GB2100851A

GB2100851A - Heat exchanger

Info

Publication number: GB2100851A
Application number: GB08119137A
Authority: GB
Inventors: Leenderd Taal
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 1981-06-22
Filing date: 1981-06-22
Publication date: 1983-01-06
Also published as: AU8505982A; EP0068529A1; JPS588998A; ES8308049A1; ES513295A0

Description

1

GB 2 100 851 A 1

SPECIFICATION Heat exchanger

The invention relates to a heat exchanger provided with a series of heat exchange tubes, 5 wherein the one medium flows around the tubes and the other, heat exchanging medium is passed through the tubes. Heat exchangers of the above so-called closed type are widely used in the industry, for example in the oil process industry for 10 cooling products from hydrocracking installations.

The present invention relates more in particular to a heat exchanger which is suitable for the application of gas/liquid mixtures as heat exchanging media.

15 When in the known heat exchangers a gas/liquid mixture is applied as heat exchanging medium frequently deterioration of the heat exchange tubes and/or other parts of the heat exchanger occurs. It has been found that such a 20 deterioration is caused by a maldistribution of the mixture over the heat exchange tubes. The problems occurring at maldistribution of the mixture over the heat exchange tubes may originate from the differences in heat exchange 25 properties of gas and liquid. Liquid has a much better heat exchange rate than gas. Therefore in case a high temperature gas/liquid mixture is cooled by passing the mixture through heat exchange tubes surrounded by a low temperature 30 fluid a heat exchange tube receiving much liquid and only a small quantity of gas, will cool down more rapidly and to a greater extent than a heat exchange tube receiving only a small quantity of liquid and relatively much gas. The resulting 35 temperature differences between the heat exchange tubes in the known heat exchangers, may cause excessive stresses. Such stresses may easily result in damage to the heat exchange tubes and other parts of the heat exchanger. 40 The problems occurring at maldistribution of a gas/liquid mixture over the heat exchange tubes of a heat exchanger may also originate from the composition of the gas. When a high temperature gas contains dissolved corrosive matter, the 45 corrosive matter will come free upon lowering of the temperature of the gas. This for example occurs upon cooling down gaseous reactor effluents containing corrosive ammonium salts. To absorb such corrosive matter, liquid is supplied to 50 the gas prior to cooling down.

It has been found that when such a gas mixed with liquid to absorb the corrosive matter is cooled down by passing the gas through the heat exchange tubes of a known heat exchanger, some 55 of the heat exchange tubes are damaged by corrosion, due to maldistribution of the liquid over the heat exchange, tubes. Insufficient liquid has reached these tubes to absorb the corrosive matter and/or to wash the corrosive matter from 60 the tube walls.

From the above it will be clear that gas/liquid mixtures applied as heat exchanging media should be distributed as uniformly as possible over the heat exchange tubes, to avoid deterioration of

65 these tubes.

The object of the present invention is to improve the known heat exchanger provided with a series of heat exchange tubes in such a manner that when a gas/liquid mixture is supplied for 70 passing through the heat exchange tubes a uniform distribution of the mixture over the heat exchange tubes is obtained.

The heat exchanger according to the invention provided with a series of heat exchange tubes, 75 thereto comprises a separator chamber, a supply for a gas/liquid mixture to the separator chamber, a series of conduits, each conduit forming a fluid communication between the separator chamber and a corresponding heat exchange tube, at least 80 one.gutterfor collecting liquid extending along the series of conduits, and means for causing liquid from the gutter to flow to each gasstream passing through the corresponding conduit.

The invention will now be described by way of 85 example in more detail with reference to the accompanying drawings, wherein:

Figure 1 shows a cross section of a part of a heat exchanger in accordance with the invention;

Figure 2 shows a topview of the part of the heat 90 exchanger shown in Figure 1;

Figure 3 shows a cross section of a first alternative embodiment in accordance with the invention;

Figure 4 shows cross section IV—IV of 95 Figure 3;

Figure 5 shows a cross section of a second alternative embodiment in accordance with the invention; and

Figure 6 shows cross section VI—VI of 100 Figure 5.

In the embodiment of the invention shown in Figures 1 and 2, a heat exchanger, indicated by reference numeral 1 comprises an elongated, horizontally extending vessel 2, for the supply of 105 fluid to a series of heat exchange tubes 3 arranged along the length of the vessel 2.

Fluid passed through said heat exchange tubes 3 is collected in a not shown collecting vessel of the heat exchanger 1.

' 10 The elongated vessel 2 is provided with an inlet 4, for the supply of fluid into a separator chamber 5 formed by the vessel 2. In said separator chamber 5 the fluid supplied via the inlet 4 is divided over the various heat exchange tubes 3 by 115 means of a series of conduits 6, each conduit 6 forming a fluid communication between the separator chamber 5 and one heat exchange tube 3. The conduits 6 being mounted in openings of the vessel 2 are secured to the vessel 2 and the 120 heat exchange tubes 3 by means of welds.

The upper ends of the conduits 6 are arranged at a level above the bottom of the separator chamber 5, so that gutters 7 and 8 extending along the conduits 6 are formed in which gutters 125 liquid can be collected. The wall of each of the conduits 6 is provided with a number of slots 9 for discharging liquid from said gutters 7 and 8. The lower ends of the slots 9 in the walls of the conduits 6^are arranged at substantially the same

2

GB 2 100 851 A 2

level.

During operation a gas/liquid mixture to be cooled is supplied to the heat exchanger via the inlet 4. In the separator chamber 5 the liquid from 5 the gas/liquid mixture will collect in the gutters 7 and 8 and form a layer of liquid over the full length of the gutters 7 and 8.

The gas in the gas/liquid mixture passes through the conduits 6 via the open ends thereof 10 and enters into the heat exchange tubes 3. When the liquid level in the gutters 7 and 8 has reached the lower ends of the slots 9 the liquid will flow via said slots 9 into the conduits 6, where it is mixed with the gas passing through said conduits 6, so 15 that mixtures of liquid and gas will flow into the heat exchange tubes 3. By the arrangement of the gutters 7 and 8 in combination with the conduits 6 provided with the slots 9, liquid and gas are equally distributed over the heat exchange 20 tubes 3.

Reference is now made to Figures 3 and 4 showing a first alternative of the embodiment shown in the Figures 1 and 2.

The part of the heat exchanger shown in these 25 Figures comprises an elongated vessel 10

enclosing a separator chamber 11. A plurality of inlets 12 are provided for supplying a gas/liquid mixture into the separator chamber 11. For the sake of simplicity only one inlet 12 has been 30 shown in Figure 2. A series of heat exchange tubes 13 extends along the length of the vessel 10 and are arranged in openings of a structure 14, for example a forced piece, forming the bottom part of the vessel 10. For inspection and maintenance 35 of the heat exchange tubes 13 removable plugs 1 5 are arranged in the forced piece 14 opposite of said tubes 13. A series of conduits 16 are arranged along the length of the vessel 10 each conduit 16 forming a fluid communication 40 between the separator chamber 11 and a heat exchange tube 13.

Two substantially parallel gutters 17 and 18, for collecting liquid supplied via the inlets 12, extend along the conduits 16. Liquid can be 45 discharged from said gutters 1 7 and 18 via a plurality of sets of liquid conduits 19 and 20 arranged in the structure 14. Each set of liquid conduits 19 and 20 forms a fluid communication between the gutters 17 and 18 and the interior of 50 an enlarged part 21 in a conduit 1 6.

The enlarged parts 21 of the conduits 1 6 are interconnected thereby forming a chamber extending along the series of heat exchange tubes 13. The separator chamber 11 is further provided 55 with baffles 22 arranged in front of the inlets 12 for dividing the incoming fluid flows over the length of the separator chamber 11.

During operation a gas/liquid mixture is supplied into the separator chamber 11 via the 60 inlets 12. Due to the presence of the baffles 22 the incoming fluid flows are divided over the separator chamber 11 and cannot pass directly through the conduits 16 arranged opposite of the ih[ets 12. The liquid in the supplied mixture will 65 settle down in the gutters 17 and 18 extending along the conduits 1 6, and is subsequently discharged from the separator chamber 11 via the liquid conduits 19 and 20, respectively. The gas from the supplied mixture leaves the separator 70 chamber 11 via the conduits 16.

In the enlarged part 2 1 of each conduit 1 6 the liquid from adjacent liquid conduits 19 and 20 is mixed with the gasstream passing through said conduit 16, so that a mi:ct'jre of liquid and gas 75 subsequently enters into the heat exchange tube 13 pertaining to said conduh 16. As the conduits 16 are interconnected via the enlarged parts 21 thereof, the gas/liquid mixtures in the conduits 1 6 can be redistributed over the heat exchange tubes 80 13. When the entrance of the heat exchange tube 13 pertaining to a conduit 16 is clogged due to for example contaminations in the gas/liquid mixture, the mixture from said conduit 16 will flow via the interconnected enlarged parts 21 to heat 85 exchange tubes 13 not being clogged.

In the embodiment of the invention shown in Figures 3 and 4 the enlarged parts 21 of the conduits 16 should have such a small cross sectional area that settlement of liquid in the 90 bottom parts of these enlarged parts 21 is prevented.

Reference is now made to Figures 5 and 6 showing a second alternative embodiment according to the invention.

95 The heat exchanger partly shown in these

Figures comprises a series of heat exchange tubes 30, each being secured in an opening of the bottom part 31 of an elongated vessel 32. The interior of said vessel 32 comprises a separator 100 chamber 33, provided with a plurality of inlets 34 for the supply of fluid to said separator chamber 33. The separator chamber 33 is in fluid communication with the heat exchange tubes 30 via a series of a conduit 35.

105 For inspection and maintenance of the heat exchange tubes 30 each conduit 35 is provided with a removable plug 36, arranged opposite to a corresponding heat exchange tube 30.

The bottom of the separator chamber 33 is 110 provided with a lowered part forming a gutter 37 extending along the series of heat exchange tubes 30. Liquid collected in the gutter 37 is supplied to the interior of the conduits 35 via a series of liquid conduit 38. The separator chamber 33 further 115 comprises baffles 39 for dividing the supplied fluid flows over the separator chamber 33, each baffle 39 being arranged in front of an inlet 34. During operation gas from a gas/liquid mixture supplied via the inlets 34 into the separator chamber 33 120 will flow via the conduits 35 into the heat exchange tubes 30. The liquid in the gas/liquid mixture will be collected in the gutter 37 and subsequently discharged from the separator chamber 33 via the liquid conduits 38. In each 125 conduit 35 the liquid from a liquid conduit 38

pertaining to said conduit 35 is remixed with the gas flowing through said conduit 35, prior to entering the corresponding heat exchange tube 30.

130 The invention is not restricted to the types

GB 2 100 851 A 3

gutters for collecting liquid as shown in the drawings, provided than the gutter(s) extend(s) along the conduits 6, 16, 35 forming the main fluid communication between the separator 5 chamber and the heat exchange tubes.

Further the invention is not restricted to the cross sectional shapes of separator chambers shown in the drawings. Any other cross sectional shape, such as a hexagonal shape can be applied 10 without departing from the invention.

Although heat exchangers have been shown comprising parallel heat exchange tubes cooperating with elongated separator chambers, other arrangements of heat exchange tubes are 15 also possible. The heat exchange tubes may for example be arranged according to the radii of a circle, thereby communicating with a circular or annular separator chamber. In this embodiment the gutter(s) for collecting liquid will have an 20 annular shape.

Instead of the slot(s) 9 arranged in the walls of the conduits 6 shown in Figure 2, for the withdrawal of liquid from the gutters 7 and 8, the walls of the conduits 6 can be provided with any 25 other type of openings provided that these openings are arranged at a level above the lower ends of the gutters.

Claims

1. Heat exchanger provided with a series of 30 heat exchange tubes, comprising a separator chamber, a supply for a gas/liquid mixture to the separator chamber, a series of conduits, each conduit forming a fluid communication between the separator chamber and a corresponding heat

35 exchange tube, at least one gutter for collecting liquid extending along the series of conduits, and means for causing liquid from the gutter to flow to each gasstream passing through the corresponding conduit.

40

2. Heat exchanger as claimed in claim 1, comprising two gutters extending along and at opposite sides of the series of conduits.

3. Heat exchanger as claimed in claim 1 or 2, wherein the means for causing from the gutter(s)

45 to flow to each gasstream comprises a series of liquid conduits.

4. Heat exchanger as claimed in claim 1 or 2, wherein the means for causing liquid from the gutter(s) to flow to each gasstream comprises an

50 opening arranged in each of the walls of the series of conduits at a level above the lower end(s) of the gutter(s).

5. Heat exchanger as claimed in claim 4, wherein the lower ends of the openings in the

55 walls of the series of conduits are arranged at the same level.

6. Heat exchanger as claimed in any one of the claims 1—5, wherein each conduit comprises an enlarged part.

60

7. Heat exchanger as claimed in claim 6,

wherein the enlarged parts are interconnected for redistributing fluid over the series of heat exchange tubes.

8. Heat exchanger substantially as described

65 with particular reference to the accompanying drawings.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1983. Published by the Patent Office 25 Southampton Buildings, London, WC2A 1AY, from which copies may be obtained.