AU631418B2

AU631418B2 - Heat exchanger

Info

Publication number: AU631418B2
Application number: AU53837/90A
Authority: AU
Inventors: Helmut Kreis; Dieter Mihailowitsch; Manfred Steinbauer
Original assignee: Linde GmbH
Current assignee: Linde GmbH
Priority date: 1989-04-25
Filing date: 1990-04-24
Publication date: 1992-11-26
Anticipated expiration: 2010-04-24
Also published as: DE59004850D1; DD300656A5; NO173352B; EP0394758A3; EP0394758B1; AU5383790A; NO901810L; CZ204590A3; EP0394758A2; NO173352C; DE3913579A1; NO901810D0; ZA903091B

Description

-M 017460 240490 Insert place arnd date c Signature of declar att-ttioflrequired) Noce, Initial all COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION NAME ADDRESS OF APPLICANT: The p st ant sing direc and c anoth~ the f: of op lattei at a tac a, .p 9 4 o 4 9 99 a a pa aa a.

a a a a a 94 at 9t4 Linde Aktiengesellschaft Abraham-Lincoln-Strasse 21 D-6200 Wiesbaden Federal Republic of Germany NAME(S) OF INVENTOR(S): Manfred STEINBAUER Dieter MIHAILOWITSCH Helmut KREIS a 6 ADDRESS FOR SERICE: a9t~ a aatI 9999 P 09 Os C DAVIES COLLISON Patent Attorneys I Little Collins Street, Melbourne, 3000.

Heat for c excha f low which exits 099 into pipes.

ber f the i f luid throug passatg open fow COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED: Heat exchanger 99,'.

9-499 99 9 9 09 a $4 The following statement is a full description of this invention, including the best method of performing it known to me/us:- This device with hr tion, charnbe solved

I

13 Jz -Y ouleer DAVIES ('OLLISON. MELBOURNE and CANBERRA. I la The present invention relates to a heat exchanger having a substantially cylindrical flow chamber defined by a jacket, comprising a plurality of tubes extending through the flow chamber in a direction which is substantially parallel to the cylinder axis and comprising at least one pair of pipes arranged opposite one another at the cylinder surface of the jacket and leading into the flow chamber. Furthermore, the invention relates to a method ae of operating a heat exchanger of this type, to the use of the o latter and to the implementation of the method.

exchange. Thus, a fluid enters through one of the pipes into the Saflow chamber where it flows around the tubes in a flow direction exits through another pipe. The flow chamber is often divided S into several sections, each with its own pair ofby inlet and outlet o° pipes. Such a construction, in which the fluid in the flow chamber flows transversely to a second fluid which is passed through the interior of the tubes, offent ers throughe advantage that the first fluid suffers only a very small pressure loss upon passing flthrough the heat exchanger This is due to a relatively direct Sexitpassage through the flow chamber which, however, requires a truly o° open construction without any built-in elements obstructing the flow in the flow chamber.

This in turn reduces the mechanical strength and rigidity of the first device, so that hitherto such heat exchangers could onis due to a relatively be used with relatively low flow velocities in the flow chamber. In addition, the problem of distributing the first fluid in the flow chamber perpendicularly to the direction of flow has not yet been solved satisfactorily in such transverse flow heat exchangers.

I;-

-r~ -2- According to the present invention there is provided a heat exchanger having a substantially cylindrical flow chamber defined by a jacket, the heat exchanger comprising: a plurality of tubes extending through the flow chamnber in a direction which is substantially parallel to the cylinder axis; a pair of inflow/outflow pipes arranged opposite one another at the cylindrical surface of the jacket and leading into the flow chamber; a support plate disposed in the flow chamber substantially at right angles to the cylinder axis; and an anti-noise plate arranged in the flow chamber substantially parallel to the cylinder axis, wherein the anti-noise plate and the support plate are connected to each other.

Preferably, the heat exchanger comprises more than one pair of inflow/outflow pipes and/or more than one support plate and/or more than one anti-noise plate.

The or each support plate results in a considerably more stable and rigid mechanical construction and reinforces the rigidity of the cylindrical jacket enclosing the flow chamber. Thus, embodiments of the heat exchanger according to the present invention are capable of handling flow velocities of up to about 20 10% of sound velocity in the flow chamber.

0 The heat exchanger may also be subject to problems due to acoustic vibrations developing as a result of standing waves in planes perpendicular to the cylinder .o axis. An anti-noise plate arranged in the flow chamber substantially parallel to the cylinder axis tends to reduce these problems. A parallel anti-noise plate extending over the full length of the flow chamber may be used on each side of the cylinder axis. Depending on the conditions, an odd number and an asymmetrical arrangement of anti-noise plates may also be favourable. In this manner, obstacles are build into each cross-sectional surface which counter the formation of standing acoustic waves, The connection of the anti-noise plates and the support plates, for example by 920910,GSR5L a001,53837.spe,2 -3 welding of the contact surfaces, further enhances the stability of the heat exchanger and facilitates its production. This results in a particularly stable and rigid honeycomb structure inside the flow chamber.

Admittedly, a transverse exchange of the fluid in the flow chamber between different honeycombs is no longer possible with this construction, so that a uniform distribution of fluid is not automatically ensured. Especially the exchange between the region divided into honeycombs and the peripheral region of the flow chamber is strongly impeded, so that the heat exchange performance particularly in this peripheral region is not optimal.

It is preferable that a space be provided between the longitudinal sides of the or each baffle plate and the jacket.

Compared to previously proposed baffle plates which are provided only over a small area below the inlet pipe and which therefore constitute only a rough measure to distribute the fluid flowing through the inlet pipe, the or each baffle plate according to embodiments of the present invention specifically results in an improved supply of fluid to the peripheral regions of the flow chamber.

S20 B O Furthermore, it is preferable that the or each baffle plate be divided in the direction of the cylinder axis into sections having different relative aperture areas.

As a result, a specific distribution of the fluid passed through the flow chamber can be achieved, also in the direction of the cylinder axis.

In this respect it is advantageous that the or each baffle plate be divided into segments each having an integral number n of sections and be bounded on each side either by one end of the flow chamber or by a plane lying perpendicular to the cylinder axis midway between two pairs of pipes. The pipes are preferably arranged such that the segments are equal in size. A heat exchanger may have a plurality of segments or only a single one. In the latter case only one pair uf pipes is provided.

920910,GSRSPE.001,53837.spe,3 4 In a -fvrurable further development of the invention, each segor ecC 1ment of the [baffle plate has an even number n of successive sections Pi, i while in each case the sections P. and P i ,n/2 I n-i+l are constructed in identical manner as regards their dimensions a b. and their relative aperture area L..

I 1 1 Thus, the segment or segments are symmetrical, as regards their division into sections, to the connecting line of the associated pair of pipes.

S It is expedient when the number n of sections P. within a segment 1 ranges between 2 and 18 and when the following relationship S applies for the relative aperture areas L. of the sections P.:

L

i Li+

I

i SPreferably, n ranges between 4 and 8.

In a faeurable embodiment of the invention, the ratio between tl Slargest and smallest relative aperture area LI/L is selected as a function of the distribution length 1 distance between v central axis of the inlet pipe and boundary of the corresponding segment) and of the inner radius r of the inlet pipe, and this preferably according to the relationship

L

1 =f n/2 The factor f is of the order of 1, for example between 0.8 and 1.3. The ratio 1 /r is usually of the order of 3; L /Ln 2 is generally between 1.5 and 2.0, preferably about 1.7.

Extensive hydrodynamic computations have shown that, with the aid of such a design of the baffle plate, it is possible to achieve a favourable distribution of gas passed through the flow chamber 53837/90 and thereby a high heat exchange performance of the heat exchanger. A range of valves 6f Ln/ 2 of between 10 and 30% has proved to be particularly favourable.

According to a further variant of the heat exchanger, the tubes extending through the flow chamber are combined into several bunches arranged in rows along the connecting axis of a pair of pipes, the tubes being connected to one another in such a manner that the bunches are flowed through successively by the fluid flowing through the tubes. In this manner it is additionally possible as a function of the manner of operation to obtain a. parallel current or countercurrent effect.

The invention also relates to a method of operating a heat exchanger of the type as herein described, with each pair of pipes consisting of an inlet pipe and an outlet pipe, in which a first fluid is introduced into the flow chamber through the inlet pipe(s) and discharged through the outlet pipe(s) and a second fluid is passed through the interior of the tubes. The second fluid is first introduced into the tubes of the bunch nearest to the outlet pipe and then flows successively 2 second fluid is thus, to a certain extent, guided in counter-current to the first fluid.

1 In a preferred development of the method, the first fluid is introduced into the flow chamber in gaseous form and is partly condensed during the heat exchange with the second fluid.

Preferably, water is used as the second fluid and is utilized as a cooling or heating medium.

rI4*44 4*4*44 920910,GSRSPE.001,53837.spc,5 L, 6 Until some 15 years ago, it was usual to use heat exchangers as fission gas coolers in ethylene plants which, similar to the typea.r. ing-to the invention, have a cylindrical flow chamber and cooling water tubes arranged parallel to the cylinder axis, but in which the gas to be cooled is passed to and fro several times over the cross-section of the flow chamber.

However, this results in a substantially greater pressure loss and the process becomes overall uneconomical with respect to o energy.

When energy became in short supply and expensive, it became 0 00 oC00 necessary to use direct contact coolers and to cool the fission gas by direct heat exchange with water. Admittedly, such instalo lations suffer limited pressure loss; however, this is achieved at the price of high expenditure on apparatus. This is due, on the one hand, to the fact that the cooling water must be circulated and therefore has to be cooled again in a separate heat oo. .exchanger. On the oth nr hand, it is necessary to separate the oo water derived from the direct contact cooler from heavy hydroo carbons which have condensed out in a separator.

i c4S op pre-seA The use of the heat exchanger according to 4- invention as a stepped cooler for fission gas in an ethylene plant, and the o implementation of the method according to the invention for cool- 0 ing fission gas in a process for the production of ethylene now o combine the advantages of the two types of fission gas coolers known in ethylene plants, namely, on the one hand, moderate expenditure on apparatus and thus relatively low capital costs and, on the other hand, very small pressure loss and thus low operating costs. Preferably, the fission gas is passed through the flow chamber as the first fluid.

The invention and further details of the invention will be explained more specifically hereinbelow with referenc- to an exemplified embodiment which is diagrammatically illustrated in the drawings.

7 In the drawings: Fig. 1 shows a longitudinal section in a vertical plane, Fig. 2 shows a cross-section and Fig. 3 shows another longitudinal section in a horizontal plane through a heat exchanger according to the invention.

The jacket 1 of the heat exchanger is substantially formed cylin- S der-symmetrically about the axis 8. Together with the partition walls 3A and 3C it encloses the flow chamber 2. The latter in I i turn is divided by a further partition wall 3B into two part S chambers between which no gas exchange is possible. Associated with the part chamber shown on the left-hand side in Fig. 1 is a first pair 4 of pipes constituted by inl2t pipe 4A and outlet pipe 4B. Similarly, the pipes 5A and 5B of the pair 5 can be seen on the right-hand side.

According to the invention, support plates 12 are built into the flow chamber 2, the total number of which in the embodiment shown o° is 10, i.e. 5 per part chamber. The support plates 12 are carried by a bottom 15. Furthermore, Fig. 2 shows two antinoise plates 11 which extend over the full length of the flow chamber 2 from partition wall 3A to partition wall 3C (see Fig. Support plates S 12, antinoise plates 11 and partition walls 3A, 3B, 3C are welded o together and form a rigid honeycomb structure in which no lateral gas exchange between the honeycombs and no exchange to the volumes between the antinoise plates 11 and the jacket 1 is s possible.

For this reason, according to the invention, there is provided a baffle plate 10 which is arranged below the inlet pipes 4A, 5A in a horizontal plane over the full length of the flow chamber 2.

The width b of the baffle plate 10 shown in Fig. Xkis approximately equal to the inner diameter 2r of the inlet pipes 4A, j-9 8 However, b may also be slightly larger or smaller than 2r (see +kethe numerical example below) In~transverse direction) the baf fle plate 10 is bounded by the two antinoise plates 11 and is integrally connected with the latter.

As a result of this arrangement, the apertured baffle plate impedes the passage of the fluid introduced through the inlet pipes 4A, 5A into the central part of the f low chamber 2 and thus effects a better distribution through the interspaces 14 (see Fig. 2) in the direction of the peripheral volume between the antinoise plates 11 and the jacket 1.

00 00 0 0*0 00 o~ 00 0 O 0 0 00 00 0 0 00 00:00 In similar fashion to the part chambers of the flow chamber 2, a -3 the baffle plate 10 is divided into two segments by the partition a 00 wall 3B. Each of the two segments of the baffle plate 10 consists of ecion P1 to6 an '1 tP,6 respectively, as is shown in Fig. 3. The number n of sections per segment is 6 in the embodiment shown. In a particular version, the baffle plate 10 has three different kinds of apertures which are characterized by 000 different relative aperture areas. By relative aperture areas is meant the ratio between the opening area of the apertures and the 0000overall surface area of the plate. The different kinds of apertures can be obtained by different densities and/or dimensions of apertures.

0% 0 0 '040 Preferably, in the embodiment shown, three different valuesLi L 2 L 3 of relative aperture areas are used, namely L1for Pit P 6 1 Pill P1 6 L2for P 2

P

5

P'

2

P'

5 and L3for P 3 1 P 4 1 Pt3' P' 4 The apertures are selected such that the relative aperture area (L 3 is smallest directly below the inlet pipes 4A, 5A and the relative aperture area L1is largest at the sections furthest removed from the inlet pipes 4A, 5A, so as to obtain a very uniform fluid distribution in the flow chamber along the cylinder '7 ais 9 In a heat exchanger constructed for testing purposes, the following numerical values were selected: Diameter of the flow chamber d 1676 mm s Radius of the opening of the inlet pipe r 348 mm Distribution length 1 999 mm v Length of each section a 333 mm Width of the sections b 666 mm Relative aperture areas: L 1 40 S2 30

L

3 23 o Ratio max. to min. relative o 0 o aperture area: LI/L 1.74 oAperture diameters: d 8 mm 1 o d 2 8 mm 0t. d 3 10 mm Aperture distribution: t 12 mm t 2 14 mm t 3 20 mm S From a manufacturing point of view, it is favourable to select the length a of the sections P 1 to P 6 and P' to P' respectively tO1 61 6 petey to be equal to the distance between two support plates 12. From a S distributing point of view, of course, a larger number of sections with different relative aperture areas is more favourable; in the hydrodynamic computations, a value range for the number n of sections per segment of from 2 to 18, preferably from 4 to 8 So has proved to be a practicable compromise between distribution quality and expenditure on apparatus.

The tubes extending through the flow chamber 2 have not been shown explicitly in the drawings. In the longitudinal sectional view of Fig. 1, their straight segments are situated between the baffle plate 10 and the carrier plate 15. At the ends of the heat exchanger, the tubes are connected either to one of the pipes 6A, 6B or to each other, as will be explained in further detail hereinbelow with reference to Fig. 2.

(A

A

:if In the cross-sectional view, 4 bunches A 1 2 to A 7 8 are shown, which are each divided into two subgroups A 1

A

2 to A 7

A

8 The subgroups consist of 50 to 300, preferably 120 to 250 tubes and each occupy a volume marked by two crossed lines on either side of an anti-noise plate 11.

The tubes are connected to one another in such a manner that a fluid which is fed in through the pipe 6A first flows parallel through the tubes of subgroups A 1 and is then passed successively through the tubes of the other subgroups and bunches in the sequence A 2

A

3

A

4

A

6

A

7

A

8 and subsequently to the outlet pipe 6B.

In the method according to the invention, the heat exchanger is operated such that a first fluid for example fission gas in an ethylen.; plant is introduced into the flow chamber 2 in two parallel streams through the inet pipes 4A and 5A and is discharged through the outlet pipes 4B, 5B, and is indicated by arrows in Figs.

1 and 2. In transverse flow thereto, a second fluid for example cooling water is introduced through the pipe 6A, passed through the tubes (not shown) and discharged through the pipe 6B (arrows 7 in Fig. 1).

20 Embodiments of the present invention provide a heat exchanger of the aforementioned kind having an improved mechanical strength even at higher flow velocities. A favourable heat exchange performance and a good distribution of the first fluid in the flow chamber is also provided.

Oo 04 0 0 0* 0 00o :'h 920910,GSRSPF 0 001,53837spe,

Claims

1. A heat exchanger having a substantially cylindrical flow chamber defined by a jacket, the heat exchanger comprising: a plurality of tubes extending through the flow chamber in a direction which is substantially parallel to the cylinder axis; a pair of inflow/outflow pipes arranged opposite one i 10 another at the cylindrical surface of the jacket and leading into the flow chamber; a support plate disposed in the flow chamber substantially at right angles to the cylinder axis; and an anti-noise plate arranged in the flow chamber substantially parallel to the cylinder axis, wherein the anti-noise plate and the support plate are connected to each other.

2. A heat exchanger according to claim i, wherein a :9o baffle plate is arranged substantially perpendicular to a line defined between the pair of opposing inflow/outflow Ia pipes and extends over the full length of the flow chamber parallel to the cylinder axis. S" 4:

3. A heat exchanger according to claim 1 or claim 2, wherein the heat exchanger comprises more than one pair piof inflow/outflow pipes and/or more than one support plate and/or more than one anti-noise plate. o 49

4. A heat exchanger according to claim 2 or claim 3, wherein a space is provided between the longitudinal sides of the or each baffle plate and the jacket. S92O910,GSRSPEhoe1,53837.sp, 1 K: -12- A heat exchanger according to any one of claims 2 to 4, wherein the or each baffle plate is divided in the direction of the cylinder axis into sections having different relative aperture areas.

6. A heat exchanger according to claim 5, wherein the or each baffle plate is divided into segments each ha ,ng an integral number n of sections and being bounded on each side either by one end of the flow chamber or by a plane lying perpendicular to the cylinder axis mid-way between two pairs of pipes.

7. A heat exchanger according to claim 6, wherein each segment of the or each baffle plate has an even number n of successive sections Pi, i 1, while in each case the sections Pi and Pn 1 i are constructed in identical manner as regards their dimensions aj, b i and their relative aperture area L.

8. A heat exchanger according to claim 7, wherein the number n of sections Pi within a segment ranges between 2 and 18 and that the following relationship applies for the relative aperture areas L, of the sections Pi: 25 LI Li i 9S A heat exchanger according to claim 8, wherein the following relationship applies for the maximum relative aperture area LI: LI f /l/r Ln, with f: factor, 0.8 f 5 1.3 distribution length distance between connecting axis of a pair of pipes and boundary of corresponding segment) r: radius of the opening of the inlet pipe 4 4 4 o9 4 4 4 4 44;* 4 4 49 4 4 4 4 44 4 4r 920910,GSRSPa00 1,53837.spe, 12 ~LFZi17--nl~ I I I~ ~~~~rrPau\ru~i~i I ;I*c*uaan

13- A heat exchanger according to any one of the preceding claims, wherein the tubes are combined into several bunches arranged in rows along the connecting axis of a pair of pipes, the tubes being connected to one another in such a manner that the bunches are flowed through successively by the fluid flowing through the tubes. 11. A method of operating a heat exchanger as defined in claim 10, with the or each pair of the inflow/outflow pipes consisting of an inlet pipe and an outlet pipe, wherein a first fluid is introduced into the flow chamber through the inlet pipe(s) and discharged through the outlet pipe(s) and a second fluid is passed through the interior of th tubes, and wherein the second fluid is first introduced into the tubes of the bunch nearest to the outlet pipe and then flows successively through the tubes of the bunches arranged further toward the inlet pipe. 12. A method according to claim 11, wherein the first :fluid is introduced into the flow chamber in gaseous form 25 and is partly condensed during heat exchange with the second fluid. t l 13. A method according to claim 11 or 12, wherein water is used as the second fluid.

14. Use of a heat exchanger according to any one of claims 1 to 9 as a stepped cooler for fission gas in an ethylene plant. 920910,GSRSPE00 1,S3837pe13 14 Implementation of the method according to any one of claims -11 to 13 for cooling fission gas in a process for the production of ethylene.

16. A heat exchanger substantially as hereinbefore described with reference to the drawings.

17. A method of operating a heat exchanger substantially as hereinbefore described with reference to the drawings. DATED this 10th day ofSetm 19 LINDE AKTIENGESELLSCHAFT By Its Patent Attorneyp, DAVIES COLLISON CAVE 9209 1 O.GSRSPE,00 1,53837,spe, 14