GB2039022A

GB2039022A - An assembly of tubular heat- exchanger elements

Info

Publication number: GB2039022A
Application number: GB7943874A
Authority: GB
Original assignee: MAN Maschinenfabrik Augsburg Nuernberg AG
Current assignee: MAN AG
Priority date: 1978-12-20
Filing date: 1979-12-20
Publication date: 1980-07-30
Also published as: AT366818B; IT1126645B; FR2444913B3; SE7910563L; BE880779A; DE2855045A1; IT7928286A0; ATA793079A; ZA796940B; FR2444913A1

Abstract

The assembly comprises a plurality of tubular heat-exchanger elements (3) arranged substantially in a circle, there being no intermediate walls extending parallel to the longitudinal axis of the tubes between adjacent heat-exchanger elements. Each heat-exchanger element (3), viewed in section perpendicular to the longitudinal axis of the tubes (4), has at least one intermediate wall (6). In order to reduce the need for thick reinforcement between the heat- exchanger elements, the elements, viewed in section perpendicular to the longitudinal axis of the tubes, are formed as regular hexagons or polygons having more than six sides, and each heat-exchanger element (3) has a central space (5) containing none of the said tubes (4) and extending over the whole depth of the heat-exchanger element and being provided with supply and discharge pipes (7) for heat-exchange fluid. <IMAGE>

Description

SPECIFICATION An assembly of heat-exchanger elements of the "gas-tube type" The present invention relates to an assembly of heat-exchanger elements of the "gas-tube type".

In such assemblies the heat-exchanger elements are formed as transportable units each provided with feed and discharge means for heat-exchange fluid. There are no intermediary walls extending parallel to the longitudinal axis of the tubes between adjacent transportable units of the heatexchanger elements, and each heat-exchanger element has at least one intermediary wall viewed in section perpendicular to the longitudinal axis of the tubes.

Known heat-exchanger elements of this type have a rectangular shape viewed in section perpendicular to the longitudinal axis of the air tubes. Heat-exchange fluid is fed and discharged through connections in side chambers (water chambers when water is used as heat-exchange fluid) the walls of which form the side walls of the heat-exchanger units, which are rectangular viewed in section perpendicular to the longitudinal axis of the air tubes. The feed and discharge pipes run adjacent to the chambers. This known arrangement of heat-exchanger elements has the disadvantage that the rigid construction, particularly of concrete, between the heatexchanger element units must be relatively thick.

Thus, amongst other things, the cross sectional surface of the arrangement is not used to best advantage, particularly when used in a dry cooling tower.

An object of the invention is to provide a heatexchanger element assembly, which allows the rigid construction to be formed as thin as possible.

The invention provides a heat-exchanger element assembly comprising heat-exchanger elements of the "gas-tube type" arranged substantially in a circle, wherein there are no intermediate walls extending parallel to the longitudinal axis of the tubes between adjacent heat-exchanger elements, and each heatexchanger element, viewed in section perpendicular to the longitudinal axis of the tubes has at least one intermediate wall, and wherein the heat-exchanger elements, viewed in section perpendicular to the longitudinal axis of the tubes, are formed as regular hexagons or polygons having more than six sides, and each heatexchanger element has a central space containing none of the said tubes and extending over the whole depth of the heat-exchanger element and being provided with supply and discharge pipes for heat-exchange fluid in the respective heatexchanger element.

In such an assembly, the thickness of the rigid intermediate constructions can be reduced because of the distribution of the rigid intermediate constructions over a larger side-wall length. Furthermore, the cross-sectional surface of the assembly can be better used because of the arrangement of the pipes for the heat-exchange fluid in planes above and below the heatexchanger elements, and the omission of side chambers. The overall usage of the cross-sectional area can be greater than in the known arrangement previously described.

Preferably, the heat-exchanger elements are arranged together in groups having an outer contour, when viewed in section perpendicular to the longitudinal axis of the tubes, each in the form of a regular hexagon or regular polygon having more than six sides, or alternatively substantially sector shaped.

A high efficiency can be achieved if a liquid heat-exchange fluid is used, and the heatexchange fluid is fed in passages of equal cross section inside each heat-exchanger element.

Embodiments of the invention will now be described with reference to the accompanying drawings, wherein: Fig. 1 is a plan view of heat-exchanger elements accommodated within a circular surface, Fig. 2 is a plan view of one of the heatexchanger elements with the passages for the heat-exchange fluid removed, Fig. 3 is a section taken along the line Ill-Ill of Fig. 2, Fig. 4 shows a detail of the element of Fig. 2 in perspective, and Fig. 5 is a plan view of a modified assembly of heat-exchanger elements arranged in a circular surface.

In Fig. 1 seven identical heat-exchanger element groups A to G are arranged in a horizontal circular surface, and are connectable and disconnectable with each other. Free wedge shaped surfaces at the periphery are filled by covers 1 in a known way. The groups A to G each have an outer boundary in the form of a regular hexagon. The internediate space between adjacent sections is bridged by rigid construcfions in steel or concrete 2. Furthermore, the outermost free side surfaces of the sections are also rigid, so that the sections may be worked with a fluid under pressure or in a vacuum.

Each group A to G has seven heat-exchanger transporter units 3, i.e. heat-exchanger elements dimensioned so as to be easily transportable. The transportable heat-exchanger units 3 each have an external contour in the form of a regular hexagon so that corresponding sides of adjacent heat-exchanger elements lie adjacent one another and between adjacent heat-exchanger elements there are no intermediary walls extending deep into the heat-exchanger element. Surfaces inside each group, which are not formed from hexagonal heat-exchanger elements (viewed in section perpendicularly to the longitudinai axis of the pipes) are preferably formed by heat-exchanger elements 3' having a diamond-shaped outer contour (viewed perpendicularly to the longitudinal axis of Ithe pipes).

Each transportable unit 3, which is formed as a so-called gas-tube heat-exchanger, has parallel, straight, non-ribbed, circular air or gas flow tubes 4. The ends of the tubes :4 are expanded, e.g. to form a hexagon, and are sealingly connected to each other in relation to the heat-exchange medium. Each transportable unit 3 has a central space 5 extending over the full depth of the unit and being free from tubes 4. This space has the shape of a regular hexagon (viewed in section perpendicular to the longitudinal axis of the tubes) and has a planar (flat) contour by forming the boundary tubes as pentagons 4' (Fig. 4) instead of hexagons. The planar outer contour of each transportable unit 3 may be similarly formed.

Members permitting thermal expansion and contraction, preferably in the form of U-shaped elements 8 (Fig. 4), are provided between adjacent transportable units 3 in the region of the pentagonal ends of the tubes 4.

Each heat-exchanger element (viewed in section perpendicular to the longitudinal axis of the tubes 4) has an intermediary wall 6 or several intermediary walls so that, because of the spacing determined by the,U-shaped members 8 and the corresponding formation of the intermediary walls in the region of the outermost side surfaces, a multi-path flow through the heat-exchanger element transverse to the tubes 4 is possible.

Heat-exchange fluid is fed by means of a pipe system 7a above the heat-exchanger elements, and extending to the centres of the separate groups A to G. Pipes 7b extend perpendicularly from the pipe system through the spaces 5 of the units 3. Further pipes 7c branch from the pipes 7b of the transportable unit situated in the middle (shown schematically only for group G). The pipes 7c extend to the centres (free spaces 5) of the remaining units 3 of group G and to the filling elements at the edge of group G. (The piping for groups A to F is the same as that already described in relation to group Gl. The spaces 5 are enclosed at the top and bottom by walls. The fluid pipes 7b supplying the spaces 5 are provided with openings adjacent the spaces.

Heat-exchange fluid is removed by a similar piping system (not shown) extending beneath the heat-exchanger elements arranged at a corresponding height above the floor. Preferably, the outlet piping of the heat-exchange fluid is arranged 1800 with respect to the inlet pipe system for the heat-exchange fluid, so that fluidflow pressures are equal.

If the heat-exchange fluid is a liquid, e.g. water, then- the liquid flows from the space 5 inside the units 3 along passages 9 (Fig, 2) of equal cross section in a direction transverse to the longitudinal axid of the tubes in an outwards and inwards direction.

If the units 3 are each provided with a single intermediate wall 6, then the heat-exchange fluid flows first through the passages 9 in the upper half of each heat-exchanger element from the inside to the outside, flows downwardly through an angle of 90" into the lower half of the heatexchanger element, and then flows as a result of a further 900 turn, through the corresponding passages from outside towards the inside.

The boundaries of the passages 9, viewed in section perpendicular to the longitudinal direction of the tubes 4, have the shape of involutes 10 (Fig.

2), or a substantially-involute shape formed from pianar (flat) wall parts. Preferably, the involutes 10 start at the edges of the inner regular hexagon and end at the edges of the outer regular hexagon.

In the embodiment according to Fig. 5, the transportable units 3, as described above, are arranged into three separable groups A, B, C, and at the circular periphery are accommodated, e.g.

in a dry cooling tower. Each group is substantially sector shaped. The groups have a rigid shell, which consists of metal sheets or walls 11 suitably corrugated to fit against the outer hexagons, the corrugations being fixed to the corresponding hexagon sides of the heatexchanger elements adjacent the tube ends.

The centre 12 of the circular surface does not contain a heat-exchanger element. The centre 12 has the shape of a regular hexagon viewed in section perpendicular to the longitudinal axis of the tubes 4) the contour of which is formed by the respective corrugations of the shells. Preferably, the main pipe-line 13 for the heat-exchange fluid is arranged in the centre and flows upwardly from below. The pipes 14 branch from the main pipeline 13 above the heat-exchanger element at 1200 to each other. Further pipes 15 branch from the pipes 1 4 for supplying individual rows of heatexchanger elements. The pipes 14 and 15 supply the heat-exchanger elements with heat-exchange fluid. Corresponding return pipes for the heatexchange fluid are shown in broken line in Fig. 5.

By the term "gas-tube heat-exchanger" is to be understood a heat-exchanger having tubes through which air or gas flows, whereas the heatexchange fluid flows outside the tubes.

By a "ribless" tube is to be understood a tube that has no ribs enlarging the surface passed which the gas flows. However, the tube may be provided with peripheral beading for producing or maintaining a turbulent gas flow.

The cross section of the tubes 4 in the region where the heat-exchange fluid flows can be, e.g.

four sided.

Claims

1. A heat-exchanger element assembly comprising heat-exchanger elements of the "gastube type" arranged substantially in a circle, wherein there are no intermediate walls extending parallel to the longitudinal axis of the tubes between adjacent heat-exchanger elements, and each heat-exchanger element, viewed in section perpendicular to the longitudinal axis of the tubes, has at least one intermediate wall, and wherein the heat-exchanger elements, viewed in section perpendicular to the longitudinal axis of the tubes, are formed as regular hexagons or polygons having more than six sides, and each heatexchanger element has a central space containing none of the said tubes and extending over the whole depth of the heat-exchanger element and being provided with supply and discharge pipes for heat-exchange fluid in the respective heat exchanger element.

2. A heat-exchanger element assembly as claimed in claim 1, wherein the heat-exchanger elements are arranged together in groups, the outer contour of each group, viewed in section perpendicular to the longitudinal axis of the tubes, being in the form of a regular hexagon or regular polygon having more than six sides.

3. A heat-exchanger element assembly as claimed in claim 1, wherein the heat-exchanger elements are arranged together in groups, the outer contour of each group, viewed in section perpendicular to the longitudinal axis of the tubes, being substantially in the form of a sector of a circle.

4. A heat-exchanger element assembly as claimed in claim 1, 2, or 3, wherein each heatexchanger element is provided with passages of equal cross section for heat-exchange fluid in the form of a liquid.

5. A heat-exchanger element assembly substantially as herein described with reference to any one of the embodiments shown in the accompanying drawings.