is outwardly bounded by a shell wall 41. A tube bundle 2 comprising a plurality of tubes 20 is arranged within the shell 4. For the sake of clarity, only one of these tubes is designated by a reference numeral. The shell and tube heat exchanger 1 defines a longitudinal axis 43 running centrally through the shell 4 and has an inlet opening 13 which is arranged substantially parallel to the longitudinal axis and through which fluid enters the shell 4 substantially perpendicular to the longitudinal axis 43 during operation. This is illustrated in FIGS. 4 and 5 by respective arrows.

The arrangement of the tubes 20 in the tube bundle 2 defines a tube array including an outer channel 23 devoid of tubes 20 between the periphery of the tube bundle 2 and the shell wall 41.

In contrast to the prior art heat exchanger according to the applications illustrated in FIGS. 1, 2 and 3, the heat exchanger 1 according to the invention comprises a protective plate 5 which is arranged so as to partially surround the tube bundle 2. In the embodiment shown in FIG. 4, the protective plate 5 shields the tube bundle 2 in the region opposite the inlet opening 13 against direct contact with the fluid entering through the opening 13. In the illustrated embodiment, the protective plate 5 comprises two spacers 51 near either end thereof. These spacers 51 have a length, measured radially of the longitudinal axis 24 of the tube bundle, which is greater than the greatest distance Dmax of the outermost tube 20 of the tube bundle 2 at least by a sufficient amount so that the protective plate 5 can be fastened around the tube bundle 2.

According to the invention, the tube array furthermore includes an empty space 6 which divides the tube bundle 2 in a direction substantially perpendicular to the longitudinal axis 43. This empty space 6 is located between the protective plate 5 and the longitudinal axis 43.

According to the invention, the tube array may have a radial shape in the simplest case, that is to say it may be circular, as in the examples shown. In particular, the tubes 20 are not arranged over the entire circumference of the circle, but a free gap 6 is left. This gap 6 represents an empty space which is distinguished by the absence of tubes 20 which would otherwise be present in this space according to the distribution of the tubes 20 in the tube array as in areas 25 outside this empty space 6.

In the illustrated embodiment, the longitudinal axis 24 of the tube bundle 2 is offset to the longitudinal axis 43 of the shell 4, so that the tube bundle is arranged eccentrically with respect to the longitudinal axis 43 of the shell and tube heat exchanger 1. Should the tube bundle 2 be arranged concentrically within the shell 4, its longitudinal axis 24 would coincide with the longitudinal axis 43 of the shell. A person skilled in the art will understand the description of the features with respect to the longitudinal axis in a meaningful and appropriate manner on the basis of the respective context on the basis of his or her expert knowledge, even if no further explanations are given.

If a gaseous fluid which is loaded with a liquid laterally enters the shell and tube heat exchanger 1 through the inlet opening 13, this liquid may condense during operation due to cooling. The droplets that are arising are conveyed to the inner surface of the shell wall 41 and will flow down there. As shown in the schematic sectional view of a shell and tube heat exchanger 1 according to the invention in FIG. 5, the liquid accumulates at the bottom during operation and can be discharged through an appropriate outlet 15.

Liquid droplets, for example droplets of acid, introduced with the fluid flowing into the shell will be directed outwards in the flow, as seen in the direction of the longitudinal axis, and will thus be directed toward the inner surface of the shell wall 41. Since due to the circular shape of the shell and the protective plate 5 the fluid flowing through the inlet opening 13 and into the shell and tube heat exchanger 1 of the invention will be directed approximately along a circular path, a cyclone effect is generated. As a result, such liquid drops are separated from the gas stream and will flow off in a film along this inner surface. The liquid is collected at the bottom and can be discharged through the respective outlet or bottom drain 15. In an application in the context of sulfuric acid synthesis, the gas flow through the tubes 20 of the tube bundle 2 is free of drops and carries saturated gas in borderline cases.

In this way, corrosive liquid is separated from the gas stream. Corrosion in the shell wall can be prevented by appropriate selection of the shell material. The shell wall is located at the cold side of the heat exchanger and therefore there are many materials that are corrosion-resistant in this temperature range. In this way, the hot tube walls are kept dry so that they are not subjected to corrosion. Thus, it has been possible to convert a wearing heat exchanger into a long-term durable heat exchanger, thereby eliminating new equipment procurement costs as well as production downtime for the replacement of the wearing heat exchanger. The gases escaping from the shell of these heat exchangers are overheated, so there is no risk of corrosion for the downstream equipment, which in turn allows for a more cost-effective material selection in the downstream equipment.

In a preferred application of the invention, the shell and tube heat exchanger 1 is positioned such that the longitudinal axis 43 lies essentially perpendicular to the direction of gravity, that is to say the heat exchanger 1 is operated with a tube bundle that extends horizontally, so to speak.

Such an application is shown in FIG. 6. Here, the heat exchanger is operated in combination with a second shell and tube heat exchanger which is arranged perpendicular to the shell and tube heat exchanger 1 of the invention. The arrangement of the heat exchangers perpendicular to one another is not mandatory, they may also be arranged on top of one another, for example. In a further embodiment, they may be arranged next to one another as two separate heat exchangers. In a further embodiment, the heat exchanger extending horizontally in the view mentioned above may be arranged vertically and the condensate or separated liquids can be discharged through an annular channel or a trough which is attached to the lower tube sheet.

The use of the shell and tube heat exchanger 1 of the invention in a horizontal orientation provides for easy access and maintenance in unforeseen situations as well as for simple replacement, which can be accomplished quickly and therefore inexpensively.

The heat transfer surface area of the heat exchanger 1 of the invention in the embodiment shown in FIG. 6 is rather small and serves to achieve a temperature differential in a range between 10 K and 50 K, preferably 15 K to 25 K. Therefore, the number of tubes is also rather small, which results in cost savings. The diameter of these few tubes is chosen to be relatively large. The reference parameter for the respective specified parameter is the corresponding dimension in the vertically oriented heat exchanger according to the arrangement shown in FIG. 4. For sulfuric acid synthesis, the system is designed such that the dew point of the sulfuric acid will definitely not be reached at the gas outlet.

The material chosen for the shell and tube heat exchanger according to the invention is a corrosion-resistant stainless steel designed for the respective requirements during operation.

The invention thus provides an optimized fluid flow, in particular an optimized gas flow in the tangential and radial directions with respect to the tube bundle of the heat exchanger. When used in the context of sulfuric acid synthesis, condensing acid can be prevented from accumulating at the connection points of the tubes, since these are aligned vertically.

In the embodiment shown in FIG. 7, a tube bundle is arranged within the shell with an empty space 6 in such a way that the empty space 6 is located in the vicinity of the gas outlet. The protective plate 5 is arranged in the vicinity of the gas inlet upstream of the tubes 20 of the tube bundle 2 as seen in the flow direction. It may have openings provided therein, through which incoming gas is directed between the tubes 20 of the tube bundle. Gas discharge is accomplished in the zone of the empty space 6, that is in the portion of the shell and tube heat exchanger devoid of tubes. For this purpose, the latter has two outlets 15 in the embodiment shown in FIG. 7.

It will be apparent to a person skilled in the art that the invention is not limited to the examples described above, but can rather be varied in various ways. The features of the individually illustrated examples may in particular also be combined or swapped with one another.

List of Reference Numerals

1 Shell and tube heat exchanger 13 Inlet opening, supply for shell fluid, supply means 14 Outlet opening, discharge for shell fluid, discharge means 15 Outlet, bottom drain 2 Tube bundle 20 Tube 21 Innerchannel 23 Outer channel 25 Area of tube array other than the empty space 3 Tube sheet 4 Shell 41 Shell wall 43 Longitudinal axis of shell 5 Protective plate 51 Spacer 6 Empty space, gap Dmax Greatest distance of outermost tube of tube array from the longitudinal axis

Claims

Claims:

1. A shell and tube heat exchanger (1), comprising a tube bundle (2) consisting of a plurality of tubes (20) arranged within a shell (4), which is outwardly bounded by a shell wall (41) and defines a longitudinal axis (43) running centrally through the shell (4) and has an inlet opening (13) which is provided substantially parallel to the longitudinal axis (43) and through which fluid enters the shell substantially perpendicular to the longitudinal axis during operation; wherein the arrangement of the tubes (20) in the tube bundle (2) defines a tube array which includes an outer channel (23) devoid of tubes between the periphery of the tube bundle (2) and the shell wall (41); wherein a protective plate (5) is arranged between the tube bundle (2) and the shell wall (41) so as to cover the tube bundle (2) parallel to the longitudinal axis (43) at least in the area opposite the inlet opening (13); wherein the tube array includes at least one empty space (6) which divides the tube bundle (2) in a direction substantially perpendicular to the longitudinal axis (43), wherein an empty space (6) is located in particular between the protective plate (5) and the longitudinal axis (43).

2. The shell and tube heat exchanger (1) of claim 1, wherein the shell and tube heat exchanger (1) includes an inner channel (21) devoid of tubes (20) around the longitudinal axis.

3. The shell and tube heat exchanger (1) as claimed in any of the preceding claims, wherein the empty space (6) extends between the outer channel (23) and the inner channel (21).

4. The shell and tube heat exchanger (1) as claimed in any of the preceding claims, wherein the shell and tube heat exchanger has a single chamber.

5. The shell and tube heat exchanger (1) as claimed in any of claims 1 to 3, wherein the shell and tube heat exchanger has two or more, preferably up to twenty chambers around a single tube bundle (2), with a deflection segment for the shell fluid arranged between adjacent chambers, and wherein a protective plate (5) is arranged in at least one chamber.

6. The shell and tube heat exchanger (1) as claimed in any of the preceding claims, wherein the tube bundle (2) is arranged concentrically or eccentrically relative to the longitudinal axis (43).

7. The shell and tube heat exchanger (1) as claimed in any of the preceding claims, wherein the tubes (20) in the tube bundle (2) are aligned to one another at least in sections thereof, and/or are offset from one another at least in sections thereof, and/or are oriented radially with respect to the longitudinal axis at least in sections thereof.

8. The shell and tube heat exchanger (1) as claimed in any of the preceding claims, wherein the tube bundle (2) comprises at least two tube bundle fractions as seen radially of the longitudinal axis (43), which differ in the number of tubes (20) per area and/or in the outer diameter of the tubes (20) and/or in the spacing of the tubes (20) to one another and/or in the arrangement of the tubes (20) relative to each other.

9. A tube bundle (2) for a shell and tube heat exchanger (1) as claimed in any of claims 1 to 8.

10. A protective plate (5) for a shell and tube heat exchanger (1) according to claims 1 to 8 or for a tube bundle (2) according to claim 9.

11. Use of a shell and tube heat exchanger (1) as claimed in any of claims 1 to 8 as a gas-gas heat exchanger, in particular for heat recovery.

12. Use of a shell and tube heat exchanger (1) as claimed in any of claims 1 to 8 as a gas-gas heat exchanger, in particular for heat recovery, wherein the gas-gas heat exchanger is used in a process for sulfuric acid synthesis.

Prior Art

shellside outlet

tubeside inlet

shellside inlet 1/7

tubeside outlet

sacrificial tube bundle Fig. 1

Prior art 2/7

Fig. 2

Prior art 3/7

Fig. 3

4 13 41

51 23 2 5 20 4/7

Dmax 6

25

43 51

24 to 14 15 Fig. 4

1 5 3

41 51 6 51 5/7

20 21

15 Fig. 5

1 13 6/7

14 Fig. 6

13 5

1 51 51 4 41

20 7/7

21

6 15

6

Fig. 7